I was reading about the Predator and would like to get one and run my OS .32 Heli engine with a tuned pipe on it. They do state with some pylon racers to use carbon fibre in the wings for additional strength. I think the specs on the Predator call for a .25-.28 size engine. Am I likely to blow the wings off with this .32 or do I need to add the carbon fibre? It really screams.

It is the speed of the airplane that is used to determine if the wing needs strengthening not a "screaming engine". If you are that concerned about the welfare of your engine, airplane and radio equipment then do the modification anyway or, buy a racer that is meant for the job.

To apply a slightly more scientific approach, figure out the expected speed of the model. for this you will need to know the pitch of the prop and the approximate flying rpm of the engine.

Pitch x RPM x .000947 will give you a THEORITICAL mph. This is of course ignoring all prop slippage etc. etc. Anything over 120mph and I would suggest the whole airplane is looked at, not just the wing.

If you do a search you will find countless threads about strengthening this airplane. To me it seems pointless to buy an ARF and then do all of the work that is suggested to make it flyable. Why not build a racer properly in the first place?

Ed S

Thanks, Ed.

George the Preds are used by many in five western states for three pole AMA 424 APRA racing typically they will reach 125 mph using almost universally TT .40 Pro with muffler per rules and proped for around 16500 with a mandatory APC 9x6. I suspect even piped with your engine it will be somewhat slower. The lack of CF under the skins is not an issue and not needed in 424. Its with Nelson and Jetts in 428 where they do go around thirty miles faster that it does become an issue.

Check around and find out what racing may be near and why not build to local rules to give racing a go, but I must warn you it is infectious.

John

Ed makes good points, but with a .32 you will be fine with the stock wing.

We race them locally with the O.S. .46fx, and the wings are fine up to 130 mph. I've only seen problems with them with Nelsons or Jetts around 160 mph.