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Questions tagged [contra-rotating]

Use for contra-rotating propellers and coaxial rotors.

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XFY-1 Pogo Contrarotating props alternative?

The Convair XFY-1 Pogo was a tail-sitter VTOL aircraft that used contrarotating props. I believe it was to counter the torque that would be produced if a single prop was used. Why couldn't the Pogo ...
NeelD's user avatar
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1 vote
1 answer
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Can a tail-sitter drone like the XFY-1 Pogo aircraft have any advantage over a classic quadrocopter

I looked at a few rc models of the xfy-1 pogo plane and wondered why there weren't more drones in this setup, some seemed very agile. I think this concept can be refined. of course, the contra-...
San's user avatar
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What is the meaning of "Contra-Rotating Propeller Increases Efficiency"? How is it calculated?

This picture is taken from here. In that video is mentioned that contra-rotating propeller increases efficiency up to 6-16%. Regardless of the number that could be vary from one airplane to another, ...
AirCraft Lover's user avatar
1 vote
0 answers
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What are the expected vibration frequencies in a co-axial rotor system with contra-rotating propellers?

I am trying to understand the frequency spectrum of a co-axial rotor system. Form now i have a RC helicopter with two sets of three gear systems arranged in parallel, The number of teeth are 7,23,27) ...
Nilesh Naik's user avatar
6 votes
2 answers
168 views

Do the blades of the rear disk have different geometry to the blades of the front disk on a contra-rotating assembly?

If my understanding is correct, the air flow is accelerated by the front propeller toward the rear propeller in a contra-rotating prop assembly. Therefore, the rear disk would be receiving air at ...
Whiskeyjar Joe's user avatar
16 votes
2 answers
5k views

Why don't NK-12 powered contra-rotating propellers turn in equal rpm?

The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. The NK-12 drives two large four-bladed contra-rotating propellers, 5.6 m (18 ft) diameter (NK-...
Jpe61's user avatar
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7 votes
5 answers
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Do contra-rotating propellers have the same RPM?

Image source Here is a contra-rotating propeller. The front propeller rotates counterclockwise while the back propeller rotates clockwise. My questions are: Do they rotate at the same speed (RPM)? ...
AirCraft Lover's user avatar
6 votes
4 answers
12k views

Are there disadvantages of coaxial rotor on attack helicopters?

Although the Ka-52 Alligator is a very fierce-looking and formidable aircraft with very powerful engines, it has not seen much export success. Its export is very limited, as only Egypt uses this type ...
user avatar
25 votes
8 answers
31k views

What is the purpose of having contra-rotating props on an aircraft?

Why do planes, like the famous XF-11 and the Tu-95, have contra-rotating props? What is their purpose? Image credit: Mike Freer / Touchdown-Aviation / Wikimedia
Madhav Sudarshan's user avatar