flying poodle

My club has decided to try a Q-500 type competition. The only rule deviation is that the engine has to be an O.S. 40 LA. I have one of these engines and know all of the horror stories about them because they have happened (broken remote needle valve, broken carb, leaking back plate, and loooowww power). Even though I dislike this engine, I do believe it is a good choice to start a club level racing event, as they are very reliable, easy to adjust, and CHEAP.

My question concern the airframe. Most of the people who will be competing will be using ARF's or other prebuilt kits. I once had a Q-500 plane with a JETT 40, but I sold it. I have built about 8 different airplanes including big gassers, 3D fun fays, trainers, and 1/2 a planes out of insulation foam. These planes are cheap and fly well. I have built a Q-500 airframe out of this foam, but the airfoil is a flat bottom type and is 1.5 inch's thick. I realize that a symmetrical airfoil is the way to go for less drag, but the flat bottom is very easy to make!

Will I have problems with this airfoil in an airplane that will only be going 70-80 MPH? The completed airplane weighs about 4lb ready to fly, but I have not flown it.

daven

My Feedback: (1)

The airfoil is probably generating a lot of lift, which you are cancelling out with either incidence, balance, or elevator trim. The nice thing about a symmetrical airfoil, and an incidence very close to 0/0/0 (tail/engine/wing) is that you don't waste speed with one thing fighting another. You need very little lift in a Quickie primarily because they are overpowered.

I'm not sure I would have chosen the LA as you suggested, but for keeping things cheap INITIALLY, it is not a horrible choice. Try to get that wing down to the minimum of 1 3/16" thick on your next try. That 5/16" of extra wing thickness will really slow you down.

Alabama Racer

Come to Chattanooga this Saturday and watch a Quickee race. E-mail me for directions if you are interested. We will be flying standard quickees with mainly Thunder Tiger .40's.
Brad Clayton
[email protected]

flying poodle

have re-done the wing. It is now 1-1/4!QUOT! thick and simi-symectrical. I just recut the original wing and it was not possible to get it fully symmetrical with out a new core. The fuse is 36!QUOT! long with-out engine and the tail plane is coro reinforced with bamboo skewers (a.k.a. spad). The completed plane with engine and radio weighs rite at 3.5 pounds and is a low wing design.

I am not looking to design the greatest pylon racer, but will I be competitive with the ARFs? Will the flight speeds that we will see show the need for a more refined airframe? Or will the L.A. power keep everyone fairly equal?

daven

My Feedback: (1)

I think your best off with the ARFS (Viper, and Preditor). I seriously doubt a quickee with a coroplast tail will be competitive speed wise, but who knows.

The LA should keep speeds relatively equal, if the airframes are equal.