Grav Tanks

[BMonnery]

Hi,

I found an old message from myself in the etranger list archive. I'd been reading a 2nd hand RCEG and thought the gravtank was odd, so posted this, thoughts?

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I thought the Grav Tank in RCEG was odd, so I modified it. Any
comments?

Trepida Grav Tank
The Trepida was the standard grav tank of the 3rd Imperium and is a
fairly standard Grav Tank, capable of being built on any TL-14 world
and equipping the Imperial Marines and many Planetary Army units. The
primary weapon is a rapid fire 25mm Mass Driver Cannon, throwing a
600g Bonded Superdense Penetrator at Mach 18 (6000 mps). A close up
weapon capable of defeating the majority of grav tanks front glacis,
and every fighting vehicles weaker side and aft armour. At longer
ranges missiles are employed. Upto 10 Javelin hypersonic missiles may
be carried. These are 250kg high speed missiles capable of engaging
armour and aircraft at long ranges. Should infantry opposition be
expected then vast numbers of 70mm rockets can be carried. As a final
holdout, and providing point defence against incoming missiles are 2
VRF Gauss Machineguns.

The Grav Tank was always acted more like an old 21st century attack
helicopter rather than a conventional "tank" of that time. Grav Tanks
are usually employed in combined arms formations with the standard
Lift Infantry Battalion consisting of 3 Lift Infantry companies in
Astrin Grav IFVs and a squadron of 14 Grav Tanks. The Grav Tanks role
is counter enemy armour, strike deep into their rear and provide
close support to the Battlesuited Infantry of the Battlegroup. Most
attacks are pop-up in nature, emerging from NOE just long enough to
unleash a barrage of missiles and 25mm fire, destroying their target
before moving back down to the safe area.

Since the fall, most Grav Tanks have ceased to function, but even a
small cache of working Trepidas can provide a huge amount of power on
a world where nothing can counter it. Since TL14 MDAC rounds are
scarce, many have been replaced with more primitive autocannon.
General Data
Tech Level: 14
Price: ~ MCr2
Size: Very Small (140m3)
Mass: 65.14 T loaded (with fuel, 400 25mm, 30,000 4mm and 2.5 tons of
launched ordnance).
Engineering Data
Power: 5.37 MW Fusion Power Plant supplying power to high-efficiency
contra-grav lifters and HEPlaR thruster generating 58.65 tonnes of
thrust (0.0123 MW excess power)
Maint: 43
Engineering Data
Controls: Dynamic-Linked, TL10+ Avionics, TL14 TF avionics, 3x TL14
Flt computer, TL10+ IGS navigation.
Comunications: 3000 km radio, 2x 3km masers.
Sensor: 3km active EMS, 30km passive EMS (Surface Search), 3000km
passive EMS (Air/ Orbit Search), 2x Wide Spectrum Viewers.
ECCM: EMM, Four decoy dispensers with 20 decoys each.
Life Support: Extended Life Support, G-compensators, one airlock.
Cargo: Negligible
Crew: 2 (driver, commander/gunner)
Passengers: None.
Armament
Offensive: Turret mount with TL14 25mm Mass Driver Autocannon, and
coaxial VRF gauss gun. One cupola, with VRF gauss gun. Ordnance Bay
(2.5 tons of tactical missiles, anti-tank missiles, rockets, bombs
etc.)
Defensive: None
Ammo: 400 rounds 25mm (5.77 tons, including carts); 30,000 darts for
each VRF gauss gun.
Fire Control: EMS Rangefinder, TL14 point defence ballistic computer.
Stabilization: Advanced

Round ROF Dam val C-B Pen Val Short Rng
Ammo Price Ammo Weight
25mm APFSDSBSD SA5 6 269-269-259-249
3000m* Cr27 (plus Cr28 for cart) 600g
4mm gauss dart 50 7 2-2-2 230m Cr.01 0.5 g
* Limited to 3000m by fire control, 6,600m by energy
Movement
Speed: 800 kph maximum speed, 800 kph cruise speed, 160 kph safe NOE
speed (3,150kph in vacuum).
Travel Move: 1260 High 640 NOE
Combat Move: 58 High 22 NOE
Fuel Consumption: 733.125 liters/hour (maneuver).
Fuel Capacity: 2052.75 liters LHyd plus 44.75 for fusion plant.
Endurance: 28 hours (HEPlaR), 1 month (reactor).
Armor
Config: Large Turret
Suspension: Grav
TF: 258 HF: 258
TS: 13 HS: 13
TR: 13 HR: 13
Deck: 13 Belly: 13

25mm MDAC: 600g Slug @6,000mps = 10.8Mj Kinetic Energy, with TL14
ammunition (APFSDSBSD) PV = 259. Input Energy = 17.28Mj, power source
= Pulse Fusion Cart pumping a HPC, 289 cartridges per cubic meter.
13.824 kg per cartridge (27.65 Cr each). HPG (5 chambers, ROF 1/
second) is 1.66 tons, costingMCr0.091. Total weapon system (exc/ fire
control) masses 2.506 tons and costs Cr180,000 just over a fifth of
1% of the cost of the Fusion Cradle Gun it replaces and is 1.25 tons
lighter.

Notes

This is based on the Intrepid in the RCEG, except I saw a couple of
glaring problems. Firstly, the mass and cost made it a prohibitive
weapons system to field. Since the majority of the cost was
apparently in the Fusion Cradle Gun, I replaced it. Casting around
for a replacement with similar performance but cheaper I got lucky on
my first attempt. A 2300AD inspired MDC was installed, built as
above. This saved a huge wad of cash, and was as effective a system,
using similar ammunition. Secondly, to bring down mass, I divided all
armour except the front by 10. This took 168 tons off the design,
i.e. almost 80% of the weight was taken providing this level of all
round protection. Current MBT have much stronger glacis for just this
reason, if we up armoured the whole M1A2 to the same standards as the
frontal glacis, it would weigh something like 400 tons (very rough
calculation), and be completely immobile. I left the 80 decoys in
place, although the number seems excessive, to survive 20 attacks is
unlikely at best. To survive, the Grav Tank must be smart, making pop-
up attacks, during which it's strong glacis will face the enemy. If
caught on a flank it will be destroyed, but that's a problem all
tanks (even the M1A2) face today. Research into tank point defence is
going on today, and it only seemed sensible to provide an ordnance
bay since there was over 2.5 spare cubic meters. The end result of
this process is a Grav Tank with more, not less, firepower. Sure, the
fusion gun was great, but we can buy 40 of these for 1 fusion gun
variant. The loss of armour gives the tank a lot more agility, with
an acceleration of 0.9G (loaded) rather than 0.23G, is faster and the
best defence is to avoid the hit in the first place.

 

[TheDS]

Unfortunately, my FFS1 book recently went MIA, so I can't look up the "original" corrected (erratified) stats; I had to make due with an uncorrected RCEG (which has a note to look at Ch#76 for fusion gun changes). But it looks like you killed off the armor on this thing and replaced the main fusion gun with a small Gauss gun. Right?

Tanks DO need side-armor and top-armor. And even some back- and bottom-armor. Top-attack is quite common in a futuristic battlefield, and had we been facing the cream of the Soviet crop instead of their fire-sale equipment in Iraq, I'm sure we'd've seen top-attack a much more heavily used option for our missiles' warheads.

There are other things that hunt tanks than other tanks, and you never know what direction they come from. Your design, with its pitiful side armor, would be EASY pickings to even unpowered infantry. Makes the tank fairly useless, relegating it to the likes of the Solomani combat sled, that thing that looks similar to a grav tank. Your tank could not survive even a glancing blow to the side.

Having the other faces be about half the main armor face was a good decision on the design of the original, as something with THAT MUCH armor is not vulnerable to much. Even a TL-15 Fusion Bazooka would not scratch it (much). Pretty much just stuff that's intended to hit heavy armor anyway.

OTOH, repalcing the gun with a Gauss cannon was probably a stroke of genius. That you went with such a small gun (25mm) seems at first to be a crazy idea, but it does give you a ton of high-ROF.

Using FFS2 to check your numbers tho (I'm much better with FFS1, but alas, it's not here atm, and FFS2 is usually the same thing) I think your numbers are mistaken. A 25mm round weighs considerably less than 600 grams (like, 300), and even if that's the right mass, your penetration is off. I've got 490 as the penetration for a KEAP round at TL-14, with 10.8 Mj of muzzle energy. This seems incredibly wrong to me. If I use 300g as the mass for the bullet, I get 5.4 Mj and pen 362, with a generous 7.2 Mw power requirement and ROF of 80 (per minute).

This tells me that the armor on this craft needs to be beefed up considerably (if my numbers are anything like correct). Taking a quick peek at Challenge 76, I see the revised pen for that fusion gun is a respectable 335. Considering it's a FUSION GUN and not a spitwad thrower, if my Gauss numbers are correct, then plasma STILL sucks. (I never created many gauss weapons, btw.)

Ok, so am I crazy? Is my calculator lying to me? Am I not using the rules to recreate your creation right?

 

[Badenov]

So, I have a tough question, and my scouring of google and the Traveller wiki has gotten me to this thread and a similar one here: https://www.travellerrpg.com/threads/traveller-military-orginization.1043/. There used to be an Imperial Marine regimental order of battle org chart on the wiki, but I can't find it now, though I found https://hemdian.com/traveller/book4/3277th-marine-regiment/ which is similar and has the same problem, which is, it contains tanks. Specifically, it references "Trepida MBT", which I had to dig around to find anything about it, and what I found (this thread) handed me a lot of stats that I don't have the books to tell me what it means, but it brought up the question:

"What role do armored vehicles have when soldiers with FGMPs for squad support can hurt anything lighter than spacecraft, and spacecraft rule the skies?" I caveat spacecraft ruling the skies with the caution that this means armoring up your fighters to ignore defensive fire. In Mg1, the only system I know, nothing on the ground (apart from the 20MCr Meson Accelerator) can hurt an armored fighter, whereas fighter-scale weapons are kind of overkill for ground vehicles. Are tanks tough enough to at least ignore FGMPs? Most of the examples in Mg1 Supplement 6 Military Vehicles are not.

Is there some middle ground where tanks have a role that they're cost-effective for? If so, what is it? In Mg1, Supp 6, if I design a tank that does much more than a TL5 WW2 relic, it's way past the cost that would be more efficiently spent on a fighter spacecraft.

 

[Rupert]

In TNE/FF&S a grav tank like the Trepida has a lot more armour than a small fighter (the Rampart is detailed, heavier ones are not) and while a heavy 50 DTon fighter might have comparable armour it will cost a lot more than a 10 DTon grav tank. As for FGMPs - none of these, nor the plasma bazooka will penetrate any facing of a Trepida at any range.

A fighter's laser will, but won't do much damage (starship lasers in TNE have amazing penetration but fairly low damage). OTOH a hit from the Trepida's main gun (and it has the fire control to do this) will wreck a Rampart, though its range is short so the Rampart can stay out of reach (though then it might have trouble getting fire control locks).

Fighters are a poor choice for ground combat. Grav tanks are a terrible one for space combat. You could make a 'fighter' that's better for ground support, but it starts looking like a grav tank pretty quickly as you'd be ditching the long-range space sensors and space combat laser for things that are cheaper and good in an atmosphere, adding NoE avionics, layering on more armour, and accepting the loss of acceleration as high-altitude straight-line speed isn't much use over a high-tech battlefield.

Now, different systems will produce different results. Striker and MegaTraveller assumed even basic spaceship armour was quite decent and spaceship weapons were massive overkill on most vehicles. On the other hand, the fusion guns TL-14+ tanks would mount were quite capable of trashing small spaceships and had huge rates of fire.

 

[Badenov]

In TNE/FF&S a grav tank like the Trepida has a lot more armour than a small fighter (the Rampart is detailed, heavier ones are not) and while a heavy 50 DTon fighter might have comparable armour it will cost a lot more than a 10 DTon grav tank. As for FGMPs - none of these, nor the plasma bazooka will penetrate any facing of a Trepida at any range.

A fighter's laser will, but won't do much damage (starship lasers in TNE have amazing penetration but fairly low damage). OTOH a hit from the Trepida's main gun (and it has the fire control to do this) will wreck a Rampart, though its range is short so the Rampart can stay out of reach (though then it might have trouble getting fire control locks).

Fighters are a poor choice for ground combat. Grav tanks are a terrible one for space combat. You could make a 'fighter' that's better for ground support, but it starts looking like a grav tank pretty quickly as you'd be ditching the long-range space sensors and space combat laser for things that are cheaper and good in an atmosphere, adding NoE avionics, layering on more armour, and accepting the loss of acceleration as high-altitude straight-line speed isn't much use over a high-tech battlefield.

Now, different systems will produce different results. Striker and MegaTraveller assumed even basic spaceship armour was quite decent and spaceship weapons were massive overkill on most vehicles. On the other hand, the fusion guns TL-14+ tanks would mount were quite capable of trashing small spaceships and had huge rates of fire.

This is very different from Mg1 armored vehicle construction, then, and much more robust. In this case, armored vehicles definitely have a role, if nothing else, in countering other similarly armored vehicles. That said, how much armor is a small fighter likely to have? How much is a lot? It seems that idea differs widely. Is the listed armor for Trepida on the same 1-15 scale as High Guard? If you allow armor for fighters, max armor is not very difficult, and wildly effective.

 

[Rupert]

In TNE/FF&S armour rating is linear with thickness, and 1cm of steel armour has AV2. A Rampart fighter (15 DTons in these rules) has 62 points of armour. A standard laser turret of TL14-15 does 30 points of damage, but divides armour by ten. Thus a Rampart getting shot by a laser can expect to take about 24 damage, which will cause one major hit (so ruin small system, degrade reactors, etc.) and a critical hit (with about the same table to roll on as HG, etc.). Don't be in small craft when the shooting starts.

Trepidas, on the other hand, started out (before they changed the damage of plasma and fusion guns) 'balanced', with enough frontal armour to resist their own main gun. It's also enough to turn hits from a laser turret into minor hits. The 250-340 odd damage (depending on variant) from a Trepida main gun is going to utterly trash a Rampart, despite those 62 points of armour. It'll take 7-8 criticals, and that'll almost certainly wreck it without having to roll for normal damage.

 

[Badenov]

So do grav tanks take over the role of modern fighter aircraft? They seem to go as fast, and to hit harder and stand tougher than fighter spacecraft.

 

[Rupert]

I believe that they are intended to follow the general pattern outlined in CT's Book 4, where grav vehicles replace tracked AFVs over the course of TL9+, and then merge with and replace combat aircraft as well.

Whether this actually works in any given edition depends on its rules for vehicles, aircraft, spaceships, etc.

 

[mike wightman]

LBB:4 Mercenary
"Tech level 11: All combat vehicles are now grav powered. The grav tank generally utilizes the more compact plasma A gun and/or tac missile racks. Very heavy grav tanks mount the plasma B gun. Light grav sleds are used for scouting, generally mounting tac missiles and autocannons.
Close support sleds mount VRF gauss guns and tac missiles. All vehicles have pronounced free-flight capability.

Tech level 12: All vehicles have sufficient free-flight performance that ground combat vehicles effectively no longer exist, having merged with aircraft. The primary weapon of the heavy gunships include plasma B guns, VRF gauss guns, and tac missiles. VRF gauss guns are also widely mounted on personnel carriers, as are plasma A guns.

Tech level 13: The first damper fields allow protracted storage and transportation of elements with short half-lives. The first major use of the damper field militarily is to enable the manufacture, storage, and transportation of 2 cm californium rounds, fired from auto-cannon mounts in remotely piloted drones. Each round is hollow and collapses on impact, the collapsed round having sufficient mass to go critical, thus causing a small nuclear explosion. More conventional gunships mount plasma C guns or fusion X guns along with missiles.

Tech level 14: More sophisticated damper fields render the californium drones obsolete.
Gunships now carry fusion Y guns or rapid pulse X guns.

Tech level 15: Gunships mounting rapid pulse X guns and heavier Z guns are virtually indistinguishable
from orbital craft. Lower performance personnel carriers mount rapid pulse X and Y guns and missile systems."

 

[Badenov]

This is very different than the Mg1 rules that the campaign I was in used. It's a very different paradigm. This answers my concerns, I suppose, if not in the way I expected.

Tech level 15: Gunships mounting rapid pulse X guns and heavier Z guns are virtually indistinguishable
from orbital craft. Lower performance personnel carriers mount rapid pulse X and Y guns and missile systems."

This makes complete sense, and explains why the Marine order of battle charts I dig up don't have dedicated air support. The armor units are the air support.

 

[mike wightman]

Note the listing of the Trepida and the Astrin as anything less that TL15 are incorrect.
The original author designed tham as TL15 and then for some reason they wwere editted to be TL14 in the DGp Book 101 Vehicles - this makes zero sense.

Canon has the Imperial Army and Imperial Star Marines circa FFW as being TL15 (there are a couple of Imperial Army units still at TL14 but they are a very small minority of the Imperial Army order of battle).

 

[Condottiere]

Depends on whether you're facing a near peer opponent, or a bunch of underfed, poorly equipped rebels.

Otherwise, you'll be hugging the deck.

 

[casquilho]

So do grav tanks take over the role of modern fighter aircraft? They seem to go as fast, and to hit harder and stand tougher than fighter spacecraft.

I am not saying what I have done is "right", but to just share, IMTU the grav tanks begin to bleed over into the role today's attack helos occupy as well as the role the tracked tanks and wheeled armored support vehicles play. The grav tanks, grav armored transports, and the powered armored troops have taken on a lot of the roles that air support and light support vehicles play today and thus why IMTU the TOEs look different than todays.

 

[whartung]

Grav vehicles make deployment and movement really easy. A troop of grav tanks can relocate very quickly.

That said, the lethality of the environment behooves the vehicles to stay out of sight. Pop up over a horizon and every missile, laser, and plasma gun will be on you like flies on honey.

Imagine a group of vehicles high tailing it down the middle of a river, an ad hoc highway, but still decent cover from the trees and canyons. Exposed, somewhat, to be sure, but they're moving at 80kph.

A fundamental tenet of warfare, is that if you want to hold territory, you have to put boots on the ground. Air power cannot hold territory. Grav Tanks and Grav APC are a mix of that. The big thing with them is that when a breakthrough DOES happen, oh boy, does it. They can MOVE, and penetrate quickly into the soft, gooey center of the enemy backfield.

In the end, though, its just a strike mission. You can't sustain enclaves of troops without the supply train.You can't leap frog from town to town and expect to keep them.

The good example of that was "A Bridge To Far" and the isolated paratroops deep in enemy territory.

So, in that sense, the boots and armor are still boots and armor, grav or not. Large, heavy, armored guns buried in a pit will always have value. They still need to present a line to secure the supply train maintaining the tip of the spear.

And even with Grav Tanks, you probably will still want lighter, cheaper strike forces for penetration. No reason to bring all of that armor and such for a quick rearward strike mission that you're not going to stick around for anyway.

They may still be armored flying vehicles, but not, perhaps, heavy MBTs.

 

[Badenov]

I am not saying what I have done is "right", but to just share, IMTU the grav tanks begin to bleed over into the role today's attack helos occupy as well as the role the tracked tanks and wheeled armored support vehicles play. The grav tanks, grav armored transports, and the powered armored troops have taken on a lot of the roles that air support and light support vehicles play today and thus why IMTU the TOEs look different than todays.

Grav vehicles make deployment and movement really easy. A troop of grav tanks can relocate very quickly.

That said, the lethality of the environment behooves the vehicles to stay out of sight. Pop up over a horizon and every missile, laser, and plasma gun will be on you like flies on honey.

Imagine a group of vehicles high tailing it down the middle of a river, an ad hoc highway, but still decent cover from the trees and canyons. Exposed, somewhat, to be sure, but they're moving at 80kph.

A fundamental tenet of warfare, is that if you want to hold territory, you have to put boots on the ground. Air power cannot hold territory. Grav Tanks and Grav APC are a mix of that. The big thing with them is that when a breakthrough DOES happen, oh boy, does it. They can MOVE, and penetrate quickly into the soft, gooey center of the enemy backfield.

In the end, though, its just a strike mission. You can't sustain enclaves of troops without the supply train.You can't leap frog from town to town and expect to keep them.

The good example of that was "A Bridge To Far" and the isolated paratroops deep in enemy territory.

So, in that sense, the boots and armor are still boots and armor, grav or not. Large, heavy, armored guns buried in a pit will always have value. They still need to present a line to secure the supply train maintaining the tip of the spear.

And even with Grav Tanks, you probably will still want lighter, cheaper strike forces for penetration. No reason to bring all of that armor and such for a quick rearward strike mission that you're not going to stick around for anyway.

They may still be armored flying vehicles, but not, perhaps, heavy MBTs.

I think I am definitely unclear on the proper paradigm for tanks and their role on the TL15 battlefield, particularly relative to Aerospace fighters from HG.

I agree about not overrunning support, but I am wildly unclear about what is vulnerable to what since I don't have all the sourcebooks, and Book 4 Mercenary doesn't say much about armor. That will play a major role in helping me figure out what's going on.

 

[Rupert]

Note the listing of the Trepida and the Astrin as anything less that TL15 are incorrect.
The original author designed tham as TL15 and then for some reason they wwere editted to be TL14 in the DGp Book 101 Vehicles - this makes zero sense.

Canon has the Imperial Army and Imperial Star Marines circa FFW as being TL15 (there are a couple of Imperial Army units still at TL14 but they are a very small minority of the Imperial Army order of battle).

No, they are TL-14 in TNE material, very clearly, and were designed as such. You might not like it, but that's the TNE reality. The TL-15 upgrade is the Norris.

As for other descriptions of it, what was the original? There's a TL-15 grav APC in Striker, but its 12 DTons, while the MT versions of the Trepida and Astrin are 10 DTons. Both are listed in the Rebellion Sourcebook as 10 Dtons and TL-14.

 

[Condottiere]

Can you fund your military?

That's supposed to be the raison d'etre of mercenary forces, to supplement or replace the military, for financial or demographic reasons.

It's quite possible your modern armoured fighting vehicle stocks fall below replacement level, in which case, you either do without, or use lower teched substitutes.

 

[kilemall]

I think I am definitely unclear on the proper paradigm for tanks and their role on the TL15 battlefield, particularly relative to Aerospace fighters from HG.

I agree about not overrunning support, but I am wildly unclear about what is vulnerable to what since I don't have all the sourcebooks, and Book 4 Mercenary doesn't say much about armor. That will play a major role in helping me figure out what's going on.

Striker has conversions for starship weapons and armor so they can fully interact.

Just the turret weapons fighters pack are pretty powerful, but they are typically lacking armor.

The example referenced is an APC but carrying a rapid fire Y fusion gun, which is good all purpose for attack or defense against missiles or shells. I wouldn’t count on fighter ship missiles getting through.

This gun at that TL is going to get several shots in, multiplying damage, and at effective range will chew through most levels of HG armor.

The armor is good too, overall HG 1-3 and I want to say 10 or so on the glacis. And it’s at MCr 5+, cheaper then the typical fighter.

The problem is the range, measured in km not planetary ranges like the powerful 250mw lasers the fighters have. This thing has .5 EP or so and just 1.5 G maneuver.

Striker vehicle direct fire control is limited whereas anything small craft can hit at 900000 km in space, working out to 900 km in atmo with the quick environment conversion. Those small craft bridges plus CT computers add up to millions of credits in electronics so that makes sense.

So even though Mr Gravvy McGravtank can punch through most fighters at short range, the fighters are going to be able to stand off and tear them up. Not to mention an actual bombardment destroyer or cruiser with all the fixings.

Lesson, have to have space superiority first.

I think you can build a fighter killer in terms of powered up weapons, or something horrible like a Californium equipped VRF gauss or mass driver against no damper fighters. The armor can be built up at cost to quite the power plant.

But that range thing should only be fixable with a like investment in starship grade fire control.

 

[aramis]

I believe that they are intended to follow the general pattern outlined in CT's Book 4, where grav vehicles replace tracked AFVs over the course of TL9+, and then merge with and replace combat aircraft as well.

Whether this actually works in any given edition depends on its rules for vehicles, aircraft, spaceships, etc.

Under MT, the Trepida/Astrin can't replace the space fighters nor the fixed wings, but they do replace the ground tanks, battle taxis, the combat helos, and maybe also the IFVs... They can take more than a typical fixed wing, but the fixed wings can usually go faster.
Why not IFVs? because the Astrin uses the battle taxi approach.

 

[Rupert]

It's similar in TNE, with the Trepida and Astrin being sub-sonic and the rules dis-allow having a large turret anywhere but locked forward above 300 km/h, limiting their combat speed further (though they're probably not going to be going fast enough when NOE for that to matter). However aircraft are very soft (as they are in MT), so they can't really go near a high TL battlefield.

As for the space fighters, unless they're equipped with the avionics for it (the Rampart is not), they can't travel NOE at a useful speed, and their weapons aren't optimised for ground combat. The Rampart, for example, can only fire its laser once every 180 seconds, though if it leaves the active sensors (which with a short range of 300,000km are massive over-powered for ground combat) it can get that down to once per 40s. So a Rampart has to fly 'high' (and thus is very vulnerable to missile and energy weapon attack) and has a poor weapon for ground combat.

Oh, and the Zho's mount X-ray lasers on their tanks with 300km in-atmosphere short ranges and rates of fire of 3-5/5 second turn and the same power as a space combat laser, giving their armoured unit integral AA and anti-orbit fire.

You can certainly build an interface 'fighter' that's useful using FF&S, but it'll end up looking like a grav tank. If you want speed, it'll be either a relatively lightly armoured one, or a very large and expensive one. It would remain vulnerable to fire when not NOE, so the extra speed probably isn't worth it.