Return-Path: Received: from rokland5.awh.us ([67.15.10.31] verified) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP-TLS id 743778 for flyrotary@lancaironline.net; Thu, 17 Feb 2005 21:30:46 -0500 Received-SPF: none receiver=logan.com; client-ip=67.15.10.31; envelope-from=bob@bob-white.com Received: from bgp01386375bgs.brodwy01.nm.comcast.net ([68.35.160.229]:34126 helo=quail) by rokland5.awh.us with smtp (Exim 4.43) id 1D1xu2-00069z-2y for flyrotary@lancaironline.net; Thu, 17 Feb 2005 20:29:58 -0600 Date: Thu, 17 Feb 2005 19:29:56 -0700 From: Bob White To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Returnless Fuel System - Fuel Cooler Message-Id: <20050217192956.7d3f2522.bob@bob-white.com> In-Reply-To: References: X-Mailer: Sylpheed version 1.9.2 (GTK+ 2.4.9; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Antivirus-Scanner: Clean mail though you should still use an Antivirus X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - rokland5.awh.us X-AntiAbuse: Original Domain - lancaironline.net X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - bob-white.com X-Source: X-Source-Args: X-Source-Dir: Hi Leon, Thanks for the comments. This is the first response I've seen where the 1/4 inch line was addressed. I certainly don't have any practical knowledge about what is needed, but was concerned that the 1/4 was too small. My thought was that at idle, I'm pushing fuel into the rail with a 3/8 inch line and the regulator has to dump almost all of it back to the tank thru the 1/4 inch line. It seemed to me that that could mess up the pressure regulation. If you tell me it's OK, then I'll connect it up that way first. I just consider Todd a bad infulence on me. First with EWP's, then the returnless fuel system. :) I should be getting some preliminary data on my EWP's in a few days. Even those cold climates can produce some pretty hot weather occasionally. My wife is from North Dakota where 20 F below isn't too uncommon, but summer days can easily be in the 90's F (just not many of them). I would have to go to Phoenix on a bad day to see your 50 C temps, or maybe Carlsbad, NM. Bob White On Fri, 18 Feb 2005 12:52:08 +1100 "Leon" wrote: > Hey Guys, > > I'm sort of having trouble believing that this discussion is still going on > about returnless systems. Why?? Todd probably gets away with his system > because > he lives in a REALLY cold climate. He would DEFINITELY have SERIOUS > problems in the 50 Deg C heat we regularly expereience on the tarmac here in > Oz in summer. But then again, maybe Lamar IS correct, and that I AM a > lunatic!! > . > For the power output that most of you have (less than 250 BHP), a 5/16" > high > pressure supply line is more than adequate, and a 1/4" return line is more > than adequate. For bigger power output (Hi Boost 13B & 20B engines, say up > to 400 Cheveaux) and a Hi Flo EFI pump , maybe a 3/8" supply line, and a > 5/16" return line. > > Whenever I do a turbo engine conversion on ROAD GOING early model RX7 > ('79-"85), I just use the stock fuel lines (5/16" supply & 1/4 return), > and I have never have a problem. One EFI pump is sufficient. The > only reason we have 2 x HP pumps on an aircraft is redundancy in case one > fails at take-off and climb-out. > > However, the size of the return line is not really that critical. All it is > there for is to take the flow from the dumped pressure from the HP pump. If > you are using the same pump as a car, then you only need the same size > return. > Interestingly, on the Mazda RX7 turbo cars, they have a 2 stage control > (via voltage) of the EFI pump to cut the return flow at low load, and boost > the supply at high load.. > > The SIZE of the return line is not really so much an issue as actually > having one - size is more of an issue with the supply line, but only with > Mega-Pferd turbo engines. The issue is that so long as there is a return > line so that > the fuel continues to circulate back to the tank, and if that tank is in > the breeze, the fuel will never get hot. > > If the fuel is returned to the header / surge tank, this MUST be vented > back to the main tank. Otherwise you will get air/vapour locks. If there > is a breeze directed over the header/surge tank, then why do you need a $40 > cooler?? As a famous megalomaniac once said, "It's either them or us" > (referring to issues of mental stability). > I'm just totally flummoxed. > > As Tracy said below, the cooler is just a bandaid covering up a problem. > It also scares me witless when I read what Tracy wrote below about a > fatality actually occuring because of dicey fuel supply issues. > > So please, ... this is a plea, just follow normal EFI practice. > Have a look at the Toyota PDF link somebody posted a while ago about both > return & returnless systems. Stick to the return system. This is the way > it MUST be done. Please DON'T > try to re-invent something that doesn't need to be re-invented, and that > has been proven to work on millions of EFI road cars, and thousands and > thousands of race cars. > > Additionally, that SDS link I posted the other day details how to do it > where there are multiple tanks involved. There is a "critical minimum > complexity" in any system. Try and simplify the system any further beyond > this "critical minimum complexity", then the system no longer works > properly, and will come back and bite you REALLY hard on your nethermost > parts when you least expect it! > > Cheers, > > Leon > > > ----- Original Message ----- > From: "Bob White" > To: "Rotary motors in aircraft" > Sent: Friday, February 18, 2005 2:29 AM > Subject: [FlyRotary] Re: Returnless Fuel System - Fuel Cooler > > > > > > Hi Tracy, > > > > My alternative is to try to jam all the return fuel thru a 1/4 inch > > line. It seems like that will cause problems also. It's fairly > > substantial surgery to get a 3/8 inch return line in. > > > > I certainly agree that without the cooler it's a disaster waiting to > > happen. I'm relying somewhat on Todd's positive experiences > > with his system, and further testing on my plane. > > > > Bob White > > > > On Thu, 17 Feb 2005 09:52:56 -0500 > > "Tracy Crook" wrote: > > > > > Even with the cooler, This scares me. I know of at least 2 cases > where it has caused power failures, one resulted in fatality. True, they > didn't have the cooler but it is a bandaid covering up a problem. > > > > > > Tracy > > > > > > Hi Jim, > > > > > > Todd's system is a "quasi" returnless system. The fuel is returned to > > > the input of the fuel pump instead of the tank. Without the cooler, > > > much of the same fuel would circulate thru the fuel rail again and > agin > > > picking up heat. To see Todd's diagram and description go to: > > > > > > http://www.rotarywiki.com/ and search for > "returnless". > > > > > > Bob White > > > > > > > > > On Wed, 16 Feb 2005 23:25:06 -0600 > > > Jim Sower > > wrote: > > > > > > > But I thought the purpose of the cooler was to cool the *return* > fuel. > > > > If it's a one-way system, how does the fuel get hot enough to need > cooling? > > > > What am I missing here? ... Jim S. > > > > > > > > Bob White wrote: > > > > > > > > >Todd, > > > > > > > > > >I'm going to build a returnless system based on your design. I > found > > > > >this fuel cooler at Jeg's for about $40. Jeg's P/N 771-1009. The > > > > >finned area is 4.5 X 5 X 7/8 (inch), which I think is a little > bigger > > > > >than the one you made. > > > > > > > > > > >http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=3532&prmenbr= > 361 > > > > > > > > > >I'm sure it's nicer looking than anything I could build myself. > I'll > > > > >post pictures of my alternator bracket one of these days to prove > it. > > > > > > > > > >Bob White > > > > > > > > > > > > > > > > > > > > > > > >> Homepage: http://www.flyrotary.com/ > > > > >> Archive: > http://lancaironline.net/lists/flyrotary/List.html > > > > > > > > > > > > > > > > > -- > > > http://www.bob-white.com > > > N93BD - Rotary Powered BD-4 (real soon) > > > > > > >> Homepage: http://www.flyrotary.com/ > > > >> Archive: > http://lancaironline.net/lists/flyrotary/List.html > > > > > > > > > -- > > http://www.bob-white.com > > N93BD - Rotary Powered BD-4 (real soon) > > > > >> Homepage: http://www.flyrotary.com/ > > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html > > -- http://www.bob-white.com N93BD - Rotary Powered BD-4 (real soon)