X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [216.211.128.10] (HELO mail-in03.adhost.com) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1311314 for flyrotary@lancaironline.net; Sun, 06 Aug 2006 23:01:55 -0400 Received-SPF: none receiver=logan.com; client-ip=216.211.128.10; envelope-from=joeh@pilgrimtech.com Received: from Pilgrim10 (c-67-183-14-47.hsd1.wa.comcast.net [67.183.14.47]) by mail-in03.adhost.com (Postfix) with ESMTP id 966432ACC8D for ; Sun, 6 Aug 2006 20:02:22 -0700 (PDT) (envelope-from joeh@pilgrimtech.com) From: "Joe Hull" To: "'Rotary motors in aircraft'" Subject: RE: ***SPAM*** [FlyRotary] First flight - Oil temp Date: Sun, 6 Aug 2006 20:00:44 -0700 Message-ID: <00ac01c6b9cd$b6c84410$bb02a8c0@redmond.corp.microsoft.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00AD_01C6B993.0B4721E0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: Aca5w0EvTY7/f3xdSVuvt+vxGaco1AABldIw X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_00AD_01C6B993.0B4721E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Al, I=92m not an aerodynamicist and don=92t pretend to be one=85with that = said=85I think your heading down the right path with either a larger bottom scoop or = VG=92s. The bottom opening is definitely in the boundary layer that far back = past the strake. The real trick is determining where the VG=92s go =96 = that=92s more trial and error than science I think. =20 Also, I think it was Dick Rutan and/or Mike Melville who reported = greatly improved oil cooling (the original Long-EZ=92s had oil cooler in the = wing root) by putting a reverse scoop about half way back from where you have yours =96 i.e. about half the distance of the oil cooler. I think Dick actually reported putting the reverse scoop just ahead of the oil = cooler. I guess the pressure drop is not immediately behind the scoop as one would expect but rather a few inches beyond it. =20 Any who, the sure fire solution is obviously to drop the bottom scoop = down and catch some of the free stream. You might be able to experiment = without messing up your fiberglass and paint too much by creating a larger scoop that you can =93glue on=94 with RTV or something that extends the = existing scoop forward and down another inch or so. Once you find the optimum opening = size and distance from the wing bottom =96 then do the real fiberglass work = and open up and drop the existing scoop. Yes, you=92d have to try to account = for the fact that you would be forcing air through the original size opening = =96 but if you get it to cool with a larger scoop and the original openings = just think how well it will work when you open up the original holes! =20 Sorry for the ramble. Hope that gives you some ideas. =20 Joe Hull Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)=20 Redmond (Seattle), Washington =20 _____ =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen Sent: Sunday, August 06, 2006 6:45 PM To: Rotary motors in aircraft Subject: ***SPAM*** [FlyRotary] First flight - Oil temp =20 Thanks everyone for the congratulatory messages, and for the support = that is always so helpful. No pics to post yet because my camera battery went = dead after the first three shots, so I=92m awaiting for shots from my friend = who took hundreds (OK, only about 150) and will be editing for a while :-). =20 The principal issue of the day was the higher than comfortable oil temperature; most likely due to insufficient air flow through the = cooler. For anyone who would like to think aerodynamics for awhile and give an opinion on the simplest and best approach to remedy; read on. =20 The custom cooler for this 265 hp engine is large. The core here is = about 5 =BC=94 wide, 22=94 long and 3 =BC=94 thick. It is located in the wing = root of the Velocity, behind the spar, with inlet underneath and exit on the top. = Alan Shaw, who I believe pioneered this approach, found the location worked = very well. When I discussed the installation with him years ago, he opined = that a scoop under the wing was probably not necessary because of a pressure differential between bottom and top surfaces. Since then, my = investigations of pressure distributions, and similar installations that aren=92t = working so well, make me wonder. =20 Photo 1 is a view under the wing showing the OC air intake, wheel well, = and the big armpit scoop for the coolant radiator in the cowl. The inlet opening is about 1 1/8=94 wide and 23=94 long. There really isn=92t a = scoop, just an opening with an extended airfoil shaped lip which extends about = =BD=94 into the free stream. The idea was to minimize drag, and assume a more = negative pressure at the exit would produce the necessary flow. Photo 2 shows a front view where you see the wheel well and the inlet =96 very little extension into the free stream. Analysis suggests that the turbulent boundary layer on a smooth surface at the inlet location could be about = 5/8 =96 3/4=94 in thick. =20 The air exit fairing is shown in photo 3; and is shaped as it is to = maintain attached flow and cause minimal turbulence going aft. The effective = exit area is about 1.6 times the inlet area. The thickness of the core = suggests the need for pretty good pressure differential for adequate flow. =20 Here are some options: a) For the first flight the landing gear was never retracted. Since the open wheel well forward of the inlet would likely cause significant turbulence; try another flight with the gear retracted to see if that improves the results. b) Place some VGs forward of the inlet to =91energize=92 the boundary = layer, and see if that helps. =20 c) Extend the =91lip=92 of the inlet to form a proper ram scoop, = possible also with VGs forward to break up the boundary layer, and accept the = slight increase in drag. =20 d) Do something at the exit ( local =91expert=92 suggests there may = be flow separation before the aft end of the fairing causing high pressure = behind the exit). Put VGs on the top of the exit fairing and/or reduce exit = area. =20 e) None of the above. =20 I suspect the normal aerodynamic pressure differential between the inlet = and outlet points is minimal; especially in level flight where it could be = near zero. Option c) seems the most sure-fire to me. Thanks for input. =20 Al =20 ------=_NextPart_000_00AD_01C6B993.0B4721E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Al,

I’m not an aerodynamicist and = don’t pretend to be one…with that said…I think your heading down = the right path with either a larger bottom scoop or VG’s.=A0 The = bottom opening is definitely in the boundary layer that far back past the strake. The = real trick is determining where the VG’s go – that’s more = trial and error than science I think.

 

Also, I think it was Dick Rutan = and/or Mike Melville who reported greatly improved oil cooling (the original = Long-EZ’s had oil cooler in the wing root) by putting a reverse scoop about half = way back from where you have yours – i.e. about half the distance of the = oil cooler. I think Dick actually reported putting the reverse scoop just = ahead of the oil cooler. I guess the pressure drop is not immediately behind the = scoop as one would expect but rather a few inches beyond = it.

 

Any who, the sure fire solution is obviously to drop the bottom scoop down and catch some of the free = stream. You might be able to experiment without messing up your fiberglass and paint = too much by creating a larger scoop that you can “glue on” with = RTV or something that extends the existing scoop forward and down another inch = or so. Once you find the optimum opening size and distance from the wing bottom = – then do the real fiberglass work and open up and drop the existing = scoop. Yes, you’d have to try to account for the fact that you would be = forcing air through the original size opening – but if you get it to cool with = a larger scoop and the original openings just think how well it will work = when you open up the original holes!

 

Sorry for the ramble. Hope that = gives you some ideas.

 

Joe = Hull

Cozy Mk-IV N31CZ (65 hrs - Rotary = 13B NA)

Redmond (Seattle), Washington

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Sunday, August 06, = 2006 6:45 PM
To: Rotary motors in aircraft
Subject: ***SPAM*** = [FlyRotary] First flight - Oil temp

 

Thanks everyone for the congratulatory messages, = and for the support that is always so helpful.  No pics to post yet because = my camera battery went dead after the first three shots, so I’m = awaiting for shots from my friend who took hundreds (OK, only about 150) and will be = editing for a while J.=

 

The principal issue of the day was the higher than comfortable oil temperature; most likely due to insufficient air flow = through the cooler.  For anyone who would like to think aerodynamics for = awhile and give an opinion on the simplest and best approach to remedy; read = on.

 

The custom cooler for this 265 hp engine is large.  The core here is about 5 =BC” wide, 22” long and 3 = =BC” thick. It is located in the wing root of the Velocity, behind the spar, = with inlet underneath and exit on the top.  Alan Shaw, who I believe = pioneered this approach, found the location worked very well.  When I = discussed the installation with him years ago, he opined that a scoop under the wing = was probably not necessary because of a pressure differential between bottom = and top surfaces.  Since then, my investigations of pressure = distributions, and similar installations that aren’t working so well, make me = wonder.

 

Photo 1 is a view under the wing showing the OC air intake, wheel well, and the big armpit scoop for the coolant radiator in = the cowl.  The inlet opening is about 1 1/8” wide and 23” = long.  There really isn’t a scoop, just an opening with an extended airfoil shaped lip which extends about =BD” into the free = stream.  The idea was to minimize drag, and assume a more negative pressure at the = exit would produce the necessary flow.  Photo 2 shows a front view where = you see the wheel well and the inlet – very little extension into the = free stream.  Analysis suggests that the turbulent boundary layer on a = smooth surface at the inlet location could be about 5/8 – 3/4” in = thick.

 

The air exit fairing is shown in photo 3; and is = shaped as it is to maintain attached flow and cause minimal turbulence going aft.  The effective exit area is about 1.6 times the inlet area.  = The thickness of the core suggests the need for pretty good pressure = differential for adequate flow.

 

Here are some options:

a)  For the first = flight the landing gear was never retracted. Since the open wheel well forward of = the inlet would likely cause significant turbulence; try another flight with = the gear retracted to see if that improves the = results.

b)    = Place some VGs forward of the inlet to ‘energize’ the boundary = layer, and see if that helps.

 

c)     = Extend the ‘lip’ of the inlet to form a proper ram scoop, possible also = with VGs forward to break up the boundary layer, and accept the slight = increase in drag.

 

d)    = Do something at the exit ( local ‘expert’ suggests there may be = flow separation before the aft end of the fairing causing high pressure = behind the exit).  Put VGs on the top of the exit fairing and/or reduce exit = area.

 

e)    = None of the above.

 

I suspect the normal aerodynamic pressure = differential between the inlet and outlet points is minimal; especially in level = flight where it could be near zero.  Option c) seems the most sure-fire to = me.

Thanks for input.

 

Al

 

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