I've got a couple of picky Physics enthusiasts/majors/Engies..how hard is Aero?

[Nerhesi]

I guess this would be posed to the Crays and such people - but, could you give me a rundown of the magic in BT? Knowing full well that any sufficiently advanced tech is magic anyways, but imagine yourselves approaching this game with a very skeptical attitude; what are the "what the huh?!" areas for you.

[cray]

In the aerospace game, if you use advanced movement?

To me, not in any order:

1) Fusion rocket efficiency. They use fuel and fighters can run out pretty quick, but they're more efficient than fusion should be able to manage.

2) KF drives. The hyperspace weirdness is marvelously internally consistent and well-outlined, but it isn't real physics. I actually like the system quite a bit, but it is different.

3) Short detection ranges. BT sensors are blind as bats in space. The x-rays of a drive plume should be visible across a star system, and even optical and thermal systems should have much longer ranges against most BT spacecraft. On the other hand, the sensors work for the game, which has short gun ranges. You have plenty of time to spot and respond to most threats, and you can hide your ship for sneaky approaches.

4) Ballistic weapon ranges are too high. They require very high muzzle velocities, equal to tens of kilometers per second. This can be excused for capital weaponry, but giving conventional ACs and missiles those velocities are a stretch. On the other hand, if you're only looking at hexes and not kilometers (the game doesn't care about kilometers), it doesn't matter.

5) Balloons. While BT's fighters are too small for the liquid hydrogen they carry, BT's large spacecraft - DropShips, JumpShips, and WarShips - are giant, thin-skinned balloons. Their mass would be more reasonable if their stated dimensions were divided by a factor of 2 or 3. Again, the dimensions have almost zero impact on the game, it's just a fluff oddity.

Otherwise, the aerospace setting is pretty good about its realism. If you use the advanced movement rules, you should have no complaints about the 2D movement system. It is fairly Newtonian, if missing a third dimension, and the hex sizes are based on specific acceleration / delta-V values. (300m/s for 1 minute = 1 hex).

There are no magical force fields, no gravity control, no structural reinforcement fields, just fairly realistic engineering. If they have any questions or concerns, feel free to share here and I'll try to answer.

[idea weenie]

One nit they might have is acceleration through a hex would only get you half the distance traveled, rather than the full amount.  I.e. assume a vessel has zero momentum to start with.  You accelerate to a speed of 2, so your final velocity is 2.  However, your average velocity is 1, so you move the vessel 1 hex, but mark down the final velocity as 2. Next turn, if you don't accelerate, you move 2 hexes.

Of course, this ignores the idea of a 6/9 vessel accelerating at a thrust of 6 for half the time, so it technically uses 3 pts of fuel f.  However, since all of its acceleration is at the start of the turn, it would move more than 3 hexes.  Since it did not start out at a speed of 6 though, it would move less than 6 hexes.

Ask them if they want to get into that sort of math, or just go with acceleration + prior velocity = hexes traveled.

[rlbell]

One nit they might have is acceleration through a hex would only get you half the distance traveled, rather than the full amount.  I.e. assume a vessel has zero momentum to start with.  You accelerate to a speed of 2, so your final velocity is 2.  However, your average velocity is 1, so you move the vessel 1 hex, but mark down the final velocity as 2. Next turn, if you don't accelerate, you move 2 hexes.

Of course, this ignores the idea of a 6/9 vessel accelerating at a thrust of 6 for half the time, so it technically uses 3 pts of fuel f.  However, since all of its acceleration is at the start of the turn, it would move more than 3 hexes.  Since it did not start out at a speed of 6 though, it would move less than 6 hexes.

Ask them if they want to get into that sort of math, or just go with acceleration + prior velocity = hexes traveled.

If the turn length was short, seconds instead of a full minute, the engines could be an infinite impulse drive.  The drive delivers an approximation of an infinite impulse over an approximation of a zero duration, producing a finite, but instantaneous, amount of delta-v.  At low time scales, an Orion drive is a reasonable approximation of an infinite impulse drive.

Doing the math to accurately model acceleration, fuel use, and displacement is not actually that hard, but you have to break the turn up into segments.  A game that takes it all into full account is Attack Vector: Tactical, by Ad Astra Games.  The game's tag line is "We do all the scary math so you can blow stuff up.", and the game aids meet that claim. 

To get your physics enthusiasts/majors/Engies into Aero, first download and print the tutorial rules from Ad Astra Games' website and go straight to ship combat with lasers-- without laying down any chocolates (you would need to read the tutorial).  After they flounder in three dimensions, and start to get frustrated, offer to show them a game that is much less simulation and much more game.

[VhenRa]

Don't they use a variant of those rules for a Honor Harrington Game?

[idea weenie]

Don't they use a variant of those rules for a Honor Harrington Game?

Yup, Sagamani Island Tactical Simulator. Compared to Battlespace, the turns are 7.5 times as long, and the hexes are ~7000 times longer.

[SCC]

SITS shows us a reason why weapons are so short ranged, things sort of came apart when they are longer ranged

[rlbell]

Yup, Sagamani Island Tactical Simulator. Compared to Battlespace, the turns are 7.5 times as long, and the hexes are ~7000 times longer.

SITS (I have version 1) is among the games that I doubt that I will ever get to play (need friends with less math phobia[I miss university]).  The one scenario that i would love to play is the convoy raid with the players being allowed to choose their forces from the table, instead of rolling for them, and I would offer to play the Republic of Haven.  Of course, I would take an Astra class Q-ship, but would not place it on the map, just so I could see the face of my opponent when his battlecruiser presents the unsuspected (if I am lucky) Q-ship with an up-the-kilt shot of missiles and grasers.  He would ask how I could hide a 4 megaton ship in empty space, and I would reply that its not hidden in empty space, but in a convoy of freighters.

[idea weenie]

The fun part with the Astra is it can fire missiles for a very long time.  An Astra Q-ship carries 120 missiles per tube, while most Manty, Silesian, and Havenite cruisers carry only 20 missiles per tube.  So an Astra can volley missiles until the enemy cruiser has emptied the magazines for that side, rolled to present the other side, fired all the missiles from that side, and the Astra still has 2/3 of its missiles for that side available.

The books for the Dreadnoughts and Superdreadnoughts haven't come out yet, so the Astra is currently the ship with the largest magazines that has a game sheet for it.


For those who wonder why I measure missile capacity exclusively, it is because missiles have a range of ~30-40 hexes, and beam weapons have a range of ~3-4 hexes.

[VhenRa]

And those are still the early books single-drive, capacitor driven missiles.... imagine the sort of range a modern Mark 23 with three drives and a fusion bottle powering it would have?

[idea weenie]

And those are still the early books single-drive, capacitor driven missiles.... imagine the sort of range a modern Mark 23 with three drives and a fusion bottle powering it would have?

Not to mention Apollo guidance platforms mixed in with each wave for better accuracy.  Technically you should only need 1 Apollo, plus maybe a backup or two to handle each wave.

[Medron Pryde]

For ballistic weapons having the ranges they do, the only thing that makes sense to me is to say that they have some kind of final maneuvering thruster package that sends them on their terminal attack vector after the ship fires them "generally off thataway" and all that.

;)

The idea that an autocannon chattering away and its shells flying across space to hit an enemy that is frantically maneuvering to keep from getting hit is going to be anywhere near as accurate at anywhere near as long a range as a laser or a truly guided missile sorta makes me laugh.  ;)

Still, I do love throwing broadsides of NAC 20s at the Bad Guys.  The Bad Guys being the guys fighting the Good Guys.  And I'm the Good Guys.

;)

[pensiveswetness]

OK while the official question eventually gets a glance, ill ask here...

(all movement is low altitude maps, the each hex is a standard BT map method)

OK, assuming I'm looking at a aerotech sheet printed from HMaero, with the movement chart under the sheet stats, how will a Mechbuster (moving at 4/6 max because of bomb load)'s movement look in print, if the fighter is starts the game at Velocity 2... how much MP per turn do i spend

1) to maintain that velocity thru out the secession?

2) how much MPs do i have left per turn for allowance for maneuvers, if i wish to have as much loiter/harassment time for ground support attacks?

I'm really trying make sure I'm doing the rules correctly here and I'm still, just enough not certain I'm comprehending correctly, as far as aero is concerned

(and that's a lot of I'ms)

I picked the Strategic Ops pdf only recently for the Repair Rules (TU for who ever told me to get it!) so I've only glanced at the aerospace side, totally unready to use those rules (yet)...

OK here's another beer can stew:

how would i run a session with aerospace where the ground attack occurs on a chunk of ice that Battlemechs are defending (think the space ice mission from Activision's Mechwarrior 2: Mercenaries) what do i need to consider for a fair and unbalanced game (for the child formerly known as a forum bad word as well as the fiancee, bruahahahahahahahahah!)

[Weirdo]

....I have no idea what you're asking. My mind keep focusing on the word secession, and wondering if you're trying to incorporate 'Mechbusters into an American Civil War scenario.

[Fireangel]

OK, assuming I'm looking at a aerotech sheet printed from HMaero, with the movement chart under the sheet stats, how will a Mechbuster (moving at 4/6 max because of bomb load)'s movement look in print, if the fighter is starts the game at Velocity 2... how much MP per turn do i spend

1) to maintain that velocity thru out the secession?

Every turn, you lose half your velocity, so if you start at velocity 2, at the start of next turn your velocity will be 1. To maintain your velocity of 2, you need to spend 1 MP, so that at the end of that turn you will have velocity 2 and start next turn at 1. Lather. Rinse. Repeat.

2) how much MPs do i have left per turn for allowance for maneuvers, if i wish to have as much loiter/harassment time for ground support attacks?

Assuming a 5/8 thrust 'Mechbuster, you will have 4 thrust (aero units use thrust, not MP) available at 1 fuel point per thrust point AND an additional three thrust for 2 fuel points per thrust point.

Don't forget that you can make free turns based on velocity and hexes moved.

I picked the Strategic Ops pdf only recently for the Repair Rules (TU for who ever told me to get it!) so I've only glanced at the aerospace side, totally unready to use those rules (yet)...

Low Altitude aero movement rules are in TW.

[cray]

Every turn, you lose half your velocity, so if you start at velocity 2, at the start of next turn your velocity will be 1.

To be a bit more clear, I'd phrase that as, "...at the EDIT start EDIT of the next your velocity MIGHT fall to 1 UNLESS you spend 1 thrust point to offset aerodynamic drag." Aircraft don't actually go through a see-sawing velocity.

The reason for this is air movement in BT is modeled on a modified spacecraft movement system. In BT, when a spaceship in open space expends 1 thrust point in 1 turn, and then expends no more thrust, the ship will continue to drift along at 1 hex per turn forever. If it spend 3 thrust points in a later turn, it will then start moving 4 hexes per turn, and continue drifting at 4 hexes per turn forever.

BT air movement is the same except for the addition of aerodynamic drag (which removes half your velocity the following turn, round down, unless you fight it with more thrust). A fighter that expends 4 thrust points on Turn 1 will move 4 hexes. On turn 2, if its engines are idled, it will slow down from drag so that it only covers 2 more hexes (for a total of 6). On turn 3, if the engines are still at idle, it will slow down to 1 hex per turn (half its previous velocity of 2), covering a 7th and final hex. On turn 4, with a velocity of 0, it will stall and plummet.

Or that fighter could then sustain its velocity. On turn 1, it spent 4 thrust points and accelerated to 4 hexes per turn, covering 4 hexes. On turn 2, it can sustain that cruising speed by expending half its velocity in thrust: 2 points will keep it moving at 4 hexes per turn.

This system means a fighter can reach a velocity equal to twice its thrust points. A 'Mechbuster, limited to 6 thrust per turn, could spend 6 thrust on turn 1 to reach a velocity of 6 and cross 6 hexes. On turn 2, it could expend 6 more thrust. 3 thrust points would be spent offsetting drag, so it would reach a velocity of 9 (6 from turn 1, -3 for drag, plus 6 thrust = 9), and would have crossed a total 15 hexes by the end of turn 2 (6 on turn 1, 9 on turn 2). On turn 3, it could expend another 6 thrust points to reach velocity 11 (9 velocity from turn 2, -4 for drag, plus 6 equals velocity 11). On turn 4, it could expend another 6 thrust points to reach velocity 12 (11 velocity from turn, -5 for drag, plus 6 equals velocity 12). The 'Mechbuster couldn't accelerate any further because the drag at velocity 12 is 6 points, which is all its engines could give.

That's quite different than ground movement, where momentum is not simulated.

[pensiveswetness]

Every turn, you lose half your velocity, so if you start at velocity 2, at the start of next turn your velocity will be 1. To maintain your velocity of 2, you need to spend 1 MP, so that at the end of that turn you will have velocity 2 and start next turn at 1. Lather. Rinse. Repeat.

Assuming a 5/8 thrust 'Mechbuster, you will have 4 thrust (aero units use thrust, not MP) available at 1 fuel point per thrust point AND an additional three thrust for 2 fuel points per thrust point.

Don't forget that you can make free turns based on velocity and hexes moved.

Low Altitude aero movement rules are in TW.

so in that scenerio above, i spend at least 1 TP to maintain constant velocity of 2, but if i wanted to increase velocity to 3 or 4, then i spend in addition to the 1 TP to pay for maintaining Velocity, i spend 2 or 3 to increase my velocity (thus next turn i now pay 2 TP to maintain Velocity 3 or 4)

Now what benifite does going faster do to me? speed doesnt provide a to-hit penalty in Ground-to-air attacks from battlemechs or other types of units able to shot at a aerospace fighter on the Battletech-scale map does it, asides from the Angle-of-Attack bonus? or is it that I would need certain speeds in order to pull off the various manuevers?

(TUs for the replies... i think Custer would have a different ending had he have Mechbusters on the high, honestly...)

To be a bit more clear, I'd phrase that as, "...at the standard of the next your velocity MIGHT fall to 1 UNLESS you spend 1 thrust point to offset aerodynamic drag." Aircraft don't actually go through a see-sawing velocity.

The reason for this is air movement in BT is modeled on a modified spacecraft movement system. In BT, when a spaceship in open space expends 1 thrust point in 1 turn, and then expends no more thrust, the ship will continue to drift along at 1 hex per turn forever. If it spend 3 thrust points in a later turn, it will then start moving 4 hexes per turn, and continue drifting at 4 hexes per turn forever.

BT air movement is the same except for the addition of aerodynamic drag (which removes half your velocity the following turn, round down, unless you fight it with more thrust). A fighter that expends 4 thrust points on Turn 1 will move 4 hexes. On turn 2, if its engines are idled, it will slow down from drag so that it only covers 2 more hexes (for a total of 6). On turn 3, if the engines are still at idle, it will slow down to 1 hex per turn (half its previous velocity of 2), covering a 7th and final hex. On turn 4, with a velocity of 0, it will stall and plummet.

Or that fighter could then sustain its velocity. On turn 1, it spent 4 thrust points and accelerated to 4 hexes per turn, covering 4 hexes. On turn 2, it can sustain that cruising speed by expending half its velocity in thrust: 2 points will keep it moving at 4 hexes per turn.

This system means a fighter can reach a velocity equal to twice its thrust points. A 'Mechbuster, limited to 6 thrust per turn, could spend 6 thrust on turn 1 to reach a velocity of 6 and cross 6 hexes. On turn 2, it could expend 6 more thrust. 3 thrust points would be spent offsetting drag, so it would reach a velocity of 9 (6 from turn 1, -3 for drag, plus 6 thrust = 9), and would have crossed a total 15 hexes by the end of turn 2 (6 on turn 1, 9 on turn 2). On turn 3, it could expend another 6 thrust points to reach velocity 11 (9 velocity from turn 2, -4 for drag, plus 6 equals velocity 11). On turn 4, it could expend another 6 thrust points to reach velocity 12 (11 velocity from turn, -5 for drag, plus 6 equals velocity 12). The 'Mechbuster couldn't accelerate any further because the drag at velocity 12 is 6 points, which is all its engines could give.

That's quite different than ground movement, where momentum is not simulated.

very cool! TU! Now in terms of hexs, we're on a typical sized battletech map, with each hex, is a actual BT map (God POV) and using the Straight Movement Table (TW Pg 85) to determine how far i travel before being able to perform a manuever or simply using my free movement to change my facing/flight direction (since we're in atmosphere, not space). i use blank BT map sheets shrunk down to a single sheet of paper... if that large enough to track and move aerospace no currently on the BT ground map?

[Fireangel]

To be a bit more clear, I'd phrase that as, "...at the standard of the next your velocity MIGHT fall to 1 UNLESS you spend 1 thrust point to offset aerodynamic drag." Aircraft don't actually go through a see-sawing velocity.

Well, if you have to make it clearer...  :D

Yeah. That's what I meant. I was talking in game terms, but it still sounds like putt-putting.

 A 'Mechbuster, limited to 6 thrust per turn...

6? Isn't the 'Mechbuster a 5/8 thrust beast?

[Weirdo]

It is, but he did mention before that his was limited due to carrying bombs.

[Fireangel]

It is, but he did mention before that his was limited due to carrying bombs.

Ah! Bomb's in my brain then for not having seen it.  :-X

[pensiveswetness]

its cool. the Fiancee had a MSF before damage said Flight Level -1 (ejected)... now before i give up the lap top to the little minion.... Normally you make ground strike attacks from Altitude 1 to 3... can you strike a Dropship (presuming the zero in the strike math is the level-10 dropship you're trying to avoid to slam into?

i got like 3 hours to find out, since we paused th game due to her, uh, going to work, and we're starting where we left off and she has a mechbuster coming in this turn...  O:-)

[Weirdo]

The DropShip's on the ground? Then it's treated exactly the same as any other ground target. Remember that Elevation and Altitude are very different things, and almost never interact. Regardless of the elevation of the target, the allowed altitudes for a strike attack are always 1-3 above the Altitude of the ground(usually zero).

So if you have an infantry platoon you want to shoot at, the allowed Altitudes are 1-3. If you then turn around and try to shoot at the DropShip sitting right next to the infantry platoon, the allowed Altitudes are still the exact same 1-3.

Long story short: Unless the DropShip actually lifts off and leaves the ground, you make exactly zero adjustments for the ship's height.

[cray]

very cool! TU! Now in terms of hexs, we're on a typical sized battletech map, with each hex, is a actual BT map (God POV)

Correct. In standard low altitude movement, each air hex is equal to about 1 ground map, or 500m across. (The high altitude/space map is 18km per hex.)

and using the Straight Movement Table (TW Pg 85) to determine how far i travel before being able to perform a manuever or simply using my free movement to change my facing/flight direction (since we're in atmosphere, not space).

Correct and correct.

i use blank BT map sheets shrunk down to a single sheet of paper...

That works. Unless you get into minis, scale's not an issue in BT.

if that large enough to track and move aerospace no currently on the BT ground map?

If you keep your speed low so you can turn 180 degrees in a few hexes.

[pensiveswetness]

thanks for the replies (and verification of the math in my head!). For the record, because it was really late, heres what happened:

Dropship one never survived (because for the senerio, both dropships's FCS were crippled by partisans [3 crits] but with the chance for repair teams to fix a box each turn after turn 12 on a dice roll of 11 or higher but taking a FCS crit before any successful repairs would kill the repair crew, which happened) because later on, when a flaming wrech of a mechbuster hit the cracked shell of said destroyed Onion, er Union... well i sort of imagined that 6200+ points of fuel when introduced with 7 HE bombs and 3 Inferno bombs... would obliterate the airfield, badly damaging the remainder Union and of course, KIA both the ejected Mechbuster pilot and a ejected Stalker-3H pilot, who punched from ammo boom...

in other words, the Finacee had a fine time playing.  :))

the other dropship's nose guns was the reason why a outbound Mechbuster (which was 0 & 3 for Ground Attack) was a flaming wreck...

[cray]

well i sort of imagined that 6200+ points of fuel when introduced with 7 HE bombs and 3 Inferno bombs... would obliterate the airfield, badly damaging the remainder Union and of course, KIA both the ejected Mechbuster pilot and a ejected Stalker-3H pilot, who punched from ammo boom...

200 tons of liquid hydrogen are actually a fairly small explosion threat, more of a severe fire hazard. Even then, it can be hard to ignite. When the Challenger broke apart in 1986, its 600 tons of liquid oxygen and 100 tons of liquid hydrogen mixed (producing the large white cloud) and then had solid rocket boosters (still burning) fly through the cloud without much ignition.

You're more likely to get a localized explosion (the relatively dense liquid hydrogen being initially unable to get sufficient oxygen for complete combustion), followed by an intense local gas fire as the hydrogen evaporates through the wreckage.

Of course, that's less fun than a big explosion and you were playing a game, not performing physics homework. Go with what's fun. :)