In the first half of 1939, the British decided that they were going to improve
upon the A13 Cruiser Christie tanks that were then in production.
The result was a very sleek-looking Covenanter, the A13 Mark 3.
To boost production in this critical time of need, the Ministry of Supply
went to Lord Nuffield of Nuffield Mechanization and Aero Company
and asked them to join in the production contracts.
Lord Nuffield said “no”,
and in a manner perhaps reminiscent of that of North American Aviation
when they were asked by the British to build P-40s,
said “but I will do better.
I will build you a tank of my own design that is better than your tank”.
Well, being kind of hard up for tanks,
the Ministry of Supply acceded to this request,
and so began the development of the Cruiser A15, the Cruiser Mark 6.
Later on, it was given the name Crusader,
and it became an iconic tank of the desert war.
Welcome back to the tank museum in Bovington,
and the tour of their Crusader Mark 3.
Inside the Chieftain’s Hatch
Now, before we continue,
I’d better explain the case of measles that this tank has developed.
They are 3D scanning it, and we came along
we kicked the scanning crew off so we could make this film.
However we were not sufficiently cruel to ask them
to remove all those individual dots and then put them back on again.
Anyway, back to the story.
Nuffield decided, in the interest of expediency,
to start with the basis of the earlier A13.
This shaved sufficient time off the development process
that the first Crusaders arrived for testing in April of 1940,
about a month and a half before the first Covenanter arrived.
Crusader 1 was a five man crew with a 2-pounder gun,
three men in the turret, a driver,
and a bow gunner in a suicidally small turret on the front left corner:
this was quickly deleted.
Now, the 2-pounder may have been a fantastic gun in 1939,
but it was becoming obvious that this gun was going very rapidly out of style.
Now, the good news was
that the British had actually designed the 6-pounder before the war.
The bad news was
that they didn't see the point in spending the money to produce any,
and after Dunkirk happened,
well, they couldn't afford to stop producing 2-pounders
long enough to retool for the 6-pounder.
Thus, it wasn't until 1941 that production of the 6-pounder
entered full swing, and it was December of ‘41
before the decision was made to design a tank to put the gun into.
Crusader Mark 3, the 6-pounder version,
entered production in summer of ’42, which places it on the timeline
somewhere in between the M3 and M4 American mediums,
if you want to make a comparison, a little bit closer to the M4.
The tank is of a composite construction:
The idea was that they were going to have a soft steel interior
that could be welded without affecting the integrity of the metal
and then have the armour plate added on top of that,
but in the end they just stuck with riveting anyway.
The overall weight of the tank was supposed to be kept to 18 tons—
the limit of army bridging at the time,
whilst maintaining about a four centimeters equivalency of armor.
This means that your typical plate is not much over 20 millimeters.
Indeed the nearly horizontal upper slope here is only about 9 millimeters,
but it does get reasonably thicker to about 30
for the driver's box with the soft steel interior.
Components on the front… Well, a marker light.
The track tensioning,
it looks like they stole an idea from the Soviet T-34, you go through here,
and it appears to be a worm drive for the idler at the front.
Lifting eye, mount for a towing clevis.
The headlights now come with brush guards
to protect against going through trees and bushes,
whatever else you feel like you can just run over.
As you go a little bit further forward, you'll see the driver's hood.
He's got a couple of ports, one is for vision,
the other one is actually a pistol port,
just in case he is feeling particularly courageous.
They extended the hull a little bit to fit the improved Liberty engine,
and this allowed the installation of a fifth road wheel pair.
The road wheels, well they were originally made of aluminium, or aluminum.
Interestingly, the history of that word,
apparently it's one of the few words Americans get right.
But regardless, aluminium was of high value for aircraft manufacturers,
so they eventually changed to pressed steel.
The suspension is of the Christie type, of course,
and this means that the springs are located
sandwiched in between an outer and inner plate of armor,
which is highly inconvenient for two reasons.
A) you're taking up space, so the interior volume of this tank
is not as wide as the outside dimensions might indicate.
Secondly, if you have to get at one of these springs,
you're in for some serious work.
Because you have to remove the tracks, you've got to remove the wheels,
you then have to remove the side skirts and the bins,
they're all bolted together,
and then finally you can get at the armor plate and pull that off.
As I say, highly inconvenient.
There is ample stowage as you move up on the sponson bins,
and there's an additional small bin on the turret rear,
and on the right hand side of the turret you will see a spot light.
Things at the back of the tank.
Well, you are going to notice that attached to the towing hook at the rear
is a rota-trailer, and we will come back to that one a little later.
You'll also see a mounting point for an axillary fuel tank,
it's about thirty Imperial gallons,
that was especially if you didn't want to tow a rota-trailer, for whatever reason.
On the left hand side, you're going to see a filler port down at the bottom
for the final drive lubrication system, and what I can only assume
is a “what were they thinking?” moment on the right rear.
And of course, there is one on the far side as well.
What you are looking at here is the air cleaner system.
The filter is here, the intake is here.
Well it's actually three of them per side.
Now, if you're going to try to deliberately come up
with a spot on the tank that is most likely to receive dust and dirt,
I think you would do very hard to come up with a better place
than directly above the track at the back, because imagine this tank
is trundling along at about 30 miles an hour in the desert,
and dust is coming up…
Well anybody who’s driven a convertible realizes
that as a wind block moves forward, it creates a vacuum,
which is then filled by a vortex,
which comes back so there is actually wind going forwards
directly behind the vehicle, not backwards.
And of course this is going forwards right into the air intakes.
What were they thinking?
The back deck, nice and flat.
I'm standing on top of the Wilson epicyclic steering system.
A little bit further forward under this hatch is the Liberty Mk 3.
This is a derivative of the World War 1 tank engine,
it's a V12 27litre, puts out a reasonable 340 horsepower,
this will push the tank, which is now 19 tons,
along at a 27 mile an hour clip, which is pretty good,
especially when you consider that the Christie suspension
will allow it to maintain a good speed off-road.
The catch is that the Liberty isn't so much of an engine block
as it is a whole bunch of cylinders bolted together,
and over time the vibrations would start to work the parts loose.
Add to that further problems; for example sand
getting into the cooling system would affect the white metal parts,
the radiator fans… well their drive was always unreliable.
This has got the chain system, later they moved to a shaft.
As a result of all this,
the tank did not exactly establish a reputation for reliability.
As you move outboard, there’s a fuel tank
for about a 110 gallons (Imperial, of course) of petrol,
and this was estimated to get the tank to about a hundred miles on roads.
A little bit inboard of that you can just see the two angled radiator fans.
Finally, I am going to go back to the rota-trailer.
Now, I can't do any better at explaining this thing
than David Fletcher did during Operation Think Tank back in about 2012.
So that said, I'll hand over the video to him and I'll see you on the next one.
I'm going to change gears here, and go on to
what I know has got to be your favorite subject ever,
given I have heard you speak with great passion
about your opinion on this device: the rota-trailer.
Where did that come from?
I mean, it sounds like a good idea to begin with,
we've all seen M4s towing extra ammunition,
and of course, there's nothing wrong with towing fuel behind
because that's what the Sherman Crocodile did.
So why does the rota-trailer have such a place in your heart?
It’s absolutely useless.
To put it in perspective to begin with,
I firmly believe that no tank should ever be expected to pull a trailer.
It is asking for trouble, and going backwards is a nightmare.
But among all these things, the rota-trailer is an exception,
it is totally useless, pulled or pushed in any direction.
If you've never come across one or ever seen one,
it's a metal box with no springs (oh, you wouldn’t want springs)
and the container that the box consists of
has compartments for ammunition, one compartment for a fuel pump,
and the wheels, which have solid rubber tires on them,
are hemispherical discs that you fill with fuel.
So you tow this thing behind your tank, you've got fuel,
you've got a pump to pump the fuel into the tank,
and you've got ammunition bouncing about in this lovely metal box.
They have three problems with it.
First of all, the wheels leak,
so just when you need it, there's no gas left in the wheels.
Secondly, because it has no springs,
it bounces over every stone or rut it can find
until the ammunition is so bent and battered you can't use it,
and they said the worst thing of all
was after a while it would bounce three or four times and turn upside down.
That would twist the rod that was holding it on to the tank,
make it nearly impossible to detach it,
so you've now not only crippled the tank,
it's got nothing to move with or fight with,
so yeah that's my favorite reason for hating them if you like.
Incidentally, I met an elderly American officer at Bovington a few years ago,
and he belonged to a unit, which was an Anglo-American unit.
And what they done was they trolled the army for farm boys,
and the idea was that these guys would go over
in the wake of the invasion forces and get the harvest in.
They obviously didn't know the French,
because they were already out there plowing and harvesting,
while the battles going on, more or less,
but these guys were issued with rota-trailers
to go with their tractors to give them fuel,
but that's the only account I've ever heard of anyone actually
being issued with them and for a while,
having never had to test them, actually liking them.