[tankerwanabe]

Recently, there's been radical changes in engine technology for automobiles. The marriage of turbine + electric motors are resulting in engines with 2x horsepower, and running 2x miles per gallon.

Just the thought of doubling range on most aircrafts (or tanks) are pretty incredible.

Are there current developments to develop hybrid engines for the military?

[dpapp2]

Le plus ca change, le plus c'est la meme chose...

http://www.landships...egs/B-zug_4.jpg
http://www.landships...tchamond_22.jpg
http://www.landships...electric_04.jpg

This post has been edited by dpapp2: 03 December 2007 - 1257 PM

[Lambda]

tankerwanabe, on Thu 29 Nov 2007 0747, said:

Recently, there's been radical changes in engine technology for automobiles. The marriage of turbine + electric motors are resulting in engines with 2x horsepower, and running 2x miles per gallon.

Just the thought of doubling range on most aircrafts (or tanks) are pretty incredible.

Are there current developments to develop hybrid engines for the military?

Google for "ACEC Cobra".
That was a projected M-113-like APC family by Belgian firm ACEC, which was to feature hybrid drive with separate sprocket-driving electric engines. Several prototypes were apparently running but the project got shelves for want of customer interest (heh) and peace-dividends budgets. First prototype was built in 1980...
Also I distinctly remember reading a report about experimental Hummers kitted for the US forces some 10 years ago when no one was talking about hybrid cars yet...
As to whether there are hybrid-drive vehicles projected right now, I frankly have no idea, and I am (not too much) surprised that no one tried integrating it to e.g. new-generation APCs or UGVs.

[Tony Williams]

Yes, this is the current focus of development in armoured vehicle chassis technology (both wheeled and tracked). Developments in lighter and more compact motors and batteries are making this much more feasible.

It has particular benefits in wheeled vehicles, especially 8x8s. Instead of a very complex and bulky transmission, with a gearbox and lots of driveshafts which can make deadly spears to penetrate the vehicle if it hits a mine, they are just putting a compact motor in each wheel hub, which only requires a power cable to it. The IC engine then just becomes a power generator. Much simpler, and with the additional advantage that it ensures that lots of electric power is available for all of the systems fitted these days, plus in the future laser or electromagnetic rail gun weapons.

[Ivanhoe]

tankerwanabe, on Thu 29 Nov 2007 0147, said:

Recently, there's been radical changes in engine technology for automobiles. The marriage of turbine + electric motors are resulting in engines with 2x horsepower, and running 2x miles per gallon.

Just the thought of doubling range on most aircrafts (or tanks) are pretty incredible.

Are there current developments to develop hybrid engines for the military?

First you have to define the term "hybrid". What folks are now calling hybrid in the automotive sense is a power system using a small internal combustion engine plus an electric motor/battery system. The IC engine is sized for average power load, and the electric motor/battery provides the difference between the engine's max output and the max total power load. Regenerative braking minimizes the amount of power wasted in stop & go driving.

For aircraft, hybrid technology isn't going to help. Peak loads last for many minutes (i.e. climbout from SL to 30,000 ft AGL), which would make the battery weigh more than the base aircraft. And there's not a lot of braking done by aircraft except on the landing roll.

[dpapp2]

There are about three different types covered under "hybrid". First is the classical gas/diesel electric vehicle, where only the transmission is electric - like those WWI vehicles. Then there is serial and parallel hybrids, whether the wheels are driven by electric motor only, or both by the engine and electric motors, where electric motors are only 'secondary'. Their advantage is not in the electric propulsion itself. They store energy in their batteries, which is available for high loads, e.g. acceleration, so the IC engine and the generator can be smaller for given everyday performance.

The DARPA developed Humvee alternative has less than half the consumption.
http://www.military.com/soldiertech/0,1463...Shadow,,00.html

[Mikel2]

:lol:

http://www.geocities.com/Pentagon/Quarters/4635/tanks/elefant/ferdinand_destroyed.jpg

[rmgill]

The most sustained use of Hybrid Electric Engines I can think of are Diesel Electric Locomotives. Traction Motor/Generators in the trucks powered by a large generator powered by a large diesel engine. With some good battery or capacitor technology, energy storage from regenerative braking could assist with the energy conservation.

[EchoFiveMike]

Right, but locomotives use electric drive motors because of the mechanical and weight issues with large transmissions, not any sort of fuel conservation. They have resistors which generate load/heat when the motors are used for braking. Similar arrangements are used on the giant dumptrucks and loaders used in mining. S/F.....Ken M

[sunday]

EchoFiveMike, on Fri 30 Nov 2007 0604, said:

Right, but locomotives use electric drive motors because of the mechanical and weight issues with large transmissions, not any sort of fuel conservation. They have resistors which generate load/heat when the motors are used for braking. Similar arrangements are used on the giant dumptrucks and loaders used in mining. S/F.....Ken M

And also due to the lack of reliability of high-power, multi-output shafts mechanical transmissions, and to the better matching (in the beginnings, without power electronics) of power characteristics of the DC-series electric motor with the traction load. Also, to reduce the amount of unsprung masses in the chassis. Finally, as four- and six-powered axis vehicles are quite usual, so putting 4 or 6 electric motors is mechanical simpler than having a lot of differentials. Plus the electric braking, inherently more reliable and low maintenance than pneumatic brakes with drum or discs and friction pads (although some mechanical braking is still necessary as the simpler electric brakes don't work at zero speed)

This post has been edited by sunday: 30 November 2007 - 0257 AM

[dpapp2]

In any definition of hybrids I'd include the capacity to store significant amount of energy for later use, to differentiate from diesel/gasoline electric transmissions which were present in first-generation tanks and artillery tractors. The latter can be used by today's electronics to store energy, although there are very few trains that can use this. Mainly because the energy storage needs for a locomotive is much higher than for a Prius. IIRC there's a diesel hybrid train operating in Japan.
Regenerative braking for pure electric trains (EMUs) is much more useful. They can feed back energy from regenerative braking into the electric grid, decreasing the effective power consumption train, by up to 30% for a commuter train.

When tracks have axleload limits, trains and locomotives usually use hydraulic or mechanical transmission. For larger axleloads only electric transmission is used. One of the reasons is that large axleloads are preferable for higher traction, so the considerably higher weight of the DE transmission is not an issue.

[sunday]

The demise of turboelectric propulsion in USN battleships came as a result of the weight restrictions contained in the treaties of the 1920s. Now, with much lighter equipment we are seeing the return of electric propulsion in escorts, and amphibs.

[George Newbill]

On those Hybred Hummers, one was immersed in seawater and ruined, it was "Donated" to an educational institution where it now serves as a test bed for aspiring engineering students. I see it driving down the street daily. All the running gear is stock, the electrics/electronics/batteries are prototypes.

[Mikel2]

I guess the S-tank qualifies as a hybrid. What were the benfits of the turbine/diesel powertrain?

[rmgill]

EchoFiveMike, on Fri 30 Nov 2007 0004, said:

Right, but locomotives use electric drive motors because of the mechanical and weight issues with large transmissions, not any sort of fuel conservation. They have resistors which generate load/heat when the motors are used for braking. Similar arrangements are used on the giant dumptrucks and loaders used in mining. S/F.....Ken M

All mechanical connections to multiple trucks isn't easy. The driving trucks HAVE to be able to swivel and you don't want them changing angle based on torque input through a shaft. Articulated steam locomotives had all drivers of a given set anchored to one frame.

The other problem is developing a clutching mechanism for disconnecting the power that doesn't need LOTS of service for long use and lots of accelerations. Direct drive systems without a torque converter (be it hydraulic or electrical) are complex and underpowered since you can't get the same range of torque conversion you can with a Diesel Electric. Road and yard slugs allow you to use even MORE energy spread across more drive motors where the prime mover alone with that generator would normally burn out the drive motors at the lower speed higher tractive effort (torque) levels with heavy consists or steep grades. There were examples like the Fell locomotive which had 4 separate diesel engines with a very complex gearbox and a peculiar hydraulic clutch system which was filled to engage it, the system lacked power for its complexity.

Steam Locomotives not having gearboxes either since they exerted force on their drivers based on their

[JOE BRENNAN]

Diesel-hydraulic loco's of medium HP are common in Europe and elsewhere, just never made it on North American railroads; matter of style, local conditions, particular failures of particular models (when a few diesel hydraulics were sold into US many years ago), etc.

On actual hybrid loco's, GE plans to offer a road locomotive with battery banks to store energy from regenerative braking rather than dissipate it as heat in dynamic braking resistors as is standard on diesel electrice loco's now. And RailPower Tech of Canada is having success marketing the Green Goat switcher which has large battery banks and only small diesel generator. Switching loco is a very friendly duty cycle for a hybrid.

Joe

This post has been edited by JOE BRENNAN: 01 December 2007 - 1237 PM

[Mobius]

Speaking of hybrids, in this months Scientific American there was a small article of a hybrid turbine-pulse detonation engine. Pratt & Whitney is developing one for the air force. The pulse detonation jet engine was first used by the Germans in WWII in the V-1 rocket. When done properly this is the most fuel efficient type of jet engine. Unfortunately the annoying buzz would ban it from airports worldwide. But when used in conjuction with the turbine this is muffled. The fuel efficiency is said to be on the order of 2x a normal turbine jet engine.

[Ivanhoe]

Mobius, on Sun 2 Dec 2007 1020, said:

Speaking of hybrids, in this months Scientific American there was a small article of a hybrid turbine-pulse detonation engine. Pratt & Whitney is developing one for the air force. The pulse detonation jet engine was first used by the Germans in WWII in the V-1 rocket. When done properly this is the most fuel efficient type of jet engine. Unfortunately the annoying buzz would ban it from airports worldwide. But when used in conjuction with the turbine this is muffled. The fuel efficiency is said to be on the order of 2x a normal turbine jet engine.

The noise is not the only downside. Pulsejet engines experience a vey high cyclic stress loading, which results in fatigue failures. Fine for one-shot and disposable unmanned vehicles, but not for manned craft. The necessary teardowns and NDIs for cracks would make operating cost prohibitive, like Space Shuttle prohibitive.

[JWB]

Pulse detonation engines are not the same as pulse jet engines.> http://en.wikipedia....tonation_engine

[exT70]

Tony Williams, on Thu 29 Nov 2007 1353, said:

Yes, this is the current focus of development in armoured vehicle chassis technology (both wheeled and tracked). Developments in lighter and more compact motors and batteries are making this much more feasible.

It has particular benefits in wheeled vehicles, especially 8x8s. Instead of a very complex and bulky transmission, with a gearbox and lots of driveshafts which can make deadly spears to penetrate the vehicle if it hits a mine, they are just putting a compact motor in each wheel hub, which only requires a power cable to it. The IC engine then just becomes a power generator. Much simpler, and with the additional advantage that it ensures that lots of electric power is available for all of the systems fitted these days, plus in the future laser or electromagnetic rail gun weapons.

When the Rooikat was upgraded a couple of years ago, one of the options considered was a dualdrive system. It was surprisingly simple to do and dilivered really impressively, way past what was expected, and than from a relatively low technological base. Due to the experimental nature and testing yet to be done (read no funds), the dual drive was not implemented, as was most of the improvements suggested, but apparently the project is ready for implimentation, needing only funding. I have had the oportunity to speak to some of the enigineers, and they were themselves surprised at how well it worked and functioned practically.