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Comment by protomyth | Hacker News Reader

"The L-ATV can be transported by heavy-lift helicopter or by the Marine Corps' landing craft, but it's a much bigger payload than the Hummer, with a curb weight nearly three times that of the older vehicle: about 14,000 pounds, compared to the Humvee's 5,900 pounds."

and

"But the L-ATV also has better fuel efficiency than the Humvee, and its suspension system allows for 70 percent faster off-road speeds."

What the heck?!? It weighs almost 3x as much but gets better gas mileage?

Glad they are buying something that deals well with IEDs.

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Nitpicking about the OP but 14,000 / 5,900 is nearer to 2x than it is to 3x.

I believe it's a hybrid. My company makes fuel tanks for the current M-ATV from Oshkosh. Working on bids to make the tanks for this one too.

There's a diesel-electric transmission option[0], but I'm not sure there's much capacity for battery-only operation so calling it a hybrid is a stretch. It allows the ATV to double as a hefty generator (120kW AC) for field ops which is pretty cool.

[0] http://oshkoshdefense.com/components/propulse/

The wiki directly states that the "hybrid" engine accounts for a 35% increase in efficiency.

Does it need to be able to run in all electric to be considered a hybrid?

https://en.wikipedia.org/wiki/Oshkosh_L-ATV

> Does it need to be able to run in all electric to be considered a hybrid?

Well I'd say so, using multiple power sources is what makes a hybrid vehicle hybrid. If it must always use the ICE, it just has an electric transmission rather than a mechanical one.

> If it must always use the ICE, it just has an electric transmission rather than a mechanical one.

I would respectfully disagree. When an engine is asked for WOT most of the time they throw fuel economy to the wind and give it max power bar none. You might spend 50% more fuel for 10% more power versus 90% throttle.

If you have a 3kWh battery bank then you can eliminate this really wasteful special case and use the batteries as very, very short term power source to get the vehicle up to speed quickly. 3kWh discharged in 3 minutes is 60kW which is an extra 50-75HP depending on your driveline efficiency. And then when you're not flooring it you can run the engine a bit harder and quickly recharge the battery bank for the next surge.

Just because you're not running off of batteries for an hour doesn't make it not a hybrid. If you use the batteries for even just 10-15 seconds in particularly fuel-wasteful engine conditions to eliminate them, that totally qualifies as hybrid.

> Just because you're not running off of batteries for an hour doesn't make it not a hybrid. If you use the batteries for even just 10-15 seconds in particularly fuel-wasteful engine conditions to eliminate them, that totally qualifies as hybrid.

That means any KERS or regenerative braking[0] qualifies the machine it's a component of as a hybrid, it completely devaluates the word and makes it entirely meaningless.

[0] unless it stores back in the same place?

If you have regenerative braking most of the time that's electric, so you've got a motor/generator and some kind of energy storage. To me hybrid means that you have a gas/electric hybrid drivetrain not that it runs off of batteries for an amount of time that you feel is long enough.

Good regenerative brakes probably have to be at least 50-100HP otherwise they don't offer very much braking effect. And that would mean that they can offer a substantial boost during acceleration too. And that can substantially alter the fuel economy of a vehicle.

Since you don't like my definition of hybrid, and you think it devalues the word (despite being completely in line with the Wikipedia definition) why don't you at least offer your definition. This isn't a conversation at the moment, just you shitting on things that you don't like and complaining.

https://en.wikipedia.org/wiki/Hybrid_vehicle

> If you have regenerative braking most of the time that's electric

That's just a confirmation of my footnote not an answer to my question. Is an F1 with KERS or a truck with hydraulic regenerative braking a hybrid?

> not that it runs off of batteries for an amount of time that you feel is long enough.

That I agree with actually.

> Since you don't like my definition of hybrid, and you think it devalues the word (despite being completely in line with the Wikipedia definition) why don't you at least offer your definition.

That it can use its power sources independently.

> That it can use its power sources independently.

I would suspect that all hybrids can use their power sources independently, to some degree. But is that degree useful.

What you're calling a "hybrid" is really more of a "dual fuel" vehicle, not a hybrid. Because in your mind, if it can't run completely 100% off of EITHER power source at any one time, it's not a hybrid. But that's not how most of the world defines hybrid.

I'm an automotive engineer, if a system can recover kinetic energy and use it for propulsion, we call it a hybrid. KERS is absolutely a hybrid system, they are just optimized for power instead of energy.

The real pedantic question is does predictive cruise control count as a momentum hybrid.

> What the heck?!? It weighs almost 3x as much but gets better gas mileage?

More modern engine and better transmission probably?

Yes, annd the USArmy invested in 2010 on multi-million dollar fuel efficiency testing center. Starting around 2008 there was a big internal push to make military vehicles more fuel efficient.

I highly doubt the new engine. Most USArmy engines are very old (typically 60's era Diesel) due to the object simplicity (and fuel diversity) [1]. Anyone Joe-Blow can be trained to fix these, and fixes are faster under fire.

Most the fuel savings from from transmissions/cooling systems. Which are modular so they can be upgraded, and simply replaced on failure.

Source: Contracted to TARDEC research 2010-2013

[1] I'm wrong here. L-ATV uses a Duramax V8 circa 99-01 GM engine. Which is ~30 years newer then other engines used.

Talk about too little, too late. The largest consumption of fuel in the middle east wars was ... for air-conditioning tents(!) Vehicles come in far behind.

Vehicle is still a good thing, large on-base generators are easier to resupply than vehicles out in the field.

>Talk about too little, too late.

Learning a lession and implementing a fix within ~5 years of that issue being raised is fairly quick for the USGov all things considered.

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