Fighter Sizing

[Matt123]

Okay then, as it stands, there's really no reason for the Rampart fighter to exist other than to mop up after the big boys. I realize there's nothing in the rules for this, but with TL 15 computer tech do you think there would be a program that would allow the Rampies to swarm around the home ship or something like a big space Growler and benefit from their higher computer level?

Maybe a computer program that allows a computer to run at the half of the power of the original with a penalty for range?

As Ico suggests, there are a lot of other activities the Rampart can do very well and it is very cost effective in those roles. For example a Ramparts 2bis computer costs 18MCr while a Model 9 computer costs 140MCr plus the cost of a Power Plant to provide the 12EP's it requires. When chasing Zhodani privateers or scumbag Imperial opportunists, 6 Ramparts are by far your better bet than a single high spec fighter.

There are numerous house rules gamers have proposed for fighter computers, but I'll point you first to JTAS 27 with the write up of the Rampart which introduces the idea of a flight combining weapons to increase its battery size. And also to JTAS 14 which gives optional rules for High Guard fighters. Neither are accepted as Canon rules, but they are still interesting.

If you do go down this path be aware that there are several schools of thought as to whether fighters "need" the help. If you start a thread trawling for house rules avoid the "Fighters are broken" approach...

 

[aramis]

Like you I only have access to the '81 version of the rules. In that the fighter is described as (Book 2, p18 & TTB p63);

I'm not sure how to interpret that as meaning the fighter occupies a 10-ton bounding box, but actually displaces less than 10 ton in volume. Surely a 10-ton hull is intended to mean a 10-ton hull?

Unless we are at cross purposes with what Pat means by a "bounding box". I understood him to mean the volume occupied by a theoretical box which contains all of the craft including extremities (eg: winglets, spiky thing on the nose, etc) and regardless of the actual shape of the craft. For example a sphere of x dtons and diameter y would occupy y^3 dtons, the difference between the sphere dtons & bounding box dtons being waste space. To leave no waste space would require a box shaped fighter with no extremities.

I do accept what you are saying about the 2000ton carrier being pure book 2, I probably should have checked first. *** (Pat, pure Book 2 designs can be built up to 5000 ton and hold small craft on a 1:1 basis. A 10dton fighter can be housed within 10dton, it being obviously a very snug fit. A tunnel mount or other snug arrangement, but definitely not a typical hanger. My comments assumed a High Guard design),

The TTB illo shows something looking like a VW bug crossed with a Buck Rogers fighter...

So, yeah, the bounding box probably is bigger, but it's also probably rigged for external hardpoint docking, rather than hangarage. Tube or tunnel.

 

[PFVA63]

Hi

[Hi, I just found my old calcs and it looks like I made a big mistake (accidentally multiplied by two) so I have corrected the stuff below to now show what I think are the correct numbers (in bold). Sorry for the mistakes.]

Here is a model I put together a long time ago, when I was first trying to learn to use the modeling program Hexagon.

If I am remembering correctly, it more or less shows a fighter like small craft scaled to be approximately 5 dtons in volume, but at the time I was assuming a dton equaled 13.5 cubic meters. So if assuming a dton is 14 cubic meters, the craft is actually about 4.75 dtons.

I tried to make it look a little similar to a Rampart, but as I realized how much bigger I'd have to make the hull to get the craft closer to the size I wanted, I began to make the fuselage broader and fuller. Also, since Hexagon does a nice job of fairing out shapes, the winglets and tail fins were all made as if they were stretched out from the fuselage, as opposed to making them look like an appendage to the craft.

In general, with the wings and fins fully extended it would take a box about 18.6 m long by 9.3m wide by 3.0m high to fully enclose (or bound) the shape. I think that works out to 518.9 cubic meters or 37.1 dtons, which is about 781% the size of the craft.

If we were to assume that the winglets and tail fins could be folded close to the body then I think that you could fit into a box about 18.6m by 3.72m by about 2.25m, or 155.7 cubic meters (11.1 dtons) or about 234% the size of the original craft.

One thing that I had tried to do with the craft was to keep its folded height less than 2.5m to allow it to fit in a single deck height on its mother ship, allowing some space for deck structure. The extra 0.25m difference (2.5 -2.25) hopefully may allow for a bit of clearance will moving or maybe for short extendable landing pads to support the craft in the hangar.

This does raise the question though about fitting the craft into a hangar, since the overall folded height of 2.25m is less than the standard deck height of 3m, that would mean that the craft actually takes up more deck squares than the 22.2 squares you would expect based on its notional folded bounding box size of 11.1 dtons. The actual deck area for the bounding box of the folded craft would be 18.6 by 3.72m or 69.2 square meters which is equivalent to 30.75 deck squares (which would equate to about 15.4 dtons for a 3m high deck).

Also, it may make sense here to also include a little margin around the sides for when the craft is moved about. If you assume about 0.1m all around (~4 inches) the revised bounding box for the folded craft is 18.8 by 3.9 by 2.45m or 179.6 cubic meters (12.8 dtons) though in terms of deck squares it would be about 32.6 deck squares.

Beyond this, any additional room for access and maintenance or arming would likely also need to be considered.

Finally, at only 2.25m high, on a potentially 2.5m clear height deck, there will probably be issues with getting into and out of the cockpit, as the top of the canopy is very near the roof of the hangar, if you are assuming a 1 deck high hangar. I suppose that you could make the canopy slide back, but then the pilot would seem to have to crawl over the fuselage to get in. In general, it kind of got me thinking as to why space fighters would have a canopy at all. Maybe they should just be fully enclosed and use sensors to give the pilot an overview of what is around him.

Anyway, just some additional thoughts and info.

Regards

Pat

PS. I agree that for a small carrier external attachment probably makes more sense than a hangar, I'm just trying to kind of rationalize in my mind what some of the issues are with trying to carry alot of small craft on a relatively small ship.

 

[PFVA63]

Hi

To add to the above, since the shape of the fighter above seemed to require such a large bounding box even when folded, I had also tried looking at other shapes.

Here's a kind of simple truncated ellipsoid shape with short tail fins. One image shows the craft with a bubble canopy (and looks a little "Spaceman Spiff"-ish from some angles) while the other shows it without any canopy.

The intent on this craft would be to have the tail fins fold over for stowage.

For reference I also have a couple small renders showing my to notional fighters in comparison to a modern day F-22 fighter, and a 1950-70's era F-104 fighter for comparison. I'm not 100% sure that everything is scaled exactly in these two images but I think that they are close.

Regards

Pat

 

[PFVA63]

Hi

I just found some old calcs that I once did, and for the F-104 aircraft in the post above (the one with the orange tail and wing tip tanks) the total enclosed volume (excluding the wing tip tanks) is about 1.61 dtons.

I included the F-104 in the above images because in some ways due to its simple fuselage, and stubby wings and tail surfaces it reminds me a bit of the Traveller Rampart type fighter.

If you try to put the plane into a box equal to its length times its wingspan (without the tanks) times its overall height, you get a volume equal to about 36.1 dtons (or 2242% its enclosed volume). Though, some of the overall height is due to its relatively long landing gear, so if this were a Traveller type space fighter you might be able to assume shorter landing gear and save some space.

As an alternate idea, I took a look at what the volume would be of a rough octagonal prism shape that could be used as an envelope for the airplane. Here I basically drew a straight line from the tip of the nose to the forward point of the wingtip on each side of the aircraft, then another straight line from the forward point of the wing tip to the aft point of the wingtip on each side, and from there another straight line from that point to the aft point of the tip of the horizontal tail (on each side), and then finally from that point to the aftermost point on the plane.

Taking this area times the overall height of the plane I came up with a volume of about 21.8 dtons, or 1354% of the planes enclosed volume. Though, as above if this plane were to be used as a Traveller type space fighter you might be able to shorten the landing gear a little to reduce the total enclosed volume a bit.

Anyway, looking at this kind of stuff really makes me think that for a complex shape like the F-104, eventhough it has relatively stubby wings and tail fins the ratio between its enclosed volume and its bounding box volume (or its "Octagonal envelope" volume) is very very large.

As such, in Traveller, if we are going to assume that a 10 dton fighter (or any other small craft) is really meant to have a hull that encloses 10 dtons of space, if it is a complex shape like the F104 (or say the existing Traveller Rampart type) fighters then saying that you need 130%, 200%, or even 400% of the small craft's enclosed volume for a hangar may be much too small. For a simpler shape like a cylinder with a rounded nose (or a squished cylinder - with an oval cross section - and a rounded nose) the 130, 200 or 400% values may make more sense.

This has really gotten me thinking that maybe Traveller type fighters should be a much simpler shape than some of the existing illustrations have shown Rampart or even some of the stuff in recent MGT publications.

Anyway, just some additional info to ponder.

Regards

Pat

 

[dean]

I definitely feel the shapes as illustrated have been way too complex for a "space fighter". The sheer power these things can generate preculdes the need for lift surfaces, and indeed could simply be lifting bodies just for efficiency.

Add antigravity for precise control and VTOL capability for atmospheric landings and presto.. Wings disappear.

Canopies? Unnecessary and add a point of vunerability. Everything is fly by wire anyway, and a some retractable cameras for "landing" and recovery would be fine, although I'd imagine computer control would be safer, faster, and more efficient overall anyway.

 

[McPerth]

I definitely feel the shapes as illustrated have been way too complex for a "space fighter". The sheer power these things can generate preculdes the need for lift surfaces, and indeed could simply be lifting bodies just for efficiency.

Add antigravity for precise control and VTOL capability for atmospheric landings and presto.. Wings disappear.

Canopies? Unnecessary and add a point of vunerability. Everything is fly by wire anyway, and a some retractable cameras for "landing" and recovery would be fine, although I'd imagine computer control would be safer, faster, and more efficient overall anyway.

I can only agree with you if you disregard the ground support role most of us also give to fighters.

If atmospheric high performance flight is also expected for them, I guess some wings (even small ones, more properly fins if you want) would help a lot in thight maneovers, AFAIK (I'm not expert on aerodyinamics).

About canopies, I've always thought that just camera (or scope) sight is too focused, giving sometimes disadvantage in combat (at least when combat is developed at visual range, of course that has no effect beyond that).

So I think your points may be good if the fighter is designed only (or mostly) for space combat, but reduces greatly (too so for my liking) its role as ground support. We must take in consideration that when Imperial Marines (or other jump troops, for what is worth) make a planetary assault, their main support may come from those tiny, so criticized for space combat, fighters.

 

[Matt123]

We must take in consideration that when Imperial Marines (or other jump troops, for what is worth) make a planetary assault, their main support may come from those tiny, so criticized for space combat, fighters.

So long as the support is given well away from any ground or orbiting space defenses (most often around around transport nodes, population nodes, military nodes, communication & power generation nodes, etc). Ground based defenses will have access to the best computer available at the defenders tech (and possibly imported or cutting edge computers at higher tech).

Meaning a TL15 Rampart operating over a TL12 environment will give away a +5 to hit DM to the defenses. Plus any restrictions you place on the Ramparts ability to use all of its Agility-6 in atmosphere. At worse a ground or orbiting 100 ton missile bay will need (2+, computer diff +5, size mod -2, agility -6) 5+ to hit. And a single hit will inflict 9 criticals...

 

[Antony]

Though from a different ruleset. In FF&S hangers come in two sizes, the minimal hanger is 200% the volume of the carried craft and the spacious 400%. The smaller hanger increases the level of difficulty to do maintenance, repairs etc by 1 level.

Incidently the TNE version of the Rampart is 210 cubic meters volume (15 dt) and is 15 meters in length.

 

[McPerth]

So long as the support is given well away from any ground or orbiting space defenses (most often around around transport nodes, population nodes, military nodes, communication & power generation nodes, etc). Ground based defenses will have access to the best computer available at the defenders tech (and possibly imported or cutting edge computers at higher tech).

Meaning a TL15 Rampart operating over a TL12 environment will give away a +5 to hit DM to the defenses. Plus any restrictions you place on the Ramparts ability to use all of its Agility-6 in atmosphere. At worse a ground or orbiting 100 ton missile bay will need (2+, computer diff +5, size mod -2, agility -6) 5+ to hit. And a single hit will inflict 9 criticals...

I guess I didn't explain myself as well as I thought.

When I talked about support, I meant tactical precision support (think on Stukas or Gunships). I assume orbital superiority is achieved before landing begins, and that means orbital defenses are already not a danger, as aren't most of ground anti-space defenses.

IMO (argeable as always) at this phase of the war the rules applying would be more like air combat/grav vehicles rules than space combat rules. I don't know the importance Striker (assumed to be the CT applicable rules) gives to computer in this case, so I thought about MT grav vehicle combat rules and COACC.

 

[dean]

I guess I didn't explain myself as well as I thought.

When I talked about support, I meant tactical precision support (think on Stukas or Gunships). I assume orbital superiority is achieved before landing begins, and that means orbital defenses are already not a danger, as aren't most of ground anti-space defenses.

IMO (argeable as always) at this phase of the war the rules applying would be more like air combat/grav vehicles rules than space combat rules. I don't know the importance Striker (assumed to be the CT applicable rules) gives to computer in this case, so I thought about MT grav vehicle combat rules and COACC.

A fighter that tries to all things does none of them well.

In my thoughts about it, a ground assault force will have dedicated ground support like grav tanks for that sort of thing. I just don't see using a highly specialized and expensive craft like a space-combat fighter as being something a cogent commander would send down into a gravity well to use as a precision strike support craft. The weapons available really aren't suited to the mission, and indeed a missile armed craft would be near worthless in the role.

Just my humble opinion.

 

[McPerth]

A fighter that tries to all things does none of them well.

But does all of them acceptabiliy, and is more likely to be available than specialized crafts/vehicles.

And what is seen already in this thread (and various others, for what is worth) is that one of he things Rampants don't do wel is space combat against military ships, so perhaps we should scale down its mission to minor engagements and ground support.

The fighter given in MT Fighting ships as space combat fighter is 20 dton and has a 9 rated computer (and costs a little more than MCr 120 each). (note: I've not reviewed its design so I cannot tell you how reliabel is, as most designs in this book are heavily flawled).

 

[dean]

But does all of them acceptabiliy, and is more likely to be available than specialized crafts/vehicles.

And what is seen already in this thread (and various others, for what is worth) is that one of he things Rampants don't do wel is space combat against military ships, so perhaps we should scale down its mission to minor engagements and ground support.

The fighter given in MT Fighting ships as space combat fighter is 20 dton and has a 9 rated computer (and costs a little more than MCr 120 each). (note: I've not reviewed its design so I cannot tell you how reliabel is, as most designs in this book are heavily flawled).

Forgive me, but in my view, if something is not done "well", then it's not acceptable.

And if you are lugging around a spaceworthy fighter to have it play a ground support role, that is to me contrary applicaton of design. Sure, sometimes you might *need* to do it, but to actually consider that as a viable secondary role?

A space worthy fighter ought to: First, Be able to engage likely opponents on at least close to even footing; second, be able to conduct related vacuum environment operations like scouting, space patrol, pirate interdiction, etc; third, be able to engage and damage escort size ships of likely opponent fleets; and lastly, engage in ground support operations versus on world or atmospheric targets - in small unit actions. Any large scale operation involving planetary assault should bring their own low orbit/suborbital support like grav tanks or atmo fighters for that specific role.

Tha availablity of "specialized crafts/vehicles" will be directly proportional to the effort aimed at the objective. Wholesale planetary assault will have those resources allocated and available. Rooting out a smugglers base on a backwater ice world will not, but since your squad of space fighters can take out thier fleet 1:1, sure, go ahead and use them for that...

Furthermore, the kind of training a specialized space combat pilot would have would place them in a disadvantage versus an atmospherically trained ground defense pilot would have, along with being in a craft not intended for the task makes it seem to me unwise indeed.

 

[McPerth]

Forgive me, but in my view, if something is not done "well", then it's not acceptable.

That may be a matter of doctrine thinking, but that's (IMHO) the same as saying that a unspecialized doctor may not be a good doctor, because he is not fully trained on any speciality, or that a multi role combat aircraft may not be worth, as they are inferior to equivalent tech interceptors in that role and inferior to equivalent tech bombers in that other role.

And if you are lugging around a spaceworthy fighter to have it play a ground support role, that is to me contrary applicaton of design. Sure, sometimes you might *need* to do it, but to actually consider that as a viable secondary role?

A space worthy fighter ought to: First, Be able to engage likely opponents on at least close to even footing; second, be able to conduct related vacuum environment operations like scouting, space patrol, pirate interdiction, etc; third, be able to engage and damage escort size ships of likely opponent fleets; and lastly, engage in ground support operations versus on world or atmospheric targets - in small unit actions. Any large scale operation involving planetary assault should bring their own low orbit/suborbital support like grav tanks or atmo fighters for that specific role.


Tha availablity of "specialized crafts/vehicles" will be directly proportional to the effort aimed at the objective. Wholesale planetary assault will have those resources allocated and available. Rooting out a smugglers base on a backwater ice world will not, but since your squad of space fighters can take out thier fleet 1:1, sure, go ahead and use them for that...

In MT (not in other versions), the tree first missions you tell here require at least a 20 dton craft, as smaller than that are vehicles and use grav movement rules, so needing a gravity well to be fully effective, while 20+ dton allow them to have thrusters and so being able to deep space maneovering without penalty.

On the ground support role, atmospheric crafts need ground bases, so limiting their use (on the first stages of the war, at least), while grav tanks lack the deep interdiction capability a fighter may give (as long as you care a little about collaeral damage, if you don't, ortillery may assume that role).

I'm not an expert on military matters, but I know in war you must work too often whith what you have at hand, not with what you'd like to have, and I guess that would be even more true when communications are the nightmare they are assumed in Traveller. This makes multi role stuff a worthy asset.

You have quite more fighter carring starships than other more specialized vehicles carring ones, so the probability of having fighters to support ground operations is quite higher than having more specialized vehicles. IMHO if the fighter designer forgets that role, he's limiting your options to an unacceptable level.

I agree with you, though, that their better used in small unit tactics than in large unit strategy (but so are too the gunship helicopters I cited above, though the fact I forgot the word helicopter may have confused you)

Furthermore, the kind of training a specialized space combat pilot would have would place them in a disadvantage versus an atmospherically trained ground defense pilot would have, along with being in a craft not intended for the task makes it seem to me unwise indeed.

That's only true if you assume they're not intended for this mission. I keep thinking that's one of the role (along with the others you cited above) fighters are designed for.

Sure they can be fighters without this (seccondary) mission in mind, but this will only make them worth building (more economic) if they can be unstreamlined, and if so they won't either be able to base on planets, only on space stations, and I think they're better based on ground, on the planetary defense role.

 

[PFVA63]

Hi

Though from a different ruleset. In FF&S hangers come in two sizes, the minimal hanger is 200% the volume of the carried craft and the spacious 400%. The smaller hanger increases the level of difficulty to do maintenance, repairs etc by 1 level.

Incidently the TNE version of the Rampart is 210 cubic meters volume (15 dt) and is 15 meters in length.

Cool. Thanks for the additional info.

Regards

Pat

 

[PFVA63]

Hi

I think I might try and do up a new fighter, based maybe kind of the X-37B.

I guess I could drop the small wings, but I still kind of like the thought of the craft having small stubby ones. My thought is that maybe they could fold up alongside the fuselage, and the tail fins could maybe fold down, when stowed onboard. I'm thinking that maybe the winglets might be of use when operating in a gas giants upper atmosphere, either when pursuing other craft, or if lying in weight and hiding. Also, if small thrusters are located at the tips it might give some benefit in rotating/rolling the craft.

Anyway, the shape of the X-37B looks fairly full in cross section with a flat-ish bottom, so hopefully its bounding box requirements might not be so excessive in comparison to its enclosed volume, like some of the other options I've looked at.

Regards

Pat

 

[stealth]

The Ultimate Fighter:

I found a way to make a fighter that can absorb factor-9 bay weapon strikes in a fleet combat.

They say fighters only make sense at TL 8-12, but you can make a specialty fighter at TL15 that can stand in the line of battle and be effective.

It's a 99 ton rock.

At TL-15 it is possible to create a fighter capable of engaging capital ships and defeating them under High Guard/ TCS rules.

99 ton planetoid rock fighter (the Death Skull 99)

Percentage based components:

20% Planetoid hull
16% Armour f-15 (total 18 due to configuration)
17% MD-6
12% PP-6, fuel-6 for agility 6
---
65% (65 tons)

Tonnage based components:

11 Model-8
18 +9 power plant, +9 tons fuel for computer (total PP-15)
1 missle turret
3 Magazine
1 Crew stations
---
34 tons

Total: 99 tons.

The result: a 99 ton rock fighter with level 18 armour which cannot be critically hit except by spinal mount weapons. Factor 9 bay weapons have no effect, although very lucky hits from nuke bays will slowly scrub it's weapons if an entire light cruiser fires on one. And that means 3 turns of repair in reserve on it's config-7 carrier.

It can fight for 36 turns without running out of ammo or life support and needing to dock.

A group of 10 has the equivalent of a factor-7 nuclear missle battery with a model 7 computer (because it has no bridge), but still that is nothing to sneeze at.

Use them as a screen, so that that you can repair the spinal mounts on your cruisers as your take them in and out of battle.

 

[McPerth]

Sure this fighter must be hard nut to crack, but the fact of being a planetoid hull makes it unable to be mass produced, so costs and times for building them increase quite a lot. This only fact makes me wonder if they would be feasible in fleet planning as true fighters, used to operate in flights.

Also I guess there will be problems with the carriers, that would need to be specialized for those fighters, as the fact they're not standarized makes launch tubes out of place. This means they are not able to be carried by other carriers/cruisers/BBs, etc.

And, of course, you agree with Dean about ground support is not one of its roles, as it whould be not even streamlined...

On the plus side, this could be quite good in system defense (though I'd probably upgraded to SDBs, increasing its tonnage, and thus giving them more offensive turrets, but that's another discusion...)

 

[dean]

Obviously it seems to boil down to now what actually may or may not work, but design philosophy.

And I do not disagree that a ship like the Rampart is *capable* of ground support.

But a planetary invasion/ground assault in force is not the kind of militart operation that just "happens"; it's a logistically complex and demanding operation that does requiure long term planning and concerted efforts by a lot of different units. That makes these operations expensive as well. Since these are the kind of operations you absolutely will not want to have to attempt twice, having that specialized vehicle in the plan and at the disposal of the commander is essential. You will want to succeed on the first try, and you will use your planning time and resources to make sure the pieces you need will be there, especially in a Traveller universe where communications are limited and slow.

Anyway, I guess we will need to be in disagreement. Happy Travelling!

 

[McPerth]

But a planetary invasion/ground assault in force is not the kind of militart operation that just "happens"; it's a logistically complex and demanding operation that does requiure long term planning and concerted efforts by a lot of different units. That makes these operations expensive as well. Since these are the kind of operations you absolutely will not want to have to attempt twice, having that specialized vehicle in the plan and at the disposal of the commander is essential. You will want to succeed on the first try, and you will use your planning time and resources to make sure the pieces you need will be there, especially in a Traveller universe where communications are limited and slow.

I'm affraid I'm not explaining myself as well as I inetend...

When I talk about ground support, I don't meant a full planetary invasion to a well defended world (e.g. Invasion Earth), where I agree with you planning is enough to bear more specialized vehicles, be them Grav tanks, air superiority crafts, etc (though I gess fighters would end up helping them on ground support missions in this case, anyway...)

I was thinking mostly in the ground mission the cruisers carry marines for: surgical strikes, small planetary raids, oportunity targets, assaults to pirate bases, etc... Those dirtside missions would also be grateful to have some 'air support', and it's unlikely you have atmospheric craft for than on your cruisers.

About the Rampants specifically, one of the role most of us agree (or at least that's what I understand from most posts) they're not suited for is large fleet engagement. In MT their small size makes them unsuited for deep space combat, but even in CT, with their small computers, they are suicide in fleet engagements, while the damage they can be expected to deliver is negligible to none (I assume in fleet engagements most computers would be quite higher rated). So, their main role must be another if they're being built. Piracy fighting may be one, but those missions are usually left to smaller starships, not ones carring fighters. So their main role seems to be picket warning and ground support (IMHO).