Fully tracked APCs for ww2: not worth it; or, why they didn't think of those?

IMHO they well presented the different armament ideas of Germany and USA. Germans tried to achieve technical superiority but theirs tended to be more complicated and US paid more attention to productively. And as in trucks, M3 had more powerful engine in fact it had 47% more power. US armoured divs had armoured h/ts to all their 3 armoured Inf Battalions, in German PzDivs usually only one of 4 PzGrenBattalions rode in Sd.Kfz 251s others were truck-borne.

Juha

The companies, White and Dodge, that manufactured the M3, also used engines that were already in production....namely engines that were used in trucks and busses, which helped keep the cost down.

Added: meant to say that the existing engines kept cost down AND production numbers up...

"... Ride and armor protection were inferior to German made counterparts."


How many M3's can I have for one superior PanzerTraker Sd.Kfz.251, Mr. Bender ...

MM

Mr. Bender still seems to be using the "official" exchange rate if he thinks that a Sd.Kfz.251 is cheaper than an M3.

tomo pauk said:

Maybe you're misuderstood my mentioning of all the tanks in the above post - I'm not saying that those were to be converted into APCs (not my 1st call anyway), but to point into the fact that some armies were awash in tanks, yet had (almost) none of well protected APCs that might carry infantry to within hundreds of meters close to the front line. Under 'well protected', I assume that a gun equal to 50mm or better was needed to tackle those.
Regarding to the number of vehicles to carry a squad, the U. Carrier carried 5 crew, driver included. Falls well within the 'lousy APCs' group?

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Some of those tanks were mistakes, unfortunately for the British (and some other countries) they were not "awash in tanks" at the time they were being made. Some of the them were being cranked out in times of desperation when good tanks were in short supply.
If you are looking for an APC that is resistant to 50mm gun fire you need a 30 ton tank or better for starters. Which takes out just about all of the tanks mentioned. German Pak 38 could penetrate 61mm of vertical plate at 1000yds?

The Bren carrier was not really supposed to be an APC, it was a scout vehicle or more properly a vehicle to carry an infantry scout section. It also provided mobility for company or battalion support weapons. It started as the Vickers carrier as in Vickers machine gun. It wound up carrying 3 in mortars although in some early versions the mortar could not be fired from the vehicle. It sure did beat men on foot lugging the barrel, base plate and bipod around, not to mention a quantity of ammo. Same with the Vickers gun. It provided mobility for a 100lb+ support weapon, a quantity of ammunition and it's crew that would not be able to keep on the battle field when carried on foot.

Wiki gives as short over view: Universal Carrier - Wikipedia, the free encyclopedia

tomo pauk said:

Agreed 100%. That's why I'm talking about a 'classic' APC as a better solution.

There were no 'classic' APCs in WW II although the concept isn't really that difficult, move engine and drive line to the front, put big door in back. However the difference between bullet and shell fragment proof and even 37-50mm proof is 10-15 tons. you jump from light tank components (even if you don't use the hull) to medium tank components.

as an example of size try the US M75 APC, work began from a 1945 requirement. see wiki:

M75 armored personnel carrier - Wikipedia, the free encyclopedia

and

http://www.tanksintown.be/Ressources Photos/SHAR_M75.JPG

Please be aware that the armor thickness on wiki may be suspect.

tomo pauk said:

SP tracked artillery was present in major armies. Plus, many of them towed their guns by half tracks or fully tracked vehicles; such arty did not needed to close within hundred of meters to the enemy. The APC needed to closely follow the tanks or assault artillery were not that present, though.

It was present but not in the numbers desired. Towed artillery has trouble keeping up with pace of an armored advance. Large towed guns/howitzers can take over a 1/2 hour from unlimber to first shot and getting a battery (and como system) set up can take quite a bit longer. It is this delay between stopping the towed artillery and getting of the first shots that allow the leading elements of the advance to get beyond effective artillery support range. Not just the cross country mobility.

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Sd.Kfz.10 / Sd.Kfz.250. About 21,000 produced @ 15,000 RM each. Light towing tractor / light APC.
.....Sd.Kfz.250 is APC version of the Sd.Kfz.10 towing tractor.
Sd.Kfz.11 / Sd.Kfz.251. About 25,000 produced @ 22,000 RM each. Medium towing tractor / medium APC.
.....Sd.Kfz.251 is APC version of the Sd.Kfz.11 towing tractor.

What's wrong with German production quantities or production costs? They compare favorably to the inferior U.S. M3 half track.

Just why is the M3 inferior? in which roles?

Costs based on the "exchange rate" will tossed in the garbage unless you can explain how the Germans could produce the P-38 pistol at the same or lower cost as the US single shot, stamped sheet metal, smooth bore Liberator pistol.

Sometimes I would wish more objectivety.

The US Army had a comparative test at 1943 between M3 and Sd.Kfz.251!
At this test the US Army stated that the Sd.Kfz.251 armour layout and in general the armour was much better then the M3, the cross country mobility was much better and also the cooling system was better under fire and more reliable.

The M3 was larger with more room, had the powered front suspension and a better mobility on streets.

The M3 had very heavy losses at North Africa at the Battles of Kasserine beginning 1943), as the Wehrmacht was a little more competitive then 1944 or 1945

How many M3's can I have for one superior PanzerTraker Sd.Kfz.251, Mr. Bender ...

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IMHO they well presented the different armament ideas of Germany and USA. Germans tried to achieve technical superiority but theirs tended to be more complicated and US paid more attention to productively. And as in trucks, M3 had more powerful engine in fact it had 47% more power. US armoured divs had armoured h/ts to all their 3 armoured Inf Battalions, in German PzDivs usually only one of 4 PzGrenBattalions rode in Sd.Kfz 251s others were truck-borne.

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To me the coments are not objective. The M3 was 2 tons heavier then the Sd.Kfz.251, so the 47% more power is rubbish at the power to weight ratio 13,5ts to 16ts. Also I can't see that the Sd.Kfz.251 is overengineered or too expensive, when it had 2 tons less weight, because of a smaler room but a much better sloped armour layout.
Why is here anyone thinking that the Sd.Kfz.251 is more expensive then the M3. Do you have any numbers?
Not all german equipment is overengineered and expensive!

Also the Sd.Kfz.251 was back in Production at 1958 as OT-810 at the czech republic to replace the BTR-152 and was in service till the 1980's. From all I have read from military experts the Sd.Kfz 251 was credit as a very successful and reliable construction.

I think I was being very objective. I did not state that the M3 was superior to the Sd.Kfz.251. I asked how it was inferior.

Both types had areas that they better in than the other. Especially for certain specialized roles. Perhaps the Sd.Kfz.251 was better overall but it takes quite a list to make the assessment and not picking just a few facts.

Which has the better trench crossing ability?
Which has the better vertical obstacle ability?
Which can climb a steeper gradient or restart on the steeper gradient?
Which has the better towing ability and are they being measured the same way?

and so on.

As far as cost goes the Sd.Kfz.251 used a more complicated armor layout. More pieces that meet in more complicated joints. It was better for protection. The Germans simplified later models to cut costs.

The German track system was more expensive.

The American front axle was more expensive.

The German steering system was more expensive.

To get back OT.

a box carrier like a M113 big enough to hold 12 men was going to run 15-20 tons. This pretty much rules out using most of the smaller light tank engines. Like the British MK VI light tank or the German MK II engines and so on. Likewise the transmission/steering gear. Suspension may call for more than just an extra road wheel.

The idea of an APC is a good one. It is just that few, if any, countries had the industrial capacity to make them in large enough numbers to equip more than a few divisions.

There is also a difference between an APC and IFV (infantry fighting vehicle). Infantry was NOT supposed to fight from inside the APC.

Let's not forget that the U.S. Marines used an armored transport LVT-1, called an AmTrac (amphibious tracked vehicle) that carried up to 24 personnel and a crew of 3.

There were several upgrades to the AmTrac, ending in the LVT-4, but it remained a stable workhorse throughout the pacific theater.

Half tracks

Some comparisons

(251/M3)
Weight (Tons) 8.7 9.3
Hp 100 143-147
Power to weight (hp/ton) 11.5 15.8
Speed (mph) 32 45
Armor, max (in.) .47 .512
Crew 2+10 3+10
Ground Clearance (in.) 12.6 11
Range (miles) 217 200
Max angle of climb degrees 24 60 (30)
Fording ability (in.) 19 32
Turning radius (ft) 36 60

"Objectively" speaking it appears that the M3 is .6 of a ton heavier with 47% more hp giving it about a 37% better power to weight ratio. It also has 40% better speed capability, important if you want to keep up with Patton. Due to slanted armor, the 251 has better protection, but not a lot. Personnel carriage is basically even. The 251 has slightly better ground clearance which is important and slightly better range. In climbing ability, the M3 is better (there seems to be some conflict in data here as many site state it is 60 degrees and one 30. I believe in 30). Fording ability, important, is an advantage for the M3. Turning radius, also important is much better in the 251, most likely do to the use of track braking.

"Subjectively" speaking the two are very good halftracks with different characteristics, each show an advantage in important areas, the 251 in armor, ground clearance, turning radius, and general rough terrain ability. The M3 has advantages in power to weight, speed, climb angle and fording ability. In addition, both apparently soldiered on after the war with the M3 participating in the Israeli-Arab wars.

To state that one is significantly better and the other is … not stating "objectively"!

davebender said:

Track suspension carries most of vehicle weight and it's the same state of the art schachtellaufwerk suspension employed on Panther and Tiger tanks.

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Were there any post WWII tanks that adopted this "state of the art" suspension system? Maintenance on those inboard rollers must have been fun.

Protective armor is nicely angled too. Vehicle may be steered using tracks. That's important for a combat vehicle as one or more front tires are likely to be shot out when bullets start flying.

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All good comments

Amazingly enough this superior WWII era APC was also slightly less expensive then the U.S. made M3 Half track.

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To use your line

The difference is obvious if you look at vehicle pictures.

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Note the complex front end, the multi-angled armor, and the highly complex suspension system of the 251. It is indeed obvious that the manufacturing manhours would be significantly lower for the M3. After all, "it is only a commercial truck with armor attached, fairly cheap system". I would bet that the American automobile industry was the most efficient in the world.

Ride and armor protection were inferior to German made counterparts.

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I suspect you have no idea how the M3 rides.

DonL said:

Sometimes I would wish more objectivety.

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That works both ways.

The US Army had a comparative test at 1943 between M3 and Sd.Kfz.251!
At this test the US Army stated that the Sd.Kfz.251 armour layout and in general the armour was much better then the M3, the cross country mobility was much better and also the cooling system was better under fire and more reliable.

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I am sure armor was better. However, the M3 was faster, could ford deeper rivers, could climb more steep inclines, and high tail it on a decent road, so, I guess it depends on the terrain that is being crossed on which one is better.

The M3 had very heavy losses at North Africa at the Battles of Kasserine beginning 1943), as the Wehrmacht was a little more competitive then 1944 or 1945

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Inappropriate comparison. At Kasserine the M3 was missed used as an anti-tank vehicle with an inadequate anti-tank gun and when they confronted the Africa Corps tanks they were predictably massacred as was the American tanks and the inexperienced, poorly trained and incompetently led American soldiers. I am sure that under the same circumstances the 251 would have fared no better.

To me the coments are not objective. The M3 was 2 tons heavier then the Sd.Kfz.251, so the 47% more power is rubbish at the power to weight ratio 13,5ts to 16ts.

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You can see the power to weight ratio above. And, Speed is Speed. I don't see any lack of objectivity. Data may be different but challenge the data not the objectivity of the poster.

Also I can't see that the Sd.Kfz.251 is overengineered or too expensive, when it had 2 tons less weight

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I don't think the M3 is two tons heavier than the 251. Data is variable but my book "The Encyclopedia of Tanks and Armored Fighting Vehicles" shows the data I posted as does Wikipedia.

, because of a smaler room but a much better sloped armour layout.
Why is here anyone thinking that the Sd.Kfz.251 is more expensive then the M3. Do you have any numbers?

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I don't but horse sense tells another story.

Not all german equipment is overengineered and expensive!

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VWs were indeed cheap, simple and reliable. Nor is all German equipment superior to it allied counterpart.

Also the Sd.Kfz.251 was back in Production at 1958 as OT-810 at the czech republic to replace the BTR-152 and was in service till the 1980's. From all I have read from military experts the Sd.Kfz 251 was credit as a very successful and reliable construction.

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No doubt that the 251 was all you said. However, the M3 also continued successfully in service apparently as late a 2006. It is not a design to dismiss as inferior.

Please check your sources, you are mixing short tons with metric tonnes, the 251 weighted ~7.5 tonnes while the M3 weighted 9.3 tonnes

(251/M3)
Weight (Tons) 8.7 9.3
Hp 100 143-147
Power to weight (hp/ton) 11.5 15.8
Speed (mph) 32 45
Armor, max (in.) .47 .512
Crew 2+10 3+10
Ground Clearance (in.) 12.6 11
Range (miles) 217 200
Max angle of climb degrees 24 60 (30)
Fording ability (in.) 19 32
Turning radius (ft) 36 60

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This numbers are incorrect for the Sd.Kfz.251!

Correct numbers after Walter J. Spielberger:

Weight: 7,4 t!
Power: 100PS
Power to weight (hp/t): 13,5PS/t
Speed: 52,5 km/h (32,6 miles)
Ground Clearance mm (in.): 320mm (12,6)
Fuel capacity: 160l
Range km (miles): 320km (200) / to my books range of the M3 was 282 km (175miles) with 230liter (60USg)
Fording ability (in.): 500mm (19,7)
Turning radius (ft) : 13,5m (44)

For US use the climb grade is actually a percent and not in degrees. the US half track will climb a 60% slope. that is a slope that rises 6ft for every 10 ft of horizontal difference.

Please note that a 100% slope is 45 degrees. Also note that for a US vehicle to be rated at 60% the vehicle had to parked on a 60% slope, the engine turned off and then restartted, and then the vehicle had to start moving again on the 60% slope. There is/was a man made hill at Aberdeen proving grounds that was 60% on one side where this test took place. a safety cable was often routed over the hill to prevent accidents or rolling back too far.

The US used two different engines in the halftracks. the normal engine was a 6.3liter six compared to the 4.2 liter six in the German halftrack. Torque is much more related to engine displacement than horsepower is. The alternate engine, used almost entirely for lend-lease was a 7.4 liter six of about the same peak power but lower revving.

when comparing weights please check to see if they are "factory empty", combat ready or loaded. or something in between.

Being objective I would say the range is too close to call, unless this is a bar bet. 1953 US catalog of vehicles claims a range of 210 miles for the M3 on 60 gallons, speed and load not stated. Since the German half track falls in the middle of the highs and lows of the American claims and as we ALL KNOW " YOUR gas mileage may VARY i would call this this one a draw. At best the German track gets 6% more range.

when comparing weights please check to see if they are "factory empty", combat ready or loaded. or something in between.

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The weight of the Sd.Kfz.251 with armour, armament and fuel (combat ready) was 7,4t!
The payload was 1,1t.

Edit:

Maximum angle of driving 24 degrees
Later Versions had 7,5 t and a payload of 1,5t the maximal weight was 9t, with all equipment and soldiers!

Here are the two APCs based upon the T-26, made in 1933-35. Transporting 13 and 14 soldiers, respectively. Swedish PBV 301, based upon the license produced copy of the Pz-38(t), was carrying 2+8, but it looked far more a refined design.

Denniss said:

Please check your sources, you are mixing short tons with metric tonnes, the 251 weighted ~7.5 tonnes while the M3 weighted 9.3 tonnes

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My reference does show the 251 and M3 weight in kg, 8500 for the 251 and 9472 for the M3, which still comes up to 37% more power to weight ratio. Of course I don't really know if those are English kgs or American kgs.

The reference is English and the numbers are in long tons.

DonL said:

This numbers are incorrect for the Sd.Kfz.251!

Correct numbers after Walter J. Spielberger:

Weight: 7,4 t!
Power: 100PS
Power to weight (hp/t): 13,5PS/t
Speed: 52,5 km/h (32,6 miles)
Ground Clearance mm (in.): 320mm (12,6)
Fuel capacity: 160l
Range km (miles): 320km (200) / to my books range of the M3 was 282 km (175miles) with 230liter (60USg)
Fording ability (in.): 500mm (19,7)
Turning radius (ft) : 13,5m (44)

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There is a lot of contradictory data available from reliable sources on both vehicles. As SR stated, range varies. However, if I take your data directly, what would you change in the statement I made except adding range (questionable) to the 251 advantages.

"Subjectively" speaking the two are very good halftracks with different characteristics, each show an advantage in important areas, the 251 in armor, ground clearance, turning radius, and general rough terrain ability. The M3 has advantages in power to weight, speed, climb angle and fording ability."

I've got 3 books before me right now, and i've got more, but the 3 vary on the KFZ.251 weight a bit.
Bk# 1 9.4 tons
Bk#2 8.4 tons
Bk#3 7.93 tons, or 8.74 tonnes they got tons and tonnes reversed. As some of us may.

There's the ton or short ton 2000 lbs, mostly a USA form of measurement
There's the long ton, 2240 lbs United Kingdom, Commonwealth, and the US Navy, just to confuse us all.
There's the metric ton, or tonne, or t, 2204 lbs, used by the rest of the world.

Anybody got a SD.KFZ.251? I've got access to some big scales.

Weights for the different models vary but the 1953 TM 9-2800-1 technical manual for Military vehicles gives the net weight of of the M3 halftrack (not the M3A1) as 15,500lbs, payload as 4500lbs and gross weight as 20,000lbs. Net weight is defined on page 1 of the manual as " Weight of the fully equipped vehicle in operating condition with fuel, lubricants, and water, but without crew or payload, unless otherwise specified."

The M2A1 half track is listed at 14,600lbs net, 5000lbs payload and 19,600lbs gross.

Max recommended towed load, cross country, is 4,500lbs but the British used them to tow 17pdr AT guns in the post war Army of the Rhine. maybe they had the 7.4 liter engine version?