X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 03 Jan 2011 14:21:55 -0500 Message-ID: X-Original-Return-Path: Received: from imr-ma01.mx.aol.com ([64.12.206.39] verified) by logan.com (CommuniGate Pro SMTP 5.3.11) with ESMTP id 4662341 for lml@lancaironline.net; Mon, 03 Jan 2011 09:35:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.39; envelope-from=MikeEasley@aol.com Received: from mtaomg-ma03.r1000.mx.aol.com (mtaomg-ma03.r1000.mx.aol.com [172.29.41.10]) by imr-ma01.mx.aol.com (8.14.1/8.14.1) with ESMTP id p03EYRrp008591 for ; Mon, 3 Jan 2011 09:34:27 -0500 Received: from core-mkb004c.r1000.mail.aol.com (core-mkb004.r1000.mail.aol.com [172.29.98.13]) by mtaomg-ma03.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 93AD2E00009C for ; Mon, 3 Jan 2011 09:34:27 -0500 (EST) From: MikeEasley@aol.com X-Original-Message-ID: <59472.12b6e7a6.3a533873@aol.com> X-Original-Date: Mon, 3 Jan 2011 09:34:27 -0500 (EST) Subject: Re: [LML] Fuel Dumping X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_59472.12b6e7a6.3a533873_boundary" X-Mailer: AOL 9.5 sub 5401 X-AOL-IP: 75.71.55.189 X-Originating-IP: [172.29.31.35] x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:358554080:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d290a4d21de736eb0 --part1_59472.12b6e7a6.3a533873_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit It seems that the nature of the fuel tank failure would determine whether you need to dump fuel or not to prevent a fire. Do Lancairs have fuel tank ruptures (big hole) or wing separation (small hole) in an off airport landing/crash? If the wing separated, you'd have a small 3/4" hole leaking fuel which would be a much smaller fire than a wing that breaks into the fuel bay and dumps most of the fuel instantly. I'm sure each model of Lancair has different wing structural characteristics that affect how vulnerable the fuel bays are in a crash. The ES has its main spar aft of the fuel bay. The forward spar extends to the outboard rib of the fuel bay (standard 92 gals. fuel). That seems to protect the fuel bay somewhat if you caught a wingtip and ripped off the wing outboard section. I know a lot of the IV guys have fuel in every nook and cranny av ailable in the wings which makes the fuel bays much more susceptible to failure in a crash. Mike Easley Colorado Springs In a message dated 1/3/2011 6:36:15 A.M. Mountain Standard Time, rwolf99@aol.com writes: The only reason I'm aware of why designers include a fuel dump capability is when they design a landing gear system which cannot handle the maxmum takeoff gross weight. This is often the cse on large jets -- think of an airliner which may have a gross weight double that of its typical landing weight. In this case, a landing required immediately after takeoff would require a fuel dump, which could easily be a 15 minute process. I know of no cases where designers include a fuel dump provision to reduce post crash fires. That's not to say the idea is without merit, but I would not bother with it. Instead, I would take measures to prevent inadvertent fuel release after a survivable crash. I'm not sure how to do that -- would a flexible fuel line (say, steel braided) be less likely to tear than a hard aluminum line? Would a silicone fireproofed fuel line be less likely to rupture (those puppies look pretty indestructible)? What about a header tank -- I imagine that five gallons of fuel just above your knees is not a good place for a fuel leak (and yes, my airplane has the header tank). But dumping the fuel before an off-airport landing? I don't think I would do that, but that's just me. - Rob Wolf p.s. the NASA test in the early 1980's involved a remotely-piloted Convair 720 with an anti-misting additive in the fuel. As I recall, the remotely piloted airplane did not hit the intended point on laning and thus the objects intended to puncture the tanks, well, ithey pretty much ripped the wings apart, releasing the fuel all at once. This was a test failure and the explosion-inhibiting anti-mist additive was not adequately tested. Needless to say, they did not repeat the test. _http://en.wikipedia.org/wiki/Controlled_Impact_Demonstration_ (http://en.wikipedia.org/wiki/Controlled_Impact_Demonstration) --part1_59472.12b6e7a6.3a533873_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
It seems that the nature of the fuel tank failure would determine whet= her=20 you need to dump fuel or not to prevent a fire.  Do Lancairs have fuel= tank=20 ruptures (big hole) or wing separation (small hole) in an off airport=20 landing/crash?  If the wing separated, you'd have a small 3/4" hole le= aking=20 fuel which would be a much smaller fire than a wing that breaks into the fu= el=20 bay and dumps most of the fuel instantly.
 
I'm sure each model of Lancair has different wing structural=20 characteristics that affect how vulnerable the fuel bays are in a= =20 crash.  The ES has its main spar aft of the fuel bay.  The forwar= d=20 spar extends to the outboard rib of the fuel bay (standard 92 gals. fuel).&= nbsp;=20 That seems to protect the fuel bay somewhat if you caught a wingtip and rip= ped=20 off the wing outboard section.  I know a lot of the IV guys have fuel = in=20 every nook and cranny available in the wings which makes the fuel bays= much=20 more susceptible to failure in a crash.
 
Mike Easley
Colorado Springs
 
In a message dated 1/3/2011 6:36:15 A.M. Mountain Standard Time,=20 rwolf99@aol.com writes:
The only reason I'm aware of why designers include a fuel dump capab= ility=20 is when they design a landing gear system which cannot handle the maxmum= =20 takeoff gross weight.  This is often the cse on large jets -- think = of an=20 airliner which may have a gross weight double that of its typical la= nding=20 weight.  In this case, a landing required immediately after takeoff = would=20 require a fuel dump, which could easily be a 15 minute process.
 
I know of no cases where designers include a fuel dump provision to= =20 reduce post crash fires.  That's not to say the idea is without meri= t,=20 but I would not bother with it.  Instead, I would take measures to= =20 prevent inadvertent fuel release after a survivable crash.  I'm not = sure=20 how to do that -- would a flexible fuel line (say, steel braided) be= less=20 likely to tear than a hard aluminum line?  Would a silicone fireproo= fed=20 fuel line be less likely to rupture (those puppies look pretty=20 indestructible)?  What about a header tank -- I imagine that five ga= llons=20 of fuel just above your knees is not a good place for a fuel leak (and ye= s, my=20 airplane has the header tank).
 
But dumping the fuel before an off-airport landing?  I don't th= ink I=20 would do that, but that's just me.
 
- Rob Wolf
 
p.s. the NASA test in the early 1980's involved a remotely-piloted= =20 Convair 720 with an anti-misting additive in the fuel.  As I recall,= the=20 remotely piloted airplane did not hit the intended point on laning and th= us=20 the objects intended to puncture the tanks, well, ithey pretty much rippe= d the=20 wings apart, releasing the fuel all at once.  This was a test failur= e and=20 the explosion-inhibiting anti-mist additive was not adequately tested.&nb= sp;=20 Needless to say, they did not repeat the test.
 
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