These types of gear box propellers were used extensively during the wars in torpedo drive systems. The counter rotating props helped to neutralize directional rotating torque to keep the torpedoes running straight and true with minimum necessity for more complex guidance systems
Yes you are correct. To avoid such situation, pitch angle also called as blade angle of the two propeller set is made to be opposite to each other, which means if blade of propeller 1 is sloping down towards right side then the blade of propeller 2 will be sloping towards left side. This arrangement can also be in vice versa. This kind of blade arrangement now forces the air stream towards only one side even though the propellers are spinning in opposite directions. The side at which air flows is dependent on direction of rotation of the input shaft. There are propeller designs in which we can vary the pitch angle of the propeller blade dynamically that is even while the props are in rotation and they are called as variable pitch propellers. Pitch can be controlled to generate thrust either in forward or in backward direction. When air is forced to flow on front side of aircraft reverse thrust is generated. Backward or reverse thrust is helpful in slowing down the aircraft after touchdown while landing. When air is forced to flow on back side of aircraft forward thrust is generated. Forward thrust is the thrust that propels the aircraft. When pitch angle is set at feathering position it wont generate thrust and aircraft will not move considerably. This is helpful while starting the engine in order to reach the required engine RPM without generating thrust.
Gear 2 has a hollow short shaft through which the red colour input shaft passes through and rotates freely. This short hollow shaft is placed in the front bearing that is fixed in the Gear cage. So the Gear 2 is getting placed in the front bearing just like an ordinary bearing and shaft assembly. Now Gear 2 rotates freely with its bearing. Input shaft simply passes through the hole at the centre of Gear 2 and its hollow short shaft.
propellers are turning the wrong direction. unless its a pusher configuration. if it were a helicopter it would never take off, its pushing air up, not down.
Propeller rotation direction depends on direction of rotation of input shaft. This is a simplified demo for contra rotating propeller using a bevel gear box. Based on engine rotation direction the pitch angle of the props will be determined for pusher or puller configuration. For Helicopters the lift will be always upwards (air will be pushed always downwards) and the engine will be turning in the appropriate direction with respect to the pitch angle. For example most of American helicopters with single prop will turn in counter clockwise direction, so engine will be spinning appropriately with respect to blade pitch angle. But for Russian helicopters it will be turning clockwise direction. So to get the required thrust that is lift, pitch angle will be set in such a way. These are fixed design parameters and they don't change for their entire lifetime. Prop pitch angle and engine direction of rotation which is the input determines whether the prop will be pusher or puller. These parameters can be set to our wish during the design stage itself. Here in this video no engine is attached, so input shaft direction can be set to CW or CCW.
Most of the contra rotating propeller designs are of puller configuration due to increased efficiency. Pusher propellers are popular with single prop designs.
These types of gear box propellers were used extensively during the wars in torpedo drive systems. The counter rotating props helped to neutralize directional rotating torque to keep the torpedoes running straight and true with minimum necessity for more complex guidance systems
Thank you for making this video 🙏🏾 I could swear that this was strictly made for me
Shouldn’t the propellers have been turning in the opposite direction cutting the wind and sending it in the opposite direction ?
Yes you are correct. To avoid such situation, pitch angle also called as blade angle of the two propeller set is made to be opposite to each other, which means if blade of propeller 1 is sloping down towards right side then the blade of propeller 2 will be sloping towards left side. This arrangement can also be in vice versa. This kind of blade arrangement now forces the air stream towards only one side even though the propellers are spinning in opposite directions. The side at which air flows is dependent on direction of rotation of the input shaft. There are propeller designs in which we can vary the pitch angle of the propeller blade dynamically that is even while the props are in rotation and they are called as variable pitch propellers. Pitch can be controlled to generate thrust either in forward or in backward direction. When air is forced to flow on front side of aircraft reverse thrust is generated. Backward or reverse thrust is helpful in slowing down the aircraft after touchdown while landing. When air is forced to flow on back side of aircraft forward thrust is generated. Forward thrust is the thrust that propels the aircraft. When pitch angle is set at feathering position it wont generate thrust and aircraft will not move considerably. This is helpful while starting the engine in order to reach the required engine RPM without generating thrust.
Compact very neat and simple, can said double drive contraprop be fitted to a race prepared Pratt&Whitney R-4360-63A Radial?.
👍👍👍👍👍👍
I was wondering how the front bearing support both yellow and red propellers? Kindly please advise its structures, thank you in advance.
Gear 2 has a hollow short shaft through which the red colour input shaft passes through and rotates freely. This short hollow shaft is placed in the front bearing that is fixed in the Gear cage. So the Gear 2 is getting placed in the front bearing just like an ordinary bearing and shaft assembly. Now Gear 2 rotates freely with its bearing. Input shaft simply passes through the hole at the centre of Gear 2 and its hollow short shaft.
Thank you very much for your reply. Great demo!
Very nicely shown n thnx
Thank you.
propellers are turning the wrong direction. unless its a pusher configuration. if it were a helicopter it would never take off, its pushing air up, not down.
Propeller rotation direction depends on direction of rotation of input shaft. This is a simplified demo for contra rotating propeller using a bevel gear box. Based on engine rotation direction the pitch angle of the props will be determined for pusher or puller configuration. For Helicopters the lift will be always upwards (air will be pushed always downwards) and the engine will be turning in the appropriate direction with respect to the pitch angle. For example most of American helicopters with single prop will turn in counter clockwise direction, so engine will be spinning appropriately with respect to blade pitch angle. But for Russian helicopters it will be turning clockwise direction. So to get the required thrust that is lift, pitch angle will be set in such a way. These are fixed design parameters and they don't change for their entire lifetime. Prop pitch angle and engine direction of rotation which is the input determines whether the prop will be pusher or puller. These parameters can be set to our wish during the design stage itself. Here in this video no engine is attached, so input shaft direction can be set to CW or CCW.
Use?
Great
must be a pusher
Most of the contra rotating propeller designs are of puller configuration due to increased efficiency. Pusher propellers are popular with single prop designs.
And the united states claims it couldn't build an engine that would work reliable.
Yeah the US be capping on this one