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US Army Unveils Hybrid-Electric Propulsion System
Gary writes to mention that the U.S. Army recently unveiled a new hybrid-electric propulsion system for use in a new line of manned ground vehicles (MGVs). The new line will have eight different variants, all using the same chassis. The unique feature of the new MGVs is that the traditional engine has been decoupled from the drive train and is used only to recharge the battery and power other systems within the vehicle.
"The most unique feature of the new MGVs is that the traditional engine has been decoupled from the drive train and is used only to recharge the battery and power other systems within the vehicle."
Gee. Kind of like a Diesel Train.
-b.
This is especially true since the current big US tank (M1 Abrams) is turbine powered, which causes really awful fuel consumption at idle and low speeds. If the turbine could run at its optimum speed, it would improve consumption significantly.
Also, being able to turn off the turbine and creep forward would reduce the infrared signature of the vehicle, adding yet another "stealth" aspect.
-b.
Yes, of course because all series hybrid vehicles are similar. (omg)
e p-vehicles-receive-votes-of-confidence-from-sweden -bae-02446/
The Swedish SEP ran for the British FRES program:p e/fres.htm
And by the way the US Army is not the first with that idea:
http://www.army-technology.com/projects/sep/
http://www.defense-update.com/products/s/sep.htm
http://www.defenseindustrydaily.com/hybriddrive-s
http://www.globalsecurity.org/military/world/euro
Unfortunately, recently it was excluded due to (perceived?) lower maturity of the technology than the competitions offers.
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The Volkswagon was not initially a military vehicle. It was designed by Ferdinand Porsche (at Hitlers request) as a car even factory workers could afford. This was slightly before WWII. During the war, they produced military variants, but the original design was for what it once again became afterwards: a super-inexpensive civilian car.
As far as your larger point, the military has always been in the vehicle design business. Jeep, Hummer, etc.
I agree with you in that there is no need for complex gearboxes.
;-)
But your reply sounds like you consider a planetary gearbox to be simplier than a countershaft gearbox...
And by the way: every gearbox is modulating speed and torque of the shafts with respect to each other. You multiply the one with a certain factor and divide the other by the same factor. That's the way it works.
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They ARE simpler -- not necessarily to build, but to control. Everything is done with wet clutches or brake bands, so there's no real chance of breaking off engagement dogs or gear teeth.
Notice that almost all automatic transmissions before about 1995 used planetary gearsets, not a countershaft system. Good automated countershaft boxes like BMW's SMG and the VW DSG are comparatively recent developments.
Of course, an electric motor makes things somewhat easier, since the armature might be light enough not to require a clutch (just cut power to the thing), but planetary boxes still are best for that sort of application.
-b.
M1 Abrams tanks have a turbine engine that is hooked directly into a generator which powers a 1500 hp (1119 kW) electric motor
Let me set this straight.
Unless the Army has completely refitted it's tanks, the above is only partly true. It does have a turbine engine and does produce 1500hp, but it's not an electric motor. Has a plain old drive train that goes into the rear sprockets. There are no massive batteries to store the charge (IIRC it has 8 12v batteries).
What makes these things so darn quiet (for a tank, you hear the treads clanking before the engine when it's moving) is that the exhaust is directed up at about a 45 degree angle so the majority of the sound doesn't echo off anything. Of course, that gives it a massive thermal signature, but at the time of it's design, soviet block tanks were not using thermal sites.
This is speaking from experience, I spent 4 years as an M1A1 tank crew member (19k) and prepped the engine(power pack)for removal more than once. There is no greater rush than firing the 120mm main gun at a target 2100m away and/or moving 68 tons of combat steel over any terrain.
Hope this helps, I don't see any "green tanks" in the future and they get horrible gas mileage - a full tank of 504.4 gallons gives you about 200 miles over flat terrain @ 35mph.
Good judgment comes from experience, and a lot of that comes from bad judgment.
The use of all-electric drive can provide some interesting opportunities for advanced systems such as traction control. By placing multiple, smaller drive motors at each wheel, power can be directed optimally for terrain conditions. No complex mechanical equipment is needed as the algorithms can be implemented completely in software.
The other advantage can be the ability to optimize the IC engine for changes in the fuel available without screwing around with the entire drivetrain. Heck, they can make the IC portion modular and, if the economics of fuel sources change, just pop in the appropriate engine.
Have gnu, will travel.
This refers to the UD effort that predates FCS by many years:
l
/ humvee.html
http://www.angelfire.com/art/enchanter/hybrid.htm
Ralph Zumbro, Author of "Tank Sergeant", writes about the Hybrid drive M113 that United Defence have built:-
"Phil, The one I was in, and it may be the only one, is state of the art. They steer it with a Bradley gunner's control and it will run for an hour at 30mph on two batteries which are in boxes sized approximately 18"x36"x48". Then a standard issue genset cuts in. The motors are rated at 250 hp each and are oil cooled. It is weird to see a 3 inch diameter drive shaft coming out of a motor the size of a 5 gallon can.
The rubber tracks are soundless, and they've got 2500 miles on them with very little wear showing. That adds up to a VERY quiet vehicle for recon work. Put electric motors, rubber tracks and a two man turret with a 30mm gatling weapon on a standard 113 hull and you've got a recon Tankita.
I mentioned to the people at United Defense that not needing air for the engine made the vehicle capable of running around UNDER water and was told that that had been thought of. That means that you could add enough armor to stop larger weapons, as long as you don't compromise the mobility."
More links:
http://www.defensetech.org/archives/002338.html
Hybrid M113
http://www.youtube.com/watch?v=RbWbkOkTydk
Hybrid HMMWV
http://www.evworld.com/archives/conferences/evs14
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
As gas stays above $3.00 a gallon, people, and businesses and organizations and governments who don't give a rats ass about the environment are going to start looking around at ways to save or make money.
/US gallon in my local station. People are still filling up their cars and 4x4 SUVs are still fashionable, it's a disease we've caught from over the pond (I mean, in the mountains and rural areas yes, they might be useful but to go to the supermarket in urban southern England? How many litres of engine do you need to bump up that 4 inch curb on the side of the road?).
Glad you're not a complete libertarian on this, I'm completely with you. Round where I live (in the UK) petrol (gas) is 7.20 dollars
I think you're going to need some government intervention on this. People are very happy to keep driving tanks round small urban roads at 7 dollars a gallon. Other solutions more than welcomed, but just saying, don't believe there's some mythical point at 4 or 5 dollars a gallon when 'the people' will all discard their big autos and jump on public transport and bicycles...
I don't know if there are other commonly used materials for tank shells - steel or something?
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
EMP is primarily damaging to electronics and very long runs of power cables. If both coupled and uncoupled vehicles rely on un-EMP hardened control electronics then both are vulnerable. Contrary to Hollywood, small generators and batteries aren't all that vulnerable.
You are gravely mistaken. Countershaft transmission have been around for a long time, actually longer than planetary gearboxes. They are the typical gear box as invented before Christ. You confuse the recent development of double-clutch transmissions with countershaft technology. I design these things, I know. :-)
Anyway, also in countershaft boxes the gear-pairs can be in constant engagement, what you use is a sort of spline or wet disc couplings to connect them to the torque-carrying shaft. No need to move the actual gear wheels.
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Yes, I'm left. You have a problem with that?