i have 271/2 in aileron's on ea wing would like to add flaps,(the plane is a tiger 60 with 70 wings) how much flap would i have to use (or cut from the aileron ) to make the flaps work and what would that due to the use of the aileron's

A very general rule is that the each flap would be 1/3 the length of it's wing half and the rest aileron.
You would have to increase the throw of the aileron to get the the same performance as before.

On that non-scale aircraft, I would personally suggest not using flaps, but installing a separate servo on each existing aileron and plugging them into different channels. Then, use your computer radio to set up flaperons. A whole lot easier and works just as well.

Highflight

i agree
go with two servos and set them up as flaperons
that way, you can fly non flap or add flap as you want
the aileron size would not change

That is the easiest way to do it, but if you want them, they are fun. Do it as Highflight stated and increase the chord of the flap. Watch for the nose to pitch up as you drop the first 20 degrees of flap.

Actually you could install flaps and with four servos and a computer radio you could do a lot more. Flaps with seperate ail. Combine flaps and ail. for full ail. or full flaps and you would also have crow capability.

I've done flaperons on two models in the past and THEY DO NOT WORK. At deflections much past 30 degrees (just where the flap action gets interesting and valuable) the ailerons become unusable due to adverse yaw. But if you cut the existing strip ailerons then you don't have enough chord for either the flaps or ailerons to be truly effective either.

I'm afraid the only way to make it work in this case is make wider strips and cut them at the proper points to make separate surfaces. Ideally you will do this during construction so you can move the trailing edge of the wing rib structure to compensate and retain the same wing chord. But if this is a retro-fit then make new surfaces with about twice the chord of the old strip ailerons. And if it was me I'd make the outer 60 % of each wing ailerons and the inner 40 of each wing flaps and couple the two flaps to one servo.

A while back I did flaperons on a 40 size plane. Interesting project. Fun to play with but came to the realization that it was wasted effort on a plane this light that already had good landing and take off characteristics. Still I enjoyed it as it did work very well. As far as splitting ailerons for individual flaps when removeing 30% of the ailerons length it seems that adding that same lost 30% to the chord length would make sense as well as increasing the chord length on the flap to match. Joe