Return-Path: Received: from ms-smtp-01.southeast.rr.com ([24.93.67.82] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2590508 for flyrotary@lancaironline.net; Tue, 23 Sep 2003 07:47:46 -0400 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-01.southeast.rr.com (8.12.5/8.12.2) with SMTP id h8NBeI0R009056 for ; Tue, 23 Sep 2003 07:40:19 -0400 (EDT) Message-ID: <004c01c381c8$31750220$1702a8c0@WorkGroup> From: "Ed Anderson" 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 07:45:31 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0049_01C381A6.AA310780" 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_0049_01C381A6.AA310780 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 23, 2003 1:05 AM Subject: [FlyRotary] Re: Power on a cold day was Re: [FlyRotary] Re: = Some turbo thoughts from a pro .... 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; 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. 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 See! I knew I wouldn't be believed {:>). You are not alone. When, = I first mentioned it to Tracy, he suggested a Tach malfunction {:<(.=20 First, I abolutely agree, Al that the increased in power that = would move my static rpm from 5200 to 5800 rpm on a cold day, could of = only had a small contribution from the colder denser air. Once, I = elimnated a possible tach malfuction at high rpm, that increased power = puzzle is part of what got me started on this DIE analysis. It is now = clear to me how and why that additional power was there on cold days, = but not on the warmer days. In fact, in my presentation in October at = Shady Bend, I use that the equations to explain exactly how and why that = was happening to my engine. I also agree that you can crank up the mixture and fuel flow and the = rotary will simply spite out and burn in the exhaust the excess fuel. = However, when the fuel burn rate, the engine rpm and the aircraft = performance all three indicate increased power...there just might be = increased power. But, given that the power increase was real (and despite the opinon = of unbelievers {:>) I believe it was) then the next question is how can = I get it all the time, not just on cold days. That is what I am now = working on. Ed Anderson ------=_NextPart_000_0049_01C381A6.AA310780 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Tuesday, September 23, = 2003 1:05=20 AM
Subject: [FlyRotary] Re: Power = on a cold=20 day was Re: [FlyRotary] Re: Some turbo thoughts from a pro ....

 

Rusty, the = rotary engine=20 (for what ever reason) just LOOOVVVVVEEEESSS those cooler = days.  I have=20 had fuel flow of over 20 gph on take off when OAT was 28F.  = That=20 calculates out to over 200HP, static RPM was 5800 rpm vice a nominal = of 5200=20 on a "normal" day.  I've never said anything about it because = 1. =20 Who 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;

 

The = only problems=20 with this is 1. I don=92t believe it, 2. I don=92t believe it; and = 3, I find it=20 hard to believe J.

The air = density=20 change is proportional to the change in absolute temp, so 10F is = about =20 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=20 some other effect going on here? Fuel density is also = changing.  How=20 are you measuring fuel flow.

 

 One problem=20 with hp inferred from fuel burn is that we know that the rotary=92s = don=92t burn=20 all 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. 

 

Al

 

See! I = knew I=20 wouldn't be believed {:>).  You are not alone.  When, I = first=20 mentioned it to Tracy, he suggested a Tach malfunction=20 {:<(. 

 

 First, I=20 abolutely agree, Al that the  increased in power that = would move=20 my static rpm from 5200 to 5800 rpm on a cold day, could of only had = a small=20 contribution from the colder denser air.  Once, I elimnated a = possible=20 tach malfuction at high rpm, that increased power puzzle is part of = what got=20 me started on this DIE analysis.  It is now clear to me how and = why=20 that additional power was there on cold days, but not on the warmer=20 days.  In fact, in my presentation in October at Shady Bend, I = use that=20 the equations to explain exactly how and why that was happening to = my=20 engine.

 

I also = agree that=20 you can crank up the mixture and fuel flow and the rotary will = simply spite=20 out and burn in the exhaust the excess fuel.  However, when the = fuel=20 burn rate, the engine rpm and the aircraft performance all three = indicate=20 increased power...there just might be increased = power.

 

But, = given that=20 the power increase was real (and despite the opinon of unbelievers = {:>) I=20 believe it was) then the next question is how can I get it all the = time, not=20 just on cold days.  That is what I am now working = on.

 

Ed=20 Anderson

 

 

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