Fisher P-75 versus Davis Manta

[KJ_Lesnick]

I was thinking about the subject of propeller-clearance and the original design was based around a 6'2" prop with a four-bladed contra-rotating propeller (eight blades in total): While I'm not really sure the effects of the number of propellers for a given disc-area, even for guesstimates, I was told that if you doubled the propeller area you'd double the thrust provided there was enough horsepower to drive it.

The V-1710 had half the displacement of the V-3420, so doubling the area in theory would double the thrust: While the projections for the V-1710 were originally gauged to be around 1,150 hp and it would, in practice, be more like 1,325 or more with turbocharging, most other aircraft seem to have been built around these premises and did fine. 

With twice the propeller area, this would yield the following...

• Disc Area: 59.733893649505925 square feet or 8601.680685528853234 square inches
  
• Disc Diameter: 8 feet 8.651803615609056 inches or 104.651803615609056 inches
  

...based on the original 6'2" diameter four-bladed contra-rotating propeller used on the outline.  The propeller shown in the diagram is actually 8-ft, 3/7-in, so this isn't too far off actually.

As for issues regarding ground-clearance, should that pop-up: I have a bit of a solution, even if it may be a bit bizarre, it has been used in practice.  The P-47 had a landing-gear which telescoped 9-inches to provided adequate ground-clearance.  Though it probably required creativity and a lot of testing, it actually proved to make for little trouble in practice.

[wuzak]

That's a lot of decimal places....

[famvburg]

I knew the F8F used a telescoping landing gear. Never knew about the P-47 tho!

[KJ_Lesnick]

I got some information via a guy on ww2aircraft.net, he said that with the struts fully compressed the minimum acceptable clearance was 7" for tricycle gears and 9" for conventional gears.  He said he couldn't get a straight answer on whether fully compressed meant maximum weight or just weight on the wheels.