The Theory Of Helicopter Flight
-
NOTAR:
NOTAR rotor configuration
By far the most recent yaw control strategy developed for helicopters is the NO TAil Rotor (NOTAR) design. NOTAR was first developed by McDonnell Douglas during the 1980s and applied to a modified OH-6 Cayuse. The concept proved so successful that the company began marketing dedicated NOTAR spinoffs of the successful MD 500 family including the MD 520N. The NOTAR system operates by forcing moving air out of slots located on the tail boom. The interaction of this air flow with the downwash of the main rotor is such that it creates a force that opposes the torque of the main rotor. While there are some complex aerodynamics involved, the general idea is to replace a spinning tail rotor with a jet of compressed air squirting out of one side of the tail boom. Varying the strength of the jet gives the pilot yaw control over the helicopter. The NOTAR system is currently available on a number of commercial helicopters including the MD 520N, MD 530N, and MD 600N, and has even made some Hollywood appearances (such as Speed, featuring the lovely Sandra Bullock and the "talented" Keanu Reeves). Though the NOTAR arrangement still requires a long tail boom, the need for a spinning tail rotor is eliminated. This reduces the danger to ground crew, and also allows the pilot to maneuver into positions that he or she normally would not even consider. For example, NOTAR allows a pilot to stick the tail boom into a tree. Try that with a standard tail rotor, and it will be time for an unscheduled landing.
We hope that this in-depth discussion satisfies any questions you might have about helicopter tail rotors. Of course, someone might come up with a better, simpler way of counteracting the force of the main rotor in a few years. Then again, someone might perfect flying saucer technology too, making helicopters a thing of the past. As for me, I'll put my money on helicopters being around for a while... -
Originally posted by kopiosatu:
wow.. a while.. so much faith in the present hovering technology hah.. unless we develop a more economical turbofan engine or a lighter craft structure and weapon load, i think helicopters will be around at least for the next 50 years.
[bWe hope that this in-depth discussion satisfies any questions you might have about helicopter tail rotors. Of course, someone might come up with a better, simpler way of counteracting the force of the main rotor in a few years. Then again, someone might perfect flying saucer technology too, making helicopters a thing of the past. As for me, I'll put my money on helicopters being around for a while...[/b] -
there is the tip jet helicopters.Originally posted by YI:wow.. a while.. so much faith in the present hovering technology hah.. unless we develop a more economical turbofan engine or a lighter craft structure and weapon load, i think helicopters will be around at least for the next 50 years.
and helicopters use turboshaft engines. -
what an idea.. is it still available? anyway.. my turbofan engine were referring to hovering craft/backpack that can hover to at least some ten storey height. will it be possible? only inventions such as these could obsolute the helicopter, else they could be around like forever.Originally posted by kopiosatu:there is the tip jet helicopters.
and helicopters use turboshaft engines. -
You mean like the harriers???Originally posted by YI:what an idea.. is it still available? anyway.. my turbofan engine were referring to hovering craft/backpack that can hover to at least some ten storey height. will it be possible? only inventions such as these could obsolute the helicopter, else they could be around like forever.
who knows what they can come up with... but currently that aircraft can only hover for a very short time, about a few minutes in total i think. -
You mean like the harriers???Originally posted by YI:what an idea.. is it still available? anyway.. my turbofan engine were referring to hovering craft/backpack that can hover to at least some ten storey height. will it be possible? only inventions such as these could obsolute the helicopter, else they could be around like forever.
who knows what they can come up with... but currently that aircraft can only hover for a very short time, about a few minutes in total i think. -
yeap. you are right. hovering technology are currently under hot research. when the runway became a thing of the past, sky dominance will soon follow.Originally posted by kopiosatu:You mean like the harriers???
who knows what they can come up with... but currently that aircraft can only hover for a very short time, about a few minutes in total i think. -
The future choppers will use unconventional helicopter technology, similar that to tof the V-22. Already, Boeing and Bell are competeing to replace the CH-47D/F with such tilt-rotor tech. You should have seen the bell proposal...4 tilt rotors! 2 on each side.
-
well the last time i saw anything on the harrier, the system to me was just in its infancy.Originally posted by YI:yeap. you are right. hovering technology are currently under hot research. when the runway became a thing of the past, sky dominance will soon follow.
but considering the amount of energy, fuel and the system used just to lift up an fighter jet... its more like a liability to me.
like i said its still in its infancy, maybe some aviators here might wanna follow up on any new reports on hover flight? -
you were referring to the osprey.. is it. if i didn't remember wrongly.. there were a huge design fault over its tilt-rotor blade. think the blade hit each another blade and the whole plane crash.Originally posted by eurofighter:The future choppers will use unconventional helicopter technology, similar that to tof the V-22. Already, Boeing and Bell are competeing to replace the CH-47D/F with such tilt-rotor tech. You should have seen the bell proposal...4 tilt rotors! 2 on each side. -
Yeah. THe fault should have been fixed. Ospreys have begun carrier landings not too long back.