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Great Planes Super Decathlon 40 Kit HELP!!!

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Great Planes Super Decathlon 40 Kit HELP!!!

Old 06-18-2002, 10:29 PM
  #1  
thejetman
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I have built a Great Planes Super Decathlon 40 Kit. So far four take off's and four roll over crashes. On take off it rolls to the right or left hard and cartwheels. It is kind of a tip stall. I can't recover from it. It all happens about five feet off the ground. The stab is set to 0 degrees relative to the thrust line of the plane. Wing is set to 1 degree leading edge up all the way across the wing. I have set the eng thrust to -2 degrees and then again at +1/2. It has the 2 degree right thrust. I am using a MDS 48 with a 11-5 APC prop. The last crash took off the tail. If I can't find any answers I am going to trash the plane and move on. I have rebuilt it two times so far. Please let me know if you might have some help on the planes flying habits.
Thanks.
Keven
Old 06-19-2002, 12:09 AM
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caf2461
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Default decathalon

I will take a stab at this:
make sure you have enough air speed
balance the plane per plans
balance the plane laterally
set the aelerons to travel twice as much up as down this helps with stall and control
Old 06-19-2002, 01:58 AM
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crosswind
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I agree with all caf2461 said. Since you said it has rolled to each side I tend to think you may be yanking it off the ground too soon and perhaps at too steep an angle. It really sounds like the plane is stalling and dropping a wing. Also if the plane is tail heavy it could be very sensitive to elevator. You could be giving it too much up causing the wing to enter too great an angle of attack. This can stall a wing even at a normal flying speed. Check the balance (if you haven't already) and let the plane pick up more speed before you lift off. Ease it off gently without trying to climb out too fast. If it goes up okay, get some altitude and play with it some doing a few stalls at a safe height so you'll have a better idea of what to expect. In a nutshell, my bet is your plane is simply stalling. Hope this can help a fellow Okie!
Old 06-19-2002, 02:03 AM
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KingAirJockey
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I had one of these and it beat me up the first few times I tried to fly it.You've got to let it built up speed.Even though it has a large wing,the airplane is heavy and has alot of frontal area to over come to get flying.I flew mine with an os 46 fx for 3 seasons before selling it.It is not a floater by any means.
Old 06-19-2002, 11:19 AM
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wagas
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I've had one too, I liked mine buy I had to fly it like a rocket to keep it from Tip Stalling. Some advice from other owners in the past have been to either build wash out into the wing or I think you can crank up your ailerons to create washout also. Not quite sure I'm not an expert. I did enjoy mine and never had a problem with it. I had a TT 46 pro with 11 x 5 prop. I do agree with the above post, don't yank this airplane off the ground or try to bring it in slow. Keep the speed up......
Old 06-20-2002, 01:56 PM
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c1flyer
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I have built and flown this one as well. I believe there is a recommendation by Great Planes to build it with washout to reduce the tip stalling tendency of the plane. I have always liked mine once I got used to it. It is a handfull to take off and land in windy/crosswind situations. I agree with all of the statements made from set up to flying speed, as I had to incorporate all of these to be successful with this plane, given my skill level. You have to admit, once in the air it really flies and looks good!

Just my two pennies.
Old 06-20-2002, 03:15 PM
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MinnFlyer
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Default Great Planes Super Decathlon 40 Kit HELP!!!

My brother had on and demolished it on the first flight. The plane, as set up per the plans seems to be a little tail heavy. Try shifting the weight up front a little more.
Old 06-21-2002, 07:27 PM
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Default unstable???

I test flew one of these once. It was kinda unstable. The problem i noticed was once the plane started to stall the ailerons would become unaffective. Then once they have good air going over them again it would over correct it. If the plane starts to tip stall. Couple in alittle rudder with it and it will fly right out. DO NOT GET TOO MUCH RUDDER IN IT, or it will snap the opposite way it is stalling. I also have a midwest version. Its as gentle as can be. I would recomend that plane to anyone who likes decathlons or citabrias! They are wonderful airplanes! I wish you all luck and remember on takeoffs and landings better too fast, than too slow.

GeeBeeMan21
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Old 06-22-2002, 01:36 AM
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bipelover
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I don't think I can say anything positive for the Decathalon. I've got a friend that built the same kit and am sad to say that although the plane looked sharp on the ground that was all it was good for. It had a tendency to just quit flying on it's own. I've seen it fall from the sky at half throttle, quarter throttle, and only ever got to see it make a landing once. It had to be brought in HOT just to make it then. I've got and seen warbirds that didn't have to be brought in that hot on a landing. He finally decided to make a weathervane out of it. My advice is finish it and unload it A.S.A.P. Good Luck on whatever you decide.
Old 06-22-2002, 02:00 PM
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thejetman
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Default Going to repair the plane!!!

Hi all and thanks for all the input to my problem. I have decided to go ahead and repair the plane and try it again. I put all the parameters into the realflight program for the Decathalon. Moved the CG around and amazingly it did exactly what the real plane did with the CG moved back too far. I agree with the CG being incorrect on the plans. I contacted Great Planes about the problem and below is their responce...
Hello

Thank you for your recent e-mail.

Unfortunately, we are not aware of any poor handling characteristics with
this plane. If you could relay any more information on the building of the plane, we could try to analyze any possible problems.

I hope you find this information helpful. Should you have any further questions or concerns, please do not hesitate to contact us at this email address. (Please be sure to copy all previous emails into any future questions.) You can also reach our product support technical team at 217-398-8970, or via fax at 217-398-7721.

DID YOU KNOW that our web pages now all contain FAQs? (Frequently asked questions) Please drop by and take a look! We hope you'll find the information helpful and valuable to you.

Sincerely,
Tom
Product Support

Thanks again. I will post how the plane does on the next flight.
Keven
Old 06-23-2002, 10:42 PM
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thejetman
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Default I flew the Decathalon again.

By making the CG about 1 inch further forward than the plans called for. The plane took of nice, I turned and started to gain alttitude, the engine died and I turned the nose into the wind and the plane winged over and started to spiral down I could not pull it out and it went in hard nose first. The plane is not worth fixing(for the fourth time). At least the Decathalon did not kick my butt. I did manage to fly it for a few seconds till the engine stopped.
I really do not think that I will ever build or fly another Decathalon. There are too many planes out there that fly great and are easier to build.
Thanks again for all your ideas on the plane.
Keven
Old 06-24-2002, 04:56 AM
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bgi
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I want to thank all of you who have contributed to this thread for preventing me from experiencing the heartache and behumblement (that's a new word) that Keven has experienced. I was considering building a decathalon model, perhaps a GP. Now I'll be shopping elsewhere!

Geez, what a crappy plane this thing must be with all the negative SPECIFIC comments!

Maybe the Dynaflight kit is better (so I've heard).
Old 06-24-2002, 04:22 PM
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Default Great Planes Super Decathlon 40 Kit HELP!!!

You can't blame the plane for a deadstick........ I have the GP Decathalon, and it is a nice plane if you know how to fly it.
Old 06-24-2002, 05:14 PM
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I got one of these ready for it's first test flight. It was actually ready last year but because of the horror stories I never tried to fly it. Should I move the CG 1" forward and try to fly it or let it sit pretty in one piece? Any other recommendations to do before the first flight? FYI, I have a Saito 65 in the nose.

Thanks,
Brian
Old 06-24-2002, 07:23 PM
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MinnFlyer
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I would not say to go a full inch, just make sure that it balances at the front of the recommended range
Old 06-26-2002, 07:25 PM
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mscic-RCU
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I had (keyword here is had) a GP super D also. Terrible plane. You are probably taking it off too soon, let it run out on its own until it wants to takeoff on its own. When it rotates you will probably need only right rudder until it gets some airspeed. Do not stall it in flight, they have a tendency to enter into a non-recoverable flat spin. My advice is to sell it to someone you dislike before it reaches its expiration date!
Old 06-26-2002, 09:42 PM
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I love it.....halfway done with building mine and I read all the horror stories. That's ok I am bored with all my excellent flying models and need a challenge. Plan on putting an OS 70 on mine. Is that enough power to pull off the "Snap spin Recovery from Takoff" maneuver? After that I will develop my "Un-intentional Harrier Landing" ability.
Old 07-01-2002, 06:07 PM
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Default Great Planes Super Decathlon 40 Kit HELP!!!

My mentor has one, I bought him the kit to thank him for teaching me to fly, and it is almost impossible to taxi it straight for a take off. The first time he flew it with a Saito 72 it took off and snapped into the ground. He's tried everything to make this plane stable on taxi, once in the air it flies great. He bought a gyro to install on the rudder so we'll see if this works. He's a excellent flyer and builder so those to considerations aren't the problem.
Old 07-01-2002, 06:17 PM
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mscic-RCU
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I have a friend with a super d and a four stroke, i can't remember the size off hand. you have to let it run out to get up to airspeed and lay in the right rudder. a prayer doesn't hurt either!
Old 07-05-2002, 02:51 AM
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Jayebird
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Default For sale?

Are there any salvagable parts? I have a scratch built 40 size Decath. I might need parts for.
Old 07-16-2002, 02:47 AM
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Default Washout

I am in the process of starting my Great Planes Super Decathlon kit and have read mixed reviews on the tip stall tendencies of this plane. Half of me says build it with washout in the wings, the other half of me says to build the wing straight and learn to fly this plane properly. To the guys who fly this plane and have had no problems, do you think washout is necessary?


Thanks.....
Old 09-03-2002, 05:01 AM
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A4HawkPilot
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Default Great Planes Super Decathlon 40 Kit HELP!!!

I built one years ago. All of it was built to the plans given. I had a YS .45 on it and it flew just fine. I thought it was a great little airplane! Every airplane flies different. Just because it doesn't fly like your trainer doesn't mean its a bad design.
Old 09-03-2002, 06:50 AM
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nick.wright
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Default no prob with the GP Super D

Had a GP Super D once with NO PROBLEM WHAT SO EVER. Bought it already built from a guy at a fly-in. Put a Megatech .46 in it and flew the wheel pants off of it. Would do partial power take-offs with no problem. Yes, I said partial power--1/4 throttle. Would fly like a trainer at half throttle then open it up for full aerobatics. Could also bring it in at a crawl to land. Lost the plane while doing a low-level inverted pass. Pulled back on the stick instead of pushing forward. Completely destroyed all of it. Liked it so much, I bought 2 kits which will be flying shortly. I did however, built the washout into both wings. I think this is what really makes the difference with this plane.
Old 09-03-2002, 07:25 PM
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caf2461
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Default Washout

Mine is framed up except for the wings. Several folks mention there is a recommendation by Great Planes to build it with washout to reduce the tip stalling tendency.....

Anybody know what this recomendation is? Mine is an old kit with no mention of washout.

BTW Ive decided to use a Saito 65 I had on hand and chase mine around the runway. Should be a welcome change from my go where you point them pattern planes - sounds like fun.
Old 09-03-2002, 07:35 PM
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Derrick-RCU
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Default Great Planes Super Decathlon 40 Kit HELP!!!

Check out this page on great planes website:
Tech notice

I decided to build mine without washout........I went with an OS46fx instead of a 4 stroke and also did some thinking about washout before building the wing. The wing is fully symetrical and I am not an expert by any means but it did not make a whole lot of sense to add washout to a symetrical wing, especially since I love doing low inverted passes with any plane that I own!

I think the key to this plane is to remember it is not a trainer and to get the speed up before yanking it off the runway....also watching the speed on landing.

Mine is framed up and the wing has been covered, hope to get some flights in on it before the end of Sept...(02)

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