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

patriot XL,rear ex.

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Old 11-22-2004, 11:08 AM
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RVBlack
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Default patriot XL,rear ex.

does anybody out there have a patriot XL with a Jett 90 rear exhaust , pipe on side of fuse? Will the extra power from that big marine pipe not be worth the extra drag? Will the pipe disrupt the air flow to the elevator and make the plane fly funky? Whats your set up? Whats good? Whats bad? What would you do differnt? I need info. maybe some pictures.
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Old 11-22-2004, 11:46 AM
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Default RE: patriot XL,rear ex.

I'm not all that sure you will see much more performance with a FIRE 90L as oppose to a standard side exhaust 90L.

The XL is a big bird..... quite a bit of drag even with the gear up and stuff. It will take more than the extra 400-800 rpm you will see with the full pipe (same prop) to return a measurable speed increase.

Power and design wise, the FIRE and side exhaust 90L are about the same. You can get more power/rpm from the rear exhaust, but this is mainly due to using the big pipe and having it tuned for a more specific rpm target (higher RPM, smaller prop perhaps).

I do know of one customer who has a FIRE90L intended for an XL, but he is using the quite pipe.... mainly intended to meet some field noise requirements. Setting the pipe a bit long, turning higher pitch..... a bit lower rpm (Shooting for 12,500 if I recall... its been a month or so)

You should not have any issues with turbulence or anything from a pipe running down the side. I use to set up pattern ships like that on occation. Drag is not really an issue with the pipe. A bit better than an even trade for the side exhaust muffler. Your decision to run the RE version is just a matter of a trade-off of some more complexity (and cost) for a marginal return.

I will defer any further specifics to anyone who has built a RE version of the patriot.

Bob
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