Challenger 2 feedback

[dejawolf]

I did note though on one thread that someone was quoting a length of 30mm or so for the L27/28/29. Also quoting a gun of 30 calibres, I think confused by the L("Land")30 designation. It is of course 55 calibres long (which more than offsets the minor rifling pressure loss when compared to the 30 calibre long smoothbore on Leo 2A4 and M1A1 IIRC?) and the penetrator goes the full length of the round, so about 650mm.

so you have

L28 penetrator with a length of 650mm mv of 1670m/s = 510mm p0 in SB.

compared to:

M829 penetrator with a length of 500mm mv 1670m/s = 600mm p0 in SB.

nothing to see here, move along...

Edited April 18, 2014 by dejawolf

[Volcano]

Maybe you mean M829(A0), that one is 600mm.

[hoggydog]

What I can say is that both are "high caliber" sources

I see what you did there

[Hedgehog]

I see what you did there

As Crusty would say:

rtxbM7-jAD0

[Blahrmor]

Just got the upgrade from a long time absence. Lots of new toys to play with (last update I had was before the T-72M1; CV9040s were the newest boys).

Anyway, with the Challenger 2:

Just playing Instant Action to get a feel of it, the conclusions I've drawn:

-the thermal sight works well enough. Hitting moving targets out to the ranges in IA is relatively easy, as long as SABOT is used of course. I rather the thermal sight to the daysight due to the much easier ability to spot targets, even if the crosshair is "floating". I don't notice much of a difference in my hit percentage compared to the old M1A1 and Leopard 2A4 I played so much with back in the day

-armor seems to be very good, as long as that terrible weak spot behind the driver isn't hit

-ammo (L27) seems to require more hits to knock out the T-80Us when hitting the front, but you can reengage pretty quickly, and they have little hope of getting through your turret with the BM-42 which they sling, so the duel is with the CR2. I've noticed that this is an accurate observation from playing several IA matches compared to the M1A2 and its ammo (woah with the thermal sight on that thing! What is it, 40 power? It's too easy). Other than the T-80Us, I don't notice any difference. The HEAT round is hard to hit with (HESH?) due to the sight jumping way up (or down); I haven't figured out how to work that on my own yet (no manual for me!)

I like it. Definitely competitive with the M1A1s and Leopard 2s; T-80Us and I'm guessing T-90Ss also, but with T-72M1s and less being the usual roving targets. M1A2 seems to be in a league of its own with that thermal sight it has.

Good job I must say.

[lavictoireestlavie]

What is up with this mystical new L28A2 round ? I heard a rumor that it is second only to the m829a3 and that the charm 3 really isnt being used anymore. Is this true ?

Also what are your thoughts on this "I think you will find that the L30A1 120MM rifled cannon has claimed the longest confirmed tank kill in the world so far at a range of 5110 meters which is much further than the longest confirmed kill by an M1 abrams. The M1 is a good tank but many of the key features are copied from the Challenger such as the dorchester composite armour. Secondly the fuel turbine engine used in the Abrams does not create nearly as much torque or power to weight ratio than that of the direct drive Perkins CV-12 on the challenger 2 which is an updated version of the rolls royce cv-12. The main problem with the challenger is its numbers as there are less than 400 in existance. Perhaps this is because the British Government do not see the need to produce so many tanks, or perhaps the challenger is so good that it doesnt need to be produced in such a large quantity. Finally I shall make the point that there were no challengers lost in both desert storm conflicts whereas there were 7 abrams severly damaged so much so that they had to undergo an extensive repair to the engine block and chassis. I hope this makes you reconsider before you dismiss the Challenger."

[hoggydog]

Hmmm, that looks a bit too CR2 fanboyish to me.

I don't think anyone could spin a lack of numbers as a positive. Although the long range kill is pretty well documented.

Not sure about the L28A2 round. At the end of the day anyone can say round X is better than or just as good as round Y but without hard facts its just words on the wind.

Where did you find that lavictoireestlavie?

What is FACT is that a working BV and a full load of Tea increases the operational capability of any British Army vehicle by 637%

[dejawolf]

Also what are your thoughts on this "I think you will find that the L30A1 120MM rifled cannon has claimed the longest confirmed tank kill in the world so far at a range of 5110 meters which is much further than the longest confirmed kill by an M1 abrams. The M1 is a good tank but many of the key features are copied from the Challenger such as the dorchester composite armour. Secondly the fuel turbine engine used in the Abrams does not create nearly as much torque or power to weight ratio than that of the direct drive Perkins CV-12 on the challenger 2 which is an updated version of the rolls royce cv-12. The main problem with the challenger is its numbers as there are less than 400 in existance. Perhaps this is because the British Government do not see the need to produce so many tanks, or perhaps the challenger is so good that it doesnt need to be produced in such a large quantity. Finally I shall make the point that there were no challengers lost in both desert storm conflicts whereas there were 7 abrams severly damaged so much so that they had to undergo an extensive repair to the engine block and chassis. I hope this makes you reconsider before you dismiss the Challenger."

pure propaganda. the turbine engine of the abrams delivers 5300 Nm of torque. the CV-12 delivers 4126 Nm.

[lavictoireestlavie]

Thanks hoggydog and Dejawolf. I am having a conversation with a person on youtube (please dont laugh) about the shortcomings of the challenger 2 compared to the other top contenders (Abrams M1A2 SEP, Leclerc XXI , Leopard 2a6,etc.) . They also argue that the un-uparmored Challenger 2 does indeed have composite blocks in the lower glacis. There is a lot of non scientific propaganda floating around on that site concerning these vehicles.

[lavictoireestlavie]

dejawolf i found this

http://aerospace.honeywell.com/products/engines/propulsion-engines/agt1500

and http://www.thefreelibrary.com/Building+Challenger+2.-a09038700

These sources give the Perkins CV-12 a torque of 4126 Nm at 1700 rpm and the Honeywell AGT1500 a torque of 3730 Nm at 3000 rpm

[Tjay]

Both Rh120 (Leopard 2) and M256 (M1A1/A2) are 44 calliber long.

Could someone put me right on the use of the word 'caliber' as applied to tank guns please? Wikipedia says:

In guns, particularly firearms, caliber or calibre is the approximate internal diameter of the barrel, or the diameter of the projectile it fires.

and

In some contexts, e.g. guns aboard a warship, "caliber" is used to describe the barrel length as multiples of the bore diameter. A "5-inch 50 calibre" gun has a bore diameter of 5 inches (12.7 cm) and a barrel length of 50 times 5 inches = 250 inches (6.35 m).

Thanks in advance.

[DarkLabor]

Could someone put me right on the use of the word 'caliber' as applied to tank guns please?

As Damian said the guns are 44 caliber long wich correspond to the second definition of your wikipedia quoting.

[dejawolf]

dejawolf i found this

http://aerospace.honeywell.com/products/engines/propulsion-engines/agt1500

and http://www.thefreelibrary.com/Building+Challenger+2.-a09038700

These sources give the Perkins CV-12 a torque of 4126 Nm at 1700 rpm and the Honeywell AGT1500 a torque of 3730 Nm at 3000 rpm

yes, those figures are correct, but maximum torque of a turbine engine is at lower RPM.

the figure i posted is at 1000RPM.

this graph shows typical power curve of a turbine vs a typical diesel engine:

[lavictoireestlavie]

yes, those figures are correct, but maximum torque of a turbine engine is at lower RPM.

the figure i posted is at 1000RPM.

this graph shows typical power curve of a turbine vs a typical diesel engine:

Thanks for clearing this up for me Dejawolf

[Tjay]

yes, those figures are correct, but maximum torque of a turbine engine is at lower RPM.

the figure i posted is at 1000RPM.

this graph shows typical power curve of a turbine vs a typical diesel engine:

Musn't confuse torque with power tho. Power being torque x rpm. Also, a turboshaft engine (gas generator plus high ratio reduction gearbox) will produce high torque at quite a low output shaft rpm while the gas generator (pure jet) part will be revving a lot higher. Torque figures for diesel engines are always quoted at the crankshaft.

[Tjay]

As Damian said the guns are 44 caliber long wich correspond to the second definition of your wikipedia quoting.

Understood - thank you. So is there a standard way of describing tank main guns that states both the bore and the length of the barrel?

[DarkLabor]

Understood - thank you. So is there a standard way of describing tank main guns that states both the bore and the length of the barrel?

Well, it depends on the way constuctor name it's products.

On a practical level, people talk about the length in caliber, because the caliber of the gun is most likely known.

By example, in France, we tend to name the gun according to it's caliber like CN120-26 (26 being the number of the design), CN105 F1 (the designation is from the army (my bad!) and F1 stands for Fabrication n=°1), etc. With this nomenclature, you only need to precise the length in caliber to get all the values.

[dejawolf]

Understood - thank you. So is there a standard way of describing tank main guns that states both the bore and the length of the barrel?

usually it'll be in a format like 120mm L44, or 120mm L55.

120mm is caliber of gun, L44 is length of barrel in calibers.

[GSprocket]

Everything I've seen about the L28 projectile indicates that it is a cut down version of DM53 projectile fitted to a rifled-gun compatible sabot and fin protector, fired at similar velocities to DM53 from an L44 barrel.

Stowage requirements being the same for both (I can't imagine that L28 can be significantly longer than L27 as it has to fit the same racks, and L27 was the 'goal' development of the CHARM round.

With similar velocity, similar dimensions the difference in performance between L27 and L28 is going to be marginal ~ though it may favour L28 at shorter ranges.

Whether L27 is set at the correct level is arguable (though it may be correct-er than some of the other rounds... I'd assess many as being significantly optimistic based on known dimensions and the curve fits from Lanz-Odermatt for DU and WHA rods). In particular highly sloped impacts are more efficient than normal ones. 'Test' arrays are usually either large and highly sloped thin plates with perforation LOS given, or stacks of small, poorly constrained blocks hit normally when the penetration into the stack is given. Often the penetration into the stack approximates the perforation limit at 60-70 degrees (this stated and re-stated by Wili Odermatt on several occasions), and is some 15-25% more than the perforation limit in a normal impact (i.e. the maximum armour thickness than can be perforated at any angle).

[Tjay]

usually it'll be in a format like 120mm L44, or 120mm L55.

120mm is caliber of gun, L44 is length of barrel in calibers.

Many thanks to you and Dark Labour for this information. At last I know the significance of the 'L' number.

[GSprocket]

Careful, because in our infinite wisdom the UK chooses to use L to designate it's individual model weapons/ammunition at just about everything else.

e.g.

L7 105mm gun is L/52 or thereabouts

L11 120mm gun and L30 120mm gun both L/55

L15 - a 120mm APDS round

L23, L26, L27, L28 - 120mm APFSDS rounds

L23 76mm gun is unclear ~ I've seen both L/23 and L/28 quoted for it.

L85/L86 are rifle and SAW in 5.56mm

etc, etc

[Volcano]

Careful, because in our infinite wisdom the UK chooses to use L to designate it's individual model weapons/ammunition at just about everything else.

e.g.

L7 105mm gun is L/52 or thereabouts

L11 120mm gun and L30 120mm gun both L/55

L15 - a 120mm APDS round

L23, L26, L27, L28 - 120mm APFSDS rounds

L23 76mm gun is unclear ~ I've seen both L/23 and L/28 quoted for it.

L85/L86 are rifle and SAW in 5.56mm

etc, etc

Sort of like the US' use of the "M"?

M1 tank

M1 rifle

M1 toilet paper roll

M1... etc.

(or maybe this is worse)

[Tjay]

Careful, because in our infinite wisdom the UK chooses to use L to designate it's individual model weapons/ammunition at just about everything else.

e.g.

L7 105mm gun is L/52 or thereabouts

L11 120mm gun and L30 120mm gun both L/55

L15 - a 120mm APDS round

L23, L26, L27, L28 - 120mm APFSDS rounds

L23 76mm gun is unclear ~ I've seen both L/23 and L/28 quoted for it.

L85/L86 are rifle and SAW in 5.56mm

etc, etc

Aaaaaaaaaaargh! But thank you for the information. So I guess the only thing to do is to make a note of the official designation of the gun and look up the exact spec somewhere?

[Assassin 7]

dejawolf i found this

http://aerospace.honeywell.com/products/engines/propulsion-engines/agt1500

and http://www.thefreelibrary.com/Building+Challenger+2.-a09038700

These sources give the Perkins CV-12 a torque of 4126 Nm at 1700 rpm and the Honeywell AGT1500 a torque of 3730 Nm at 3000 rpm

AGT1500 Here:

Gross torque at 3000 rpm

NBC on-2561 lb-ft

NBC off-2626 lb-ft

Maximum torque at 1500 rpm

NBC on-3842 lb-ft

NBC off-3885 lb-ft=5267.35273575 Nm

Response Transient, idle to 90% rated power

4 sec

Power decay, 100 to 20% power

5 sec

[GSprocket]

The actual length isn't *too* critical though. The 25% increase in tube length L44>L55 gives less than 5% increase in muzzle velocity for properly tuned rounds, and less than 10% more kinetic energy. This is why the US finds the L44 still adequate, and why most upgrade programs for the Leopard were looking at L44 model gun tubes still (a few had L55 options, but there are compromises in accuracy, stabilisation and close-terrain flexibility with the longer gun).

I think the French 120mm is an L52, as are the Soviet 125mm guns FWIW.