Flaps for thermalling?

[davidleitch]

Hi

I'm flying an electrified 2.5 metre Organic (57 oz AUW). This plane has an MH32 airfoil and seems to cut through the air a bit quicker than what I'm used to.

I've read a lot about putting the flaps down a few degrees for thermalling, but I'm wondering whether this is worthwhile? Wouldn't it be bettter to just trim in a bit more up elevator?

regards
dave

[vario]

trimmer the pitch slows the glider and handling etc,adding flaps under cambers the wing for a slower stall speed

while thermalling it will give you a more forgiving wing with better handling although your trim speed will have to be adjusted as well with the flaps added


,,,,,,,vario


ps i some how get the feeling this question will not be answered to easy,

it has a lot to do with personal preferances

[Jack Hyde]

I fly a Mantis with a MH 32 wing. At high cl conditions (low speed) 5 deg flaps produces the same cl at a lower cd than no flaps. Therefore you can fly slowly with less drag (slower sink) when you drop the flaps 5 deg. I use 5 deg flaps on both MH 32 and SD 7037 when in a thermal.

[dephela]

Increasing camber will help when thermalling.

The MH-32, like any airfoil being "cambered", should have the entire trailing edge treated. Both the ailerons and flaps should be lowered so that the TE is a single line.

It won't help that much when you are looking for lift but will make it easier to stay in the lift. The plane will fly slower and stall at a lower speed making those initial turns easier. When you've established yourself in the air, you may find that the optimum foil is once again a normally cambered foil. That speed will help to keep you out of trouble in the more open turns made up higher.

.09-.12" on a 2" flap[for the MH-32] is about what works best. You may be finding that the MH is faster tha what you have been using. I'm sure you can get used to it, especially knowing that it can be slowed in normal flight as well by[as you guessed] trimming. If you have been flying planes with a more forward CG, bringing it back will help in this respect!

[Ollie]

When you are between thermals, use no flap or even a little reflex because you want to get out of the sink as quickly as you can by flying fast. When you first enter the thermal and begin mapping out its size, a medium flying speed with plenty of stall margin is helpful, especially if the thermal is turbulent and you find yourself fighting your way in. Once you are cored, then trailing edge camber becomes quite useful if the circles are small because you don't have to bank as steeply when you can fly slower. The slower you fly and the less you have to bank, the quicker you will climb in a thermal.

If you are uncomfortable flying fast, the solution may be a plane with a higher lift airfoil and a lighter wing loading. The lighter the wing loading and the thinner the airfoil the more versitile the plane.

[Tim Jonas]

I reflex the flaps on my Xenath a few degress in thermalling. It helps, I believe.