I'm assembling a GP Shoestring Racer and plan on using the ailerons as flaps when landing. Are the flaps supposed to go up or down? I guess I should know this but I have been told that they should go up by some people and down by others.

Flaps extend down from the wing. If the raise up then they are spoilers.

Ken

Generally, the flaps are dropped down somewhat for landing. Theoretically, this gives more drag and more lift and allows the plane to be landed at a slower speed. In practice, I have found this to be less than ideal however. Start with only a little bit of throw and try it at a high altitude for your first time. If you set it up with full throws and both ailerons drop down at full travel, the model may not be controllable. Generally, RC planes pitch down when the ailerons are dropped. Full sized planes have "real" flaps separate from the ailerons. These are always inboard of the ailerons and when deflected, the ailerons are still effective. Flaperons (as we call them) do not work as well, but they are fun to play around with.

Up and you call them spoilers.
Down and you call tem flaps.

Ok flaps go down and spoilers go up, I got that. Which do I want to use during landing? Does it make any difference?

Experiment with the flaps while you are a few mistakes high. Lowering the flaps will change the elevator trim, also it may change the stall characteristics. My Burrito develops a tendency to tip stall when flapperons are down.

As mentioned above, properly designed flaps lower the stall speed and, for larger flap deflections, increase drag. It is common in full-scale trainers to take off with around 10 degrees flaps (so they can take off at a lower speed) and to land with 10 to 30 degrees flaps. The Cessna 150 has 40 degrees of flaps and when extended to 40 degress a pilot can put the nose down to a steep angle without picking up speed. This is useful for landing over obstacles onto a short field. But this gives so much drag that pilots can get themselves in trouble when forced to abort a landing approach.... with full power they are barely able to climb out.

G'day Mate,
I have flown a Shoestring, maiden flight for a member of our club, & you won't need flaps, this plane flies beatifully, & will land surprisingly slowly, they are stable & rock solid in the air.
Enjoy.

Loochman,
Do not use spoilers close to the ground unless you are realy experienced. Spoilers cause the aircraft to drop like a rock. Use flaps. However, I don't think you will need them with this aircraft. I have seen this aileron used for flap thing with a Hangar9 P-51 Marie Mustang and the results were not very good. I told the owner I would make actual working flaps in the wing of his P-51 if he wanted. Good luck.

Flaps cause lift and drag in varying amounts when used.
Spoilers cause drag and loss of lift.

Which would YOU want on landing?
http://www.lerc.nasa.gov/WWW/K-12/airplane/spoil.html
http://www.centennialofflight.gov/es...aces/DI104.htm
http://www.centennialofflight.gov/es...ices/Tech6.htm
http://avstop.com/AC/FlightTraingHandbook/Wing.html

Some good reading.

Flak, tip mounted ailerons like the h9 p51 give wash in when dropped and cause tip stalling.

The h9 doesnt need flaps in any case, it lands like a trainer unless he's after the cool factor.

Hi!
Why use flaps on a Shoestring when the original racer did not used it...??
I have flown the Great planes Shoestring and it definitely doesn't need flaps to land ...you only need practice landing it!

Regards!
Jan K
Sweden

Thanks Everyone,

I think I'll put the flaperon option in the plane but I'll try flying without them as suggested. I guess they're probably not needed.
Thanks Bruce88123 for the links, they were very informative.

You really don't want flaperons on a Shoestring.

Normally flaps are inboard on the wing. Ailerons are outboard on the wing.

When flaps are lowered, because they are inboard, they create sort of washout on that wing. Washout helps avoid tip stalling. That's a good thing to help avoid on landing. Since the ailerons are outboard, if they were to deflect downward, they would actually create washin on that wing. Washin often causes tip stalling.

Do yourself a favor and do not setup that Shoestring's ailerons to act as flaperons. You really don't want to do it.

If the Shoestring was supposed to have flaps they would have been designed into the airplane. Neither the full scale nor the 1/4? scale airplane have flaps. That should tell you something. The airplane lands just fine without flaps and I can't think of a single reason to add flapperon mixing(that is what you will be doing) to the original plans. The plane lands a little hot and takes some skill in landing, but it isn't unmanageable and is a very popular airplane. Keep the speed up on landing and literally fly it onto the deck and you'll be fine. It isn't a beginner's airplane, more like a third airplane. Also, I think it is out of production.

Regards,
doubledee

Great Planes has a 1/4 scale ARF available still.