Some questions

[treyal]

We are bulidng a P40 (400 series).

The rubber doesn't seem to give it enough power for the plane to take off.
What is an alternative to use? Performance oil?
The kit shows a three prop propeller but the kit comes with two prop.

Are there any other non toxic dope like products?
We use 50/50 glue to apply the tissue paper and maybe arylic paint to finish. Will a clear coat work to seal it up?

Where is the balance point (center of mass) on the model?

Thanks for your help.

[Bean]

Are there any other non toxic dope like products?

Non-toxic...I'm not sure...but there are alternatives. Butyrate dope, nitrate dope, WB poly, and even Future Floor finish! I'm actually contemplating starting a thread dedicated to tissue finishing...

We use 50/50 glue to apply the tissue paper and maybe arylic paint to finish. Will a clear coat work to seal it up?

Yes. My method is usually as follows:
2 coats 50/50 clear dope/thinner to seal.
Fly the plane....then paint (I like to make sure it's flight worthy before committing to paint.).

Where is the balance point (center of mass) on the model?

The CG should be marked on the plans...if you don't have them, then a rough estimate is 1/3 wing chord back from the LE....perhaps where the main wing spar is. Or you could get fancy and use a calculator.