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BattleTech Player Boards => Fan Designs and Rules => Aerospace => Topic started by: Lagrange on 04 November 2021, 20:26:11

Title: The Workhorse Universal Heavy ASF
Post by: Lagrange on 04 November 2021, 20:26:11
I've been tinkering with heavy ASF designs trying to find something that is reusable in many different roles as part of a force design exercise in conjunction with a LAM (https://bg.battletech.com/forums/battlemechs/lams-as-the-missing-link-in-dropship-elimination/) and Battle Armor (https://bg.battletech.com/forums/battle-armor/most-capable-marines/).  I've been tweaking a bit since mentioning this in an earlier post---here's my current candidate.  Any suggestions for how to improve?  Additional roles that could/should/can't be fulfilled?

The ASF is rather unlike the other units since it can support omni configurations.  Taking advantage of that, it seems we can satisfy several very different roles---Cargo, basic fighter, high speed engagement fighter, ground support, a mixed role ground/fighter, infantry insertion, and marine insertion.  The primary drawback of all these configurations is transport weight, hence weapons are shared across several configurations.

The C (Cargo) configuration is a baseline with 3 tons of fuel and 40 tons of cargo capacity.  In places with rich fuel, this is a fairly reasonable short-range ferry.  This is straightforward except that it's interesting to note that between the internal bomb bay and hardpoints, this could be used to launch 6 Alamo missiles.
Code: [Select]
Workhorse C (Cargo)

Mass: 100 tons
Frame: Unknown
Power Plant: 300 Fusion
Armor: Heavy Ferro-Aluminum
Armament:
     40.0 tons of pod space
Manufacturer: Unknown
     Primary Factory: Unknown
Communication System: Unknown
Targeting & Tracking System: Unknown
Introduction Year: 3145
Tech Rating/Availability: E/X-X-X-D
Cost: 7,334,250 C-bills

Overview
Quirks: Easy to Maintain (1), Internal Bomb Bay (3), Improved Life Support(1), Rumble Seat(0), Bad reputation (-1), Poor Targeting[Short](-2), No Ejection (-2)

Type: 5/8 Workhorse C (Cargo)
Technology Base: Inner Sphere (Standard)
Tonnage: 100
Battle Value: 2,106

Equipment                                          Mass
Engine                        300 Fusion             19
Safe Thrust: 5
Max Thrust: 8
Structural Integrity:         10                     
Heat Sinks:                   10 [20]                 0
Fuel:                         240                   3.0
Cockpit                                               3
Armor Factor (Heavy Ferro)    694                    35

                           Armor 
                           Value 
     Nose                   208   
     Wings                170/170 
     Aft                    146   

Fixed Equipment
None

Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
Cargo (40 tons)         FSLG      40.0     -      -    -    -    - 

The F configuration is a general fighter configuration.  The ERPPC+capacitor and Gauss Rifle provide a significant long range punch while the blanket of small lasers provides point defense, close in attack, and some modest tail guns for a dog fight. All of this is fairly routine, except for the relatively heavy armor which implies it can fight much longer than many other ASF.
Code: [Select]
Workhorse F (Fighter)
Cost: 9,205,313 C-bills
Battle Value: 3,324
Heat Sinks:                   15 [30]                 5
Fuel:                         400                   5.0

Weapons
and Ammo                Location   Tonnage  Heat   SRV  MRV  LRV  ERV
Gauss Rifle               NOS       15.0     1     15   15   15    0 
PPC Capacitor             NOS       1.0      -      -    -    -    - 
2 Small Laser             NOS       1.0      1      3    0    0    0 
ER PPC                    NOS       7.0      15    10   10   10    0 
4 Small Laser             RWG       2.0      1      3    0    0    0 
Gauss Rifle Ammo (24)     FSLG      3.0      -      -    -    -    - 
4 Small Laser             LWG       2.0      1      3    0    0    0 
4 Small Laser             AFT       2.0      1      3    0    0    0 

The B (Blitz) configuration is designed to inflict a large amount of damage quickly.  This is most useful in a high speed engagement, where it could potentially be outfitted with 20 RL/10's on hardpoints and 6 air-to-air arrow missiles in an internal bay, potentially inflicting 240 damage multiplied by the high speed engagement speed factor (up to x4).  The small laser blanket primarily assists with point defense but could potentially add further to the damage.  Alternatively, the internal bomb bay could fit 5 antiship missiles. 
Code: [Select]
Workhorse B (Blitz)
Cost: 7,672,500 C-bills
Battle Value: 2,279

Fuel:                         400                   5.0
Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
4 Small Laser           NOS       2.0      1      3    0    0    0 
4 Small Laser           RWG       2.0      1      3    0    0    0 
Cargo (30 tons)         FSLG      30.0     -      -    -    -    - 
4 Small Laser           LWG       2.0      1      3    0    0    0 
4 Small Laser           AFT       2.0      1      3    0    0    0 

The G configuration is for ground support.  It provides twin arrow IV, each with 5 tons of ammunition.   There are two very interesting characteristics of Arrow IV: the direction of the attack is based on the firing unit and multiple friendly units can attempt to TAG with disposition of Arrow IV rounds up to the firing unit.   Hence if the ASF can fly behind an enemy force and one friendly unit can succeed with a TAG, an enemy unit will be hit by multiple shells in the rear arc.  Arrow IV shells also do area effect damage making them quite deadly to infantry.  Note also that TAG can be carried on a hardpoint, providing some nontrivial attack capability vs. ground forces.
Code: [Select]
Workhorse G (Ground)
Cost: 9,209,250 C-bills
Battle Value: 3,157
Fuel:                         240                   3.0
Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
2 Arrow IV              NOS       30.0     10     0    0    0    0 
Arrow IV Ammo (50)      FSLG      10.0     -      -    -    -    - 

The Workhorse A is designed for mixed combat in atmosphere, between enemy ASF and supporting ground forces.   
Code: [Select]
Workhorse A (Air)
Cost: 9,406,875 C-bills
Battle Value: 3,155
Heat Sinks:                   15 [30]                 5
Fuel:                         400                   5.0

Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
PPC Capacitor           NOS       1.0      -      -    -    -    - 
Arrow IV                NOS       15.0     10     0    0    0    0 
2 Small Laser           NOS       1.0      1      3    0    0    0 
ER PPC                  NOS       7.0      15    10   10   10    0 
4 Small Laser           RWG       2.0      1      3    0    0    0 
Arrow IV Ammo (20)      FSLG      4.0      -      -    -    -    - 
4 Small Laser           LWG       2.0      1      3    0    0    0 
2 Small Laser           AFT       1.0      1      3    0    0    0 

The I (Infantry) configuration transports a squad of battle armor while providing Arrow IV support.  It can insert the battle armor by landing and moving as (slow) vehicle or by dropping them with battle armor drop chutes.
Code: [Select]
Workhorse I (Infantry)
Cost: 9,265,875 C-bills
Battle Value: 3,099
Fuel:                         320                   4.0
Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
PPC Capacitor           NOS       1.0      -      -    -    -    - 
2 Small Laser           NOS       1.0      1      3    0    0    0 
Arrow IV                NOS       15.0     10     0    0    0    0 
ER PPC                  NOS       7.0      15    10   10   10    0 
3 Small Laser           RWG       1.5      1      3    0    0    0 
Arrow IV Ammo (20)      FSLG      4.0      -      -    -    -    - 
Cargo (8 tons)          FSLG      8.0      -      -    -    -    - 
3 Small Laser           LWG       1.5      1      3    0    0    0 

The last M (Marines) configuration is designed for inserting battle armor onto the surface of large craft in a combat zone.  It's also useful when fighting Medium ASF units because of the extra fuel.  ASF that move 6/9, 7/11 or 8/12 can use more thrust in a round, but risk structural damage when doing so.  Given that a rabbit/tortoise style pursuit has an inevitable conclusion with the additional fuel of the M configuration.
Code: [Select]
Workhorse M (Marines)
Cost: 8,551,969 C-bills
Battle Value: 2,735
Heat Sinks:                   15 [30]                 5
Fuel:                         520                   6.5
Weapons
and Ammo              Location   Tonnage  Heat   SRV  MRV  LRV  ERV
PPC Capacitor           NOS       1.0      -      -    -    -    - 
3 Small Laser           NOS       1.5      1      3    0    0    0 
ER PPC                  NOS       7.0      15    10   10   10    0 
4 Small Laser           RWG       2.0      1      3    0    0    0 
Cargo (16 tons)         FSLG      16.0     -      -    -    -    - 
4 Small Laser           LWG       2.0      1      3    0    0    0 
4 Small Laser           AFT       2.0      1      3    0    0    0 
Nearly all of these configurations have a natural minor variation where 3 small lasers (wings & aft) are replaced by Guardian ECM or Beagle Active Probe.

There are several design tradeoffs here:
35 tons of HFA armor.  The standard armor levels for heavy fighters is 30-40% lower with an increase in pod space.  However, an increase in pod space buys relatively little extra damage potential.  For example, converting 15 tons of armor into an extra ERPPC and heat sinks yields a 25% increase in long range damage, and an 11% increase in short range damage while decreasing armor by 40% and reducing point defense.   The heavy armor is also helpful vs. critical hit thresholds and in reducing atmospheric control rolls if SO rules are in play.  Having more armor cuts into the ammo payload of the G configuration most critically.

Small Lasers.  Small lasers can be used for point defense, significantly reducing missile attacks, or they can be used at short ranges to inflict damage.  The plausible alternative here is a heavy machine gun.  However, HMGs significantly degrade point defense in the I & B configurations since their additional mass is not offset by reduced heat sinks.  It is technical possible for an inner sphere tech team to fabricate clan HMGs since they are a tech level C item, but the costs (perhaps 150K each) appear prohibitive.  Nevertheless clan HMGs could be useful as an alternative.

Gauss Rifle in F configuration.  It's easy and natural to use an extra ERPPC with a capacitor and heat sinks in the F configuration.  The Gauss Rifle is chosen here for some extra robustness against adversaries with laser reflec armor or in a high speed engagement (Yes, the blitz configuration is better there).  It also enables a fast swap amongst configurations.

Fast swap.  Several configurations (F, A, B, M) can be swapped with tech support relatively quickly since only a few pods need to change between configurations.  This enables rapid reconfiguration into alternate roles.

No XL engine.  Using an XL engine increases available payload by 11% but doubles the cost.  It's generally better to have more ASF, even including the cost of their transport.

Speed.  5/8 is on the slow end for ASF, but it's enough to target most dropships/warships, forcing the enemy to battle or lose their transports.  You can create an even heavier ASF moving 3/5, but the 19% increase in payload isn't worth the loss of ability to target dropships/warships.  6/9 is also a good speed, but you suffer a significant reduction in payload unless an XL engine is used, which is very expensive.  All slower speeds compromise the payload (and many compromise safe thrust) significantly for a general purpose fighter.

Light fighters: the design cannot effectively hunt down light fighters with thrust profile of 9/14 or higher.

Edit: slightly changed armor layout, Tweaks to take advantage of the pod-mounted fuel errata (https://bg.battletech.com/errata/) on page 13.  These are minor---to back them out just standardize on 5 tons of fuel.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 05 November 2021, 04:38:30
My main complaint is that all configs are only useful in assault roles; I know fighters go light/medium/heavy, but this is a clear assault fighter.  A slow moving brick of armor.  So the speed precludes all 'fighter' roles as most enemies can and will turn tail and run from this thing, or line up behind it and stay there forever.

I think a workhorse single design should be fast and in the 50 ton range (meaning alamos can be carried externally--any lighter and you lose this ability); if you are too slow you cant intercept other 50 ton craft loaded with external bombs, which for a 1 design airforce must be a priority.

A heavy design with fighter ability needs to be 7/11 to chase down 6/9 planes at a minimum, but heavy fighters are too slow to intercept, so they are not great workhorse designs despite being brutal superiority fighters.

In the assault shuttle role, I think the flying brick shuttle you have here is tough to beat from the front, but your aft damage/range (where faster enemies will live, and everyone is faster) is lackluster, and you are too slow to beat a fighter.  So this design has merit in some roles, but would need a proper fighter escort fitting it's dedicated bomber nature.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 05 November 2021, 07:23:57
Thanks for this.

My main complaint is that all configs are only useful in assault roles; I know fighters go light/medium/heavy, but this is a clear assault fighter.  A slow moving brick of armor.  So the speed precludes all 'fighter' roles as most enemies can and will turn tail and run from this thing, or line up behind it and stay there forever.

I think a workhorse single design should be fast and in the 50 ton range (meaning alamos can be carried externally--any lighter and you lose this ability); if you are too slow you cant intercept other 50 ton craft loaded with external bombs, which for a 1 design airforce must be a priority.

A heavy design with fighter ability needs to be 7/11 to chase down 6/9 planes at a minimum, but heavy fighters are too slow to intercept, so they are not great workhorse designs despite being brutal superiority fighters.
On defense:
   
On offense:

In the assault shuttle role, I think the flying brick shuttle you have here is tough to beat from the front, but your aft damage/range (where faster enemies will live, and everyone is faster) is lackluster, and you are too slow to beat a fighter.  So this design has merit in some roles, but would need a proper fighter escort fitting it's dedicated bomber nature.
I was imagining avoiding the need for an escort by avoiding ground bombing.  Ground bombing seems inelegant, since Arrow IV rounds are more precise, do quite a bit more damage per ton, and we'll have them anyways for ground support.   In a high speed engagement role, an escort appears unnecessary, because no opposing fighters will have the delta-V necessary to match trajectories.

Makes sense?
Title: Re: The Workhorse Universal Heavy ASF
Post by: idea weenie on 05 November 2021, 14:05:27
I'm seeing this as an assault platform, but it will need escorting by lighter craft (or a similar design) with less proportional armor but more weaponry.  By using a similar massed fighter-type platform it will be a good shell game, as all the fighters will be the same tonnage and thrust but some of them are 1/3 armor and 1/3 weaponry, others are 1/6 armor 1/2 weaponry.  THe best part is that until the first shots are fired the opponent doesn't know which is which.

As a comparison for what it might have to deal with in a similar weight class, the Eisensturm (https://www.sarna.net/wiki/Eisensturm).  The Eisensturm is 95 tons, and for long-range anti-fighter weaponry it carries 2 Gauss Rifles and 2 Large Lasers.  That is a potential of 46 pts of damage  per turn, and it has enough Gauss ammo for 16 turns (736 total potential before the Gauss ammo runs out).  An engine rated for 6/9 T/OT means your Workhorse cannot escape and can only try to spread enemy fire across its armor.  As a comparison, your Workhorse will do 30 pts of damage with speeds of 5/8 for up to 24 turns (720 total potential before the Gauss ammo runs out), against the Eisensturm's 19.5 tons of armor.  Your craft will have an advantage since it has an ERPPC which has infinite ammo, but the Eisensturm can deliver 50% more damage per turn until the Eisensturm runs out of ammo.

My primary concern for this craft is that in space it may run low on fuel (5 tons) before it starts running low on armor (35 tons).  So as the battle goes on you will have several craft waiting by your carrier to be refueled, potentially making them easy targets.

Out of curiosity, since you have access to Gauss Rifles and Double Heat Sinks, why is the engine still a basic Fusion engine?  You could have gotten another 9.5 tons worth of fuel/equipment/armor that way to make this craft nastier.

Very nice brick though
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 05 November 2021, 20:31:34
I'm seeing this as an assault platform, but it will need escorting by lighter craft (or a similar design) with less proportional armor but more weaponry.  By using a similar massed fighter-type platform it will be a good shell game, as all the fighters will be the same tonnage and thrust but some of them are 1/3 armor and 1/3 weaponry, others are 1/6 armor 1/2 weaponry.  THe best part is that until the first shots are fired the opponent doesn't know which is which.

As a comparison for what it might have to deal with in a similar weight class, the Eisensturm (https://www.sarna.net/wiki/Eisensturm).  The Eisensturm is 95 tons, and for long-range anti-fighter weaponry it carries 2 Gauss Rifles and 2 Large Lasers.  That is a potential of 46 pts of damage  per turn, and it has enough Gauss ammo for 16 turns (736 total potential before the Gauss ammo runs out).  An engine rated for 6/9 T/OT means your Workhorse cannot escape and can only try to spread enemy fire across its armor.  As a comparison, your Workhorse will do 30 pts of damage with speeds of 5/8 for up to 24 turns (720 total potential before the Gauss ammo runs out), against the Eisensturm's 19.5 tons of armor.  Your craft will have an advantage since it has an ERPPC which has infinite ammo, but the Eisensturm can deliver 50% more damage per turn until the Eisensturm runs out of ammo.

Comparing with the Eisensturm, it looks like:
SML
Eisensturm564630
Workhorse F 60 30 30
Thus, the Eisensturm has superior firepower in the middle range band, but is comparable at long range and inferior at short range.  Despite being marginally faster than a Workhorse, I'm skeptical that it could stay in the medium range band effectively.  Given the way that vector movement works, keeping in medium range and firing with forward facing weapons is mutually exclusive unless you have at least an extra 4 thrust (yaw, match thrust, yaw).  And if you lose initiative even that won't work.

Is there something scarier than an Eisensturm? Overall, I'm not understanding the case for an escort.
My primary concern for this craft is that in space it may run low on fuel (5 tons) before it starts running low on armor (35 tons).  So as the battle goes on you will have several craft waiting by your carrier to be refueled, potentially making them easy targets.
Fuel is an interesting point here.  It has enough fuel for 36 tons of max thrust, which is a fair but not amazing amount.  Partly the thought is that we can get by with relatively little fuel using omni tech to mount fuel pods when this is anticipated as needed.  Partly, the design is optimized for fleet combat where massive concentrations of fire are in play. 
Out of curiosity, since you have access to Gauss Rifles and Double Heat Sinks, why is the engine still a basic Fusion engine?  You could have gotten another 9.5 tons worth of fuel/equipment/armor that way to make this craft nastier.
I'm looking at this from the logistics viewpoint.  The extra payload tonnage is nice but avoiding XL engines allows you to have extra ASF, dropships, and jump collars to put even more payload into play for the same price.
Very nice brick though
Thanks  :)

Edit: I took a look at existing ASF designs.  It looks like the Kirghiz D (~100 damage/round, 16 tons FA) and Hydaspes (~90 damage/round, 22.5 tons FA) are both fairly potent.  I'd still estimate an edge for the Workhorse F though---brick + 2x critical hitters is potent.   Interestingly, BV goes the other way.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 06 November 2021, 10:57:17
I think the Small Laser batteries need to be 5 minimum.  That takes better advantage of rounding.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 06 November 2021, 12:07:24
I think the Small Laser batteries need to be 5 minimum.  That takes better advantage of rounding.
I hadn't thought about rounding, but I'm not quite following after looking into it.

Capital armor divides by 10 and rounds for all damage by a unit to a location.  Here, the ERPPC+capacitor and the Gauss Rifle are rounding friendly so they do 2 capital damage (or 1 structural) to a capital location they hit.  The SLs are more of a smear, but enough of them are hitting that it's fairly plausible that 2 will hit a location (rounds to 1 capital damage) and reasonably plausible that 5 hit the same location (rounds to 2 capital damage).  If the SLs are hitting in the same location as the big guns, then 4 hits are needed for a good rounding.

Capital fighters (SO page 32) makes fighters faceless with capital scale armor as per above.

In Battleforce, it like you basically add up the damage from all weapons and divide by 10.  Apparently the PPC capacitor is a disadvantage, so we'd probably want to remove that.  After doing so, the damage profile looks like: Short: 5, Medium: 3, Long: 3.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 06 November 2021, 12:13:35
The other reason for 5 Small Lasers is their use in Point Defense.  When using them for that, you either want pairs, or clusters of 5.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 06 November 2021, 12:50:57
The other reason for 5 Small Lasers is their use in Point Defense.  When using them for that, you either want pairs, or clusters of 5.
Huh, I'm feeling confused about this upon rereading the point defense rules.  It says "...reduces the effects of enemy missile attacks ... by an amount equal to half ... the point-defense weapon/bay's capital-scale Attack Value." 

ASF do not have weapon bays, they have individual weapons.  The capital-scale Attack Value of an individual small laser is 0 = round(3/10), so they can't be used for point defense? 

Secondarily, a capital scale Attack Value of 2 halves and rounds to 1 while a capital scale Attack Value of 1 also halves and rounds to 1 so it seems like a bay of 8 small lasers has identical point defense value to a bay with 2 small lasers, as absurd as that may seem.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 06 November 2021, 12:54:07
I'll have to double check StratOps, but I'm pretty sure you bundle the Small Lasers together.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 08 November 2021, 01:20:04
Quote
I don't see how lining up behind is a sustainable tactic?  You have a new initiative each round, implying there is a significant chance that the tail will have to move first.   Also, I'm planning to deploy them in pairs, so a tail will develop a tail.

Few things to unpack.  First, yes you cant line up behind forever, but turns where you lose init your fighter likely cant get on the enemy tail.  Thus their tail is safe due to your slow speed, and your tail is not, again due to your slow speed.  WHEN you have a tail, you have no real defense firing aft.  Thus if you want to keep the brick, think of it like a bomber with their heavy tail guns--a pair of small lasers isnt gonna discourage anything.

Second, you deploy in pairs--but now you are talking formations, unit versus unit balance, ect.  If we stick with BV, you are looking at 6600+ BV for standard pairs of this craft.  That is 6 Corsiar 12Ms, or 2 Eisensturms with 1400+BV in pilot upgrades.  I dont think you can trade at long range versus leveled up Eisensturms, or put down Corsairs fast enough to avoid them overwhelming you.  And since you cant outrun anything, you just lose to any bad matchup, while all your good matchups can run from you. 
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 08 November 2021, 07:34:41
Few things to unpack.  First, yes you cant line up behind forever, but turns where you lose init your fighter likely cant get on the enemy tail. 
It depends on what 'on the tail' means, I guess.   A faster enemy fighter has to be quite close to force aft fire when Workhorse loses initiative.  The exact definition of 'close' varies, with the relative speed, but (for example) if they are one hex away, the could burn 6 thrust to open the range and then 2 thrust to yaw.  The enemy fighter would need to burn 8 thrust to keep the 1 hex range, 2 thrust to yaw, and 2 thrust cancel the excess thrust, so 12 thrust in total (i.e. 4 more).  If the enemy fighter loses initiative, it can yaw 2, thrust 8, yaw 2, which leaves it facing the Workhorse at range 1 after the Workhorse does a thrust 8.  Or, it could Thrust 10 (through the Workhorse's hex to 8 beyond), then yaw 2, leaving the Workhorse able to thrust 7 to reach range 1.  Alternatively, you could add 2 to the thrust and not yaw at the end which would allow you to reach range 3 but with the tail exposed.  Probably the best choice is the first one (yaw 2, thrust 8, yaw 2), which leaves you in the same reference frame as the workhorse if it thrusts 8 to stay close.  So, an 8/12 fighter can avoid tail shots.  Of course the 8/12 fighter will be risking structural damage each round (win or lose initiative), and it will be subject to the small laser attack, implying the incoming attacks average (over wins and losses) as 15 + 3x7.  The '15' in particular will cause critical hits often while the 3x7 chews through the meager armor of a light fighter.   A 9/14 or 10/15 fighter will have even less armor and risk more structural damage, but can open the range a bit further which matters if using individual weapon ranges.
Second, you deploy in pairs--but now you are talking formations, unit versus unit balance, ect.  If we stick with BV, you are looking at 6600+ BV for standard pairs of this craft.  That is 6 Corsiar 12Ms, or 2 Eisensturms with 1400+BV in pilot upgrades.  I dont think you can trade at long range versus leveled up Eisensturms, or put down Corsairs fast enough to avoid them overwhelming you.  And since you cant outrun anything, you just lose to any bad matchup, while all your good matchups can run from you.
The Corsair and Eisensturms are both to slow to avoid rear shots on initiative loss and at least one of them will effectively lose initiative against the second Workhorse so the average damage being inflicted rises. 

(In any case, I'm designing for c-bill cost, not BV.)

Edit: I took a look at this in a bit more depth.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 09 November 2021, 03:46:52
My understanding is that the outnumbering BV modifier was removed in errata due to not calculating properly.  I agree that some modifier for BV should exist, but the TM ones were not very accurate.

While the 'on the tail' you calculated factors rear shots, there is also the shots the enemy takes on your side when you are unable to shoot at all, when the range is not short enough for rear shots so they just maneuver out of arc of your guns.

As a flying brick, you will win initiative some of the time and get to shoot, and will lose initiative some of the time, but with the speed you have you are most effective as a mobile turret--in a scenario the enemy can not leave OR go past you, and must fight you sitting and spinning in the middle of a map.  If this fighter is meant to protect another ship, your speed precludes intercepts as they can fly past/around you, thus you can only perform close air support, meaning the enemy can ignore you and focus on your transport.

Thus, the real role this fighter can provide is slow assault.  When this fighter is the slow assault craft, you force the enemy to engage you as otherwise you hit their soft targets.  This means you need a different fighter for defense, but this flying brick is perfect in assault roles against 4/6 and slower targets that you have enough fuel to reach.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 09 November 2021, 20:35:58
My understanding is that the outnumbering BV modifier was removed in errata due to not calculating properly.  I agree that some modifier for BV should exist, but the TM ones were not very accurate.
Interesting, found it here (https://bg.battletech.com/forums/errata/techmanual-9-january-2014-(v3-02)/msg630310/#msg630310).
While the 'on the tail' you calculated factors rear shots, there is also the shots the enemy takes on your side when you are unable to shoot at all, when the range is not short enough for rear shots so they just maneuver out of arc of your guns.
If the range isn't short enough for rear shots, the superior range over the Corsair 12M should leave Workhorse dominant at longer ranges?  Shots on the side are a possibility.

Overall, I'd give 6x Corsair 12Ms an edge over 2x Workhorse, but it seems close enough that playing it out is required.  I'm not super clear on how important the critical hits, thrust structural damage, and the finer grained discretization of the Corsairs would work out. 
As a flying brick, you will win initiative some of the time and get to shoot, and will lose initiative some of the time, but with the speed you have you are most effective as a mobile turret--in a scenario the enemy can not leave OR go past you, and must fight you sitting and spinning in the middle of a map.  If this fighter is meant to protect another ship, your speed precludes intercepts as they can fly past/around you, thus you can only perform close air support, meaning the enemy can ignore you and focus on your transport.
Given the way that vector movement works, interception of incoming ASF with the goal of keeping them from bypassing to attack transports seems like an iffy strategy?  The enemy just builds up speed and passes by, even if their max thrust is lower.  You'll get to shoot at them in passing, but the enemy ASF can take a round of hits and keep going unless they are seriously outnumbered.

Alternatively, if you are closer to the transport than the incoming enemy ASF and try to build up speed to match velocity with them, you end up presenting your tail to the intercepting ASF which is not a winning strategy. 

Overall, the concept of 'defensive ASF' seems sketchy to me in space due to the bypass strategy.  Maybe it works in atmosphere?  There at least you have a maximum velocity so the 'bypass' strategy doesn't work if the defenders are fast enough.
Thus, the real role this fighter can provide is slow assault.  When this fighter is the slow assault craft, you force the enemy to engage you as otherwise you hit their soft targets.  This means you need a different fighter for defense, but this flying brick is perfect in assault roles against 4/6 and slower targets that you have enough fuel to reach.
This makes sense.

I'm trying to figure out how much an air superiority fighter is worth from a force design perspective. 
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 10 November 2021, 08:18:15
So I used the megamek bot to simulate a bunch, as I am curious on the design philosophy that might arise based on an assault fighter.

I used the 6 small laser sparrowhawk x12, the 12m Corsair x6, the Samurai 25 x6, and the 3/5 Eisensturm x2 against the assault brick pair.

The first note was that when using forced withdrawl, the assault workhorse could cripple an enemy much quicker than it would ever be crippled, so the workhorse won an overwhelming amount versus the corsair.  The 12 sparrowhawks fared better.  Then I took off forced withdrawal to see if there was any change.

Boy, without forced withdrawl, now the corsair and sparrowhawks won convincingly over and over--initiative sinks on fairly crippled craft is my guess, forcing the workhorse brick to waste time killing wounded fighters that previously just flew off the map.  The Samurai went 2v2 in 4 games, but you get 7 samurai versus 6 workhorse so pulling 50/50 with a 16% bv penalty is pretty good.  7v2 went in the Samurai's favor.  The Eisensturm won only 1 game in 5--not enough armor with close enough weapon damage, though in the game they won both Eisenstrums were more or less undamaged, such is the power of lucky streaks.

Takeaway:  Close range damage is the majority of damage, though a few lucky crits at range have a big impact with equal numbers.  Your armor is really good, but the designs focusing on bringing cheap short range fire with more speed give you fits unless you can scare them away with forced withdrawal.  I learned a lot about what makes a good brawler though--I expected the samurai despite being cheaper to spank but it did worse than the 12m corsair in the 50t 6v2 category.  Sparrowhawks remain really good.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 10 November 2021, 15:14:08
Takeaway:  Close range damage is the majority of damage, though a few lucky crits at range have a big impact with equal numbers.  Your armor is really good, but the designs focusing on bringing cheap short range fire with more speed give you fits unless you can scare them away with forced withdrawal.  I learned a lot about what makes a good brawler though--I expected the samurai despite being cheaper to spank but it did worse than the 12m corsair in the 50t 6v2 category.  Sparrowhawks remain really good.
This is very helpful, thanks.  I haven't played with megamek simulator---maybe I should.

Do you happen to know how the Workhorses died in these combats?

If I understand correctly, 'forced withdrawal' means the ASF suffered critical hit to engine or fuel, all weapons were destroyed, half of structure is lost, or 4+ pilot hits.  Do you know which it was typically?

Cost-wise, we have 12x Sparrowhawk = 21M, 2x Workhorse = 18M, 6x Corsair = 13M
BV-wise, it's 12x Sparrowhawk = 7644, 2x Workhorse = 6648, 6x Corsair = 6726
Transport-wise it's 12x Sparrowhawk = 12 ASF bays, 2x Workhorse = 2 ASF bays, 6x Corsair = 6 ASF bays

The transport advantage of the Workhorse stands out quite a bit.  The cost advantage of the Corsair is less significant since you could convert the Workhorse to not be OMNI and look at similar prices.   In essence, the price of OMNI (and the price/tonnage of the OMNI pods) is the price of being able to reuse the Workhorse for many other roles. 

I'm still wondering about the air superiority question though.  There are two questions:
1) If we are in atmosphere and we need to attack some other unit, how well can some enemy ASF force us to deal with them instead?
2) If we are in atmosphere and need to defend some unit from enemy ASF, how well can that be done compared to some other unit? 

This is different from space, because in atmosphere you have a top speed.  At high altitude, it looks like every unit has the same top speed.  On the low altitude map, it matters more since velocity is halved each round by default.  As an enemy ASF it seems like the best strategy is to come in from high altitude (where you can bypass any defenders) and descend to attack some ground target.  To defend against this, you want any defensive ASF to be "above" the target and drop on any enemy ASF that are incoming, since they are either coming in at high altitude (encountering you) or coming in slow at low altitude (providing time to pounce). 

Overall, I'm not yet seeing enough of an advantage for a smaller/faster unit.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 10 November 2021, 18:38:28
The Corsairs seem to have a decisive advantage as planetary defenders.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 10 November 2021, 21:52:12
The Corsairs seem to have a decisive advantage as planetary defenders.
How so?
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 11 November 2021, 00:19:27
Quote
The Corsairs seem to have a decisive advantage as planetary defenders.
How so?

Presumably because in space around a planet, you wont want to land your transports in the atmosphere while corsairs are flying about, and corsairs dont need a transport bay, thus the very real issue of needing 6 ASF bays to counter your 2 workhorse bays is negated thanks to taking off from the planet.  This goes double for the sparrowhawks who get even more benefit for not needing 12 bays to lug around a force needed to counter 2 assault fighters.

For withdrawals, I didnt save the logs but SI damage and engine hits were the ones I remember standing out the most; fuel hits that dont explode I think also count as crippling damage per rules, they just are not as noticeable so im not sure how the bot handled those.  All weapons destroyed never came up due to small lasers everywhere unless it was some otherwise mangled fighter with 1-2 points of SI left, and most pilot damage happened on ejects and never anywhere else.  In particular, a threshold to an engine causing a fighter to withdrawal makes a bigger impact than a half dead fighter with 3 SI left, so I imagine the pretty common engine hit forced withdrawal hurts the most, versus fighting with a near full armor 4/6 corsair with 17 heat sinks instead of 19 when forced withdrawal is off.

In atmosphere, one note about extra thrust I have found from actual games (not bots) is that if you can out climb your opponent, then when you lose initiative you can escape into their deadzone much easier than trying to outfly them by going up, as their max velocity on a given level is capped, and your max down elevation is capped by a PSR.  A way around this is to fight at the max elevation, but that tactic is akin to putting your rear against a board edge the whole game--gamey since one map arbitrarily ends at 10 and the other doesn't use the same scale.  This ability to outclimb your opponent and only attacking when the enemy is not above you is pretty real world accurate--the same tactic saved a lot of lives when american fighters learned not to engage zeros with the height advantage, and only fight them when starting from a higher level than them.

Another thing about thrust on the low speed map is for extra turning.  A 7/11 fighter can make 4 more turns than a 5/8 fighter even if both have the same velocity.  While it is less powerful than outclimbing your opponent on a lost initiative, there are deadzones a 5/8 fighter cant turn into at high velocity that a faster fighter, if they know where they are, can place themselves in.  Megamek is handy for being able to show possible moves; unlike xwing where you can look at your opponents dial to see what possible turns they can make, in battletech there are hundreds of permutations so trying to figure out turning deadzones is pretty tough at a glance.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 11 November 2021, 07:20:58
Exactly, thanks!  :thumbsup:
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 11 November 2021, 08:01:33
Presumably because in space around a planet, you wont want to land your transports in the atmosphere while corsairs are flying about, and corsairs dont need a transport bay, thus the very real issue of needing 6 ASF bays to counter your 2 workhorse bays is negated thanks to taking off from the planet.  This goes double for the sparrowhawks who get even more benefit for not needing 12 bays to lug around a force needed to counter 2 assault fighters.
Would you be significantly more able to land transports if the Workhorses were flying around instead?  I can see how that would matter if the number of transports outnumbered the ASF, but that seems like an extreme scenario.

W.r.t. Forced Withdrawal/Destruction, I'm wondering about armor spread.  In particular, taking some armor from wings to place aft seems like it could potentially be useful to increase survivability without significantly decreasing survivability in combat against dropships/warships.

I wish we could define our own forced withdrawal criteria.  Something like 4+ cockpit hits, fuel explodes, 3 or less structure remaining, zero armor remaining on a facing, and no weapons left seems reasonable.

How can a 7/11 fighter with the same velocity as a 5/8 fighter take 4 more turns in a round?  I'm not following that part.  You must have a minimum velocity of 4 to make 4 facing changes, and you need velocity/2=2 thrust to make a powered turn, so it looks like you only gain one additional facing change?
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 12 November 2021, 07:52:03
Ah I play with aero on btech maps in megamek, so its 16 MP per thrust and 1 MP per turn.  That may not match up to regular rules.

Point is still that faster craft can outturn slower craft.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 13 November 2021, 11:24:11
Ah I play with aero on btech maps in megamek, so its 16 MP per thrust and 1 MP per turn.  That may not match up to regular rules.

Point is still that faster craft can outturn slower craft.
I've been fooling around with megamek simulation (thanks for pointing it out).  The Princess bot seems ok at doing immediate attack things, but doesn't seem to reason across multiple steps at all.  For example, when I turn on vector movement, it's basically impossible to keep the fight on the map.   I also noted that the PPC capacitor is always unused leaving the Workhorse design oversinked. One thing that I hadn't appreciated is the degree to which vector movement starts making longer range weapons more interesting.

After fooling around for awhile, I saw Workhorse being killed by armor removal from Nose x2, Aft x4, Wing x4, Aft+Wing x4.  Given this, I think it's reasonably well balanced between aft & wing armor for dogfight vs ASF situations.  I think the AI doesn't know how to roll sides effectively, since almost every Wing kill was a left wing.  Given that I shifted only a small amount of armor from wings to aft, enough to avoid an aft critical hit from a gauss.

You also convinced me to look into custom dogfighters for planetary defense.  After fooling around a bit, I came up with the Devilbane (https://bg.battletech.com/forums/aerospace/devilbane-dogfighter/) which seems to check the boxes in terms of providing enough additional force for the cost (x2+) to be worth having a second design from a force design perspective.  It's about 15% more expensive than the Corsair, but faster, more heavily armored, and with more short range weapons.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 14 November 2021, 04:29:33
I dont like vector rules optional movement, as the base rules with turns costing more the more velocity you have, when crunching math, DOES the vector calculation for you, so its not like vector movement is more math accurate.  I know with vector rules slower fighters get more power as they can still turn all day (at velocity 20 you can do a 360 in your 5/8 fighter and still accelerate 2 hexes any direction you want) BUT vector rules lead to gameplay at higher velocities since it is so easy to spin in place.  Thus flying off the map happens more with vector movement since you build a bunch of speed, strafe the enemy for side hit bonuses, and run off the table before you can slow down.  With normal space movement you tend not to build too much speed as you still need to turn, thus fights tend to use less space and 'flow' better from a gameplay view for me--also, you only get side bonuses when your fighter cant shoot back, so its more balanced than drifting in space using 0 acceleration in vector mode and still getting a side bonus vector while facing the enemy.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 14 November 2021, 07:33:50
I think the argument for vector movement is realism---it should be possible in space.  From the game play perspective, it makes multiround reasoning more valuable---a bit more chess, and a bit less whack-a-mole.  Perspectives may vary about whether that is good or bad.

...also, you only get side bonuses when your fighter cant shoot back, so its more balanced than drifting in space using 0 acceleration in vector mode and still getting a side bonus vector while facing the enemy.
I believe you use your actual facing rather than your vector to determine hit bonuses? 

Baseline space movement is egregiously unrealistic in one way: the ability to reduce velocity without changing facing.  That's just plain inconsistent with every depiction.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 14 November 2021, 10:24:09
Quote
Baseline space movement is egregiously unrealistic in one way: the ability to reduce velocity without changing facing.  That's just plain inconsistent with every depiction.
For me its that you move 2x the number of hexes that you should the turn you accelerate/decelerate.  Also, turns in vector mode for dropships and fighters are basically free, as a thrust point is 9k meters of movement in 1 minute (using the correct thrust to move value), 4.5k meters if you also stop spinning when you get your desired heading.  So unless your fighter is 1000 meters long, 1 thrust will spin you like a top.  So yeah, vector movement is not realistic though it pretends it is more realistic, thus I like the normal rules as they have less record keeping.

I thought your heading determined your targeting facing; im glad to see that isnt the case at least.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 14 November 2021, 11:12:15
For me its that you move 2x the number of hexes that you should the turn you accelerate/decelerate. 
I agree it's not perfectly realistic here.  There's also a low order issue in that 1g of acceleration only gives you velocity sufficient for 35.3 km/minute rather than 36 km/minute.  Normal movement has these same issues.  There's a saying: perfect should not be the enemy of good, so I'm inclined to tolerate these other fails, which apply to the standard rules as well.

Nevertheless, there are some 'easy' fixes here.  You could for example let a turn's delta-v result in just half movement and reduce scale to precisely 35.3/2 km/hex.  Delta-V in a turn is declared that turn (and hence is easy to track), and the scale of hexes is pretty nominal anyways.
Also, turns in vector mode for dropships and fighters are basically free, as a thrust point is 9k meters of movement in 1 minute (using the correct thrust to move value), 4.5k meters if you also stop spinning when you get your desired heading.  So unless your fighter is 1000 meters long, 1 thrust will spin you like a top.  So yeah, vector movement is not realistic though it pretends it is more realistic, thus I like the normal rules as they have less record keeping.
The question here is: Can you vector the primary thrust of fighters?  All the art suggests 'no'.  Hence, I always thought of the 1 point per hex side as use of (radically weaker) attitude thrusters.  If you think it's vectored primary thrust, then spinning should indeed be free and you could even have an excuse for negating thrust.  Thus, another set of 'realistic' rules would be the baseline space movement, except that:
Title: Re: The Workhorse Universal Heavy ASF
Post by: Cannonshop on 14 November 2021, 22:29:40
I agree it's not perfectly realistic here.  There's also a low order issue in that 1g of acceleration only gives you velocity sufficient for 35.3 km/minute rather than 36 km/minute.  Normal movement has these same issues.  There's a saying: perfect should not be the enemy of good, so I'm inclined to tolerate these other fails, which apply to the standard rules as well.

Nevertheless, there are some 'easy' fixes here.  You could for example let a turn's delta-v result in just half movement and reduce scale to precisely 35.3/2 km/hex.  Delta-V in a turn is declared that turn (and hence is easy to track), and the scale of hexes is pretty nominal anyways.The question here is: Can you vector the primary thrust of fighters?  All the art suggests 'no'.  Hence, I always thought of the 1 point per hex side as use of (radically weaker) attitude thrusters.  If you think it's vectored primary thrust, then spinning should indeed be free and you could even have an excuse for negating thrust.  Thus, another set of 'realistic' rules would be the baseline space movement, except that:
  • You can face an ASF however you want for the purpose of firing and taking damage.
  • Half of delta-v is applied in the round of acceleration.
  • The scale of space hexes is 35.3/2 km.

I don't know, I think that kind of movement should be reserved for dedicated space fighters.  The ASF units kind of strike me as using nose-attitude thrusters and either flexible outlets like the F-35 or paddles like the SNAKE  (https://en.wikipedia.org/wiki/Rockwell-MBB_X-31)prototype, basically airframes adapted to fly briefly in space, which is wholly consistent with the 'ground focused' nature of militaries in the Battletech setting-Aviation being primarily about ground support and operation at close ranges to the surface, usually in atmosphere, but a few rare occasions taken further out, because ground focused commanders will want aviators to fly airplanes in their support, and won't consider exoatmospheric operations to be that significant, so they won't allocate budgets to developing it, instead favoring whatever will let their 'air support pilots' have an easier time flying it like an aeroplane, rather than a rocket-driven helicopter or whatever you might say the Starfury from Babylon 5 flies like.

for that sort of movement, you would want your aviator sitting as close to center of gravity as possible to reduce disorientation, with engine outlets pushed out away from center of gravity to increase leverage on turns and spins in vacuum.  B'Tech's ASF designs tend to put the cockpit near the nose-where you'd want it when you're divebombing and dropping bombs, but not where you'd want it if you're doing pirouettes to swing the nose ninety degrees off your column of thrust.

Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 14 November 2021, 23:08:28
This is very true that aerofighters are mostly designed with atmosphere combat first and space as a tacked of feature of massive fusion engines.  We do know that all aerofighters have a minimum of vstol vectoring for main thrust, but there probably should be a quirk for maybe no vstol but space vectoring engines.  Thus you can't hover but can spin for free.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Cannonshop on 15 November 2021, 09:20:17
This is very true that aerofighters are mostly designed with atmosphere combat first and space as a tacked of feature of massive fusion engines.  We do know that all aerofighters have a minimum of vstol vectoring for main thrust, but there probably should be a quirk for maybe no vstol but space vectoring engines.  Thus you can't hover but can spin for free.

I'd actually say that should be an option that costs something in the construction instead, or require dedicated airframe (spaceframe?) designs, maybe some kind of hybrid Smallcraft/Fighter type gunship barred from re-entry, at least, at the start.  Atmospheric flight, and maneuverability in space are kind of mutually exclusive concepts.  shapes that do well at high mach in atmosphere tend to be centralized, thin, and long, while shapes that do well in vacuum will tend to be...not centralized, thin, or long along the main axis of thrust.  Something spherical with four engines out on booms (*or polygonal with four engines out on booms) will get more 'swing' for the thrust (Fuel) than something needle-shaped with the vectored thrust close to centerline.

(One of these looks like a Battletech Aerospace fighter, the other doesn't.)

Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 15 November 2021, 10:11:07
Something spherical with four engines out on booms
The Mammoth is the only standard design I'm aware of with this flavor.  The ability to asymmetrically power opposite drives should enable a fast spin.   If you could additionally reverse the engine units (Firefly style) it would enable you to decelerate. 
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 16 November 2021, 00:41:26
In thinking, quirks could probably handle this.  There are already quirks for being bad in atmosphere, so an expensive space vector quirk would work well (it needs to be double cost of the negative probably)
Title: Re: The Workhorse Universal Heavy ASF
Post by: Cannonshop on 16 November 2021, 09:22:23
The Mammoth is the only standard design I'm aware of with this flavor.  The ability to asymmetrically power opposite drives should enable a fast spin.   If you could additionally reverse the engine units (Firefly style) it would enable you to decelerate.

the mammoth's engines are STILL close to the center of mass/center of gravity, which is like a centerline mount in that it's going to give you a smoother ride during boost phase, but it's not exactly 'maneuverable'-the placement is more about being able to put down in a socket without expensive, massive, leg-jacks and still have the engines clear to thrust on takeoff.

For what I'm talking about, it's more like "Let's build something with a hell of a lot of thrust, that can flip and spin and side-walk, but it doesn't need landing gear or atmospheric flaps and it doesn't need to be streamlined."

Which is why  i'm saying you can't do it with 'quirks' and get what you're looking for-the layout just doesn't work, you'd probably need an entirely different record sheet and crit table to get that 'B5 starfury effect' in your movement profile-where you can thrust backwards or sideways at the same rates you're going forward.

The Battletech(tm) universe isn't the kind of setting where such a beast could evolve naturally-everything, and I mean everything, in Battletech is focused on the ground game, with ASF and Naval assets being dual-focused at best.  It's a "Warriors who sometimes fight in space" type universe, not a "Spacers who sometimes go to war" type universe.  When someone kindly tries to tack on elements of the latter, it ends up being klunky and kludged because of that.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 16 November 2021, 19:38:53
the mammoth's engines are STILL close to the center of mass/center of gravity, which is like a centerline mount in that it's going to give you a smoother ride during boost phase, but it's not exactly 'maneuverable'-the placement is more about being able to put down in a socket without expensive, massive, leg-jacks and still have the engines clear to thrust on takeoff.
The Mammoth engines are apparently about 130 meters from the center of mass.  The angular momentum of a uniform sphere is 2/5 M*r^2 = 352e6 tons*m^2.  For an acceleration potential of .5g in an engine, the force is F=ma=52K tons * 4.9 m/s^2=254800 tons*m/s^2 and the torque is Fr =33e6 tons*m^2/s^2.  These imply the rotational acceleration is .09375 radians/s^2.  To do a 180, you want to accelerate with one engine on halfway and then one engine on the other way.  This implies each thrust needs to traverse pi/2 radians.  Using sqrt(2 * pi/2) = ~6 seconds + the same to decelerate suggests the Mammoth could reverse orientation in 12 seconds with zero angular momentum.


Title: Re: The Workhorse Universal Heavy ASF
Post by: idea weenie on 16 November 2021, 21:18:07
The Mammoth engines are apparently about 130 meters from the center of mass.  The angular momentum of a uniform sphere is 2/5 M*r^2 = 352e6 tons*m^2.  For an acceleration potential of .5g in an engine, the force is F=ma=52K tons * 4.9 m/s^2=254800 tons*m/s^2 and the torque is Fr =33e6 tons*m^2/s^2.  These imply the rotational acceleration is .09375 radians/s^2.  To do a 180, you want to accelerate with one engine on halfway and then one engine on the other way.  This implies each thrust needs to traverse pi/2 radians.  Using sqrt(2 * pi/2) = ~6 seconds + the same to decelerate suggests the Mammoth could reverse orientation in 12 seconds with zero angular momentum.

Doesn't this require that the engine is pointing at right angles to the hull?  Instead most Dropships have the engines mainly point 'down', so you would get rotational thrust by turning off the engines on one side but not as fast as you calculated.  Now I'm looking at the angle created between the center of that engine bell and the center of the ship's mass, and a line going directly down from the center of mass, and wondering if you would use the sin or cosine of that angle to make the calculations (likely cosine).

Basically a ship with its engines at its equator would be able to have excellent maneuverability since all the engines are at right angles to the hull, but a ship with all its engines in a cluster at the base would not have as much maneuverability since most of their thrust would still be going towards the Dropship's center of the mass
Title: Re: The Workhorse Universal Heavy ASF
Post by: Cannonshop on 16 November 2021, 23:22:50
Doesn't this require that the engine is pointing at right angles to the hull?  Instead most Dropships have the engines mainly point 'down', so you would get rotational thrust by turning off the engines on one side but not as fast as you calculated.  Now I'm looking at the angle created between the center of that engine bell and the center of the ship's mass, and a line going directly down from the center of mass, and wondering if you would use the sin or cosine of that angle to make the calculations (likely cosine).

Basically a ship with its engines at its equator would be able to have excellent maneuverability since all the engines are at right angles to the hull, but a ship with all its engines in a cluster at the base would not have as much maneuverability since most of their thrust would still be going towards the Dropship's center of the mass

I'm kinda thinking he's presuming the engines can be rotated or spun, or have outlets on each end to get that kind of spin, seeing as there's no drag in space to help with the turnover.

Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 17 November 2021, 00:41:55
If the engines are all pointing down, you fire the other engine to slow down the first.  Hence why turns take 12 seconds if his math is correct.  They would take 6 seconds if the second engine could spin and provide 2x the thrust.  Now, with 4 engines and a 3/5 speed, 1 thrust from 1/4th your engines is hitting overthrust, so overthrusting an engine to spin a mammoth 180 in 12 seconds is NOT recommended.

Spinning a 180 in 12 seconds, the peak centrifugal force for people at the edge of the hull would be almost 4gs (the SI of 20 can handle 10g so the ship will be fine).  So people on the bottom of the ship would be smooshed and people at the top of the nose would fly into the ceiling.  If the crew are all on the deck 36 meters or less from the center of the hull, its a 'comfortable' 1 g.  Better alert your crew to get midship before a 12 second 180!
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 17 November 2021, 02:09:30
Doesn't this require that the engine is pointing at right angles to the hull? 
The mammoth has 4 equidistant engine units spaced around the equator and pointing aft.  To generate the spin, you have one fire and the opposite one not for 6 seconds, then shut off the original one for 6 seconds while you let the opposite one fire. 

For @Cannonshop: this should work with the fixed engine units depicted in the art as long as you have fine control over their on/off state.
If the engines are all pointing down, you fire the other engine to slow down the first.  Hence why turns take 12 seconds if his math is correct.  They would take 6 seconds if the second engine could spin and provide 2x the thrust.  Now, with 4 engines and a 3/5 speed, 1 thrust from 1/4th your engines is hitting overthrust, so overthrusting an engine to spin a mammoth 180 in 12 seconds is NOT recommended.
If .75 thrust is used instead, the time becomes ~14 seconds.
Spinning a 180 in 12 seconds, the peak centrifugal force for people at the edge of the hull would be almost 4gs (the SI of 20 can handle 10g so the ship will be fine).  So people on the bottom of the ship would be smooshed and people at the top of the nose would fly into the ceiling.  If the crew are all on the deck 36 meters or less from the center of the hull, its a 'comfortable' 1 g.  Better alert your crew to get midship before a 12 second 180!
Let's go with .75 thrust, since it's a fair point that we should be cautious about max thrust.  It takes 7 seconds to reach to reach peak rotational velocity.  If we go with 130m radius, that means the rotational longitude experiences a peak velocity of v = 2 * pi/2 * 130m / 7s = 58 m/s (=2x average velocity).   This creates a centrepital force of 58 m/s *58 m/s /130 m = 25.9 m/s^2 which is 2.6g.  That's definitely in the broken-bones-if-you-aren't-prepared regime. 

The equations are much friendlier at smallcraft scales (a factor of 6 less centrepital accel), but I'm not aware of any Mammoth-style smallcraft.
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 17 November 2021, 02:37:25
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That's definitely in the broken-bones-if-you-aren't-prepared regime

Yep, BUT that is spinning a 180 in 14 seconds, across a 1 minute turn, meaning if you didnt slow down immediately you could spin the ship 1080 degrees with just 3 thrust from 1/4th your engines.  If the crew are centrally located (red alert) you could spin like a top in 1 minute for no ill effects, corkscrewing all the while over.  Ships in btech are fast! after all.

Also means round dropships dont need grav decks after all--they are grav decks.  So you can drift all you want, spinning end over, so the bottom half of your ship has 'normal' gravity (though you need to walk on the ceiling on the top half of your ship)
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 17 November 2021, 21:19:50
Also means round dropships dont need grav decks after all--they are grav decks.  So you can drift all you want, spinning end over, so the bottom half of your ship has 'normal' gravity (though you need to walk on the ceiling on the top half of your ship)
This is something I hadn't appreciated.  It makes coasting a much more viable activity.  In practice, I expect you would want to spin the ship on its central axis, which should be doable (more slowly) using attitude thrusters.  Ever room would have two floors: the thrust-floor (when the main engine is on) and the out-floor (when the ship is spinning without thrust).
Title: Re: The Workhorse Universal Heavy ASF
Post by: DevianID on 17 November 2021, 23:51:41
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Ever room would have two floors: the thrust-floor (when the main engine is on) and the out-floor (when the ship is spinning without thrust).
And probably a net in the bigger rooms for 'oops' crates/items left unsecured.
Im reminded of the expanse when the tool box was left open before heavy combat maneuvering.  Yeah, definitely arresting nets in the tech bay.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 19 January 2022, 07:11:34
I was trying to figure out external stores for fuel related to some configurations and seem to be missing some critical rule.   Maybe someone knows where the right rules are?

TM page 196 says "external stores hardpoints, which may be used to carry... additional fuel tanks...".  However, TM page 346 does not list fuel as an option.  Additionally, the "Extended Fuel Tanks" entry on page 244 does not cover aerospace fighters, even in the errata.

The TM errata (https://bg.battletech.com/wp-content/uploads/2021/09/TechManual-2021-09-21-v5.0.pdf) page 25 says: "The internal fuel capacity of an OmniFighter's base configuration must be fixed...Additional fuel may be pod-mounted, however."  In this context, pod-mounted seems to refer to an omnipod, which implies you can mount an extra ton of fuel internally on a ton-for-ton basis.  That's interesting---it suggests that good omnifighter designs should have relatively little fixed fuel?
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 19 January 2022, 18:33:58
I wouldn't sweat page 346 much... the heading there is "External Stores Hardpoint Weapons", and fuel isn't a weapon.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 19 January 2022, 19:51:22
I wouldn't sweat page 346 much... the heading there is "External Stores Hardpoint Weapons", and fuel isn't a weapon.
I found the rule: it's SO page 35 under 'external fuel tanks'. 

The TM errata remains pretty interesting from a design perspective, as there are some missions which require much less fuel than others.  An example of a very low fuel mission is a ballistic high speed pass (either defensive or offensive).  Being able to customize fuel via omnipods is something I'd like to explore.
Title: Re: The Workhorse Universal Heavy ASF
Post by: Daryk on 19 January 2022, 20:39:03
Glad you found it!   :thumbsup:
Title: Re: The Workhorse Universal Heavy ASF
Post by: Lagrange on 23 January 2022, 20:45:02
I added some tweaks around fuel usage.  It looks like 3 tons as a baseline and then omnipod mounting to reach either 5 or 6.5 tons is a good approach.  Aside from that,

Title: Re: The Workhorse Universal Heavy ASF
Post by: Phobos on 19 February 2022, 18:35:04
5/8 as universalist ASF? No way. 5/8 is the 3/5 of space combat and is used to "assault" Dropships and Warships, not to dogfight etc.