WIX Archives
Re: Well, I considered to recline in my chair ......
Posted by Christer on Mon Nov 11, 2002 10:56:19 AM
In reply top Re: Well, I considered to recline in my chair ...... posted by Cees Broere on Mon Nov 11, 2002 10:00:18 AM
Well, not only had some time passed between the design of the Spitfire and the Mustang, they weren?t designed to do the same job. The Spitfire was an interceptor-fighter whereas the Mustang was an escort-fighter.
The aerodynamics had improved, yes it had but, not for all good. Talk about laminar flow and laminar profiles had been started but all wartime profiles are laminar flow to some extent. The one of the Mustang is more so than the one of the Spitfire.
IIRC there?s something called the laminar pocket. This is a range of angle of attack where the drag is very low, around a load factor of 1G. This is used in the Mustang to gain the cruising performance where the power requirement is proportionally smaller than in the Spitfire, less HP/MPH that is.
When you get out of that laminar pocket it?s pay-off time. In the climb and loaded up in a turn the older profiles were better and that?s why the Spitfire outclimbs and out turns the Mustang. The Mustang requires more power to sustain a 5G turn without altitude loss than the Spitfire.
If you compare the P-51D with the Mk.VIII, using the basically same engine, the P-51D is 10 % faster but the Mk.VIII climbs 10-20 % better and out-turns the P-51D.
(I?m aware that it isn?t really as simple as this but I?m not writing a book.)
I?m not sure about this but the radiators weren?t as bad as they look. They provided some thrust from the exiting hot air and the equation was close to zero drag in total.
A different shape, such as the wider ones of the Spiteful, would have been better. A different position than under the wings would also have been better, such as the scoop of the Mustang. The Tempest Mk.I had the radiators buried within the wings and it was very fast, some 25 mph more than the Tempest Mk.V.
The best thing would be to bring your "Gold Card" to the Isle of Wight and order a Spiteful, hook up a highly modified ex. Shackleton Griffon 58. On a standard Griffon 69 at +25 psi boost it was in a 480 mph hurry already ......
Christer