Rotorless helicopter tail

[techie_tubby]

Was watching Police Interceptors on CH5 tonight and found out that the South Yorkshire police helicopter hasn't got a tail rotor. Now from what very very little knowledge I have on helicopter airframes I thought that the tail rotor prevented the helicopter from just spinning round and round as seen in countless films, take out the rail and it spins to the floor and crashes. Is this witchcraft with South Yorkshire police? Anyone able to explain in Kamenskoye terms?

 

[JTforever]

Air is forced through and out the end of the tail boom. This counteracts the rotation, in the same way as a tail rotor. Lots of Helicopters use this system.

 

[Odie]

No magic, it's called NOTAR - linky thingy if you're that interested.

 

[roaroftheconwayfour]

Its the NOTAR system. No Tail Rotor. It uses efflux from the helicopters gas turbine engine to offset the torque created by the rotor head. Controlled at the end of the tail boom harrier style with jets of air.

Good for civvy use when dealing with numptys with no cab experience walking upto the cab innocently.
No use whatsoever in 40C+ temps as the higher the OAT (Outside Air Temprature) the lower the performance of a gas turbine engine.
This system uses a considerable portion of the engines power post combustion, in normal turbo shaft engines post combustion engine module is deisgned to squeeze out every last drop of shaft horsepower, but in this case some energy needs to be used for NOTAR.

 

[Rigga]

"...It uses efflux from the helicopters gas turbine engine..."

Incorrect, it uses a fan driven from the main gearbox to blow outside air down the Tail Boom.

Hughes Helicopters proved their concept using a purchased fenestron fan from an AS Gazelle as that was the right size (on a converted Hughes 500 at the time) for the Boom's width.

Original concept only had the steering mechanism at the end of the Boom - but this was later supplemented by the, now common, Blown-Air slot down the Port side of the boom.

 

[Shugster]

As an aside.. you can have twin counter rotating main rotor blades as well.

 

[John Lloyd]

As an aside.. you can have twin counter rotating main rotor blades as well.

And Rotodyne tip jets

 

[Ex-Bay]

I wonder why these thing never fulfilled their potential ?

 

[8:15fromOdium]

Rotodyne was a missed opportunity. I think the main issue was with noise, but there were measures in place to overcome that. It is interesting to compare the Rotodyne to the V-22 Osprey. Very similar in size, but the V-22 carries less. Although it is faster and has better range, but considering we are nearly 60 years on it is not that much better. Perhaps it is time to have another look at the Rotodyne aircraft type.

 

[topstop]

The Eurocopter X3 has its port and stbd propulsion props running at different speed to counter rotor torque.

 

[Stevienics]

I wonder if the MoD project teams have considered doing away with tail rotors and anti-torque measures altogether, and simply training aircrews with a high tolerance for fast rotational speeds under flight conditions?

As for any passengers, it would then be a simple matter to equip winchies with a mop and a roll of kimwipe and cleaning up any resultant gastro-intestinal reflux fluids, once the (very) grateful grunts had succesfully egresed the aircraft.

 

[Jim_P_Pulfrew]

Rotodyne was a missed opportunity. I think the main issue was with noise, but there were measures in place to overcome that. It is interesting to compare the Rotodyne to the V-22 Osprey. Very similar in size, but the V-22 carries less. Although it is faster and has better range, but considering we are nearly 60 years on it is not that much better. Perhaps it is time to have another look at the Rotodyne aircraft type.

It was indeed the noise that made it unattractive to prospective buyers even after the quieter rotor tip jets were installed. The main idea behind the aircraft was city centre to city centre commuter flights and it was just too loud.

Add in the Sandys report and the subsequent take over of Fairey's by Westland as part of the rationalisation of the UK aviation manufacturing base and it was prime for cancellation. Some say it was the civvy version of TSR2 as all the jigs etc were destroyed very quickly by Westland but I don't think it was anything more sinister than a need for space in the factory.

You could point the finger at BEA dithering at placing an order killing it commercially, but the yanks were really keen on a licence build if the noise problem could be mitigated and the USMC were positively howling the place down for a VTOL heavy lift with a decent long range (Something they had to wait a long time after Rotodyne was binned for the less capable V22 Osprey to arrive).

Alas it was in reality another failure to capitalise (and lack of funding one could argue) on Great British innovation.

I always find it ironic that Harold Wilson gave a speech on technology in 1964 in which he talked of a "Britain that is going to be forged in the white heat of this revolution will be no place for restrictive practices or for outdated measures on either side of industry". And then presided over the systematic decline of British industrial expertise (Yes I do know that Rotodyne was cancelled in '62 when the nation was under the Tories).

Jimps

 

[morse1001]

How about the Hughes HH43 Husky?

 

[sumps]

As another aside...the helicopter is the triumph of engineering over commonsense! Off TopicDT_Xtremez_30:

 

[John Lloyd]

Any flying machine where the wing flies faster than the fuselage is odd.

 

[Rigga]

Morse,

It's a "Kaman" Husky - not Hughes.
Kaman is still making helicopters (with a similar counter-rotating Rotor arrangement) is still going strong in many countries.
The Kaman K-Max is well known for its lifting ability and has also been converted to a UAS for US Navy "VertRep" missions.

Another Kaman success was (the USN and RAAN) Seasprite - only recently retired from service after quite a while with both those navies.

 

[Odie]

Any flying machine where the wing flies faster than the fuselage is odd.

It's even odder flying machine where the same wing sometimes flies much faster than the fuselage, then flies much slower.

 

[Ex-Bay]

I was told that a Helicopter does not fly;
they are so ugly, the Earth repels them.

 

[morse1001]

Morse,

It's a "Kaman" Husky - not Hughes
.

Opps!................

 

[Gopher]

A bit like chuck Norris, he doesn't do press ups he pushes the world down.