A7Bldr

My Feedback: (40)

Regarding engine thrust: Does a smaller turbine (say a Merlin 90) that generates 20 lbs of thrust, fly an aircraft differently than, say a JetCat P-80 at 20 lbs. ? The tailpipe using the Merlin engine will be a smaller diameter, and have a higher speed exhaust .....

Does this mean that the P-80, having a larger dia. exhaust, will have better vertical than the Merlin ? Perhaps a shorter takeoff?

I understand that different aircraft fly differently, but lets assume a very generic, sport flying airplane with a trainer-type wing and the same weight.
Thanks,
Jim

samo

Ya know I heard that too. For instance, a P-60 powered Bandit ARF was indeed faster than a P-70 powered ARF, because of the exhaust gas velocity on the 60. Sure vertical was better on the 70 and takeoff distance but once the 60 was up and running, its faster than the P-70 in the Bandit ARF.
I think the Merlin 90 would be faster and have the same vertical, takeoff performance as the P-80 but thats just what I think I don't really know.

Andrew

KC36330

in the vertical, thrust is thrust and equal poundage gives the same performance, but yes faster exhaust velocity gives faster speed with all other things being equal.

sidgates

My Feedback: (2)

Jim,
I have flown my Boomerang Intro with both the RAM500 and my WREN SS. I have read the WREN has a lot higher exhaust velocity than the RAM500 but I find I fly the Boomerang at about the same cruise speed but with slightly lower throttle setting on the WREN. With the WREN SS I notice a lot shorter take off runs and a lot more verticle at full throttle.

I am not sure this helps you.

A7Bldr

My Feedback: (40)

Yeah, I'm considering an engine for one of our A-7's. 20 lb of thrust (or more) would be nice. I have a short field to work with and don't really care about high speeds.
I've considered a P-80, P-120, Merlin 90, Wren -120..... I do like the Merlin for its size and weight.
Jim