Help with GP Decathalon

Hi Guys,
I bought a GP Super Decathalon with both eyes wide open.
My plan is to whip this P.O.S. into a model airplane. This model, like
so many other GP Decathalons, lands like a bag of bricks. If you drop
your landing speed slightly under the speed of light, it immediately
snaps to the ground.
My plan of action is to expose enough of the ribs to saturate the wing
stucture with water and ammonia so I can induce washout. Bold plan,
eh?
Any suggestions as to how much washout?
What kind of incidence should there be? Any chance of corrective
incidence to counter the snap effect?
Any good ideas to correcting washout? Can I add to to the outer wing
panel instead of trying to reshape the existing structure?
Comments from owners of GP Decathalon are welcome.
Thanks,
Roy
Reply to
Roy Myklebust
Loading thread data ...
Roy --
Before you go to drastic measures, tow things come to mind. First is to check the lateral balance of the model. Next is a possible, and easy attempt.
Add some small "Stall Strips" on the leading edge of the wing near the fuselage. By this I mean some "V" shapes about a half an inch on a side by about six inches long. These could be folded manila card stock simply taped to the top and bottom of the leading edge temporarily. The 'point' of the "V" goes forward of the center line of the leading edge. The purpose of these is to get the inboard portion of the wing to stall first (before the tips), which will still leave you with aileron control. Many aircraft have them installed, including the Beechcraft Bonanza.
Let us know what your solution is.
Cheers -- \__________Lyman Slack_________/ \______AMA6430 IMAA1564___/ \____Flying Gators R/C______/ \__Gainesville FL _________/ Visit my Web Site at:
formatting link

Reply to
Lyman Slack
I used a different material than Lynam. Triangle stock set up so that the LE was flat for the inner 6 inches of the wing. Tape them on and move them around until you find the location that works best. You also NEED to do a lot of high altitude slow speed work so that you can recognize when it is about to stop flying.
-- Jim Branaum AMA 1428
Six_O'clock_High Target snipped-for-privacy@Guns.com
Reply to
Six_O'Clock_High
You identified the main problem right there...it's too heavy. CAUTION: I've also seen this plane enter a spin and never recover. Dr.1 Driver "There's a Hun in the sun!"
Reply to
Dr1Driver
Roy,
Although not familiar with his particular model, you describe a plane that is typically too heavy. (reminds me of my old Sig Kobra after a few "repairs").
I assume your first course of action will be a serious attempt to lighten the plane before you start experimenting with the wings.
-Bill
Reply to
Bill Archibald
"Roy Myklebust" -- You asked me for some more information, however you did not include a valid E-mail address. If you want an answer and a sketch, send me another note with your address.
Cheers -- \__________Lyman Slack_________/ \______AMA6430 IMAA1564___/ \____Flying Gators R/C______/ \__Gainesville FL _________/ Visit my Web Site at:
formatting link

Reply to
Lyman Slack
Roy,
I agree with the sentiment. I 'inherited' one and have been struggling to master it. I have read that 3 degrees of washout will help. I have learned to approach moderately slowly and by using a real slow idle, to lose speed just at touchdown. I'm now landing in the first 1/4 of the runway and staying on it! Slow approaches take practice at a high enough altitude to recover from the deadly snap (400 feet?). It has suffered 2 major crashes from previous owner from the #$%^&*@ snap. If you are using coupled aileron/rudder, turn it off. Stay off the ailerons as much as possible when landing.
Good luck bending that wing,
Bob
Reply to
Robert Thornburg
I also read that bulletin. I would not move the gear back. It is already touchy on takeoff. Reducing weight would also help.
Bob
Reply to
Robert Thornburg
Well I purchased the GP decath kit about 4 years ago, Its taken me 4 years to build it, ( this and 70 other projects, you know what its like) I havent covered it yet, I altered the wing by changing to Barn door ailerons, and I am following this thread with great interest. The only plane I've had that tip stalled was a Old Timer Trenton Terror, even with that wing incidence on the final approach if you tried to slow the plane down by lifting the evevator even a little bit the wing would drop and into the ground nose first Regards Wayne I'm not a MD so remove to reply off group
Reply to
Wayne Bourke

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.