Auto Take off Mode Without compass?

[Allister (Allister Schreiber)]

Rather than derail another thread I thought I’d start a new one. And please don’t mistake my tone, I’m not trying to prove anything. I’m only trying to learn something. (easier said than done some days…)

@VRquaeler

Most of the time I use Auto take off as part of a mission in “auto” mode. Back in the days of AP3.9.xx versions the option of AutoTakeOff as flight mode was not available. I kept using the old way. It just works for me.

Takeoff flight mode vs. takeoff in a mission, Plane 4.0.6 - CLEARLY DIFFERENT!

Hi folks. @vierfuffzig has posted an issue for developers to track the TAKEOFF Mode vs Auto Takeofff behavior: Regarding the turn on launch, this is actually a long standing problem. It comes from not relying on heading-lock instead of GPS ground/heading track due to it not being reliable yet and thus relying on gyro and compass which take a nasty G-shock and current/magnetic spike at full-throttle on takeoff. I have a pull-request that I posted a few months ago to address this (for auto ta…

I’m interested to learn how well Plane will take off in Auto-take off MODE without a compass. It’s proven that it will work in a mission, but the thread above clearly shows that take off mode and mission are not the same. I’ve been under the impression that for auto-take off MODE (not mission) you need to have a compass, and maybe I’ve misunderstood but I think the comment below suggests that:

@MagicRuB

Regarding the turn on launch, this is actually a long standing problem. It comes from not relying on heading-lock instead of GPS ground/heading track due to it not being reliable yet and thus relying on gyro and compass which take a nasty G-shock and current/magnetic spike at full-throttle on takeoff.

This suggests to me that if you don’t have a compass, you’re totally relying on the gyro for heading during take off. But what happens when the controller does figure out what direction the plane is actually going? In another thread a poster was saying he could have a 90 degree difference between the planes reported heading vs the actually heading, so this correction would be significant. Will the plane maintain that “new” heading or will it try to correct to back to the “original” heading? If there is a correction shouldn’t TKOFF_LVL_ALT keep it from happening too soon?

If you are using auto take off mode without a compass would it be a good idea to maybe be more generous with the TKOFF_LVL_ALT to keep things under control longer until the plane has more speed to deal with a larger correction?

I’ve used auto take off in both Mode and Mission, many times and I’m comfortable using it. But all my planes have always had compasses. No grand reason why, it’s just how I’ve always built them.

Thanks!

[UnknownPilot]

I just found this and wonder if I was affected by the issue recently: TAKEOFF Mode - first attempt with odd results

Too bad this has never received any replies, but it looks like enabling the compass might be a good idea in any case?

[Allister (Allister Schreiber)]

I use auto take off mode on my flying wings regularly. It’s been uneventful, exactly what I want in a take off. Maybe because of how I’m throwing the wing I’m a little more generous on what I expect my heading to be, as opposed to a wheeled take off, or more conventional hand-launched plane where the difference may be more noticeable. But I don’t think so. But like I said, all my planes have at least one (running) compass.