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38 minutes ago, Lord_James said:

 

No offense, but I don’t trust you as much as some of the other people on this forum; they have proven their knowledge. So, I’m gonna have to ask for a second opinion. 

 

@N-L-M, @Toxn, any confirmation on what I did wrong? 

 

BUT!, your response does make sense, and I probably should have considered that. 

 

 

Yeah, I just checked and I think I mis-clicked a button on my calculator, but it’s 113mm LoS (80mm / cos45 = 113.1), which is 1.13 decimeters. Multiplied to 1.1 gives me 1.24. I’ll make some corrections when I have time. 

What's your array design? I'll happily double-check it for you.

 

BUT, as we saw earlier, you shouldn't trust my numbers either...

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I'll get to it mathing them out in a few hours.

Note that the armor numbers are tuned for warheads below 200mm dia; for larger weapons the light armors would lose some of their dynamic effects (thicker more robust jets wouldnt be as affected by light flyer plates), and there ideally should also be a gradual loss of dynamic effects for successive layers (once a jet is destabilized, theres diminishing returns for destabilizing it further); these factors were however excluded for the sake of not overly complicating the equations, as the reference threats are all within reasonable limits.

 

Also @Lord_Jamesthe air gap is multiplicative, so you need to take the exponent, ie for 13 cm the factor is 1.1^1.3=1.13.

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10 hours ago, Lord_James said:

 

No offense, but I don’t trust you as much as some of the other people on this forum; they have proven their knowledge. So, I’m gonna have to ask for a second opinion. 

 

@N-L-M, @Toxn, any confirmation on what I did wrong? 

 

BUT!, your response does make sense, and I probably should have considered that. 

Thats fine, i dont have a military background so dont trust anything i write.

 

But review this doc.  https://www.researchgate.net/publication/242230270_MULTIPLE_CROSSWISE_ORIENTATED_NERA-PANELS_AGAINST_SHAPED_CHARGE_WARHEADS

 

When i backcalculate the Various k1s for their nera (after including a 390- 490mm space effect) i got

First nera k1 = 3.3

Standard Follow up nera k1 = 1.1

Alternate follow up nera k1 = 1.6

 

That was for a 3/5/3 nera

 

Anyway, point is that the norman turret upgrade is a good example of how to make these calcs work.  Outer layer is ERA, on a vertical surface, chevron stye.  Inner layer is NERA with a horzontal aspect to its lay.   NERA calcs are for the optimal single nera cassette that gets stacked to maintain coverage.

 

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Ok, just remade my upper right array, AGAIN, and re calculated both completed arrays: 

 

Lower Front: 

1206mm CE 

635mm KE 

 

Front Right: 

1177mm CE 

625mm KE 

 

For CE, K1 was 2 for the first group, and 1.1 for the second group. KE was 1.05 for the first group and 1.0 for the second. 

 

Both arrays can withstand Deserent 60/105 ATR and any known AP (125mm included) currently used by Cascadia, from ~30o from the front (the mock up of my side array is giving these numbers, but they're not finalized yet). Unfortunately, that BGM-1 is a monster, so an upgrade kit will most definitely be required to survive a hit from those. 

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5 hours ago, Lord_James said:

remade my upper right array, AGAIN, and re calculated both completed arrays: 

Post or PM the new layout for checking please.

I'll be running the numbers on the arrays you posted soon

 

EDIT: ran the numbers, both arrays you posted in the last page are good for 500mm KE and BGM-1 at horizontal impact.

 

Also, I would like to remind participants that armor and structure are typically 50-55% of the overall vehicle's weight, with 60% being a practical limit for working reliable vehicles.

The remaining weight distribution is approximately as follows:
15% suspension
10% tracks
10% drivetrain
5% weaponry
2% assorted systems
1% crew
1% ammo
1% fuel
Or so.

There are minor variations possible, but kindly try and keep things reasonable.

This of course means that for a 120 ton vehicle, at most only approximately 72 tons will be armor and structure (both turret and hull), keep that in mind while planning vehicle weights.

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Question re spaced armour and engines

 

A compartment for an engine is 1500mm,  kharkov 5TD

 

For a nominal 1000mm CE the calcs are

1500/100 = 15

1000/(1.1 to power 15) =  240mm CE 

 

So, as long as precursor charge is already dealt with, the engine bay reduces CE by 75%.  Hmmm, rear of my tank may be tougher than the front?

Edited by Kal

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2 hours ago, Kal said:

Question re spaced armour and engines

 

A compartment for an engine is 1500mm,  kharkov 5TD

 

For a nominal 1000mm CE the calcs are

1500/100 = 15

1000/(1.1 to power 15) =  240mm CE 

 

So, as long as precursor charge is already dealt with, the engine bay reduces CE by 75%.  Hmmm, rear of my tank may be tougher than the front?

It's actually better than that, because equipment has a TE in this competition.

 

But on the other hand, check the requirements - crew survival is third. Think very carefully how wrecking the tank to save the crew will work if your primary task is to keep on fighting and just replace dead crewmen as necessary.

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Proposed tank design has dual Kharkov engines at back, so a hit to one will not necessarily disable the other. But wow, 1500mm of space does wonders to CE.

 

I would wager that its a lot quicker to replace a motor (kept as a field spare) than to rewire/rehose a fighting compartment.   And probably cheaper too.

 

In the automotive world a car's wiring harness is a higher cost item than the engine, its probably the same in tanks also.  This is a 1960s tank, not a 1940s tank.

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@N-L-M

 

U7URAAw.png

 

From left to right (all at 60o unless otherwise stated): 

 

35mm RHA 

61.5mm air 

20mm HHA 

127.5mm NERA-L (71o)

28.5mm RHA 

36mm Glass Textolite 

127.5mm NERA-L (71o)

50mm JPA at 1.16 TE 

 

For my calculations, I used the full K1 value for the first set of NERA, and then 1.1 for the second set. 

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2 hours ago, Lord_James said:

@N-L-M

 

U7URAAw.png

 

From left to right (all at 60o unless otherwise stated): 

 

35mm RHA 

61.5mm air 

20mm HHA 

127.5mm NERA-L (71o)

28.5mm RHA 

36mm Glass Textolite 

127.5mm NERA-L (71o)

50mm JPA at 1.16 TE 

 

For my calculations, I used the full K1 value for the first set of NERA, and then 1.1 for the second set. 

I had to rough out the calculations a bit due to how I laid out my own calculating spreadsheet, but it looks like it will fit the bill and then some.

 

It's also monumentally thick and heavy ;)

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3 hours ago, Kal said:

Proposed tank design has dual Kharkov engines at back, so a hit to one will not necessarily disable the other. But wow, 1500mm of space does wonders to CE.

 

I would wager that its a lot quicker to replace a motor (kept as a field spare) than to rewire/rehose a fighting compartment.   And probably cheaper too.

 

In the automotive world a car's wiring harness is a higher cost item than the engine, its probably the same in tanks also.  This is a 1960s tank, not a 1940s tank.

Fair enough. We already have a few engine-first designs, and if you're willing to make one with, say, the transmission at the back and the engines up front you'd get a lot of protective bang for your buck.

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15 hours ago, Toxn said:

the transmission at the back and the engines up front

Gotta have a good way of not having the driveshaft(s) be a hazard in the case of an underbelly blast, though.

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3 hours ago, N-L-M said:

Gotta have a good way of not having the driveshaft(s) be a hazard in the case of an underbelly blast, though.

Put it in an armoured housing running along the hull side opposite the driver and just resign yourself to being a bit wider and taller than you need to be...

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21 hours ago, Kal said:

Proposed tank design has dual Kharkov engines at back, so a hit to one will not necessarily disable the other. But wow, 1500mm of space does wonders to CE.

 

I would wager that its a lot quicker to replace a motor (kept as a field spare) than to rewire/rehose a fighting compartment.   And probably cheaper too.

 

In the automotive world a car's wiring harness is a higher cost item than the engine, its probably the same in tanks also.  This is a 1960s tank, not a 1940s tank.

Planes pretty much too.I remember that Mig-21 had wiring made manual, plus it wasn't color coded, so people from the factory had to come with the original documents on the wiring to help in wiring matters on airfields.

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On ‎4‎/‎9‎/‎2019 at 5:21 PM, Toxn said:

So I think I just T-72'd myself.

 

The backup is looking really, really good.

 

Edit: really, really, really good

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Nfpvlfl.jpg

It developed from the same philosophy that informed the Big Buoy tank concept, so it's been provisionally dubbed 'Lil Buoy after the pre-war mythological figure.

 

So far the weight estimates have it at 71mt fully loaded, with the same 133mm gun and stretched AVDS-derived engine as the Brick (2950kg dry mass, 1205HP). This gives it a power-to-weight ratio of just under 17HP/mt, which should bump it over the minimum requirements in that department. It also has the same autoloader setup as the Brick, with 20 complete rounds in left side of the turret and another 10 in the left front ammo rack. If needed, the turret crew can now manually serve the gun (although this would obviously only be in case of emergencies or malfunctions).

 

The gun itself fires AP-FS, HE-FS and various types of HEAT-FS. The AP-FS can comfortably exceed the new penetration requirements, to the extent that it can penetrate the turret armour of a Norman-series tank from the front at 2000m.

 

133mm ammunition:

  • Common: seperate propellant and warhead stages, semi-combustible cases. The propellant stage is 150x1000mm and has a steel case stub. The warhead stage is 133x1000mm bottlenecked to 150mm at the base. Warhead stages may have extra propellant.
  • AP-FS: 34kg, 960m/s, 265mm RHA penetration at 2000m (130mm BR-482B used as reference)
  • HE-FS: 35kg, 835m/s, ~45-50mm RHA penetration
  • HEAT-FS (single, steel cone): 35kg, 835m/s, 430mm RHA penetration
  • HEAT-FS (tandem, copper cone, improved explosives and pressing, higher cone precision, wave shaper, improved detonators etc): 35kg, 835m/s, 230/615mm RHA penetration

Slight update on the 'Lil Bouy design:

RJdb1BB.jpg

The commander's MG has been replaced with a better-looking gun on a cupola ring. In terms of more practical changes, the armour has been beefed up for LIC and urban combat. The all-up weight is now up to 74.5 mt, but in return lower hull sides are immune to 105mm guns and tandem RPG warheads from up to 45 degrees off the front. The turret front has been thickened with arrowhead arrays containing an HHA skin, NERA elements and air gaps, which should make it even tougher against Cascadian 120mm guns and ATGMs (+215mm KE, +460mm CE), air gap variable and thus not factored in). The mantlet has been similarly upgraded (+227mm KE, +940mm CE).

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1 hour ago, N-L-M said:

What's the armor weight fraction?

It was around 50%, but there have been a few revisions since I first calculated everything.

 

I'm going to recalculate and hopefully drop some weight...

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59 minutes ago, Datengineerwill said:

What are the range and/or combat ready requirments for the LIC and HIC respectively?

Range of at least a couple hundred km is recommended but theres no hard limit.

What do you mean by combat ready requirements?

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3 minutes ago, N-L-M said:

Range of at least a couple hundred km is recommended but theres no hard limit.

What do you mean by combat ready requirements?

For example travel 200km @ X speed then sit and defend (or wait in a combat ready state) for X hours before needing to refuel.

 

Maybe that's called combat day requirements?

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