Cuestion about the Leclerc's Hyperbar engine

[ramontxo]

I have just read in another topic that it has an integrated gas turbine. From wilkypedia : "The "hyperbar" system integrates a Turbomeca TM 307B gas turbine in the engine, acting both as a turbocharger and an APU giving auxiliary power to all systems when the main engine is shut down. The Hyperbar name comes from the unusually high boost pressure of 7.5 bar and the resulting mean effective pressure of 32.1 bar" This seems to be just the opposite arrangement to that found in S-tank with the gas turbine as main engine an an auxiliary diesel. What advantages (if any) has the Hypèrbar option? The same article mentions early reliability problems. Have they disappeared? Also i would welcome any graphics. As always thanks in advance

[Ssnake]

The main advantage of the Hyperbar engine seems to be the comparatively high power density of the diesel engine (in other words, a much smaller volume for the same nominal power output). The Leclerc has about the same combat mass as a Leo 2A4, but one pair of roadwheels less as the hull could be made one meter shorter than the Leo 2. Significant disadvantages are

1) the about doubled fuel consumption in comparison to a conventional turbo diesel (in the Swedish tank trials 1994 it was 720 liters/100km for the Leo 2, 1380 l/100km for the Leclerc, and 1478 l/100km for the Abrams), and

2) the narrower RPM band where the engine can be operated with near-optimal torque

 

Last but not least the Leclerc has a higher ground pressure than the Leo 2, due to the shortened hull. It may be an acceptable trade-off depending on one's preferences, but it's something to keep in mind. Of course the engine volume reduction could also have been used for more crew space, or additional fuel or ammo storage, so it's not an inherent disadvantage of the hyperbar engine.

[ramontxo]

The main advantage of the Hyperbar engine seems to be the comparatively high power density of the diesel engine (in other words, a much smaller volume for the same nominal power output). The Leclerc has about the same combat mass as a Leo 2A4, but one pair of roadwheels less as the hull could be made one meter shorter than the Leo 2. Significant disadvantages are

1) the about doubled fuel consumption in comparison to a conventional turbo diesel (in the Swedish tank trials 1994 it was 720 liters/100km for the Leo 2, 1380 l/100km for the Leclerc, and 1478 l/100km for the Abrams), and

2) the narrower RPM band where the engine can be operated with near-optimal torque

 

 

Thanks very much. How does it compare with with the diesel Euro pack integrated in the export Lecrercs?. By the way how they fitted it in a so limited space?

 

Have edited it after realising that the first cuestion was alredy answered in the Ssnake post, so sorry my (feeble) excuse being that i was in a hurry...

Edited November 12, 2011 by ramontxo

[istvan47]

The main advantage of the Hyperbar engine seems to be the comparatively high power density of the diesel engine (in other words, a much smaller volume for the same nominal power output). The Leclerc has about the same combat mass as a Leo 2A4, but one pair of roadwheels less as the hull could be made one meter shorter than the Leo 2. Significant disadvantages are

1) the about doubled fuel consumption in comparison to a conventional turbo diesel (in the Swedish tank trials 1994 it was 720 liters/100km for the Leo 2, 1380 l/100km for the Leclerc, and 1478 l/100km for the Abrams), and

2) the narrower RPM band where the engine can be operated with near-optimal torque

 

Last but not least the Leclerc has a higher ground pressure than the Leo 2, due to the shortened hull. It may be an acceptable trade-off depending on one's preferences, but it's something to keep in mind. Of course the engine volume reduction could also have been used for more crew space, or additional fuel or ammo storage, so it's not an inherent disadvantage of the hyperbar engine.

 

Excellent post, thank you. I read already 20 years ago that Leclerc'engine was thristy, but i did not imaged that it was so thirsty.

M1 had a more than double fuel cons. than the Leopard 1, very interesting indeed. Those are scary data's since the M1 is supposed to have +450 km endurance, but with 14,78 l/km the 1,900 reserve translates in just 120 km or so. I read datas even worse in the Pentagon' rapport about DS. It was even claimed to surpass 16 l/km.

Another interesting point, Challenger in DS had a fuel cons about 1/3 of the M1's. Modern tanks may be a powerful beasts, but really the fuel consumption in a 'real life' experience is scary.

M-47 seemed thirsty just because consumed 1 l/every 125 meters (8 l/km). Leopard 1 was particularly efficient in that sense, even if the 650 km range was only in a street endurance journey.

Just to compare some datas i remember about the tank's consumption.

[Tomas Hoting]

Another advantage of the Hyperbar engine is the fact that the integrated gas turbine (whose exhaust gases are used to drive the hybrid turbocharger) can also run as an APU with the main diesel switched off, and it also provides good cold starting characteristics. The very high fuel consumption which became apparent during the trials in Sweden in the early 1990s was later (apparently) reduced by lowering the idling RPM.

 

The Leclerc Tropicalisé sold to the UAE has the EuroPowerPack (MTU diesel and Renk transmission) instead of the Hyperbar engine and SESM transmission. The tank however doesn't have an integrated APU like the French army model, but one mounted in a detachable armoured box at the rear right hull (like the early APU in the M1 Abrams).

[Ssnake]

Excellent post, thank you. I read already 20 years ago that Leclerc'engine was thristy, but i did not imaged that it was so thirsty.

M1 had a more than double fuel cons. than the Leopard 1, very interesting indeed. Those are scary data's since the M1 is supposed to have +450 km endurance, but with 14,78 l/km the 1,900 reserve translates in just 120 km or so. I read datas even worse in the Pentagon' rapport about DS. It was even claimed to surpass 16 l/km.

 

Much depends on the actual mission profile, mind you. These are just the results of approximately 3,000km driving in the Swedish trials, and an unknown amount of idling. The more you drive and the less you idle the engine, the closer will the actual consumption figures be. It's probably justified to suspect that the Swedish trials are closer to a realistic mission profile than synthetic tests of driving range or whatnot. Also, I think that the M1 for Sweden didn't have an APU.

The fuel consumption under load aren't that dramatically different. It's the idling times where the conventional diesel has the biggest advantages in consumption.

[Ssnake]

Thanks very much. How does it compare with with the diesel Euro pack integrated in the export Leclercs?

In what respect?

The MTU Euro-Powerpack already uses about half the volume of the old Leo 2 engine; in comparison to the latter, the Hyperbar engine needs about a third of the volume IIRC. So one of the most modern diesel engines has a volume disadvantage of 165% volume demand (instead of 300%; my rough calculation was 0.55 : 0.333. I'd need to look up the exact figures in the Rolf Hilmes book, but I'm too lazy right now).

[DKTanker]

The fuel consumption under load aren't that dramatically different. It's the idling times where the conventional diesel has the biggest advantages in consumption.

Indeed. For instance those that look merely at the raw fuel consumption by US forces during ODS and then point out how bad it was, neglect to understand just how much not moving but engine operating was going on. Moreover, especially for the 7th US Corps, even when moving, the movement was rather pedestrian and well below optimum speed for fuel efficiency. None of that is to say the M1 isn't thirsty, it is, but the operational tempo of ODS made it seem as if they were less efficient than they really were.

[Olof Larsson]

This seems to be just the opposite arrangement to that found in S-tank with the gas turbine as main engine an an auxiliary diesel.

 

It would be more correct to call the piston engine in the S-tank the primary engine

and the gas turbine as a boost engine.

In real life, the piston engines proved to weak, so the gas turbina had to provide power ever during road marsch.

 

The CODAG-arrangement had advantages in cold weather compared to a pure piston engine solution

and that was that the gas turbine (what was wasy to start even if cold)

could be used to start the piston engine.

 

IMHO a pure diesel solution would have been better, but it would probably

be impossible to get enough hp from only diesels in the little space allocated in the front of the tank.

Perhaps with opposed pistons, but that would probably require to much work to maintain.

 

The very high fuel consumption which became apparent during the trials in Sweden in the early 1990s was later (apparently) reduced by lowering the idling RPM.

 

The general conclusion about the Leclerc in Sweden seems to have been that the Leclerc

concept wise was closest to what we wanted, but that the design was not ready for production.

 

So the engine might have been far from finished.

 

Furthermore the tanks came straight from desert trials,

and apparently suffered from being tweaked for that environment.

[Colin]

The problems with small engines with high horsepower is often latent heat buildup, it can be dealt with, but if not done properly it can cause serious problems and short engine life, we found that out with the air cooled Deutz diesels in our hovercraft.

[Tomas Hoting]

In what respect?

The MTU Euro-Powerpack already uses about half the volume of the old Leo 2 engine; in comparison to the latter, the Hyperbar engine needs about a third of the volume IIRC. So one of the most modern diesel engines has a volume disadvantage of 165% volume demand (instead of 300%; my rough calculation was 0.55 : 0.333. I'd need to look up the exact figures in the Rolf Hilmes book, but I'm too lazy right now).

 

There are two nice charts in his book: one compares the powerpacks of the Leo 2, the Leclerc and the Leclerc Tropicalisé, the other one compares just the diesel engines themselves.

 

According to the chart which compares the powerpacks, the EuroPowerPack of the Leclerc Tropicalisé has a total volume of 4,54m³ vs. 5m³ of the V8X engine / ESM500 transmission combo of the French army Leclerc. The EuroPowerPack weighs some 800kg more, which leads to a lower mass-to-power ratio of 4,7kg/kw vs. 3,91kg/kw , but to a higher power-to-volume ratio of 242kw/m³ vs. 220kw/m³. The dimensions of the EuroPowerPack made it possible to install it into the Leclerc Tropicalisé without a major hull redesign, but (as I already wrote) they couldn't find enough space for an internal APU.

 

The chart which compares the diesel engines themselves gives some very favourable numbers for the Perkins Condor CV12. The CV12 used in the comparison (rated at 1119kw) is quoted to have very small overall dimensions and therefore a very high power-to-volume ratio of 878 kw/m³ vs. 689kw/m³ of the MTU MT883 and 549kw/m³ of the SACM V8X 1500. Jane's quotes different, larger dimension for the CV12, but even when using these numbers it's still a very compact diesel, being a bit shorter, but also a bit higher and wider than the MT883.

 

Of course, the dimensions of the entire powerpack are something completely different, and we all know that the installation of the EuroPowerPack in the Challenger 2E freed up internal space and allowed the vehicle to carry almost 400l more fuel.

[istvan47]

Indeed. For instance those that look merely at the raw fuel consumption by US forces during ODS and then point out how bad it was, neglect to understand just how much not moving but engine operating was going on. Moreover, especially for the 7th US Corps, even when moving, the movement was rather pedestrian and well below optimum speed for fuel efficiency. None of that is to say the M1 isn't thirsty, it is, but the operational tempo of ODS made it seem as if they were less efficient than they really were.

 

There must be the reason because british (and later, soviets with T-80U and the 18 wK GTA-18A) put an APU Coventry Climax diesel (37 hp) in their Challenger 1, that in DS consumed overall 1/3 of the total needed by M1s. Atleast an APU should had been provided since the start, after all not every army has the logistics of US Army and this must be pointed especially for export. Giving this tool to the M1 modernization did a fuel cons reduction estimed in atleast 20%. I think M1A2 have the APU, at last.

[Damian]

I think M1A2 have the APU, at last.

 

APU was availabale for M1 series in the 1980's allready, and was mounted on some tanks but placement was not optimal, in 1990's it was relocated to the turret rear on M1A1's and M1A2's, M1A2SEP is using under armor APU.

 

Also it seems from the latest reports that GDLS plans to replace AGT-1500C with GD883 (licence manufactured MTU MB883 EuroPowerPack).

[istvan47]

APU was availabale for M1 series in the 1980's allready, and was mounted on some tanks but placement was not optimal, in 1990's it was relocated to the turret rear on M1A1's and M1A2's, M1A2SEP is using under armor APU.

 

Also it seems from the latest reports that GDLS plans to replace AGT-1500C with GD883 (licence manufactured MTU MB883 EuroPowerPack).

 

 

Never heard about this APU system before M1A2, atleast my sources never noticed it. Maybe it was a very rare installation then in the '80s?

 

Installing the APU in the rear turret was penalizing the ammo box?

 

What's 'under armour APU'? The previous was 'unarmoured' then?

[Damian]

Never heard about this APU system before M1A2, atleast my sources never noticed it.

 

This is normal for poor sources... go and buy Richard Hunnicutt books that can be called a true bible about US AFV's history of development, no offence but Your knowledge about US AFV's especially their history of development is close to none.

 

Maybe it was a very rare installation then in the '80s?

 

It was not very wide spread but also not rare, I saw a photos of whole units of M1's or M1IP's with these APU's mounted to the rear of hull (right side).

 

Installing the APU in the rear turret was penalizing the ammo box?

 

No, APU is installed on turret, outside vehicle in storage basket area, there is no interference in turret bustle ammunition magazines (besides this in 1990's turret magazines for M1A1's were redesigned so there were 18 rounds in each of two magazines, not 17 as in first M1A1's and M1A1HA's).

 

What's 'under armour APU'? The previous was 'unarmoured' then?

 

Previous ones were outside armor mounted, the new ones in M1A2SEP's are mounted under armor.

 

Really go and buy some books, oh You can use google translator and read my article about M1 series, I can send it to You via PM if You wish, it is not perfect however and will need update just when I will end my other projects.

[istvan47]

Well i never pretended to know everything, just asking.

 

Last questions:

 

1-since i did not found any APU reference in DS, not even in Pentagon reports, i'll then suppose that those gear wasn't widespread in 1991?

 

2-What kind of APU was, diesel? turbine?

 

i lack as well info if early T-80s had an APU, surely they needed one.

 

Where were you articles?

[Damian]

1-since i did not found any APU reference in DS, not even in Pentagon reports, i'll then suppose that those gear wasn't widespread in 1991?

 

Not widespread, not on M1A1's and M1A1HA's, only seen on some M1 and M1IP's.

 

2-What kind of APU was, diesel? turbine?

 

IRCC 1st type was Diesel, the turret mounted and under armor mounted are GT's.

 

i lack as well info if early T-80s had an APU, surely they needed one.

 

AFAIK early T-80's did not have APU's.

 

Where were you articles?

 

? You mean published? Currently not in any military magazine, I am still fresh in this, maybe in future they will be published somewhere, I will send You my first, about M1 via PM.