Challenger 2 Off Road Performance

[hatakashi]

Another question

Which is the first production tank fitted with Chobbam Armour? M1 or CR1?

[Damian]

From what I know, in M1's with T.U.S.K.-II kit driver have special seat thar absorbs underbelly explosions (probably T.U.S.K.-I also have now this seat's), for T.U.S.K.-III there are works on designing special seats for all crew members, I suppose that like many T.U.S.K. elements, these seats will become standard equipment.

 

Besides good ilm the things lector says are pure propaganda.

 

Which is the first production tank fitted with Chobbam Armour? M1 or CR1?

 

M1 was first mass produced IIIrd. Gen. tank with Burlington armor, FV4030 Challenger 1 was second because fielded later, besides this it was not the most powerfull NATO tank... well maybe, until 1987 when M1A1HA was fielded.

Edited August 18, 2009 by Damian

[johnr]

I seem to remember reading that the during trials of Leo1's and Chieftan in the mid to late 60's (possibly by the Isreali Army), that although the Leo's had higher road speed, horsepower and power to weight ration, that the Chieftan, the Chieftan's Hortsmann suspension worked better over rough ground and allowed the crew to tolerate a higher cross country speed.

 

I never really appreciated the significance of "ride" until I went on a Jeep Safari in Malta a few years ago, at the end of the tour I felt like my kidneys were up in the back of my neck and my stomach and liver had changed places.

[Damian]

Chieftain 900. :-)

 

But if it really was equiped with real Burlington? Most of construction was made from alluminium + ceramics right? Well I really don't want to see this tank burning. ;-)

[commander]

Chieftain 900. :-)

 

But if it really was equiped with real Burlington? Most of construction was made from alluminium + ceramics right? Well I really don't want to see this tank burning. ;-)

 

 

Nice one Stu however 900 was as said vismod out of sheet steel to represent to the customer what their Chieftain would look like with Chobham. In which case if the deal had not fallen through the first Production tnak with chobham may well have been a far east customer. It also had CV12 power pack and hydrostrut suspension, and did go rather well.

[AlexW]

Are the tank crew members belted to their seats in a modern tank?

Challenger 2 has seat belts/restraints for each crewmember.

[Damian]

Damn guy's, I think about FV4211 and talk about Chieftaine 900. ;-)

 

Yeah, FV4211 have early Burlington armor, and I saw some pics of that beast, but I never saw any pics of Chieftaine 900, somebody have those? Please post them. :-)

 

Challenger 2 has seat belts/restraints for each crewmember.

Great thing but... in combat there is possibility that these belts jam, so what then? When crew must bail out?

 

Heh I must be more carefull, this certain lead's to "Death Before Dismount" ideology.

 

US Burlington was with the DU array

 

Ehm no, not really, Burlington is Burlington, British design adopted by US, US in 1987 fielded M1A1HA with new armor based on Burlington but very different I suppose, in other case this was 1st. Gen. of this new US armor, 2nd. Gen. was fielded in 90's and 3rd. Gen. in XXI.

 

Hmmm, my thoughts are these, 1st. gen was indeed a Burlington more advanced derivative, 2nd. gen. have less common design, probably different structure, materials and 3rd. gen. we can call a US counterpart (I mean similarities in how armor works, maybe used materials etc.) of British Dorchester armor (I think Paul Lakowsky mention this in his Armor Basics).

 

Well, this is how a I see this. :-)

Edited August 18, 2009 by Damian

[Tomas Hoting]

Challenger 2 has seat belts/restraints for each crewmember.

 

I would think that a simple lap belt is or should be some sort of standard today. The increased interest in mine protection has led to the adoption of full safety harnesses in some modern armoured vehicles. The troop seats in the infantry compartment of the Italian VBM Freccia and German Puma IFVs or the Australian Bushmaster IMV MRAP for example have them.

[johnr]

I just remember, the episode of Top Gear show recently were Jeremy Clarkson was chased by a Jackal, Panther, Mastiff, Trojan and Titan, one of the soldiers stated that his vehicle; presumably the Trojan or Titan, had 1500hp. I was under the impression the all the Chally 2 based vehicles had the 1200hp engine. Has the more powerful engine been fitted to the Trojan and Titan, or is it just a case of a squaddie "talking up" a vehicle.

 

For those of you who didn't see the piece:

 

http://www.youtube.com/watch?v=vJWsWGiI57A

[Tomas Hoting]

I just remember, the episode of Top Gear show recently were Jeremy Clarkson was chased by a Jackal, Panther, Mastiff, Trojan and Titan, one of the soldiers stated that his vehicle; presumably the Trojan or Titan, had 1500hp. I was under the impression the all the Chally 2 based vehicles had the 1200hp engine. Has the more powerful engine been fitted to the Trojan and Titan, or is it just a case of a squaddie "talking up" a vehicle.

 

For those of you who didn't see the piece:

 

http://www.youtube.com/watch?v=vJWsWGiI57A

 

Same engine (Perkins CV12), but a modified gearbox and cooling system.

[Delta tank 6]

There is some good footage on here of the Hydrogas suspension at work. Bear in mind this is Challenger1 with the narrower one piece tracks. From some figures posted up ages ago, the wider 'Leopard2' style tracks would to have reduced ground pressure on Challenger2.

 

Also bear in mind, I think many people were surprised at the relatively unspritely performance exhibited by the tanks in 2003 on various bits of film footage. It turned out later they were running them on Helicopter fuel from a nearby USMC pipeline (JP7?) which reduced the performance.

 

Stuart,

 

As I understand it every vehicle now runs on JP8 (?). When I was on M-1s way back in the early 80s (1982-1985), we would put some JP4 (helicopter fuel at that time aka as jet fuel) in our tanks in the winter to prevent the diesel fuel from getting thick. We were told that this would increase our horse power and they also told us not to use the smoke generators !

 

Mike

[commander]

As requested pic of chieftain 900 (Centaur) as you can see it radically changes the shape, centaur fcs is very prominent though.

 

 

 

Stu no the hull is still sat there, the turret was fitted to Chieftain 2000 which on last check was up for sale at Withams

 

[AlexW]

..one of the soldiers stated that his vehicle; presumably the Trojan or Titan, had 1500hp. I was under the impression the all the Chally 2 based vehicles had the 1200hp engine. Has the more powerful engine been fitted to the Trojan and Titan, or is it just a case of a squaddie "talking up" a vehicle.

The latter I'm afriad. Titan and Trojan both have 1200hp from a CV12 which is only very slightly different to the model in CR2.

[Special-K]

Stuart,

 

As I understand it every vehicle now runs on JP8 (?). When I was on M-1s way back in the early 80s (1982-1985), we would put some JP4 (helicopter fuel at that time aka as jet fuel) in our tanks in the winter to prevent the diesel fuel from getting thick. We were told that this would increase our horse power and they also told us not to use the smoke generators !

 

Mike

 

 

 

 

Yeah, I remember reading that British crews were also told not to use smoke generators, though I cant help but think there were a few occasions when using them would have proven very useful. It may well have been JP8, I had copied the account down somewhere but have now lost it, but I do recall running it through the CV12 did reduce the amount of power available. It presumably has the reverse effect in a gas turbine, though would it increase rate of wear?

 

Thanks Bob, I really must look through that Withams site again.

 

 

 

As I understand it every vehicle in the US Army (maybe the US military as a whole) uses JP-8 instead of diesel. The reason for this is it behaves more predictably in cold and very hot weather than standard diesel. A side effect of this is that using the smoke generators will cause it to start on fire rather than just smoke. JP-8 also reduces power meaning that fuel economy and unrefueled range goes down a bit, though I guess this is made up for by the ease of logistics.

 

Another thing I have read, though I don't know if this is accurate, is that the switch over from diesel to JP-8 caused a number of problems for the vehicle. AIUI, use of diesel causes deposits to build up in the engine - which is normal and not a problem. When they switched to JP-8 it caused the deposits to come loose which created all sorts of issues with the engines. I read a book about M1 tanks in ODS that mentioned this and how the M1's were going through engines at a crazy rate until they got brand new M1A1's and the problems went away.

 

 

 

 

 

-K

[DKTanker]

I read a book about M1 tanks in ODS that mentioned this and how the M1's were going through engines at a crazy rate until they got brand new M1A1's and the problems went away.

-K

There were only, I believe, two battalions of M1s in theater, and they belonged to 1ID. That would make them the oldest tanks in theater and they kept their M1s throughout the operation. The next oldest tanks in theater belonged to 1AD and 3ACR, all of which were from the first years production of M1A1s. I can't speak for 3ACR, but I can for having one of the oldest tanks in 1AD, and I can't recall any abnormality associated with changing from DF2 to JP8, aside from the smoke generator prohibition.

 

I was referencing the older tanks because there was always the chance that the fuel injector nozzle would coke up over time no matter what fuel was used. Point in fact, it wasn't uncommon to replace fuel nozzles when the tanks were new*. But other than the fuel nozzles there isn't much else that can go wrong internally aside from bearings and the occasional hole being burned through on and in the recuperator.

 

*I wouldn't be surprised to learn that a fuel nozzle would become coked up because of aborted engine starts or unexpected shutdowns. Both situations can occur independent of the fuel nozzle.

[Delta tank 6]

As I understand it every vehicle in the US Army (maybe the US military as a whole) uses JP-8 instead of diesel. The reason for this is it behaves more predictably in cold and very hot weather than standard diesel. A side effect of this is that using the smoke generators will cause it to start on fire rather than just smoke. JP-8 also reduces power meaning that fuel economy and unrefueled range goes down a bit, though I guess this is made up for by the ease of logistics.

 

Another thing I have read, though I don't know if this is accurate, is that the switch over from diesel to JP-8 caused a number of problems for the vehicle. AIUI, use of diesel causes deposits to build up in the engine - which is normal and not a problem. When they switched to JP-8 it caused the deposits to come loose which created all sorts of issues with the engines. I read a book about M1 tanks in ODS that mentioned this and how the M1's were going through engines at a crazy rate until they got brand new M1A1's and the problems went away.

-K

 

I did not know about the fuel predictability issues. I always thought that they did it to solve the logistics issues. One fuel is better than three (MOGAS, DF-2, and JP-8). The beauty of a turbine engine is that it will burn anything that can burn, unfortunately it burns a lot of fuel.

 

Mike

[johnr]

Wasn't there some controversy a while back about using JP8 in American AFV's causing some of the catastophic fires? I seem to remember a case were a number of soldiers died when trapped in their Bradley after being hit, the cause was felt to be the volatility of the JP8?

[AdmiralB]

But other than the fuel nozzles there isn't much else that can go wrong internally aside from bearings and the occasional hole being burned through on and in the recuperator.

 

I agree, there's no place in a turbine for deposits to form.

[Stephan]

Just to get all these fuel issues straight:

 

Diesel actually is rather a blend of different distillate fractions from the middle distillate, in contrast to gasoline or kerosene. More specifically, diesel is a mix of kerosene and light, medium and heavy fuel oil. The exact composition can vary from lot to lot, depending on the raw oil composition and availability of the different fractions due to market fluctuations. The kerosene content is increased during the winter season to lower the cloud point.

Before 1996 (in the EU, IIRC 2006 in the US), the quality of diesel was not well controlled, due to very wide specifications - especially in the US. This bad quality was one of the considerations for the US to switch to the much better specified JP-8/ F-34 (one obviously more important one being logistics), which was available cheaper than high quality diesel.*

 

The various JPs are based on the civilian jet fuels with various additives to achieve specific military requirements. E.g. the base for JP-8/ F-34 is Jet-A1/ JP-1A/ F-35, with the additives S-1745 (Fuel System Icing Inhibitor), S-1747 (Corrosion Inhibitor/ Lubricity Improver), a static dissipator and antioxidants.

JP-4 was based on Jet-B, a wide cut fuel with a high gasoline content.

JP-5/ F-44 is a high flashpoint safety fuel for naval (aviation) applications.

JP-6 was an XB-70 specific developement, an improvement on JP-5 with e.g. a decreased freezing point.

JP-7 was (is?) a high supersonic fuel, specifically for the SR-71, with improved thermal stability and increased flashpoint.

 

Coming back to JP-8, there are several complications when using it for land applications. Many will have heard of the reduced flashpoint compared to diesel (38°C to 56°C) and the reduced specific energy compared to diesel (~10%, so, using kerosene, or increasing the kerosene content in diesel will reduce power, not increase it). Additionally, as has been mentioned, kerosene can solve diesel deposits in the fuel system. This will also affect turbine engines that previously ran on diesel for a longer time. The solved deposits will clog the fuel filter. For a while after switching from diesel to kerosene, the fuel filter should be cleaned with petroleum F-58 to prevent problems.

The biggest issue of JP-8 comes with modern diesel engines. The Cetan number of JP-8 is about 10-20% lower than that for diesel, which leads to problems with high compression engines, the comparatively low lubricity of JP-8 is a problem with common-rail injection systems. Thus a multi functional additive (S-1750) needs to be added to JP-8/ F-34 to create F-63, however, F-63 shall not be used in (aircraft) turbine engines, which makes the single fuel concept a bit questionable.

 

 

 

 

* E.g. for Germany, the situation was quite the opposite. Just when JP-8 was finally specified and available NATO-wide, closely specified, high qualitiy diesel became the norm on the civilian market and thus was available cheaply, so the Bundeswehr choose to keep diesel F-54 as the standard fuel for peace operations in Germany (another consideration was the introduction of more modern engines with the above mentioned complications).

Edited August 19, 2009 by Stephan

[Delta tank 6]

Just to get all these fuel issues straight:

 

Diesel actually is rather a blend of different distillate fractions from the middle distillate, in contrast to gasoline or kerosene. More specifically, diesel is a mix of kerosene and light, medium and heavy fuel oil. The exact composition can vary from lot to lot, depending on the raw oil composition and availability of the different fractions due to market fluctuations. The kerosene content is increased during the winter season to lower the cloud point.

Before 1996 (in the EU, IIRC 2006 in the US), the quality of diesel was not well controlled, due to very wide specifications - especially in the US. This bad quality was one of the considerations for the US to switch to the much better specified JP-8/ F-34 (one obviously more important one being logistics), which was available cheaper than high quality diesel.*

 

The various JPs are based on the civilian jet fuels with various additives to achieve specific military requirements. E.g. the base for JP-8/ F-34 is Jet-A1/ JP-1A/ F-35, with the additives S-1745 (Fuel System Icing Inhibitor), S-1747 (Corrosion Inhibitor/ Lubricity Improver), a static dissipator and antioxidants.

JP-4 was based on Jet-B, a wide cut fuel with a high gasoline content.

JP-5/ F-44 is a high flashpoint safety fuel for naval (aviation) applications.

JP-6 was an XB-70 specific developement, an improvement on JP-5 with e.g. a decreased freezing point.

JP-7 was (is?) a high supersonic fuel, specifically for the SR-71, with improved thermal stability and increased flashpoint.

 

Coming back to JP-8, there are several complications when using it for land applications. Many will have heard of the reduced flashpoint compared to diesel (38°C to 56°C) and the reduced specific energy compared to diesel (~10%, so, using kerosene, or increasing the kerosene content in diesel will reduce power, not increase it). Additionally, as has been mentioned, kerosene can solve diesel deposits in the fuel system. This will also affect turbine engines that previously ran on diesel for a longer time. The solved deposits will clog the fuel filter. For a while after switching from diesel to kerosene, the fuel filter should be cleaned with petroleum F-58 to prevent problems.

The biggest issue of JP-8 comes with modern diesel engines. The Cetan number of JP-8 is about 10-20% lower than that for diesel, which leads to problems with high compression engines, the comparatively low lubricity of JP-8 is a problem with common-rail injection systems. Thus a multi functional additive (S-1750) needs to be added to JP-8/ F-34 to create F-63, however, F-63 shall not be used in (aircraft) turbine engines, which makes the single fuel concept a bit questionable.

* E.g. for Germany, the situation was quite the opposite. Just when JP-8 was finally specified and available NATO-wide, closely specified, high qualitiy diesel became the norm on the civilian market and thus was available cheaply, so the Bundeswehr choose to keep diesel F-54 as the standard fuel for peace operations in Germany (another consideration was the introduction of more modern engines with the above mentioned complications).

 

Obviously you work in this industry or you have waaay too much time on your hands!!

 

Mike

[Fritz]

Damian,

 

Not only may it reduce life time of engine, suspension, transmission, tracks, etc. DON'T FORGET THE LIFE OF THE CREW!! :-) The M-1 is fast enough and when I was 25 years old or so, I told my driver to slow down!! I though we were all going to die! 60+ tons going downhill on a German two line highway, so fast that my driver was afraid to turn his head to the left to look at the speedometer and tell me the speed!! Ouch!

 

Mike

 

Pardon the silly question, but do M-1s (and other tanks) have horns?...

[D Simcock]

Does anyone have realistic comparisons of mobility between Challenger 2's and Merkavas, M1's, Leopard 2's, the T series, LeClerc etc?

Presumably there is a some trials data from the Greek tank competition of the 1990's, the Saudi competition between the Abrams and Challenger 2. Challenger 2's have been on active deployment alongside Leopard 2's (Kosovo) and M1A1's (Iraq 2003) now, so there must be a bit of anecodotal evidence out there.

 

Is hydrogas suspension better than torsion bar on an MBT or not? Hydrogas costs more doesn't it?

 

Within the British Army, how does Challenger 2 compare in cross country performsance the Warrior?

[Stephan]

Pardon the silly question, but do M-1s (and other tanks) have horns?...

 

At least for german vehicles, the german road vehicle licensing regulations require that a vehicle has a horn. So, yes, the Leopard 2 and all other german made armored vehicles do have a horn. I would not be surprised if it was the same for most other countries.

[DKTanker]

At least for german vehicles, the german road vehicle licensing regulations require that a vehicle has a horn. So, yes, the Leopard 2 and all other german made armored vehicles do have a horn. I would not be surprised if it was the same for most other countries.

USAREUR didn't have horns on tactical tracked vehicles while in Germany...didn't have rear view mirrors either.

[johnr]

At least for german vehicles, the german road vehicle licensing regulations require that a vehicle has a horn. So, yes, the Leopard 2 and all other german made armored vehicles do have a horn. I would not be surprised if it was the same for most other countries.

 

I seem to recall BAOR Chieftans having flashing "police" lights having to be fitted if transiting by road.