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**hunter48820** · 07-15-2009, 04:31 AM

Yes but what is the "maximum ceiling" of the 700?

**Neil_M** · 07-15-2009, 05:08 AM

Who knew indeed. That's very impressive for a land beast.

Are the most modern diesel-electrics as powerful as the most modern big steam was when that went out? (Q4s, Big Boys, etc)

**Pruitt** · 07-15-2009, 06:35 AM

I'm afraid that your conclusion that a 747 couldn't budge a 700 is incorrect.

A 747-400 with P&W engines generates 63,300 punds of thrust for each engine. That's a total of 253,200 pounds of thrust (four engines).

That's several times the tractive effort of the 700.

With locomotive brakes set, the 747 could pull 3 700s, with a bit of power to spare. That's assuming that the 700 is trying to pull in the opposite direction - 69,800 pounds force tractive effort per locomotive in one direction (total force 209,400 lbs for 3 locos) against 253,200 lbs in the opposite direction. The 700 drivers spin one direction, but the locos are dragged helplessly in the opposite direction. 747 wins easily.

With loco brakes set, the 747 would easily drag the loco along the tracks. With A/C brakes set, one 700 would spin its drivers fruitlessly as it failed to drag a max-gross-weight 747.

Can a 747 lift the 700? No way. On the other hand, a 700 can't lift a 747, either.

By the way, the C-17 is only one many A/C more powerful than a 747.

**Peterpools** · 07-15-2009, 02:33 PM

Nope, the Champ has to be the Space Shuttle. Today at liftoff, the Shuttle weight was 4.5 million lbs and the thrust generated at liftoff: 6,425,000 lbs of thrust.

Peter

BCT

**SteveH** · 07-15-2009, 04:18 PM

Neil,

It's hard to say. Most steam locomotives were rated by tractive effort or drawbar horsepower whereas diesel-electric locomotives are rated by engine horsepower or tractive effort. I guess comparisons have to be made by tractive effort because drawbar horsepower and engine horsepower are two different things.

The drawbar rating goes way back to dear old James Watt watching the horses unload ships on the docks (or so the story goes). He figured that one horse could move 550 pounds 1 foot in 1 second.

So the calculation goes as such:

Horsepower = Force (in pounds) times distance (in feet) over(divided by) (33000 times time (in minutes))

Engine horsepower is usually given as Brake Horsepower from a rotating shaft ie.the engine crankshaft.

This formula is :

Brake Horsepower = Torque of shaft (in foot-pounds) times shaft speed (in RPM) divided by 5252

This brake horsepower is more than the drawbar horsepower of a diesel-electric locomotive due to parasitic losses including the auxiliary generator and heat creation in the main and auxiliary generator among others.

If I'm wrong, don't be afraid to let me know.

**Pruitt** · 07-16-2009, 01:26 AM

quote:

Originally posted by Peterpools

Nope, the Champ has to be the Space Shuttle. Today at liftoff, the Shuttle weight was 4.5 million lbs and the thrust generated at liftoff: 6,425,000 lbs of thrust.

Peter

BCT

If we're looking at past machines, too, the Saturn 5 generated 7.5 million pounds of thrust at liftoff... [:-bigeyes2]

**hunter48820** · 07-16-2009, 02:35 AM

I dunno, my Pontiac Aztek is pretty darn powerful!! Of course , I can't tell you what the exact drawbar horsepower or max tractive effort is!!

**jaynjay** · 07-16-2009, 03:32 AM

I based my conclusions from the following

http://www.sps700.org/boeing747.html

My statement about the 747 not being able to budge the 700 was based on the 747 carrying the 700. The 700 weighs more than the max payload of the 747.

As far as thrust versus drawbar pull. The engines have to move the 747 also. Somewhere along the line coefficient of fiction has to play a role.

I only meant this topic to be a fun fact.

**hunter48820** · 07-16-2009, 05:56 AM

Hi John,

I found it fun!!

By the way, it always amazes me how something like this can bring out so much information from so many knowledgeable people. Pretty enjoyable even if some (okay, much) of it is over my head!

**Pruitt** · 07-16-2009, 06:17 AM

quote:

Originally posted by jaynjay

I based my conclusions from the following

http://www.sps700.org/boeing747.html

My statement about the 747 not being able to budge the 700 was based on the 747 carrying the 700. The 700 weighs more than the max payload of the 747.

As far as thrust versus drawbar pull. The engines have to move the 747 also. Somewhere along the line coefficient of fiction has to play a role.

I only meant this topic to be a fun fact.

I thought it was fun, too. My reply wasn't meant to chide you. I was just responding to your post with some other "fun" facts. It wasn't meant to come across otherwise. My apologies if it did.[:-angel]
Another interesting thing to consider - the 700, in traveling from Seattle or Portland to Spokane, was/is outrageously more fuel efficient than a 747 making that same trip...

**jaynjay** · 07-16-2009, 07:10 AM

I guess know one caught my tongue-in-cheek reply with the coefficient of "fiction".

No hurt feelings on my part. Like I said, it was just a fun fact that I found and wanted to share. You have to take everything from the internet with a grain of salt.

As far as the 700 making it to Seattle? Well, it never did...as a scheduled stop that is. The SP&S never made it to Seattle

**hunter48820** · 07-16-2009, 08:01 AM

Hey John, I saw that but thought it was just a spelling error and was afraid to give you a smart a** response using the word "fiction!" Next time I'll know!!

**bitlerisvj** · 07-16-2009, 08:09 AM

I find this subject interesting. I have always been fascinated by the C&O Allegheny 2-6-6-6. I was never sure if that was the most powerful Steam locomotive ever built or was the Big-Boy? The C&O weighed 775,300 lbs and had a tractive effort of 110,200 lbs. To me that sounds just absolutley amazing. I know there may have been bigger steamers built but I think they didn't count, like the N&W Jawn Henry and the C&O turbine.

How does 110,200 lbs of tractive effort compare to todays modern diesels?

Regards, Vic Bitleris

quote:

Originally posted by SteveH

Neil,

It's hard to say. Most steam locomotives were rated by tractive effort or drawbar horsepower whereas diesel-electric locomotives are rated by engine horsepower or tractive effort. I guess comparisons have to be made by tractive effort because drawbar horsepower and engine horsepower are two different things.

The drawbar rating goes way back to dear old James Watt watching the horses unload ships on the docks (or so the story goes). He figured that one horse could move 550 pounds 1 foot in 1 second.

So the calculation goes as such:

Horsepower = Force (in pounds) times distance (in feet) over(divided by) (33000 times time (in minutes))

Engine horsepower is usually given as Brake Horsepower from a rotating shaft ie.the engine crankshaft.

This formula is :

Brake Horsepower = Torque of shaft (in foot-pounds) times shaft speed (in RPM) divided by 5252

This brake horsepower is more than the drawbar horsepower of a diesel-electric locomotive due to parasitic losses including the auxiliary generator and heat creation in the main and auxiliary generator among others.

If I'm wrong, don't be afraid to let me know.

**hon3_rr** · 07-16-2009, 10:31 AM

This is why some of us are engineers... and I'm not talking trains.... Souds like physics 504....

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