Fighters/PT Boats in the Traveller Universe

[Marcatlas]

Could you make your mind up.

First you say achieve a geosynchronous orbit above your drop point -

WRONG!!!!!!!!!!!!!! I NEVER wrote "geosynchronous orbit". Quote me or admit you didn't comprehend the simple sentence I wrote I DID write.

 

[mike wightman]

Happy to oblige, here is where you wrote it.

Right. Only a malfunctioning person would chuck pods out at orbital velocity. You come to geosync over the target area and drop

Now before you get all pedantic:

WRONG!!!!!!!!!!!!!! I NEVER wrote "geosynchronous orbit". Quote me or admit you didn't comprehend the simple sentence I wrote I DID write.

I admit you didn't write the words "geosynchronous orbit", but in writing "You come to geosync over the target" you are either being incredibly vague or not aware of how the majority will interpret your intent.

You are misusing the term "geosync", or rather not defining what it means in your head, since it means something specific in terms of geosynchronous.

 

[McPerth]

Please, gentler words are equally efective and use to bring less conflict (both, among users and with rule 6)

 

[Carlobrand]

So, the part everyone knows: geosynchronous orbit is the orbit at which the velocity you need to maintain a stable orbit without engines is the same as the velocity at which the planet turns. You therefore appear to hover - or make little figure eights - above the same spot on the planet. Now the important part: that's almost always within short range of planetary defenses. Jump troops are used when you want to insert troops with better odds of most of them getting to ground than you'd have if you tried to bring in your troop ship or your lenders and APCs. So, your troop ship is out there past about 50,000 km, probably close behind some warship with good screens and anti-missile defenses, spitting out little half dTon eggs with troopers in them, hoping they'll be too hard to spot and too numerous for the opposing forces to counter.

It's possible out there to maintain a geosynchronous position using your drives to hold position, but it is not ideal. Why? It's the phonograph problem. If you are maintaining position with respect to a point on the planet's surface, you are like the ant on the outside of the phonograph looking inwards at the ant huddling close to the record label. You have a lot farther to go around the circumference of the phonograph than he does around the circumference of the label. To make one full circuit in the same time as him, you have to go much faster than him.

Now let's look at the drop capsule. He's going as fast as the ship that releases him. He's also falling. He has to slow his fall enough that he hits atmosphere at a safe fall rate. He also has to slow his forward motion as he falls in order to maintain his geosynchronous position (not orbit) as he falls. That's a lot of energy. Actually, his least-energy approach is if the ship that launches him is moving at the same speed as the planet rotates. From the ship, it will look like the planet is turning very fast, but that is only because the planet's surface is inscribing a much smaller circle than the ship is. In actuality, the planet is turning at the same velocity as the ship so that, by the time the capsule reaches the outer atmosphere, the capsule is moving at the same velocity as the planet's surface, over the target, and needs only use its drive to slow its fall and deal with any winds it encounters.

So it's just a matter of the launching ship, 50,000 km+ out, moving at the same velocity as the spinning planet so the capsule falls and hits atmosphere at the same velocity as the spinning planet, and timing the launch so that this happens when the capsule is above the desired target,

 

[Condottiere]

Stealthed spacesuit.

And heatshield.

 

[kilemall]

Oooh not my understand of what a drop would be. At all.

Just first principles, you are at geosynchronous orbit, you are going x km to maintain that position over the planet. You exert thrust to ‘go down’, unless you counter that orbital velocity you will be retaining it but at lower altitudes you will have less orbit to travel, thus lose that geosync position and making faster orbits the closer to atmosphere you get.

So you will have the orbital vee and downward thrust vee plus more gravity the closer you get to contend with, making for one helluva jerk once the capsule hits atmo and slows down.

No matter what combo you do to come in, the atmospheric friction slowdown is going to exert some serious impact. We’re talking starship grade inertial compensation to avoid spam effects, or at least a powered suit coupled with a grav harness perhaps.

That geosync distance is a long way too, depending on how fast you are incoming, can accelerate coming out of the ship then have to decelerate to survive atmo and/or surface impact.

Knowing what speed your capsule can survive hot entry and decel is going to define your approach.

Easiest way is to have the capsule fire decel to slow down the orbit and drop alt through gravity. Given that every second up there is a recharge cycle on PD lasers, you want minimal hang time.

I’m thinking optimal approach is dropship heads straight at planet about 3Vee, capsules launch at 20000 km, drop ship accels to avoid hitting planet while capsules fire 1/2 turn 6G decel at 10000km. 300 plus seconds to 10000km (maybe less depending on gravity). Then another 400 plus seconds getting down to a comfy 1-2Vee, atmo not such a big hit.

Other combos possible, but any semi realistic reentry is going to have such narrow windows or advanced capabilities to get our hero dirt side in one piece.

 

[Carlobrand]

Oooh not my understand of what a drop would be. At all.

Just first principles, you are at geosynchronous orbit, you are going x km to maintain that position over the planet. You exert thrust to ‘go down’, unless you counter that orbital velocity you will be retaining it but at lower altitudes you will have less orbit to travel, thus lose that geosync position and making faster orbits the closer to atmosphere you get.

So you will have the orbital vee and downward thrust vee plus more gravity the closer you get to contend with, making for one helluva jerk once the capsule hits atmo and slows down.

No matter what combo you do to come in, the atmospheric friction slowdown is going to exert some serious impact. We’re talking starship grade inertial compensation to avoid spam effects, or at least a powered suit coupled with a grav harness perhaps.

That geosync distance is a long way too, depending on how fast you are incoming, can accelerate coming out of the ship then have to decelerate to survive atmo and/or surface impact.

Knowing what speed your capsule can survive hot entry and decel is going to define your approach.

Easiest way is to have the capsule fire decel to slow down the orbit and drop alt through gravity. Given that every second up there is a recharge cycle on PD lasers, you want minimal hang time.

I’m thinking optimal approach is dropship heads straight at planet about 3Vee, capsules launch at 20000 km, drop ship accels to avoid hitting planet while capsules fire 1/2 turn 6G decel at 10000km. 300 plus seconds to 10000km (maybe less depending on gravity). Then another 400 plus seconds getting down to a comfy 1-2Vee, atmo not such a big hit.

Other combos possible, but any semi realistic reentry is going to have such narrow windows or advanced capabilities to get our hero dirt side in one piece.

The awkward part of this is not having the drop ship destroyed with its battalion still aboard, which is why I think launching from outside short range is preferred. Also, a thousand stealthed half dTon targets are a lot harder to detect and target, with less impact to the mission if some are destroyed, than a single large ship. A half dTon one-man battery powered capsule with chaff and extensive ECM, possibly including something similar to that chemical chill can out of CT Book 4, and possibly including decoy capsules, would be a far more difficult target than a large ship with a fusion power plant.

 

[atpollard]

The awkward part of this is not having the drop ship destroyed with its battalion still aboard, which is why I think launching from outside short range is preferred. Also, a thousand stealthed half dTon targets are a lot harder to detect and target, with less impact to the mission if some are destroyed, than a single large ship. A half dTon one-man battery powered capsule with chaff and extensive ECM, possibly including something similar to that chemical chill can out of CT Book 4, and possibly including decoy capsules, would be a far more difficult target than a large ship with a fusion power plant.

Thus the SOP to glass worlds from the safety of the OORT Cloud.

 

[Rupert]

You're not going to be dropping onto worlds that have defences that necessitate dropping from 50,000 km out. Not unless your marines are okay with a suicide mission, anyway. You'd not be able to get in there to retrieve them.

Drops will be for hits on those few worlds that can mount a credible defence against ships landing, but not against those that zip through orbital space without loitering, and which have defences that can then be suppressed (probably by the assault force) long enough to recover the assault forces or to reinforce them with conventionally landed troops.

It's a small window, more common in times and places like the New Era than during the clash of empires.

 

[Dragoner]

While I dearly love Starship Troopers imtu there are drop ships ala aliens more like futuristic higgins boats and choppers to provide support. Marines could drop in though that is more likely a commando raid, such as taking eben emael https://en.wikipedia.org/wiki/Fort_Ében-Émael even that was done by gliders.

 

[atpollard]

While I dearly love Starship Troopers imtu there are drop ships ala aliens more like futuristic higgins boats and choppers to provide support. Marines could drop in though that is more likely a commando raid, such as taking eben emael https://en.wikipedia.org/wiki/Fort_Ében-Émael even that was done by gliders.

When I tried a Commando Raid PbP right here on COTI [LINK], we used an improved Scout Ship to run the gauntlet and crash landed. It was a LOT of fun.

 

[Carlobrand]

You're not going to be dropping onto worlds that have defences that necessitate dropping from 50,000 km out. Not unless your marines are okay with a suicide mission, anyway. You'd not be able to get in there to retrieve them.

Drops will be for hits on those few worlds that can mount a credible defence against ships landing, but not against those that zip through orbital space without loitering, and which have defences that can then be suppressed (probably by the assault force) long enough to recover the assault forces or to reinforce them with conventionally landed troops.

It's a small window, more common in times and places like the New Era than during the clash of empires.

As I recall, the only provision for recovering paratroopers back in the day was to push an army forward until it could join with them. I presume jump troops have a similar job: disrupt and disorganize the defense, seize key pieces of real estate until the regulars can get there. That's likely to include the sensor installations the deep mesons depend on for targeting and the missile sites that might target inbound landing boats and grav APCs, thereby facilitating the landing of the forces that will make it possible for them to be reinforced or retrieved.

There is no "zip(ping) through orbital space without loitering" without facing at least one shot from a deep meson, given short range covers a 50,000 km radius of the planet, least of all if your intent is to drop off pods for re-entry. You either slow enough to release them, release them far enough away that they can brake for re-entry on their own, or watch them burn up on re-entry; there's no mention of hypervelocity re-entry provisions. Interestingly, I can design a drop capsule in MegaTrav that carries a battery-operated 6g standard grav thruster for braking (or accelerating), but that just means the faster you go, the farther away you have to release them so they can slow for re-entry. That makes the whole business of zipping rather pointless since they still have to cover tens of thousands of kilometers on their own while braking for re-entry. Might as well have them handle the acceleration stage too.

Per canon, the job of the pods is to penetrate the planetary defense. They're equipped with chaff, extensive ECM, and decoy capsules for the job. They're a lot smaller than your zipping troop ship, a lot harder to detect, a lot harder to hit, and a lot more numerous. Their odds of surviving to land are a good deal better in those capsules than on a troop ship.

As far as I know, the New Era did not exist when Striker, the source of the drop capsule details, was published.

 

[Rupert]

A deep meson gun will have lots of sensors, probably all hooked into the planet's equivalent of the internet, as well as by dedicated channels, and you'll have to knock out tons of those sensors to get any sort of blind spots. I generally assume that if a world has a functioning deep meson gun of any power you won't be invading until it's somehow neutralised, and dropping troops probably involves giving the gun(s) lots of apparently higher value targets to distract them while the dropships drop/land troops. Ideally after you've found the site (somehow) so the drop can be to neutralise it.

 

[Condottiere]

Might be easier to deliver a container full of troops to the loport.

 

[Rupert]

Might be easier to deliver a container full of troops to the loport.

I'm completely onboard with the best way of deal with deep meson sites being skulduggery and cheating. If you can neutralise them before they world even knows it's at war, everything becomes so much cheaper and easier.

 

[mike wightman]

Which is probably as easy as disabling the entire USA nuclear triad...

 

[Rupert]

Which is probably as easy as disabling the entire USA nuclear triad...

That would depend on the world, but there's a reason that Hi-pop Hi-TL worlds are very, very hard to capture.

 

[Marcatlas]

I admit you didn't write the words "geosynchronous orbit",

Correct. So your follow on comments were incorrect.

 

[Marcatlas]

Stealthed spacesuit.

And heatshield.

When you crash into an atmosphere at high speed and create a mini fireball, if you are doing that type of entry, your IR and radar sig goes through the roof.

 

[Carlobrand]

That would depend on the world, but there's a reason that Hi-pop Hi-TL worlds are very, very hard to capture.

Meson guns aren't terribly expensive on a planetary budget, and neither is mining holes. They can be built as early as TL 11-12. Mid-pop worlds can afford a few, and rules that apply to ships don't necessarily apply to planetary militaries: importing a few top quality computers and techs to maintain them to improve meson gun accuracy is cheaper than building the mesons themselves. These few guns are formidable to a fleet but can be overwhelmed by large numbers of small landing boats, so they're backed by missile batteries which are of little use against large warships but quite numerous and effective enough to make a boat landing a bloody and expensive affair. These are a prime target for jump troops, these and sensor arrays and command centers and anything else that will sow confusion and paralyze the defense just long enough for the boats to follow and land the main force.

The problem with painting mesons as an impenetrable defense is it makes worlds of even a few million into fortress worlds. These are the worlds you target with jump troops, worlds that might have no more than a few such guns and militaries small enough that the number of troops a fleet can transport can have an actual impact. Here a few battalions of battle-dressed jump troops can mean the difference between getting the rest of your troops to ground and seeing half of them destroyed before they land.

If you're going to give jump troops their due, then you've got a battalion of special forces who won't be detected until they reach the atmosphere, possibly not even then if those capsules can land quietly on gravs rather than make a showy reentry. If you don't want to give jump troops their due, then there's really no point in having them.at all - or in launching wars since you now have scores of fortress worlds to contend with where you once had only a few.