X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 19 Jun 2011 19:56:11 -0400 Message-ID: X-Original-Return-Path: Received: from vms173009pub.verizon.net ([206.46.173.9] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with ESMTP id 5025333 for lml@lancaironline.net; Sun, 19 Jun 2011 12:45:44 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.173.9; envelope-from=n5zq@verizon.net Received: from p6520y ([unknown] [173.72.167.62]) by vms173009.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0LN100JI6QJ901G0@vms173009.mailsrvcs.net> for lml@lancaironline.net; Sun, 19 Jun 2011 11:45:11 -0500 (CDT) X-Original-Message-id: <8AE070AA995545DEA4452794922FA323@p6520y> From: "Bill Harrelson" X-Original-To: "Lancair Mailing List" References: In-reply-to: Subject: Re: [LML] Re: And how about a full feathering prop? X-Original-Date: Sun, 19 Jun 2011 12:45:18 -0400 MIME-version: 1.0 Content-type: multipart/alternative; boundary="----=_NextPart_000_00DB_01CC2E7E.BEBB3A80" X-Priority: 3 X-MSMail-priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3508.1109 X-MIMEOLE: Produced By Microsoft MimeOLE V15.4.3508.1109 This is a multi-part message in MIME format. ------=_NextPart_000_00DB_01CC2E7E.BEBB3A80 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Robert, Unless you have some kind of catastrophic failure which causes the = engine to seize, the prop will not stop rotating even at speeds far = below best glide speed. I have attempted, and failed, to stop the prop = in flight with the mixture in cut off. There should never be a need to = =E2=80=9Ccrank=E2=80=9D the engine in flight to get a re-start in a IV, = nor would there be a lack of oil pressure (unless the failure was oil = related in which case you=E2=80=99re probably dealing with a seizure = anyway). =20 Your comment about the testing being done with the engine running is, of = course, correct. There is a difference between gliding with a simulated = failure (engine at idle) and a truly dead engine...but that difference = is fairly small. I have tested this in a 320 as well a IV and found only = 1-200 fpm difference. Even with the engine actually failed the IV is an = excellent glider when in clean configuration and the prop control full = aft. The MT prop will govern to a lower RPM than a Hartzell so the MT = equipped craft will do a bit better in the glide, all else being equal. = Even with the Hartzell prop a IV is capable of producing a glide ratio = that is close to double what you would have in a Cessna 182, for = example. A full feathering prop will increase the glide ratio slightly, = but not significantly, at the cost of additional weight, complexity and = cost.=20 It is clearly an individual decision whether to equip your plane with a = feathering prop or not. Some of us have chosen the feathering prop, most = of us have gone with the non-feathering. I would suggest that proper = training in emergency procedures such as engine failure would increase = your survival chances in an engine out situation far, far more than a = feathering prop without such training.=20 Bill Harrelson N5ZQ 320 1,950 hrs N6ZQ IV under construction =20 From: RONALD STEVENS=20 Sent: Sunday, June 19, 2011 11:30 AM To: lml@lancaironline.net=20 Subject: [LML] Re: And how about a full feathering prop? Hi Robert Thanks for the explanation, and sure as hell I am going to try to see = the glide ratio as it has been debated many times by NON lancair owners = I know. Now for your explanation, I am thinking you are doing your test with a = running engine, but that is not when we are needing a full feather prop, = right? We need it when the mill dies on us, so no oil pressure so = therefore no way to feather in any kind of form, right?=20 (now I have been told by a Aerostar owner that they then just crank the = engine to get some low oil pressure and this way they feather, I am not = sure if this would work as I do not have this experience at all) But I do know that when the engine quiets, we try to restart it first by = switching the fuel selector, crank until we figured out that it won't = start and then=E2=80=A6=E2=80=A6well then it would be handy to have the = full feather prop, right? (or do I see this wrong and if so please tell = me, I am here to learn :) A glide ratio of 18:1 is fantastic, this is actually the same as the = Evolution, and if I am not mistaken, with the same glide speed :) From: Robert R Pastusek Reply-To: Lancair Mailing List Date: Sat, 18 Jun 2011 20:32:00 -0400 To: Subject: [LML] Re: And how about a full feathering prop? Ronald wrote: =20 For what I have gathered so far the lancair 4p has a glide ratio similar = like a piano LOL In other words if the engine quits then open the door, = throw out your keys because there is where you land LOL =20 Well, this might not be true, or is it?=20 =20 So how about the full feathering prop ? Does anyone have experience with = the before and after installation? How much they cost and data? =20 And I needed to respond to this=E2=80=A6 =20 My IV-P has a glide ratio (at 120 KIAS) of between 5:1 and 20:1, = depending on configuration. The difference is truly = amazing/impressive/sobering=E2=80=A6 depending on your situation and = mind set. With the gear and flaps down and the RPM at max (prop all the = way in), the glide ratio approximates that of a brick=E2=80=A6not = really, but you=E2=80=99re coming down so fast relative to forward = progress that it=E2=80=99s difficult to plan and execute a planned = touchdown (at least for me). With the gear and flaps up, AND THE PROP = CONTROL ALL THE WAY OUT, my glide ratio at gross weight is approximately = 18:1, increasing to a bit better than 20:1 at 800# under gross. At this = glide ratio, the performance and =E2=80=9Csight picture=E2=80=9D = approximates that of some gliders. It=E2=80=99s easy to plan and execute = an approach and landing to a pre-planned spot=E2=80=A6ideally a runway. = I have practiced this many times from various altitudes/distances from = the airport to a full stop on the runway, using the gear to increase my = descent rate, and then the flaps and/or the prop control to adjust the = touchdown point. Using the prop control is ideal because the drag = effect/descent rate increase almost immediately reversible by pushing it = back in. Not so with the flaps. One feature of my Chelton EFIS is a = wind-adjusted glide range predictor. I have tested this many times = starting at altitudes up to 17,500=E2=80=99 and (set at 18:1) gives me = a very accurate and immediate sight picture of airfields within glide = range. If it=E2=80=99s within the green circle, I can turn toward an = airfield and execute a safe landing there. My MT 4-blade is not full = feathering, but allows the engine to run at approximately 700 RPM when = at idle and the RPM set to min. I believe this is pretty close to 0 = thrust, as the engine idles at approximately 600 RPM on the ground.=20 =20 So, in summary, the throw out the keys and follow them down scenario can = be executed if you really want to go down, but a planned glide at 120 = KIAS (very close to best glide for my airplane) in clean configuration = yields approximately the performance of a 2-place sail plane=E2=80=94and = you have the ability to transition easily between these limits as = needed. Try it; you=E2=80=99ll be impressed. =20 Bob =20 PS: I considered and rejected a full feathering prop for what I have. = Wouldn=E2=80=99t trade for any amount of money=E2=80=A6 ------=_NextPart_000_00DB_01CC2E7E.BEBB3A80 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Robert,
 
Unless you have some kind of catastrophic failure which causes the = engine=20 to seize, the prop will not stop rotating even at speeds far below best = glide=20 speed. I have attempted, and failed, to stop the prop in flight with the = mixture=20 in cut off. There should never be a need to =E2=80=9Ccrank=E2=80=9D the = engine in flight to get=20 a re-start in a IV, nor would there be a lack of oil pressure (unless = the=20 failure was oil related in which case you=E2=80=99re probably dealing = with a seizure=20 anyway). 
 
Your comment about the testing being done with the engine running = is, of=20 course, correct. There is a difference between gliding with a simulated = failure=20 (engine at idle) and a truly dead engine...but that difference is fairly = small.=20 I have tested this in a 320 as well a IV and found only 1-200 fpm = difference.=20 Even with the engine actually failed the IV is an excellent glider when = in clean=20 configuration and the prop control full aft. The MT prop will govern to = a lower=20 RPM than a Hartzell so the MT equipped craft will do a bit better in the = glide,=20 all else being equal. Even with the Hartzell prop a IV is capable of = producing a=20 glide ratio that is close to double what you would have in a Cessna 182, = for=20 example. A full feathering prop will increase the glide ratio slightly, = but not=20 significantly, at the cost of additional weight, complexity and cost. =
 
It is clearly an individual decision whether to equip your plane = with a=20 feathering prop or not. Some of us have chosen the feathering prop, most = of us=20 have gone with the non-feathering. I would suggest that proper training = in=20 emergency procedures such as engine failure would increase your survival = chances=20 in an engine out situation far, far more than a feathering prop without = such=20 training.
 
Bill Harrelson
N5ZQ 320 1,950 hrs
N6ZQ  IV under construction
 
 
Sent: Sunday, June 19, 2011 11:30 AM
Subject: [LML] Re: And how about a full feathering=20 prop?
 
Hi Robert
 
Thanks for the explanation, and sure as hell I am going to try to = see the=20 glide ratio as it has been debated many times by NON lancair owners I=20 know.
 
Now for your explanation, I am thinking you are doing your test = with a=20 running engine, but that is not when we are needing a full feather prop, = right?=20 We need it when the mill dies on us, so no oil pressure so therefore no = way to=20 feather in any kind of form, right?
 
(now I have been told by a Aerostar owner that they then just crank = the=20 engine to get some low oil pressure and this way they feather, I am not = sure if=20 this would work as I do not have this experience at all)
 
But I do know that when the engine quiets, we try to restart it = first by=20 switching the fuel selector, crank until we figured out that it won't = start and=20 then=E2=80=A6=E2=80=A6well then it would be handy to have the full = feather prop, right? (or do I=20 see this wrong and if so please tell me, I am here to learn :)
 
A glide ratio of 18:1 is fantastic, this is actually the same as = the=20 Evolution, and if I am not mistaken, with the same glide speed :)
 
From: Robert R Pastusek <rpastusek@htii.com>
Reply-To: Lancair Mailing List <lml@lancaironline.net>
Date: Sat, 18 Jun 2011 20:32:00 = -0400
To: <lml@lancaironline.net>
Subject: [LML] Re: And how about a = full=20 feathering prop?
 

Ronald=20 wrote:

 

For=20 what I have gathered so far the lancair 4p has a glide ratio similar = like a=20 piano LOL In other words if the engine quits then open the door, throw = out your=20 keys because there is where you land LOL

 

Well,=20 this might not be true, or is it?

 

So how=20 about the full feathering prop ? Does anyone have experience with the = before and=20 after installation?  How much they cost and=20 data?

 

And=20 I needed to respond to this=E2=80=A6

 

My=20 IV-P has a glide ratio (at 120 KIAS) of between 5:1 and 20:1, depending = on=20 configuration. The difference is truly = amazing/impressive/sobering=E2=80=A6 depending on=20 your situation and mind set. With the gear and flaps down and the RPM at = max=20 (prop all the way in), the glide ratio approximates that of a = brick=E2=80=A6not really,=20 but you=E2=80=99re coming down so fast relative to forward progress that = it=E2=80=99s difficult=20 to plan and execute a planned touchdown (at least for me). With the gear = and=20 flaps up, AND THE PROP CONTROL ALL THE WAY OUT, my glide ratio at gross = weight=20 is approximately 18:1, increasing to a bit better than 20:1 at 800# = under gross.=20 At this glide ratio, the performance and =E2=80=9Csight picture=E2=80=9D = approximates that of=20 some gliders. It=E2=80=99s easy to plan and execute an approach and = landing to a=20 pre-planned spot=E2=80=A6ideally a runway. I have practiced this many = times from various=20 altitudes/distances from the airport to a full stop on the runway, using = the=20 gear to increase my descent rate, and then the flaps and/or the prop = control to=20 adjust the touchdown point. Using the prop control is ideal because the = drag=20 effect/descent rate increase almost immediately reversible by pushing it = back=20 in. Not so with the flaps.  = One=20 feature of my Chelton EFIS is a wind-adjusted glide range predictor. I = have=20 tested this many times starting at altitudes up to 17,500=E2=80=99 and =  (set at 18:1) gives me a very = accurate=20 and immediate sight picture of airfields within glide range. If = it=E2=80=99s within the=20 green circle, I can turn toward an airfield and execute a safe landing = there. My=20 MT 4-blade is not full feathering, but allows the engine to run at = approximately=20 700 RPM when at idle and the RPM set to min. I believe this is pretty = close to 0=20 thrust, as the engine idles at approximately 600 RPM on the ground.=20

 

So,=20 in summary, the throw out the keys and follow them down scenario can be = executed=20 if you really want to go down, but a planned glide at 120 KIAS (very = close to=20 best glide for my airplane) in clean configuration yields approximately = the=20 performance of a 2-place sail plane=E2=80=94and you have the ability to = transition=20 easily between these limits as needed. Try it; you=E2=80=99ll be  = impressed.

 

Bob

 

PS:=20 I considered and rejected a full feathering prop for what I have. = Wouldn=E2=80=99t  trade for any amount of=20 money=E2=80=A6

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