Great Planes PT-40 wing modification

HI. I'm a newbie to flying and this is my first kit. I've been
talking to some local flyers about my kit (waiting on FedEx to get
here) and have read some OLD posts here about the dihedral.
The locals are suggesting that I build the wing with no more than 2
inches of dihedral, and that seems like a simple modification, but
they also suggest removing some of the washout. Since I am on a
limited budget and won't be able to put a sport plane in the air for a
while, I would like to get as much aerobatic capabilty out of the
plane as I can without losing all of the trainer qualities. My
question is; how much washout should I have and how do I go about
making the modification? It looks to me like it's going to require
modification of the wing ribs.
Reply to
dredhea
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Since the PT-40 is a kit, the mod is simple. Make a new spar joiner with the reduced angle. Glue the root ribs in at the new angle, rather than the angle called for by the kit. Do this by proping up the wing tip the required amount and glue the root rib in verticle to the workboard. That way the root ribs will be flush to each other when you join the wing panels.
Washout....... anyone else got comments on that??????
David
Reply to
David AMA40795 / KC5UH
I learned on a PT-40 and I wouldn't change a thing. It is perfectly designed for the task.
-- Paul McIntosh
Reply to
Paul McIntosh
Cut the dihedral in half, leave the washout in. Washout creates an anti-stall characteristic that you want. This means the plane will fly slower without stalling.
Concerning trainer modifications: I built an Eagle and an Eaglet, both with 1/2" dihedral, and conventional (taildragger) landing gear. Both planes were good trainers and good sport planes.
Good luck and keep us posted.
Dr.1 Driver "There's a Hun in the sun!"
Reply to
Dr1Driver
HI. I'm a newbie to flying and this is my first kit. I've been talking to some local flyers about my kit (waiting on FedEx to get here) and have read some OLD posts here about the dihedral. The locals are suggesting that I build the wing with no more than 2 inches of dihedral, and that seems like a simple modification, but they also suggest removing some of the washout. Since I am on a limited budget and won't be able to put a sport plane in the air for a while, I would like to get as much aerobatic capabilty out of the plane as I can without losing all of the trainer qualities. My question is; how much washout should I have and how do I go about making the modification? It looks to me like it's going to require modification of the wing ribs. ================================ I built the big brother to this plane (PT-60) last year. It called for 4" total dihedral with the 'sport' wing and 6" with the 'trainer' wing. I built the 'sport' wing and everything lined up great with 3" dihedral so I stopped sanding and glued it up. I talked to my instructor about the washout and he said to just build it flat and it will be fine. Even with the jigs that come in the kit, he said it would be easier to build two flat wings than two evenly twisted wings. I built them flat and the plane flies great.
No matter how you decide to build it, there is no modification to the ribs. To build in the washout, you twist the wing and glue on the sheeting to hold the twist.
I do not consider myself an expert builder, and I'm still flying on a buddy box. Just relating my experience with a very similar kit.
Carrell
Reply to
Carrell
"Cut the dihedral in half, leave the washout in. Washout creates an anti-stall characteristic that you want. This means the plane will fly slower without stalling." I agree 100%. I built and trained on the big brother PT-60. The Great Planes PT trainers are excellent trainers. Keep the washout and a little dihedral. You'll like it and have a great flying and stable trainer. Howard
Reply to
Howard
I built one back in '91...and still fly it on occasion.
I also have TWO different wings.
I purchased an extra wing kit from Tower and I was glad I did. For the beginner, the standard wing is designed with a lot of dihedral and a fair amount of washout--and is for 3 channels. With this wing, half throttle is max (OS FP-40) for cruising or it'll climb out of site.
The other wing has ailerons, less dihedral and no washout--and is for 4 channels. It makes for a much improved plane with no problems at all. It's not aerobatic by no means, but is really a joy to fly.
The PT series of planes is a great place to start!
Reply to
KayCee
Thanks, KayCee. I've thought about a second wing later on, and may build it totally flat and without washout(when my skills allow me to fly it that way). For now, I plan to go with standard washout, 2" of dihedral, aileron control (ailerons can be locked down on this model), Tower Hobbies .46 for power and Futaba 6EXA electronics. I'm going a little overboard on the radio and engine now as my limited budget may force me to "steal" the engine and get a second receiver and servos to move on to a my second plane. I don't think that I'll need 6 channels for a very long time, but I really like the model memory function that the EXA has.
Reply to
dredhea
I don't know why most everyone thinks a big high wing trainer with low wing loading is the "best" type of plane to learn on. Here in Kansas these high wing, box fuse's, with huge tail fins blow around like kites in the winds that are normal for this area....almost ALWAYS over 10-15mph. We usually have lots of gusts and cross winds to deal with. Don't wait for a "calm" day cause there ain't any.
IMO, the "best" trainer for windy parts of the country are the Sig 4Star line of low wing planes, perhaps set up with a trike gear, especially the Fults nose gear. Leave off the outer spar at each end of the wing when building to have a little MORE wing loading. Or do what I did, and just add some weight to the wing tips at the CG point, which gives you the extra wing loading and makes the plane more wind proof.
Trainers for windy areas of the country benefit from;
A little more wing loading, especially if distributed outboard of the fuse. The plane will cut through the wind better and landings will be more predictable. I've seen plenty of those light loaded trainers balloon on approach when a stiff gust came out of nowhere, only to become kits again. And all that dihedral, which is so nice for floating a plane in on that perfectly calm day, just adds to your problems when that Kansas crosswind gets under it and sends it post-haste into the wheat field next door.
Trike gears, with some rake in the nose gear; they track straighter in crosswinds.
low wing planes with rounded fuses don't blow around as easily as high wing box cars.
Plenty of rudder, but smaller fins overall.
A low pitch prop gives you more thrust right off idle (nice when trying to get out of trouble) and also slows the plane's top end speed down some (which is also usually good when training)
It's not how much the plane weighs overall (within reason), but WHERE the weight's LOCATED. Weight distributed to the front/back and end of wing tips is best.
If you can learn on a high wing trainer you can learn on a Sig 4Star. I found them actually easier to takeoff, fly, and land than the high wingers.
opinions will vary, jk
P.S. washout is a method of getting the wing to stall first inboard near the fuse. Planes that stall at the outer wing first usually end up in a nasty spin. Box type wings (ie. trainers) don't really benefit from washout much, but rounded tips (ie. Spitfire) really need washout.
Reply to
John N. Kessler
Most of us ain't in Kansas/Tornado Alley. :) You could fly a brick in some of the wind you guys have out there. :) Dr.1 Driver "There's a Hun in the sun!"
Reply to
Dr1Driver
It ain't the wind I'm worried about. Any of you guys want to fill me in on cold weather engine starting procedures. We get two seasons in upstate New York (near Lake Ontario), winter and July 27th. :)
Reply to
dredhea
Higher nitro, say around 20%. Parallel your glow lighter - 1.2v, 2000-3000mah typical. Keep the engine warm in the car until just before you start it.
Jeez, when it gets that cold down here in the South, we just go build. :)
Dr.1 Driver "There's a Hun in the sun!"
Reply to
Dr1Driver

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