Return-Path: Received: from [65.54.168.120] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 573265 for flyrotary@lancaironline.net; Sun, 19 Dec 2004 15:46:26 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.168.120; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 19 Dec 2004 12:45:01 -0800 Message-ID: Received: from 65.54.97.152 by BAY3-DAV16.phx.gbl with DAV; Sun, 19 Dec 2004 20:44:34 +0000 X-Originating-IP: [65.54.97.152] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Short intake & George Graham update Date: Sun, 19 Dec 2004 15:41:53 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0148_01C4E5E1.439950E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0009.2900 Seal-Send-Time: Sun, 19 Dec 2004 15:41:53 -0500 X-OriginalArrivalTime: 19 Dec 2004 20:45:01.0344 (UTC) FILETIME=[9C3C4200:01C4E60B] This is a multi-part message in MIME format. ------=_NextPart_000_0148_01C4E5E1.439950E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I should have added that the short & medium short manifolds were tested = using the 2.85 : 1 gear drive and rpm range was 1000 rpm higher than = when I used the 2.176 : 1 drive. Results would probably not be quite as = good with the lower rpm range. =20 Keep in mind that the long vs short runner issue has very little to do = with performance in cruise, it just doesn't mater that much there. = Especially if you are not at WOT in cruise (most rotaries are throttled = back here) Climb and top speed will be most affected by intake tuning. = To put some numbers to this, I made 160 HP at 6000 with a virtually = untuned system using carbs. With pretty good tuned EFI I made 180 HP at = 6250 (same prop, so more rpm made part of the increase). These figures = on 2.176 : 1 gear drive. George Graham, one of the early aviation rotary adopters, isn't on the = list so though I'd pass along his latest. After 200+ hours, his second = Mazda manual transmission (2nd gear) PSRU stripped it's gears and he = dead sticked safely on a road about 10 miles from Leesburg Fl yesterday. = No damage to him or plane but he doesn't want to take a chance on the = transmission again. I'll be building him an RD-1A. He glided about 20 = miles from an altitude of only 5000 ft with the prop freewheeling! = I've heard several times that a freewheeling prop (no engine drag on it) = would generate lots of drag. Another sacred cow shot down : ) Tracy=20 Tracy Crook wrote: Should be an interesting experiment Paul, can't wait to hear = results. I tried a very short and now a medium-short manifold and find that = it works well IF it is very "clean" (proper diameter runners, no change = in cross sectional area, well matched to ports, etc, etc) The very = short runners gave up some power at climb rpm (FP prop) but did OK at = cruise & top end. The Medium-short version works about as well as my = long (so-so clean) manifold (~17" runners) and real good at top end. FWIW, my guess about your dripping throttle body is condensation on = the runners & throttle body walls. Gravity does the rest. Agravating = the problem is the "cool side injectors". Someone called this = arrangement the "Holy Grail" of intake design. I'd call it the "Sacred = Cow". Tracy ( eat sacred cow for lunch). ----- Original Message -----=20 From: Paul=20 Subject: [FlyRotary] Re: Short intake manifolds Hi, Tom....I saved a few posts that addressed the problem you were = referring=20 to. The folks at Mistral also went into a lot of detail about it. = Problem=20 is, they were talking about the LONG intake runners, and having = the=20 injectors at the far end, away from the engine. Power pulses = problems,=20 incorrect fuel mixtures, etc. I am not going to try the short manifold, (since I received = one with=20 the bolt-on fuel/ignition package that I purchased from Atkins = Rotary), and=20 see how it works. I understand Dave Atkins has been using his for = quite some=20 time, with a lot of cross-country trips under his belt. Also, hearing Al's comments helps as well. What the heck....I = built an=20 experimental, so I guess it's expected I have the need to = experiment a=20 little. Thanks for the input, Tom. Paul Conner ----- Original Message -----=20 From: "Tom" > To: "Rotary motors in aircraft" = > Sent: Tuesday, December 14, 2004 11:36 PM Subject: [FlyRotary] Re: Short intake manifolds > Paul, > There was a discussion here a few weeks ago regarding 'back = pulses' in the > intake manifold. Sorry, that may not be the correct term. = IIRC, seems a > short manifold may have issues, one being fuel droplets being = expelled=20 > the > opposite direction. Let me suggest the potential for it to = pool in your > 'outer chamber' and another potential for a backfire to ignite = it.=20 > Hopefully > that is blatantly wrong so those who know will step in and = straighten it=20 > out. > You can tell by my terminology that I don't talk motors much. = Also, seems=20 > I > read many years ago that the one reason aircraft carburetors are = hung=20 > below the > motor is so any fuel remnants would fall out and evaporate and = not pool, > lessening chances that a backfire would have something to = ignite. This,=20 > just > idle chat. > > Tom > > > --- Paul > = wrote: >> My question is....With the >> short manifold putting the TWM throttlebody over the top of the = exhaust,=20 >> has >> Dave had any problems with fuel dripping out of the = throttlebody after >> engine shutdown? Also, did he put any kind of heat barrier = between the >> exhaust manifold and the throttlebody? > > > > __________________________________ > Do you Yahoo!? > Send holiday email and support a worthy cause. Do good. > = http://celebrity.mail.yahoo.com > >>> Homepage: = http://www.flyrotary.com/ >>> Archive: = http://lancaironline.net/lists/flyrotary/List.html >=20 >> Homepage: = http://www.flyrotary.com/ >> Archive: = http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0148_01C4E5E1.439950E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I should have added that the short & medium short manifolds = were tested=20 using the 2.85 : 1 gear drive and rpm range was 1000 rpm higher than = when I used=20 the 2.176 : 1 drive.  Results would probably not be quite as good = with the=20 lower rpm range. 
 
Keep in mind that the long vs short runner issue has very=20 little to do with performance in cruise, it just doesn't mater that = much=20 there.  Especially if you are not at WOT in cruise (most = rotaries are=20 throttled back here)  Climb and top speed will be most affected by=20 intake tuning. 
 
To put some numbers to this, I made 160 HP at 6000 with a virtually = untuned=20 system using carbs.  With pretty good tuned EFI I made 180 HP at = 6250 (same=20 prop, so more rpm made part of the increase).  These figures on = 2.176 : 1=20 gear drive.
 
George Graham, one of the early aviation rotary adopters, isn't on = the list=20 so though I'd pass along his latest.  After 200+ hours, his second = Mazda=20 manual transmission (2nd gear) PSRU stripped it's gears and he dead = sticked=20 safely on a road about 10 miles from Leesburg Fl yesterday.  No = damage to=20 him or plane but he doesn't want to take a chance on the transmission=20 again.  I'll be building him an RD-1A.  He glided about = 20 miles=20 from an altitude of only 5000 ft with the prop=20 freewheeling!   I've heard several times that = a freewheeling=20 prop (no engine drag on it) would generate lots of drag.  = Another=20 sacred cow shot down : )
 
Tracy
Tracy=20 Crook wrote:
Should be an interesting experiment Paul,  can't wait to = hear=20 results.
 
 I tried a very short and now a medium-short manifold and = find=20 that it works well IF it is very "clean" (proper diameter runners, = no change=20 in cross sectional area, well matched to ports, etc, etc)  The = very=20 short runners gave up some power at climb rpm (FP prop) but did OK = at cruise=20 & top end.  The Medium-short version works about as well as = my long=20 (so-so clean) manifold (~17" runners)  and real good at top = end.
 
FWIW, my guess about your dripping throttle body is = condensation on the=20 runners & throttle body walls.  Gravity does the = rest. =20 Agravating the problem is the "cool side injectors".  Someone = called=20 this arrangement the "Holy Grail" of intake design.   I'd = call it=20 the "Sacred Cow".
 
Tracy   ( eat sacred cow for lunch).
-----=20 Original Message -----
From:=20 Paul
Subject:=20 [FlyRotary] Re: Short intake manifolds

Hi, Tom....I saved a few posts that addressed the = problem=20 you were referring
to. The folks at Mistral also went into a = lot of=20 detail about it. Problem
is, they were talking about the LONG = intake=20 runners, and having the
injectors at the far end, away from = the=20 engine. Power pulses problems,
incorrect fuel mixtures,=20 etc.
     I am not going to try the short = manifold,=20 (since I received one with
the bolt-on fuel/ignition package = that I=20 purchased from Atkins Rotary), and
see how it works. I = understand Dave=20 Atkins has been using his for quite some
time, with a lot of=20 cross-country trips under his belt.
    Also, = hearing=20 Al's comments helps as well.  What the heck....I built an=20
experimental, so I guess it's expected I have the need to = experiment a=20
little. Thanks for the input, Tom.  Paul = Conner

-----=20 Original Message -----
From: "Tom" <tomtugan@yahoo.com>
To: = "Rotary=20 motors in aircraft" <flyrotary@lancaironline.net>
Sent:=20 Tuesday, December 14, 2004 11:36 PM
Subject: [FlyRotary] Re: = Short=20 intake manifolds


> Paul,
> There was a = discussion here=20 a few weeks ago regarding 'back pulses' in the
> intake=20 manifold.  Sorry, that may not be the correct = term.   IIRC,=20 seems a
> short manifold  may have issues, one being = fuel=20 droplets being expelled
> the
> opposite=20 direction.   Let me suggest the potential for it to pool = in=20 your
> 'outer chamber' and another potential for a backfire = to=20 ignite it.
> Hopefully
> that is blatantly wrong so = those who=20 know will step in and straighten it
> out.
> You can = tell by=20 my terminology that I don't talk motors much.  Also, seems =
>=20 I
> read many years ago that the one reason aircraft = carburetors are=20 hung
> below the
> motor is so any fuel remnants = would fall=20 out and evaporate and not pool,
> lessening chances that a = backfire=20 would have something to ignite.  This,
> just
> = idle=20 chat.
>
> Tom
>
>
> --- Paul <sqpilot@bellsouth.net>=20 wrote:
>>  My question is....With the
>> = short=20 manifold putting the TWM throttlebody over the top of the exhaust, =
>> has
>> Dave had any problems with fuel = dripping out=20 of the throttlebody after
>> engine shutdown?  Also, = did he=20 put any kind of heat barrier between the
>> exhaust = manifold and=20 the throttlebody?
>
>
>
>=20 __________________________________
> Do you Yahoo!?
> = Send=20 holiday email and support a worthy cause. Do good.
> http://celebrity.mail.yahoo.com<= /A>
>
>>> =20 Homepage:  http://www.flyrotary.com/
>&= gt;> =20 Archive:   http://lancai= ronline.net/lists/flyrotary/List.html
>=20



>>  Homepage:  http://www.flyrotary.com/
>&= gt; =20 Archive:   http://lancai= ronline.net/lists/flyrotary/List.html

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