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 elasmtp-curtail.atl.sa.earthlink.net ([209.86.89.64] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTP id 4194710 for lml@lancaironline.net; Sat, 03 Apr 2010 20:11:12 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.64; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=cYvcHWVaTSMO/BzqmISAAsnnWgE5bSXPKHufRsN4tVyK7tEI9fOntKuYQcdIRcnL; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.178] (helo=ccaselt3) by elasmtp-curtail.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1NyDQ3-0002h7-Mi for lml@lancaironline.net; Sat, 03 Apr 2010 20:10:27 -0400 X-Original-Message-ID: <122CC7532C084CE4BD64711E647D90E6@nvidia.com> From: "Colyn Case at earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: IV-P AC X-Original-Date: Sat, 3 Apr 2010 20:10:01 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_12D2_01CAD369.A42B5310" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940cac5bee60390e0b4bd2b089a7950bb81350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.178 This is a multi-part message in MIME format. ------=_NextPart_000_12D2_01CAD369.A42B5310 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Charlie, that's interesting information. =20 Are you willing to publish your absolute numbers? Personally I don't really care about the condenser exhaust issue. =20 Colyn ----- Original Message -----=20 From: Charlie Kohler=20 To: lml@lancaironline.net=20 Sent: Saturday, April 03, 2010 8:03 PM Subject: [LML] Re: IV-P AC 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=C2=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=E2=80=99t be an issue, but I want to know the bad news. I have = the airplane in Phoenix part of the time (yep, it=E2=80=99s 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=E2=80=99t die before takeoff =E2=80=93 = 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=E2=80=99t build it!) ------=_NextPart_000_12D2_01CAD369.A42B5310 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Charlie, that's interesting=20 information.  
Are you willing to publish your absolute=20 numbers?
Personally I don't really care about = the condenser=20 exhaust  issue.  
 
Colyn
 
----- Original Message -----
From:=20 Charlie=20 Kohler
Sent: Saturday, April 03, 2010 = 8:03=20 PM
Subject: [LML] Re: IV-P = AC

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=20 down to the top of the scoop. This will tell me whether or not you = will gain=20 anything from the conversion. The later models with the scoop tucked = up close=20 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 = altitudes.=20 Make sure the engine power figures are recorded also.

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

 

After I installed mine, I compared that data from a prop test I had = done a=20 year earlier for MT propeller--testing the three Blade versus the four = blade.=20 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=20 the average penalty.

And--what you will be able to establish that I was not-- how much = does the=20 condenser cooling exhaust causes drag. As you can imagine if this = exhaust air=20 is strong enough you will have to trim the airplane nose up (causing = drag).=20 Also, very exhausting at 90=C2=B0 to the flow of air over the skin, = will cause=20 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: = lml@lancaironline.net
Sent: Fri, April 2, 2010 = 2:06:28=20 PM
Subject: [LML] = IV-P=20 AC

IV-P=20 Experts:

 

I = am=20 contemplating replacing my air conditioning unit in my IV-P from the = under=20 fuselage scoop to one that is installed in the tail.  Purely for = speed=20 benefits.  My unit works fine but I hear that it may slow me down = by=20 10-20 or more knots.   What are your recommendations?  = Is there=20 already a thread on this?  I have the room in the tail, CG = shouldn=E2=80=99t be=20 an issue, but I want to know the bad news.  I have the airplane = in=20 Phoenix part of the time (yep, it=E2=80=99s really hot, and the = current AC is=20 adequate) and I need the system to work at least a little on the = ground so I=20 don=E2=80=99t die before takeoff =E2=80=93 this is my major = concern.  And I would love to=20 hear if some of you have actually made this change and if so what = speed=20 benefit you have observed.  Lastly, is there more than one vendor = option?

 

Thanks for=20 your comments

 

Bob=20 Rickard

IV-P ( I=20 didn=E2=80=99t build = it!)

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