Return-Path: Received: from relay02.roc.ny.frontiernet.net ([66.133.131.35] verified) by logan.com (CommuniGate Pro SMTP 4.1.4) with ESMTP id 2603296 for flyrotary@lancaironline.net; Thu, 25 Sep 2003 10:10:59 -0400 Received: (qmail 18229 invoked from network); 25 Sep 2003 14:10:58 -0000 Received: from unknown (HELO frontiernet.net) ([65.73.142.179]) (envelope-sender ) by relay02.roc.ny.frontiernet.net (FrontierMTA 2.3.6) with SMTP for ; 25 Sep 2003 14:10:58 -0000 Message-ID: <3F72E9EE.B631AB39@frontiernet.net> Date: Thu, 25 Sep 2003 09:13:18 -0400 From: Jim Sower X-Mailer: Mozilla 4.77 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: DIE the short Answer References: Content-Type: multipart/alternative; boundary="------------55F3C663B5A21622AE2591D5" --------------55F3C663B5A21622AE2591D5 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit > <... Hey, hey, Jim. Watch who's work you are calling an > "remarkably extended brain fart.."{:>) ...> > The brain fart I was referring to was my tongue-in-cheek > notion of variable length runners would fix our life and make > 200 kts effortless. It suddenly (with my assistance too) took > on a life of it's own. Sort of a "brain fart blossom". > > <... vibration of large amplitude produced by a relatively > small vibration near the same ...> > I was using the term loosly. EDDIE does have some attributes > of resonance, notably resonant frequency. > > <... there is another factor (in addition to RPM) that is > much more dominate (don't ask - won't reveal ...> > I wont ask. At this juncture, I don't see it as a show > stopper. My guess is that most of the things that influence > it also influence Temperature. > <... a 50F drop in temp would equate to roughly 2.5" > (port-port) decrease in length ...> > That's a pretty good bit. There's a lot bigger variation than > that from low altitude summer ops and high altitude winter > ops, so 3" variation in telescoping intakes is, shall we say, > "problematic" - how do we simply and reliably move the entire > upstream end of the induction system 3 - 3.5 inches? But > that's a dead horse [fart] isn't it :o) > > Varying boost and perhaps intercooler efficiency might go a > long way toward stabilizing intake temps (and might > qualitatively influence your secret ingredient). Absent that, > how much decrease in RPM does a 50F drop in intake temp > require? A CS prop would achieve that at WOT and would go a > long way toward compensating for temp variations due to boost. > > <... review it at SERFI next weekend ...> What and where is > SERFI next weekend ? > <... so if you never hear from me again after that ...> > > I don't think Tracy (or anyone else) will find anything that > could even remotely qualify as a "show stopper". > > <... thought that the reason speed changed with temp was > because the density changed with temp ...> > May I suggest that you were in pretty good company in that > regard? Anyway, that's a dead issue. > > Anyway, the things that we know impact EDDIE are Intake Temp, > Runner Length, RPM and your secret ingredient (let's call it > "Pixie Dust" at least until it's better defined at Shady > Bend. Runner Length seems, at this juncture, to be the > toughest one to adjust real time (even though one might > construct "summer" and "winter" intakes (sort of like sneakers > and boots :o) and swap them at Sun-Fun and Shady Bend times > :o) If the rpm and air temp variations are manageable, we > might come up with an engine performance computer that knows > Runner Length and outputs EDDIE Intake Temp for current rpm > and EDDIE rpm for current Intake Temp. A display like that > could keep us adjusting rpm and boost and intercooler doors to > where we'd be assured that we're flying at the best possible > speed when we run into the Moony or mountain we didn't see > with our head up our "engine monitor". > > Where else could we have this much fun ... ONLY in America !! > .... Jim S. > --------------55F3C663B5A21622AE2591D5 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit
<... Hey, hey, Jim. Watch who's work you are calling an "remarkably extended brain fart.."{:>) ....>
The brain fart I was referring to was my tongue-in-cheek notion of variable length runners would fix our life and make 200 kts effortless.  It suddenly (with my assistance too) took on a life of it's own.  Sort of a "brain fart blossom".

<... vibration of large amplitude produced by a relatively small vibration near the same  ...>
I was using the term loosly.  EDDIE does have some attributes of resonance, notably resonant frequency.

<...  there is another factor (in addition to RPM)  that is much more dominate (don't ask - won't reveal ...>
I wont ask.  At this juncture, I don't see it as a show stopper.  My guess is that most of the things that influence it also influence Temperature.
 <... a 50F drop in temp would equate to roughly 2.5" (port-port) decrease in length ...>
That's a pretty good bit.  There's a lot bigger variation than that from low altitude summer ops and high altitude winter ops, so 3" variation in telescoping intakes is, shall we say, "problematic" - how do we simply and reliably move the entire upstream end of the induction system 3 - 3.5 inches?  But that's a dead horse [fart] isn't it :o)

Varying boost and perhaps intercooler efficiency might go a long way toward stabilizing intake temps (and might qualitatively influence your secret ingredient).  Absent that, how much decrease in RPM does a 50F drop in intake temp require?  A CS prop would achieve that at WOT and would go a long way toward compensating for temp variations due to boost.
 <... review it at SERFI next weekend ...> What and where is SERFI next weekend ? 
<... so if you never hear from me again after that  ...>

I don't think Tracy (or anyone else) will find anything that could even remotely qualify as a "show stopper".

<... thought that the reason speed changed with temp was because the density changed with temp ...>
May I suggest that you were in pretty good company in that regard?  Anyway, that's a dead issue.

Anyway, the things that we know impact EDDIE are Intake Temp, Runner Length, RPM and your secret ingredient (let's call it "Pixie Dust" at least until it's better defined at Shady Bend.  Runner Length seems, at this juncture, to be the toughest one to adjust real time (even though one might construct "summer" and "winter" intakes (sort of like sneakers and boots :o) and swap them at Sun-Fun and Shady Bend times :o)  If the rpm and air temp variations are manageable, we might come up with an engine performance computer that knows Runner Length and outputs EDDIE Intake Temp for current rpm and EDDIE rpm for current Intake Temp.  A display like that could keep us adjusting rpm and boost and intercooler doors to where we'd be assured that we're flying at the best possible speed when we run into the Moony or mountain we didn't see with our head up our "engine monitor".

Where else could we have this much fun ... ONLY in America !! ....  Jim S.
 

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