Return-Path: Received: from bree.pipcom.com ([204.92.62.3] verified) by logan.com (CommuniGate Pro SMTP 4.1.4) with SMTP id 2600420 for flyrotary@lancaironline.net; Tue, 23 Sep 2003 13:48:59 -0400 Received: (qmail 19478 invoked from network); 23 Sep 2003 17:48:56 -0000 Received: from ras3-31.pipcom.com (HELO new) (204.92.62.163) by bree.pipcom.com with SMTP; 23 Sep 2003 17:48:56 -0000 Message-ID: <010d01c381fa$93a24c00$0b3cfea9@new> From: "Peter Cowan/Lexy Cameron" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Power on a cold day was Re: [FlyRotary] Re:Some turbo thoughts from a pro .... Date: Tue, 23 Sep 2003 13:42:53 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0107_01C381D8.96AC5020" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_0107_01C381D8.96AC5020 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Jim would that perhaps be 33. feet perminute? Peter Subject: [FlyRotary] Re: Power on a cold day was Re: [FlyRotary] = Re:Some turbo thoughts from a pro .... <... density change is proportional to the change in absolute temp, so = 10F is about 2% ...> True. But that 2% increase in power is ALL EXCESS THRUST (over and = above what it takes to hold exactly what you've got - say 90 kts and = 1000 fpm climb). Two hp would be 66000 #'/min which with a 2000# = airplane produces 3300 fpm rate of climb - ABOVE what you started with = !! Of course not every spec of that extra power gets to the prop, but = you can see how what appears to be a modest power increase can produce = results that are apparently way out of proportion to change in power.=20 Just a theory .... Jim S.=20 =20 Al Gietzen wrote:=20 Rusty, the rotary engine (for what ever reason) just = LOOOVVVVVEEEESSS those cooler days. I have had fuel flow of over 20 gph = on take off when OAT was 28F. That calculates out to over 200HP, static = RPM was 5800 rpm vice a nominal of 5200 on a "normal" day. I've never = said anything about it because 1. Who would believe me 2. Who would = believe me? and 3. Who would believe me? Anytime the OAT is below 65F = or so my static RPM increases about 200 rpm for ever 10F further temp = drop. Ed;=20 The only problems with this is 1. I don't believe it, 2. I don't = believe it; and 3, I find it hard to believe J.=20 The air density change is proportional to the change in absolute = temp, so 10F is about 2%. Maybe 3 hp? Gee, we don't really need to = turbo because the adiabatic temp drop with altitude will overcome the = loss of power due to altitude J. Could there be some other effect going = on here? Fuel density is also changing. How are you measuring fuel = flow. =20 One problem with hp inferred from fuel burn is that we know that = the rotary's don't burn all that fuel to make power. Fuel is burning = right on out into the exhaust pipe, and the amount of unburned fuel = varies with a lot of other factors. =20 Al --=20 Jim Sower=20 Crossville, TN; Chapter 5=20 Long-EZ N83RT, Velocity N4095T=20 =20 ------=_NextPart_000_0107_01C381D8.96AC5020 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Jim would that perhaps be 33. feet=20 perminute?

Peter

Subject: [FlyRotary] Re: Power = on a cold=20 day was Re: [FlyRotary] Re:Some turbo thoughts from a pro ....

<... density change is proportional to the change in = absolute temp,=20 so 10F is about 2% = ...>

True. But=20 that 2% increase in power is ALL EXCESS THRUST (over and above what it = takes=20 to hold exactly what you've got - say 90 kts and 1000 fpm = climb). Two hp=20 would be 66000 #'/min which with a 2000# airplane produces 3300 fpm = rate of=20 climb - ABOVE what you started with !! Of course not every spec = of that=20 extra power gets to the prop, but you can see how what appears to be a = modest=20 power increase can produce results that are apparently way out of = proportion=20 to change in power.
Just a theory .... Jim S.
=20
Al Gietzen wrote:=20

Rusty, the rotary engine (for what = ever=20 reason) just LOOOVVVVVEEEESSS those cooler days. I have had = fuel=20 flow of over 20 gph on take off when OAT was 28F. That = calculates=20 out to over 200HP, static RPM was 5800 rpm vice a nominal of 5200 = on a=20 "normal" day. I've never said anything about it because = 1. Who=20 would believe me 2. Who would believe me? and 3. Who would = believe=20 me? Anytime the OAT is below 65F or so my static RPM = increases=20 about 200 rpm for ever 10F further temp drop.

Ed;=20

The only = problems with this=20 is 1. I don=92t believe it, 2. I don=92t believe it; and 3, I find = it hard to=20 believe J.=20
The air = density change is=20 proportional to the change in absolute temp, so 10F is about = 2%. Maybe 3 hp? Gee, we don=92t really need to turbo = because the=20 adiabatic temp drop with altitude will overcome the loss of power = due to=20 altitude J. Could there be some other effect going on here? = Fuel=20 density is also changing. How are you measuring fuel=20 flow. =20

One problem = with hp=20 inferred from fuel burn is that we know that the rotary=92s = don=92t burn all=20 that fuel to make power. Fuel is burning right on out into = the=20 exhaust pipe, and the amount of unburned fuel varies with a lot of = other=20 factors. =20

Al

--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, = Velocity=20 N4095T

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