X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 25 Sep 2007 16:43:02 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m25.mx.aol.com ([64.12.137.6] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2351260 for lml@lancaironline.net; Tue, 25 Sep 2007 15:04:20 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.6; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m25.mx.aol.com (mail_out_v38_r9.2.) id q.c17.1ee7769f (65097) for ; Tue, 25 Sep 2007 15:03:32 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Tue, 25 Sep 2007 15:03:32 EDT Subject: Re: [LML] Re: Lancair 320 aircraft jacks X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1190747012" X-Mailer: AOL 9.0 VR sub 165 X-Spam-Flag: NO -------------------------------1190747012 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 9/25/2007 12:25:39 P.M. Central Daylight Time, Christopher.Zavatson@baesystems.com writes: This design has an unstable mode that folks should be aware of. Fortunately, it isn't very difficult to eliminate. To be stable you always want the load to be distributed to the two feet on each end of the stand. With the current design, this indeed occurs while the telescoping section is pinned. The load is distributed out the four legs (upper right sketch). However, while bottle jacks are used to raise the plane, the load path is no longer through the legs but instead from the plane straight down through the bottle jack to the floor (upper left sketch). This isn't too bad if only one side at a time is jacked up. Some fore/aft stability is provided by the other side and/or the wheels still on the ground. It gets a little dicey when both left and right side are being hoisted at the same time, the plane could fall forward or aft because none of the four jack stand legs are supporting the plane. One could theoretically crawl under the plane and lift the stand right off the floor. To be stable while hoisting the plane, the forces need a path through the structure of the stand (lower center sketch). Placing the bottle jack on an additional beam between the two legs provides this path. Chris, Egads, I have constructed a similar jack, but a little bit different. I used 2 inch square steel tubing and 1.5 inch square tubing for the sliders in the vertical tubing pieces (overbuilt, just like my Lancair). There is an area washer welded to the top of the slider for a bigger base that the wing rests upon with the jack locating "knob" fitting in the washer hole. Also, there is a thin steel plate welded between the feet on each side and electric scissor screw jacks (12 VDC, $50 each) are machine screwed to those sheets. Since I only use the jack for my plane, the cross piece, connecting the two sides, is bolted in place. This jack is rigid in every direction. I still have the jigs for the cutting and welding up such a jack (already used by another to construct one of their own. I searched my computer for pix, but could not find them so I will take a few and send them out along with a parts list. Each side is infinitely adjustable thus allowing for lateral leveling - all done with push button ease. BTW, it is painted with old out-of-date two-part tank sealer. I considered putting the jack on wheels, but the smarter side of my brain said, "No!" Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Darwinian culling phrase: Watch This! ************************************** See what's new at http://www.aol.com -------------------------------1190747012 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 9/25/2007 12:25:39 P.M. Central Daylight Time,=20 Christopher.Zavatson@baesystems.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#0000ff size= =3D2>
This design has an unstable mode that folks shoul= d be=20 aware of.  Fortunately, it isn't very difficult to=20 eliminate.  To be stable you always want the load to be distributed t= o=20 the two feet on each end of the stand.  With the current design, this= =20 indeed occurs while the telescoping section is pinned.  The load is=20 distributed out the four legs (upper right sketch).  However, wh= ile=20 bottle jacks are used to raise the plane, the load path is no longer throu= gh=20 the legs but instead from the plane straight down through the bottle jack=20= to=20 the floor (upper left sketch).  This isn't too bad if only one s= ide=20 at a time is jacked up. Some fore/aft stability is provided by the ot= her=20 side and/or the wheels still on the ground.  It gets a=20 little dicey when both left and right side are being hoisted at=20= the=20 same time, the plane could fall forward or aft because none of the=20 four jack stand legs are supporting the plane.  One could=20 theoretically crawl under the plane and lift the stand right off the=20 floor.  To be stable while hoisting the plane, the forces need a= =20 path through the structure of the stand (lower center=20 sketch).  Placing the bottle jack on an additional beam bet= ween=20 the two legs provides this=20 path.  
Chris,
 
Egads, I have constructed a similar jack, but a little bit different.&n= bsp;=20 I used 2 inch square steel tubing and 1.5 inch square tubing for the=20 sliders in the vertical tubing pieces (overbuilt, just like my Lancair).&nbs= p;=20 There is an area washer welded to the top of the slider for a bigger base th= at=20 the wing rests upon with the jack locating "knob" fitting in the washer=20 hole.  Also, there is a thin steel plate welded between the feet o= n=20 each side and electric scissor screw jacks (12 VDC, $50 each) = ;are=20 machine screwed to those sheets.  Since I only use the jack for my plan= e,=20 the cross piece, connecting the two sides, is bolted in place.  Th= is=20 jack is rigid in every direction.  I still have the jigs for the cuttin= g=20 and welding up such a jack (already used by another to construct one of= =20 their own.  I searched my computer for pix, but could not find them so=20= I=20 will take a few and send them out along with a parts list.  E= ach=20 side is infinitely adjustable thus allowing for lateral leveling - all done=20= with=20 push button ease.  BTW, it is painted with old out-of-date two-part tan= k=20 sealer.
 
I considered putting the jack on wheels, but the smarter side of my bra= in=20 said, "No!"
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

Darwinian culling phrase: Watch=20 This!



See what's ne= w at AOL.com a= nd Make AOL Your Homepage.
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