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Can i auto takeoff my easystar-II from the grass?


(Am) #1

Hi all,
Please advice me if i can do auto takeoff from the park grass using arduplane?My plane doesn’t have a tail wheel.Just ailerons and rudder and it takes off okay in manual mode from its belly.It has enough power to take off from the grass.
But it would be nice to have auto takeoff as sometimes its hard to point it straight while taking off using manual mode.Thanks.


(Hunt0r) #2

You should look into hand-launched auto takeoff. That will be more reliable and much better than belly-takeoff for this plane.

I hand-launch auto-takeoff with EasyStar2-like planes often, it works great.


(Am) #3

Thanks for your reply hunt0r.
The only thing i am worried about hand launching this plane is its thrust line of the motor.It tends to nose dive to the ground if more than needed power is applied during take off.It has to be a good combination of enough throttle and elevator.Do you think arduplane will manage it automatically?I have no previous experience with it:(


(Hunt0r) #4

Yes, ArduPlane will handle that just fine. The EasyStar2 is an excellent auto-takeoff platform, when configured correctly.


(Am) #5

Okay,that’s great .Sure I would like to try out hand launch then. Could you please guide me what parameters i should be focusing on for hand launching easystar?Thanks


(JHI) #6

I agree with hunt0r.

Here is a compilation of ordinary hand launch and AutoTakeoff from my first fligthts with a similar plane - the Bixler 2.

After a lot of missed, and near missed ordinary hand launches (I am a bad thrower), I decided to try AutoTakeoff, and the succsess rate went up to almost 100%! Always best results with a little head wind during launch, I remember a few missed takeoffs trying to take off downwind :unamused: - see 6:08, the 14th takeoff…

The cause of the crash at 5:16 was a loose elevator servo plug, not related to Mission or AutoTakeoff.

Happy takeoffs (and landings)!
-Jan


(Hunt0r) #7

Read the hand-launching instructions here: http://ardupilot.org/plane/docs/automatic-takeoff.html

Those 4 parameters are key. Also, the page provides other crucial info: launch INTO the wind, and remember that the aircraft will track the compass heading which was set when the AUTO mode was engaged.

If you feel it is safe, because the EasyStar prop is mounted high and I was throwing overhead, I had the propeller turn on full-throttle BEFORE I threw. But, I have also had successful auto-launches with non-zero min_acc, minspd, and thr_delay. Whatever you decide, make sure you do it safely.

One mistake NOT to make: Turn on AUTO, then decide to toss in a different direction because the wind shifts, or something. Don’t do that.


(Fnoop) #8

Why is this bad idea?


(Hunt0r) #9

My understanding is that when you turn on AUTO, which begins auto-takeoff, the airplane locks its current heading as the desired takeoff direction. (For example, let’s say it locks in East.) If you then turn and toss, the aircraft will attempt a sharp turn near the ground. (Say you toss South, because a wind gust comes from the South. The plane will attempt a 90deg left turn near the ground, attempting to takeoff to the East and this is very detrimental to takeoff performance. It may cause an immediate crash.)

If I’m wrong about this, let me (and others) know!


(Am) #10

I am not using Compass from my ublox GPS on my fixed wing.Will it be still okay? Thanks and I will go through the documentation.


(Hunt0r) #11

Are you using any compass? If not, I have no idea how auto-takeoff would work… so proceed with EXTREME caution.


(Am) #12

No I am not using any compass at all.I read that on fixed wing you don’t need any compass.


(Hunt0r) #13

I do not know how well Auto Takeoff will work, then. Proceed at your own risk.

Does anyone else know?


(Fnoop) #14

I don’t know if this is the case, but I would have thought it would be safer for it to take off in the direction thrown, get to target height and then start it’s turns. I had many problems with auto launch, maybe this was one of them.
@tridge, sorry for the basic question but could you please confirm what the behaviour is/should be?


(basti) #15

GPS is used for yaw alignment if there‘s no mag. it works perfectly well, i‘m not using a mag in fixed wing setups. EKF yaw will align as soon as you have a GPS velocity vector, that will be like a fraction of a second after you launched. auto start locks the initial yaw until start is completed, so your plane won‘t attempt a sharp turn before start altitude is cleared.
autostart works perfectly well with default parameters imho.

cheers, basti


(Am) #16

Thanks Basti for the info.
I would like to try hand launch.Do I have to use mission planner every time I do hand launch?

Could you please guide me how to setup auto hand launch?

I have already set the parameters as per the docs except the auto flight mode.I wasn’t too sure about the auto takeoff command.Where to enter that command? Thanks.


(basti) #17

the documentation on automatic takeoff is quite comprehensive and it’s really worth reading carefully.
in short terms you need to set AUTO as one of your flight modes and program a mission with the TAKEOFF command as first mission item at least. this command is not bound to absolute coordinates, so you can use a mission containing only this item for auto takeoff regardless of your location, not requiring GCS connect. having a GCS connected on first attempts does help a lot if you meet issues though.
in the video linked above i did the autostart entirely on defaults. this means the motor will start as soon as the flight controller is armed and flight mode is set to AUTO, ready to throw. check the docs on how to set an acceleration threshold and delay to meet individual takeoff preferences / requirements.

basti


(Am) #18

Thanks vierfuffzig for the guidance.Will try it soon.