X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 12 Mar 2007 13:47:25 -0400 Message-ID: X-Original-Return-Path: Received: from [206.246.194.60] (HELO visi.net) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1916478 for lml@lancaironline.net; Mon, 12 Mar 2007 09:29:32 -0400 Received-SPF: none receiver=logan.com; client-ip=206.246.194.60; envelope-from=rpastusek@htii.com X-Virus-Scanner-Engine: ClamAV X-Virus-Scanner: cgpav Received: from [68.34.115.162] (HELO DLHTPAX009) by visi.net (CommuniGate Pro SMTP 4.2) with ESMTP id 199102251 for lml@lancaironline.net; Mon, 12 Mar 2007 08:28:19 -0500 From: "Robert Pastusek" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Re: enough runway" X-Original-Date: Mon, 12 Mar 2007 09:28:22 -0400 X-Original-Message-ID: <003501c764aa$50497dc0$f0dc7940$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0036_01C76488.C937DDC0" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcdkK0u2OJt7rIJbQCGEGa7aGBBxCgAfBaug Content-Language: en-us This is a multipart message in MIME format. ------=_NextPart_000_0036_01C76488.C937DDC0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit James wrote: .I envisage this method only as an emergency measure to avert disaster if one has to land on too short a field or too slick a surface (or, Grayhawk, experience brake failure). Preventing overrun is optimal, but even reducing overrun impact speed could reduce injuries and damage. James, Drag chutes are optimally effective at high speed just at/after touchdown. When we used them in military fighters, we always planned to deploy them at/just after touchdown-and to jettison them if they caused directional control problems as with a wet runway/crosswind. By the time the F-4 Phantom was down to 80 kts or so, you couldn't even detect that it had been jettisoned by the deceleration of the aircraft. Of course, a larger chute, relative to the aircraft weight, would be effective to a lower speed. There are a number of other considerations: You'll want to strengthen the rear fuselage and provide a reinforced mounting place to secure the "pulling end" of the chute when deployed. This adds weight beyond the chute itself, well back in the tail area. Consider accidental deployment. On the ground it makes a mess; in the air, it could be fatal...so you'll probably want a way to jettison it? Proper design/engineering/testing will help with these issues, but it's not a matter of simply bolting something that looks about right back near the tail and setting off. Another consideration is repacking. If you use it, it has to be repacked and that can be messy/time consuming. If you don't use it regularly, it definitely needs to be opened and re-packed regularly or it won't work when you need it. I once re-packed my own F-4 drag chute on a deployment when no maintenance folks were available to help. Unfortunately, I failed to secure it properly in the compartment, so when we landed at Kadena, it just blossomed normally and settled on the runway-where our #2 promptly ran over it. No one was hurt in the ensuing mess, but it was a good lesson for me.these things are not the panacea they might first appear to be. Just some things to think about. Bob Pastusek ------=_NextPart_000_0036_01C76488.C937DDC0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

James wrote:

 

…I envisage this method only as an emergency measure to avert disaster if = one has to land on too short a field or too slick a surface (or, Grayhawk, = experience brake failure). Preventing overrun is optimal, but even reducing overrun = impact speed could reduce injuries and damage. 

 

James,

Drag chutes are optimally effective at high speed just = at/after touchdown. When we used them in military fighters, we always planned to = deploy them at/just after touchdown—and to jettison them if they caused directional control problems as with a wet runway/crosswind. By the time = the F-4 Phantom was down to 80 kts or so, you couldn’t even detect = that it had been jettisoned by the deceleration of the aircraft. Of course, a = larger chute, relative to the aircraft weight, would be effective to a lower = speed.

 

There are a number of other considerations: You’ll = want to strengthen the rear fuselage and provide a reinforced mounting place to = secure the “pulling end” of the chute when deployed. This adds = weight beyond the chute itself, well back in the tail area. Consider accidental deployment. On the ground it makes a mess; in the air, it could be = fatal...so you’ll probably want a way to jettison it? Proper = design/engineering/testing will help with these issues, but it’s not a matter of simply = bolting something that looks about right back near  the tail and setting = off… Another consideration is repacking. If you use it, it has to be repacked = and that can be messy/time consuming. If you don’t use it regularly, = it definitely needs to be opened and re-packed regularly or it won’t work when = you need it. I once re-packed my own F-4 drag chute on a deployment when no = maintenance folks were available to help. Unfortunately, I failed to secure it = properly in the compartment, so when we landed at Kadena, it just blossomed normally = and settled on the runway—where our #2 promptly ran over it. No one = was hurt in the ensuing mess, but it was a good lesson for me…these things = are not the panacea they might first appear to be… Just some things to = think about.

 

Bob Pastusek

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