Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2908778 for flyrotary@lancaironline.net; Sun, 28 Dec 2003 22:41:17 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hBT3fCow025906 for ; Sun, 28 Dec 2003 22:41:15 -0500 (EST) Message-ID: <001001c3cdbd$372cc5e0$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Coolers Date: Sun, 28 Dec 2003 22:38:24 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01C3CD93.4E02D180" 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 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_000D_01C3CD93.4E02D180 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Ed; Fortunately our airport is very ideal for flight testing, with 3 = separate, long runways and a relatively low amount of traffic. I try to = do my flights when there is little traffic and I always maintain gliding = distance to a runway. One of the benefits of the turbocharger and the = constant =20 SNIP I think that by ducting cool air through a fuel cooler at the = inlet to the shroud around the fuel components, it should adequately = cool the fuel without significantly heating the cooling air allowing = plenty of cooling for the pumps and filters. I just have to find a small = enough cooler to do the job. I also use a gascolator on one of my fuel = lines, which I'm considering removing. I have water drains on each tank = and a sump with a drain on my header tank, so I've never seen a single = drop of water when draining my gascolator.=20 How large is your cooling duct to your shroud over the fuel pumps? = Where do you have your inlet for this cooling air? I originally = considered ducting from the rad inlets, but I don't want to be stealing = any of this cooling air, so am considering a small NACA duct on the = side. =20 My shroud is fed by a 2" dia scatt hose that route air from a small = NACA scope (about the same size as on the side of an RV aircraft) the = duct opening is under the cowl about 2/3 of the way back from the front. = I concluded that during high power climb would be when I would need the = cooling air the worst. Seems to work for me. Interesting, I have had = two power out events - but, neither due to fuel/vapor lock {:>). = INterestingly, its not high power that is generally the problem. At = high power, you generally do not recirculate much fuel, much more of it = is being consumed and replaced with new fresh cool fuel. Its after you = throttle back after a hard climb and stay a lower airspeeds like in the = pattern, then much more fuel is recirculated back to the headertank (and = bringing with it the heat build up). =20 Should it happen again, I would suggest opening the throttle wide = open. This would tend to quickly get rid of either the fuel vapor or = heated fuel as the injector remains open longer. The engine would of = course, cought and sputter until the fuel flow returned to normal, but = it just might get enough cool fuel back into the tank to help. On the = other hand, I believe you have a much larger header tank than I do, so = if your fuel got to that point, it would take much longer to restore = conditions than my less than 1 quart header tank. Quick to empty and = quick to fill. Leon has sent me an off-line reply with a few additional suggestions = as well. I'm considering replumbing the header tank vent line (which is = normally closed), back to one of the wing tanks, instead of to the vent = line header. This would allow the boost pump to continually recirc cool = fuel to the header tank rather than just pressurizing it. This would = also allow me to close this vent/recirc line when I do want to = pressurize the header tank. Sounds like a reasonable approach. The reason that I originally opted to use a header tank was it = seemed at first to be the simplest way to manage 6 fuel tanks without = the hassle of returning to a single tank and transferring fuel as others = have done. I've now found that it requires much more management than = anticipated and is becoming much more complicated. If I was starting = over again, I would certainly reconsider this idea.=20 That is also why I went the same route. Simplicity and only one valve = to be concerned with. But, clearly there are risks associated with it. = I have over 200 hours and never had the engine quite (due to heated = fuel), but my smaller header tank might mean there is less of a resovior = of heated fuel and vapors, so corrective action may bring quicker = results. Just some thought. Sounds like a great airport for test flights! Stay alert out there! Ed Anderson ------=_NextPart_000_000D_01C3CD93.4E02D180 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 Hi Ed;
    Fortunately our airport = is very=20 ideal for flight testing, with 3 separate, long runways and a = relatively low=20 amount of traffic. I try to do my flights when there is little traffic = and I=20 always maintain gliding distance to a runway. One of the = benefits of=20 the turbocharger and the constant 
 
SNIP
 
    I think that by ducting cool air through a = fuel=20 cooler at the inlet to the shroud around the fuel components, it = should=20 adequately cool the fuel without significantly heating the cooling air = allowing plenty of cooling for the pumps and filters. I just have to = find a=20 small enough cooler to do the job. I also use a gascolator on one of = my fuel=20 lines, which I'm considering removing. I have water drains on each = tank and a=20 sump with a drain on my header tank, so I've never seen a single drop = of water=20 when draining my gascolator.
    How large is your cooling duct to your shroud = over the=20 fuel pumps? Where do you have your inlet for this cooling air? I=20 originally considered ducting from the rad inlets, but I don't want to = be=20 stealing any of this cooling air, so am considering a small NACA duct = on the=20 side.
   
My = shroud is fed=20 by a 2" dia scatt hose that route air from a small NACA scope (about = the same=20 size as on the side of an RV aircraft) the duct opening is under the = cowl=20 about 2/3 of the way back from the front.  I concluded that = during high=20 power climb would be when I would need the cooling air the = worst.  Seems=20 to work for me.  Interesting, I have had two power out events - = but,=20 neither due to fuel/vapor lock {:>).  INterestingly, its not = high=20 power that is generally the problem.  At high power, you = generally do not=20 recirculate much fuel, much more of it is being consumed and replaced = with new=20 fresh cool fuel.  Its after you throttle back after a hard climb = and stay=20 a lower airspeeds like in the pattern, then much more fuel is = recirculated=20 back to the headertank (and bringing with it the heat build = up).  =20
 
  Should it=20 happen again, I would suggest opening the throttle wide open.  = This would=20 tend to quickly get rid of either the fuel vapor or heated fuel = as the=20 injector remains open longer.  The engine would of course, cought = and=20 sputter until the fuel flow returned to normal, but it just might get = enough=20 cool fuel back into the tank to help.  On the other hand, I = believe you=20 have a much larger header tank than I do, so if your fuel got to that = point,=20 it would take much longer to restore conditions than my less than 1 = quart=20 header tank.  Quick to empty and quick to = fill.
 
 Leon has sent me an off-line reply with a few additional = suggestions as=20 well. I'm considering replumbing the header tank vent line (which is = normally=20 closed), back to one of the wing tanks, instead of to the vent line = header.=20 This would allow the boost pump to continually recirc cool fuel to the = header=20 tank rather than just pressurizing it. This would also allow me to = close this=20 vent/recirc line when I do want to pressurize the header=20 tank.
 
Sounds like=20 a reasonable approach.
 
    The reason that I originally opted to use a = header tank=20 was it seemed at first to be the simplest way to manage 6 fuel tanks = without=20 the hassle of returning to a single tank and transferring fuel as = others have=20 done. I've now found that it requires much more management than = anticipated=20 and is becoming much more complicated. If I was starting over = again, I=20 would certainly reconsider this idea.
 
 
That = is also why I=20 went the same route.  Simplicity and only one valve to be = concerned=20 with.  But, clearly there are risks associated with it.  I = have over=20 200 hours and never had the engine quite (due to heated fuel), but my = smaller=20 header tank might mean there is less of a resovior of heated fuel and = vapors,=20 so corrective action may bring quicker results.  Just some=20 thought.
 
Sounds like a=20 great airport for test flights!
 
Stay = alert out=20 there!
 
Ed=20 Anderson
 
 
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