LukeWarm Show full post »
ASD
ok Luke I read this whole thread and it still says nothing about how much room there nneds to be at the tip of the prop, I got the slot part down, no problem there but can i put a 8in prop in a 8 and 1/16 hole or will this cause a problem?
Cuz tooling around is just not my style of flying. Full stick and full travel control surfaces.

http://www.youtube.com/user/DollarTreeFlyer/videos
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LukeWarm
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ok Luke I read this whole thread and it still says nothing about how much room there nneds to be at the tip of the prop, I got the slot part down, no problem there but can i put a 8in prop in a 8 and 1/16 hole or will this cause a problem?
It says to listen to the noise. If the foam interferes with the prop's shock wave or the free flow of the prop wash, you will hear some extra noise. The clearance distance needed on the ends depends on the prop and the RPMs it will run. Noise is lost energy. I like at least a 1/4 inch on each side, but sometimes you can get away with less.

POST NUMBER 1 and 29: "The main goal is to improve thrust by making the foam behind the prop more friendly to the swirling motion of the prop wash. This should not only increase the thrust by about 10%, it will make the jet quieter. The prop wash hitting the foam behind the prop makes a lot of noise as it creates vortexes that block air flow and kills performance".

POST NUMBER 30: "The shock wave in the area very close to the prop will prevent us from putting anything too close to the prop. This shock wave is the only thing we must allow for in front of and on the ends of the prop".
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Flightman
What about bending the foam to 'straighten' the air?
Don't tread on me!

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LukeWarm
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What about bending the foam to 'straighten' the air?

When you try to streighten something out, your aserting force on it. Deflecting thrust by straighten it, takes energy from the thrust. I think the smartest thing to do is to not interfere with the prop wash, conform the foam to it. The farther the prop wash's airflow gets from the prop, the more the airflow straightens out.
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ggunners
There's a good Otto Dieffenbach video with some prop slot testing here. -- ggunners
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