Gunny's Concept of E-Flite L-13 Blanik

[gunny11]

Gluing flap tracks into position

[gunny11]

Gluing in the horns

[gunny11]

marking the wing for the sockets

[gunny11]

cutting slots into wing

[gunny11]

and for the horns

[Mark9]

Very ambitious project and excelent implementation. One nice side benefit of proper Fowler flaps is the effective increase of the wing area when deployed. May be hard to see that in other than a full scale though.

[Slope440]

Hello Gunny11

Ive just been looking at your flower flap design details and have a question. I’m designing something similar and have decided I need a servo driving each end of the flap to avoid binding. Are you using two servos? If not, how does the design avoid binding caused by the potential for the two ends not moving exactly the same way?

thanks

[gunny11]

Hi,
thank you for your inquiry... Very good question! Just like the full size Blanik, it has 2 motion transfer arms connected to a torsion tube. So, to answer your question, yes... you must have two pushrods, one at or near each end to avoid binding. It's easier to use two digital Hightec programmable servos so you can fine tune both ends and mid points of the servo travel with a programmer. Or you can use a "match box" device.
However..... It can be done with one servo.

[gunny11]

I see I never finished this thread.

[ARUP]

Gunny... that is one bad @$$ sailplane!

[Slope440]

OK. Your'e using a torque tube. I've modified HS81 servos for continuous rotation by moving the feedback pot outside and using a "lead screw" (it's just a bolt) arrangement to enable a 2" linear travel. A traveling nut drives the flap "push out rod" and the feedback pot also. Was planning out having a linear servo at each end but it's becoming a problem. Ideally I'd use 4 Tx channels (one for each servo) but my Tx is maxed out at 6 channels. I've "Y'd" the servos together for now but its difficult to get them calibrated so they both move exactly the same.

What is the "match box" device? A commercial product or something that would be home made? I've not seen one of those for sale anywhere.

Thanks

[Steve P]

JR Matchbox... http://www.jramericas.com/83783/JRPA900/

[Mark9]

Another device you might look at is the Equalizer II. Many guys use it to run multiple servos on IMAC surfaces. They have a version that can run up to three from a single input signal. Use one on my Blanik when I could not find a way to run dual servos on the elevator and do what I wanted with the flaps...maxed the channels too. So, there are multiple options out there.

http://www.smart-fly.com/equalizer-ii

[JimD]

The reason Gunny never finished the thread...

[Slope440]

Hey....I like the JR device! Looks like just what I need!! Thanks!

[gunny11]

Lol Jim, for some reason... I knew you would do that.
I guess I have to spill the beans... I'm very active in another forum!

Uhhh, a John Deere tractor forum. Been very very busy designing and fabricating new inventions. I'm up to 99 mods.
i like playing with waterjet cut 1/2" thick steel parts that I designed and watch them come together.

[gunny11]

Slope440, I actually use the two servo method per flap. Just easier...

ok, gotta go back to my tractor forum... LOL

[Mark9]

Gunny you're a master! Like the shot of the Blanik in the air. Is that full extension?