X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 31 Jan 2010 23:58:12 -0500 Message-ID: X-Original-Return-Path: Received: from blu0-omc3-s6.blu0.hotmail.com ([65.55.116.81] verified) by logan.com (CommuniGate Pro SMTP 5.3.2) with ESMTP id 4106007 for lml@lancaironline.net; Sun, 31 Jan 2010 16:01:46 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.55.116.81; envelope-from=bill_kennedy_3@hotmail.com Received: from BLU0-SMTP55 ([65.55.116.74]) by blu0-omc3-s6.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Sun, 31 Jan 2010 13:01:09 -0800 X-Originating-IP: [166.137.6.155] X-Originating-Email: [bill_kennedy_3@hotmail.com] X-Original-Message-ID: X-Original-Return-Path: bill_kennedy_3@hotmail.com Received: from [10.213.197.217] ([166.137.6.155]) by BLU0-SMTP55.blu0.hotmail.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Sun, 31 Jan 2010 13:00:59 -0800 From: Bill Kennedy X-Original-To: Lancair Mailing List In-Reply-To: Content-Type: multipart/alternative; boundary=Apple-Mail-1-1049120065 Content-Transfer-Encoding: 7bit X-Mailer: iPhone Mail (7D11) Mime-Version: 1.0 (iPhone Mail 7D11) Subject: Re: [LML] Re: Engine out gear down Issue/The procedure! This was a wake up call for me.. X-Original-Date: Sun, 31 Jan 2010 13:00:44 -0800 References: X-OriginalArrivalTime: 31 Jan 2010 21:01:08.0096 (UTC) FILETIME=[8285A800:01CAA2B8] --Apple-Mail-1-1049120065 Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Math is nice but if you don't practice this stuff you're probably going to die if you have an engine failure. Also, this stuff about needing 120kias to round out in a Lancair is dead wrong as is the notion of lowering your gear at the last minute. What is hpat teaching? Sent from my iPhone On Jan 31, 2010, at 6:57, Gary Casey wrote: > I ran through some numbers regarding Michael's comments below. > Starting with the sailplane comment, he says that slowing from > 135kts to 65 in a zoom can result in a gain of 800 feet. If all the > energy were converted to altitude(no drag) the gain would be 1,276 > ft, so a gain of 800 ft seems reasonable for a very low-drag > airframe - 2/3 of the energy can be converted to altitude. In the > case mentioned of 120 kts to 75 kts the number comes out to a gain > of 765 ft. How much of that is eaten up by drag? Certainly > compared to the sailplane, a lot. Would the altitude gain be half? > I doubt it. 1/4? Maybe, so as a guess you could count on perhaps a > 200 ft altitude gain. How much do you need to flare? Depends on > the descent rate. I calculated it based on 2,000 ft/min - arresting > that is equivalent to an altitude gain of 34.5 ft, much lower than > the 200 ft mentioned above. It would be good if someone measured > the actual no-power descent rate with gear and flaps down. > > In summary, the math suggests that a no-power approach speed of 120 > kts should leave more than enough energy to flare. How much more? > I'll bet not a lot, but still more. I don't have an answer to the > question, but this is how the numbers work out. I have done a full- > flap no-power descent with my ES (gear down, of course :-) at 105 > kts and the descent rate was over 2,000 ft/min with a frighteningly > high negative deck angle. Flaring from that condition would be > interesting, to say the least. My conclusion is that Randy's > warning is well founded. > > I would, perhaps, disagree with the admonition that retracting flaps > when on final will result in a guaranteed disaster. Certainly any > change in configuration at the last second creates a high work load, > but at least in my airplane, the difference in behavior between 20 > degrees and 40 degrees of flaps is 90% drag. So, if one were to > think he was high for the landing, added full flaps and then > discovered he was now low, I see no problem with then retracting the > flaps to 10 or 20 degrees. Assuming the speed were high (120?) the > flaps could even be retracted all the way without problem except for > the pitch change required. And then dropping the flaps during the > flare is a good way to arrest the descent. I'm a little reluctant > to post this last paragraph as I have no credentials (no military > fighter jet experience, no instructor rating, no multi-engine jet > time, and no stays in Holiday Inn Express) except for a modest > understanding of the engineering principles involved. > > Gary > > From: Michael Newman > Subject: [LML] Re: Engine out gear down Issue/The procedure! This > was a wake up call for me... > To: lml@lancaironline.net > Date: Wednesday, January 27, 2010, 4:52 PM > > I am a LOBO instructor. I own and fly a Lancair IV-P. > I am also a sailplane instructor. > > This discussion reminds me of one in the sailplane community talking > about deploying full spoilers and being able to flare properly. It > was thoroughly debunked there as it should be here. > > The issue is carrying enough energy in the form of airspeed to > arrest the rate of descent without going below the stall speed. > > There is no question in my mind that the IV-P with gear down, flaps > down, engine stopped and spoilers fully extended can carry enough > energy to arrest the rate of descent (flare). 120 knots will be more > than enough. I have landed my IV-P with full spoilers, gear and > flaps down. 95 knots is plenty of airspeed to arrest the descent in > this configuration with the engine as pulled back as I can get it. > I doubt a truly dead engine will add as much more drag as the full > spoilers. > > Gliding at 120 knots with a stall speed is in the range of 75 knots > is a differential of 45 knots. This is enough to climb a few hundred > feet much less arrest the rate of descent. Work out the physics and > you can see how much altitude you gain for converting this much > horizontal speed to vertical speed. In sailplanes we expect about > an 800 foot altitude gain in a pull up from 135 knots to 60 knots. > Possibly a surprise to people here is that a Lancair will not be > much different. It is energy conversion not drag that matters. > --Apple-Mail-1-1049120065 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Math is nice but if you don't = practice this stuff you're probably going to die if you have an engine = failure. Also, this stuff about needing 120kias to round out in a = Lancair is dead wrong as is the notion of lowering your gear at the last = minute. What is hpat teaching?

Sent from my = iPhone

On Jan 31, 2010, at 6:57, Gary Casey <casey.gary@yahoo.com> = wrote:

I ran through some numbers regarding = Michael's comments below.  Starting with the sailplane comment, he = says that slowing from 135kts to 65 in a zoom can result in a gain of = 800 feet.  If all the energy were converted to altitude(no drag) = the gain would be 1,276 ft, so a gain of 800 ft seems reasonable for a = very low-drag airframe - 2/3 of the energy can be converted to altitude. =  In the case mentioned of 120 kts to 75 kts the number comes out to = a gain of 765 ft.  How much of that is eaten up by drag? =  Certainly compared to the sailplane, a lot.  Would the = altitude gain be half?  I doubt it.  1/4?  Maybe, so as a = guess you could count on perhaps a 200 ft altitude gain.  How much = do you need to flare?  Depends on the descent rate.  I calculated it based on 2,000 ft/min - arresting that is = equivalent to an altitude gain of 34.5 ft, much lower than the 200 ft = mentioned above.  It would be good if someone measured the actual = no-power descent rate with gear and flaps = down.

In summary, the math suggests that a = no-power approach speed of 120 kts should leave more than enough energy = to flare.  How much more?  I'll bet not a lot, but still more. =  I don't have an answer to the question, but this is how the = numbers work out.  I have done a full-flap no-power descent with my = ES (gear down, of course :-) at 105 kts and the descent rate was over = 2,000 ft/min with a frighteningly high negative deck angle. =  Flaring from that condition would be interesting, to say the = least.  My conclusion is that Randy's warning is well = founded.

I would, perhaps, disagree with the = admonition that retracting flaps when on final will result in a guaranteed disaster.  Certainly any change = in configuration at the last second creates a high work load, but at = least in my airplane, the difference in behavior between 20 degrees and = 40 degrees of flaps is 90% drag.  So, if one were to think he was = high for the landing, added full flaps and then discovered he was now = low, I see no problem with then retracting the flaps to 10 or 20 = degrees.  Assuming the speed were high (120?) the flaps could even = be retracted all the way without problem except for the pitch change = required.  And then dropping the flaps during the flare is a good = way to arrest the descent.  I'm a little reluctant to post this = last paragraph as I have no credentials (no military fighter jet = experience, no instructor rating, no multi-engine jet time, and no stays = in Holiday Inn Express) except for a modest understanding of the = engineering principles involved.

Gary

From: Michael Newman <mnewman@dragonnorth.com>Subject: [LML] Re: Engine out gear down Issue/The procedure! This was a = wake up call for me...
To: lml@lancaironline.net
Dat= e: Wednesday, January 27, 2010, 4:52 PM

I am = a LOBO instructor. I own and fly a Lancair IV-P.

I am also a sailplane = instructor.

 

This = discussion reminds me of one in the sailplane community talking about = deploying full spoilers and being able to flare properly. It was = thoroughly debunked there as it should be here.

 

The issue is carrying enough energy in the form of = airspeed to arrest the rate of descent without going below the stall = speed.

 

 


= --Apple-Mail-1-1049120065--