X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from sccrmhc14.comcast.net ([63.240.77.84] verified) by logan.com (CommuniGate Pro SMTP 5.1c.3) with ESMTP id 1339196 for flyrotary@lancaironline.net; Sat, 19 Aug 2006 20:35:39 -0400 Received-SPF: none receiver=logan.com; client-ip=63.240.77.84; envelope-from=wschertz@comcast.net Received: from 7n7z201 (c-24-7-194-231.hsd1.il.comcast.net[24.7.194.231]) by comcast.net (sccrmhc14) with SMTP id <2006082000342901400ghjoge>; Sun, 20 Aug 2006 00:34:29 +0000 Message-ID: <00ac01c6c3f0$790e1050$e7c20718@7n7z201> From: "Bill Schertz" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] First flight - Oil temp Date: Sat, 19 Aug 2006 19:35:01 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00A9_01C6C3C6.90073450" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 This is a multi-part message in MIME format. ------=_NextPart_000_00A9_01C6C3C6.90073450 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Al, One other suggestion to those made by yourself and Joe Hull is to use = the oil smear technique to get some idea of how the flow is going. paint = a stripe of oil along the wing before the oil cooler and after it on the = exit, go fly, and see where the oil runs. Might give you some ideas = about where the problem lies. Local builder uses this technique and it = is pretty effective. Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Joe Hull=20 To: Rotary motors in aircraft=20 Sent: Sunday, August 06, 2006 10:11 PM Subject: [FlyRotary] First flight - Oil temp It was bugging me that I couldn't remember the reference to the = reverse scoop - so here's the link - it was Dick Rutan: http://www.ez.org/cp47-p11.htm =20 Essentially put the reverse scoop on the top of the wing all the way = ahead of the oil cooler for best cooling. =20 Joe Hull Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)=20 Redmond (Seattle), Washington =20 -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Joe Hull Sent: Sunday, August 06, 2006 8:01 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: ***SPAM*** [FlyRotary] First flight - Oil = temp =20 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. 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. =20 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. =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 "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! =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 -------------------------------------------------------------------------= ----- 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'm awaiting for shots = from my friend who took hundreds (OK, only about 150) and will be = editing for a while J. =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" 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. =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" 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. =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 'energize' the boundary = layer, and see if that helps. =20 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. =20 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. =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_00A9_01C6C3C6.90073450 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Al,
One other suggestion to those made by = yourself and=20 Joe Hull is to use the oil smear technique to get some idea of how the = flow is=20 going. paint a stripe of oil along the wing before the oil cooler and = after it=20 on the exit, go fly, and see where the oil runs. Might give you some = ideas about=20 where the problem lies. Local builder uses this technique and it is = pretty=20 effective.
 
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From:=20 Joe Hull=20
Sent: Sunday, August 06, 2006 = 10:11=20 PM
Subject: [FlyRotary] First = flight - Oil=20 temp

It was = bugging me=20 that I couldn=92t remember the reference to the reverse scoop =96 so = here=92s the=20 link =96 it was Dick Rutan:

http://www.ez.org/cp47-p11.htm

 

Essentially = put the=20 reverse scoop on the top of the wing all the way ahead of the oil = cooler for=20 best cooling.

 

Joe = Hull

Cozy Mk-IV N31CZ (65 hrs - = Rotary 13B NA)=20

Redmond (Seattle), Washington

 

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Joe Hull
Sent: Sunday, August 06, 2006 = 8:01=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: = ***SPAM***=20 [FlyRotary] First flight - Oil temp

 

Al,

I=92m not = an=20 aerodynamicist and don=92t pretend to be one=85with that said=85I = think your heading=20 down the right path with either a larger bottom scoop or VG=92s.  = The=20 bottom opening is definitely in the boundary layer that far back past = the=20 strake. The real trick is determining where the VG=92s go =96 that=92s = more trial=20 and error than science I think.

 

Also, I = think it was=20 Dick Rutan and/or Mike Melville who reported greatly improved oil = cooling (the=20 original Long-EZ=92s had oil cooler in the wing root) by putting a = reverse scoop=20 about half way back from where you have yours =96 i.e. about half the = distance=20 of the oil cooler. I think Dick actually reported putting the reverse = scoop=20 just ahead of the oil cooler. I guess the pressure drop is not = immediately=20 behind the scoop as one would expect but rather a few inches beyond=20 it.

 

Any who, = the sure=20 fire solution is obviously to drop the bottom scoop down and catch = some of the=20 free stream. You might be able to experiment without messing up your=20 fiberglass and paint too much by creating a larger scoop that you can = =93glue=20 on=94 with RTV or something that extends the existing scoop forward = and down=20 another inch or so. Once you find the optimum opening size and = distance from=20 the wing bottom =96 then do the real fiberglass work and open up and = drop the=20 existing scoop. Yes, you=92d have to try to account for the fact that = you would=20 be forcing air through the original size opening =96 but if you get it = to cool=20 with a larger scoop and the original openings just think how well it = will work=20 when you open up the original holes!

 

Sorry for = the ramble.=20 Hope that gives you some ideas.

 

Joe = Hull

Cozy Mk-IV N31CZ (65 hrs - = Rotary 13B NA)=20

Redmond (Seattle), Washington

 

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Al Gietzen
Sent: Sunday, August 06, 2006 = 6:45=20 PM
To: = Rotary motors in aircraft
Subject: ***SPAM*** [FlyRotary] = First=20 flight - Oil temp

 

Thanks everyone for = the=20 congratulatory messages, and for the support that is always so = helpful. =20 No pics to post yet because my camera battery went dead after the = first three=20 shots, so I=92m awaiting for shots from my friend who took hundreds = (OK, only=20 about 150) and will be editing for a while J.

 

The principal issue of = the day=20 was the higher than comfortable oil temperature; most likely due to=20 insufficient air flow through the cooler.  For anyone who would = like to=20 think aerodynamics for awhile and give an opinion on the simplest and = best=20 approach to remedy; read on.

 

The custom cooler for = this 265=20 hp engine is large.  The core here is about 5 =BC=94 wide, 22=94 = long and 3 =BC=94=20 thick. It is located in the wing root of the Velocity, behind the = spar, with=20 inlet underneath and exit on the top.  Alan Shaw, who I believe = pioneered=20 this approach, found the location worked very well.  When I = discussed the=20 installation with him years ago, he opined that a scoop under the wing = was=20 probably not necessary because of a pressure differential between = bottom and=20 top surfaces.  Since then, my investigations of pressure = distributions,=20 and similar installations that aren=92t working so well, make me=20 wonder.

 

Photo 1 is a view = under the wing=20 showing the OC air intake, wheel well, and the big armpit scoop for = the=20 coolant radiator in the cowl.  The inlet opening is about 1 = 1/8=94 wide and=20 23=94 long.  There really isn=92t a scoop, just an opening with = an extended=20 airfoil shaped lip which extends about =BD=94 into the free = stream.  The idea=20 was to minimize drag, and assume a more negative pressure at the exit = would=20 produce the necessary flow.  Photo 2 shows a front view where you = see the=20 wheel well and the inlet =96 very little extension into the free = stream. =20 Analysis suggests that the turbulent boundary layer on a smooth = surface at the=20 inlet location could be about 5/8 =96 3/4=94 in=20 thick.

 

The air exit fairing = is shown in=20 photo 3; and is shaped as it is to maintain attached flow and cause = minimal=20 turbulence going aft.  The effective exit area is about 1.6 times = the=20 inlet area.  The thickness of the core suggests the need for = pretty good=20 pressure differential for adequate flow.

 

Here are some=20 options:

a)  For the first = flight=20 the landing gear was never retracted. Since the open wheel well = forward of the=20 inlet would likely cause significant turbulence; try another flight = with the=20 gear retracted to see if that improves the=20 results.

b)    = Place=20 some VGs forward of the inlet to =91energize=92 the boundary layer, = and see if=20 that helps.

 

c)    =20 Extend the =91lip=92 = of the inlet to=20 form a proper ram scoop, possible also with VGs forward to break up = the=20 boundary layer, and accept the slight increase in=20 drag.

 

d)    = Do=20 something at the exit ( local =91expert=92 suggests there may be flow = separation=20 before the aft end of the fairing causing high pressure behind the=20 exit).  Put VGs on the top of the exit fairing and/or reduce exit = area.

 

e)    = None=20 of the above.

 

I suspect the normal = aerodynamic=20 pressure differential between the inlet and outlet points is minimal;=20 especially in level flight where it could be near zero.  Option = c) seems=20 the most sure-fire to me.

Thanks for=20 input.

 

Al

 

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