wonwinglo

http://www.texnology.net/Movies/crash.wmv

Well here is the answer,note how quickly the helicopter gains momentum once the tail gearbox fails,if that tail rotor malfunctions then you have had it.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

squiffythewombat

Barry, where do you mange to find all these random clips?

wonwinglo

*** Well Squiffy as mentioned before,Scale-models has agents all over the globe sending in hundreds of photographs a day to give you the cream of whats new in reports,a force to reckon with as we have the technology ! that chopper tail rotor failure was an excellent example of how unstable helicopters really are without counteracting forces ie anti torque devices.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

squiffythewombat

o0o0o right cool! i was thinking along the lines of "my god this mans a google super genuis" lol!

Yeah totally see what your saying with the chopper, i guess the gyroscopic forces being unbalanced would be near enough impossible to stableize once that sort of momentum is gained!

wonwinglo

Some years ago a news photographer was involved in a Bell 47G helicopter crash,the tail rotor gearbox failed and the helicopter started to spiral violently,he kept the camera running and the effects caught on film were terrifying,this was the first time that anyone had managed to film something like this from inside the helicopter.
I am surprised that more use has not been made of the counter-rotating or intermeshing rotor principles in the West,these forms of drive totally eliminate any form of tail rotor,take a look at the Kaman helicopters and some of the Soviet ones as well,fine so engines will always fail,but at least while they are running the torque is effectively eliminated.
Anyone who flies model helicopters will understand the principles applied,and above all know exactly what happens when that small set of rotors at the back fails !

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

squiffythewombat

yeah, having played extensive pc flight sims, and also flown several RC choppers i know exactly what you mean. A good pilot can sometimes keep her level but even thats near enough impossible because of the momentum.

I believe, correct me if im wrong but wasnt steve hislops death blamed on rear rotor failure? it failed so the main rotors tilted backwards chopping off the tail or something like that?

When you say counter-rotating do you mean one rotor spins as the other stops? like in a car engine?

wonwinglo

*** Squiffy,counter rotating means that the two seperate sets of blades are geared together,one to turn in a clockwise direction and the other in an anti-clockwise direction,this totally eliminates and also balances out any torque effect of the spinning rotors with no need for a tail rotor.
Steve Bishop was killed when the main rotors cut the tail off from his Robinson R.22 helicopter,this is called rotor slap induced by a negative force on the control column,this phenomenon can be noticed sometimes on model helicopters after an heavy landing when the blades strike the boom,you notice a ding in the boom,after this everything has to be checked out as something is bound to be bent.Things are more serious on full sized machines.

The thing with helicopters is that they are inherantly unstable and need to be flown all of the time.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

new to trains

my brother in law is an avionics engineer working on full size copters, he has had to crawl into the tail booms on full size copters to degrease and inspect running gear to the rear tail rotor after this type of incident has occured in full size aircraft, heavy landings can mis align tail rotor drive shafts and bearings.... he says the biggest headache ( literally) is the solvent degreaser they use in the confined space !-

__________________
just gotta keep building !

squiffythewombat

LOL won, you see thats exactly what i first thought, then i thought to my self- dont be silly the rotors turn in the same direction but i totally see what you mean now!

steve bishop? ermmm ops! lol!

i remmber hearing that rotor blades have a stupidly low lifespan actually on the aircraft!

wonwinglo

Squiffy said-
'i remmber hearing that rotor blades have a stupidly low lifespan actually on the aircraft!'

Wonwinglo replied-
Yes most blades are now made from composite materials,the continual flexing of these degenerates the structure and integrity of the blade,manufacturers work alongside the airworthiness authorities to set a life limit on the blades.
Recently in Australia some Robinson R-22 helicopters were shedding blades,the reason was that the hours of the rotors had not been recorded in the log books,the helicopters were being used for cattle roundup operations where a probe gives a sharp shock to the animal and moves it on.
But you are right the blades do have a life span,and are expensive to replace.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/