X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) X-Junk-Score: 0 [] X-KAS-Score: 0 [] From: "Marc Wiese cardmarc@charter.net" Received: from [47.43.20.28] (HELO impout004.msg.chrl.nc.charter.net) by logan.com (CommuniGate Pro SMTP 6.3.5) with ESMTPS id 127734 for flyrotary@lancaironline.net; Sat, 03 Jul 2021 13:44:18 -0400 Received-SPF: pass receiver=logan.com; client-ip=47.43.20.28; envelope-from=cardmarc@charter.net Received: from smtpclient.apple ([97.94.202.172]) by cmsmtp with ESMTPA id zjgOlb9XQNcdszjgOlvRHW; Sat, 03 Jul 2021 17:44:01 +0000 Authentication-Results: charter.net; none X-Authority-Analysis: v=2.4 cv=Pfg6Ogtd c=1 sm=1 tr=0 ts=60e0a1e1 a=xycr6CVXJRVtFs4WRGOeRA==:117 a=xycr6CVXJRVtFs4WRGOeRA==:17 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=o1OHuDzbAAAA:8 a=_6GpL_ENAAAA:8 a=J9I7UuOxB2FuOLJyoewA:9 a=QEXdDO2ut3YA:10 a=NyzhGB5-X0PB_ZczeW8A:9 a=IcLrPIOuWHRXlT0y:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=5YQ6H4ZxyGn-KoBYtt8s:22 Content-Type: multipart/alternative; boundary=Apple-Mail-9F7C47A2-9AA7-4428-A4B7-38FCE9CD59B4 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) Date: Sat, 3 Jul 2021 12:44:00 -0500 Message-Id: <08D76B00-5E5A-480F-A656-B65DD95919CF@charter.net> References: In-Reply-To: Subject: Re: [FlyRotary] Re: Cooling Inlets To: Rotary motors in aircraft X-Mailer: iPad Mail (18F72) X-CMAE-Envelope: MS4xfIUQaEJV7yb+2QKtOWR3BEXDc1XJCu4eYIYwn9Und1Wiqk7fp89dFQ32yrSpAPVydRnYP4yTLlhDih3L0PtqaE1+tt0VHGCm9WWxNvydnFayDnQBUryN Up5Yd+oiK4BdcZ7gH1Ya5to+464fWV0sDqTH7vva6DMgXlV+7lKyduCLympnZ7OCsdgvZxn3n89xCJYn5CEARaezAl18F2UVL6o= --Apple-Mail-9F7C47A2-9AA7-4428-A4B7-38FCE9CD59B4 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Anybody got pictures of these =E2=80=98optimized=E2=80=99 inlets? Are they r= ound? Which profile inlets? How shaped? Dimensions, please? M Sent from my iPad > On Jul 3, 2021, at 11:52 AM, Charlie England ceengland7@gmail.com wrote: > =EF=BB=BF > Hey, Tracy; welcome back! > Do you have Elon to thank for that, or did someone put a cell tower in the= middle of nowhere? >=20 > Charlie >=20 > On Sat, Jul 3, 2021 at 10:26 AM Tracy rwstracy@gmail.com wrote: >> That matches my experiences in RL Charlie. >>=20 >> Internet is working for the first time here in the off grid shack in CO. >>=20 >>=20 >> On Sat, Jul 3, 2021, 7:54 AM Charlie England ceengland7@gmail.com wrote: >>> Hi Finn, >>>=20 >>> I was hoping someone with better memory/understanding would jump in, but= I'll take a swing at 'general principles'.=20 >>>=20 >>> If memory serves, the guys who have applied the paper to hardware recent= ly have said something like this: >>> The sharper edged lips are the most efficient shape where the flow is 'p= erfect' into the diffuser, and there's no spillage over the outside of the l= ip. But in our typical situation we need lots of flow at low airspeed (climb= profile; high power) and less flow (relative to freestream) at high airspee= d (cruise). If airspeed is high enough that some of the air in front of the= inlet can't get in and must divert around the lip, the sharp edge of the li= p will cause turbulence and drag on the outside of the airframe (at high air= speed, where it hurts the most). So, we can't truly optimize the lip. If a c= owl flap will be used to increase cooling flow at low airspeed and reduce it= at high airspeed, that means there will be significant spillage around the l= ip at high airspeed. So while the fatter lip is less efficient in the ideal f= low situation, it ends up being better in the real world, because we must be= able to cool at low speed and we want minimum drag at high speed.=20 >>>=20 >>> There's also the 'internal vs external diffusion' issue. I think Bernie K= err was the 1st person that talked to me about that. Internal (K&W duct, for= instance) is theoretically more efficient, and could use a sharp edged lip,= but it's really difficult for us 'measure with a micrometer; cut with an ax= ' builders to get perfect. So the safer thing is to go big on the inlet to e= nsure plenty of flow, and then throttle the outlet to match actual flow to c= onditions, with a cowl flap. Since we'll have a lot of spillage around the i= nlet with the flap closed, that means a fat lip on the inlet to minimize dra= g when there's lots of spillage. >>>=20 >>> Or I could have an advanced case of oldtimer's, and I'm remembering it w= rong. >>> I hope someone will correct me if that's the case. >>>=20 >>> Charlie >>>=20 >>> On Wed, Jun 30, 2021 at 10:18 PM Finn Lassen finn.lassen@verizon.net wrote: >>>> Thanks. I guess I kept missing it because I don't understand what I'm l= ooking at. >>>> Can anyone help me understand the following and show me the optimum ins= ide/outside radius ratio (which I assume is one of the A-10 to A-40 contours= ): >>>> >>>>=20 >>>> >>>>=20 >>>> Finn >>>>=20 >>>> On 6/30/2021 9:45 PM, Charlie England ceengland7@gmail.com wrote: >>>>> Seems likely; I don't recall seeing a CR3485 referenced anywhere, eith= er. >>>>>=20 >>>>> On 6/30/2021 4:42 PM, Finn Lassen finn.lassen@verizon.net wrote: >>>>>> I tried in vain to find NASA_CR3485 (well, I found a NASA contractors= report on animal studies). >>>>>>=20 >>>>>> I wonder of he meant 3405? >>>>>> >>>>>>=20 >>>>>>=20 >>>>>> Anyone found a better match? >>>>>>=20 >>>>>> Finn >>>>>>=20 >>>>>> On 4/28/2011 9:07 AM, Tracy wrote: >>>>>>> Finally got around to finishing my cooling inlets. (pictures attache= d)=C3=AF=C2=BF=C2=BD Up until now they were simply round pipes sticking out o= f the cowl.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD The pipes are still there bu= t they have properly shaped bellmouths on them.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF= =C2=BD The shape and contours were derived from a NASA contractor report (NA= SA_CR3485) that you can find via Google.=C3=AF=C2=BF=C2=BD Lots of math & fo= rmulas in it but I just copied the best performing inlet picture of the cont= our.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD Apparently there is an optimum radi= us for the inner and outer lip of the inlet.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2= =BD There was no change to the inlet diameters of 5.25" on water cooler and 4= .75" on oil cooler. >>>>>>>=20 >>>>>>> The simple pipes performed adequately in level flight at moderate cr= uise settings even on hot days but oil temps would quickly hit redline at hi= gh power level flight and in climb.=C3=AF=C2=BF=C2=BD=20 >>>>>>>=20 >>>>>>> The significant change with the new inlet shape is that they appear t= o capture off-axis air flow=C3=AF=C2=BF=C2=BD (like in climb and swirling fl= ow=C3=AF=C2=BF=C2=BD induced by prop at high power)=C3=AF=C2=BF=C2=BD MUCH b= etter than the simple pipes. =C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD First flig= ht test was on a 94 deg. F day and I could not get the oil temp above 200 de= grees in a max power climb. =C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD They may ha= ve gone higher if the air temperature remained constant but at 3500 fpm the r= apidly decreasing OAT kept the temps well under redline (210 deg F). >>>>>>>=20 >>>>>>> I have an air pressure instrument reading the pressure in front of t= he oil cooler and was amazed at the pressure recovered from the prop wash.=C3= =AF=C2=BF=C2=BD At 130 MPH the pressure would almost double when the throttl= e was advanced to WOT. =C3=AF=C2=BF=C2=BD That did not happen nearly as much= with the simple pipes.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD=20 >>>>>>>=20 >>>>>>> These inlets ROCK! >>>>>>>=20 >>>>>>> Tracy Crook >>>>>>=20 >>>>>>=20 >>>>>> Virus-free. www.avast.com --Apple-Mail-9F7C47A2-9AA7-4428-A4B7-38FCE9CD59B4 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Anybody got pictures of these= =E2=80=98optimized=E2=80=99 inlets? Are they round? Which profile inlets? H= ow shaped? Dimensions, please?
M

Sent from my iP= ad

On Jul 3, 2021, at 11= :52 AM, Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net= > wrote:

=EF=BB=BF
Hey, Tracy; welcome back!
Do you have Elon to thank for that, or did someone put a c= ell tower in the middle of nowhere?

Charlie

On Sat, Jul 3, 2021 at 10:26 AM Tracy rwstracy@gmail.com <flyrotary@lancaironline.net> wrote:
That matche= s my experiences in RL Charlie.

Internet is working for the first time here in the off grid shack in CO.

= On Sat, Jul 3, 2021, 7:54 AM Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net= > wrote:
Hi Finn,

I was hoping someone with be= tter memory/understanding would jump in, but I'll take a swing at 'general p= rinciples'. 

If memory= serves, the guys who have applied the paper to hardware recently have said s= omething like this:
The sharper edged lips are the most efficient shape where the flow is 'p= erfect' into the diffuser, and there's no spillage over the outside of the l= ip. But in our typical situation we need lots of flow at low airspeed (climb= profile; high power) and less flow (relative to freestream) at high airspee= d (cruise). If  airspeed is high enough that some of the air in front o= f the inlet can't get in and must divert around the lip, the sharp edge of t= he lip will cause turbulence and drag on the outside of the airframe (at hig= h airspeed, where it hurts the most).  So, we can't truly optimize the l= ip. If a cowl flap will be used to increase cooling flow at low airspeed and= reduce it at high airspeed, that means there will be significant spillage a= round the lip at high airspeed. So while the fatter lip is less efficient in= the ideal flow situation, it ends up being better in the real world, becaus= e we must be able to cool at low speed and we want minimum drag at high spee= d. 

There's also the '= internal vs external diffusion' issue. I think Bernie Kerr was the 1st perso= n that talked to me about that. Internal (K&W duct, for instance) is the= oretically more efficient, and could use a sharp edged lip, but it's really d= ifficult for us 'measure with a micrometer; cut with an ax' builders to get p= erfect. So the safer thing is to go big on the inlet to ensure plenty of flo= w, and then throttle the outlet to match actual flow to conditions, with a c= owl flap. Since we'll have a lot of spillage around the inlet with the flap c= losed, that means a fat lip on the inlet to minimize drag when there's lots o= f spillage.

=
Or I could have= an advanced case of oldtimer's, and I'm remembering it wrong.
I hope someone will correct m= e if that's the case.

Charl= ie

On Wed, Jun 30, 2021 at 10:18 PM Finn Lassen finn.lassen@verizon.= net <flyrotary@lancaironline.net> wrote:
=20 =20 =20
Thanks. I guess I kept missing it because I don't understand what I'm looking at.
Can anyone help me understand the following and show me the optimum inside/outside radius ratio (which I assume is one of the A-10 to A-40 contours):
<nadfchpfafimnegl.png>

<kbdejbnihmgdehea.png>

Finn

On 6/30/2021 9:45 PM, Charlie England ceengland7@gmail.com wrote:=
=20
Seems likely; I don't recall seeing a CR3485 referenced anywhere, either.

On 6/30/2021 4:42 PM, Finn Lassen finn.lassen@verizon.net wrote:
=20
I tried in vain to find = NASA_CR3485 (well, I found a NASA contractors report on animal studies).

I wonder of he meant 3405?
<bnmfmdnlndmefidc.png>


Anyone found a better match?

Finn

On 4/28/2011 9:07 AM, Tracy wrote:
=20 Finall= y got around to finishing my cooling inlets. (pictures attached)=C3=AF=C2=BF=C2=BD Up until now they were simply ro= und pipes sticking out of the cowl.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD= The pipes are still there but they have properly shaped bellmouths on them.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD The shape and cont= ours were derived from a NASA contractor report (NASA_CR3485) that you can find via Google.=C3=AF=C2=BF=C2=BD Lots of math & formulas in= it but I just copied the best performing inlet picture of the contour.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD Apparently ther= e is an optimum radius for the inner and outer lip of the inlet.=C3=AF=C2=BF=C2=BD=C3=AF= =C2=BF=C2=BD There was no change to the inlet diameters of 5.25" on water cooler and 4.75" on oil cooler.

The simple pipes performed adequately in level flight at moderate cruise settings even on hot days but oil temps would quickly hit redline at high power level flight and in climb.=C3=AF=C2=BF=C2=BD

The significant change with the new inlet shape is that they appear to capture off-axis air flow=C3=AF=C2=BF=C2=BD (= like in climb and swirling flow=C3=AF=C2=BF=C2=BD induced by prop at= high power)=C3=AF=C2=BF=C2=BD MUCH better than the simple pipes. =C3= =AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD First flight test was on a 94 deg. F day and I could not get the oil temp above 200 degrees in a max power climb. =C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD They may have gone high= er if the air temperature remained constant but at 3500 fpm the rapidly decreasing OAT kept the temps well under redline (210 deg F).

I have an air pressure instrument reading the pressure in front of the oil cooler and was amazed at the pressure recovered from the prop wash.=C3=AF=C2=BF=C2=BD At 1= 30 MPH the pressure would almost double when the throttle was advanced to WOT. =C3=AF=C2=BF=C2=BD That did not happen near= ly as much with the simple pipes.=C3=AF=C2=BF=C2=BD=C3=AF=C2=BF=C2=BD <= br>
These inlets ROCK!

Tracy Crook



3D"" Vi= rus-free. www.avast.com


= --Apple-Mail-9F7C47A2-9AA7-4428-A4B7-38FCE9CD59B4--