Fighters/PT Boats in the Traveller Universe

[AnotherDilbert]

Size differences between similar types of aircraft are not that great, but if they were, it would be more appropriate.

OK.

It's relatively simple: For two craft with the same level of RCS reduction, the relation of their RCSs will be roughly equal to that of their respective surface areas. Since Traveller warships function on the same technical principles whether they are fighters or battleships, there is no reason that they should not have the same level of RCS reduction.

Edit: Sorry, the rest was completely wrong, to late in the evening... Corrected now?

OK, so signature is proportional to r² (r = radius or characteristic length of ship).

The power available to the radar, on the other hand, under the assumption that both vessels use the same percentage of their tonnage for this purpose, is proportional to the tonnage of the vessel.

Agreed, so power is proportional to r³.
Antenna size/gain increases proportional to r².

Square-cube law; the larger vessel will have relatively more powerful sensors.

But, radar equation: Detection range is proportional to power^1/4, hence r^3/4 multiplied by antenna gain, totally r^2.75?

So as r increases ten times, hence the volume of the ship becomes a thousand times bigger, detection range increases 562 times?
Radar cross-section increases proportional to r², so 100 times, hence increasing the smaller ship's detection range?

OK, so, advantage bigger ship? I missed to multiply by antenna gain before.


But what happens if a fighter squadron creates a sensor grid with a synthetic aperture? It would increase resolution more than detection range?

These values are not to be taken at... errr... face value.

OK, garbage, disregarded.

The idea of a third party, i.e. a dedicated picket ship, providing sensor data to nearby fighters would work. Of course that ship would become the primary target.

Not just providing sensor info, emitting the active signal, with the passive ships reading the echo. You gain a lot more info than passive alone?

 

[AnotherDilbert]

But, radar equation: Detection range is proportional to power^1/4, hence r^3/4 multiplied by antenna gain, totally r^2.75?

Still wrong (middle of the night)...


But, radar equation: Detection range is proportional to ( power×antenna²×signature )^1/4,
hence D proportional to r^3/4×r^4/4×R^2/4 = r^7/4×R^1/2, where R is target ship radius.

So if r = 10R, D prop 10^1/2×r^9/4 (larger ship detecting smaller ship)
or R = 10r, D prop 10^7/4×r^9/4 (smaller ship detecting larger ship)


And that can't be right... serves me right for doing math in the middle of the night...

 

[AnotherDilbert]

So if r = 10R, D prop 10^1/2×r^9/4 (larger ship detecting smaller ship)
or R = 10r, D prop 10^7/4×r^9/4 (smaller ship detecting larger ship)

Not quite wrong?

If r = sR, D prop s^1/2×r^9/4 (larger ship detecting smaller ship)
or switched, D prop s^7/4×r^9/4 (smaller ship detecting larger ship)

So, equal sized ships have equal detection ranges, sounds about right.
But, as s (the relative size difference) increases, the larger ships detection range decreases,
and the smaller ship's detection range increases. The discontinuity in the function at s = 1 (r=R) does not sound quite right.

OK, still probably wrong?

 

[Tobias]

You've lost me.

Using your simplified formula, and assuming antenna gain is actually the same for both ships and thus regarded as a constant).

50000 ton ship (r=10) vs 50 ton fighter (R=1) -> D = (1000*1)^0.25 = 5.625
50 ton fighter (r=1) vs 50000 ton ship (R=10) -> D = (1*100)^0.25 = 3.163

(Realistically, antenna gain would also be higher for the larger ship, but there is also the question on how easy sensors are to scale up, which depends on engineering constrictions and most of all signal processing power.)

 

[Tobias]

To come BTT a bit: One way to give fighters more of a ... erm... fighting chance in a HG2 paradigma would be one of my pet ideas, namely to reduce the impact of the all-powerful computer rating a bit.

 

[Tobias]

Talking about handing off sensor locks and "director ships" it may be one idea to let fighters use the computer rating of a such a ship; similar in role to an AWACS aircraft.

 

[coliver988]

Talking about handing off sensor locks and "director ships" it may be one idea to let fighters use the computer rating of a such a ship; similar in role to an AWACS aircraft.

and (not to detract too far from the subject) similar to the way the UFO Interceptors worked: they needed the Moonbase sensors for firing solutions in at least 1 episode (may have been a plot requirement though)

 

[kilemall]

and (not to detract too far from the subject) similar to the way the UFO Interceptors worked: they needed the Moonbase sensors for firing solutions in at least 1 episode (may have been a plot requirement though)

Probably most, they started tracking those UFOs way the hell out as they dropped sublight and were slowing down to do their business in Earth atmosphere.

Plus, no space to be anything but missile buses.

 

[AnotherDilbert]

You've lost me.

Well, I lost myself a considerable time ago, so that to be expected.

Using your simplified formula, and assuming antenna gain is actually the same for both ships and thus regarded as a constant).

We really should include the antenna, a bigger antenna is a more sensitive antenna, it's a key advantage for the battleship.

 

[AnotherDilbert]

You've lost me.

Using your simplified formula, and assuming antenna gain is actually the same for both ships and thus regarded as a constant).

Annoyingly I see where I went wrong, but not why...

I have to think about that before I can say anything intelligent about it.

 

[Tobias]

An additional aspect: The sensor side of things is IMHO already well emulated in CT by the computer rating. The "computer" in my interpretation includes active and passive sensors in addition to data processing capabilities. The largest computer available at a given TL represents the maximum feasible sensor size limited by the methods of antenna construction and signal processing technology.

That powerful sensors are included would also go a long way in explaining computers' size and energy requirements. Using the conversion rate first introduced in Book 4, a model/9 computer consumes 3 gigawatts (12 x 250 Mw) of power - about as much as the entire city of Los Angeles, for comparison.

Thus at the high end of the technological spectrum, the maximum feasible sensor has become so large and so power-hungry that it simply cannot be mounted on fighter craft anymore. At the lower end, fighters are quite a bit more feasible, since they can at least hit things.

 

[kilemall]

An additional aspect: The sensor side of things is IMHO already well emulated in CT by the computer rating. The "computer" in my interpretation includes active and passive sensors in addition to data processing capabilities. The largest computer available at a given TL represents the maximum feasible sensor size limited by the methods of antenna construction and signal processing technology.

That powerful sensors are included would also go a long way in explaining computers' size and energy requirements. Using the conversion rate first introduced in Book 4, a model/9 computer consumes 3 gigawatts (12 x 250 Mw) of power - about as much as the entire city of Los Angeles, for comparison.

Thus at the high end of the technological spectrum, the maximum feasible sensor has become so large and so power-hungry that it simply cannot be mounted on fighter craft anymore. At the lower end, fighters are quite a bit more feasible, since they can at least hit things.

That’s my take and I’m sticking to it.

I also have missile build rules which incorporate highly specialized computer models that end up using power and credits to achieve their performance. This isn’t your fathers cheap Cr5000 homing missile anymore…

 

[Condottiere]

The computer probably analyses sensor data for patterns.

 

[Drew]

Dumb question. Since fighters (less than 100T) are ineffective against a formation of mid to heavy-tonnage cruisers or battleships, doesn't this make the fleet carrier irrelevant in Traveller?

 

[kilemall]

Dumb question. Since fighters (less than 100T) are ineffective against a formation of mid to heavy-tonnage cruisers or battleships, doesn't this make the fleet carrier irrelevant in Traveller?

Not really, good enough to support opposed landings against ground/air/sea forces.

 

[TamsinP]

Dumb question. Since fighters (less than 100T) are ineffective against a formation of mid to heavy-tonnage cruisers or battleships, doesn't this make the fleet carrier irrelevant in Traveller?

No, it just means that their role isn't to take on capital ships - they're still effective against smaller ships like destroyers, as a screen to reduce missile salvos, for atmospheric/low orbit operations, extending the sensor net of the fleet, etc,

 

[Carlobrand]

Dumb question. Since fighters (less than 100T) are ineffective against a formation of mid to heavy-tonnage cruisers or battleships, doesn't this make the fleet carrier irrelevant in Traveller?

The Regina system per CT Book 6 (Scouts) had in addition to Regina: several million on Brumaire, several hundred thousand on Harcourt, fair size settlements of several thousand on Cent and Printemps, tens of thousands on Irgurkar around their companion star, a military base with several thousand on Gagamshir around their companion star, and a number of smaller communities. I could cause quite a bit of fuss launching diversionary attacks on those targets with fighters. The possibility would most likely prompt them to build light planetary defenses and station light SDBs on all of those, spending money and resources that would otherwise go to other priorities. I don't even need to have the carrier with me; the fact that I maintain carriers and might deploy them would have already had an impact.

 

[AnotherDilbert]

Dumb question. Since fighters (less than 100T) are ineffective against a formation of mid to heavy-tonnage cruisers or battleships, doesn't this make the fleet carrier irrelevant in Traveller?

They can't damage warships but can still screen ships, so the ships can withdraw or repair.

 

[atpollard]

They can't damage warships but can still screen ships, so the ships can withdraw or repair.

... and if designed correctly, a small worthless ship cannot be hit and can hold the "Line of Battle" single-handed in TCS as the fleet repairs [as was demonstrated in the Tournaments].

 

[AnotherDilbert]

... and if designed correctly, a small worthless ship cannot be hit and can hold the "Line of Battle" single-handed in TCS as the fleet repairs [as was demonstrated in the Tournaments].

Only against a piss-poor fleet with no accurate weapons, e.g. spinals or missile bays.

It's a design fail if you allow this to happen.

If you design a fleet that can't hit high agility ships, you lose when someone turns up with high agility ships.
If you design a fleet that can't damage high armour ships, you lose when someone turns up with high armour ships.

It's not a problem with the design or combat systems.