Alternative History Armoured Fighting Vehicles Part 3
- Thread starter Claymore
- Start date
- Status
I agree with both posts above and think that a variety of AFV's would be developed just as they were in OTL WWII, some fast light armoured vehicles with semi-auto cannons(3.7's) might be developed and some long barreled highly accurate cannon armed tanks could be developed as well.
I can imagine a lightly armoured AFV like the Hellcat with a gun like that of the Panther's (KwK.42) on it and TD's like the Waffenträgers with large caliber guns mounted on them with decent armour but not very mobile.
AFV's in your scenario could be quite different from OTL but still have quite a few similarities some aspects.
No problemo. It looks like the WW1 Canadian gun truck - I have one of George Bradford‘s drawings of this, so will post it later. 👍
1) OTL Weapon #1: The Mias/Moras Tank was a Italian mobile shield/Infantry support weapon invented in 1935 with the concept of supporting advancing infantry.
- It had enough frontal armor to protect it from small arms and heavy machine gun fire.
- It could be armed with either two 6.5mm machine guns or a 45mm mortar that a 5 round autoloader/magazine.
- It could be crewed by one person.
- Unfortunately the motorcycle engine it used was under powered and there wasn't a seat for the operator, meaning you had to walk at a slow pace while using it, making you a sitting duck. It couldn't be used effectively in rough or heavy forested terrain either.
Ansaldo MIAS/MORAS 1935 - Tank Encyclopedia
The Ansaldo MIAS and MORAS were two motorized mobile shields designed with the lessons of the First World War in mind.tanks-encyclopedia.com
2) OTL Weapon #2: The Sd. Kfz. 2 aka "Kettenkrad was a German half-track motorcycle invented in 1939 for the use as a military utility tractor.
- Only needed a single operator.
- The front motorcycle wheel was optional, and could be steered just with the tracks.
- Top speed of 44mph and could pull some pretty heavy loads.
- Was only 3 feet wide, 4 feet tall, and about 8 feet long if you take off the motorcycle wheel, making it pretty small.
- Did relatively well in rough terrain.
Sd.Kfz. 2 - Wikipedia
en.wikipedia.org
3) ATL Weapon Design Idea: Let's say in 1943, the Italian Social Republic (German backed North Italian puppet state) decides to build itself a light, small, fast, and 1/2 man operated infantry support weapon in urban/mountainous environments by combining the Kettenkrad with Mias/Moras with some additional upgrades? If this were to happen, what design features would you guys suggest?
At work.
Ah, I sed some one else is pondering the possibilities of the 'Jagdenkrad'
All the very best (And hoping everyone has a great new year)
Cheers.
I never realized, but Pz II has a very unique and rare suspension type among prewar tanks: Independent leaf springs, instead of leaf spring bogies.
I don't know the characteristics of that setup sadly, but it should avoid the limitations of bogies, which are that they limit vertical travel and halve normal travel when one wheel is already compressed. Wish that had been done on early Pz IIIs and Pz IV instead of bogies.
Sadly, independent spring suspensions were very rare in that time period outside of some coil springs...
Looks surprisingly good:
I don't know the characteristics of that setup sadly, but it should avoid the limitations of bogies, which are that they limit vertical travel and halve normal travel when one wheel is already compressed. Wish that had been done on early Pz IIIs and Pz IV instead of bogies.
Sadly, independent spring suspensions were very rare in that time period outside of some coil springs...
Looks surprisingly good:
Last edited:
I was under the impression that preloading the second wheel on a bogey was an advantage, but I think the independent leafs does give you some more flexibility in the number and size of your running wheels, as well as being simpler and (debatably) more reliable than coils, but notably heavier unless I'm mistaken.
(a lot of caveats in that statement but I'm running entirely on memory so I've probably gotten something wrong.)
(a lot of caveats in that statement but I'm running entirely on memory so I've probably gotten something wrong.)
Yes, it's actually the opposite. When you preload a wheel then the second can't travel as much. In the case of the Chieftain for example the normal bump (or rebound not sure) travel is about 166mm but only 89mm if one wheel is preloaded. Independent suspensions don't have that issue at all.
They restrict spacing and occasionally the size of the wheels yes, depending on the configuration of the bogie. This also means the swingarms can't be very long, which is why vertical travel is lower than on individual suspensions. The entire frame of the bogie also adds a lot of weight.
From my understanding, bogies came from the influence of the railway industry in tank building. The only advantage they may offer is that you don't need to cut holes for the swingarm bearings but you need to drill holes for the bolts of the bogie itself so it's dubious. In theory you can also then put two swingarms on one spring and reduce the amount of high quality springs, but you don't need bogies for that and many bogie suspensions use two springs anyway.
From my understanding, bogies came from the influence of the railway industry in tank building. The only advantage they may offer is that you don't need to cut holes for the swingarm bearings but you need to drill holes for the bolts of the bogie itself so it's dubious. In theory you can also then put two swingarms on one spring and reduce the amount of high quality springs, but you don't need bogies for that and many bogie suspensions use two springs anyway.
Leaf springs are comparably heavier than coils and volute springs yes, which is rather problematic in tanks where every kg spent on the suspension is one not spent on armor or internal volume. The reason they were so common is that they were cheap, simple and already used a lot in the car industry, which was often used by leaf spring users for tank building. They also are quite limited in vertical travel because you would need to make them very long, and don't cope well with weight increases and weights beyond 30 tonnes.
They did have some advantages like having some dampening capability which was nice before shock absorbers became common, but they weren't the future.
Blade-type Volute springs (VVSS/HVSS) are the lightest IIRC, and they don't need guide rods like coils because they are quite stiff from side to side so they are quite simple to integrate. But they are very inefficient and have a lot of limitations for tank suspension, like the fact they are quite limited in length and therefore travel compared to coils. And they concentrate stresses which can make them less durable. American volute spring suspensions were very limited in travel.
Coil springs are probably the best in terms of maximum travel out of those 3 spring types but they require more bearings, a guide rod and often shock absorbers so they are more complex. But that's just an issue for developping them, not a nonstarter. Otherwise in individual form they are the best form of suspension prior to the appearance of torsion bars and hydropneumatic suspension.
The Germans actually tried independent coil springs on Leichttraktor and Pz IIIA but they abandonned too early, which led to the unsuccessful leaf spring bogie Pz IIIs. Kind of a missed opportunity there...
I'm also curious as to whether using springs with volute springs inside acting as bump stops would work. That would make for a clean self-contained unit.
They did have some advantages like having some dampening capability which was nice before shock absorbers became common, but they weren't the future.
Blade-type Volute springs (VVSS/HVSS) are the lightest IIRC, and they don't need guide rods like coils because they are quite stiff from side to side so they are quite simple to integrate. But they are very inefficient and have a lot of limitations for tank suspension, like the fact they are quite limited in length and therefore travel compared to coils. And they concentrate stresses which can make them less durable. American volute spring suspensions were very limited in travel.
Coil springs are probably the best in terms of maximum travel out of those 3 spring types but they require more bearings, a guide rod and often shock absorbers so they are more complex. But that's just an issue for developping them, not a nonstarter. Otherwise in individual form they are the best form of suspension prior to the appearance of torsion bars and hydropneumatic suspension.
The Germans actually tried independent coil springs on Leichttraktor and Pz IIIA but they abandonned too early, which led to the unsuccessful leaf spring bogie Pz IIIs. Kind of a missed opportunity there...
I'm also curious as to whether using springs with volute springs inside acting as bump stops would work. That would make for a clean self-contained unit.
marathag
Banned
Besides that advantage in cost and easy of manufacturing, leaf springs also add a degree of built in dampening, that doesn't exist with coils or torsion bars. So they need shock absorbers
Note that Volute Spring, spiral flat springs, used in US tanks, combine the best features of leafs and coils. Came from US development of heavy railroad cars, to support heavy loads while giving a smooth ride
marathag
Banned
More on the Volute spring, they are less likely to deform/deflect/buckle than coils, as well as have less overall length for same range of compression as coils.
They do not have less overall length for the same compression. And coilsprings have a guide rod to precisely prevent buckling, so that's not an advantage for volutes in the end. Volutes are merely a compromise, not ideal at all.
marathag
Banned
Everything has drawbacks, and advantages. Volutes don't need the extra guide rods or shock absorbers like coils. There was a Christie Coil suspension Sherman prototype, to get the same travel as VVSS, needed coils over twice as long as the volutes
May I ask for a source? The travel of the Christie suspension Sherman is not referenced anywhere in Hunnicutt or over available sources on it.
It seems unlikely to me, as increasing travel with volute springs requires not just increasing the length, but also the base diameter and the thickness which quickly leads to space issues, while for a coil you really only need to adjust length. A long enough volute may be so wide it cannot fit anymore or forces the tank to be wider overall.
On both British and Soviet tanks, the Christie suspension could offer nearly 400mm of total travel, nearly the level of a Panther. It would be weird for the Christie Sherman to be so much poorer. Of course bogies already limit travel but I've never heard of VVSS or HVSS exceeding 200mm of travel.
And yes, I said volutes don't absolutely need shock absorbers. HVSS still got some though, so why not go for a better type of spring and individual suspension with the same accessories? And in fact, the very long and wide volute springs that would be required to get Christie/Panther levels of travel would most likely need guide rods themselves anyway.
This discussion has been fascinating.
I want to thank you guys for telling me about this stuff, as I never really thought about suspension.
I want to thank you guys for telling me about this stuff, as I never really thought about suspension.
Automotive components are probably my favorite subject in tank design, and yet it never seemed to attract that much attention from engineers in reality, except in some places. That always surprised me when automotive performance is pretty much what decides how heavy and efficient your tank can afford to be for given mobility requirements.
The only country which seems to have shown a lot interest was the USSR, they were really hell-bent on making powertrains as space-efficient as possible. I remember they used ejection cooling on some tanks, something no one else ever did, to reduce cooling losses.
There was also a pretty interesting idea of using a turbo-driven fan to reduce cooling losses in turbocharged engines.
marathag
Banned
The T4 was the Convertible tank of the mid '30s
So you have similar wheel travel, and the size difference of the springs is obvious
Christie suspension is great but a nightmare to repair and takes up space inside the cabin.
Spring bogies are easy to replace in the field but have limited travel.
Torsion bar suspension is simple and maintenance-free but you can't have a floor escape hatch and when it breaks you can't fix it in the field.
Hydropneumatic suspension (like on the British Challenger) is easy to replace and requires little maintenance other than a regular topping-up.
Spring bogies are easy to replace in the field but have limited travel.
Torsion bar suspension is simple and maintenance-free but you can't have a floor escape hatch and when it breaks you can't fix it in the field.
Hydropneumatic suspension (like on the British Challenger) is easy to replace and requires little maintenance other than a regular topping-up.
Last edited:
- Status