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From: Bulent Aliev <atlasyts@bellsouth.net>
Subject: Re: [FlyRotary] Re: First flight - Oil temp
Date: Sun, 6 Aug 2006 23:47:59 -0400
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>


David, I don't have the measurements with me, but I can get them in =20
the morning. About temporary adhesive, If it was me I would use =20
mechanical fasteners, rivets with washer back ups etc. Would not =20
count on any glue or silicone. If this piece comes loose, in a pusher =20=

will go in the prop. Silicone may leave residue that will make it =20
hard to remove for later painting? Just rivet the sucker and put some =20=

5 min epoxy-micro filler in the gaps. (I'm thinking glass aircraft =20
here). Holes are very eazy to fill later.

On Aug 6, 2006, at 11:33 PM, David Carter wrote:

> I agree with Bulent about bottom scoop needing to hang down more =20
> (think P-51) and  Bob White & Richard (refine the exit "profile").  =20=

> Make your underwing inlet hang down 4-5 inches, at least.
>
> Bulent, how far below your fuselage is the lower edge of your inlet =20=

> (lower face of bottom of inlet, i.e., inside face, not lower =20
> outside contour)  I looks like top inner face of your inlet is 3 =20
> inches below fuselage and another 7 inches down to the lower inner =20
> face.
>
> If RTV adhesive works, that would be fine.  If more strength was =20
> needed (later on at higher speeds) could anyone recommend a glue =20
> for  "temporary scoops" that might be stronger but soften for =20
> removal/modification with hair dryer heat, e.g., 130 degrees, just =20
> below the 140 deg or whatever that the fiberglass structure of the =20
> wing would be affected?
>
> David Carter
> ----- Original Message -----
> From: Joe Hull
> To: Rotary motors in aircraft
> Sent: Sunday, August 06, 2006 9:11 PM
> Subject: [FlyRotary] First flight - Oil temp
>
> It was bugging me that I couldn=92t remember the reference to the =20
> reverse scoop =96 so here=92s the link =96 it was Dick Rutan:
>
> http://www.ez.org/cp47-p11.htm
>
>
>
> Essentially put the reverse scoop on the top of the wing all the =20
> way ahead of the oil cooler for best cooling.
>
>
>
> Joe Hull
>
> Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)
>
> Redmond (Seattle), Washington
>
>
>
> From: Rotary motors in aircraft =20
> [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 =20
> temp
>
>
>
> Al,
>
> I=92m not an aerodynamicist and don=92t pretend to be one=85with that =20=

> said=85I think your heading down the right path with either a larger =20=

> bottom scoop or VG=92s.  The bottom opening is definitely in the =20
> boundary layer that far back past the strake. The real trick is =20
> determining where the VG=92s go =96 that=92s more trial and error than =
=20
> science I think.
>
>
>
> Also, I think it was Dick Rutan and/or Mike Melville who reported =20
> greatly improved oil cooling (the original Long-EZ=92s had oil cooler =20=

> in the wing root) by putting a reverse scoop about half way back =20
> from where you have yours =96 i.e. about half the distance of the oil =20=

> cooler. I think Dick actually reported putting the reverse scoop =20
> just ahead of the oil cooler. I guess the pressure drop is not =20
> immediately behind the scoop as one would expect but rather a few =20
> inches beyond it.
>
>
>
> Any who, the sure fire solution is obviously to drop the bottom =20
> scoop down and catch some of the free stream. You might be able to =20
> experiment without messing up your fiberglass and paint too much by =20=

> creating a larger scoop that you can =93glue on=94 with RTV or =20
> something that extends the existing scoop forward and down another =20
> inch or so. Once you find the optimum opening size and distance =20
> from the wing bottom =96 then do the real fiberglass work and open up =20=

> and drop the existing scoop. Yes, you=92d have to try to account for =20=

> the fact that you would be forcing air through the original size =20
> opening =96 but if you get it to cool with a larger scoop and the =20
> original openings just think how well it will work when you open up =20=

> 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 =20
> [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 =20
> support that is always so helpful.  No pics to post yet because my =20
> camera battery went dead after the first three shots, so I=92m =20
> awaiting for shots from my friend who took hundreds (OK, only about =20=

> 150) and will be editing for a while J.
>
>
>
> The principal issue of the day was the higher than comfortable oil =20
> temperature; most likely due to insufficient air flow through the =20
> cooler.  For anyone who would like to think aerodynamics for awhile =20=

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

> that aren=92t working so well, make me wonder.
>
>
>
> Photo 1 is a view under the wing showing the OC air intake, wheel =20
> well, and the big armpit scoop for the coolant radiator in the =20
> cowl.  The inlet opening is about 1 1/8=94 wide and 23=94 long.  There =
=20
> really isn=92t a scoop, just an opening with an extended airfoil =20
> 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 =20
> exit would produce the necessary flow.  Photo 2 shows a front view =20
> where you see the wheel well and the inlet =96 very little extension =20=

> into the free stream.  Analysis suggests that the turbulent =20
> boundary layer on a smooth surface at the inlet location could be =20
> about 5/8 =96 3/4=94 in thick.
>
>
>
> The air exit fairing is shown in photo 3; and is shaped as it is to =20=

> maintain attached flow and cause minimal turbulence going aft.  The =20=

> effective exit area is about 1.6 times the inlet area.  The =20
> thickness of the core suggests the need for pretty good pressure =20
> differential for adequate flow.
>
>
>
> Here are some options:
>
> a)  For the first flight the landing gear was never retracted. =20
> Since the open wheel well forward of the inlet would likely cause =20
> significant turbulence; try another flight with the gear retracted =20
> to see if that improves the results.
>
> b)    Place some VGs forward of the inlet to =91energize=92 the =20
> boundary layer, and see if that helps.
>
>
>
> c)     Extend the =91lip=92 of the inlet to form a proper ram scoop, =20=

> possible also with VGs forward to break up the boundary layer, and =20
> accept the slight increase in drag.
>
>
>
> d)    Do something at the exit ( local =91expert=92 suggests there may =
=20
> be flow separation before the aft end of the fairing causing high =20
> pressure behind the exit).  Put VGs on the top of the exit fairing =20
> and/or reduce exit area.
>
>
>
> e)    None of the above.
>
>
>
> I suspect the normal aerodynamic pressure differential between the =20
> inlet and outlet points is minimal; especially in level flight =20
> where it could be near zero.  Option c) seems the most sure-fire to =20=

> me.
>
> Thanks for input.
>
>
>
> Al
>
>
>
>