Comment by Wyliest on April 1, 2009 at 12:54am

I love this! Its simple and small. Can you post a some drawings of how to make it?

Comment by Bryan Cuervo on April 1, 2009 at 5:01am

Dean,
I see you're using a reflexed airfoil to help with stability about the Y axis. Is that enough for this wing planform in autonomous mode or do you get pitch oscillations? I really like the clear covering so we can see all the cool stuff and layout!

Comment by Noth666 on April 1, 2009 at 10:21am

Very nice one!!
What kind of flight times do you get?
I'm working on a MAV(foamie proto now) too - and I have 900mAh 2S lipos but they run out in a few minutes (2-3) to the motor cut point.

Moderator Comment by Jack Crossfire on April 1, 2009 at 10:48am

Make it statically unstable & use software rate damping instead of all that ball bearing rod stuff. You can do it. Must get myself some full size GPS rock solidity instead of the really small GPS.

Comment by Dean on April 1, 2009 at 4:54pm

The GPS is doing great with solid lock and 8-11 sats... no loss of lock. Glad I used the full size module.

Honestly, this thing flies like CRAP actually! I added 1 ounce of lead to the nose and it is managable in RC, but I couldn't get the PID gains to my satisfaction this morning in about 30 minues of test flight. The winglets help the lateral stability. Maybe Jack is right in that I should focus more on the D gains to tame the oscillation. RC flight wasn't so bad, so I think in stabilized flight the autopilot was adding problems with too high of P gains and over control.

Noth - my current draw is around 3-4 amps, and I was getting 10 minute flights today.

Jack - the requirement for the reflexed airfoil in a plank airplane is to get the C.G. seriously far forward, as in 10% from the LE. Putting that 1 ounce motor in the back (not using the carbon shaft) would really screw up the C.G. even further. Right now I am not at 10% C.G., more like 20%, which is why I think this is so unstable. Based on what I saw today and the minimal effects of twiddling with PID gains, I can't imagine putting the motor in the back.

Moderator Comment by Gary Mortimer on April 2, 2009 at 2:42am

Next time why not sweep the plank forward?

Although I realise it would'nt be a plank then.

Comment by Matt on April 2, 2009 at 11:10am

Nice construction! I'd recommend not worrying about the derivative gain (turn it to zero) and turning down your proportional until it stops oscillating (I'm assuming its a pitch oscillation your seeing). The loop speed of your autopilot / system (including pitch inertia, which is super tiny) will only tolerate so much gain.

Here is an IMU version, there are new videos up:
http://www.continentalctrls.com/

Comment