How do twin rotor helicopters, like those of the Chinook at Dartmouth, avoid their blades clashing each other?
Answers:
Despite the different heights of the blades, they would still hit if they weren't synchronized. The blades do flap and it also has something called cyclic trim in which the heads tilt fore and aft for flight at different airspeeds to maintain a level fuselage attitude in flight. During ground taxi, the forward head also tilts forward, to pull the aircraft along.
The synchronization is accomplished by a shaft that runs between the forward and aft transmissions. Both heads rotate together at the same speed and stay meshed due to this synch shaft. Failure of this shaft is most likely catastrophic to the rotor blades as they get out of synch.
They are set at different heights above the main body of the helicopter.
They could have one blade higher than the other or too far from it to interact with it. Or they could just synchronize them so two blades were never in the same position at the same time (sort of the like the fokker chain gun). Not a hard problem, anyway.
synchronicity of the blades. check out the firemax helicopter, very interesting set-up with their blades, the configuration negates the need for a tail rotor.
It's all in the timing, they rotate in the same direction where they intersect, and one is a little higher than the other
one set of blades is slightly lower, the also helps with stability as the previous muilty blade chopper with the rotars at the same height spun, alot
One set of blades is higher then the other on a Chinook the rear blades are higher then the forward blades.
There is a relatively complicated gearing system that ensures the this does not happen. .
On occasion this system has failed, resulting in a couple of crashes - on the whole it's a robust system.
There's more detail in the depth of here:
http://www.faqs.org/docs/air/avch47.html.
different heights as far as i am aware
the blades rotate on different planes
Complex (very !) gearing combined with different hub-heights
Despite the large blades being at a different height when they slow down after landing they drop. This is all taken care of in the software timing programme as these helicopters are highly computerised.
Just like the blades of a hand mixer. They are geared to mesh with each other. This system was engineered in WW1 to allow fighter pilots to shoot their machine guns through their propellers without shooting them off. Timing is everything!
They're synchronized.
they are timed to pass between each other
the height of the blades
WildBill846 answered perfectly. I would have just given him the thumbs up, but I'm not a level 2 yet. :)
They are at different heights. A little nugget of usless information:- there is 3 gearboxes controlling the 2 rotors.
The fore rotor is several feet lower than the aft rotor, They're far enough apart to compensate for blade sail (blades bend up or down during operation.
Height has nothing to do with synchronising the rotor. The rear rotor is higher so it can be tilted forwards without slicing the body. The front rotor naturally has nothing to hit.
The rotors are driven through a gearbox and are set up to "miss" each other. As each rotor head cannot turn independently they cannot smash into each other unless a drive shaft breaks or the gearbox blows.
set at different heights from the front is lower than the back wild bill got it in one so am not wasting time typing it out again
HI
It's nothing at all to do with the height of the rotors and all to do with the shafts that run between the gearboxes, the blades inter-mesh in most flying conditions so they must be kept synchronised or all you end up with is a large brick and lots of bits of blade. It is not done through software, but a bloody big shaft, much safer than software and much less likely to fail (please note that in most situations were things need to be kept synchronised on aircraft, it is USUALLY done mechanically)
Ex RAF Rigger (airframe fitter)
still rigging just for someone else
Rog
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