Hi,

I've got a Webra .91 P-5 engine and thinking about putting it in a Venus II.

The engine is a typical European engine being designed to run on zero or low nitro fuel, is more for torque rather than all out revs.

I guess it falls somewhere between an OS .91FX and 1.20AX in power delivery. It can swing a 14x12 at around 8,500rpm and a 15x8 around 9,500.

Do you think the Webra will be enough to compete in Sportsman class with the Venus II.

My engine/muffler weighs in at 825gm (29oz) which is about 2oz less than the OS 1.20AX with stock muffler and extension. I can get a muffler which is 2oz lighter if needed, but that would require some cowl cutting to fit.

I'll be mounting the servos in the rear and using Futaba 9255's on Ailerons and Elev. Rudder will be a 9151. Receiver will be powered by 2100mAh LiPo and regulator set to 5.2V.

I was swinging an APC 15x8 at 9500 RPM (10% nitro) while my engine was breaking in, and it was puh-lenty for Sportsmans. I think it's safe to say that power was the LEAST of my concerns! I have the 120AX and had to add something like 2 1/4 oz to the tail (although I do have a forward mounted throttle servo), so the weight savings up front will be good. I have room to move the engine aft and I might do that later this year or next winter, but the point is your plane should be 1/4lb lighter than mine. I tried a 15x10 to start and it was really nice, but my new engine took too long to reach RPM with it and acceleration was a bit slow. Of course try some different props to see what you like best but I think you will be fine with that .91.

Tower sells the Venus II combo with a TH .61[8D]

A .91FX flies the Venus II in Sportsman, so if your assessment that the Webra is between the .91FX and the 1.20AX, you should be good to go. Keep the weight as low as possible. If you get towards 9.5 lbs, it will need the 1.2AX to do the rolling verticals in Intermediate.

I flow the Venus II with OS 91 FX with 14x8 APC prop. It was just enough power to do the maneuvers in the norwegian sport 07 programme but i feel it would have been better with a bigger og more powerfull engine. I run on 15% nitro.

I had both Webra 40 and 50 and they are great engine running exelent on 5% nitro.