Gas turbines

[Nick_Walczak]

Just looked up the spec for one of these (usually used in helicopters).

Power: 420bhp
Weight of engine: 70kg
Output RPM: 6000rpm (same as a car)
Fuel: LPG!

Why aren't these babies used in sportscars?? :)

[Jezz_S13]

Cos there is no accelaration. :)

[Nick_Walczak]

:confused: 420bhp = no acceleration??

Perhaps I am missing something - do these things have poor power outputs at low rpm?

[Jezz_S13]

Originally posted by Nick_Walczak
:confused: 420bhp = no acceleration??

Perhaps I am missing something - do these things have poor power outputs at low rpm?

Yeah I think so, there was a land speed car using a gas turbine to drive a gearbox but it took ages to accelarate.
i imagine it would be a little more popular too if it were viable. The sound would probably put some people off too. :D:D

[RichardM]

Many, many years ago, I seem to remember Rover (when it was Rover) having a street going gas turbine prototype.

Which then disapeared without a trace!

[Nick_Walczak]

Bah, rev it to 6k in nuetral and dump the clutch :D

6 speed close ratio gearbox -> sorted :)

[Nick_Walczak]

Linkage:

http://www.gasturbine.pwp.blueyonder.co.uk/allison.htm

Look for "Car " for a link to a racing car that was built with one of these puppies.

[shadow21]

The link for "bikes" doesn't work :rolleyes:

[Nick_Walczak]

Nah but the car one does. The nutters drove it on the public highway :) check out the mpegs.

[Mr_Sukebe]

Why would it have no acceleration?

I seem to remember that the Navy fitted gas turbines to it's frigates (I know, not quite comparable) and that the key benefit was it's fast acceleration when compared to a diesel.

Still, maybe the Navy should be sourcing diesels from BMW or the new VAG 150hp 1.9.

[davidra]

Originally posted by Mr_Sukebe
I seem to remember that the Navy fitted gas turbines to it's frigates (I know, not quite comparable) and that the key benefit was it's fast acceleration when compared to a diesel.

Maybe the engines reach high "idle" speeds and when engaged are already in the high power output range?

[Mr_Sukebe]

Well here's a thought:
1. The navy has sourced the most awesome torque convertor known to man (should really be trying to sell it onto Viper owners)
2. I guess that when you engage drive, it's not that the prop would be turning against a stationary object. Still, I would have expected their to be some reaction and stress incured as shock loading on the drive.

Here's another thought for you.
Imagine you have a submarine with a single prop on the back. How do they prevent the sub simply rotating on it's axis?
I assume that it would be similar in it's torque rotation to a helicopter, but how many subs have you seen with a rear rotor?

[Will Taylor]

The Americans also use them in their M1A1 tank, thanks to the immense amount of power they generate - unfortunately they also generate obscene amounts of heat, so you'd need a mother of an IC to run it! :D

Plus they drink loads of fuel at idle, and are rubbish if you put them under a fluctuating load - like, for example, traffic!

As for subs, they probably have their control surfaces set to counter it, just like there are some helicopters with fins to counter the rotation. There are also subs with counter rotating propellors in serial, again, just like a couple of helicopters eg the KA-50 Werewolf

I have definitely played too many "Jane's" combat simulators.

[davidra]

Originally posted by Mr_Sukebe

Imagine you have a submarine with a single prop on the back. How do they prevent the sub simply rotating on it's axis?

They have horizontal and vertical fins plus it is presumably easier to move the water than the sub?

[Mr_Sukebe]

Wild>

Good point mate. I recently read a factual account of Desert storm from the point of view of the General in charge of the US VII corps (written by Tom Clancy). In there, the general mentioned that the M1 used as much fuel at tickover as it did whilst moving, not so good when you have a vehicle with the fuel consumption of a super tanker even when moving.

More seriously, I think he said that they needed to get approx 1 million gallons of fuel a day to the corps in question during the 4 days of fighting. Imagine trying to get Esso to do that?

The logistics for the Gulf war were simply awesome, just so much to move around over such great distances.

Still, then you put it in context that the US moved several hundred miles within 4 days.

How the f..k did the Germans achieve the rate of progress that they did in 1940 with horses and carts still moving a lot of their equipment, that truly was awesome.

[davidra]

Originally posted by Mr_Sukebe
the M1 used as much fuel at tickover as it did whilst moving,

I think this supports the idea that they basically wind the engines up at idle and use a heavy duty clutch type thing?

[RichardM]

http://www.conklinsystems.com/firebird/mlife.shtml

http://www.gasturbine.pwp.blueyonder.co.uk/rover2.htm

[AshT_200]

Most Subs are Nuclear Powered these days. A bit excessive for an S13

[Ivanski]

Acceleration might be poor, but top speed would be something else.
There's something about the sound of a GT starting up that makes me grin like a nutter :D

Have a look at http://www.gas-turbines.com/
for what you can do with a GT and an old boat!

Now 1200hp worth of GT in an Ultima, sounds like fun,
just need a custom diff and a dragster autobox :D

Cheers

[andyf]

Am I missing something? Gas turbine engines / turbine dragsters don't drive gears, they simply push the car with thrust, surely? Unless I've got quite confused with some other turbine, they start off slow and build up - like watching a rocket take off or (bless it) Thrust SSC-1. Hell, Thrust was a right slow thing getting off the line but 500-700mph was pretty easily dispatched :) Turbines don't particuarly like changing speeds like a car turbo so trying to get one to rev up, then drop down as you change gear and rev back up again .. hrm.

[Billy]

That's a turbo-jet, Andy.

Modern propeller aircraft use gas turbines (well, turboprop ones do!) and they're basically the same engine layout, exept for the gearbox driving the prop. Incidentally, turbojet engines use gears to produce the various compressor stage speeds, so you just slap another on the front and voila!

They'd be a pain in the butt for a car though. Imagine going through all the rigmarole that planes do just to start the fecker! Come to think of it, I know how that feels....(not anymore :) )

[Nick_Walczak]

One thing I thought about - a turbine probably has a shedload of momentum so if you revved it up to 6000rpm in first gear, then engaged clutch and changed to second, in the time you dip the clutch, it probably hasn't lost more than 500rpm so unless you have a CVT or something, it just won't cope with changing gears.