Vought-Sikorsky VS-311 Rotating Wing Aircraft

[Bill S]

Here is a general arrangement of a Rotating Wing Aircraft proposal the Vought-Sikorsky VS-311
The aircraft was designed in response to Air Corps Proposal 40-260 dated 12-20-39 as amended
5-28-40. From the VAHF archives.


I have some Inboard Profile drawings coming up.


Does anyone know anymore of the Air Corps proposal, did it lead to the development of an aircraft like the R-4 (VS-316)?


bill

 

[hesham]

Wow,many thanks Bill,you made my day,


also Pitcairn PA-38 and Platt-LePage XR-1;


http://www.secretprojects.co.uk/forum/index.php/topic,10093.msg94420.html#msg94420

 

[Bill S]

Here are the Inboard Profile with a different series of uses for the aircraft.
For the War Department it shows a gunship
For the US Postal Service it shows a 500lb mail payload
For the US Agricultural Department it shows an Insecticide Dispenser
And a view for an Experimental Ship.
From the VAHF archives.


bill

 

[Stargazer]

What an AMAZING find! Designation wise, this makes it Sikorsky's FIRST helicopter design after his VS-300 and -300A prototypes, which makes it even more amazing given how advanced a design it is!

I can't say enough how grateful and indebted I am to you Bill S for digging this one out. A million thanks!

 

[bigvlada]

Very intriguing design, main rotor plus two tail rotors. What was their purpose, main rotor wasn't powerful enough?

 

[Orionblamblam]

My *guess* is that they were thinking that various loads would move the CG fore and aft enough to require moving the center of lift fore and aft.

 

[Orionblamblam]

Looks like the cockpit designer moonlighted for Focke Achgelis...

 

[Anachronus]

The similarity of cockpit design is probably just parallel evolution.

 

[Orionblamblam]

Indeed. A combination of not-very-high top speeds, a need to be able to look more or less straight down and the simplicity of flat sheets of glass might drive designers towards these similar concepts.

... but it's aliens.

 

[joncarrfarrelly]

Very intriguing design, main rotor plus two tail rotors. What was their purpose, main rotor wasn't powerful enough?

They were a part of Sikorsky's thinking at the time, their function was similar to that of the elevators on
a standard aircraft. In most particulars the VS-311 is basically an enlarged VS-300.

http://www.sikorskyarchives.com/VS-300_Helicopter.php

 

[hesham]

The same drawing from Sikorsky archives 3-2000,


and anyone explain if there is a "DS" designation mentions in it.


http://www.sikorskyarchives.com/pdf/News%20Mar%2000%20R-4.pdf

 

[riggerrob]

Very intriguing design, main rotor plus two tail rotors. What was their purpose, main rotor wasn't powerful enough?

Igor Sikorsky was still learning how to control helicopters. His cyclic was a long way from perfected. Try to think of the two different tail rotors as a rotary rudder (controlling yaw) and a rotary elevator (controlling fuselage pitch).

 

[Wurger]

OrionBlamBlam said:

Looks like the cockpit designer moonlighted for Focke Achgelis...

Most likely the opposite. The Sikorsky design looks more primitive compared to the german design, dating from 1939, and never leaved the drawing board. The german design was flying in that same year.