X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wr-out-0506.google.com ([64.233.184.232] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2187257 for flyrotary@lancaironline.net; Thu, 19 Jul 2007 11:12:54 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.184.232; envelope-from=rwstracy@gmail.com Received: by wr-out-0506.google.com with SMTP id i30so503709wra for ; Thu, 19 Jul 2007 08:12:16 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=YifW+fl2wQ/CcQOWap3QXVjLDY4vc7OzMWwNBdRBWn91N8cSW3SbYbgziF0Moik6unhEbpwTKKge0VA40ojU47RB2Vpj/3Thf2Pm1YBw3D3rAT8Qy3YbaCrrcFQ7vVzLOilOUWTQctf5cZ0eiTVauDCQXkToRhmtLvx/BSNagVs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=ubBDm0eTyuiNHLjv2gwIbAWvmKjne/S5TbgsUgdi1w+MEN0AH8P+CtzVH6JhbaOflnUBfeH1zgdublcrJnKpSKfBCxHcSi8jwz0+WP3kPshWA+VjysCbCkVYj6iYOHgkVWr/IoimucHda94As8ZUSumTWAkgJlwtFK1qyvX4EL4= Received: by 10.143.6.1 with SMTP id j1mr217239wfi.1184857935181; Thu, 19 Jul 2007 08:12:15 -0700 (PDT) Received: by 10.143.37.17 with HTTP; Thu, 19 Jul 2007 08:12:15 -0700 (PDT) Message-ID: <1b4b137c0707190812v985286fi24fefa5f8719cb50@mail.gmail.com> Date: Thu, 19 Jul 2007 11:12:15 -0400 From: "Tracy Crook" Sender: rwstracy@gmail.com To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Oil cooler inlet In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_130139_18435954.1184857935132" References: X-Google-Sender-Auth: 8fb123f5cabe4910 ------=_Part_130139_18435954.1184857935132 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Al, I haven't had time to read the whole thread so you've probably heard this already. My main observation is the boundary layer problem. I seriously underestimated the effect it has on some aux scoops since it was not critical (avionics cooling) and was amazed at how big a deal it was. The small pressure inside the cockpit was enough to stop all airflow. I ended up turning the scoop 180 degrees (facing backwards) and using the positive pressure in front of the canopy (not a solution for you but just an illustration of how boundary layer effects scoops). The 'flair' of the diffuser is almost always under-done. When done properly, it just looks wrong. When it is working right, the static pressure is pretty close to theoretica= l for the airspeed of the aircraft. Don't stop working on it till you're there (or until cooling is OK). My right side cooling scoop is pretty terrible (only ~ 50% of theoretical dynamic pressure recovery) since I spli= t it between a rad and oil cooler. The Left side works great & gives me 105= % of theoretical (prop blast doing the magic part). The negative pressure above the wing is a relatively feeble thing (as you have already discovered) so that was a dead end. Tracy On 7/19/07, Steve Brooks wrote: > > Gentlemen, > I've been following this thread with great interest, as I would still lik= e > to make further improvements to my cooling. > Since Ernest lives close by to me, I may see if he can look at my > radiators to get his thoughts on improvements. > > Steve Brooks > > -----Original Message----- > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]*On > Behalf Of *Ed Anderson > *Sent:* Wednesday, July 18, 2007 3:17 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Oil cooler inlet > > I agree with Ernest (even if he clearly must be completely and totally > wrong {:>)), difficult to find any rule of thumb parameters for a vane. > > I have marked the region (red color) in you duct that I think is most > critical in helping the slower moving boundary layer turn and to > prevent/minimize its effect on the rest of the air flow. Once you have > helped the boundary layer accelerate and get around the curve, then I > believe the vane has done about all it can. I would start out the vane > approx 1/2 the depth of your opening in order to try and capture some of = the > higher velocity air outside the boundary layer. I would then compress tha= t > air toward the roof of the duct by reducing the distance between vane and > top of duct in order to increase its velocity. > > Depending on how fancy you want to make the vane, I though that perhaps > adding slots so the higher velocity air in the lower part of the duct cou= ld > help the boundary flow make the turn and further energize it. > > Don't have a clue as to how much this well help, but I do believe it will > help some. > > Ed > > ----- Original Message ----- > *From:* Al Gietzen > *To:* Rotary motors in aircraft > *Sent:* Wednesday, July 18, 2007 2:15 PM > *Subject:* [FlyRotary] Oil cooler inlet > > > > Attached is a more accurate drawing of the oil cooler inlet x-section; > with a few pressure measurements. Based on temps, the average flow > velocity into the scoop is about 85 fps (57 mph) =96 all at about 160 mph > airplane speed. (Point "A" is really about 4-5" ahead of the scoop.) > > > > Ernest; since you were first to propose the internal airflow, or vane; > what would you think is the appropriate shape, position, etc. I can > understand your non-participation on the 'other' list after being labeled > "completely and totally wrong". (That's what you get for not reading his > bookJ). > > > > Others ideas obliviously of interest as well =96 ED? > > > > Al > > ------------------------------ > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > ------=_Part_130139_18435954.1184857935132 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Al, I haven't had time to read the whole thread so you've= probably heard this already.
 
My main observation is the boundary layer problem.  I seriously u= nderestimated the effect it has on some aux scoops since it was not critica= l (avionics cooling) and was amazed at how big a deal it was.  Th= e small pressure inside the cockpit was enough to stop all airflow.  I= ended up turning the scoop 180 degrees (facing backwards) and using the po= sitive pressure in front of the canopy (not a solution for you but just an = illustration of how boundary layer effects scoops). =20
 
The 'flair' of the diffuser is almost always under-done. = When done properly, it just looks wrong. 
When it is working right, the static pressure is pretty close to = theoretical for the airspeed of the aircraft.  Don't stop working = on it till you're there (or until cooling is OK).  My right side c= ooling scoop is pretty terrible (only ~ 50% of theoretical dynamic pressure= recovery) since I split it between a rad and oil cooler.   The L= eft side works great & gives me 105% of theoretical (prop blast doing t= he magic part). =20
 
 The negative pressure above the wing is a relatively feeble thin= g (as you have already discovered) so that was a dead end.
 
Tracy

 
On 7/19/07, = Steve Brooks <cozy4pilot@gma= il.com> wrote:
Gentlemen,
I've been = following this thread with great interest, as I would still like to make fu= rther improvements to my cooling.
Since Ernest l= ives close by to me, I may see if he can look at my radiators to get his th= oughts on improvements.
=  
Steve Brooks
-----Origi= nal Message-----
From: Rotary motors in aircraft [mailto: flyrotary@lancaironline.net]On Behalf Of Ed Anderson
Sent:= Wednesday, July 18, 2007 3:17 PM
To: Rotary motors in aircra= ft
Subject: [FlyRotary] Re: Oil cooler inlet
I agree with Ernest (even if he clearly must be c= ompletely and totally wrong {:>)), difficult to find any rule of thumb p= arameters for a vane. 
 
 I have marked the region (red color)  = in you duct that I think is most critical in helping the slower moving boun= dary layer turn and to prevent/minimize its effect on the rest of the air f= low.  Once you have helped the boundary layer accelerate and get aroun= d the curve, then I believe the vane has done about all it can.  I wou= ld start out the vane approx 1/2 the depth of your opening in order to try = and capture some of the higher velocity air outside the boundary layer. I w= ould then compress that air toward the roof of the duct by reducing the dis= tance between vane and top of duct in order to increase its velocity. = =20
 
Depending on how fancy you want to make the vane,= I though that perhaps adding slots so the higher velocity air in the lower= part of the duct could help the boundary flow make the turn and further en= ergize it.=20
 
Don't have a clue as to how much this well he= lp, but I do believe it will help some.
 
Ed 
----- Original Message -----
From: Al Gietzen <= /div>
Sent: Wednesday, July 18, 2007 2:15 = PM
Subject: [FlyRotary] Oil cooler inle= t

 

Attached is a more accurate drawing of the oil cooler inlet= x-section; with a few pressure measurements.  Based on temps, the average flow velocity into the sc= oop is about 85 fps (57 mph) =96 all at about 160 mph airplane speed. (Poin= t "A" is really about 4-5" ahead of the scoop.)

 

Ernest; since you were first to propose the internal airflo= w, or vane; what would you think is the appropriate shape, position, etc. &= nbsp;I can understand your non-participation on the 'other' list after bein= g labeled "completely and totally wrong". (That's what you get for not read= ing his book J).

 

Others ideas obliviously of interest as well =96 ED?=

 

Al

--
Homepage:  http://w= ww.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html


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