[iraghava]

Originally Posted by xinome

did you guys see the exhaust on that hawk, that must spit fire and must produce one hell of a roar for the engine

Actually no. Since this is a turbine engined bike it produces a high-pitched shriek rather than a roar, but still it is quite loud. Revs quite high IIRC even by bike standards.

[extreme_torque]

Finally i can say to a yamaha R1 owner "Your CC in my BHP" :P

[Ram]

Originally Posted by ram

It is powered by a Rolls-Royce Allison 250-C18 gas turbine engine



The engine puts out 320 bhp@52,000 rpm and 425 ft-lb of torque.

Originally Posted by iraghava

Since this is a turbine engined bike it produces a high-pitched shriek rather than a roar, but still it is quite loud. Revs quite high IIRC even by bike standards.

1. The turbojets of the old Air-India Boeing 707-437,
2. the turbofans of their Boeing 747 and
3. the turboprops of the ATR-72, flown by Jet Airways, Kingfisher and Air-Deccan
   
   are all gas turbines of different configurations.

The 707-437 had Rolls-Royce Conway bypass turbojets;
the 747-400 has high-bypass turbofans;
the ATR-72 has Pratt & Whitney turboprop engines.

However what's used in a helicopter is a fourth kind of gas turbine -- the turboshaft.

Turboshafts differ in that they have a free power turbine spool that can spin at a different rpm from the compressor-turbine combination.

And I might add, while the Y2K's Allison turbine does 52,000 rpm, the compressor does 54,000 rpm.

These're a good 10X the rpms, that reciprocating engine folks are used to!

Ram

[-GS-]

How about this 3800 Horse Power Jet Bike.

Engine: Rolls Royce Viper MK.202 Turbojet
Thrust: 2450 lbs approx 3800 HP + after burner another 1200 HP

More information and pics on: World's most powerful Jet Bike

[Ram]

Back in the old days, when we were kids (as in kindergarteners),
a motorcycle was an impossibly tall bicycle.
It had a big cyclopean eye -- a big headlight, that reluctantly reached full brightness when switched on and faded out lazily when switched off,
the flat egg-shaped tank, the ethereal smell of petrol,
fat tires that seemingly belonged more on a car than a bicycle,
and a thunderous sound like a frenzied drummer venting his anger on his drum.

It offered the challenge to climb onto it when no one was looking,
but with the risks -- that one could fall and bruise their knees and elbows
and worse still, that it could fall onto you and you'd need an adult to get it off.

But the fun of sitting tall, cruising with wind in the hair was always a wistful attraction.

Perhaps emotions such as these, inspired these tall wheeled structures.





Comments welcome!

Ram

[vabs78]

Originally Posted by ram

1. The turbojets of the old Air-India Boeing 707-437,
2. the turbofans of their Boeing 747 and
3. the turboprops of the ATR-72, flown by Jet Airways, Kingfisher and Air-Deccan
   
   are all gas turbines of different configurations.

The 707-437 had Rolls-Royce Conway bypass turbojets;
the 747-400 has high-bypass turbofans;
the ATR-72 has Pratt & Whitney turboprop engines.

However what's used in a helicopter is a fourth kind of gas turbine -- the turboshaft.

If I am not mistaken Jet engines work on Jet propulsion principle instead of turbine principle. Are these engines Jet engines? Or do they drive the propellers?

[Ram]

Originally Posted by vabs78

If I am not mistaken Jet engines work on Jet propulsion principle instead of turbine principle. Are these engines Jet engines? Or do they drive the propellers?

@vabs78, I'm not sure how you mean that the "Jet propulsion principle" is different from the "turbine principle". But let me explain, the way I've understood.

The term jet engine and gas turbine is interchangeable.
All of the varieties, I described are gas turbines (very loosely called "jet engines") that burn aviation kerosene to convert thermal energy into kinetic energy -- in specific -- into the high rpm spins of one to three turbine spools.

However they propel their host vehicles in different ways.

The turbojet is a gas turbine that produces thrust by by reaction alone.
Let me try to explain, as simply as I can, how it works.

The engine is spun up to start it,
by using compressed air (as in commercial aircraft)
or by using an explosive charge (as in some military aircraft).

The rotating engine's compressor sucks in air via the intake.
This air is compressed to a higher pressure and sent into the combustion chamber.

In the eddy of a flame holder, aviation kerosene is mixed with the compressed air and ignited by flame.

As the hot combustion gases leave the combustor, they expand by spinning a turbine in their path.
This converts thermal energy into kinetic energy.
The turbine is on the same spool as the compressor and keeps the whole system spinning. This sustains continuous operation of the engine.

The expansion process cools the turbine exit gas temperature and also reduces the pressure. Still, both temperature and pressure are still very very high.
As the hot gas stream exits the turbine via the propelling nozzle, it produces a very fast jet in the exhaust plume.

The momentum (mass x velocity) of the exhaust stream is more than the momentum of the intake stream.

Thus, there is a net forward thrust upon the vehicle.


Turbojets are by nature noisy and heavy on fuel consumption.
Somewhere down the line researchers found that matching the speed of jet efflux to the speed of the aircraft, reduces noise and increases efficiency. The jet efflux could be reduced by using part of it to power a ducted fan.
To that end the bypass turbojet was invented (aka turbofan).

A turbofan (as in the Boeing 747's power plant) is a turbojet with a ducted fan on the compressor.
A small part of the the airstream passes through its turbojet, but most of it bypasses it.
The ducted fan produces most of the thrust while a small quantity produces thrust by reaction.

My favorite deviation is the very high bypass ratio General Electric CF700 turbofan. It had a fan-on blade (“Flade”) connected directly to the low-pressure turbine rather than to the compressor as is more common.

A turboprop (as in the ATR-72’s powerplant) is a turbojet where the kinetic energy generated in the turbine goes through a reduction gearbox and turns a propeller. The spinning propeller produces most of the thrust while a very small quantity
of efflux from the nozzle still produces reactive thrust.

A turboshaft (as in a helicopter’s powerplant) is a turbojet where all the combustion gases are used to turn a free turbine. The free turbine drives reduction gearboxes which deliver torque to the main rotor and to the tail rotor.

Some of the latest turboprop engines also have a free turbine to tap the energy in the residual hot combustion gases.

Thanks for your patience, and hope I was able to explain clearly.

Ram

[Rehaan]

Originally Posted by ram

YouTube - MTT Marine Turbine Technologies Y2K

I really love the little CG snippets they throw in to the video, starting with that fast sweeping left turn.... and the part where the y2k flys by the parked cars and their windows shatter

Any idea if there is a full CG promotional video available?

cya
R

[Sankar]

Originally Posted by Rehaan

I really love the little CG snippets they throw in to the video, starting with that fast sweeping left turn.... and the part where the y2k flys by the parked cars and their windows shatter

Any idea if there is a full CG promotional video available?

cya
R

That CG is part of the climax from the movie Torque.

The hero on Y2K is actually trying to catch up with the baddie who's on a v-twin with NOS,possibly H-D. It was pretty lame.

[Rehaan]

Lol,

Thanks for that info Sankar..... i guess it would have been cooler if it was just a 1min promotional vid for the y2k...

cya
R

[vabs78]

Originally Posted by ram

@vabs78, I'm not sure how you mean that the "Jet propulsion principle" is different from the "turbine principle". But let me explain, the way I've understood.

The term jet engine and gas turbine is interchangeable.
All of the varieties, I described are gas turbines (very loosely called "jet engines") that burn aviation kerosene to convert thermal energy into kinetic energy -- in specific -- into the high rpm spins of one to three turbine spools.

Thanks for the elaborate explanation Ram, and I know that all this information is accurate.

But I am still not convinced about your statement "The term jet engine and gas turbine is interchangeable."

Basically, in a Jet engine we are trying to convert chemical energy into kinetic energy but to directly induce linear motion and not rotational motion.

The simplest Jet engines burn the fuel in a combustion chamber and direct the expanding gases through a nozzle. This generates a reactive force on the nozzle (according to the Newton’s 3rd law of motion) which propels the nozzle in the opposite direction of gas flow.

Hypothetically there is no need of any rotating parts in such an engine.

Practically however, the fuel needs oxygen to burn. This brings the compressor into the picture (to suck in air which will be used as source of oxygen) and a turbine to drive the compressor.

If (liquid) oxygen is supplied to the combustion chamber then again we don’t need a compressor/turbine. This is done in space craft engines which are essentially Jet engines.

Gas turbine engines on the other hand are trying to convert chemical energy into kinetic energy but to induce rotational motion. This rotational motion is then used to drive mechanical devices like wheels or fans which will again convert the motion into a linear motion of the vehicle.

Please let me know if I am missing something here.