Tell me about...the Hypervelocity Autocannons

[Alan Grant]

I am a little intrigued by these, especially the combo of range and damage potential of the Hypervelocity AC-10. I'm curious what others think of them. I'm considering mounting the HVAC-10 as the main weapon in a heavy tank.

[Ian Sharpe]

Aren't those the ones that blow up on a roll of 2?  Just take an LB-10. 

[Diablo48]

I would say no on the 10 in general.  Even ignoring the extra 5 points of heat generation because you are looking at a tank, when compared to the 10-X you are paying another 3 tons, the risk of explosions, reduced ammo count, and the ability to fire cluster rounds for an additional two hexes of max range (short and medium are the same).  I just cannot see any way that is justifiable next to the other options you could use.  You are only one ton short of a full Gauss Rifle at that point, and if you are really that tight on mass you can just downgrade to a 10-X and toss a LRM 5 with a ton of ammo in the 3 tons you get back for improved performance.

The 2 and 5 are slightly more justifiable because they get into the stupid long ranges category, but even so you are probably better off with Extended LRMs which are more efficient at range at the cost of an enormous 10 hex minimum range band.

[martian]

I am a little intrigued by these, especially the combo of range and damage potential of the Hypervelocity AC-10. I'm curious what others think of them. I'm considering mounting the HVAC-10 as the main weapon in a heavy tank.

Actually, there is one heavy tank using HVAC-10. It's Po Tank upgrade from TRO: Prototypes.

I could disregard weight, less ammo, etc., but that spontaneous explosion just "kills it". Ultracannons can get jammed, but this ...

Just imagine you have a battalion of tanks, your tanks start firing, enemy is not even in range of his guns - and the number of your tanks is being reduced by one, round after round ...

[Moonsword]

I am a little intrigued by these, especially the combo of range and damage potential of the Hypervelocity AC-10. I'm curious what others think of them. I'm considering mounting the HVAC-10 as the main weapon in a heavy tank.

Take a look at the HVAC/10.  Now take a look at the Gauss rifle, which does 50% more damage at a longer range for one ton more.  On ASFs and 'Mechs, which have to deal with the HVAC's heat, the HVAC/10 frequently winds up as the heavier weapon once you account for the heat sinks.  If you don't want to find the one ton it takes to go Gauss or the minimum range isn't acceptable in this situation, save some tonnage and go for the LB 10-X or even an Ultra/10.  Neither one explodes just from pulling the trigger.

The HVAC/5 does manage to out-range the LGR and lacks the minimum.  The LGR still does 60% more damage and lacks the HVAC/5's charming self-immolation habit.  It's also competing with the mid-weight ELRM launchers, which generate a lot of heat, need more ammo, and have a heinous minimum range but are significantly superior in the sniper category as well as being able to be fired indirectly.  If you're not looking for a sniping weapon, the LB 10-X is slightly lighter albeit much bulkier.

HVAC/2s are less objectionable, being lighter and doing less damage on a fumbled roll as well as having a truly great range.  However, because they have a much longer reach and more ammo per ton, you'll probably fire them more often, too, so they're arguably more likely to explode than at least the HVAC/10 is.  At this size and for their primary role, they're competing directly with the ELRM 5, which is lighter but does more heat and has that 10 hex minimum range to worry about.  This is the one HVAC that doesn't make me automatically start looking for spare parts to replace it with.

[Prince of Darkness]

Moonsword got it to me.  There really is no reason to mount one over a gauss rifle, even despite the "interesting" side effect of the smoke that is generated from it's firing.

[MoneyLovinOgre4Hire]

HVACs have such heavy disadvantages that I've sometimes wondered if the in-universe design was actually done as an act of sabotage by the FedSuns (since they're listed as having been developed by the Capellan Confederation).

[YingJanshi]

What about in-universe cost? Aren't the rather cheaper than Gauss Rifles or ERLMs?

[MoneyLovinOgre4Hire]

ERLRM 5s are cheaper than any of the HVACs, but HVAC ammo is exponentially cheaper than ERLRM ammo.

[Moonsword]

What about in-universe cost? Aren't the rather cheaper than Gauss Rifles or ERLMs?

Gauss rifles are 300k.  HVAC/10s are 230k.  Both have 20k C-Bill ammo lots.  (For the record, the LB 10-X is actually more expensive than either one, commanding a price of 400k C-Bills.)  Considering the difference in performance, that's a price I'm willing to pay and I expect a lot of other people would be willing to fork over a little under a 1/3 increase in price for a 50% jump in damage and better range.  On a per point basis, Gauss rifles are actually slightly cheaper at 20k C-Bills per point of damage, HVAC/10s running to 23k.  Admittedly, you can't cut the numbers quite that efficiently in-universe but the fact that Gauss rifles are headcappers and HVAC/10s aren't is going to be readily apparent.

It's even cheaper when you remember that an HVAC has a vastly higher chance of catastrophically misfiring and requiring replacement.  In most vehicles, that's going to be replacement of the entire tank.  Gauss rifles will do more damage if they're hit while charged, no question about that, but in my experience, it's more common for a Gauss rifle to roll a 2 than it is for it to eat a crit.  Keep in mind that unlike Gauss ammo, HVAC ammo is still explosive, and unlike Gauss rifles, HVAC ammo will explode due to overheating like any other kind of AC ammo will.

HVAC/5s are cheaper compared to LGRs, which are quite pricey for what they do but the same survivability calculations are in play.  I think the incidence of explosive misfires is still going to give the LGR the edge here.

[MoneyLovinOgre4Hire]

Since HVACs use Advanced Rules to begin with (smoke), any comparison between them and Gauss Rifles should also consider the Advanced Gauss Rifle shutdown rules, which make Gauss Rifles a lot safer.

[Moonsword]

Yeah, that's going to have an impact as well.

[SCC]

If a tank like the Po has a HVAC-10 in its turret and the gun goes up, is the tank truly destroyed?

[MoneyLovinOgre4Hire]

Probably not, that's a 10 point explosion to the Turret location, IIRC, and the Po HV is fairly durable: it's got 21 points of Hardened Armor in the turret.  But it is going to be more or less out of the battle at that point.

[Alan Grant]

How is this explosion factor handled? Is it like a crit? Something making it an armored component might mitigate a little?

Really just sating my own curiosity at this point. The news that the thing can blow up killed the idea of using one.    #P

[Maelwys]

Its an internal explosion equal to the damage value of the weapon. So that 10 point explosion is going to blow the turret off the Po. Atleast as far as I know.

Kind of makes the 21 points of Hardened Armor amusing, considering you're just as likely to simply blow your top from shooting the gun.

[MoneyLovinOgre4Hire]

As the Po HV does not appear to mount CASE, yeah, if the HVAC explodes it's going to pop the turret right off the tank.

Which creates a rather amusing mental image, as well as turning the crew into spaghetti sauce.  ;D

[Diablo48]

As the Po HV does not appear to mount CASE, yeah, if the HVAC explodes it's going to pop the turret right off the tank.

Which creates a rather amusing mental image, as well as turning the crew into spaghetti sauce.  ;D

Ok, I really have to wonder what idiot thought that combination was a good idea.  It is bad enough to mount a weapon that could randomly kill the tank during normal use, but not including CASE when you do it is just unbelievable.  No one in their right mind would ever agree to climb into that deathtrap, much less ride it into combat.

[MoneyLovinOgre4Hire]

It's Capellan.

[YingJanshi]

It's Capellan.

And what's that supposed to mean?

[MoneyLovinOgre4Hire]

It's probably built as a punishment.

[Headshot]

And what's that supposed to mean?

Simple, "It's Capellan" is the logical, believable, understandable and even correct answer to "Who in their right mind would ever agree to climb into that deathtrap, much less ride it into combat?"   ;D


On the HVAC, its an obvious dead-end technology. I'd rather take a standard AC with special ammo, or a UAC of whatever size fits, and thats while i loathe the Ultras below 20.
I usually try to replace the UAC-10 with a Gauss Rifle as fast as i can (ENF-6M is a nice example), and the HVAC-10 is even a ton heavier.
My prefered autocannon on tanks is the UAC-20 btw. Massive damage, and you can just ignore the 16 heat. Feels almost like cheating.

[ScannerError]

The HVAC-10 might have been acceptable if it was around in the old L1 days, competing against the AC 10, PPC, and AC/20 as a main gun.  Once L2 tech hits, the 10 is junk.  I'm still annoyed by the HVAC Po's design, though at least it's easy to swap the HVAC for an AC 20 to make a brutal cityfighting version. 

The HVAC-5 has a tiny niche, and the LGR is a very healthy alternative.  Only real advantage it has is the bit of extra range. 

The HVAC-2 has extreme range with a tiny minimum range, though it competes with the ELRM 5.  8 tons for 2 damage is a poor rate of return, but it does have a role.  Surprisingly fun to take a few Scorpions (nobody cares about them anyway) and refit them with these, then have the smoke from the firing obscure a LRM carrier or two.   Doesn't even destroy the turret on a 2.  Not the most optimal (some smoke SRMs from an SRM carrier would probably be a better idea), but it works.   The range lets it do AA duty as well, and a lithobraking is just as lethal when it comes from a HVAC hit. 

I think that the HVAC was intentionally gimped compared to other weapons, as there's just so few ways to actually use them.  The always-there explosion chance is horrible.  If they could at least use the standard AC alternate ammo they'd have a decent (if still explosive) niche, but as they cant... 

[Ryumyo]

I like the HVAC-2. Especially when paired up with ELRMs for the effect of using the AC as a "spotter rifle" and following up with massive amounts of missles. Sort of how tank guns work, co-axial MG " to-hit " then main barrel " 'da pain ".

[Nav_Alpha]

Simple, "It's Capellan" is the logical, believable, understandable and even correct answer to "Who in their right mind would ever agree to climb into that deathtrap, much less ride it into combat?"   ;D

Actually... Pretty much any tank crewman ever... They breed us short, stocky and stupid...

Seriously though, the HV/10 just doesn't seem worth it.

From memory, are the Ice Hellions obsessed with them? I seem to remember them having a lot of mechs mounting them.

[MoneyLovinOgre4Hire]

No, HVACs are IS only tech and the Hellions were wiped out before the guns attracted any significant attention.  You might be thinking of HAGs.

[glitterboy2098]

question.. does the HVAC have a lower technology rating than a guass rifle?

one would imagine that what is basically a supercharged autocannon would be simpler to build than a guass rifle. the Confederation had been suffering from industrial issues prior to Xin Sheng due to a combination of half their infrastructure being in davion hands, and much of the rest horribly mismanaged due to a couple generations of crazy rulers. so it would make sense if the CC chose to focus more on developing the tech they could produce to new heights, rather than try to get actual intelligent infrastructure improvements past Romano. even after the CC retook much of what they lost, during the team up with the FWL in 3057, they wouldn't have been able to immediately utilize what they regained.

[Nav_Alpha]

No, HVACs are IS only tech and the Hellions were wiped out before the guns attracted any significant attention.  You might be thinking of HAGs.

Ah! You're right! Sorry

[Kotetsu]

Since the HV ACs appear to have first shown up in Maximum Tech, it is possible they started designing the weapons, but once they got access to more reliable weaponry they set the idea aside. Then the Jihad happened. And since everyone was throwing everything they could into production, and the Capellan military tends to both not care about their men, and a slightly psychotic, the weaponry was rushed into service. Whether they stay in service or are reduced to niche roles remains to be seen.

As for me, I'm willing to put anything into testing at least once or twice... And the extreme range on the HVAC 2 makes me slightly giddy.

Then again, I have created what amounts to super-JagerMechs, loaded with nothing but Class-2 autocannons before. The ones wielding RACs have... extremely nasty "death by papercut" possibilities.

[Martius]

I was surprised how much fun the HVAC 2 can be.

Used a Dreadnought MKII and its mix of HVACs and ERLMs  helped me to immobilize/mission kill my opponent's vee long before they came into range.

The class 5 I found less useful and I never would take the class 10 but the 2... yeah. I like it somehow.