the power of jet engines...
 

I have a reasonable idea of what 60,000lbs of thrust means for a 747 engine, I think. But I try to explain to a friend and it means nothing. Anyone know any good analagies that help appreciate the power and energy used during a 7/8hr flight?

I once heard sth like the fuel used by a B747 flying LHR - JFK would take a car to the moon and back, if there was a road! Any others?

After 14 years working with jet engines. The
only one I can remember is that at
take off power a JT9D use 4 gallons
a second, US gallon that is.

Well I'm impressed.

Thrust is FORCE.

If you had, for example, 10,000 pounds of thrust available then that would be sufficient to be able to hold up an object weighing 10,000 pounds. If you had 10,001 pounds of thrust then you could RAISE a 10,000 pound object off the ground, and then hold it above the ground.

So a 747 with 60,000 pounds of thrust per engine (or about 27,300 kilograms if you prefer) could LIFT a 27,299 kilogram lorry off the ground and HOLD up.

747 has four engines each with about 60,000 pounds (27,300kg) of thrust you say? Well thats a total of 4 x 60,000 = 240,000 pounds (or 109,000 kg if you like).

If it helps with perspective, most articulated lorries have a gross vehicle mass of about 40,000 kilograms, or 40 tonnes.

Im sure someone once told me that at a certain altitude a jet engine of 5000lbs produced the same thrust as 4 X 2000hp piston engines with very efficient props.

Not sure if its true though. He might have been the same bloke that got a 319 stuck in a (an?) hold.

here's a good example (the comment is by yours truely)
http://www.ilovebacon.com/vehicles/070500.shtml

all I know is that jets produce alot of hot air.....

Refering to my trusty P&W Handbook the relation between thrust is expressed by the following: THP = F x mph/375 Where THP is Thrust Horse Power, F is thrust in pounds and mph is miles per hour. Doing the math on a 60,000 pounder going at M.80 at MSL one would arrive at 97,000+ horse power. A figure that I cannot relate to. I kinda like the 4 gal per second thing.

Aren't there some other gems, like a B747-400 at idle power, produces more power than a Trident did at full power, or some such like?

If an engine is producing 60,000lbs at MSL what is it producing at altitude at M.80? I suspect we would all be suprised at the very low figure. Any enlightenment out there?

[This message has been edited by Thrust (edited 18 October 2000).]

HP= TV/325 (I think the 375 someone mentioned above is for mph)

because w =Fd

and Power = w/t = Fd/t

and V=d/t

so Power also = FV or TV

so using 1 HP = 550 ft-lb/sec

HP = TV/550

or in knots HP=TV/325

Doesn't help with the mental imagery though, as a -400 at 1 knot msl/isa etc is putting out around 700 ponies, whilst at 340 kts it's pumping 230,000 horses.

A CF6-50 on T/O thrust displaces about 600 cubic meters of air per second.

really a lot of hot air.

In the end they are all noisy BRT's. (big round things)

If a 747 applies full thrust,
1.000 woman 100 meters away could
dry their hairs ........

isn't that an impressive example ?

cheers
ef

EF,
Shouldn’t that be ‘fry’ their hairs?

If you could fill up your Ford whatever with the same amount of full as a B744 and you drive an average of 10'000 miles a year. You would'nt need to re-fill for a 144 years.


------------------
-------------------------
You fly em we'll fill em!

A Rolls Royce engineer was interviewed on telly recently, and he held a blade (about 3 inches long) out of the power turbine in a Trent engine in the palm of his hand. Can't remember the exact text but I think he said that one blade took the same power out of the gasflow as a Formula one racing engine develops. And it sits in a gasflow which is at a temperature of more that twice the melting point of the blade. It's only because the blade's air cooled internally that it doesn't instantly melt.

Amazing stuff.

SSD

A level 3 Mc Donalds could fry up 37065208 Big Macs with the fuel capacity of a 737? Fact or Fiction

Goldie -

I think you made that up.

No goldie!

It are 74.130.416 cheeseburgers !!!

Now, with a Rolls engine, at take off, the amount of 'suction' from this 747 engine will suck a person in from 8ft. and throw them out 120ft. the other side!!!!!!

Perhaps they could make it a new theme park attraction???!!!