Landships II

Those spuds/grousers are reasonably common on Mk V's. They appear similar to the ones fitted to Whippets. There is a close up of one fitted to the Bovington Mk II on this site but most of the timber inside is missing.

I think the louvers are being hidden by the angle of the photo. This also happens with this photo. The dark area could be mud or discolouration due to another cause. The area itself is not a regular shape. There is a rounded extension at the upper right of its area, the shape's upper edge slopes downwards, and the right edge slopes back towards the rear. I've attached a drawing to show what I mean.

P.S.: The IWM photo Q_009248.jpg has a grouser/spud visible in the upper right hand corner of the photo.

-- Edited by Mark Hansen at 00:08, 2006-06-20

Centurion wrote:

---

You say that these spuds are fairly common on Mk Vs but the shots you enclose appear to show two tanks both from the same section (there are 3 photos of J8 and I thenk that the others are possibly all J2. Do you have any others?

---

The tanks in those shots are I.8 (AWM photo nos. E03784, E03917), J18 (IWM photo no. Q_009248), J2 (AWM photo no. P00098.001), and two unidentified tanks (AWM photo nos. E04939 and P00743.016). The ditched tank (E04939) isn't J2; the tracks are not the same at the rear of the starboard horn and the background of the two shots is different (A fence in E04939 isn't visible in P00098.001 but should be if they are the same tank). The tank in E04939 also sits far deeper in the ground. So there are tanks from at least two different battalions and five different tanks.

P.S.: Plus your shot which is listed at the AWM as AWM photo no. H09412. Six different tanks.

P.P.S.: Unfortunately I don't have a photo of every single Mk V ever built at every point in it's career. Does anyone?

-- Edited by Mark Hansen at 03:29, 2006-06-20

-- Edited by Mark Hansen at 03:41, 2006-06-20

Mark Hansen wrote:

---

Centurion wrote: On the shot I have enclosed one can clearly see the suround of the vent area but NO LOUVRES. I enclose a shot of the same tank from a different angle. Again I've had to blow it up somewhat but you can clearly see the odd lower left hand section of the vent area where there appears to be a smaller vent. That's the same shot of the same tank from the same angle. There's a lot more digital artifacts (pixellation) in the second shot but it's the same one. The louvers line up to provide the appearance of a blank plate when the shot is taken from above the vent area as in the photo I linked to earlier in this post. P.S.: Here is another example. Two screenshots of the same tank. In the shot where the tank is climbing, the louvers are visible. In the next, they are (apparently) gone. What changes? The angle. The second shot is taken from below the level of the louvers and this is what makes them vanish.-- Edited by Mark Hansen at 03:53, 2006-06-20

---

Sorry can't buy that. In your second shot the vent area still shows as a dark area all of one shade. Here is the original shot of the tank in my question - one can definitely see a seconf oblong REGULAR area in the lower left hand corner that is different. If the effect was due to the louvres lining up this would vanish.

 

Mark Hansen wrote:

---

Centurion wrote: Sorry can't buy that. In your second shot the vent area still shows as a dark area all of one shade. Here is the original shot of the tank in my question - one can definitely see a seconf oblong REGULAR area in the lower left hand corner that is different. If the effect was due to the louvres lining up this would vanish.   So if your explanation is that the area has been filled in, why would anyone want to starve their radiator of airflow?

---

The starboard is the EXIT vent! After the air has passed over the radiator! One possible explanation might be that the air was being diverted into the body of the tank. That inset could also be a small fan assisted vent. We do know that airflow in MK V and V*s was inadequate (hence the introduction of the additional engine fan and rooftop vent). This could be part of other attempts to deal with the problem. Just to even further muddy the waters I have found a very clear picture of a Port (Input) vent with canvas flaps over the louvres between the mud flaps - now that would have reduced radiator flow. However its 11.10 here now so I'll scan and post this tomorrow.

Mark Hansen wrote:

---

 Exit air which is HOT! Why would you feed HOT air into an already hot tank?? Remember to have airflow, there must be an intake and an outlet or you don't get any airflow through the tank in the first place. As you point out, the airflow was inadequate anyway. I reiterate: why would anyone want to slow down the airflow? To produce a mobile oven??

---

Just like in the Mks I,II,III and IV all of which fan drew air from the rear of the tank over the radiator and on into the body of the tank. It may not have been a very clever idea but it seems to have been better than the system on the Mk V and Mk V*. Possibly in desperation some one was trying to revert to the original system. Or as I said in my previous posting that inset square was another powered fan. More info is needed before jumping to conclusions. With regard to blocking airflow I enclose the picture of a Mk V port vent with canvas flaps over the louvres - anything no matter how crazy seems possible!
BTW the Medium B seems to have a similar side to side system as the Mk V and its engine also overheated so that the screws on the sparking plugs expanded and jammed in the cylinder block. If in the heat (sic) of battle the plugs oiled up one had to  stop the engine for an hour or so to cool down before the plugs could be changed! Tritton very wisely did not use the system on the Medium C and it was dropped on the Mk V** and the Mk VII (the latter apparently reverting to the Mk IV arrangement.)

Centurion wrote:

---

Just like in the Mks I,II,III and IV all of which fan drew air from the rear of the tank over the radiator and on into the body of the tank. It may not have been a very clever idea but it seems to have been better than the system on the Mk V and Mk V*

---

Are you sure the airflow was in that direction? Because at least on the Mk IV, you now have a system which guarantees CO poisoning! The exhaust pipe ends right next to the vents. In fact the end of the pipe is angled toward the vents!! If it's drawing air into the tank, then almost pure exhaust is going directly to the crew. Not a very clever idea? More like a mobile suicide booth.

P.S.: One more photo to add which shows the exhaust fumes being pushed away from the tank. If air was being dragged into the vents, the fumes should also be going into the tank. The photo is on the Landships site here.

P.P.S.: Just to make sure of the airflow direction I contacted David Fletcher. The air definitely did exit the Mk I - IV at the rear vents instead of entering.

-- Edited by Mark Hansen at 04:53, 2006-06-22

-- Edited by Mark Hansen at 14:30, 2006-06-22

Centurion wrote:

---

With regard to blocking airflow I enclose the picture of a Mk V port vent with canvas flaps over the louvres - anything no matter how crazy seems possible!

---

I think I may have the reason for those canvas flaps being there. They might have been fitted to reduce the temperature of the air going into the tank through evaporative cooling.

For those unfamiliar with the principle; when water evaporates, it reduces the temperature of the air that evaporates it. If you hang a curtain of thin material that is wet in front of a fan, it will provide better cooling than a bare fan.

This may have been an attempt to give a source of cooler air to the radiator and reduce the temperature inside the tank (world's first A/C tank?).

Problems with this method:

1. It probably wouldn't have been very successful seeing as how the volume of air entering the tank would have been relatively low anyway.


2. Water. Another problem would have been keeping the water up to the canvas. It only works while the canvas is wet; if it's dry, it won't help at all. I can't imagine anyone wanting to exit the tank in the middle of the battle to pour water over canvas flaps.


3. Mud. If the flaps get dirty, there won't be as much airflow and therefore not as much evaporation.


4. Humidity (1). If the outside air is humid, your evaporation rate drops and so does your cooling.


5. Humidity (2). The air entering the tank is water laden. Not good for metal parts of the tank.

That photo has been bugging me for days! On the face of it, you have something which slows down airflow which is the last thing you want. Then I remembered the bush fridge (No, it's not a political statement!). It consists of a frame which has cloth walls. Keep the walls wet and the breeze evaporates the water, keeping the contents cool or at least cooler than they otherwise would be.

Of course, this is just a theory but it does explain the canvas flaps and it fits in nicely with "anything no matter how crazy seems possible!" !

Evaporation cooling is an clever idea but I suspect that the water would evaporate very quickly giving a very short lived effect

The tank is indeed on a flat car (being shipped across Russia) so Roger's idea has more merit but I wonder why the easier approach of just putting a piece of canvas across the whole vent would not have been applied. Also no real attempt seems to have been made to seal anything else off (although the 6 pdr may have a canvas tampon cover). I have seen photos of this period where a sheet of canvas has just been drapped over the rear and side of the tank this protecting both sets of vents.

With regard to the 'sealed' starboard vent discussed earlier in this thread it has ocured to me that if the the starboard vent  was blocked and the rotation of the drum fan reversed then air would be drawn down from the front of the tank and sucked through the radiator, through the ducting, across the fan and out through the port vent (there was no ducting between the radiator and the starboard vents as the drive chain was in the way). Very like in the MK IV if you substitute rear for port.

I''ve been trying to sort out how air flowed in MK IV and earlier marks. There is very little hard info available. It would seem probable that in the MK IV it was from front to rear but I have seen it sugested that this was only introduced on the Mk IV (possibly by reversing the fan blades) and on earlier marks the others the opposite flow applied. This would make sense given the introduction of the exhaust pipes on the Mk IV as Mark has pointed out. It should be remembered that there was no ducting on tanks pre Mk V and the radiator was positioned on the starboard side so that much of the air sucked in by the fan would not pass over it whatever the direction of flow. When the exhaust was vented out through holes in the roof a front to back air flow would tend to suck some of it straight back into the tank. One way to check on this would be to se if the Lewis gunners on MK II and Mk IIIs had the same problem of air being sucked back through their  gun's cooling tube into their faces (carrying cordite fumes, hot air dust etc as did Lewis gunners on the Mk IVs (a rear to front air flow would actuall carry the gun fumes away). Any info anyone

Centurion wrote:

---

I''ve been trying to sort out how air flowed in MK IV and earlier marks. There is very little hard info available. It would seem probable that in the MK IV it was from front to rear but I have seen it sugested that this was only introduced on the Mk IV (possibly by reversing the fan blades) and on earlier marks the others the opposite flow applied. This would make sense given the introduction of the exhaust pipes on the Mk IV as Mark has pointed out. It should be remembered that there was no ducting on tanks pre Mk V and the radiator was positioned on the starboard side so that much of the air sucked in by the fan would not pass over it whatever the direction of flow. When the exhaust was vented out through holes in the roof a front to back air flow would tend to suck some of it straight back into the tank. One way to check on this would be to se if the Lewis gunners on MK II and Mk IIIs had the same problem of air being sucked back through their  gun's cooling tube into their faces (carrying cordite fumes, hot air dust etc as did Lewis gunners on the Mk IVs (a rear to front air flow would actuall carry the gun fumes away). Any info anyone

---

In the email I received from David Fletcher he made no distinction between airflow direction in a Mk IV and earlier Mk's. It would seem more logical for the air to flow from front to back on all of them because you still have the radiator to cool down. If the airflow is going from back to front on the Mk I - III then the radiator is heating up the air inside the tank and making conditions worse.

Centurion wrote:

---

It seems that non of the airflow options ,whilst the crew shared the cmpartment with the engine and radiator, was terribly good.

---

And who can argue with that?

The radiator: Are you sure it was on the starboard side rather than the center? The door at the rear of the tank was on the starboard side and from the photo in "British Mark I Tank 1916" p. 12, there was no obstruction from the gear position to the rear of the tank. The cutaway diagram in the same book also shows the radiator located behind the differential. This would make more sense with the vents being on the starboard side. Obviously the vents couldn't be located in the center (optimal position) due to the hydraulic ram of the Mk I and the design of the rear plate wasn't changed until the Mk V.

P.S.: That should be the vents being on the port side. Must learn to distinguish left from right!

-- Edited by Mark Hansen at 12:51, 2006-07-04