Jet Powered test vehicle

markshipman · Post by **markshipman** » Fri Jul 19, 2002 12:15 pm

I've just found this thread on train-sim.com, check it out

http://www.train-sim.com/cgi/dcforum/dc ... ewmode=all

warriorgoku · Post by **warriorgoku** » Fri Jul 19, 2002 1:04 pm

The trent 900s are capable of 96000lbs of thrust, how many horsepower is that?

DrkAngel · Post by **DrkAngel** » Fri Jul 19, 2002 2:33 pm

Looks like fun

MartinH · Post by **MartinH** » Fri Jul 19, 2002 7:01 pm

I've downloaded it but not tried it yet.

BTW, you can't convert pounds into horsepower (apples and oranges so to speak).

Martin

delticbob · Post by **delticbob** » Fri Jul 19, 2002 8:46 pm

Didn't BR try jet powered snow blowers half a century ago?

Bob

bjdick · Post by **bjdick** » Sat Jul 20, 2002 10:41 am

You can convert Lbs thrust into HP Martinh,otherwise how do aircraft designers know what engine specs are required?Concorde's engines were designed for the aircraft,not the other way around.
With a little research,you'll find the answer.Watt did.

MartinH · Post by **MartinH** » Sat Jul 20, 2002 1:50 pm

For your information, since your knowledge of physics is clearly lacking, horsepower is a unit of power and lb is either a unit of mass or force depending on whether you're talking lbm or lbf. Trying to convert a unit of power into a unit of force is like trying to convert someone's weight into height. The link between force and power is speed. An aircraft designer knows how fast he wants his aircraft to fly and can model the aerodynamic drag at that speed. At cruising speed the required thrust (in Newtons or lbf if you're still in the dark ages) is equal to the drag (calculated by multiplying the dynamic pressure by the cross-sectional area and Cd). The required power in Watts is then obtained by multiplying the speed in m/s by the thrust in N and adding on 15-20% for losses in the system. If you really want HP,then 1HP = 750 Watts.

As for doing some research, I've done a few years of it and have the qualifications to prove it. How about you?

Martin

warriorgoku · Post by **warriorgoku** » Sat Jul 20, 2002 3:09 pm

I know you can't convert horsepower into lbs of thurst, what i was wanting to know was how many horsepower is the trent 900 when its running at full spec?

It must be somewhere near 120,000 horsepower.

bjdick · Post by **bjdick** » Sat Jul 20, 2002 3:48 pm

Without developing a flaming session.According to the above,a jet engine in a test bed,at full output,is producing no power!-as it's not moving.Nonsense.It doesn't know whether it's on a plane,boat or other vehicle,it's just doing its thing.
TIME is a component taken into consideration,when calculating power,a fact often missed completely,when a specific power is quoted.One horsepower is 33,000Ftlbs per Hour!
With a full understanding of the above,a power rating for a specific thrust can be arrived at.Yes I am qualified,a Marine Engineer,plenty of HP there,8000HP\CylinderX12Cylinders.How about propellor thrust?

delticbob · Post by **delticbob** » Sat Jul 20, 2002 4:09 pm

'orse power....thought thats what my roses 'ad!!

Bob

dilflat · Post by **dilflat** » Sat Jul 20, 2002 6:00 pm

I just tried the jet sled out. it is great fun, phenominally fast and the kids (of all ages) will love it.
It really needs sound files though, or do 777's really sound just like a couple of GP38's.

I rather like the US railcar with the two jet engines bolted to the roof. There is something wonderfully crude but functional about the whole idea.

Time to go and put together "Jet sled passenger activity"

Dave.

bjdick · Post by **bjdick** » Sat Jul 20, 2002 6:26 pm

To answer warriorgoku,the rated power output of the Trent,marine propulsion gas turbine is 50MW.It doesn't move within vessel either.Well I hope not

MartinH · Post by **MartinH** » Sat Jul 20, 2002 7:40 pm

Wrong again bjdick

Of course it moves. The turbine and compressor both spin and have to work against friction and aerodynamic drag. The result is that air is heated and accelerated. In the ship, the end result (I hope) is that the ship moves. In your conversion factor you talk about ft lbf/hour. Where do you think the ft comes into it? One foot pound is the work done when one lb of force moves 1 foot in distance. Power is then defined as the rate of doing work.

True you don't have to have movement, what matters is energy conversion. For example, a 1 kW heater converts 1000 Joules of electrical energy into heat energy per second.

My point was a simple one. A pound is a unit of force and a horsepower is a unit of power. How many pounds you get for a certain number of horsepower depends on the machine in question. In locomotive terms, you may have two locos with exactly the same engine (same hp), but the tractive effort of one is much higher than the other (i.e. more lbs), because of the gear ratios. You won't find a generic conversion factor. lb ft/hr into hp yes, but not lbf into hp.

I'm not asking for an argument here nor the opportunity to lecture, but I resent being told to do some research like a little kid.

Martin

DaveR · Post by **DaveR** » Sun Jul 21, 2002 10:16 am

Hi All,

On Trainsim.com there is a turbine engine, file name "bblowup2" this has the turbine sounds, I read that these sounds are a lot better in this machine than the sounds that come with it

MartinH · Post by **MartinH** » Sun Jul 21, 2002 10:55 am

"bblowup2", now that sounds fun.