Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Mon, 10 Jan 2005 20:32:31 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d06.mx.aol.com ([205.188.157.38] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 601803 for lml@lancaironline.net; Mon, 10 Jan 2005 11:19:23 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.38; envelope-from=MikeEasley@aol.com Received: from MikeEasley@aol.com by imo-d06.mx.aol.com (mail_out_v37_r3.8.) id q.198.35f24073 (1320) for ; Mon, 10 Jan 2005 11:19:03 -0500 (EST) From: MikeEasley@aol.com X-Original-Message-ID: <198.35f24073.2f1404f6@aol.com> X-Original-Date: Mon, 10 Jan 2005 11:19:02 EST Subject: Re: [LML] Re: gross weights X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1105373942" X-Mailer: 9.0 Security Edition for Windows sub 5000 -------------------------------1105373942 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Eric Lindbergh's Columbia was flight tested to 4260 lbs. It had a fuel capacity of 310 gal. That's about 30 lbs/sq ft. wing loading at takeoff. I believe the landing lights were removed from the leading edges of the wings to allow for fuel bays to be installed. Lancair described it as a "stock 300", except for the modifications for additional fuel. It was expected to land in Paris with about 65 gal. of fuel. That would put it within normal limits for landing. Lancair press releases describe "extensive heavy testing" that was done before delivery to Erik. The key here is "testing". You need to test. I think the structure of the airframe is not the issue with increased weights. It's the aerodynamics that can jump up and bite you. Takeoff and landing distances, approach speeds, etc, all need to be tested at various CGs. It is highly unlikely that a 10% increase in max. gross will introduce any unexpected characteristics. But the farther you go, the more you have a chance of discovering a "surprise". Extrapolating outside the test envelope using formulas, or simply guessing, is not wise. Something to keep in mind, certified birds in the normal category are designed to withstand +3.8g to -1.5g. So every pound you add to your gross weight requires ~4 lbs. of extra structural strength. Certified birds have a balked landing climb requirement that requires that an airplane climb in fpm at 10 times the stall speed in mph in the take-off configuration at sea level. Our Lancairs would have no trouble passing the test with weights above recommended gross. But I think this test is what determines the max. gross on most factory aircraft. Mike -------------------------------1105373942 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Eric Lindbergh's Columbia was flight tested to 4260 lbs. It had a= =20 fuel capacity of 310 gal. That's about 30 lbs/sq ft. wing loading at=20 takeoff. I believe the landing lights were removed from the leading ed= ges=20 of the wings to allow for fuel bays to be installed. Lancair described= it=20 as a "stock 300", except for the modifications for additional fuel. It= was=20 expected to land in Paris with about 65 gal. of fuel. That would put i= t=20 within normal limits for landing.

Lancair press releases describe "extensive heavy testing" that was done= =20 before delivery to Erik. The key here is "testing". You need to=20 test.

I think the structure of the airframe is not the issue with increased=20 weights. It's the aerodynamics that can jump up and bite you. =20 Takeoff and landing distances, approach speeds, etc, all need to be tested a= t=20 various CGs. It is highly unlikely that a 10% increase in ma= x.=20 gross will introduce any unexpected characteristics. But the fart= her=20 you go, the more you have a chance of discovering a "surprise". =20 Extrapolating outside the test envelope using formulas, or simply guessing,=20= is=20 not wise.

Something to keep in mind, certified birds in the normal category are=20 designed to withstand +3.8g to -1.5g. So every pound you add to your g= ross=20 weight requires ~4 lbs. of extra structural strength.

Certified birds have a balked landing climb requirement that requires t= hat=20 an airplane climb in fpm at 10 times the stall speed in mph in the take-off=20 configuration at sea level. Our Lancairs would have no trouble passing= the=20 test with weights above recommended gross. But I think this test is=20 what determines the max. gross on most factory aircraft.

Mike

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