Three-bladed vs Four-bladed prop

[wmaxt]

There have been several Corsairs raced at Reno. One was affectionately known as the Super Corsair. It had the redoubtable R-4360 installed and was quite awesome to watch. I was present in Phoenix, Arizona at the races when it caught fire and the pilot bailed out, breaking his legs and arm ... if memory serves. Seems I recall the pilot was none other than John Penney, who recently retired from racing after winning in Rare bear.

the Corsairs were never very good at the races, possibly becuase they weren't nearly so heavily modified as the Bearcats and Mustangs. Most racing Corsairs had stock airfoils, fairly stock wingspans, and fairly stock canopies.

Most winning Mustangs, Sea Furies, and Bearcats have been rather heavily modified from an aerodynamic standpoint.

I know for a fact that Lyle Shelton's Rare Bear, when at racing speed, is more than 40 knots over the design speed of the wing (critical Mach number). That makes it VERY touchy in pitch ... and can easily depart controlled flight, the pitch dampening becomes divergent, making it imperative for the pilot to "stay on top" of the fight path.

Anyway, there have been racing Corsairs ...

Very interesting. I've seen a few racing Corsairs.

wmaxt

 

[sam johnson]

the hellcat is much more powerful than the Mustang, which improved greatly with a 4 blade propeller so it definitely benefits from one. Actually, I'd recommend a 5 blade propeller, like the one made by Hartzell.
The Brazilian Super Tucano uses this propeller and has only 1,600 hp.

 

[FLYBOYJ]

I'd recommend a 5 blade propeller, like the one made by Hartzell.

And do have any engineering data to support this? How do you know that fuel consumption won't go through the roof or any unsatisfactory harmonic vibration will set in? More blades don't necessarily mean better performance.

 

[gjs238]

Many of the German propeller blades appear fat (wide.)

 

[FLYBOYJ]

Many of the German propeller blades appear fat (wide.)

On what aircraft?

 

[Shortround6]

Here is a chart from an old (1940) book "The Airplane and it's Engine" This is just a 21-22 page chapter on propellers and so should not be taken as the last word. There are many complete textbooks on propeller design I apoligise for the poor quality of the scan but hope it is of some interest.

The corrections are in percent and the base line is two-bladed propellers at 200m.p.h. at sea level.

Edit{ the corrections are +33,-13,-19,+7,+15,+22,-8 and -14}