X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 09 Dec 2009 08:12:15 -0500 Message-ID: X-Original-Return-Path: Received: from [66.70.126.15] (HELO omta0113.mta.everyone.net) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTP id 4011922 for lml@lancaironline.net; Wed, 09 Dec 2009 07:46:29 -0500 Received-SPF: none receiver=logan.com; client-ip=66.70.126.15; envelope-from=bknotts@buckeye-express.com Received: from dm0219.mta.everyone.net (sj1-slb03-gw2 [172.16.1.96]) by omta0113.mta.everyone.net (Postfix) with ESMTP id 42FEC17501B2 for ; Wed, 9 Dec 2009 04:45:54 -0800 (PST) X-Eon-Dm: dm0219 Received: by dm0219.mta.everyone.net (EON-AUTHRELAY2 - 1835a6bc) id dm0219.4b185e19.1e3b61 for ; Wed, 9 Dec 2009 04:41:25 -0800 X-Eon-Sig: AQK8DXBLH5r1cQ5mMwIAAAAB,7b1c54786c66769bbfba72f453250a82 X-Original-Message-ID: <4B1F9C0A.5010602@buckeye-express.com> X-Original-Date: Wed, 09 Dec 2009 07:46:02 -0500 From: "F. Barry Knotts" Reply-To: bknotts884@earthlink.net User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 X-Original-To: Lancair Mailing List Subject: Re: [LML] Vne discussion References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------060501060704070709020305" This is a multi-part message in MIME format. --------------060501060704070709020305 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit I haven't seen much on Mmo. In fact, this is the first time I've heard of a limiting mach number for the IV-P. My Chilton PFD shows any mach above .35 at the top of the airspeed tape. I've seen .44 in cruise at altitude. (I giggled like a little girl.) Now I'm a little concerned that the "hard" Mmo should be placarded so as not to exceed it in a cruise power (usual) descent. Barry Knotts N4XE, LIV-P, Conti TSIO-550 Frederick Moreno wrote: > > > When Brent Regan and I were racing his Lancair IV Denver to Oshkosh > (1996, 97 as I recall), the descent profile was Mach limited initially > starting at 27,000 feet using a hard limit of Mach 0.58. This was > chosen because the factory aircraft was test flown to Mach 0.6 and we > did not want to enter the unknown. This Mach number (I had to compute > it in those early days -- no Mach displays then) was held until the > IAS built to Vne (274 knots IAS) and this IAS was held to the bottom > of descent, all occurring at 90-100% power. The maximum cruise speed > at 27,000 was about 320 knots TAS (corrected for temperature and > compressibility effects) and Mach 0.52. As I recall, it only required > 200-300 feet per minute initial descent at the high power setting to > drive the Mach number up to 0.58, so the descent started out very > flat, and the built up as the air got thicker. I think we hit Vne at > about 12-14,000 feet and the maximum descent rate near the bottom of > descent was off scale on the VSI. It sounded quite different from > cruise and caused the hair on the back of the neck to stand up a bit > particularly since much of the descent was in IMC. > > > > Key point for you IVP guys: It does not take much nose down high > altitudes and high power settings to push you up to Mmo, the maximum > allowable Mach number. > > > > Y'all be careful out there. > > > > Fred > > > --------------060501060704070709020305 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit I haven't seen much on Mmo. In fact, this is the first time I've heard of a limiting mach number for the IV-P. My Chilton PFD shows any mach above .35 at the top of the airspeed tape. I've seen .44 in cruise at altitude. (I giggled like a little girl.) Now I'm a little concerned that the "hard" Mmo should be placarded so as not to exceed it in a cruise power (usual) descent.

Barry Knotts
N4XE, LIV-P, Conti TSIO-550

Frederick Moreno wrote:

When Brent Regan and I were racing his Lancair IV Denver to Oshkosh (1996, 97 as I recall), the descent profile was Mach limited initially starting at 27,000 feet using a hard limit of Mach 0.58. This was chosen because the factory aircraft was test flown to Mach 0.6 and we did not want to enter the unknown. This Mach number (I had to compute it in those early days – no Mach displays then) was held until the IAS built to Vne (274 knots IAS) and this IAS was held to the bottom of descent, all occurring at 90-100% power. The maximum cruise speed at 27,000 was about 320 knots TAS (corrected for temperature and compressibility effects) and Mach 0.52. As I recall, it only required 200-300 feet per minute initial descent at the high power setting to drive the Mach number up to 0.58, so the descent started out very flat, and the built up as the air got thicker. I think we hit Vne at about 12-14,000 feet and the maximum descent rate near the bottom of descent was off scale on the VSI. It sounded quite different from cruise and caused the hair on the back of the neck to stand up a bit particularly since much of the descent was in IMC.

Key point for you IVP guys: It does not take much nose down high altitudes and high power settings to push you up to Mmo, the maximum allowable Mach number.

Y’all be careful out there.

Fred

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