^why?

http://forums.pelicanparts.com/uploa...1563753514.jpg

https://en.wikipedia.org/wiki/Contra-rotating_propellers

http://forums.pelicanparts.com/uploa...1563755416.jpg

Simple answer (or probably WAG) from another layman:
Is that "stall" is the lack of airflow....due to low speed or turbulence....over both the airplane wings or props.

The blades can't grab air in a complete vacuum or very high altitudes.
When this happens everything becomes a rock.

With counter-rotating props the front blades act as sort of a turbo for the rear blades.
Instead of being enveloped in nothingness, they now work in a pre-pressurized envelope.

So regardless of conditions:
-slow and low -vs.- high and fast
-either the front set or the back set should be able to pull at full capacity...at the slight cost of inefficiency with the other set.

forgot pic
http://forums.pelicanparts.com/uploa...1563757801.jpg

Celine was a probe to test your defences.

http://forums.pelicanparts.com/uploa...1563764209.jpg

Computer people: Can you please explain this glitch in the matrix?
1). This image was downloaded from the net and stored onto my hard drive.

2). I uploaded it from my hard drive directly to Pelican Parts.

3). The upload took a long time.
"Transferring from Imgur............"

4). WTF?

You probably saved it from a Russian website and now your computer and all the Pelican Parts servers are PWNED by Mother Russia.







http://forums.pelicanparts.com/uploa...1563775453.jpg

I'm calling BS on that one.
If the fronts are sucking vacuum the rears would get prepressurized vacuum just the same, 2x0 is still 0.

But they are something like 10-15% more efficient, but that has nothing to do with vacuum, or high altitudes, it's just inherent efficiency across the performance envelope compared to single prop of similar size and blade design.
And it's offset again by higher weight and maintenance needs due to complexity..

I think the main advantage on that plane shown, cargo, is smaller diameter prop, so better clearance from the ground, safer, and better for dirt strip landings where stuff might be in the bushes, i don't know.
+ VSTOL performance and ability to feather the second prop once airborne and cruising, so better fuel efficiency.

https://upload.wikimedia.org/wikiped...amey_Logan.jpg

After WWII when the Soviets took all the V2s and 262s with BMW 003 and Junkers 004 engines and everything else, over 6000 engineers and scientists, some paid, some forced labor, the "team" developed the Bear turboprops from those 003 and 004 designs

Aside from that, Soviets bought 55 Rolls Royce Nene engines used in the Mig 15s
Technical assistance from the West was ongoing from 1917 on, Reverse engineered Caterpillars were converted to metric, DC3 complete factory sold to the Soviets(the LI-2)Ford Model A was the GAZ exact replica- and these days the RD-180 rocket engines are sold to the US