Oh dear, Dave won't be happy. You've highlighted some of the major issues in FF&S CPR gun design!!
Yes, the reload time always was screwed. Dunno what the reason was for using MJ for so many things in FF&S, but it gave results that aren't even in the ballpark of reality. Most of us houserule it. Or, if you mainly use ETC autocannon like me it isn't an issue because autocannon use a different design sequence.
We could go through the other major issues as we did on a thread a few years back. Such as the penetration of the advanced rounds (APFSDSCI, etc) getting crazy good at high TLs (houserule that too, thanks Rupert Boelyn wherever you are now). The fact that the tracked suspension always makes AFVs too heavy. The fact that receivers and bipods for firearms are wildly overweight (MJ problem again). The way streamlining a grav craft doesn't give you sloped armour (seems to assume you still have a box) so you have to pay volume twice if you want a streamlined, sloped armour grav vehicle. The fact that the turret volume rules for vehicles seem to be more concerned with the amount of space required outside the vehicle to turn the turret without hitting anything than the actual volume of the turret. The missing scale efficiencies for powerplants. And so on.
Despite all that - I still think it is one of the best single RPG books I've ever seen. The scale of the challenge it takes up, and the closeness within which it comes of pulling it all off is breathtaking.
--- In , Master Uxi <master.uxi@...> wrote:
>
> Redesigned this as part of the CPR sequence for doing the M1 Abrams series
> of MBT
>
> Some thoughts that have occurred to me over the years (and this time in
> particular):
>
> Ammo is pretty far off and should probably be more detailed. Rather simple
> assumption, regardless of type. The table should adjust for materials and
> intent, as well as just TL. For example, 120mm ammunition if I'm reading
> right is 30kg regardless if it's APFSDS, AFSDSDU, HEAT (HEAP, etc). Real
> Life ... or even Wikipedia. much less my FM-17-12 (aka 3-20) tells us the
> M829 sabot variants ranged from 18.6 to 22.3kg depending on the propellant
> and density of the DU penetrator as well as details like metal vs carbon
> fiber sabots, etc.
>
> Loading times and crew requirements don't seem to fit my experience or
> understanding of our own MBT. I don't consider the Abrams to have
> mechanical assist, for example, and default timing is one 5-second combat
> round per MJ. In the standard crewman skills test, the deadline is 7
> seconds for the 120mm and my manual says 5 seconds for the 105mm. In the
> Fleet, a loader is gonna kicked if he can't do it in 4-5 seconds which is
> about the minimum for the hydraulic door to open enough to grab the round.
> The crew requirements might work for indirect fire as it is, though and
> would also either be a human loader or an autoloader. Almost ironic that
> NATO used human loaders and Warsaw Pact nations used mechanical
> autoloaders given their doctrines on man vs machine.
>
> The time/power discrepancy actually seems to be somewhat proportional to
> the MJ difference, which has a natural correlation to the size and thus
> weight of the round at the MJ calculated (8.85MJ for the M256 vs 6.90MJ for
> the M68/L7 105mm). Realistically, the proper time to load should be a
> function of the size of the round and the strength of the loader and
> experience and familiarity with the task. In a skill system like TNE,
> basic Task Failure would be accomplished in the speed of the MJ while basic
> success would just beat it by exactly 2 seconds each. Outstanding success
> would double that by shaving 4 seconds giving realistic times. Critical
> failure would mean damaging the round, possible causing misfire or perhaps
> striking the combustible case and releasing propellant in the turret! Ref
> discretion. There, that nit is picked with my House Rule.
>
> The Abrams uses safety features that actually slow down the loading, though
> increases crew safety. Lap-loading (holding a round in the lap while
> waiting for command), etc could be much faster and while I hear it was SOP
> in the old days with the M60 but that was before blow-off panels, etc.
> Soviet autoloaders are SLOW (they max elevate to eject the round) but one
> 5-second round per MJ still sounds excessive. 2 seconds per MJ rounded up
> to the nearest whole combat round is more reasonable for autoloaders. Most
> Soviet/former-Soviet designed tanks are going to take 2-3 rounds or so
> which is between 150-200% the time a NATO meatbag loader not messing it up
> is going to take . Not sure what the thought process was for this design
> sequence. I imagine it's indirect fire but maybe Dave can elaborate.
> anyhoo:
>
> *M256 Cannon / Rheinmetall 120mm L/44*
> TL8
> 528cm Long (120/44 caliber)
> Laser Rangefinder (LRF)
> Optical Rangefinder (GAS)
> TL8 Digital Ballistic Computer
> Direct Mount
> No options
> 8.85 MJ muzzle energy
> Crew: 2
> Range: KE 494m / HE 370m
> Reloading: 9 rounds* [1-2 rounds per Skill/Task roll]
> Volume: 2.0204 m3
> Mass: 2.0204 tonnes
> Price: 0.048 MCr
>
> *Ammunition*
> APFSDSDU (M829)
> TL8
> 12cm
> Damage: 26
> Burst: nil
> Penetration: Short: 145, Med: 135, Long:125, Extreme: 105
> Price: 900 Cr
>
> HEAP (HEAT M830)
> TL8
> 12cm
> Damage: 16
> Burst: 29
> Penetration: 113C
> Price:450 Cr
>
Yes, the reload time always was screwed. Dunno what the reason was for using MJ for so many things in FF&S, but it gave results that aren't even in the ballpark of reality. Most of us houserule it. Or, if you mainly use ETC autocannon like me it isn't an issue because autocannon use a different design sequence.
We could go through the other major issues as we did on a thread a few years back. Such as the penetration of the advanced rounds (APFSDSCI, etc) getting crazy good at high TLs (houserule that too, thanks Rupert Boelyn wherever you are now). The fact that the tracked suspension always makes AFVs too heavy. The fact that receivers and bipods for firearms are wildly overweight (MJ problem again). The way streamlining a grav craft doesn't give you sloped armour (seems to assume you still have a box) so you have to pay volume twice if you want a streamlined, sloped armour grav vehicle. The fact that the turret volume rules for vehicles seem to be more concerned with the amount of space required outside the vehicle to turn the turret without hitting anything than the actual volume of the turret. The missing scale efficiencies for powerplants. And so on.
Despite all that - I still think it is one of the best single RPG books I've ever seen. The scale of the challenge it takes up, and the closeness within which it comes of pulling it all off is breathtaking.
--- In , Master Uxi <master.uxi@...> wrote:
>
> Redesigned this as part of the CPR sequence for doing the M1 Abrams series
> of MBT
>
> Some thoughts that have occurred to me over the years (and this time in
> particular):
>
> Ammo is pretty far off and should probably be more detailed. Rather simple
> assumption, regardless of type. The table should adjust for materials and
> intent, as well as just TL. For example, 120mm ammunition if I'm reading
> right is 30kg regardless if it's APFSDS, AFSDSDU, HEAT (HEAP, etc). Real
> Life ... or even Wikipedia. much less my FM-17-12 (aka 3-20) tells us the
> M829 sabot variants ranged from 18.6 to 22.3kg depending on the propellant
> and density of the DU penetrator as well as details like metal vs carbon
> fiber sabots, etc.
>
> Loading times and crew requirements don't seem to fit my experience or
> understanding of our own MBT. I don't consider the Abrams to have
> mechanical assist, for example, and default timing is one 5-second combat
> round per MJ. In the standard crewman skills test, the deadline is 7
> seconds for the 120mm and my manual says 5 seconds for the 105mm. In the
> Fleet, a loader is gonna kicked if he can't do it in 4-5 seconds which is
> about the minimum for the hydraulic door to open enough to grab the round.
> The crew requirements might work for indirect fire as it is, though and
> would also either be a human loader or an autoloader. Almost ironic that
> NATO used human loaders and Warsaw Pact nations used mechanical
> autoloaders given their doctrines on man vs machine.
>
> The time/power discrepancy actually seems to be somewhat proportional to
> the MJ difference, which has a natural correlation to the size and thus
> weight of the round at the MJ calculated (8.85MJ for the M256 vs 6.90MJ for
> the M68/L7 105mm). Realistically, the proper time to load should be a
> function of the size of the round and the strength of the loader and
> experience and familiarity with the task. In a skill system like TNE,
> basic Task Failure would be accomplished in the speed of the MJ while basic
> success would just beat it by exactly 2 seconds each. Outstanding success
> would double that by shaving 4 seconds giving realistic times. Critical
> failure would mean damaging the round, possible causing misfire or perhaps
> striking the combustible case and releasing propellant in the turret! Ref
> discretion. There, that nit is picked with my House Rule.
>
> The Abrams uses safety features that actually slow down the loading, though
> increases crew safety. Lap-loading (holding a round in the lap while
> waiting for command), etc could be much faster and while I hear it was SOP
> in the old days with the M60 but that was before blow-off panels, etc.
> Soviet autoloaders are SLOW (they max elevate to eject the round) but one
> 5-second round per MJ still sounds excessive. 2 seconds per MJ rounded up
> to the nearest whole combat round is more reasonable for autoloaders. Most
> Soviet/former-Soviet designed tanks are going to take 2-3 rounds or so
> which is between 150-200% the time a NATO meatbag loader not messing it up
> is going to take . Not sure what the thought process was for this design
> sequence. I imagine it's indirect fire but maybe Dave can elaborate.
> anyhoo:
>
> *M256 Cannon / Rheinmetall 120mm L/44*
> TL8
> 528cm Long (120/44 caliber)
> Laser Rangefinder (LRF)
> Optical Rangefinder (GAS)
> TL8 Digital Ballistic Computer
> Direct Mount
> No options
> 8.85 MJ muzzle energy
> Crew: 2
> Range: KE 494m / HE 370m
> Reloading: 9 rounds* [1-2 rounds per Skill/Task roll]
> Volume: 2.0204 m3
> Mass: 2.0204 tonnes
> Price: 0.048 MCr
>
> *Ammunition*
> APFSDSDU (M829)
> TL8
> 12cm
> Damage: 26
> Burst: nil
> Penetration: Short: 145, Med: 135, Long:125, Extreme: 105
> Price: 900 Cr
>
> HEAP (HEAT M830)
> TL8
> 12cm
> Damage: 16
> Burst: 29
> Penetration: 113C
> Price:450 Cr
>