Mailing List flyrotary@lancaironline.net Message #64960
From: William Jepson wrjjrs@gmail.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] airflow characteristics-radiators and spinner
Date: Tue, 9 Jul 2019 14:03:38 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Group something else to note is that even in the P51 duct later models had a wing section to help direct the airflow into the top section of the duct. The idea has always been to slow the airflow to take advantage of whatever fin pitch is used and then to pinch the duct again to re-speed the airstream to near to the aircraft speed. Never 100% obviously but as close to it as possible. Now I going to pass along a possibility for cooling that I have told a few people but not many. There are a bunch of conformal radiators available to us for a reasonable cost that I am amazed nobody is using. High-performance motorcycle radiators. I worked for Kawasaki years ago and did a lot of engine building even into the water-cooled era. Several motorcycle manufacturers have built beautiful curved aluminum radiators to increase the cooling available on some of their  highest performance models. I have attached a jpeg of the radiator from a Kawasaki ZX7R. 750cc engine rated at about 110 HP. Very high heat rejection requirements. Lots of these components available from motorcycle salvage yards. often with minor damage to the end tanks, but for our use we might modify them anyway. Fitting one, (or two), of these curved radiators inside a cowl would be easyand effective. You might never get a radiator man to make you a ring radiator, but you can buy some that might conform very well to an in-cowl mounting.
Bill Jepson

On Tue, Jul 9, 2019 at 11:21 AM Marc Wiese cardmarc@charter.net <flyrotary@lancaironline.net> wrote:

Interesting discussion recently found---

M

This document is shared with you in response to various questions arising out of spinner airflow characteristics. It is TOO LENGTHY to include in full, but you may find parts interesting enough to share.

 

[Here's a French version of the English document I found that's easier to see/read.]

 

http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Moteur/Refroidissement/Conception/Cooling_systems_for_automotive_conversion~H.Mayer.pdf

 

[I find it odd that he misses a major point that did emerge from those decades of engine cooling research: cooling fin pitch is very important!

Nowadays, most folks use the free software from GM_Harrison and others to design their coolers... but the delta P in automotive applications is generally less, but the airflow is greater. So a different fin pitch is appropriate for our relatively higher delta P (much higher speed through the air than a car) but lower airflows (to minimize cooling drag) applications.]

 

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