i tried building a thermocol model, but cannot get my plane in the air............. i was doubtful abt the construction and so i stripped the plane of the motor and battery and looked whether it flied when i pulled it with a string......... it barely takes off, and it comes crashing down with a nosedive........ can u help me solve this problem?

1. You should post pictures of your plane. That would be a starting point for any troubleshooting.

2. Proper way to do glide tests is to throw it from shoulder height with wings level into tall grass, and  WITH with motor etc, so that it is in the same condition as it would be in real flying.  Pulling with a string sounds strange.  Here is a video of someone doing glide tests :

http://www.rcindia.org/self-designed-diy-and-college-projects/glidiator-my-first-trainer-build-log/msg30830/#msg30830

But it is best done into tall grass, as it may have tendencies that can cause it to not reach the person ready to catch it.

Pictures attached.

hi. i live in kerela and need some urgent help with building my plane...i made a plane using thermocol and masking tape, used a small motor and propeller that i got from a broken readymade rc plane.............. my plane can only stay off the ground for a few seconds....... it sortof glides through the air when the motor is running........ it cannot gain altitude and it does not gather enough speed on wheels to take off........ i still havent figured out what is wrong..... do i need a new propeller, or do i need a motor? i tried to get new ones, but cant find a hobby shop anywhere in alwaye...... theres one in palarivattom shown on google maps but i cant find it..........    i'll post pics of my plane later.......... cant get my cam to work right now....

i just wanted to know, whether we can introduce slats to thermocol airplanes because i just read in wikipedia that slats can increase the lift to up to 60%-   the plane i just made does not go up because the wing does not produce enough lift{i think} for the plane to fly at the small speed produced by my recycled motor and propeller..... also, can anyone tell me how to reduce drag on the aircraft? i dont really know what drag is, but im guessing that it is some force that prevents the plane from flying and i just read that introducing slats can increase drag too........

Merged... please do not create many threads on the same issue.

Did you make a completely new plane, or did you just tweak the one above ?

PS: Either way, it seems good to continue discussion in this existing thread, which is aptly named

Back to the discussion of why it does not fly, the basics are this :

http://www.rcindia.org/rc-general-topics/how-much-of-a-thrust-is-sufficient-to-takeoff-a-plane-and-fly-it-normally/msg62992/#msg62992

So the first question is what is the AUW of your plane, and what power system are you using ?

The most important thing is that rockets do fly, and they have zero airfoil.  Given enough thrust, anything can fly, even a plain sheet of thermocol !

Like Anwar said, do not stress yourself over selection of airfoil and other complicated stuff right now. Your wings look good, but picture of your fuse is not clear. Can you post a complete picture of your plane. Also what is chord and span of your wing, what motor-prop combination you are using  and most importantly what is the AUW of your plane.
If you are considering building a new plane, then read this thread about a simple plane build by medicineman, its a very good and fool proof design

can u direct me on the best wing designs to get highest lift in low speed conditions? the motor and prop im using does not give me much thrust, so i'll have to compromise about the wing shape........ if u can find good designs for low speed thermocol aircraft, please post them here.......                                                                                             thanks..