I’m not seeing a ratio either. This page has links to several NACA papers including CR 3405.

cz.net/Interesting_Technical_Reports/Technical_Papers.htm

Bobby

Page 104

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Monday, May 11, 2020 12:49 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotary Engine Noise

 

Take a look at page 304 Inlet Geometry.  Bobby

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Monday, May 11, 2020 12:34 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotary Engine Noise

 

Thank you Bobby.

No, I don't think it's in the NASA CR3405.

Of course it's possible it's there (or in one of the many other NACA and NASA papers I looked in) and I just don't see the tree for the forest.

According to Tracy, the paper gives the optimal number.

I did pull the profile from Tracy's cooling inlet mold and have that, and could measure the inside and outside radius on that and calculate the approximate number from that.

Finn

On 5/11/2020 9:32 AM, Bobby J. Hughes bhughes@qnsi.net wrote:

Finn,

 

Check your email. The attachment may be the document you are looking for.

 

Bobby

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Monday, May 11, 2020 8:06 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotary Engine Noise

 

Fairly sure that's not the one.

Does is it give the number for the ideal inside/outside radius ratio?

Finn

On 5/10/2020 10:42 PM, Andrew Martin andrew@martinag.com.au wrote:

Aerodynamics of Propulsion

Dietrich Kuchemann

Johanna Weber

1st Edition 1953.

 

I got a copy at reasonable price, it is a photocopy of an original, but cannot for the life of me find the bookstore I purchased from. but vague memory makes me think it was a online specialty technical bookstore that only sells photocopies from their library copies.( I know, lots a help!)😀

Well worth the read if you can find it.

I could possibly scan a few relevant chapters if needed.

 

Regards
Andrew Martin

 

 

On Sun, May 10, 2020 at 6:14 AM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi Finn

Yes, I’d like the science on inlet lips.

Just reworked our oil inlet and all I have is this drawing.

 

Steve

On 9 May 2020, at 10:15 pm, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:

Opposite of what I understand:
You want a large external radius and a smaller inside radius.

I've in vain been searching for the NACA paper that Tracy Crook get the exact number (internal/external) from. Probably somewhere between 0.5 and 0.8.

Finn

On 5/8/2020 11:02 PM, Terry Adams terrywadams@sbcglobal.net wrote:

You may want to test the lip/airflow on the scoop to your cooling.� Adding a generous radius to the inside may add considerable airflow.� Consult the work and directions given by Peter Garrison and his plane Melmoth (www.melmoth2.com).� jm2c fwiw

Terry

On 5/8/2020 3:34 PM, 12348ung@gmail.com wrote:

Le Roux,

                    You have done a great job so I hesitate to add photos of

my work, but here goes   Neil.

 

-----Original Message-----

From: Rotary motors in aircraft 

<flyrotary@lancaironline.net>

 

Sent: Friday, May 8, 2020 10:31 PM

To: Rotary motors in aircraft 

<flyrotary@lancaironline.net>

 

Subject: [FlyRotary] Re: Rotary Engine Noise

 

Hello Le Roux:

This Frontal photo tells you quite a bit about my cowlings and my airplane.

The top two inlets are for my oil coolers (2 x Fluidyne DB-30416) and the

bottom inlet is for my radiator (Griffin 2-58185-X).

With a "Chubby Cubby" drag is given, things like Aero-Turbine mufflers and

long exhaust pipes (to get noise behind cabin) are not too significant. 

 

 

Jeff: Thanks for taking us aboard the flight over the Ottawa River!

 

I am a relative new member on the group, and are not on terms, with the FWF

installations of the members.

 

Is it possible to post some info of your 13B installation and cowling?

 

 

Thanks Le Roux Breytenbach

 

South Africa

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