Steve Jackson Games Forums - Orbital Base Jumping

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Re: Orbital Base Jumping

Something like adding the Soft landing system (SS p24) maybe a good idea, if you could add it to a powered suit. it doesn't nessesarily need to be stated for its DR verus re-entry, just that it is used up or discarded after re-entry.

Re: Orbital Base Jumping

Quote:

Originally Posted by Tai (Post 1102481)

I'd like him to be able to put some combat use out before he lands, but he wouldn't have to be firing from the moment the jump started - if the capsule breaks up a mile above the ground, that's plenty high enough for some light air support.

So why not use the scheme similar to the one in Tiberian Sun?

Example build:

Code:

TL        Spacecraft                dST/dHP        Hnd/SR        HT        Move        LWt.        Load        SM        Occ        dDR        Range        Cost

10        Marine Drop Pod                15        0 / 4        12        3G/0.15        10        0.5        +4        10        3        $1.265M



Length: 10 yd. (30 ft.)   Crew Requirement: 1 [2]   Power Points: +4 / -5   Air Performance:  Speed: 4,300 mph / 3G / 0.15 mps   Hnd/SR: +4 / 4



[edit]Streamlined and winged, mostly for manoeuvre purposes.[/edit]



Systems:

Front:

1. Armor

2. Soft Landing System

3-6. Passenger Seating.



Central:

1. Armor.

2-6. Major Battery - Turret (with gunner each).

Core: Control Room



Rear:

1. Armor

2-4. Defensive ECM.

5. Engine (e.g. Chemical Rocket)

6. Fuel for said engine

Core: small Antimatter Reactor

The thing carries 10 marines (1 pilot, 5 gunners already shooting when the thing is in the air, and 4 sitting just in case), has Hnd+4 for those aerial dodges, and packs a high-G (but low-endurance) drive for emergencies, breaking, and course-corrections outside atmosphere.
The ECM helps prevent it from being easily hit.
It is assumed that no more than 4 turrets require energy. If none do, you might want to replace the reactor with something. OTOH, if you have cheap/good Reactionless drives, you might want to skip the fuel and maybe buff the reactor.

For long-range superscience descent, you may risk replacing an ECM station with a cloaking device, the AM reactor with a Vacuum, and the drive with a Cold Inertialess drive., reducing the heat signature (before entering atmosphere) to a mere +3, which with SM+4 makes the stealth capsule capable of being dropped from somewhere outside the solar system, and only being discovered upon reentry.

If you're feeling extra nasty, and know your battlesuits can survive landing in a zone with some fallout, you might want to arm the turrets with AM missiles or bombs, and launch them upon entering atmosphere, thus tying up the planetary defense forces with chasing them instead of you. Now that inspires terror.

Re: Orbital Base Jumping

That design works scarily well. Not quite what I was after, but I'd argue it fits my needs better if anything - specially since now I think about it, a solo marine in a battlesuit is still gonna get shredded pretty fast... But that, that's something the players can ride in on with a team providing covering fire. (Knowing the squad leader, with Ride of the Valkyries blasting out of a sound system somewhere)

I'd have to tweak it a bit to make it fit TL9^, I think - I forget exactly what TL antimatter reactors come in, but I'm pretty sure TL9 isn't it. Still, very very fun...

Re: Orbital Base Jumping

Quote:

Originally Posted by vicky_molokh (Post 1102500)

Marine Drop Pod

I'd just like to warn against dropping antimatter onto a planet in something as flimsy as a marine drop pod. I can see those getting shot to pieces in huge numbers. A MHD turbine or two will make the pods safer and more affordable (read: disposable).

Re: Orbital Base Jumping

Quote:

Originally Posted by Tai (Post 1102448)

Also, no word on the big question about the battlesuit - would it be reasonable to put enough DR on that to survive re-entry, and if so would it be plausible to 'add' Ablative DR to an existing suit or would it need to be built into it?

Not reasonable or plausible, no. Check that wikipedia article I linked. Re-entry shields made of mere material have to be the right shape to do the job, and many designs require shedding the ablative heat shield before it can heat through. You want to put your man-shaped battlesuit behind a proper blunt-cone re-entry shield.

Also, I tell you again that material that makes an effective re-entry shield doesn't necessarily have any DR at all against bullets or axes. And it is ablative in rather a different sense from GURPS armour.

Re: Orbital Base Jumping

Quote:

Originally Posted by Allu (Post 1102650)

If 4e had capacitors, I'd put one in instead. But as it stands, one can get rid of the reactor entirely by using missiles and/or conventional guns.

Re: Orbital Base Jumping

Quote:

Originally Posted by vicky_molokh (Post 1102658)

If 4e had capacitors, I'd put one in instead. But as it stands, one can get rid of the reactor entirely by using missiles and/or conventional guns.

Yeah, given that Spaceships makes no difference between conventional and electromagnetic guns in terms of damage I'm inclined to agree. I'd use the generator space for a Cargo Hold with provisions and/or ammunition.

Also, minor nitpick: Switching places of the soft landing system and the ECM makes sense from a safety standard. But that's just me being pedantic.

Re: Orbital Base Jumping

EM guns have twice the velocity, and thus twice the damage MULTIPLIER compared to conventional (unless you're flying so fast that it doesn't matter, which the pod likely doesn't).

It's hard to tell which hull will be facing upwards anyway: do you engine-break, manoeuvre horizontally, or try to keep the speed fast until you're low enough?

Re: Orbital Base Jumping

I forgot about EM guns velocity, thanks for catching that. Even a conventional 2cm VRF gun will do 30d(2)pi++ (not dDamage) per hit, that'll cover just about anything that a drop pod should be able to destroy. For everything else there's missiles.

My point with the reorganization of the systems was that you're likely to be taking fire from the direction you heading in (otherwise you're really in trouble) and that that direction is unlikely to be the rear. I wouldn't want the soft landing system in the hull section facing the enemy.

Re: Orbital Base Jumping

Quote:

Originally Posted by Pomphis (Post 1102483)

You only need DR for aerobraking on the underside if the reentry vehicle is designed properly (like an apollo capsule). Given what a battlesuit looks like and that´t won´t be very stable in the air you probably have to protect all sides. So IMO a battlesuit should use some sort of drop capsule, which doesn´t have to be fully enclosed. More like an armored shield to stand or kneel on plus a cage structure with fins. Armoring the suit would probably add significantly more weight.

Good points, though considering that you want the re-entry vehicle to decelerate as hard as the crew can stand (to minimise the time you are in vulnerable re-entry mode and the amount of territory you need to overfly to make a landing) I'd put a drop trooper on his back in a crash couch.

Quote:

Originally Posted by Allu (Post 1102680)

My point with the reorganization of the systems was that you're likely to be taking fire from the direction you heading in (otherwise you're really in trouble)

How to you figure that? the angle of re-entry is likely to be less than 2° and probably less than 1°, which suggests to me that ground fire will be coming from pretty damned close to square on the beam.

Quote:

and that that direction is unlikely to be the rear.

Why unlikely to be the rear? Absent superscience, spaceships in general spend as much time travelling backwards as forwards. Given the high accelerations involved in re-entry you are definitely going to want your re-entry craft laid out like a ship that accelerates in the opposite of the direction you move in when re-entering.

Quote:

Originally Posted by vicky_molokh (Post 1102667)

It's hard to tell which hull will be facing upwards anyway: do you engine-break, manoeuvre horizontally, or try to keep the speed fast until you're low enough?

No, definitely not. You try to shed speed as high as possible, because travelling at multiple kilometres per second through the thick air of the troposphere generates ram pressures that greatly exceed the strength of any plausible material, besides decelerating the vehicle so sharply that the crew would be severely injured. If you have the delta-v to engine brake, by all means do so. With 8 km/sec of delta-v you can re-enter from LEO on a parachute without a heat shield.

The problem with aerobraking high and fast is that you get a lot of heat that way, and less slowing by ram pressure. On the other hand, neither craft nor crew can handle the ram pressure of re-entering any steeper than a couple of degrees, so you just have to solve the problem of the heat.