Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

K&B 7.5 mini pipe

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Old 03-01-2006, 12:54 PM
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airega1
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Default K&B 7.5 mini pipe

Where can I find a mini pipe for a K&B 7.5 or even a small tuned pipe (nitro pipe)
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Old 03-01-2006, 04:17 PM
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HighPlains
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Default RE: K&B 7.5 mini pipe

By "mini-pipe", I assume you mean the short open exhaust pipe like was used in the old Formula One engines on 65% nitro. For one of those, it can be made from 1" conduit pipe with a slight bit removed from one end on the inside to provide a lip for the O-ring seal. You should make several, as the length does matter slightly. We used to run 3.4 to 3.6" for the rpm range on the 6.5 engines (about 21.5 K on the ground, around 26-27K in the air).

One thing about the mini-pipes vs. the tuned pipes. There is no rpm limit in the air, so on a very clean airplane, the engine will rev until the drag matches up with the engine power. Whereas, the piped job will self limit at the tuned rpm, as the hp falls off rather quickly above that rpm. So diving an open pipe'd plane is quite different.
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Old 03-02-2006, 09:00 AM
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Default RE: K&B 7.5 mini pipe

Frank,

depends on what your application is, and the rpm you will be running.

Macs I believe still has the 7.5 "stinger" ducted fan mini-pipe. Very short and pretty loud. Will work ok if you are turning up rpm like that.

Weston/Eurotech makes a nice RE mini-muffler/pipe - no doubt they have one compatible with the 7.5

The Jett RE version of the jett-stream will work too. I believe the O-ring mounting is the same as the ST/K&B/Jett/Nelson F1/FAI type engines, and thus likely the 7.5 fan and sport RE engine, and the Jett FIRE series engines.
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