How do fighters launch from large craft?

[Aerohead]

The vision of fighter launch is touched on in another thread, but I wonder.  I understand the rules mechanics of fighter launch, but how do they do it?  Is it a large control arm that releases them into space?  Is it a rail system, ala Galactica?  Is it an active thrust off an internal platform?  Does it differ ship to ship?

I much prefer the "rail gun" launch.  Is this even covered in canon?

[cray]

Some details are given in Strategic Operations, which discusses the facings of the large craft from which the fighters are ejected. (They come out sideways to avoid the large craft from ramming the fighter from behind [drawbacks of front ejection] or incinerating the fighter [drawbacks of rear ejection]).

Specific details of how fighter/small craft bays are left, er, unspecific. This gives writers leeway to describe different launch mechanisms for different ships with different factions. A Federated Suns civilian JumpShip with a pair of small craft is unlikely to have the same launch/recovery mechanisms as a battle-tested Vengeance-class fighter carrier DropShip. Perfectly acceptable mechanisms include: catapults, the fighter's own reaction control system (RCS), or deck crew can push it out the side.

Some generalities, though:

1) BattleTech fighters will not be launched out the nose of a large vessel. While a nose launch would be safe if the carrier is coasting and the fighter is ejected by catapult or RCS, other situations result in bad things. If the carrier is running its engines (likely in a combat situation), it will be easily accelerating at 1G or more - i.e., adding speed faster than an F15 or F22 with its engines firewalled, possibly faster than the shuttle when its main tank is nearly empty. A fighter might launch with its own engines running, but BT fusion engines are such that a fighter could evaporate (or at least horribly maul) the carrier if it did so. On the other hand, a catapult launch at 120mph+ with the fighter's engines off only buys the fighter seconds before an accelerating carrier rams the fighter from behind. 2.5G = 0 to 120mph in 2.4 seconds.

2) BattleTech fighters might be dropped out the stern of the carrier, but they'll quickly need to dodge to avoid the kilotons-per-second drive plume if the carrier is running its engine. (If the engine is off, see point 1).

3) This leaves a sideways launch with some "oomph," such as from a catapult or fighter RCS. However, note that BT spacecraft are not very deep - you won't get a long, Battlestar Galactica-type tunnel launch (see DropShip cutaways in DropShips & JumpShips). You'll get a quick heave-hoe from the short fighter bays to get your fighter out the ship and with a little sideways velocity to keep you clear of the carrier's drive plume. Ideally, the fighters will quickly pivot to get their carrier-wrecking asses aimed away from the carrier.

4) Civilian carriers are unlikely to launch craft frequently under thrust, so they don't need catapult assists. They can puff their way out with RCS.

[NightmareSteel]

Could see a rotation-assisted fling for bays mounted on grav decks.

[cray]

Could see a rotation-assisted fling for bays mounted on grav decks.

I don't see fighter bays being mounted on gravdecks. While launching wouldn't be too bad for the fighter, docking would be impossible short of stopping the gravdecks or docking elsewhere and having fighter-sized elevators running hundreds of meters to the gravdeck.

[Goose]

Think there might be some kind'a gauss/ elctromag tech for launching and landing? Being about to do both with the flatop underway is a pretty tall order . . .

[cray]

Think there might be some kind'a gauss/ elctromag tech for launching and landing?

For launching, sure, in some military fighter bays.

For landing, I don't see how that'd work.

[verybad]

Probably a simple electric catapult, probably not as powerful as those on a modern day carrier. All it has to do is get the fighter clear of the ship, then it can accelerate under it's own power. Might feel more like a strong elevator than a carrier catapult. No reason for somethign to be uber if it's not necessary.

[Goose]

For launching, sure, in some military fighter bays.

[gets visions of retractable rails for said shuttle [drool]]

For landing, I don't see how that'd work.

The mag deck on teh Bebop?

[cray]

The mag deck on teh Bebop?

I was figuring thrusters and docking clamps.

[NightmareSteel]

Nah.  Landing is most likely going to be very similar to modern day aircraft carrier landing- relative speed difference would be a bunch lower though.

Something like an extensible tailhook mounted on the bottom of an ASF, something like a docking boom that extends loops of cables, probably three or four.  As soon as contact between the tailhook and the cables are made, first the "loose" cables start spooling in quickly (to get them out of the way), then the boom draws the ASF in to a docking boom/landing rail or something.  This would probably lead to a fighter sized elevator leading to the docking bay.  Or the boom itself might be an arm that could "deposit" the hooked fighter into the bay.

The only other alternative I could think of would be side mounted recovery bays leading into the hangars.  These recovery bays would have a very similar tailhook/cable setup.  Recovery would mean: ASF matches vectors with carrier, approximately in line with bay.  ASF slowly thrusts toward carrier to locate recovery bay.  Tailhook deployed, come in for recovery.  The entire time, the carrier could not maneuver, and the helmsmen and engineers would be ready to pour on max thrust at a moments notice, in order to facilitate aborting a landing.

Bear in mind, I used to work on a carrier, so I might be suffering from "that's how it has to work" tunnel vision.

[cray]

Nah.  Landing is most likely going to be very similar to modern day aircraft carrier landing- relative speed difference would be a bunch lower though.

Something like an extensible tailhook mounted on the bottom of an ASF, something like a docking boom that extends loops of cables, probably three or four.

BT DropShips have never evinced external docking arms for fighters. The Monolith JumpShip has docking arms for DropShips, but the few descriptions of fighter landings indicate they end the docking bay directly. The description of the Vengeance DropShip's stern docking bays seems to emphasize this direct-entry method.

And I wouldn't trust a cable system in free fall (the landing rules make it hard to dock with an accelerating ship). Once you grab something with a stern, ventral-side hook in free fall, with nothing else holding down the rest of the fighter the nose should pitch up, the landing gear will come off the deck and the fighter will collide with the ceiling of the landing bay unless you're using RCS jets to keep the fighter down.

Easier just to flutter in on RCS and push the fighter down to the deck until something grabs it or the DropShip lights its engines to supply "gravity."

This would probably lead to a fighter sized elevator leading to the docking bay.

Few BT DropShips have fighter bays large enough for elevators. The Union, for example, has published pictures of its fighter bay deck showing direct entry/exit doors.

[NightmareSteel]

The point for the cable was either to A) pull the fighter to the boom, or B) pull the fighter to the landing deck.  What else can grab the fighter?  You mentioned docking clamps, but I'm a little fuzzy on how that'd work.  Docking collars/clamps make sense to me for an external launch, and the only other thing I can think of offhand that might be clamp-like would be an ****** big electromagnet in the deck.

I guess coming in on RCS could work, but that's risky.  We use

RE: Elevators- yeah, only WarShips need apply.  I was thinking from the WarShip perspective for all of this, and it's readily apparent that most of it is N/A for Dropships.  Backreference tunnelvision  :-[

[Ruger]

In AeroTech 2, there is a picture of a pilot approaching his fighter in a hanger bay. The fighter is on a catapult, with the landing gear retracted, and held in place from above by retractable arms. It appears that both the arms above, and the catch from behind the fighter are on tracks that end almost at the bay doors (although granted, the tracks for the overhead arms is not a plainly drawn as the ones built into the floor for the catapult's launcher...and given tha the pilot appears to be walking normally (as if held down by gravity), it is likely that the ship is under acceleration at the time of the picture.).

This picture is on page 69 of AeroTech 2: Revised.

Ruger