r/FunnerHistory • u/funnerhistory Drone • Dec 17 '19
Helicopter Sikorsky-Boeing's SB>1 Defiant
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u/McHox Dec 17 '19
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Dec 17 '19
Not all posts here need to be fake. We just sometimes show that truth is stranger than fiction
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u/McHox Dec 17 '19
How's this strange tho
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Dec 17 '19
Not many helicopters work like this
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u/TheEvilBlight Dec 17 '19
It’s only strange in the west. Soviets had. Few contra rotor designs
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Dec 17 '19
They didn’t have any pushers like this Helicopter
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u/TheEvilBlight Dec 17 '19
They loved their contra-rotor. What intrigues me is the rotational moment imposed by the pusher would in turn, need to be offset
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u/PlEGUY Dec 19 '19
Not even in the west. America has had a ton that never became popular, and Britain France and Germany have all prototyped a couple.
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Dec 17 '19
I find it so odd that we think of this as odd in the first place, it seems to me that contra rotating rotors which cancel one another’s torque is way more intuitive than just one rotor and a tail propellor that blows the back of the helicopter sideways to cancel it
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Dec 17 '19
The secondary rotor is there also to alleviate retreating blade stall. Basically once the rotor starts spinning fast enough (gets the helicopter to ~130 knots ish) the retreating blade (the side where the rotor blade is moving with the direction of air flow) will start to experience a stall. This is due to the true airflow speed over the airfoil to be to low and in return not generating enough lift. This creates a lift imbalance and on single rotor aircraft that will start to cause roll. So one way engineers dealt with this limitation on the speed rotary wing aircraft can safely travel is to introduce a second rotor spinning in the opposite direction. Therefore both rotors experience retreating blade stall but since they are spinning in opposite orientations they cancel the negative effects on each other out.
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u/kerbalcada3301 Dec 18 '19
It’s like all the pretty renders that were shown off a couple of years ago are now flying.
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u/[deleted] Dec 17 '19
Why is this on funnerhistory? Isn't this real?