I’m trying to determine the maximum forward flight speed of my custom copter in a controlled manner. I’m not super comfortable with my FPV skills to manually fly it at full throttle, so I’d like to do an autopilot flight. I’ve autotuned the vehicle and feel pretty good about doing autopilot flights.
What would be the best approach to plan a mission which flies the copter at maximum forward flight speed?
Read thru this thread for some pointers. Unfortunately the links to my logs are broken but there is still valuable info there.
High Speed Auto Mission
You have to start with a very well tuned craft then set Angle max to 80deg and go for it! Well, work up to that if it makes you more comfortable. My 2 craft ran out of power, it wasn’t a limitation of Arducopter. Start with there-and-back Missions with enough distance between waypoints to maintain stable speed for a bit.
Also, use search here for TEKNOFEST. Our friends from Türkiye on the forum here were really winding the craft’s out for that competition!!
Thank you @dkemxr for the references, this helps a ton.
Just to confirm, ANGLE_MAX would be set in the params list and the speed target would be set with the DO_CHANGE_SPEED command in the flight plan - correct?
Yes. My speed runs would have a take-off command and a close Waypoint at default speed (WPNAV_SPEED). Then a DO_CHANGE_SPEED command for speed to a Waypoint a few km away or whatever your battery can handle. Then a WP back near the 1st and another DO_CHANGE_SPEED to slow it back down before a LAND command. Or, you can use a Chan 6 In-flight-tune option on a Tx pot and change it anytime but I would automate it 1st while testing.
I’ll be honest, even with my test mule quad it’s a nail biter at 1st 
Got it - thank you @dkemxr !!
Do you know if record max flight speeds for 5", 10", ect quads are published anywhere? Looking to push the envelope and compare the performance of my vehicle. I see some of the results on the thread, but not sure how this compares to all time records.
And according to your post you are using ArduCopter 4.0.x
Make sure to update to ArduCopter 4.3.4-rc1 before doing any tests.
No, don’t think so. Just the occasional inquiry like yours that put’s these efforts back in the lime light! For the 2 craft I tested with, a 4&5" it was ~40 m/s. But certainly with a higher thrust/weight ratio it will be faster.
@dkemxr and @andyp1per Would be curious to know what your hardware setup is for the flight controller, telemetry radio, gps, and frame.
MatekH743 Slim
TBS Tracer Sixty9
Matek M8Q-5883 and then M10-5883. I have an unconfirmed suspicion that the latter generates bad horizontal speed errors while the former does not have good vertical height accuracy. I had two flyaways doing this experiments and they all appear to be GPS related. Tridge and I are discussing using DCM as a fallback to prevent this
Armattan Marmotte 5"
I actually did a video on the setup - Introducing the Beater - YouTube
Got it, thanks for the heads up on the GPS.
Apologies If I missed this in the video, but what telemetry system are you using to communicate with the ground station? Or is it built into the FC? Most of my experience is with the pixhawk controllers, which use an external telemetry radio. Thanks.
Using CRSF (so TBS Tracer Sixty9) and the yaapu widget into my OpenTX transmitter. Obviously the telemetry is limited but I generally find it enough. It even has map support. There is wifi support in TBS TX modules and its supposedly better these days, but I have had problems with it in the past.
A mix of hardware. Old Pixracer on one, A Kakute H7 on another, a Matek H743-Slim on a 3rd, Mini version on 4th. The Matek M8Q on all of them. Some Frsky R9, Some TBS CRSF. Tx telemetry only (Yaapu). The Nano Rx Pro version of receivers has good return telemetry range with more transmit power.
I haven’t tried returning to TBS WiFi either, it didn’t work well for me but some claim it’s working now as Andy said. That will transmit telemetry from the Tx module to a Ground station.
FYI, i tried a max speed run with my 3DR Solo. The Solo had no camera or gimbal. My plan was to fly in acro mod like it was an RC plane. Then switch to loiter mode so the craft could recover. The craft tilted too much, lost GPS signal, and did not recover before trimming the trees. Nothing was hurt. Flight log indicated 99mph (may not be accurate). Should have switched to manual mode.
Good luck with your test. I’ll enjoy following your progress.
Have you tried shielding the gps harness? That seemed to help some folks
It’s not the cables, it’s the GPS antenna. You can’t tilt 80 degrees a ceramic bric antenna without its groundplane obscuring half the sky. Not to mention that any ceramic smaller then 35x35 mm will have a hard time covering both GPS and GLONASS bands, and if you don’t like staring at the sun, your runs will be mainly northwards-ish so that groundplane obscures probably 3/4 of the GNSS constellation.
Probably a helical antenna would save the day.
I have been considering mounting two, one at 30 degrees and one at 70 degrees to see if this helps. Helical not very crash friendly 