Weight distribution on different tanks.
Weight distribution on different tanks.
Guys, I would like to see the weight distribution difference between some tanks of the Ostfront:
Soviet BT, T-34 and KV tanks,
German Pz II, III and IV tanks.
(in different versions, if possible)
Would any of you have this information to share here with us? It`s a math I guess.
Best Regards.
Soviet BT, T-34 and KV tanks,
German Pz II, III and IV tanks.
(in different versions, if possible)
Would any of you have this information to share here with us? It`s a math I guess.
Best Regards.
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Re: Weight distribution on different tanks.
What kind of weight distribution are You referring to?
Re: Weight distribution on different tanks.
I`m referring to the weight on tracks width. For instance, they say that the T-34 tank would have much better mobility on the snow than the Pz III because it had wider tracks. I would like to make a comparison between those tanks. There`s actually a calculation that could be made to reach the real number.
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Re: Weight distribution on different tanks.
That´s netto or nominal ground pressure.
However, ground pressure is a poor proxy for cross country mobility because it ignores variances in pressure along the length of the track. Such a procedure is ok vs hard surfaces where the transfer mechanics are rigid and sinkage is a non factor but on softer ground, where the vehicle sinks in local stresses caused by the pressure rise of the roadwheels make for significant deviations from the hard surface interaction mechanics. The tracks themselves are flexible -along with the soil, which is partially depressable and therefore one is confronted with a mechanic which does not represent a rigid transfer medium anymore.
Rowland worked out the principles. Some of his research papers can be found in the internet. He and later Ogorkiewicz note that a high number of small road wheels will be benefitial in soft soil interaction (f.e. Churchill, Mathilda, IS) but create more rolling resistence than large diameter road wheels (some designs got around this with a large number of large roadwheels using interlocked or overlapping layouts with excellent results).
For the MMP to calculate You need
W= weight of vehicle in KN
n= number of roadwheels per side
b= track width in m
p= pitch of track links, in m
d= diameter of roadhweels, in m
MMP= .63W/((n x b x c) (p x d)^.5)
where c is the ratio of actual plan area of a track link to the product of p and b
he gives the following data:
PzIIIJ: 220KN/m^2
PANTHER: 150KN/m^2
SHERMAN VVSS: 282KN/m^2
SHERMAN HVSS: 205KN/m^2
Churchill Mk IV: 177-217 KN/m^2 (depending on sinkage)
BT-5: 175KN/m^2
BT-7: 240 KN/m^2
T-34/76: 174KN/m^2
CROMWELL MK IV: 352KN/m^2
CROMWELL MK VII: 300 KN/m^2
TIGER Ausf. B: 184KN/m^2
ELEFANT: 370KN/m^2
E100: 250KN/m^2
MAUS: 470KN/m^2 (hardly readable in my copy)
If one uses MMP as a proxy of soft soil interaction, the thesis of improved cross country mobility of BT-5 and T34/76 vs Pz-III can be readily confirmed.
The MMP of some AFV by Ogorkiewicz are only slightly different from those of Rowland above:
COVENANTER: 370KN/m^2
MATHILDA II: 252KN/m^2
CROMWELL IV: 368KN/m^2
CENTURION V: 275KN/m^2
TIGER Ausf. B: 190KN/m^2
PANTHER: 157KN/m^2
T54: 242KN/m^2
LEOPARD 1: 223KN/m^2
Ogorkiewicz, R.M., Technology of Tanks Part I (Coulsdon 1991), pp.346-348.
hope it helps,
cm
However, ground pressure is a poor proxy for cross country mobility because it ignores variances in pressure along the length of the track. Such a procedure is ok vs hard surfaces where the transfer mechanics are rigid and sinkage is a non factor but on softer ground, where the vehicle sinks in local stresses caused by the pressure rise of the roadwheels make for significant deviations from the hard surface interaction mechanics. The tracks themselves are flexible -along with the soil, which is partially depressable and therefore one is confronted with a mechanic which does not represent a rigid transfer medium anymore.
Rowland worked out the principles. Some of his research papers can be found in the internet. He and later Ogorkiewicz note that a high number of small road wheels will be benefitial in soft soil interaction (f.e. Churchill, Mathilda, IS) but create more rolling resistence than large diameter road wheels (some designs got around this with a large number of large roadwheels using interlocked or overlapping layouts with excellent results).
For the MMP to calculate You need
W= weight of vehicle in KN
n= number of roadwheels per side
b= track width in m
p= pitch of track links, in m
d= diameter of roadhweels, in m
MMP= .63W/((n x b x c) (p x d)^.5)
where c is the ratio of actual plan area of a track link to the product of p and b
he gives the following data:
PzIIIJ: 220KN/m^2
PANTHER: 150KN/m^2
SHERMAN VVSS: 282KN/m^2
SHERMAN HVSS: 205KN/m^2
Churchill Mk IV: 177-217 KN/m^2 (depending on sinkage)
BT-5: 175KN/m^2
BT-7: 240 KN/m^2
T-34/76: 174KN/m^2
CROMWELL MK IV: 352KN/m^2
CROMWELL MK VII: 300 KN/m^2
TIGER Ausf. B: 184KN/m^2
ELEFANT: 370KN/m^2
E100: 250KN/m^2
MAUS: 470KN/m^2 (hardly readable in my copy)
If one uses MMP as a proxy of soft soil interaction, the thesis of improved cross country mobility of BT-5 and T34/76 vs Pz-III can be readily confirmed.
The MMP of some AFV by Ogorkiewicz are only slightly different from those of Rowland above:
COVENANTER: 370KN/m^2
MATHILDA II: 252KN/m^2
CROMWELL IV: 368KN/m^2
CENTURION V: 275KN/m^2
TIGER Ausf. B: 190KN/m^2
PANTHER: 157KN/m^2
T54: 242KN/m^2
LEOPARD 1: 223KN/m^2
Ogorkiewicz, R.M., Technology of Tanks Part I (Coulsdon 1991), pp.346-348.
hope it helps,
cm
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Re: Weight distribution on different tanks.
This is amazing! Thank you very much for this information, Critical Mass!
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Re: Weight distribution on different tanks.
I want to use the equation myself but when trying to find the Sherman's Kn/m^2 I got a vastly different number on orders of magnitude larger. I do not understand "c" as shown in the MMP equation below. I believe that is the problem.
If the "actual plan area" is the area that is useful on the track I have no way of finding this out and making a "ratio" with the prpduct of length and width (p x b). I tried bruting through without a ratio. That is all I could find without c existing elsewhere.critical mass wrote: ↑15 Nov 2018, 19:33For the MMP to calculate You need
W= weight of vehicle in KN
n= number of roadwheels per side
b= track width in m
p= pitch of track links, in m
d= diameter of roadhweels, in m
MMP= .63W/((n x b x c) (p x d)^.5)
where c is the ratio of actual plan area of a track link to the product of p and b
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Re: Weight distribution on different tanks.
Could someone explain "c?" I don't understand what the actual plan area of the track is and how to get it or the ratio.critical mass wrote: ↑15 Nov 2018, 19:33For the MMP to calculate You need
W= weight of vehicle in KN
n= number of roadwheels per side
b= track width in m
p= pitch of track links, in m
d= diameter of roadwheels, in m
MMP= .63W/((n x b x c) (p x d)^.5)
where c is the ratio of actual plan area of a track link to the product of p and b
Re: Weight distribution on different tanks.
It's a constant specific to a given design of tracks. For most cases, it should be slightly less than 1. I would use 0,9.admiralTANK wrote: ↑15 Jul 2021, 07:46Could someone explain "c?" I don't understand what the actual plan area of the track is and how to get it or the ratio.
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Re: Weight distribution on different tanks.
image "c" as a coverage facor, showing how much of the pitch x tracklength footprint area of a tracklink is actually in contact with soil and presents an interface.
Re: Weight distribution on different tanks.
https://www.slideshare.net/wolfhag/trac ... d-pressureCould someone explain "c?" :
Here are Rowlands original words.
Note that these are soil insensitive calculations and do not have track-terramechanics interaction, but still prove useful for a general overview. You would need something like a NTVPM predictive model (Wong, Bekker), in which the results can vary of course. It also depends on whether they are dry or combat weights.
The index of efficiency as Pmax/Pmean is also of interest (notice the differential between tyres and tracks), e.g.:
Mark V: 1.46/1.63 (@0.25 sinkage)
Churchill (Mk.IV): 2.36/2.54 (@0.14)
Cromwell IV/VII 3.4/3.15
Panzer III: 2.4-2.7
Panzer IV G: 2.1
Panther (Ausf.D): 1.72
Tiger I (E): 1.98-2.01
Tiger II: 1.7
Elefant: 3.5
BT-5/7: 2.35/3.0
T-34/76: 2.5-3.0 (1943)
Sherman (HVSS/VVSS): 2.82
Sherman VC: 3.07