Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Tue, 18 Jan 2005 16:47:07 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d03.mx.aol.com ([205.188.157.35] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 612179 for lml@lancaironline.net; Tue, 18 Jan 2005 16:41:02 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.35; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d03.mx.aol.com (mail_out_v37_r3.8.) id q.54.3bf4dfde (2519) for ; Tue, 18 Jan 2005 16:40:29 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <54.3bf4dfde.2f1edc4a@aol.com> X-Original-Date: Tue, 18 Jan 2005 16:40:26 EST Subject: Re: [LML] Knots - not X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1106084426" X-Mailer: 9.0 Security Edition for Windows sub 5000 -------------------------------1106084426 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 1/18/2005 6:59:43 A.M. Central Standard Time, domcrain@pacific.net.au writes: For example, my aircraft stalls in the approach config. at 64 knots after a MTOW. So near enough to max weight of 816 Kgs (1800 lbs). That is a minimum approach of 83 KNOTS. Pucker factor means I approach at 90 KNOTS, and bleed to 85 over the fence. Dom, Comparisons between homebuilts are interesting at best. I have talked to many 320/360 builders where the initial weigh-in differs as to where fuselage stations are (FS), weight distribution on each of the wheels and the final calculated arms for pilot, fuel, etc. Sometimes, the empty weight CG is suspect. This would seem to be relevant at stall. It would be nice for all of us to use Kts - after all, it is the modern generally accepted standard for aviation. But, no one reports Calibrated Air Speed, a more useful number. Some of us have done our best to find this number at various speeds and if we have the Rocky Mountain Instrument's (RMI) Micro-encoder, it can be adjusted so that KIAS is very close to KCAS. Using KTAS and a GPS derived KTAS, a correction factor can be determined- RMI computes KTAS, accounting for compressibility's affect (miniscule at low air speeds) on the true air temperature and using pressure altitude - other computers may not. Modern GPS units are quite accurate and there are several techniques available for determining the derived KTAS. Usually, the largest inaccuracy of a pitot/static air speed system is at a high angle of attack - like close to stall. However, I generally fly much like you do on approach, as confirmed by an AOA indication. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Fair and Balanced Opinions at No Charge! There is an oxymoron in that, somewhere... -------------------------------1106084426 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 1/18/2005 6:59:43 A.M. Central Standard Time,=20 domcrain@pacific.net.au writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3D"Trebuchet MS" color=3D#000= 000=20 size=3D3>

For example, my aircraft stalls in=20= the=20 approach config. at 64 knots after a MTOW. So n= ear=20 enough to max weight of 816 Kgs (1800 lbs).

That is a minimum approach of 83=20 KNOTS.

Pucker factor means I approach at 9= 0 KNOTS,=20 and bleed to 85 over the=20 fence.

Dom,

Comparisons between homebuilts are interesting at best. I ha= ve=20 talked to many 320/360 builders where the initial weigh-in differs as to whe= re=20 fuselage stations are (FS), weight distribution on each of the wheels a= nd=20 the final calculated arms for pilot, fuel, etc. Sometimes, the empty=20 weight CG is suspect. This would seem to be relevant at stall.

It would be nice for all of us to use Kts - after all, it is the modern= =20 generally accepted standard for aviation. But, no one reports=20 Calibrated Air Speed, a more useful number. Some of us have done our b= est=20 to find this number at various speeds and if we have the Rocky Mountain=20 Instrument's (RMI) Micro-encoder, it can be adjusted so=20= that=20 KIAS is very close to KCAS. Using KTAS and a GPS derived KTAS, a=20 correction factor can be determined- RMI computes KTAS, accounting for=20 compressibility's affect (miniscule at low air speeds) on the true air=20 temperature and using pressure altitude - other computers may not. Mod= ern=20 GPS units are quite accurate and there are several techniques available for=20 determining the derived KTAS.

Usually, the largest inaccuracy of a pitot/static air speed system is a= t a=20 high angle of attack - like close to stall.

However, I generally fly much like you do on approach, as confirmed by=20= an=20 AOA indication.=20

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)

Fai= r=20 and Balanced Opinions at No Charge!
There is an oxymoron in that,=20 somewhere...

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