X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 15 May 2005 21:14:03 -0400 Message-ID: X-Original-Return-Path: Received: from HQEMGATE01.nvidia.com ([216.228.112.170] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 945261 for lml@lancaironline.net; Sun, 15 May 2005 20:49:54 -0400 Received-SPF: neutral receiver=logan.com; client-ip=216.228.112.170; envelope-from=colyncase@earthlink.net Received: from hqemfe03.nvidia.com (Not Verified[172.16.227.123]) by HQEMGATE01.nvidia.com id ; Sun, 15 May 2005 17:49:06 -0700 Received: from thelma.nvidia.com ([172.16.228.84]) by hqemfe03.nvidia.com with Microsoft SMTPSVC(6.0.3790.211); Sun, 15 May 2005 17:49:07 -0700 Received: from ccaselt (cvpn2-4-113.nvidia.com [10.2.4.113]) by thelma.nvidia.com (8.8.8+Sun/8.8.8) with SMTP id RAA27325 for ; Sun, 15 May 2005 17:49:06 -0700 (PDT) X-Original-Message-ID: <003d01c559b1$106fc110$7104020a@nvidia.com> From: "colyncase on earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Crash Safety X-Original-Date: Sun, 15 May 2005 17:49:05 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003A_01C55976.63642E50" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Original-Return-Path: colyncase@earthlink.net X-OriginalArrivalTime: 16 May 2005 00:49:07.0729 (UTC) FILETIME=[10E28010:01C559B1] This is a multi-part message in MIME format. ------=_NextPart_000_003A_01C55976.63642E50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Brent, =20 It does seem that doing something to prevent the fuel from spewing = out of the fuel lines would be useful for some crash scenarios. Do you = know of some kind of automatic valve or limiting device one could put at = the wing root without screwing up the fuel pressure for normal = operation? I'm also wondering how those discriminating valves work. Are they = active or passive? Colyn Case ----- Original Message -----=20 From: Brent Regan=20 To: Lancair Mailing List=20 Sent: Sunday, May 15, 2005 5:31 PM Subject: [LML] Re: Crash Safety Terrance brings up an interesting point. Post crash fires are = apparently responsible for many fatalities. I suspect that the exact = number of fatalities that can be attributed directly to the post crash = fire is difficult to determine as a crash survivor may be fatally = injured but alive at the time of the fire. I do not think there is an = effective solution for fuel carried in the wings but, armoring fuel = carried in the passenger compartment may be desirable. Race cars achieve fuel safety by limiting the amount of fuel on board, = holding the fuel in a foam filled rubberized fuel bladder, placing that = bladder within the protective structure of the car and (in the case of = formula cars) adding energy absorbing material (aluminum honeycomb) to = the nose of the car. Race car fuel vents are typically large diameter as = rapid fueling is usually a requirement. The fuel vents feature a = Discriminator Valve that will allow air to pass but will close in the = presence of fluids. In human physiology this functionality is provided = by the anal sphincter.=20 Implementing effective race car type fuel safety in an airplane is = problematic because it would involve one or more of; increased cost, = increased weight, reduced range and increased maintenance. In a IV or = ES you would need roughly 22 unique fuel bladders that would require = interconnections (fuel and vent) and be removable via access hatches for = maintenance. Since wings are sometimes "removed" during accidents, the = individual bladders would need to maintain their integrity and the fuel = and vent lines would need to seal. Bladders have been used in aircraft = applications. Many spam cans use them and, in one Lancair case, I was = involved in the design of a bladder tank that was installed in the back = seat of a IV to provide additional fuel for transoceanic flights. Back in the 1970s and '80s research was conducted to investigate = adding aluminum foam to the fuel tanks of airliners. The foam would = limit the vaporization rate of the fuel and therefore limit the fire = expansion rate. This research culminated in the radio controlled crash = of an airliner in the desert. Unfortunately, because of poor = controllability, one of the jet's engines struck the "wing rippers" = installed on the runway and the hot engine parts defeated the foam = suppression. A spectacular fireball ensued. Bummer. My gut tells me that adding fuel bladders to the wings will have only = a limited effect on safety and be prohibitively expensive to install and = maintain. The increased opportunity of a fuel leak (and loss) may = actually increase the probability of an accident even if decreasing the = probability of a post crash fire.=20 The header tank is another matter altogether. I don't think it is ever = a good idea to have large quantities of flammable or hot fluids in the = passenger compartment. If you must have fuel in the passenger = compartment then armoring against taking a 100LL shower is a good thing. = Regards Brent Regan ------=_NextPart_000_003A_01C55976.63642E50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Brent,  
    It does seem that = doing=20 something to prevent the fuel from spewing out of the fuel lines would = be useful=20 for some crash scenarios.  Do you know of some kind of automatic = valve or=20 limiting device one could put at the wing root without screwing up the = fuel=20 pressure for normal operation?
    I'm also wondering = how those=20 discriminating valves work.  Are they active or = passive?
 
Colyn Case
 
----- Original Message -----
From:=20 Brent=20 Regan
Sent: Sunday, May 15, 2005 5:31 = PM
Subject: [LML] Re: Crash = Safety

Terrance brings up an interesting = point. Post=20 crash fires are apparently responsible for many fatalities. I suspect = that the=20 exact number of fatalities that can be attributed directly to the post = crash=20 fire is difficult to determine as a crash survivor may be fatally = injured but=20 alive at the time of the fire.  I do not think there is an = effective=20 solution for fuel carried in the wings but, armoring fuel carried in = the=20 passenger compartment may be desirable.

Race cars achieve fuel = safety=20 by limiting the amount of fuel on board, holding the fuel in a foam = filled=20 rubberized fuel bladder, placing that bladder within the protective = structure=20 of the car and (in the case of formula cars) adding energy absorbing = material=20 (aluminum honeycomb) to the nose of the car. Race car fuel vents are = typically=20 large diameter as rapid fueling is usually a requirement. The fuel = vents=20 feature a Discriminator Valve that will allow air to pass but will = close in=20 the presence of fluids. In human physiology this functionality is = provided by=20 the anal sphincter.

Implementing effective race car type fuel = safety=20 in an airplane is problematic because it would involve one or more of; = increased cost, increased weight, reduced range and increased=20 maintenance.  In a IV or ES you would need roughly 22 unique fuel = bladders that would require interconnections (fuel and vent) and be = removable=20 via access hatches for maintenance. Since wings are sometimes = "removed" during=20 accidents, the individual bladders would need to maintain their = integrity and=20 the fuel and vent lines would need to seal.  Bladders have been = used in=20 aircraft applications. Many spam cans use them and, in one Lancair = case, I was=20 involved in the design of a bladder tank that was installed in the = back seat=20 of a IV to provide additional fuel for transoceanic = flights.

Back in=20 the 1970s and '80s research was conducted to investigate adding = aluminum foam=20 to the fuel tanks of airliners. The foam would limit the vaporization = rate of=20 the fuel and therefore limit the fire expansion rate.  This = research=20 culminated in the radio controlled crash of an airliner in the desert. = Unfortunately, because of poor controllability, one of the jet's = engines=20 struck the  "wing rippers" installed on the runway  and the = hot=20 engine parts defeated the foam suppression. A spectacular fireball = ensued.=20 Bummer.

My gut tells me that adding fuel bladders to the wings = will=20 have only a limited effect on safety and be prohibitively expensive to = install=20 and maintain. The increased opportunity of a fuel leak (and loss) may = actually=20 increase the probability of an accident even if decreasing the = probability of=20 a post crash fire.

The header tank is another matter = altogether. I=20 don't think it is ever a good idea to have large quantities of = flammable or=20 hot fluids in the passenger compartment. If you must have fuel in the=20 passenger compartment then armoring against taking a 100LL shower is a = good=20 thing.

Regards
Brent = Regan
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