Return-Path: Received: from [216.52.245.18] (HELO ispwestemail1.aceweb.net) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2580390 for flyrotary@lancaironline.net; Mon, 15 Sep 2003 15:52:11 -0400 Received: from ispwest.com (unverified [127.0.0.1]) by ispwestemail1.aceweb.net (Vircom SMTPRS 2.1.258) with ESMTP id for ; Mon, 15 Sep 2003 12:54:54 -0700 Message-ID: X-EM-APIVersion: 2, 0, 1, 0 X-Priority: 3 (Normal) From: "Bill Schertz" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Good news, Bad news Date: Mon, 15 Sep 2003 12:54:54 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_84815C5ABAF209EF376268C8" ------=_NextPart_84815C5ABAF209EF376268C8 Content-type: text/html; charset=US-ASCII Content-Transfer-Encoding: quoted-printable = Message
Rusty,
Consider the following=2E
 
If you had a 'supercharger' (belt driven) instead of a turbocharger, yo= u=20 would agree that the supercharger is sucking power from the engine to do it'= s=20 job=2E  Friend of mine has one, and estimates that it takes about 30=20= horsepower to run the supercharger=2E  If you were driving this superch= arger=20 , and keeping the manifold pressure to 30", then you would be getting *less*=20= power from the engine-supercharger combination than a NA engine=2E
 
The same may be happening with your turbocharger=2E  It is sucking= power=20 by increasing exhaust backpressure, but you are restricting the manifold=20 pressure that needs to be higher in order to generate more power=2E You have= to=20 generate your net power *plus* the work the TC is doing=2E
 
Does this make any sense to you?
Bill Schertz
KIS Crui= ser # 4045


----- Original Message --= ---
From: Russell Duffy
Sent: 9/15/2003 9:36:44 AM
To: flyrotary@lancai= ronline=2Enet
Subject: [FlyRotary] Re:= Good news, Bad news

1=2E The BUC is draggy, even worse t= han=20 we thought (but doesn't really explain the lousy climb rate)

This is a given, and the new cowl is being mentall= y=20 designed as I type=2E

2=2E The Warp Drive prop is never go= ing=20 to be an optimum high speed stick=2E (but hell, you're not even to moderate=20= speed yet) My gut feel is that you should be running at least 17 degrees=20= at tip=2E Anything less than 16 is a waste of time unless you are resigned=20= to flying a draggy RV-3 which I'm sure you are not=2E This is assuming abou= t=20 a 68 - 69" prop length=2E

Your gut feeling is pretty accurate=2E Warp=20 originally estimated that I'd need 18 degree (3 blade, 68") for a 200 HP=20= engine=2E I just got off the phone with them, and they're going to be=20 calling back later today with some real numbers=2E Off the top of his head,=20= he said these sound a whole lot like what the gyro guys get with their 120=20= HP Subaru's=2E Sadly, that's about what I expected to hear, but I=20 guess the good news is that I may have identified the largest issue=2E =20 The turbo's really becoming more trouble than it's worth (Tracy, this is=20 where you say "I told you so")=2E =20

3=2E Your CG is near the fwd=2E limi= t which=20 generates a LOT of trim drag=2E

4=2E You may be underestimating the=20= effect of gearleg & wheel fairings (I think you mentioned you don't=20 have them yet) I found that I could not make ANY final decisions on=20 airframe/engine performance, prop pitch or even cooling until these were in=20= place=2E

On the RV-8, the gear fairings and pants made abou= t 12 kts=20 difference at cruise speed, but didn't change climb performance that I=20 could tell=2E

Turbo stuff:
I have no turbo experience but my best gues= s is=20 that the air temp sensor should be up-wind of the turbo=2E Let the MAP tabl= e=20 programming take care of the temp rise due to adabiatic (Sp?) heating from t= he=20 turbo=2E This should work at low levels of boost like you are running=20 and will eliminate the big mixture difference between A & B=20 controllers=2E With this setup in a worst case scenario, the mixture might=20= go too rich at high boost, a much better thing than too lean=2E

I'll have to think about this some=2E You're correct that it=20 would be the safer way to go=2E On the 3rd gen, the temp sensor is in the=20= intake manifold, which is a large chunk of aluminum=2E Unfortunately,=20 the sensor isn't well isolated from the heat of the manifold itself, so it t= ends=20 to read the heat of the manifold almost as much as the air that passes throu= gh=20 it=2E One almost certain way to blow up an engine is to drive=20 your car for a while in the winter, then park it for a few minutes=2E =20 By the time you get back in, the temp sensor is reading some really high, he= at=20 soaked temp, and will continue doing so for about the first 10 minutes of=20= driving=2E The air getting to the engine is freezing cold, so when=20 you jump on the throttle, you get fuel to go with 150 degrees, but have 30=20= degree air=2E Boost + lean mixture =3D new apex seals, and maybe new=20 turbos=2E

Thanks,
Rusty

------=_NextPart_84815C5ABAF209EF376268C8 Content-type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Rusty, Consider the following=2E If you had a 'supercharger' (belt driven) = instead of a turbocharger, you would agree that the supercharger is sucking power fr= om the engine to do it's job=2E Friend of mine has one, and estimates that it take= s about 30 horsepower to run the supercharger=2E If you were driving this superchar= ger , and keeping the manifold pressure to 30", then you would be getting *less* p= ower from the engine-supercharger combination than a NA engine=2E The same may b= e happening with your turbocharger=2E It is sucking power by increasing exhaust backpre= ssure, but you are restricting the manifold pressure that needs to be higher in ord= er to generate more power=2E You have to generate your net power *plus* the work t= he TC is doing=2E Does this make any sense to you? Bill Schertz KIS Cruiser # 4045=20 ----- Original Message ----- From: Russell Duffy Sent: 9/15/2003 9:36:44 AM = To: flyrotary@lancaironline=2Enet Subject: [FlyRotary] Re: Good news, Bad news=20= 1=2E The BUC is draggy, even worse than we thought (but doesn't really expla= in the lousy climb rate)=20 This is a given, and the new cowl is being mentally designed as I type=2E=20= 2=2E The Warp Drive prop is never going to be an optimum high speed stick=2E= (but hell, you're not even to moderate speed yet) My gut feel is that you should be run= ning at least 17 degrees at tip=2E Anything less than 16 is a waste of time unles= s you are resigned to flying a draggy RV-3 which I'm sure you are not=2E This is a= ssuming about a 68 - 69" prop length=2E=20 Your gut feeling is pretty accurate=2E Warp originally estimated that I'd ne= ed 18 degree (3 blade, 68") for a 200 HP engine=2E I just got off the phone with t= hem, and they're going to be calling back later today with some real numbers=2E Off t= he top of his head, he said these sound a whole lot like what the gyro guys get wit= h their 120 HP Subaru's=2E Sadly, that's about what I expected to hear, but I guess = the good news is that I may have identified the largest issue=2E The turbo's really b= ecoming more trouble than it's=20worth (Tracy, this is where you say "I told you so"= )=2E=20 3=2E Your CG is near the fwd=2E limit which generates a LOT of trim drag=2E=20= 4=2E You may be underestimating the effect of gearleg &wheel fairings (I thi= nk you mentioned you don't have them yet) I found that I could not make ANY final d= ecisions on airframe/engine performance, prop pitch or even cooling until these were = in place=2E On the RV-8, the gear fairings and pants made about 12 kts difference at cru= ise speed, but didn't change climb performance that I could tell=2E=20 Turbo stuff: I have no turbo experience but my best guess is that the air te= mp sensor should be up-wind of the turbo=2E Let the MAP table programming take care of= the temp rise due to adabiatic (Sp?) heating from the turbo=2E This should work at lo= w levels of boost like you are running and will eliminate the big mixture difference = between A &B controllers=2E With this setup in a worst case scenario, the mixture mi= ght go too rich at high boost, a much better thing than too lean=2E=20 I'll have to think about this some=2E You're correct that it would be the sa= fer way to go=2E On the 3rd gen, the temp sensor is in the intake manifold, which is= a large chunk of aluminum=2E Unfortunately, the sensor isn't well isolated from the = heat of the manifold itself, so it tends to read the heat of the manifold almost as = much as the air that passes through it=2E One almost certain way to blow up an en= gine is to drive your car for a while in the winter, then park it for a few minutes=2E= By the time you get back in, the temp sensor is reading some really high, heat = soaked temp, and will continue doing so for about the first 10 minutes of driving=2E= The air getting to the engine is freezing cold, so when you jump on the throttle= , you get fuel to go with 150 degrees, but have 30 degree air=2E Boost + lean mixt= ure =3D new apex seals, and maybe new turbos=2E=20 Thanks, Rusty=20 ------=_NextPart_84815C5ABAF209EF376268C8--