aeroboy1293

Hi all, what props are you all running on the ft-300's, I have one that I bought second hand fitted in a GP Christen eagle. At the moment it has a G-sonic graupner 22 x 8 which it spins at 7000. What would you recommend.

Bax

My Feedback: (11)

That sounds about right. We'll also use an 18 x 10 Top Flite wooden prop. Run the engine in the mid-to-high 6,000's, and you'll be OK.

aeroboy1293

Cheers Bax, Running with that prop and 5% nitro 18% oil fuel she is getting quite hot inside that Christen eagles cowling. Performance is not affected by this heat, but she does seem to be a tad hotter than what I'd consider as normal. There is more than enough cooling and exit area heat escape. Would a switch to say 10% nitro and 20% oil help cool her down.
I'm richening up by around 200 rpm from peak to 6800, is that about right or do I need some more. I believe the engine has only been flown 8 to 10 times from new.
Would a Graupner G-sonic 20 x 8 spinning at 7800 on the ground be a little under propped then.
Cheers

James

Bax

My Feedback: (11)

If the engine appears to be running hot inside a cowling, you may want to add baffles to make sure that any cooling air that enters actually flows through the fins of the cylinder and head. Many times, the air will just bypass the engine and go directly from air inlet to the air outlet without passing across the engine. If you can look into the air inlet and see the air outlet, then that's the path the air will be taking.

aeroboy1293

Bax, I'd made up some very simple baffles last week and hopefully try them out sunday. I've also changed fuels and props so time will tell if it cools things down. I've also been doing some forum research and found that these twin cylinder engines need a fair bit of running in before they are at peak performance. I'll try flying it on the 20 x 8 and 22 x 8 with the new 10% nitro 20% oil mix and see what happens.