X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from eastrmmtao106.cox.net ([68.230.240.48] verified) by logan.com (CommuniGate Pro SMTP 5.3c4) with ESMTP id 4036744 for flyrotary@lancaironline.net; Wed, 23 Dec 2009 12:43:33 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.240.48; envelope-from=tmann@n200lz.com Received: from eastrmimpo02.cox.net ([68.1.16.120]) by eastrmmtao106.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20091223174258.ULRN1916.eastrmmtao106.cox.net@eastrmimpo02.cox.net> for ; Wed, 23 Dec 2009 12:42:58 -0500 Received: from testPC ([98.168.254.7]) by eastrmimpo02.cox.net with bizsmtp id Lhix1d00H0ALyG202hixrb; Wed, 23 Dec 2009 12:42:58 -0500 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=463f1N2YpqHLOamhbp4wF7Njg/30QkdnTZ27hYvsP6Y= c=1 sm=1 a=u3n+HnEbI1wdzZeyJY7NnA==:17 a=UuQ-GN1u-IPdAM5GFgcA:9 a=Sy21h9yklxZWnUKGUQMA:7 a=T2SaosXXIcT05wws6ZUPvsmjrMwA:4 a=MlCIT-dn5qhdm4PK:21 a=R_9ZDvq0McBOvWgp:21 a=yMhMjlubAAAA:8 a=SSmOFEACAAAA:8 a=6eFPGYCExx8457K6Ef4A:9 a=swtpmqYQyWS7uxurRLwA:7 a=3HCdCOrskHJkdVKGmS5VwlQfn4QA:4 a=u3n+HnEbI1wdzZeyJY7NnA==:117 X-CM-Score: 0.00 From: "Thomas Mann" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Air Flow Question Date: Wed, 23 Dec 2009 11:43:07 -0600 Message-ID: <006801ca83f7$638ee3b0$2aacab10$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0069_01CA83C5.18F473B0" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcqD696uOkF50JIZTsW1dyxGiQxfdwAA8Meg Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_0069_01CA83C5.18F473B0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Of course. Being a pusher driver, I think of inlet speeds in terms of the speed of the airplane. So does the fact that the inlet is behind the prop give a much higher effective velocity? Al, I'm in the same boat (i.e. pusher configuration.) As far as inlet speed, For my application it going to be pretty close to my airspeed. For you tractor types, the inlet speed will be higher due to the prop-blast. As a former skydiver and jump master, I can attest to the physical effects of prop blast as one climbs out the open door of an aircraft to experience it first hand. When you see the facial skin flapping on a 25 year old, you know there is some additional airspeed at work there. Prior to reading the links Ed sent me, I was thinking a straight flare was going to take care of the diffuser layout. After researching these sources and digging into some NACA papers from WWII, it becomes obvious that the same considerations need to be applied to the diffuser as one would apply to the wing airfoil to maintain laminar flow and avoid separation and the associated turbulence in order to obtain the greatest benefit from the least amount of drag. As far as I can tell, thrust recovery in the P-51 is legend. Never found anything in the way of proof that it really occurred. The P-51 scoop is not a deviation into some new theory for my airplane. Instead, it was the plans method. ..and yes, the 'Meredith Effect' is a reality. (F. W. Meredith 1935) Reference also: "Spitfire - The History" by Morgan & Shacklady. Page 25 The exhaust from the P-51 scoop is travelling at a higher speed than the inlet so from what I've read, that equates to thrust. I'm not trying to build a ram-jet. The idea is to capitalize as much as possible of the heat energy to cancel out the drag created by the scoop. My research here is not a case of 'the paralysis of analysis.' I spend a lot of time working on my project 'Physically'. I also spend a lot of time 'thinking' about the upcoming phases so in effect while I'm sitting through one of those boring presentations at work (that don't involve me in the least) I'm mentally crunching numbers, airfoils and the like. ..in the meantime, I believe I have a radiator core face dimension to work with. I'm looking at some airfoil shapes that I have available to me to determine if there is a possibility of using one of those for the profile of my diffuser. What the hell ... I'm going to be snowed in again within the next few hours (once this freezing rain turns to snow and the winds kick up to 50+) soI should be able to get something done while I'm waiting for the epoxy to cure. Al ... you said it best. Merry Christmas to all and a Happy New Year to boot! T Mann ------=_NextPart_000_0069_01CA83C5.18F473B0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

Of course. Being a pusher driver, I think of = inlet speeds in terms of the speed of the airplane. So does the fact that the = inlet is behind the prop give a much higher effective = velocity?

 

 Al,

 I’m in the same boat (i.e. pusher = configuration.)

 

As far as inlet speed, For my application it going to be = pretty close to my airspeed. For you tractor types, the inlet speed will be = higher due to the prop-blast. As a former skydiver and jump master, I can attest to = the physical effects of prop blast as one climbs out the open door of an = aircraft to experience it first hand. When you see the facial skin flapping on a = 25 year old, you know there is some additional airspeed at work = there.

 

Prior to reading the links Ed sent me, I was thinking a = straight flare was going to take care of the diffuser layout. After researching = these sources and digging into some NACA papers from WWII, it becomes obvious = that the same considerations need to be applied to the diffuser as one would = apply to the wing airfoil to maintain laminar flow and avoid separation and = the associated turbulence in order to obtain the greatest benefit from the = least amount of drag.

 

As far as I can tell, thrust recovery in the = P-51 is legend. Never found anything in the way of proof that it really = occurred.

The P-51 scoop is not a deviation into some new theory = for my airplane. Instead, it was the plans method.

 

……and yes, the ‘Meredith Effect’ = is a reality. (F. W. Meredith 1935)

Reference also: "Spitfire - The History" = by Morgan & Shacklady. Page 25

The exhaust from the P-51 scoop is travelling at a higher = speed than the inlet so from what I’ve read, that equates to thrust. = I’m not trying to build a ram-jet. The idea is to capitalize as much as = possible of the heat energy to cancel out the drag created by the scoop. =

 

My research here is not a case of ‘the paralysis of analysis.’ I spend a lot of time working on my project = ‘Physically’. I also spend a lot of time ‘thinking’ about the upcoming = phases so in effect while I’m sitting through one of those boring = presentations at work (that don’t involve me in the least) I’m mentally = crunching numbers, airfoils and the like.

 

….in the meantime, I believe I have a radiator core = face dimension to work with. I’m looking at some airfoil shapes that I = have available to me to determine if there is a possibility of using one of = those for the profile of my diffuser.

 

What the hell ……. I’m going to be = snowed in again within the next few hours (once this freezing rain turns to snow = and the winds kick up to 50+) soI should be able to get something done while = I’m waiting for the epoxy to cure.

 

Al ….. you said it best. Merry Christmas to all and = a Happy New Year to boot!

 

T Mann

 

 

 

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