What happened to the Bombardier Jet Train?

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What happened to the Bombardier Jet Train?
Posted by zkr123 on Sunday, January 12, 2014 11:13 AM

Why has the Bombardier Jet Train not been put into commercial use? They would be perfect for Amtrak's Cascade route pulling the Talgo's. 

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Posted by Rainhilltrial on Sunday, January 12, 2014 8:48 PM

It's an Acela power car with a jet-engine derivative gas turbine engine. Like all gas turbines, it has two effective fuel efficiency settings ... shut-down or wide-open full bore.

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Posted by NorthWest on Sunday, January 12, 2014 10:04 PM

The main problem, IIRC, is where to run it. The only railroad in the US willing to let trains run as fast as the JetTrain needs to in order to be practical is Amtrak, on the NEC.

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Posted by daveklepper on Wednesday, January 15, 2014 7:41 AM

With this type of technology, Turbos were practical with low fuel prices.  They are inefficient when run at part load.  The genset concept can restore some efficiency, but that adds complications.

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Posted by carnej1 on Wednesday, January 15, 2014 11:39 AM

IIRC correctly ,Bombardier pinned much of it's hopes for production orders for the Jet Train on proposed Florida and Texas high speed rail projects that failed to be built.

 The thought being that the high fuel consumption would be less of an economic deficit when compared to the cost of building and maintaining catenary..

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Posted by Champlain Division on Sunday, January 14, 2018 5:51 PM

What I'd like to know at this late date is what happened to the JetTrain prototype?  The last I heard is that it was languishing in storage at TTI in Colorado Springs.

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Posted by M636C on Sunday, January 14, 2018 10:42 PM

Champlain Division

What I'd like to know at this late date is what happened to the JetTrain prototype?  The last I heard is that it was languishing in storage at TTI in Colorado Springs.

 
I believe that is correct.
 
A point to note not highlighted in this thread is that it doesn't have a turbine.
 
The turbine was leased from the US Marine Corps from a stock held as spares for the Air Cushion Landing Craft which use four of these each for both lift and propulsion. The turbine lease was for the duration of the trials and it went back into USMC stores when the trials concluded.
 
If anyone wanted to run the power car, they could purchase, or lease a turbine as Bombardier did for the trials.
 
But it is basically an Acela power car without a transformer or pantograph. If an Acela power car was damaged, Amtrak could convert the Jetrain car to replace it but that hasn't happened either.
 
But it isn't a complete power unit that people are ignoring. Nobody wants to put up the money to run it, given the cost of buying or leasing a turbine.
 
Peter
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Posted by D.Carleton on Tuesday, January 16, 2018 11:09 AM

Frankly, there's nothing the Jet Train could do that a Charger can't do more efficiently.

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Posted by Norm48327 on Tuesday, January 16, 2018 12:01 PM

Turbine engines do not fare well at low altitude when it comes to fuel consumption.

The denser air at low altitude demands more fuel than it does in the rarified upper reaches of the flight levels. That should explain why long range flights strive to get as high as possible in the fupper flight levels. There is substantial fuel savings to be had at those altitudes.

There are hazards that high off the ground where a sudden decompression of the plane could be instanty fatal to passengers and crew but they are taken into consideration before the flight.

I enjoy flying private and like flying below 15.000 ft. Oxygen is  requieremt a that altitude but I did not find it a problem.

Norm


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Posted by Champlain Division on Friday, September 28, 2018 11:48 AM

Thanks,M636C,

I did not know that about the turbine lease. Even though it’s carcass is rotting in the desert in CO, at least we know where it is.

Can anybody zero me in on where it might be on Google Earth or is it stored inside?

 

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Posted by Leo_Ames on Friday, September 28, 2018 12:25 PM

I was always under the impression that fuel efficency rises because of the lower air temperatures, not because of air density. 

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Posted by SD70Dude on Friday, September 28, 2018 12:38 PM

About 15 years ago this thing came out to Alberta for a promotional tour, pulling one Amfleet coach.  At the time a study had just been completed which recommended upgrading the existing Canadian Pacific Edmonton-Calgary line to handle much higher speeds.  The JetTrain would have allowed this without the initial expense of electrification, and would also have solved the clearance issues around overhead wires.

But nothing ever came of that proposal, and the prototype never returned to western Canada after that tour.

Greetings from Alberta

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Posted by cx500 on Friday, September 28, 2018 12:41 PM

Perhaps lower air resistance in the thinner air too?

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Posted by Leo_Ames on Friday, September 28, 2018 12:43 PM

Seems to be varying answers online, but here's one that matches what I thought was the reason behind it.

https://www.quora.com/Why-are-jet-engines-more-efficient-at-higher-altitude

Lots of stuff out there about air density though as well. I wonder if we have anyone here with a degree in aeronautical engineering that could shed some light now that I'm curious?

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Posted by SD70Dude on Friday, September 28, 2018 1:03 PM

Naturally aspirated piston engines lose power as you gain altitude, with a loss of 2-3% for every 1000 feet gained.  Turbocharging or other forms of forced induction can reduce or even eliminate this derating.

Not sure how gas turbines react though.

Greetings from Alberta

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Posted by beaulieu on Friday, September 28, 2018 1:16 PM

Interesting question. One of the You Tube channels I subscribe to is a flight channel where the pilot flies a Daher TBM-850 turboprop with a Pratt & Whitney Canada PT-6 engine. If the flight is long enough he flies at around  30,000'  depending on direction of the flight. This is for efficiency, cruising speed, and weather.

https://www.youtube.com/watch?v=MwNI8d2-V7s

 

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Posted by rdamon on Friday, September 28, 2018 3:40 PM

Jet engine performance limited by temprature. 

Early turbojets used water injection on takeoff to reduce inlet temprature, also the cooler air is denser and when compressed provide a better fuel/air ratio providing more thrust generation. 

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Posted by erikem on Friday, September 28, 2018 11:43 PM

Norm48327

Turbine engines do not fare well at low altitude when it comes to fuel consumption.

The denser air at low altitude demands more fuel than it does in the rarified upper reaches of the flight levels. That should explain why long range flights strive to get as high as possible in the fupper flight levels. There is substantial fuel savings to be had at those altitudes.

The issue with turbine powered airplanes fuel consumption at low altitudes is that turbine engines lose efficiency when "turned down" - i.e. they do their best running near max power. Most energy efficient flying speed is usually said to be 1.3 times stall speed - at 40,000' feet cruising speed isn't much past the 1.3 times stall speed at that altitude. 100% power at 40,000' feet is quite a bit lower that at sea level, so the engines are running close to flat out at cruise.

Issue with turbines in trains is similar, as the prime mover would be running considerably less then full power most of the time and thus at a lower efficiency. The 4,500HP UP GTEL of the 1950's used about 450 gallons per hour at full throttle and 200 gallon per hour at idle - a 4,500HP diesel engine may use 5 to 10 gallons per hour at idle.

 - Erik

 

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Posted by blue streak 1 on Saturday, September 29, 2018 1:05 PM

It is a lot more complicated than at first blush. First it is the aircraft design.  Higher altitude means less air resistance so less power needed.  There are aircraft that are actualy more efficient at lower altitudes.  The A-300 is one and its most efficient trip altitude ( not fuel consumption ) is between 25,000 ft and 27,000 feet.  It has a high lift wing that akes a lower altitude better.   Since it flies at a lower altitude its true airspeed is much faster than at high altitudes.  Total fuel cosumption is less for a trip.

Outside air temperature is the controlling factor.  The speed of sound is dependent exclusively on air temperature.  Most aircraft are designed to cruise at a defined fraction of the speed of sound  (mach ) .  Usually about Mach .80 although a large differences for biz jets.  Standard temperature "usually" decreases 2C per thousand feet.  Starting at sea level's 15C temp decreasing to about -50C  above that temp remains same so less air resistance,  Now that is just standards and know there are major variations espeially at the poles or equator.

Jet engines actuallly produce less thrust at higher altitudes but the aircraft differences more than make up.  Each model is different of course but as a general rule fuel flow equals thrust . Better later designs have more thrust per pound of fuel flow.

Jet engines, turbo props, turbo shafts that just operate at close to sea level have different designs than a jet designed for high  altitude service.  GE's CF6-50s -80 s are major block cores for back up generators and many navy ships

Point is the Jet train did not use a power plant for close to sea level operation.  A turbo prop or the now proposed external fan jet  ( essentiallly a turbo prop with many blades ) would have been the best for fuel consumption but still the idle fuel flow would have been too much.     

      

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Posted by Overmod on Saturday, September 29, 2018 3:00 PM

blue streak 1
Point is the Jet train did not use a power plant for close to sea level operation. A turbo prop or the now proposed external fan jet ( essentiallly a turbo prop with many blades ) would have been the best for fuel consumption but still the idle fuel flow would have been too much.

The Bombardier JetTrain was like an evolutionary step backward from the ALPS locomotive toward the Amtrak turboliners -- it involves no more than a turboshaft engine driving a transmission.  To my knowledge this involves the same general construction idea as the PT6/ST6 in the TurboTrain, where the traction turbine is free from the stages that drive the compressor and therefore can turn at any required speed while the compressor speed is optimized.  There is no point for 'fan bypass' in these designs, as there is neither prop or reaction thrust; the only output that matters is torque via the power turbine shaft.  This is not a design like the NYC jet RDC that might benefit in some way from high bypass or geared-fan engines.

The high "idle" fuel consumption is a consequence of the required power to run the compressor at required volumetric throughput and pressure to keep the combustors stable in firing.  (That's a different way of looking at what erikem was calling 'turndown')  How much of the resulting combustion gas goes through a power turbine is optional in this design, but any of it that isn't directly used will have to be wasted.

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Posted by erikem on Saturday, September 29, 2018 6:16 PM

The PT6/ST6 design is often referred to as a "free turbine", and also referred to as a gasifier/power turbine combination. The competing Garrett TPE331 engine had a common turbine stage driving both the compressor and the output shaft. The advantage of the TPE331 was much quicker throttle response as the constant speed props kept the whole engine turning at constant speed along with lower fuel consumption at high power. OTOH, the PT6 has a reputation for being an extremely reliable engine and is easier to start as the starter doesn't have to turn the props.

Back around 2008-09, GE was making noises about their new large frame stationary simple cycle combustion turbine having a 46% thermal efficiency at 100% power and 40+% thermal efficiency at 50% power (i.e. 50% turndown). GE's J79 engine of B-58, F-104 and F-4 fame had movable compressor stator blades to improve efficiency a les than 100% power.

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Posted by Overmod on Sunday, September 30, 2018 8:40 PM

erikem
he advantage of the TPE331 was much quicker throttle response as the constant speed props kept the whole engine turning at constant speed along with lower fuel consumption at high power.

This is true, but the analogue for a train (a CVT of some kind) is not really practical even for TurboTrain tare weight.  You may recall (if I recall correctly, it's in a Popular Mechanics article from 1966) that the PT6/ST6 was specifically chosen for being a free-turbine design providing immediate torque at low speed with the 'gasifier' turning at high rpm.  

Most of the recent multispool designs (a couple of geared-fan engines are three-stage) involve driving a fan load for direct aerodynamic thrust; the provision of a 'switch-pitch' vane system (as in some torque converters in the '60s) would be difficult if not dangerous to implement in the power turbine of a lightweight-train style turboshaft engine.  The same issue would probably apply to long-term effective clutching of the compressor turbine to the power turbine at speed,  That's not a happy place for actuators, even those remoted via a sliding torquemeter shaft, to live...

Having said that -- weren't there proposed rail uses for the TPE331 'back in the day'?  I can't find any on the Web, and I wouldn't dare defend them as an engineering solution (vs. an optimized free turbine) but for something like an original-style integral train or HPIT, might they might have been considered? 

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Posted by erikem on Monday, October 01, 2018 9:56 PM

Don't know about the TPE331, but Jerry Pier sent me some info on rail applications for the TF40, which was a 4,000shp engine versus the ~1,000shp for the TPE331. The TF40 was also a dual spool design versus the single spool for the TPE331.

What would make most sense with a TPE331 design would be 3-4 of them in one carbody acting as a genset.

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Posted by M636C on Wednesday, October 03, 2018 12:53 AM

The TF40 is the engine used in the LCAC, rated at 4000HP each.

I assume that was the rating in the Jettrain car.

The Navy is buying upgraded versions with full electronoc control, called ETF-40B.

Peter

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Posted by Champlain Division on Monday, October 08, 2018 11:34 AM

Overmod,

I was closely involved from an advocate point of view when JetTrain was testing and touring corresponding with several different Bombardier and TTC/DOT personnel.

A few technical points, if I may;

JetTrain is, or was, a Diesel Turbine-Electric locomotive.  It’s ST-40 powerplant did not drive a transmission; it drove a generator/alternator.  Also, I know it’s been a long time (close to 20 years ago), but I don’t remember it having a diesel genset for HEP service.  Iirc, the turbine provided that too.

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Posted by oltmannd on Monday, October 08, 2018 2:52 PM

erikem
a 4,500HP diesel engine may use 5 to 10 gallons per hour at idle.

Actually, closer to 3 gph in low idle.  But, your point is solid.  Locomotives spend nearly half their time in idle.  

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by erikem on Monday, October 08, 2018 9:07 PM

I was being conservative in guessing fuel consumption at idle, nice to know I guessed high instead of too low. One of the implications of low consumption at idle is that thermal efficiency of diesel engines won't take a big hit at low throttle positions as compared to combustion turbines.

What impressed me was that the fuel consumption for the 4,500HP GTEL's (~200 gal/hr) is about the same as a Tier III 4,500HP diesel. OTOH, the 4,500HP GTEL's were using ca 1950 technology, where a modern turbine would do much better.

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