X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 04 Apr 2010 18:37:12 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTP id 4195130 for lml@lancaironline.net; Sun, 04 Apr 2010 11:50:10 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.124; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=3DUlJUu7qWFNpNttJVwyA1nQS84iC7EN/BDLX6qJweI= c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=b0jkCgG7AAAA:8 a=CjxXgO3LAAAA:8 a=Ia-xEzejAAAA:8 a=gKLyQ0ufAAAA:8 a=-QidQ3XyAAAA:8 a=UAH1NcSDT7ool9m4J8sA:9 a=AyzwR43OpGL3ycFS8uYA:7 a=7rTktH1ESvZTR4idAuUTqdbTc4sA:4 a=wPNLvfGTeEIA:10 a=BF2xWdBC1hcA:10 a=rC2wZJ5BpNYA:10 a=EzXvWhQp4_cA:10 a=A0LnVcZjDxIA:10 a=RdxCudR78EbT7oIy:21 a=msoWyheRNsj-JaSX:21 a=ubrd0QTLAAAA:8 a=b1pTE5v5XMCTC3mr0Q0A:9 a=yfMmLfC6C_grMFQlT18A:7 a=tNmLeHeKPORu-h0dvhQqXSx_tYUA:4 a=DttEQBt-ZXMA:10 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1397] helo=Lobo) by hrndva-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 9C/37-28179-E05B8BB4; Sun, 04 Apr 2010 15:49:34 +0000 X-Original-Message-ID: <001001cad40e$681110e0$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] IV-P AC X-Original-Date: Sun, 4 Apr 2010 11:49:26 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01CAD3EC.E0BA5190" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_000D_01CAD3EC.E0BA5190 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The "Meredith effect" is what I couldn't think of earlier. -------------------------------------------------------------------------= ------- Has anybody looked at the potential similarity to the air scoop on the = P-51 ? Most people believe the P-51 achieved it's speed due to the "new" = laminar airfoil. Subsequent testing has shown that's not the case. The = advantage was the major reduction of typical cooling drag as implemented = in the P-51 lower air scoop. The design of the scoop along with the = expanding air within absorbing the excess engine heat did the trick. http://www.pprune.org/aviation-history-nostalgia/387708-napier-heston-bel= ly-scoop-first-one.html Wolfgang From: Charlie Kohler =20 Sender: =20 Subject: Re: [LML] IV-P AC=20 Date: Sat, 03 Apr 2010 20:03:41 -0400=20 To: lml@lancaironline.net=20 =20 =20 =20 Hi Bob, It would be interesting to note whether your AC is the early = version/or late. The difference is the dimension that the scoop extends = down from the fuselage. I don't recall the exact figures but the next = time you're at the airplane with a rule--- get the measurement from the = center of the fuselage down to the top of the scoop. This will tell me = whether or not you will gain anything from the conversion. The later = models with the scoop tucked up close to the fuselage had very little = drag. At any rate-- if you do intend to make this change-- do a test = flight before you start and get some indicated airspeed runs at various = altitudes. Make sure the engine power figures are recorded also.=20 Then we can have definitive data to support this long-standing = debate. After I installed mine, I compared that data from a prop test I = had done a year earlier for MT propeller--testing the three Blade versus = the four blade. And compared that data with the AC data at the same = altitudes in power settings. There is always some scatter but I found = that 3 kn was the average penalty.=20 And--what you will be able to establish that I was not-- how much = does the condenser cooling exhaust causes drag. As you can imagine if = this exhaust air is strong enough you will have to trim the airplane = nose up (causing drag). Also, very exhausting at 90=B0 to the flow of = air over the skin, will cause drag. How much we don't know. At any rate it will be a very interesting test. Thanks =20 Charlie K. See me on the web at=20 www.Lancair-IV.com -------------------------------------------------------------------------= - From: Bob Rickard To: lml@lancaironline.net Sent: Fri, April 2, 2010 2:06:28 PM Subject: [LML] IV-P AC IV-P Experts: I am contemplating replacing my air conditioning unit in my IV-P = from the under fuselage scoop to one that is installed in the tail. = Purely for speed benefits. My unit works fine but I hear that it may = slow me down by 10-20 or more knots. What are your recommendations? = Is there already a thread on this? I have the room in the tail, CG = shouldn't be an issue, but I want to know the bad news. I have the = airplane in Phoenix part of the time (yep, it's really hot, and the = current AC is adequate) and I need the system to work at least a little = on the ground so I don't die before takeoff - this is my major concern. = And I would love to hear if some of you have actually made this change = and if so what speed benefit you have observed. Lastly, is there more = than one vendor option? Thanks for your comments Bob Rickard IV-P ( I didn't build it!) =20 ------=_NextPart_000_000D_01CAD3EC.E0BA5190 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The "Meredith=20 effect" is what I couldn't think of earlier.
 

Has anybody looked at the potential = similarity to=20 the air scoop on the P-51 ? Most people believe the P-51 achieved it's = speed due=20 to the "new" laminar airfoil. Subsequent testing has shown that's not = the case.=20 The advantage was the major reduction of typical cooling drag as = implemented in=20 the P-51 lower air scoop. The design of the scoop along with the = expanding air=20 within absorbing the excess engine heat did the trick.
 
http://www.pprune.org/aviation-history-n= ostalgia/387708-napier-heston-belly-scoop-first-one.html
=
 = ;
Wolfgang
 

lml@lancaironline.net
From: Charlie Kohler=20 <charliekohler@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] IV-P AC
Date: Sat, 03 Apr 2010 20:03:41 = -0400
To:


 

Hi Bob,

It would be interesting to note whether your AC is the early = version/or=20 late. The difference is the dimension that the scoop extends down = from the=20 fuselage. I don't recall the exact figures but the next time = you're at the=20 airplane with a rule--- get the measurement from the center of the = fuselage down to the top of the scoop. This will tell me whether = or not=20 you will gain anything from the conversion. The later models with = the=20 scoop tucked up close to the fuselage had very little drag.

At any rate-- if you do intend to make this change-- do a test = flight=20 before you start and get some indicated airspeed runs at various=20 altitudes. Make sure the engine power figures are recorded also. =

Then we can have definitive data to support this=20 long-standing debate.

 

After I installed mine, I compared that data from a prop test I = had=20 done a year earlier for MT propeller--testing the three Blade = versus the=20 four blade. And compared that data with the AC data at the same = altitudes=20 in power settings. There is always some scatter but I found that 3 = kn was=20 the average penalty.

And--what you will be able to establish that I was not-- how = much does=20 the condenser cooling exhaust causes drag. As you can imagine if = this=20 exhaust air is strong enough you will have to trim the airplane = nose up=20 (causing drag). Also, very exhausting at 90=B0 to the flow of air = over the=20 skin, will cause drag. How much we don't know.

At any rate it will be a very interesting test.

 Thanks


 
Charlie K.
 
See me on the web at
 


From: Bob Rickard=20 <r.rickard@rcginc-us.com>
To:=20 lml@lancaironline.net
Sent: Fri, April 2, = 2010=20 2:06:28 PM
Subject: [LML] IV-P = AC

IV-P Experts:

 

I am contemplating replacing my air = conditioning=20 unit in my IV-P from the under fuselage scoop to one that is = installed in=20 the tail.  Purely for speed benefits.  My unit works = fine but I=20 hear that it may slow me down by 10-20 or more knots.   = What are=20 your recommendations?  Is there already a thread on = this?  I=20 have the room in the tail, CG shouldn=92t be an issue, but I want = to know=20 the bad news.  I have the airplane in Phoenix part of the = time (yep,=20 it=92s really hot, and the current AC is adequate) and I need the = system to=20 work at least a little on the ground so I don=92t die before = takeoff =96 this=20 is my major concern.  And I would love to hear if some of you = have=20 actually made this change and if so what speed benefit you have=20 observed.  Lastly, is there more than one vendor = option?

 

Thanks for your comments

 

Bob Rickard

IV-P ( I didn=92t build=20 = it!)

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