How do I set up the RSSI readout on an XM+ receiver channel? I have an old XM+ receiver that does not do RSSI. Some of the newer ones come with RSSI set up on a channel. How can I set up RSSI to be on a certain channel?

For the sake of the random visitor I must first point out that the XM and XM+ receivers do not include telemetry, as in they don't transmit anything back to your remote over the radio link. What the XM/XM+ do offer, however, is an onboard RSSI readout, i.e. supplying RSSI information directly to the flight controller.

These receivers have two ways of communicating that readout.

The first is the RSSI pad, indicated on the schematic in the receiver's manual.

You can solder a wire to this pad, and it will output the RSSI value as a voltage which can then be read by your flight controller via an ADC pin (usually labeled RSSI). This feature is, as far as I know, always on.

The second, which is the one you're asking about, is transmitting the RSSI readout as one of the RC channels, either channel 8 or channel 16.

To enable the latter option (if it's not enabled) or change the channel, you'll have to flash the corresponding firmware to the receiver. If you go to the FrSky site, to the page that offers firmwares for your receiver, and download the archive, you'll see six files, labeled something like:

XM+FCC170313.frk
XM+FCC170313-RSSI16.frk
XM+FCC170313-RSSI8.frk
XM+LBT170313.frk
XM+LBT170313-RSSI16.frk
XM+LBT170313-RSSI8.frk

The files ending in RSSI8/RSSI16 are the ones you need to flash to enable RSSI readout to the corresponding channel; the ones without any suffix have this feature disabled, if you want all the channels as actual channels and use the analog RSSI readout. Also remember to flash the RF option (FCC or LBT) that matches your transmitter, to avoid possible issues when binding.

After flashing, you'll have to rebind the receiver and configure your flight controller to correctly read the RSSI. In betaflight you need the RSSI_ADC option to be enabled to use the first option (analog readout), and you need it to be disabled to use the RSSI-on-a-channel feature. As long as you have the RSSI_ADC option enabled, the RSSI channel setting in the receiver tab won't be saved when you set it.


Why is 5.8ghz used for FPV and 2.4ghz use for transmitters? Why do most VTXs use 5.8ghz and most transmitters use 2.4ghz?

As is discussed in this Oscar Liang article, FPV hardware exists for all different kinds of frequency bands, stretching from 900 MHz to 5.8 GHz, with 5.8 GHz being the most popular today. People in our hobby have tried nearly everything under the sun. :)

Probably the most well-known tradeoff in RF is that between frequency and penetrating power. In general, higher frequency transmissions will not be able to travel as far and penetrate as many obstacles as lower frequencies.

This would make it sound like lower frequencies would always be better, but this is not the case. Especially in the case of FPV video, available bandwidth and interference issues become more of a concern than pure range.

With increased frequency comes higher bandwidth and reduced latency, which is to say that the 5.8 GHz band accessible to us can support more data throughput at a lower latency than the 2.4 GHz band. This is critical because video transmission requires several orders of magnitude more data to be sent than RC controls and telemetry do because it sends entire pictures instead of a few numbers per transmission.

The Troubles With 2.4 GHz FPV Radios

The need for more bandwidth in the 5.8 GHz range is further compounded by the fact that our analog FPV systems usually aren't frequency-hopping. In the old days of the RC hobby when airplanes were the only option, most RC transmitter/receiver systems had a fixed operating frequency. I have a couple of these transmitters, which actually have a slot where you need to insert a special crystal oscillator to select which frequency the transmitter uses!

This became a problem once people started coming together to fly and the RC hobby became more widespread. All of a sudden, people would begin turning on their transmitters at the flying field and their transmitter would talk over other people's transmitters using the same frequency, blasting them out of the sky and interrupting the controls to their plane. (does this sound familiar? XD) This issue was worsened by the fact that the 2.4 GHz band we are allowed to use doesn't allow for very many non-overlapping channels and because the 2.4 GHz band is used by many other different kinds of devices and appliances which can also step on RC transmitters' signals.

The solution to this problem, which has been implemented in the vast majority of all 2.4 GHz RC systems, is to implement frequency-hopping. This feature allows the RC system to dynamically switch between frequencies on the fly as needed, without any input required from the pilot.

These same issues caused by transmitters stomping on each others' signals are also a massive issue in the 5.8 GHz band, but to a far lesser extent due to the vast array of different non-overlapping channels available for use.

 (cit.)


Is WiFi drone control protocol standardized? I'm searching for an app to control a Zerotech Doby drone. The official app "DoFun" is no more available, but surprisingly it works with another Chinese app "FlightGo".
I wonder if the WiFi protocol used there is somehow well known, and if there are any better, preferably opensource apps.

Since no one has answered this question in pretty much a day, I'm gonna spread my half-knowledge now :)
I have never heard of a standardized wifi drone control protocol. However, I wouldn't be surprised if both chinese manufacturers inofficially use the same protocol (be it because they have a contract or because they just copy from each other or because they use the same control chips). I encountered this with a lot of LED strips: Most of these strips can be controlled with the same IR remote - across brands and so on. Even though, IR and WiFi are vastly different things, I think this could be the case here as well.
As for using the same control chips, this is also often the case with toy RC cars (27 and 40MHz). Most of the time, you can just use your remote to control your friend's car. I discovered that in kindergarden ^^.


Why does moving the centre of gravity forward increase stability of a plane? It's a common saying that "A nose heavy plane flies poorly, a tail heavy plane flies once", but why does moving the centre of gravity backwards or forwards change the stability?

TLDR;
Aft CG means stalls are unrecoverable!
Why is CG relevant?
The plane's elevator is the control surface for pitch angle. The elevator is its own proper wing, and as such only has a certain amount of force it can develop before it stalls. Once it stalls, then pitch control is lost. Not a happy day.
The force that the elevator must develop is the lever arm required to balance the torque stemming from the distance between the airframes center of gravity (CG) and the wing's aerodynamic center.

Think about it as a see-saw with an elephant sitting close to the center, being balanced by a mouse 100x farther out.
The upshot is that if the CG is aft of the aerodynamic center, then the plane's nose naturally wants to rotate up, and the elevator has to push the tail up to counterbalance.
And if the CG is fore of the aerodynamic center, then the plane's nose naturally wants to rotate down, and the elevator has to push the tail down to counterbalance.
Aft CG
Aft CG is a huge no-no. It all comes down to stall recovery. If the CG is behind the aerodynamic center, then if the plane stalls the nose will simply not come down. The upshot is that you can never regain airspeed and you will enter into what's called a deep stall or leaf stall.
One common reason for cargo aircraft crashes is improperly secured loads which shift backwards immediately after rotation on takeoff. This moves the CG aft, and the plane can no longer keep its nose down and very quickly stalls unrecoverably. There is a famous video a decade years back of a US military cargo jet which had its cargo load shift back on takeoff while departing a Middle East airbase. All aboard died, and I won't post the link out of sensitivity.
Excessive forward CG
If it's too far forward then your elevator will have to produce a ton of downward force to keep the nose up. This is draggy and inefficient. But it's also (within the limits of reason) survivable.
So where to put the CG?
As far back as you safely can! Competition glider pilots move the CG to the very limits of safety because they want to stop the elevator from producing downward thrust which costs precious meters of altitude.
Jetliners want an aft CG because it saves fuel. But don't panic, they have strict limits on how far back they can move it. Because in equal parts no pilot wants to die and no amount of saved jet fuel ever covers the cost of a crashed plane.


What is this 4th row of pins on some receivers? I was looking for a new receiver(think I fried mine) and noticed that some receivers have a 4th line of pins. I've only seen this on receivers where the connections are on the side instead of the top.
What does this 4th line of pins do? Will it work for my plane just the same as a receiver with only three pins? Is there a reason they only appear when the connections are on the side?
Receiver with 4th line of pins

Modern RC receivers that support PWM/servo output will also support other output modes, which is what the fourth row of pins are usually for.

The extra row of pins you notice on the FlySky FS-iA6B receiver is for extra features of the iBUS signal output. The regular three-high 6-channel PWM outputs are present too.

The FS-iA6B has three different major output modes:

PWM: Each channel (1-6) is output on its own servo channel
PPM: Each channel (I think either 1-8 or 1-10) is output sequentially on one servo channel in accordance with the CPPM (combined PPM) protocol

If enabled, CPPM is output on the PPM/CH1 servo channel

iBUS: Each channel is output over a serial UART connection

If enabled, serial iBUS is output on the PPM/CH1 servo channel
Special auxilary features of the iBUS protocol are available on the 4th row of pins, but these are rarely used. The iBUS signal channel provides all the features usually required fy RC aircraft.

Of the three, iBUS is preferred for use with modern hardware if its supported because of the error-resistant and precision qualities of digital signaling protocols over "analog" ones.


How to prevent a 5V supply from sagging to 4.6V when the FPV camera is on? I have issues with my FPV camera. My camera is a RunCam split 2S (concept is similar to Caddx turtle).

This camera turns off almost instantly after I have plugged in my battery. When I probe the voltage between 5V and ground, I can see the voltage drop from 4.9V to 4.6V as soon as the camera starts recording (which it does automatically when powering it). Then, when the camera shuts completely off, the voltage goes up again. Also, I can press a button and the camera will turn on but also back off again

Hooking up a phone charger to the camera gets the voltage up again (and makes the camera run stably), but I obviously don't want to fly around with a power bank attached to my drone.

Unfortunately, the VTX is also wired to the flight controller's 5V converter instead of its own.

TL;DR: The issue is not that the voltage has too much ripple. The issue is that the voltage converter on my FC is not strong enough.

Would a capacitor at the input (XT60 connector) make any sense? If yes, which size should it be? I have 220µF and 1000µF electrolytic caps.

Links to the mentioned parts: Flight controller, Camera, VTX

EDIT

short answer for future people: additional, external voltage converter/BEC; use all available voltage converters (VTX, FC, (PDB)); do not make them parallel!

long answer: see accepted answer

I've pulled a few specs together from the parts you linked to:

Flight controller:

Input: 2S to 6S LiPo (7V to 20V)
Output: 5V 3A

VTX:

Input: 7V to 24V
Output: 5V 0.3A

Camera:

Input: 5V 0.65A  --OR-- 12V 0.27A

You don't mention what size battery you are using, but I will assume it is in the FCs range of 2S to 6S.

The camera needs too much current (0.65A) to get it's 5V from the VTX (max 0.3A)
The VTX should be connected to the battery
The FC should be connected to the battery
The camera should be connected to the FC 5V supply

This wiring should work, if you have no other large 5V loads connected to the FC.

    ╔══════════════════╗  ╭───────╮
    ║ LiPo Battery     ╟──┤ 7-20V ├────┬──────────┐
    ╚══════════════════╝  ╰───────╯╔═══╧═══╗  ╔═══╧═══╗  ╭────╮
                                   ║  VTX  ║  ║  FC   ╟──┤ 5V ├────┐
                                   ╚═══════╝  ╚═══════╝  ╰────╯╔═══╧═══╗
                                                               ║  Cam  ║
                                                               ╚═══════╝

Alternatively you will need a separate DC-DC converter or regulator to supply the 5V. A capacitor is great for smoothing out surges in demand, but won't hold up the 5V rail if the load is constantly too large.


Cannot configure ESC: BLHeli-Configuator connects but with blank screen ESC: GEPRC STABLE PRO F7 ESC BL32 2-6S 4in1 Specs：35A BLheli_32 ESC

Steps to connect to BLHeli-Configurator:

Connect to flight control (GEPRC STABLE PRO F7 35A) via mini usb
Connect Lipo Battery to drone
Open BLHeli-Configurator from my Windows 10 laptop
Click Connect on the top right corner of BLheli-Configurator. Note, COMM is being read by the configurator
Click Read Setup on the bottom right corner.
On logs, it states:
"2020-06-14 @ 13:30:59 -- Reading setup.
2020-06-14 @ 13:31:00 -- Reading setup finished."
Screen is still blank and can't access the ESC items.

Beta flight is not opened while going through this process.
Experienced this on two drones with the same ESC(built two drones in my life).

Trying to change the spin on my motors, any help would be appreciated

Try using BLHeliSuite32 instead, since it is a BLHeli_32. I don't think BLHeli configurator works with 32 bit ESC:s, correct me if I'm wrong.

If that does not work, try having Betaflight configurator open WITHOUT connecting. This has helped me sometimes.

If it still does not work, you might need to connect to the ESC without using passthrough (if possible) and try to reflash it with a newer BLHeli_32 version.


Can the DJI fpv remote be used with a 2nd radio in a buddybox setup? I’m trying to introduce my children to fpv. It would be great if there was a way to setup a buddybox that used DJI’s remote as either master or slave. I only have the DJI remote currently, so it would be a bummer to need 2 new radios to accomplish this.

If DJI was the slave I realize I’d need to use a different receiver, I have some old R-XSRs I can use.

According to this thread, the answer is that the DJI FPV system doesn’t natively support BuddyBox.

However, they do mention that you may be able to use an R-XSR, and feed the SBUS output of the Air Unit into the SBUS in pad to use it as a backup receiver.


How do I set up IRC Tramp for my HGLRC Forward VTX? I have a Diatione Mamba F405 MK2 and a HGLRC Forward VTX on my 6s race quad and I can't control the vtx using betaflight. The video transmission itself works fine, I just have to use the button on the board.

It says "Device Ready: No" in the betaflight configurator vtx tab and any parameters that I set there are ignored. In the OSD vtx menu the status line reads * UF ---- ----.

Here is my wiring and my ports configuration. It looks fine to me.

And here is my full diff.

# version
# Betaflight / STM32F405 (S405) 4.2.0 Apr 29 2020 / 08:08:49 (b480103d4) MSP API: 1.43
# config: manufacturer_id: DIAT, board_name: FURYF4OSD, version: 3a35e73b, date: 2019-09-30T05:46:12Z

# start the command batch
batch start

board_name FURYF4OSD
manufacturer_id DIAT

# name: Sea Breeze

# beeper
beeper -ON_USB

# beacon
beacon RX_SET

# serial
serial 0 64 115200 57600 0 115200

# aux
aux 0 0 0 900 1300 0 0
aux 1 1 1 1300 1700 0 0
aux 2 13 2 1700 2100 0 0
aux 3 35 1 1800 2100 0 0

# vtxtable
vtxtable bands 6
vtxtable channels 8
vtxtable band 1 BOSCAM_A A CUSTOM  5865 5845 5825 5805 5785 5765 5745 5725
vtxtable band 2 BOSCAM_B B CUSTOM  5733 5752 5771 5790 5809 5828 5847 5866
vtxtable band 3 BOSCAM_E E CUSTOM  5705 5685 5665 5645 5885 5905 5925 5945
vtxtable band 4 FATSHARK F CUSTOM  5740 5760 5780 5800 5820 5840 5860 5880
vtxtable band 5 RACEBAND R CUSTOM  5658 5695 5732 5769 5806 5843 5880 5917
vtxtable band 6 IMD6     I CUSTOM  5362 5399 5436 5473 5510 5547 5584 5621
vtxtable powerlevels 5
vtxtable powervalues 25 50 100 200 400
vtxtable powerlabels 25 50 100 200 400

# master
set dyn_notch_width_percent = 0
set dyn_notch_q = 250
set dyn_notch_min_hz = 70
set dyn_notch_max_hz = 350
set acc_calibration = 62,-10,158,1
set min_check = 1005
set max_check = 1995
set rssi_channel = 16
set rssi_src_frame_errors = OFF
set rc_smoothing_derivative_type = PT1
set fpv_mix_degrees = 25
set dshot_bidir = ON
set ibata_scale = 115
set beeper_dshot_beacon_tone = 3
set small_angle = 180
set pid_process_denom = 2
set osd_vbat_pos = 450
set osd_rssi_pos = 2106
set osd_tim_2_pos = 2519
set osd_flymode_pos = 2082
set osd_throttle_pos = 2466
set osd_current_pos = 2505
set osd_mah_drawn_pos = 2512
set osd_warnings_pos = 14729
set osd_avg_cell_voltage_pos = 2498
set vtx_band = 1
set vtx_channel = 1
set vtx_power = 3
set vtx_freq = 5865
set gyro_1_align_yaw = 1800
set name = Sea Breeze

profile 0

# profile 0
set dyn_lpf_dterm_curve_expo = 6
set vbat_sag_compensation = 100
set anti_gravity_gain = 5000
set iterm_relax = RPY
set p_pitch = 32
set d_pitch = 27
set p_roll = 29
set d_roll = 25
set p_yaw = 31
set d_min_roll = 16
set d_min_pitch = 18

rateprofile 0

# rateprofile 0
set rates_type = QUICK
set roll_rc_rate = 120
set pitch_rc_rate = 120
set yaw_rc_rate = 120
set roll_srate = 90
set pitch_srate = 90
set yaw_srate = 90

# end the command batch
batch end

I have redone all solder joints and checked for continuity with my multimeter.
Is my wiring maybe just wrong? Or is my vtx broken?

(I'm using a betaflight 4.2 rc version, but I've also had this issue with 4.1)

Edit: I contacted the HGLRC support and they told me that IRC Tramp is indeed the correct protocol and they gave me a vtx table which was identical with mine.

Since you confirmed that the protocol+vtx table is correct I'd focus on the physical connection. One explaination would be that the signal is disturbed and the vtx has a hard time decoding it.

Try to disconnect all other components and focus just on the fc+vtx. Try to isolate the SMA connector of the vtx from any carbon parts/metal parts of the frame. Another option is to twist the cables going from the fc to the vtx. You could also add capacitors to the power supply.

If nothing works I'd try a different vtx and check if the problems carry over the new vtx. Adding a phono of your wiring could also help to identify the issue.


How does one wire an OSD-enabled external DVR into Fat Shark goggles? I've recently bought an Eachine Pro DVR which I want to add to my trusty FatShark Attitude v2 goggles.

Wiring the DVR to be able to record video is easy: just solder the DVR's video input wire to the receiver module's output. However this DVR also has a video output, to which it can display its own OSD and menus, or replay recorded footage.

I'd like to take advantage of these features, which means I need to wire that output back into the goggles somehow.

As far as I know, Fatshark's own builtin DVR in their later models also has an in-goggle OSD and video replay, and apparently it's wired right into the module's video feed such that its output gets intermixed with the original signal and the menus look transparent unless you turn off the module. Does that mean it's okay for me to wire the DVR's output directly to the module's output (essentially shorting it with its own input pin)?

Or do I have to somehow splice the DVR into the signal path, so that the goggles will see only the DVR's output at their input? Is such a splice going to degrade the latency of my goggles if I do? If I do the splicing, what's the best way of going about it? I'm good enough at soldering to cut traces and solder tiny wires to them, but I'd rather not do that if I can avoid it.

I have an external fpv monitor with this DVR and if I watch the DVR live feed a delay in the video image is noticable. If the DVR does lock up while flying you are in big trouble. So I'd strongly advise against the "fly via DVR output" solution.

But there is another solution: You can connect the DVR output to the usual AV input of the goggles (next to the power plug). On the bottom side of the googles there is a switch to turn off the receiver module. When the internal module is deactivated the goggles show the video from the AV plug.

This picture shows the pinout of the AV cable (comes with the googles). I don't know if the DVR can be connected to the AV plug permanently or if this would cause interference if the module is active.


How do I wire up this transmitter and camera I'm a total newbie to FPV and electronics. My son bought the following components as an adventure into FPV for his Remote Control vehicles (cars, planes, drones).

Descriptions of the components:
Eachine TX805 5.8G 40CH 25/200/600/800mW FPV Transmitter TX LED Display Support OSD/Pitmode/Smart Audio
https://www.banggood.com/Eachine-TX805-5_8G-40CH-25-or-200-or-600-or-800mW-FPV-Transmitter-TX-LED-Display-Support-OSD-or-Pitmode-or-Smart-Audio-p-1333984.html
RunCam Swift 2 600TVL 1/3 CCD 2.5mm/2.3mm/2.1mm FOV 130/150/165 Degree Mini FPV Camera PAL with MIC Support OSD
https://www.banggood.com/RunCam-Swift-2-600TVL-1-or-3-CCD-2_5mm-or-2_3mm-or-2_1mm-FOV-130-or-150-or-165-Degree-Mini-FPV-Camera-PAL-with-MIC-Support-OSD-p-1118948.html
Eachine ROTG02 UVC OTG 5.8G 150CH Diversity Audio FPV Receiver for Android Tablet Smartphone
https://www.banggood.com/Eachine-ROTG02-UVC-OTG-5_8G-150CH-Diversity-Audio-FPV-Receiver-for-Android-Tablet-Smartphone-p-1242422.html
The transmitter says it takes between 7 and 24V - so the first issue is to find a battery to power this that fits the connector it has. I don't know how to describe the connector it has so I don't know how to find a compatible battery.
Second, from what I understand the transmitter has 5V out to power the camera, but I don't know how I'm supposed to attach the 2 together.
My first objective is to get the transmitter and camera connected, with a battery to power the transmitter - so we can at least get something working. Can anyone help me understand what I need to do?
Thanks in advance...

These components can be split into two functional groups, one for transmitting a picture and one for receiving it, which aren't connected to one another by wires. The Runcam camera and Eachine VTX are both parts of the transmitting section, while the receiver doesn't need to be soldered to anything else in the receiving part.
Required Soldered Connections:
You'll need to make the following wire connections between the different components: (splicing together the components' connector pigtails is recommended as opposed to trying to solder directly to the camera)

Battery+ → VTX 7-24V wire
Battery- → VTX GND wire (there are a total of two available, choose either one)
Battery+ or VTX +5V wire → Runcam 5-36V wire
Battery- or VTX GND wire → Runcam GND wire (in 5-pin camera connector, not the 2-pin camera controller connector)
Runcam Video wire → VTX VIDEO wire

Essentially, both the camera and VTX need to be connected to each other for the analog video signal (one wire) and each need to have connections to ground/GND and a positive voltage source within their requirements.
Battery Setup:
In this setup, the VTX is actually the component that constrains the kind of power sources/batteries you can use. It requires 7-24V to operate, which means you can use 2S-5S LiPo batteries with it. (or another battery pack within the same voltage range)
Most drone/RC LiPo batteries these days come with either an XT30 or XT60 connector, but can be purchased with other terminations. See this page for a list of the most common ones. Once you know what your battery's connector is called, you can purchase a set of connectors online and solder them to the VTX and camera as required.
It's unlikely you'll be able to match the connectors that come with the parts together. While the connectors are all off-the-shelf parts, their usage is unfortunately not really that standardized between manufacturers. You're probably better off just cutting the cable that came with the camera in half and soldering it together with the pigtail wires that come with the VTX.
Once this is done, you can hopefully power on the VTX, camera, and receiver without issues, (remember to screw on the VTX's antenna before powering up so you don't damage it!!!) set the VTX and receiver to the same channel, and view the picture on the connected Android phone/tablet.
Did I leave something out? Please let me know if I did and something doesn't make sense...


Why is it bad to power up a drone without an antenna on the VTX? I've heard a few times now that if you power up your drone you have to make sure that you have an antenna on the VTX. Is that true? If so, what will happen if I power up my drone without an antenna on the VTX?

Short answer: Yes, this is very much true. The VTX sends out radio-frequency (RF) energy through the antenna connector and pigtail, and if nothing (or the wrong thing) is connected at the other end, all the energy gets reflected back and could damage your VTX (or just heat it up).

Long answer:

At high frequencies a thing called "impedance matching" becomes very important.

Basically, when a radio wave travels through a wire, the wire presents a certain impedance (a more "generalized" form of resistance) to the signal. Whenever the travelling wave encounters a change in this impedance as it goes through the cable, connectors and other hardware, i.e. it was 50 ohms before a certain connector and becomes 75 ohms after, part of the wave gets reflected back at that point, and the bigger the mismatch, the bigger the percentage that gets reflected.

Any properly designed antenna will have the same impedance (in the frequency range that it was designed for, i.e. 5.8 GHz for a video antenna) as the coaxial cable before it, and dissipate the received radio-frequency energy by radiating it out in the form of radio waves, thus nothing gets reflected towards the VTX. However, If there is nothing at the end of your pigtail, the mismatch is as big as it can possibly be, since nothing connected means infinite resistance. Thus all of the power that the VTX emits gets reflected back towards it and has nowhere to go other than to heat it up. If the VTX is poorly designed, the reflected power could even burn some of the components in it!

Obviously, this gets more important with the more powerful VTXes. If you've got a 25 mW or even a 200 mW VTX, it's probably not going to damage itself if left without an antenna for a while (although you better not risk it anyway). An 800+ mW VTX could do much more damage; in the best case it will just get very very hot.

If you really need to run without an antenna for some reason (which is rare, but possible if you're testing something that needs the VTX to be powered up, but don't want to actually transmit anything), there is an option to terminate the transmission line with a "dummy load" (which is just an powerful resistor that's impedance-matched to the coax and dissipates all the RF power that it gets) instead of an antenna. Note that shorting the connector is also going to reflect all the power back to the VTX; zero resistance is no better than infinite resistance.

Also, beware of antennae that are designed for other frequency ranges. i.e. a 2.4 GHz antenna from your router or radio control might look like it's compatible and will probably even have the same (SMA or RP-SMA) connector, so it'll fit mechanically just fine, but at 5.8 GHz it will have a drastically different impedance and thus transmit only a small portion of the power it receives, with the rest being – you guessed it! – reflected back and heating up your VTX.


Effect of motor load on ESC? I know that when a prop is caught on something or is slowed down by something it can put extra strain on the ESC or even burn it out.

If I was using a 2207  motor with an unusually large and heavy prop, would I need a more powerful ESC to compensate for the extra load of the large prop?

Would the ESC just need a higher Amp rating in order to operate under the increased load?

The primary thing that high torques affect in a brushless motor is the current flowing through. It obviously affects your ESCs, but also the motors themselves: high currents have been known to melt/burn the insulation on motor windings, which then short out and wreck the motor itself and possibly the ESC as well.

If the source of this torque is just a prop, the best way to see the actual effects of it on your particular motor would be to find a datasheet/spec sheet for it that lists thrust and current consumption for different combinations of supply voltage, prop, and throttle percentage, like this one:

Not all manufacturers provide this kind of data, however. If yours doesn't, or you desire additional information, it's a good idea to browse the site miniquadtestbench.com. They publish the same kind of data, gained from thrust-testing a big range of motor-prop combinations in the lab, and have a handy search tool to find and compare test results for different motors, props and throttle settings. The graphs might be somewhat confusing at first, though:

MQTB tends to use a greater variety of actual props, but the selection of motors is understandably limited.

If you don't find data on your particular motor in either of these sources, and you only need a ballpark, looking at specs of other motors of the same size and KV should be reasonably close, likely to well within ±10%.


Flysky FS-ia10b output more than 2000 microsecond pulse I just modified a servo to spin 360 degrees by taking out its potentiometer and replacing it with a voltage divider of roughly the same value. So when I use an Arduino, I have to send a pulse of about 2250 for the servo to be controlled. Anything a 1000 microseconds lower and it will just spin and won't respond and same for over a 1000. So what I want to do is to send a pulse from my Flysky receiver of more than 2000 microseconds. Is it possible and if so, how?
Receiver: FS-ia10b
Transmitter: Flysky FS-i6X

I don't think that will be possible. The protocol for analogue radio was a 20ms packet, consisting of up to 9 pulses and a gap. So there were 10 things in a 20ms packet. The receiver would split each packet into 2ms blocks and send each block to a servo. Any pulse longer than 2ms would overlap the pulse for the next channel.
Obviously with digital radio, it's entirely possible to exceed this limit but I think it's unlikely that there will be an easy, built-in way to do it. Once you've set the end points as high as they'll go, I think that's all you can do.
You could use an Arduino to scale up the pulses you're getting from the receiver to the size you need for the servo. An Arduino Nano is a similar size and price to a servo, and easily able to handle that sort of task.
However I think you'd be better to look at why your servo needs such a long pulse. Presumably it worked OK before you modified it, so it should be able to work from a standard pulse. It's possible that you've damaged it during the modification, or that the resistance of your voltage divider is too different to the original potentiometer, or that you've connected it incorrectly.


Can I use LiHV batteries as normal batteries? I have a small drone and the only batteries I can find that fit it are LiHV batteries. Can I use LiHV batteries like normal LiPo batteries? Can I just simply charge a LiHV battery to 4.2v and fly with it?

Yes, you can. The primary difference between LiHV and LiPo batteries is the ability to change them to ~4.35 V/cell instead of 4.20 V/cell with a nominal cell voltage of 3.8 V instead of 3.7 V.

Just like how there's nothing stopping you from only charging your LiPos to 4.1 V/cell instead of their rated full charge @ 4.20 V/cell, there's nothing wrong with charging LiHVs to a "full" charge below their rating.


Can something be mounted underneath a quadcopter rotor? I am a bit of a beginner, so I don't fully understand the way the air flows around the rotors in a quadcopter. My question is in the title, and I am basically wondering if something can be mounted adjacent to the motor, and directly beneath a part of the rotor, or if it will cause poor performance on that rotor. I have a very long camera which I can mount to the front of my drone body, but the edges of the camera lie directly underneath two of rotors. Will this cause performance problems/is it a better idea to mount it above them? Thanks!

If you block the airflow into or out of a rotor, you reduce the lift it can generate (approximately) in proportion to the area you block. That means the motors will have to work harder, and your flight time will be reduced.
Work out what percentage of the total rotor area your camera will block. If it's more than about 20% you should probably look for a larger frame.
Obstructions above the rotors are less critical when hovering (as the rotors are sucking in stationary air from all sides) but in forward flight the airflow is more linear - and rotors don't like working in disturbed air so it's worse for high speed flight.


What is a filtered power pad on flight controller? Having looked at many different flight controllers I saw that many of them have filtered power pads. What does it mean when it says filtered power?

Without knowing more specifics about the board(s) you're asking about, it's more than likely that the filtered power pads on your flight controllers are just the normal output from the 5v voltage regulator on the board which has a capacitor between the voltage regulator output and ground.

Because the 5v regulator's output is shared by all kinds of devices connected to the board, all of which consume different amounts of power and at different times, it's entirely likely that the actual voltage on the regulator's output will have some "ripple" where the voltage oscillates around 5v.

 (cit.)

Some components on the drone which deal with analog signals, like the camera and VTX, may introduce visual artifacts into the image or intermittently drop out if they are fed power with too much ripple. The aim of the filtered voltage output is to smooth out the ripple so the voltage oscillations are far less pronounced. In the above graph, the solid black line is the filtered output.


Accessing the video feed of a cheap FPV drone A while ago, I bought a small and cheap WIFI FPV drone to fly in the office and at home (not outside). It's very funny (It's my first drone ever) and now I would like to access the video stream directly and build my own client because the mobile app is sh*t.
That's the app I need to use to get the video from the drone: Butterfly Ufo Drone.  And that's the link to the drone I bought: KF608 mini HD RC Drone Quadcopter.
To be able to use the app, I need to be in the WIFI network of the drone, so I think I could somehow find out the IP and the target port on which the video will be streamed.
Has anyone ever done something like this? Or does someone know directly a solution?
I'm a software developer so the programming stuff is not a problem. I'm struggling with finding the correct endpoint and stream to catch the video.
Edit: I found a repository on GitHub to hijack some drones. Unfortunately not for mine but for many others. So if someone comes around this question with the same problem try the code from that repository: RCL-RC127

I am a little familiar with this - the task is hard and the suggestion to talk to the hacking side is very wise, to wit - here is a primer from my messing around. (also a software developer w/over 20 years experience).
To find out the IP, that is very easy - look to your router and check on leases or devices.  Unless you have static IP assignments or similar, the IP will change overtime but generally stay the same on a calm network.
For capturing the stream - Wireshark is in your future (https://www.wireshark.org/) and you will need to know the protocol being used and  various transport mechanisms then reconstruct that data for your end use.  It is safe to assume that the guys in Shenzhen took the fast, easy, hacky, free/open source route.  Chips in used will also provide clues.
I have worked a bit in wifi security hiring people to corrupt wifi data for tech presentations - your task is not one I would ever take on (out of my wheelhouse).  Still I have tried this exact hack a few times and have been defeated universally.
I got around this by using a USB HDMI capture box and porting in the analog signal.  $200 part and 1h set up and I can stream from goggle to internet. The capture box is something I am glad I have and the 10days of work I skipped hacking signals is not forgotten.


How do ducted fans impact drone performance? There are many drones available which use ducted fans as opposed to open propellers. How does a ducted fan quadcopter differ in performance from an open-prop quadcopter?

Note: the other question asking about shrouded propellers is different and its answers do not answer this question because it asks specifically about the impact the shroud has on the production of yaw by the torque produced by the propellers.

There are a number of performance differences between open-blade quadcopters and ducted fan quadcopters and they may depend on the shape of the ducts.

In theory, the most notable difference in performance is the increase in either hovering efficiency or increase in thrust. When a drone has the ideal shape of ducted fan, it could decrease battery consumption by up to 60% or almost double the thrust. However, many drones that use ducted fans don't have a duct with optimal shape or have heavy ducts and thus won't get as significant advantages.

An optimal duct for hovering would look something like this:

Also, for larger quadcopters, creating a ducted fan with tight tolerances would probably add a lot of weight which would diminish the usefulness of the duct and if a duct is severely limiting the prop size, it can limit the quadcopter's efficiency because larger props tend to be more efficient.

Another impact on performance that can be caused from using ducts, (especially for high performance or fast quadcopters), is ducts can cause the drone to react strangely when performing aerobatic maneuvers because the ducts can catch the wind and push the quadcopter off course. The ducts can also add more drag when the quadcopter moves fast. An open-blade quadcopter is generally smoother when performing fast movements or maneuvers.

In the end, If a drone has ducts with tight tolerances that don't add too much weight and has the "optimal" duct shape, it will probably be more efficient and get better flight time than a similar open-blade quadcopter but it may be less smooth and efficient when performing fast aerobatic maneuvers.

Source of information about efficiency: The ideal shape for a multirotor ducted-fan


ESC shutting down when motor loaded I have a BLDC motor and a 300 amp ESC, The ESC shuts down after a few seconds at full load. The motor only draws 2 amps at full throttle, full load and the voltage only drops .5 volts. The battery is 6-s 8-p and has been tested, all cells are good My question is what is triggering the shutdown in the ESC?  I have it set at 3v per cell which would be 18v It never get's lower than 24v. Nothing gets hot, it isn't on long enough to even get warm. If it's not the LVC is there something in the ESC that tells it is drawing to much current? Could it be the back EMF is not triggering the sequence correctly?  I'm using an Arduino connected to the ESC instead of RC, Could there be anything in the code I could adjust?
#include <Servo.h> //Using servo library to control ESC
Servo esc; //Creating a servo class with name as esc
void setup()
{
esc.attach(10); //Specify the esc signal pin,Here as D10
esc.writeMicroseconds(1000); //initialize the signal to 1000
Serial.begin(9600);
}
void loop()
{
int val; //Creating a variable val
val= analogRead(A0); //Read input from analog pin a0 and store in val
val= map(val, 0, 1023,1000,2000); //mapping val to minimum and maximum(Change if needed)
esc.writeMicroseconds(val); //using val as the signal to esc

Motor: SSS 56114 360KV Brushless 1/5 Motor 13.000W 56114mm for Boat, car and Surfboard Maximum Amps: 95A Max volt: 125V.

ESC:  SPECS 300A BOAT ESC Flier mod. R-Snake Voltage (LiPo): 3-12S Voltage: 12V to 50V Anti-spark cable: yes Wires: 8AWG Connectors: 8mm Bullet BEC: No Size (mm): 2405735 Weight: 387g

This is a custom build so there is no other info on the prop.

This has already happened to me, the problem was ESC configuration.
I was using a LiFe battery (3.3V/Cell) and the Low Voltage Cut-Off Threshold ESC configuration was about to cut the current with 3.2V/Cell. Look for the programmable settings of your ESC and check how it is.


Can boosting the Caddx vista to 1200mw cause damage to the unit? What can happen to your Caddx Vista camera if you boost its output to 1200mW? Could it be damaged in any way; including overheating?

As far as I can tell, after doing some digging, There are a few things to consider when boosting a Caddx Vista to 1200mw. First, the Caddx Vista tends to get hotter that the DJI air unit, so heat is one thing to consider. If the drone is flying, there should be enough airflow to dissipate the heat, so 1200mw shouldn't cause any overheating issues. Just make sure the drone isn't sitting somewhere with the Vista on a high-power setting.

Another thing that seems to happen when using a higher power setting (whether that be 1200mw or just 1000mw) is that the bit rate drops. Several people claim that when flying with 1000/1200mw, the bit rate drops and causes lower image quality.

See here starting with post #84 on page 6 and then the beginning of page 7.


Motor will not go above half thrust. Why and how to fix? I fixed the esc of my aircraft, but now it won't go above half thrust for whatever reason. Here is a short record of the electronics in the craft;
Crashed twice, broke esc, soldered 3-pin ground connector back to the esc, wrapped in electrical tape, worked fine, all seemed good, now won't go above 1/2 thrust.
When I go above half thrust, the motor will stop spinning, and the plane will beep a few times. After about 3-5 seconds, if I pull the throttle back down to 0 and then push back up, it will resume spinning but still will not go above 1/2 thrust.
I do have a new esc on the way from amazon so that might fix it but still have no idea why the plane won't go above half thrust. Any idea why and how to fix it?
Plane has 1 motor, rudder, and elevator in use. Ailerons were not connected for the flight when I noticed it would not go above half thrust.

This sounds very much like like a PWM/analog ESC miscalibration issue to me. PWM ESCs required signal calibration to ensure that both the RC receiver and the ESC are on the same page about what kind of pulse length constitutes both 0% and 100%, as there can be clock speed discrepancies and other issues with the protocol.

I can't exactly find a source I like for this procedure to explain it better, so here's my rendition: (modified from those listed here)

With ESC power unplugged, connect the ESC signal to the receiver's throttle channel.
Turn on the transmitter and receiver and move the throttle to 100%.
Enable power to the ESC and wait for it to beep a few times indicating it's in calibration mode.
Briskly lower the throttle channel to 0% and wait for the ESC to beep to indicate it's now calibrated
Try to operate the ESC like normal and see if the full-throttle range has been restored


Empty Cells on LiPo - Balance Charger or Battery Problem? I recently opened up a box of 5 year old 3S LiPos which I had in storage. When I hooked them up to my Turnigy Accucel 6 80w balance charger, they mostly measured total voltages around 11v~. However, upon connecting the balance leads, the charger is saying that all of the old batteries have only 2 out of 3 cells carrying voltage (and one was at only 1 of 3). Similarly, when I try to balance charge these batteries, I get a "cell error". It's possible the batteries are bad, but it seems weird for them all to be bad in exactly the same way.

For example, on one of the 3S batteries, voltage reported is:

0.00 6.07 3.87
0.00 0.00 0.00

This shouldn't even be possible, there's no way I have 6.07V in one cell.

I proceeded to test the voltage of these batteries directly with a multimeter (followed this guide) and I'm seeing voltages on all three cells. What's a little odd is on the one I tested, they all seem to report the exact same voltage (3.72V). Testing the main power lead directly, I get 11.16V (3.72V x 3).

It seems reasonable to assume there's something wrong with the balance charger, but I wanted a second opinion. I was able to use the balance charger to successfully charge some new 4S batteries, but I don't have any new 3S batteries handy. Is it possible I just have a problem with the circuitry for the 3S balance connection?

It sounds like the balance lead for the first cell isn't connected somewhere. The wire may have come off inside the charger, or it could be the balance plug, the wire, or an external parallel board (if you're using one).

I'd open up the charger and test the voltage at the back of the balance plug, and see if you can spot any broken solder joints.


How to identify and address multirotor motor overheating When flying my drone, I often notice my drone motors getting hot after a flight and am concerned that it could explode/blow up.

What does a hot drone motor mean?
Is this something to be concerned about?
What could be done to prevent overheating?

Assuming that you've spec'ed a good propeller-motor match and the heat isn't generated by a tiny motor being forced to drive a giant propeller, the heat generation is likely due to a physical issue with the drone, mistaken filter settings, or a tight PID tune.

First of all, it's a good idea to determine whether your motors are actually hot enough to matter. A good rule of thumb I've heard commonly thrown around is that if your motors are SO hot to the touch that you want to take your fingers off after a few seconds, then that's too hot. If you feel like you could keep them there forever, then it's probably not something that will ever be a problem.

Physical Causes

It's possible that you have a mechanical connection issue somewhere on your drone which is causing problems, like if one of the motor fastener screws is protruding into the motor casing and making contact with the windings like in this video from Joshua Bardwell which also goes through troubleshooting steps and how to rectify the issue.

Other physical causes can include locations on the drone where parts or wires (like motor phase wires) that are touching conductive things they shouldn't be. Giving your drone a look over to make sure any of these aren't the problem is worth a try.

Also, make sure that the hot motor is still balanced. If the motor has been damaged, that is almost certainly the cause of the elevated temperature of the motor.

Filtering Issues

If you ever went into the configurator for your flight controller firmware (e.g. Betaflight, Cleanflight, Raceflight, iNav, etc.) and disabled or restricted the default gyroscope filtering settings, it's possible that these are the culprits. Insufficient filtering on the noisy gyroscope signals can result in hot motors because the flight controller tries to respond to the noise it sees in the gyroscope data and not just the pilot's inputs. The inconsistent nature of the gyro noise means that motor commands would be constantly changing up and down, which can be a cause of hot motors.

If you ever tweaked the filtering settings to try and improve their latency, it's possible that any crashes you've since experienced have beat up the drone sufficiently that there is now extra noise that wasn't there before when you adjusted the filters, causing hot motors. In that case, I'd recommend raising the filter sensitivity. The Betaflight Configurator for >4.0 versions of Betaflight makes this super easy with a slider that you could push towards increased filtering.

PID Tuning Factors

As noted in this (admittedly old, for Betaflight <2.x) Betaflight Tuning Guide, motors will start getting hot if your D-gains are too high. I would recommend checking all of the previous situations before pursuing this case because issues with the PID gains are often more subtle and difficult to track down, but a solution here would be to slowly back off on the D-gains in your PID controller until the motors cool down sufficiently.

The D term in the PID controller tries to look ahead into the future and consider if the controller is trying to reach the pilot's input commands quickly enough, attempting to slow the reaction time or speed it up as necessary to minimize overshoot. This system can be completely screwed up if excess noise enters, so checking the filtering settings to make sure nothing is wrong there first is a good idea.


Does the RC transmitter control power consumption? This might be a little off topic, please be understanding.
In case of an RC car toy (specifically, for children) you can control the speed of the car via the transmitter. I am wondering, if I were to customize the transmitter and limit the maximum speed of the car, let's say, to half of the original, do I (or the kids) get to enjoy playing for double the time with the same batteries?
(for the sake of simplicity, let's say that the throttle on the customized transmitter can only be pushed half way)
So does the transmitter control the power consumption of the RC car, or it's only a torque to rpm conversion?
Cheers,
John

Yes, sort-of.
The speed controller switches the motor on and off in very rapid pulses, and the width of these pulses (and the width of the 'off' period) is controlled by the throttle. It's so fast that the motor just sees it as a varying voltage.
So if you cut a piece of card and stuck it on the transmitter to prevent full throttle being used, the speed controller would only run the motor at partial power. The car would accelerate more slowly, have a lower top speed and the battery should last longer. It should break less when you crash too.
However, voltage supplied to the motor is only part of the story. The current drawn from the battery is what's actually important, as battery capacity is measured in Amp-Hours (i.e. a 1AH battery can supply 1 amp for an hour, or 2 amps for half an hour, etc). The current decreases as the motor speed increases. A motor running at full throttle with no load will spin quickly but draw little current but the same motor struggling through grass will be running more slowly and drawing more power.
So if you want longer run time, drive on a smoother, lower-grip surface or change gear ratio to a lower gear so the motor can reach its top speed with less power. Or buy some extra batteries...


Determing the frame's hole mount length, for the right mount size motors How do you find out the frame's motor mount mm length?

And what motors are generally for 3 inch frames and 5 inch frames?

Example:
3inch frames are generally for 1206 or 11XX motors?

5inch frame are generally for 2306 or 22xx motors? Does 23xx or 22xx motor number stand for an identifier?

This blog post by Oscar Liang has a table identifying the type of motor that is used for each frame on 4S (other voltages would only affect the KV). Here is a screenshot of it:

And yes, 22XX means any motor with a stator diameter of 22mm and with any height, as it is the stator diameter that will determine the mounting pattern.


Why is an MPU6000 more well suited for drones than an ICM IMU? I have seen people say that the MPU6000 is the superior gyro chip, even though the ICM chip has a faster refresh rate and is technically superior in any other use.

Why is it better to have a lower refresh rate on a drone’s gyro?

It's not superior, it's just good enough, cheap enough and may be more noise resistant than ICM20602.

There's a bunch of flight controllers with dual IMUs onboard. For example, Lumenier Lux F7 has MPU6000 and ICM20602, you can choose which one to use. SP Racing F7 and H7 series use two ICM20602s fused together.

Also, there's BrainFPV Radix which uses BMI160 from Bosch Sensortec. It should, in theory, provide a more clean and noise resistant signal without the need for complicated software filtering.

Refresh rate is another thing in itself. Things start to get worse with higher refresh rates: you get all sorts of noises internal and external to the IMU, which can negatively affect motor speed regulation, which in turn might make motors run hot or even fry. Also, higher refresh rates require more processing power to filter the noise. Running IMU at 8+ kHz with RPM filtering gobbles up CPU pretty quick to the point that the quad even refuses to arm.


What is a good alternative to carbon fibre for a quadcopter frame? I am making a diy quadcopter and I need a strong and light material for its frame.

Carbon fibre is not available in my area. I have tried aluminium but it's too soft and so needs repairs. What alternatives are recommended?

There's no denying the fact that when it comes to materials that are both strong and light, carbon fiber is king. If you're looking for performance, there's no way around it. If performance is not the most important thing in the world, however... Well, there are several options.

Before I start listing these, I must point out that all frames break. Some break more easily than others, but you can't have an unbreakable frame. The question is how you repair it when it breaks, and the answer depends on the material.

Plastic frames are actually a very popular in micro-sized quadcopters that only weigh tens of grams. These frames usually feature a non-flat shape, prop guards and other features built into them. A subset of those, 3D printed frames, are also quite widely used in DIY designs of larger sizes, and, as everything 3D printed, are a good way of prototyping your design before moving on to other materials. In some cases, where performance is not a concern (for example, if your main focus is having a platform for testing algorithms for which flight time or range is not important at the time, or just want to play around with a design) you may even never move on from a 3D printed frame. While these tend to be heavy and/or brittle compared to other materials, there are some exceptionally light designs, and depending on the intended applications, durability might not be a concern. Besides, if you do break one of these, you can always just print a new one.
Wood and metal/fiberglass is a staple of "oldschool", large (8"+) DIY drones from the KK2/Naze era. As the drone gets larger, heavier frames tend to impede it less, and any crash could easily break an arm just due to the sheer weight of the drone, no matter what the arm is made of. So this kind of design focuses on repairability instead: one can easily make tens of wooden arms in their workshop for very cheap and swap them when they break. Potentially, one could try to make a smaller wooden frame as well, although at this point lightness becomes important, so I'd advise to stick to lighter woods if you do, maybe even balsa.

Full-metal frames are not unheard of as well; Aluminium and titanium are widely-accepted building materials in aviation and actually tend to have better performance than wood. You'll have to use tubes/other non-flat shapes, though.
Even though you've ruled out carbon fiber, you may be referring specifically to CNC machining of frames out of flat sheets. Premade carbon fiber elements such as strips and tubing are readily available for order online and are easy to work with using basic tools. A lot of larger drones today are made using the same basic technologies as the wood/metal drones of old, but with arms out of carbon fiber tubes instead of wooden planks. If you're building a large drone, this is a very feasible yet high-performance option.

Finally, Pure fiberglass composite. Glass fiber composites are significantly less stiff than their carbon fiber counterparts, and heavier as well, but there are a few niche uses even in performance designs.

The first of them is very large drones, which tend not to care as much about neither weight nor aerobatic performance. Here, glass fiber can shine if you've got the facilities to manufacture it. That said, if you're building a very large drone, the frame is likely to be a very small fraction of its cost, so you might just as well order a custom carbon design (or use premade carbon parts like the previous option).
The more interesting option, however, is a PCB frame, in which the frame is
not just a structural component, but also carries all the electronics
that the drone needs to fly. Some fantastically lightweight designs
have been made using this technique: even though the glass fiber
itself is heavier than carbon, the design makes up for it by ditching
all the other PCB and wiring weight that would otherwise be carried
on top of the frame in a traditional design. While not optimal for sporty flying, this is the perfect option for a long-range/long
flight time autonomous design... if you can lay out the PCB, as all
of the components (flight controller, ESCs, vTX, etc) have to be
integrated into it.

Some examples for inspiration:

Plastic frames

Brushed micro quadcopter (tiny whoop) with molded plastic frame:

2" brushless copter with molded frame:

Brushless quadcopters with 3D printed frame:

Foldable brushed 3D printed frame:

Wood/metal homemade frames:

Typical fully wooden H frames of the KK2/Naze era:

Classic X frame with metal/plastic center plate and wooden arms:

Very simple wooden X frame:

Small drone with laser cut wooden frame:

Frame with metal arms:

Full-metal frame:

H frame out of carbon tubing with 3D printed brackets holding it together:

Glass fiber frames

Molded fiberglass tricopter:

PCB frames:


At what current should I charge a LiPo battery? I have several different LiPo batteries which I use with my drones, many of them are different voltages and different capacities. How do I know at what current I should charge my drone LiPo batteries?

Charging Lithium batteries is a far more delicate process than discharging them because of the complex chemical processes involved. Batteries that are rated for tens of "c"s of discharge rate are usually only rated for 1-2 "c"s of charging rate. Standard charging rates are 1c for regular speed and 2c for fast charging, with 2c damaging the battery more.

C-ratings are an artificial marketing term that doesn't really help very much without being converted using this formula: Charging Current (amps) = C-rating * Battery Capacity (amp-hours) where one amp-hour (Ah) is equal to 1000 milli-amp-hours (mAh).

So, for example:

1500 mAh battery charging @ 1c = 1.5 A charging current
2000 mAh battery charging @ 1c = 2.0 A charging current
2000 mAh battery charging @ 2c = 4.0 A charging current
2000 mAh battery charging @ 0.5c = 1.0 A charging current

Charging at higher currents (higher c-ratings) is more damaging to the battery's cells and is more likely to cause complications like fires and explosions while charging. The opposite is true for charging at lower currents. It is hardly ever recommended to charge at more than 2c, and staying as close as possible to 1c is always recommended for safety and battery longevity.


IR and/or Thermal FPV I'm interested in thermal imaging and night vision and applying it to FPV flight. Can anyone recommend a good night vision FPV camera? I've seen the RunCam Night Eagle, and it looks great, if a little expensive. Also, can someone shed light on whether or not it's an IR camera? I'd like to be able to use an IR spotlight or some similar device to light up shadows, but I don't want to have an obnoxious flashlight shining around.

The night eagle (and other 'night' FPV cameras) use visible light, but can work with very low light levels. Moonlight looks like daylight and starlight is flyable. There are plenty of videos that demonstrate what you would see.
Even many ordinary FPV cameras will often work better than normal vision. It's quite common to finish an evening flight and be surprised at how dark it is.
As far as I know, the Night Eagle is still the best but new cameras are released every few months so it's worth checking the latest reviews.
'Night' cameras might pick up some of the nearest IR frequencies, but they're not real IR cameras. You won't see any contrast between hot/cold objects. Real FLIR cameras tend to be expensive, and the more affordable ones are low-resolution and designed for smart phones rather than FPV video transmitters.
I don't think that putting a light on a drone is going to help much until you reach car headlamp brightness, and even then you might find it's too narrow.
I found this commercial FLIR drone but at under 9 frames per second it's not really FPV, and it still looks expensive.


DJI Go Android App Flight Simulator So I have two DJI platforms, and have had them for about 6 months now. I keep seeing these references all over the Internet and YouTube about how handy it is to have the DJI simulator built into the app. And how great it is that you can just turn on the remote, configure it with your phone or tablet, just as if you were actually going to fly. But when I do all that and get to the first DJI Go app page, you know, where it shows which aircraft you can select, there is no simulator app.

So I'm running a DJI Phantom 3 Standard and a DJI Inspire 1 v2.0, both using the same DJI Go app. I'm all Android all, the time so hopefully it's not another one of these "iOS people get it but Android people don't" things.

I do have the DJI Windows 10 PC Simulator App downloaded onto the laptop. And much to my utter shock, after I connected the Inspire controller to the computer with a USB cable, a few false starts, the thing actually loaded and let me fly. But MANNNN is it dog slow. And let's be honest here, I'm pretty sure that downloading a DJI executable was probably not the best decision of my life. But you know what, have at it China, you guys already have literally every single byte of my personal data from when you stole all the Top Secret Clearance applications from OPM. Good thing it wasn't important or anything...

Anyway, didn't mean to digress. So, can anyone help me find, use, and enjoy the Android DJI Go App's Flight Simulator?

I have found where the simulator went, no where. The problem I was having was related to a common theme I'm seeing with many drone apps.
The simulator seems to be available only with iOS versions of the DJI Go app. We converted over from Android for to an unrelated app offering more features with the iOS version than the app's Android version.
So if you're using an Android device and want to have the DJI app, you need to make the transition to an Apple iOS device.


Flying a drone in France In the future, I plan to fly a small (<250 gram) in France, are there any special licenses/permits that have to be obtained? What are the laws on this? Where are the no-fly zones located?

You mention that this will be in the future. While the other answer covers the current situation well, you should note that the rules are due to be harmonised across Europe and this might introduce some changes.

https://dronerules.eu/en/recreational/eu_regulations_updates

The following image summarises the requirements for the new regulations:

This table refers to the new classes, which are intended to make it easier for a consumer to tell what they can do with their drone (new drones should show their class on their packaging) [source]:

Class C0 - (can be flown in all subcategories) Very small unmanned aircraft, including toys, that:

are less than 250g maximum take-off mass
have a maximum speed of 19m/s (approx. 42.5 mph)
are unable to be flown more than 120m (400ft) from the controlling device

Class C1 – (can be flown in all subcategories) Unmanned aircraft that:

are either:

less than 900g maximum take-off mass, or;
are made and perform in a way that if they collide with a human head, the energy transmitted will be less than 80 Joules

have a maximum speed of 19m/s (approx. 42.5 mph)
designed and constructed so as to minimise injury to people

The standards also cover other aspects such as noise limits, height limits and requirements for remote identification and geoawareness systems.

Class C2 – (can be flown in subcategory A2 [close to people] or A3 [far from people]) Unmanned aircraft that:

are less than 4kg maximum take-off mass
designed and constructed so as to minimise injury to people
are equipped with a low-speed mode’ which limits the maximum speed to 3m/s(approx. 6.7 mph) when selected by the remote pilot

The standards also cover other aspects such as noise limits (but different from C1), height limits and requirements for remote identification and geoawareness systems, plus additional requirements if it is to be used during tethered flight.

Class C3 – (flown in subcategory A3 [far from people] only) Unmanned aircraft that possess automatic control modes (such as found in typical multicopter ‘drones’) which:

are less than 25kg maximum take-off mass

The standards also cover other aspects covering height limits and requirements for remote identification and geoawareness systems.  There are also additional requirements if it is to be used during tethered flight, but there is no specified noise limit (because the aircraft is intended to be flown ‘far from people’).

Class C4 – (flown in subcategory A3 [far from people] only) Unmanned aircraft that do not possess any automation, other than for basic flight stabilisation (and so are more representative of a ‘traditional’ model aircraft) which:

Are less than 25kg maximum take-off mass


How are Hall effect gimbals different than standard gimbals? I know that hall effect gimbals are supposed to be better than standard gimbals and are seen on a lot of expensive transmitters. What are the differences between a Hall effect gimbal and a standard gimbal?

The difference is in how the gimbal position is sensed and reported to the processor in the transmitter. The two main types are potentiometer and hall effect gimbals, but in both types, the fundamental mechanism holding the gimbal and allowing it to rotate is the same.

Potentiometer (aka. pots)

Potentiometers are resistors which change their value depending on the location of the wiper along the resistive strip inside them. In a RC transmitter, the wiper is connected to each axis of the stick. The processor in the transmitter reads an analog voltage from the potentiometer and translates that to the axis' value.

 (cit.)

Hall Effect

A hall effect sensor also reports an analog voltage, but this time based on the strength of the magnetic field it senses. A magnet is attached to each axis of the gimbal and a hall effect sensor is placed on each side of the frame of the gimbal. The movement of the magnets either closer or further from the hall effect sensor registers as a changing value for the axis.

Comparison

Potentiometers are generally less precise than hall effect sensors and tend to drift over time, leading to a need to calibrate the center point of each axis every once in a while. This doesn't need to be done with hall effect gimbals.


If AUW is 90 grams, will 4500Kv motors be better than 7500Kv? I have a build that is 90 grams and runs great with 7600Kv motors. My question is, if everything stays the same and I put on 1204 4500Kv motors on it, would I get more flight time? More power or torque? Or both? Thanks

Lower kV motors will spin more slowly but with more torque. Spinning more slowly (with the same prop) will give you less thrust and less power (and thus lower current) at full throttle.
However, a well setup quad doesn't spend much time at full power, especially when you're considering your total flight time. The amount of thrust required to fly is still the same because the weight and drag haven't changed, so if the props are the same they will still need to spin at the same speed. To reach that speed, you'll need more throttle. Top speed will be reduced and if that leaves you flying more slowly than before, your flight times will increase - but you could probably get the same effect just by flying more slowly.
There may be some difference due to the relative efficiencies of the two motors, but it will be small. I don't know which would be better and you probably won't notice it.
However, that assumes you keep the same props. A lower kV motor really needs larger props, so it can generate the same thrust at lower RPM. Larger props should be more efficient because they act on more air and don't have to move it as fast. That should give you longer flight times and more thrust at low speed, with a possible reduction in top speed.
Of course, all that is irrelevant if your frame doesn't have space for larger props.


DIY wireless mesh network to extend drone's operational range I have stumbled upon this question regarding technology providing longest range for rc controls and would like to ask a related one. Theoretically it should be possible to build a wireless mesh network that can route the signal from the drone to the operator and back thus extending the operational range of the drone while relying on the same frequency(/power per unit).

is there an open-source project that implements such a mesh network in conjunction with an open-source flight control?
is it theoretically possible to build the nodes of such a mesh network using Arduino and power them with not too big solar panels?
would it be possible to transmit real time video through such a solar-powered mesh network?
how would such a network, of let's say 5 nodes, extend the operational range of currently available drones?

You can do this with a configuration known as a 'repeater'; there are a number of examples of people using this to convert their favourite controller's RC system to that of a specific aircraft, but you could do the same with a single mode:

FrSky to Dragonlink Repeater
2.4ghz to EZUHF repeater

I'm not aware of an open-source implementation or Arduino examples but the above links show you may be able to use off-the-shelf parts; this is likely to depend on how open your radio hardware is.

Range-wise, the aircraft and controller need to be in range of the repeater but not of each other - so you could theoretically add half as much again but in practice you want a healthy overlap. You could add more than one node but the aircraft still has to stay in range of the last one, as the drone (and each node) can only pair with one other transciever. In theory this same setup should be possible for video too - chain a receiver into a transmitter. It is worth remembering that some VTXs can get very hot if you don't have airflow from the drone, so you may need to add a fan.

With regards power-consumption, the transmitter will be limited (legally, at least) to tens of milliwatts and the microcontrollers won't take too much - it should be possible to power such a system from a smallish solar panel, but you will need to compare the panel output to a measured system draw; then add a margin for safety and a small battery to smooth out demand.


2D/3D/fpv video glasses to use with external camera I do not have any prior experience with FPV goggles (never owned one), but now I am involved in a project where I need to connect a video or FPV glasses to an external camera through a wired connection and watch the camera view on the goggles.
It is important that it is connected to an external camera because I need to achieve that point of view. A person must be able to see his own hands through the camera if he points the camera towards the hands! This is a must.
I have been looking through the internet trying to find some potential glasses that I can test on, and I have found the following:
(Option 1), (Option 2), (Option 3), (Option 4)
Since the goggles and the video camera will always be within a close range, I am at the moment considering a wired connection. I assumed that wired should provide with better quality video compared to wireless. Is that correct? If not, there is absolutely no reason for me to go wired, and I'll go wireless.
For now, I consider wired connection, therefore the goggles must have AV or HDMI input that I could plug my camera into, which is my main concern.
Few questions I have regarding this project

Wired vs Wireless communication between the goggles and the camera? Is it true that using wireless will reduce the preview video quality?

AV or HDMI? I was planning to use an FPV camera such as this, and connect it to my goggles through an AV cable. However, I am concerned about the video quality. Will the HDMI provide better quality video? In that case, I must consider glasses that have hdmi input and must find a small camera that I would be able to conveniently mount on a stick (planning to use something like a selfie stick).

The price is not the biggest problem here. I am willing to spend extra to achieve very good quality video preview through the goggles.
I am hoping to receive some help from people who know about FPV (2D 3D video) goggles, FPV cameras and AV/HDMI. Appreciate any help

Ordinary FPV cameras output an analogue PAL or NTSC TV signal, which you should be able to plug straight into a TV or goggles that are intended for watching TV.
Some FPV goggles only have a receiver and no input socket, but the good ones generally allow you to change the receiver, and thus have a socket for the AV signal. (Also some of the very cheap ones are just a box for a screen from an automotive reversing camera system, and expect you to provide your own receiver)
So, skipping the radio link should be easy enough, which is good because you do get some radio 'noise', especially if you're indoors where the signal can reflect from metal objects, or where there's interference from WiFi and other electronics.
Good quality FPV cameras are generally optimised for a wide dynamic range (so you can still see details on the ground when the sun is in the picture) and low light (it's common to finish an evening flight and be surprised by how dark it really is) and low latency (for racing) but the resolution is usually fairly limited because the radio bandwidth is limited.
It gets harder if you want better resolution. The only real option from the FPV world is the DJI digital FPV system, but it's quite expensive and I don't think you can use it without the radio, which is integrated into the goggles. The goggles may have an HDMI socket, but the camera doesn't.
Then again, there must be HDMI cameras outside of the FPV world. A quick google shows lots of people using DSLRs, and lots of action-cams (like GoPros) have HDMI ports - although I'm not sure if they support real-time video, or just replay. Also, any form of digital processing introduces some lag, and it doesn't take much to make hand-eye coordination difficult.


Can you cancel an automatic landing triggered by a low battery on the Dji Mavic 2 Pro? Whenever the DJI Mavic 2 Pro has a low battery it initiates a function that lands it. Sometimes this can happen when the drone still has a lot of battery capacity e.g. 45%.

Is there a way to cancel this return to home function?

If you have more then enough battery, you can disable it as stated in the manual:

Low Battery RTH
Low Battery RTH is triggered when the Intelligent Flight Battery is depleted to the point that the safe return of the aircraft may be affected. Return home or land the aircraft immediately when prompted. DJI GO 4 displays a warning when the battery level is low. The aircraft will automatically return to the Home Point if no action is taken after a ten-second countdown. The user can cancel RTH by pressing the RTH button or Flight Pause button on the remote controller.

Note: this function is intimated specifically so the drone has enough battery to come back to you, so if you cancel it, make sure you know what you’re doing.
The function can not be overridden if the drone only has enough battery to descend from its current altitude:

The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude. The user cannot cancel the auto-landing but can use the remote controller to alter the aircraft’s orientation during the landing process.


The earliest recorded use of a UAV for military use was in July 1849, but if we include non-military UAVs, was there anything earlier? The history of drones Wikipedia article starts with the Austrian incendiary balloons of July 1849 as the first recorded use of UAVs for the military.

Was this the earliest record of any UAV, whether for military use or not?

I have recently written a dissertation on non-military drones and the first mention that I could find for what we would consider modern drones used in a context other than direct military action was when, in 1994, they were used as overhead surveillance for NATO envoys in Bosnia.

In terms of any UAV, not necessarily guided aircraft, the incendiary balloons are the earliest example I can think of, however, carrier pigeons were used as early as 1150 according to Wikipedia, so this may qualify.


Does the Ryze Tello have an adjustable camera angle? With the pictures I've looked at of the Ryze Tello, it seems that the camera is fixed and cannot look straight down, such as with the DJI Mavic Air 2. Does the camera have variable angles, or is it fixed-angle?

The Ryze Tello has a fixed-angle camera and is not adjustable (without modification). There are, however, a few ways to get pictures at different angles. The first way is to accelerate to get a downward camera angle or to go backwards to get an upward angle with the camera. This method is great if you don't want to modify anything. If you want a permanent adjustment to the camera angle and you don't mind modifying the Tello, you can follow the instructions here to modify the camera position.


Can I configure Betaflight in the field without using a laptop? I often find myself wanting to make adjustments to the settings on my quadcopter in the field, especially when tuning PID settings and rate profiles. I currently bring a laptop with me wherever I go so I can plug in over USB and use the Betaflight configurator, but it's very annoying to keep with me when I go fly.

Is there any way I can edit the settings on my Betaflight quad in the field without using a laptop?

Yes, you actually can! There are a couple of options for the Betaflight firmware which are mostly plug and play.

OpenTX Lua Scripts

Radios running OpenTX can use scripts written in Lua to control these parameters with the radio's scroll wheel and buttons. Please see @PaulKendall's answer for an explanation of how this method works.

Betaflight OSD

If you have an FPV setup on your quad, you can make use of the Betaflight OSD to tweak the vast majority of settings you would need access to during a flight session, like the PID values and rate profiles you mentioned. The OSD makes use of the sticks on your transmitter to navigate the menus, which appear as an overlay on top of the camera feed from the quad.

As described in this article by Oscar Liang, the stick combination mid throttle, yaw left, pitch forward, roll centered is used to enter the menu, which should look something like this:

From here, pitch up/down is used to navigate up and down in the current menu, and roll right to select an option or enter a sub-menu. (items with arrows on the right side are sub-menus) The roll axis is used to change a value up/down.

I know this sounds confusing, but it makes a lot more sense once you try it out and gain experience working with it. Remember to select the SAVE REBOOT after making a change and before going back to flying, or your change likely won't take effect!

Speedy Bee Smartphone App

If you want an experience that is closest to using the desktop Betaflight configurator or don't have an FPV setup on your quad to use, the Speedy Bee smartphone app for iOS and Android may be a good option. You can connect to the quad either using Bluetooth (you must have a Bluetooth module already installed on your quad), or over USB (USB OTG mode is only supported on Android).

Because this app is developed and maintained by a third-party and not the Betaflight project, some new settings aren't likely to be accessible with this app, but it should work for most common settings. I suggest watching Joshua Bardwell's video about this app for more details.


What blocks an FPV video signal? I am interested in long-range range FPV flying. What things block the video signal of a 5.8gHz video transmitter the most?

Just about anything will block/interfere with radio signaling if there's enough of it in the path between the transmitter and receiver or in the immediate vicinity of them. (sometimes referrred to as the Fresnel Zone) However, these are some of the most notorious offenders:

Tight spaces with a lot of multipath interference
Concrete and brick structures
Bodies of water
Soil and earth
Large structures
Forests and large amounts of trees
Lots of human bodies
etc.

One could go on forever listing out different materials, but these are some of the more common items to encounter for FPV.

In general, the rule is to maintain as much line-of-sight as possible between the transmitter and receiver. This is true because obstacles will force the radio waves to take indirect paths, bouncing repeatedly off of stuff until it hits the receiver antenna. Multipath interference comes from this, because often many different (multi)paths will converge on the receiver at different times and cause interference with each other, distorting the image that your goggles/FPV receiver will pick up.


What are 'Modes' of a transmitter / controller? I have heard a lot of reference to the 'Modes' of a transmitter/controller.

What is the Mode of a remote controller, and what is the difference between them?

The Mode of a transmitter refers to which stick on the transmitter controls which movement on a drone. There are 4 modes (named Mode 1 to 4) but the most common are Mode 1 and Mode 2.

The image below shows which control is associated with which aircraft axis, for each mode. The black text refers to fixed-wing aircraft and the blue text is the multirotor equivalent.

Mode 1 and 2 are the most common flight modes used.  Most multirotor pilots fly mode 2 (although there are exceptions, one of the OG FPV pilots FinalGlideAus notably flew mode 1).  Almost all "toy" multirotors are Mode 2.  In fixed-wing RC mode 2 is very common in the US, while Mode 1 is popular elsewhere.

When starting out, find out what mode the people you're likely to fly with use.  Having a more knowledgeable pilot being able to fly your drone, or being able to watch their fingers and see how they're doing a particular trick, or for them to be able to coach you easily is enormously beneficial.  Once you're comfortable, if you want to explore the other modes, and see if something else feels better, then go for it.  If you don't plan to fly with anyone else and have no strong opinion, go mode 2.  Virtually all of the stick cam tutorials you'll watch online are mode 2.


What should I keep in mind when picking my first drone? While I don't know much about drones yet, I've seen people use them to make awesome photographs and videos, and I want to be able to do that too.

Since I've never flown a drone, I'm looking for a drone that I can use to learn how to fly, it should probably also be able to hover. I like seeing the videos of drones that fly very fast or avoid obstacles with seeming ease. I'm not planning on sneaking up on wildlife, so it doesn't have to be very quiet.

I've been wondering if my first drone should include some camera equipment already or not. If I crash and break a camera, that might be an expensive crash. But if I don't include a camera, how am I going to judge whether I've learned to fly a drone in a way that can capture nice pictures/videos?

I've seen drones being sold in places like toy stores, electronica shops, and specialist shops. There are huge differences in price ranges, and of course in what these drones can do.

But even with the above in mind, I have no idea how to pick a good beginner's model from all of them. What do you keep in mind when picking your first drone, to practice flying and photography/filming with?

An important first step to take when getting into drones is learning to fly them. The very first drone I would recommend to someone is a cheap drone that can be used to learn to fly. It can be disheartening to buy an expensive drone only to crash it and have lost hundreds or thousands of dollars which is why learning to fly with a cheap drone first is a good idea so you can master the skills of controlling the drone. Your very first drone should be any drone cheap enough to not feel bad when it crashes. The Eachine e010 is a basic drone you could learn to fly with.

If you are looking to get into making videos with drones there are two major types to consider: Freestyle/acro drones or professional video drones. The videos you see of drones going really fast, avoiding obstacles, and doing stunts are high-performance freestyle or racing drones. Videos of scenes and landscapes are often from drones designed to carry a professional camera and are used to get extremely steady, smooth videos.

If you want a relatively inexpensive freestyle drone I recommend the iflight Nazgul5 or iflight Cidora SL5-E because it is a quality drone that performs very well for a very reasonable price. This drone has a camera on it for FPV but a GoPro would be needed to make good quality footage.

A good inexpensive camera drone that comes with a stabilized, quality camera is the DJI Mavic mini. It is not too expensive and it is light enough to not need registration. After that, there are many more good camera drones that are more expensive.


How to keep my prop from flying off my motor? After finally getting every piece on my plane to work, another piece decided to be a problem. Great.
My problem is pretty much already summed up in the title, my prop keeps flying off my motor, and I want to stop it from doing that because no prop pretty much means you crash.
Here is a picture of the motor pod and prop unattached from each other.

Here is a picture of the prop hardware that goes over the motor.

Sorry if the pics aren't working, I don't use them a lot and haven't quite figured out the syntax and stuff. Any suggestions on how to keep the prop on during flight?

It looks like you are missing a piece of the prop adapter.
There should be three pieces, the nut, the central shaft with a thread for the nut on one end and a taper on the other, and a collar that matches the taper. You're missing the collar.
The nut forces the collar onto the taper, which squeezes the slots together, gripping the shaft. They're normally very secure but won't work without all three parts.
Here's a picture (I get an error when I try to embed it) or you could just look for pictures of 'collet prop adapter'.
https://shop.pichler.de/Collet-Cone-Prop-Adapter-60mm


What Requirements Do I Need to Comply with in Order to Fly a Custom Drone Commercially in Texas I'm currently in the process of selecting parts for use in both a quad and VTOL flying wing drones. Both drones are going to weigh over 250 grams but I don't know what the total weight will be yet although they will both be under the 50 pound or so limit the FAA has in place. The quad will be used for photography while the VTOL will be used for cargo carrying packages up to 40lbs and the VTOLs total weight with cargo will not exceed the 50lb limit. I know I'm probably going to need a license but IDK which one or if I'm going to need more than one. Also, I just want to fly a freaking drone without giving all of my personal info away to the government. Is there any way I can obtain a FAA license without having to provide a photo ID? I know a little bit about the registration process but tbh, my info is several years old and it's very confusing. I live in Texas if that has any relevance to the regulations. If there's anything else I should be aware of regarding registration in general or requirements for the drone itself then please feel free to share. Any assistance would be greatly appreciated. Thank you :D

In general Drone is considered as UAS (Unmanned Aircraft System)
The FAA has basic information on their website https://www.faa.gov/uas/
In order to fly the drone, the drone need to be registered it cost US $ 5 for 3 years.
and for personnel flying the drone need to have adequate knowledge on regulations, procedures including map and charts, notam, etc if you intent to operate commercially then Part 107 of US FAA regulations applies.
For carrying goods especially cargo,  as far as airmen certification personnel detail is required, although picture is not displayed in the license however for security reason personal details including address is required.  see the license information here  and official FAA page for license registration, the FAA is cover for all United states, including Texas.
I hope this help


FPV camera and beeper seems to be interfering with each other I recently changed my VTX from the Tbs unify pro 5G8 HV to the unify pro 5G8 V3. Because of this I had to move the cameras 5v input from the VTX to the FC (The HV model has a built in regulator, and the V3 doesn't). I also mounted the VTX on a 5v output on the FC instead of vbat.
Now to the problem: When I turn on the drone everything is fine until the beeper beeps once. This causes the cameras image to go gray momentarily.
When I then turn on the transmitter and start the beeper shortly, it never turns off, it just starts beeping with shorter and faster beeps. This also causes the camera feed to go gray.
My hypothesis is that the 5v regulator becomes overloaded since all peripherals are connected to 5v. Could this be correct?
I should also mention that the OSD is visible at all times, so the problem is definitely with the camera and not the VTX. The FC is a HobbyWing Xrotor fc f4 g2.
Update: I desoldered the beeper, and the camera image still becomes partially gray, but only when I turn on the transmitter.

The problem was indeed the 5V regulator. I bought an external 5V 1.2A regulator and hooked up the camera and VTX to it, and all my problems have disappeared.


Control opentx transmitter from pc? is a standard way to control a physical aircraft by connecting a frsky transmitter to a PC?

I do NOT want to use the transmitter to control a flight Sim etc.

I'd like to write autopilot software myself, and have it running on a PC. Id like to connect the PC to the transmitter, and have it send inputs to the aircraft, and also send telemetry back.

I'd rather not use an ardupilot.

Anyone have a link to details of someone doing this before?

Tldr: can I use a keyboard to control an aircraft with a frsky transmitter?

OpenTX can be built from source for your receiver using various compile options which may be useful.

Enabling USB_SERIAL and CLI will allow connection to your pc using a serial connection, which you can use for bidirectional communication.

You will need to add code to the OpenTX firmware to accept commands from the pc, to control the radio. It may be simplest to utilize the trainer variables to control the outputs.

The changes required are:

in cli.cpp, connect the serial to the trainer variables:

int cliSet(const char ** argv)
{
  if (!strcmp(argv[1], "trainer"))
  {
    int thr;
    int chan;
    if ( (toInt(argv, 2, &chan) > 0)
       &&(toInt(argv, 3, &thr) > 0))
    {
        ppmInput[chan] = thr;
        ppmInputValidityTimer = 240;//PPM_IN_VALID_TIMEOUT;
        serialPrint("!");
    }
  }
  ...cliSet continues
}

in mixer.cpp, enable all trainer channels by default:

// comment out this check
//        && isFunctionActive(FUNCTION_TRAINER_STICK1+ch)

in trainer.cpp, clear all trainer signals after timeout:

void checkTrainerSignalWarning()
{
   ...
   else if (!ppmInputValidityTimer && (ppmInputValidState == PPM_IN_IS_VALID))
   {
      ppmInputValidState = PPM_IN_INVALID;
      AUDIO_TRAINER_LOST();
      memset(ppmInput, 0, sizeof(ppmInput));   //clear all trainer inputs
   }
   ...
 }

You should then be able to use commands over serial such as:

set trainer 1 500

to control channel 1 to a value of 500


Can I use two 2s lipo batteries to power my FPV DJI goggles? The FPV DJI goggles can take 7.4-17.6 Voltage. I am using a 2S 3000mAh LiPo battery. My plan is to buy another of the same liPo battery and attach it with a female to 2 male TX60 connector, making it a 4s lipo battery of 3000mAh(14.8 - 16.8V) .
Do I need to consider anything else?

Connecting the batteries in series or parallel brings two new issues with it that you need to consider before you start using them and they are both related to batteries that are not on the same charge level.

If you put two batteries of a different charge in parallel, the battery with the highest charge will charge the other one and very high currents can flow which can damage your batteries.
If you put two batteries of a different charge in series they will both discharge at the same rate during use and the battery with the lowest charge will discharge a lot deeper potentially causing a lot of damage.

So if you want to do this always take this into consideration:
Parallel connection: Make sure the batteries are at the same charge level.
Series connection: Make sure the batteries are at the same charge level AND of the same capacity.
So if you want the higher capacity and don't necessary need the higher voltage (in this case you don't): parallel connection is better and safer than in series.


Drones to fly indoors Due to the current situation, I can't go outside to fly my drone. What's a small and easy to control nano drone I can fly indoors (no camera necessary)? It should be easy to control as I don't want to crash into anything but don't want to give up drone flying altogether.

This depends - do you want to fly FPV or LOS, angle or acro?

For the LOS angle, I absolutely love the Hubsan X4 H107C. It’s relatively cheap, flies smoothly and is really robust. There is also a version without a camera called the H107L.

If you want to fly FPV acro (or angle), the Tinyhawk, Mobula 6 and Meteor 65 (though you may need a throttle cap) are all said to be very good.


Is Naze32 capable of autopilot? (Assuming that you have the required telemetry hardware, barometer, etc...) Are any versions of the Naze32 capable of autopilot features, such as altitude hold? How about more advanced things like flying a preset path? If it's relatively simple, how?

You'd likely be looking to run a firmware like iNav on your flight controller to enable the path-following features you need like altitude hold and mission/waypoint flying. This is really the most capable and readily available autonomous flight firmware for hobbyists.
The Naze32 FC board is based on the older and less capable STM32F103CBT6 processor (cit.), which hasn't been supported in iNav since the 1.7.2 release in July 2017 because the pace of feature development outstripped the computational power of the STM32F1xx processors.
Although you wouldn't be receiving feature/bugfix updates for iNav running on the Naze32, you would still have access to the features added prior to the 1.7.3 release that dropped support for F1 boards and almost certainly includes some sort of altitude hold and waypoint following capabilities, even if they're more rudimentary than what is available in the latest versions of the firmware.
You can install and configure iNav using the iNav Configurator and by reading the getting started documentation on the iNav wiki pages.


What is a ground loop and how does a common ground reduce video noise? To reduce video noise, it is often recommended to add a common ground between VTX and camera to avoid ground loops. What is a ground loop, how does it add video noise and how can a common ground negate its effects. Thanks.

If enough current flows and two ground pads are far enough apart, there might be a voltage difference between them because of the resistance in the PCB:s traces. That's called a ground loop.
As for why that causes noise; if the camera and the VTX have different reference points, a signal sent from the camera won't be received correctly by the VTX, and since a PAL or NTSC (The types of video that is used for analog FPV systems) signals use less than one volt, even a small in potential can cause video noise that will appear as horizontal bars moving vertically.
Here is an some more information if you would like to read more about it


Are there any alternatives to BetaFlight? I wonder if there are any alternatives to BetaFlight. If there are any alternatives, what are their advantages and disadvantages?

Among open-source options, Emuflight, INav & Ardupilot (different focus) Butterflight (mostly defunct), Raceflight (mostly defunct).  There is still Cleanflight and Baseflight, which are the shared lineage for Betaflight, Emu, Butr, and others.
Of these, EMU has an EKF (Enhanced Kalman Filter) variant of filtering, and also in older releases captures a lot of the 'goodness' of BF 3.5.7 filtering with a few PID adjustments that some pilots prefer for feel - and is now where Project Mockingbird does custom whoop tune development.

FlightOne, especially FalcoX adds a lot of ease of use for OSD configuration, and on most setups the stock tune out of the box or selected from a short list of defaults will fly really well.  Require FL1 FC or FL1 license on specific F411 targets (at the moment) - FL1 makes great ESCs if you can get ahold of them.

KISS is also a closed source, with mostly one source of ongoing development, but provides impressively good flight performance as well.  Needs KISS FC to work, I do recommend other ESCs.

For closed source options, the biggest downside is cost and need to re-learn some of the approaches if you're familiar with Betaflight already.

The biggest feature-set of Betaflight lies in the RPM Filtering capability (which in my experience can make cheap builds outperform most people's expensive stuff), although for many users without a background that makes the tuning process very accessible, the 3.5.7 builds of BetaFlight will fly better in stock or near-stock tunes.