Movement of guns and tanks

[mav1]

Why should the soviet 100mm anti tank gun be immobile in the game, when the British 17pdr is not?

How long would it take to set up the 100mm gun?

Another question is does it really take a tank more than 1m to rotate 360 degrees in a stationary position (i have no idea) ?

[JoMac]

Hello Mav,

Not really sure about the AT gun question but its probably due to the 17pdr ( 77mm gun ) being a medium class and the 100mm gun being bigger.

Many of the vehicles in my opinion rotate and move thru cover much to slow in CMBB and CMAK then it does in CMBO. How i so much missed the CMBO vehicle movement.

[ June 15, 2006, 07:04 AM: Message edited by: JoMc67 ]

[zmoney]

The German 88mm is immobile as well.

[76mm]

does it really take a tank more than 1m to rotate 360 degrees in a stationary position

I was hoping that one of the experts would answer, but since not I'll toss in my two cents: I would expect that for WWII tanks it would take a minute or more to rotate 360 degrees, and most of them probably couldn't rotate 360 degrees in a stationary position at all. This is the "pivot steer" in which (I think) one track goes forward and one backward. Modern tanks can do this, but I think most models of that era could not--I think the best that they could do was stop one track while continuing with the other, and you might not want to do even that because I can't imagine that such a maneuver would be good for the track on the stationary side. Can any of the grogs confirm/deny?

[MikeyD]

German halftracks in particular can't pivot steer, relying entirely on steering the front wheels. That's why they're so positively awul at turning in place in the game.

From conversations with modern tankers even the tanks that can pivot in place (Panther and Tigers can I believe) often hesitate to do it on anything other than a flat parade ground surface. Too much of a chance of accidentally shedding a track in the process. Still CMBB pivot is a bit slow, that's why it was boosted in CMAK - otherwise that Brit TD with the rearward facing gun on the Valentine chassis would've taken 2 1/2 minutes to pivot to rotate to face the enemy!

[ParaBellum]

I once saw an M1 Abrams tank almost get immobilized while turning on cobblestone pavement. It was during a vehicles show at Koblenz armour museum, and Lindan and Warphead were standing next to me, chanting "Bog down! Bog down!".

That was shortly before Lindan close-assaulted a Flammpanzer III with a beer bottle.

Good times.

[JoMac]

Yes i also think that rotating in CM can also represent vehicles moving back and forth to face the desired location.

If CM were to represent in real life the 360 degree back and forth motions of a vehicle then you would have to put in several way points that in turn could take several seconds to a minute just to finally start moving.

On a closely related subject its a shame that there is no " Follow the Road " order so that in just 10 or 15 seconds the vehicle can start to move to get to its destination. Instead you have to put in a way point at every bend in the road that in turn could take up to a minute for the vehicle to finally start moving.

[ June 16, 2006, 02:11 PM: Message edited by: JoMc67 ]

[MikeyD]

I believe something like that s supposed to show up in CMx2... if only CMx2 would show up!

[Fenris]

Originally posted by ParaBellum:

That was shortly before Lindan close-assaulted a Flammpanzer III with a beer bottle.

Good times.

heh, good story

[Tim Hughes]

I have a friend who works at the IWM Duxford, he regularly drives tanks (apparently rather enjoyable) and had this to say on the subject of turning tanks when I asked (for other reasons):

What I can tell you is that a Second World War tank steers because of

the speed differential between tracks. To turn right the right hand

track is slowed and the 'outer' (faster) track pulls the tank round.

(but you knew that.) This is all done via braking (some WW2 tanks have a

differential whereby as one track is braked, extra power is applied to

the other track - thus increasing the differential and allowing a

sharper turn at a given speed.)

Post war tanks (the Chieftain for example) can vary the power output to

each track via the gearbox (in some cases, the T-72 for example - the

tank has two separate steering gearboxes - one for each track). This

means steering is not dependant on braking (but it still has a part to

play - brakes are still applied when steering is initiated.) Another

upshot of this is the so called 'neutral turn'. This means that on many

modern tanks equal and opposite power can be applied to each track at

the same time and the vehicle can therefore turn 'on the spot'.

Back to WW2 tanks..

The faster you are going forwards when steering (and therefore braking)

is applied the wider the turning arc of your vehicle. I suppose that

this is because although there is still a speed differential between the

tracks at higher speeds when the turn is initiated both tracks are

travelling that much faster and the tank will have moved further by the

time the rather crude braking system comes into effect (does this make

sense?) Also a tank weighing 25 tons moving at 20mph is going to have

much more resistance / inertia than one moving at 10mph. Thus the

mechanical systems controlling turning will need more time and

application to work effectively. I think? Any how all the manuals give

wider turning arcs at higher speeds.

There comes a point (depending on the inertia of your tank and the

capability of its braking system) where you try and turn a tank and you

just go straight on! This is quite easy when tank driving, it is quite

easy to 'lose' say a Sherman when trying to turn at speeds as low as 15

miles an hour. This point varies considerably dependant on the ground

you are moving on. You have to turn at much lower speeds on wet ground.

A vehicles tank driver manul will tell drivers at what speeds and in

what gears turns are safe and what expected arcs of turn should be in

'average' conditions (but there are many variables.)

In just the same way that an experienced racing car driver can feel

when a car is on he edge of spinning or skidding a tank driver can feel

when he is about to push the vehicle past it limits. This only really

comes with experience of driving that sort of tank.

Your turning arc will depend on variables such as ground pressure,

power to weight ratio, forward inertia (your arc will be wider if you

are heading down hill) - this is why one of the main tank accidents is

the roll - inexperience drivers assume that because they have turned at

a particular angle on the flat, at a given speed, they can do the same

on a slope - nope they can't.) state of the ground you are moving over,

the quality of your brakes, the quality of your steering mechanism, do

you have a differential to switch extra power into the faster track (if

so how good is it?) - there are probably others.

I don't think you can extrapolate all turning circles from one set of

tank data. You can possibly get a formula but the parameters of that

formula would change from tank to tank because of the different

mechanical capabilities of their braking, steering, gearbox & power

systems (and the interrelationships of these - you may have a very

powerful tank that can apply a lot of power through a track but has a

crap steering linkage system or a tank that has low power but a

fantastic way of directing the power through to the track quickly.)

Which would be best? I am not a mechanic either, I haven't a clue - you

will have to talk to tank designers about this one!)

WW2 tanks cannot turn on the spot. There needs to be forward (or

rearward) motion. Without this there is no speed differential between

tracks and thus no turn can take place. This is a real bugger for non

turreted tank destroyers lurking in ambush. If an enemy appears 'out of

arc' the tank destroyer may well have to edge forward out of cover to be

able to fire at it (this means they must lurk with engines running, with

all the implications that has for overheating and engine smoke giving

away your position or they lurk with engines switched off and face the

prospect of trying to start whilst in action (not that easy) or

starting, backing out and abandoning a position, all because the enemy

are not straight ahead.)

There is also a minimum speed at which a turn can take place. Unless

sufficient power (and therefore forward or rearward motion) is applied

to pull the tank round obviously nothing happens. What tends to happen

in tight turns (e.g. street fighting turns) is that the driver slows to

a halt before the turn and applies power, a 'biting point' is reached

where power output suddenly overcomes the vehicle inertia / resistance

and the tank 'jerkily' slews round. This is often where the 'inside'

tank tracks come off - ripped off through sideways force. Or something

else gives (like the gearbox or power train). The driver has tried too

hard. He is trying to put the tank through a very tight turn and has

applied a lot of power to overcome both the weight of the tank and the

fact that he has got the brakes full on one side. It is much safer to

turn steadily at say 5 miles an hour, than to turn sharply at 2 mph. But

if you imagine turning steadily in a street fighting situation what

happens is that your turning arc brings you out into the centre of the

street and for a few seconds your vulnerable side armour is what the

enemy anti-tank gunner sees in front of him. If you can slew it round

without taking the track off then all he sees is your front armour.

Of course in very tight turns the length of the tank itself dictates

what a minimum arc can be.

I believe some WWII tanks could do the "neutral turn" number, but maybe not.

[76mm]

Well that answer seems rather definitive...thank you Tim Hughes!

[c3k]

Gents,

The translation of the German term was "zero radius turning gear". "Gear" referring to the actual gears in the transmission, as opposed to the looser definition of "gear" meaning "stuff".

The Tiger (I for sure, possible II) and the Panther are explicitly mentioned as having the zero radius turning ability. This is a "pivot in place" ability. This differed from the Allied tanks in that one track was driven forward while, simultaneously, the other track was reversed. Both tracks moved, which reduced or eliminated all the problems inherent in skidding one track. (Also, skidding one track still resulted in a lateral movement of the tank's center of mass.) The two tracks' speeds were synchronized such that the center of the tank pivoted over the same spot in the ground.

Obviously, the tactical payoff could be quite worth the high technical cost of such a capability.

Regards,

Ken

(Edited to clarify the differences in tank pivoting.)

[ June 19, 2006, 05:41 AM: Message edited by: c3k ]

[mav1]

Great info as always guys.

So how fast can modern tanks rotate?

And back to the 100mm soviet gun its only slightly heavier than the British 17pdr, so should it be rated heavy while the 17pdr is medium.

[Joachim]

On immobile guns:

Design choice by BFC. They considered some things to be impossible during the CM scope of a battle (which for most players is below 40 minutes). Their reason was that it was too complex to set up certain guns.

Italian 7.6 AA can't move, too - at least in CMAK. Guess there are others.

Grß

Joachim