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Proposal for a new prototype German medium tank in tier VIII or IX


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WinG_HU #1 Posted 17 June 2013 - 12:26 PM

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(I used the search to find any topics with the word Borgward, but no matches. So I apologize if this has been discussed before.)

So. Almost every article about the development of the Leopard 1 MBT mentions that there were 3 different designs made by 3 different groups for the new German tank project. One was made by Porsche ("Group A", they won), the other was by Rheinmetall ("Group B") and the last one, which is always described as a futuristic project which never reached prototype stage, was designed by Borgward ("Group C").

I made some research about the last one and luckily I found some useful intel about it (luckily, because the proposed design was considered lost for a long time, and has only been found recently among the archives of Borgward). It was indeed a very unique-looking tank and I'm not surprised that it was never realized IRL.

So ladies and gents, please welcome Borgward's proposed design for the new German MBT of the 1960s.

Posted Image

Borgward was a German automobile manufacturer founded by Carl F. W. Borgward (November 10, 1890-July 28, 1963). The company was based in Bremen. The Borgward group eventually produced four brands of cars: Borgward, Hansa, Goliath and Lloyd. (Wiki)

The first thing one can notice is the lack of a conservative turret. (It is somewhat similar to the canceled Russian T-95 project almost 40 years later.) The unmanned turret suggests some kind of remote control. The design sports a very low silhouette and a slow size in general. The armor was probably paper-thin - as it was usual that time -, which means it had a low weight and it would have been very maneuverable.

Posted Image

The suspension is practically a modified-upgraded Christie suspension. Very unusual for the time, it was able to move without the tracks, only on wheels. The other models (as can be seen on the other pictures), use "normal" torsion bar suspensions.

I found some more info about this prototype on a German-language site, however I have no idea how trustful it is.

So basically, the concept of the Borgward prototype was very unusual and years ahead of its time. But the time that would have been necessary to bring all untested parts to technical maturity led to the cancellation of the project by the Ministry of Defence.

Features of the project:
- Moving with and without tracks
- Five double wheels with pneumatic tires (all bullet-proof)
(four driven, three steered)
- Hydro-pneumatic suspension with variable ground clearance
- Four water-cooled 6 cylinder - multi-fuel - boxer engines
(4 x 12 liter capacity, total power: 1100 kW / 1500 hp)
- Continuously variable hydrostatic steering gear
- Electro-hydraulical shift gears - Vmax: 80 km/h or 120 km/h without tracks
- Fuel tanks made ​​of rubber (?)
- 3-axis stabilized hydraulic turret with fixed 105mm cannon

That's all I could find about this extraordinary tank. I think it would a very nice second option for the "Leopard" medium line for Tier IX next to the Leopard PT A (by the way, the "A" means Group A, so it could be Leopard PT C or Borgward Prototype).

Some more pics:

Posted Image

Model of the Borgward prototype.

Posted Image

Some dude who found the original, 20 kg Borgward model among the archives of the factory.

Edited by WinG_HU, 17 June 2013 - 12:33 PM.


aGentleTanker #2 Posted 17 June 2013 - 12:38 PM

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The model looks like as it wouldn't have any gun depression, the technical drawing looks more promising regarding that.

WinG_HU #3 Posted 17 June 2013 - 12:40 PM

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View PostaGentleTanker, on 17 June 2013 - 12:38 PM, said:

The model looks like as it wouldn't have any gun depression, the technical drawing looks more promising regarding that.

I think the gun depression could have been enhanced by the variable ground clearance. Not the fastest solution, though.

Conte_Vincero #4 Posted 17 June 2013 - 12:48 PM

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- Fuel tanks made ​​of rubber (?)
That presumably refers to the rubber self sealing fuel tanks used on aircraft, it has a vulcanised rubber interior, and a non vulcanised rubber exterior that will swell up when wet, blocking small holes.

Also do you have information on the crew, The gun looks like it is autoloaded. If it isn't then does the turret have limited traverse? The only crew positions seem to be behind it and so they would have trouble loading if the gun was traversed to the side. Also what gun is that? If you know, then it should be possible to find if there was a planned autoloader for it.

EDIT: also the plans show a commander's cupola with an aiming periscope that isn't present on the model. That would seem to suggest limited traverse.

Edited by Conte_Vincero, 17 June 2013 - 12:50 PM.


WinG_HU #5 Posted 17 June 2013 - 12:52 PM

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View PostConte_Vincero, on 17 June 2013 - 12:48 PM, said:

- Fuel tanks made ​​of rubber (?)
That presumably refers to the rubber self sealing fuel tanks used on aircraft, it has a vulcanised rubber interior, and a non vulcanised rubber exterior that will swell up when wet, blocking small holes.

Also do you have information on the crew, The gun looks like it is autoloaded. If it isn't then does the turret have limited traverse? The only crew positions seem to be behind it and so they would have trouble loading if the gun was traversed to the side. Also what gun is that? If you know, then it should be possible to find if there was a planned autoloader for it.

Ah, thanks for the explanation.

The gun is very probably the 105mm Royal Ordnance L7A3, just like Leo1's gun. The use of autoloader is also probable considering the small size. I dno if there is more info about this tank as it was cancelled before the prototype stage, so only blueprints exist. I will do some research later.

Conte_Vincero #6 Posted 17 June 2013 - 01:14 PM

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View PostWinG_HU, on 17 June 2013 - 12:52 PM, said:

Ah, thanks for the explanation.

The gun is very probably the 105mm Royal Ordnance L7A3, just like Leo1's gun. The use of autoloader is also probable considering the small size. I dno if there is more info about this tank as it was cancelled before the prototype stage, so only blueprints exist. I will do some research later.
Thanks, out of interest, could you do a higher quality version of the plans, While they are scarce on detail about the drive system (not enough room, no cooling or final drive etc.) or crew (where the heck do they fit). They do have serious detail on the hydraulic system and turret. Also I can't read the dimensions on the plans from here.

EDIT: Done a bit of research, the engines are quite possibly from the original Porshe 911 (either that or he planned to develop new ones from scratch which seems a bit stupid, and if so why would he not just design one big one) That would give just under 520HP (although that would change with the modifications for being tank engines) The transmission is also quite possibly the most stupidly complex I've ever seen. I don't know where the 12 litre capacity figure is coming from and my suggestion would be Bogward's **** as 4 engines that size would NOT fit

Edited by Conte_Vincero, 17 June 2013 - 01:42 PM.


WinG_HU #7 Posted 17 June 2013 - 01:35 PM

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View PostConte_Vincero, on 17 June 2013 - 01:14 PM, said:

Thanks, out of interest, could you do a higher quality version of the plans, While they are scarce on detail about the drive system (not enough room, no cooling or final drive etc.) or crew (where the heck do they fit). They do have serious detail on the hydraulic system and turret. Also I can't read the dimensions on the plans from here.

You'll like this, then. However, I found no further info on the Borgward page.

Posted Image

Conte_Vincero #8 Posted 17 June 2013 - 03:25 PM

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Thanks, I'll print those out and have a look at them to see what I find

WinG_HU #9 Posted 18 June 2013 - 09:54 AM

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View PostConte_Vincero, on 17 June 2013 - 03:25 PM, said:

Thanks, I'll print those out and have a look at them to see what I find

If you find anything, don't hesitate to post it here.

Conte_Vincero #10 Posted 18 June 2013 - 01:46 PM

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View PostWinG_HU, on 18 June 2013 - 09:54 AM, said:

If you find anything, don't hesitate to post it here.
Sadly I ran out of time writing stuff up at home, so will have to finish it when I get home. Went through the whole aero engine section of Jane's looking to see if its engines were aero derived, and couldn't find anything. Did some measurements, and the armour is ~80mm thick at the point of the hull. Also there is no way a driver could fit in front of the turret.

Edited by Conte_Vincero, 18 June 2013 - 01:46 PM.


Conte_Vincero #11 Posted 18 June 2013 - 11:35 PM

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Engineering analysis of the Borgward tank, Please note that most of this is speculation on my part, based on my engineering knowledge. If is not to be taken as gospel, especially if it conflicts with established fact. With that aside, enjoy the wall of text
Spoiler                     


CaptianNemo #12 Posted 28 June 2013 - 11:22 PM

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I believe the engines are referred to as a Twin-Six. which is 2 inline six cylinder engines geared together, eventually, to a single output  shaft. Such setups were used in the 1920s one such company was Sunbeam and another, iiirc, Packard, which used them until they eventually developed V12 engines which were more complicated to cast at the time. iirc one of the companies kept the name Twin-Six to describe the V12s but I can't recall which I would have to look. It's been about 2-3- years and I'll look it up in my books.

Another reason to use the inline 6 was the fact that they had the in line 6 already in mass production and it was cheaper to develop the gearbox to connect them then to build a new engine from scratch. Plus parts commonality also helped cut costs. IE between regular inline 6 production and the Twin-Six setup. Besides costs it was a easy/complicated way to get more horsepower with limited development/expense.

Commander center
Gunner on the left
Driver on the right.

Also on the upper first drawing is that a 2ed gun/cannon on the left of the main gun?

The transmission looks like power can be transferred from one side to the other and back so steering should be fine.

What intrigues me is the space between the engines and the ammo storage in the turret as well as the space above the transmission.The space about the transmission I could see being used for fuel. And since it is a blank in between the engines and ammo you could stuff a driver in there. Well since the model didn't have anything to suggest it I guess ignore that part. However that range finder on the turret is interesting. The whole thing is a bit odd.Also the wheel counts are off between the model and the drawing. 8 for model and 7 for drawing.

NEMO.

Edited by CaptianNemo, 28 June 2013 - 11:44 PM.


Conte_Vincero #13 Posted 29 June 2013 - 09:52 AM

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View PostCaptianNemo, on 28 June 2013 - 11:22 PM, said:

I believe the engines are referred to as a Twin-Six. which is 2 inline six cylinder engines geared together, eventually, to a single output  shaft. Such setups were used in the 1920s one such company was Sunbeam and another, iiirc, Packard, which used them until they eventually developed V12 engines which were more complicated to cast at the time. iirc one of the companies kept the name Twin-Six to describe the V12s but I can't recall which I would have to look. It's been about 2-3- years and I'll look it up in my books.

Another reason to use the inline 6 was the fact that they had the in line 6 already in mass production and it was cheaper to develop the gearbox to connect them then to build a new engine from scratch. Plus parts commonality also helped cut costs. IE between regular inline 6 production and the Twin-Six setup. Besides costs it was a easy/complicated way to get more horsepower with limited development/expense.
What intrigues me is the space between the engines and the ammo storage in the turret as well as the space above the transmission.The space about the transmission I could see being used for fuel. And since it is a blank in between the engines and ammo you could stuff a driver in there. Well since the model didn't have anything to suggest it I guess ignore that part. However that range finder on the turret is interesting. The whole thing is a bit odd.Also the wheel counts are off between the model and the drawing. 8 for model and 7 for drawing.

NEMO.
I don't think the engines are twin flat 6s. If you look at the plans, you can make out the cylinders and there are 3 total in each bank, so they'd have to be twin straight 3s. While there are a few people producing 3 cylinder engines they are a fairly modern trend and I don't think that there are any total in each bank.

That space intrigues me as well. I assumed that it was space for a driver, but I measured it and it's only 1.2m by 1.07m, I fit in that, but only when sitting flat on the floor, and not pointing my feet forward. It is possible that there could be a driver in there, but he wouldn't get a seat. (Yes I have just spent 5 mins sitting on the floor with a tape measure) I'm guessing fuel and hydraulic fluid goes in there.

A bit odd doesn't even begin to cover this tank, I hadn't actually noticed the road wheel disparity  :amazed: , but it does seem like this was sketched on the back of an envelope, and then someone tried to do detail design on it.

CaptianNemo #14 Posted 30 June 2013 - 03:09 AM

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The inline 6 was used as an example of what previous people had done and why.

Now that I look at it again, if the upper image is like the rest of the drawing then the engine seen is just one of 4. and if so this really weird. Why? Because its an opposed 6 cylinder engine with 3 on each bank 180 degrees apart.  4 of these engines in total. So, 24 cylinders... Which would give it the horsepower to move but how do you transfer that much torque to the drive wheels...

Vertical opposed 6 cylinder engines seems like a bad idea and I think they could have figured something better out then this...

The drawing sure makes it look like a solid block. And the drawing are similar to other opposed designs. Except this is vertical rather then horizontal ie flat or with the cylinders arranged up and down.  Both of which are used in light airplanes.

Posted Image
Usually opposed means this...

Posted Image
Posted Image
Source: http://www.ww2incolo...t-4389-p-2.html

http://i10.photobuck...olbenDiesel.jpg
Its a bigger photo...^^^

and they arrange the engine to fire the cylinders in an vertical up and down fashion where the piston heads are facing each other OR and pointed both up and down with a crank in the middle.

I am trying to guess at the size of the cylinders on the engines. But it is hard because using the 105mm gun that you came up with gave me rather large pistons, to me, and that does not seem right.

I tried to find the bore and stroke of the Tigers I engine and for the love of me cant locate it at the moment just to see what it is and give me an idea of what it could be on this tank.

However all this being said this is what it would look like. This is a Franklin 6 cylinder engine mounted in a helicopter.
Posted ImagePosted Image

http://blog.seattlep...cout-in-detail/
More photos here. Also a water cooled version was made for the Tucker automobile.

Edited by CaptianNemo, 30 June 2013 - 03:31 AM.


Conte_Vincero #15 Posted 30 June 2013 - 03:25 PM

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Check diagram again, the cylinders aren't vertically opposed, the cylinders are horizontally opposed, but stacked vertically. Also, provided that the engine is direct injection, it doesn't matter if it's vertically opposed anyway, as shown by the fact that the Junkers 205 you posted was an immensely successfully engine. According to the stats given each engine is a 12 litre engine, which puts each cylinder at 2 litre capacity. As I mentioned earlier, I have detailed technical information on every Second World War aircraft engine, and went through all of them to look for candidates. As far as I remember the Kinner O-552 is the largest at 9 litres. If you include vertically opposed engines, then the closest is the Jumo 205, but that is too old and too big (16 litres). Flat engines have been very popluar in sports cars, as they are lighter then other low capacity engines, which leads me to conclude that he simply wanted to scale up a roadcar engine.

CaptianNemo #16 Posted 01 July 2013 - 05:14 AM

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ok ok a vertical stack of horizontally opposed cylinders.

12 litres each? x 4 is a bit much... 48 liters total...

But 12 liters in total does not sound right at all...

The Tiger I is only 21 liters.

Sounds even more odd the more I think about it.
Just think of the mass at the front of the tank.\
And trying to stop the tank.

Edited by CaptianNemo, 01 July 2013 - 05:15 AM.


Harim #17 Posted 01 July 2013 - 03:19 PM

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Why not? WoT is full of total fantasy tanks, which were neverever planned or built, let's do it... but wait, this is the european forum, that mean nobody cares about this forum... so u wasted your time, WG devs don't care in any about non-russian-speaking players.

Conte_Vincero #18 Posted 01 July 2013 - 03:48 PM

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View PostCaptianNemo, on 01 July 2013 - 05:14 AM, said:

ok ok a vertical stack of horizontally opposed cylinders.

12 litres each? x 4 is a bit much... 48 liters total...

But 12 liters in total does not sound right at all...

The Tiger I is only 21 liters.

Sounds even more odd the more I think about it.
Just think of the mass at the front of the tank.\
And trying to stop the tank.
Oh it's completely odd, as I said in my analysis, this is just about the only way you could cram that amount of engine into the front of tank, but it would be impossible to cool. The weight distribution will be a bit front heavy, but as there is no armour (25mm) then that might possibly be manageable. I'd be interested to see the suspension calculations for this. Brakes will be fine though. There is no armour or turret, so weight will be kept down.

View PostHarim, on 01 July 2013 - 03:19 PM, said:


Why not? WoT is full of total fantasy tanks, which were neverever planned or built, let's do it... but wait, this is the european forum, that mean nobody cares about this forum... so u wasted your time, WG devs don't care in any about non-russian-speaking players.
I agree, this would make a nice ELC style tank, with the fast acceleration and limited traverse turret. If we replace the fantasy engines with a conventional HL 295 Ausf Ahnenerbe then all should be good.

Edited by Conte_Vincero, 01 July 2013 - 03:51 PM.


CaptianNemo #19 Posted 02 July 2013 - 03:21 PM

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1500hp/4 = 375.

http://www.aerofiles.com/motors.html

Been digging through the lists to find something close and I did see this...

Continental
Tiara 8-380, Tiara 8-450, O-540 1970 -380-450hp 541.3ci 6HOA.
GTSIO-520 19?? = 340-435hp 6HOA.
Voyager 550, OL-550 1990 = 300-400hp 552ci 6HOA

Lycoming
O-540
1957 = 235-380hp 541.5ci 6HOA. Prefixes: AEIO, HIO, IGO, IGSO, IO, IVO, LTIO, TIO, VO.Posted Image
O-541 1965 = 310-450hp 541.5ci 6HOA. Prefixes: TIO, TIGO.Posted Image
O-580 1948 = 320-375hp 578ci 6HOA. Prefixes: IO, GSO, SO.


It would seem that getting the horsepower is not an issue. But locating something big enough, that is still 6 cylinders, is a bit difficult.

NEMO.

Edited by CaptianNemo, 02 July 2013 - 03:37 PM.


WinG_HU #20 Posted 11 July 2013 - 03:00 PM

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It was a pleasure to read your reasoning, dudes. Anyway, SerB (leading dev or something) said that this tank can indeed make it into the game.




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