Bill Bradburry wrote:
>
> There have been a lot of these planes.  Howard Hughes built the XF-11
> and damn nearly killed himself with it when it crashed in California.
>
> 
>
>  http://www.absoluteastronomy.com/topics/Contra-rotating_propellers
>
> 
>
The LARC website from NASA had some studies of contra-rotating props
that showed some significant efficiency increases when the blades were
pitched and spaced correctly.  It also allowed more power to be absorbed
with a short prop, a problem that was starting to become a real headache
for designers at the end of WWII.

I am also a proponent of "suck air from around the spinner so that the
inner portion of the prop becomes useful" school of thought.

http://ernest.isa-geek.org/Delta/Pictures/EngineCowling2.jpg

 

The Sun&Fun museum (Florida Air Museum) on the south side of the Lakeland airport has the actual wind tunnel models of that Hughs plane and a gearbox from it's propeller dive system on display.

They also own the only "Pogo" plane. Recently restored. If you visit Sun&Fun or the Museum note that the speed limit on Countyline road (4 lane divided, limited access rural) is 45 MPH and is strictly enforced.

 

Just up I-4 from Lakeland is the Kermit Weeks Fantisy of Flight Museum. Many of the display aircraft are flown monthly. A must see attraction. http://www.fantasyofflight.com/

 

Lynn E. Hanover