X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 27 May 2006 23:13:19 -0400 Message-ID: X-Original-Return-Path: Received: from web34913.mail.mud.yahoo.com ([209.191.68.192] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with SMTP id 1130054 for lml@lancaironline.net; Sat, 27 May 2006 04:56:25 -0400 Received-SPF: none receiver=logan.com; client-ip=209.191.68.192; envelope-from=n103md@yahoo.com Received: (qmail 29805 invoked by uid 60001); 27 May 2006 08:55:39 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=zhBPsmOUZ7+2WWVZX8E8g+CLojUBmFrIekorIFR2lWWMfMi+9z1qCpA3ulVhPzp5OwdQQY2glvfOPbh3ChgWBeTQD0hzK3zetfHFv7VS/g030WPf+0WldPHqshMrYWsWb/orgWBK5CTFur2LkkseAhDh+pRV3YBD7pbJGIBkEyM= ; X-Original-Message-ID: <20060527085539.29803.qmail@web34913.mail.mud.yahoo.com> Received: from [69.12.132.145] by web34913.mail.mud.yahoo.com via HTTP; Sat, 27 May 2006 01:55:39 PDT X-Original-Date: Sat, 27 May 2006 01:55:39 -0700 (PDT) From: bob mackey Subject: Re: How Not to Do 1st Runup X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1379768829-1148720139=:27397" Content-Transfer-Encoding: 8bit --0-1379768829-1148720139=:27397 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit If the gear locks fail when pushed by hand, or by thrust from the prop, then they will fail just as easily when using the brakes on the runway. Braking should be able to generate a force aft at the tire about equal the weight on the tire. Call if half the gross weight. Usual design practices call for 3G loads on the landing gear. If that vertical load is to be applied while also using maximum braking, then each gear leg should therefore be able to take an aft load of at least 1.5 times the gross weight: (3550 lbs/1G) * 3(G) / 2 (wheels/main gear) = 5325 lbs. I doubt that any of the engine/prop combinations for the Lancair 4 generate over 5000 lbs of thrust, so it would appear that either the landing gear in the video was faulty or poorly designed (or both). That's not to say that that the test crew in the video didn't make other mistakes like forgetting to tie the airplane to the ground or check to see if the landing gear was functional. --------------------------------- Be a chatter box. Enjoy free PC-to-PC calls with Yahoo! Messenger with Voice. --0-1379768829-1148720139=:27397 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit If the gear locks fail when pushed by hand, or by thrust from the prop,
then they will fail just as easily when using the brakes on the runway.

Braking should be able to generate a force aft at the tire about
equal the weight on the tire. Call if half the gross weight. Usual
design practices call for 3G loads on the landing gear. If that vertical
load is to be applied while also using maximum braking, then
each gear leg should therefore be able to take an aft load of at
least 1.5 times the gross weight:

(3550 lbs/1G) * 3(G) /  2  (wheels/main gear)  = 5325 lbs.

I doubt that any of the engine/prop combinations for the Lancair 4
generate over 5000 lbs of thrust, so it would appear that either the
landing gear in the video was faulty or poorly designed (or both).

That's not to say that that the test crew in the video didn't make other
mistakes like forgetting to tie the airplane to the ground or check to
see if the landing gear was functional.


Be a chatter box. Enjoy free PC-to-PC calls with Yahoo! Messenger with Voice. --0-1379768829-1148720139=:27397--