[spaceships] Ohka Heavy Torpedo Bomber(TL 10/Realistic)

[adimar]

Hi all.
Here is another one of my spaceship designs this time: The Ohka Heavy Torpedo Bomber.
To understand the reasoning behind this design it needs to be understood that point defense batteries
(Fixed to the size of tertiary battery weapon on a SM+7 ship but increases the number of weapons.) can be very effective in destroying incoming missiles.
This together with the cost of missiles renders long range missile attacks practically obsolete vs. military targets.
This craft uses an Orion drive to be super armored, fast & difficult to hit.
So it can approach an enemy capital ship at close range and launch a barrage nuclear tipped missiles.
> This ship requires the armor & volume rule from Pyramid 3/34

Ohka Heavy torpedo bomber
TL 10, SM+5, Non aerodynamic
[F/1-4] Hardened Nano composite (44 dDr)
[F/5 ] 3 x Medium Battery (Fixed, High Thrust, Missile Launchers / Main Armament)
[F/6 ] Fuel tank
[F/C ] Control Room (No ejection)
[C/1-2 ] Hardened Nano composite (22 dDr)
[C/3 ] 2 x Medium Battery & SM+4 MHD turbine (Turret, Laser Very Rapid Fire/ Defensive Battery) .
[C/4-5] Defensive ECM (Total -4 to hit)
[C/6,C] Fuel tank
[R/1-5] Hardened Nano composite (55 dDr)
[R/6 ] External Pulsed Plasma (i.e. Orion Drive) (2g/24mps)

What do you think?
Adi

[weby]

Few thoughts:
-The acceleration seems low for a setting that uses orion drives. As example the TL 9 Trinity-class cruiser has 4G acceleration. So in a fight the lower TL target would be able to generate quite a lot of relative sideways vector.
-The utility of armor is a bit questionable in any encounter with any speed if the target has those huge numbers of the half ton weapons for missile defense. Conventional 8cm ballistic weapons will start to punch though the armor at the base relative velocity 50% of the time and "always" punch through at 2mps(and on average take the target to below -1*hitpoints).
-If people are throwing around nukes then even a proximity detonation from any size nuke will be devastating.

[Varyon]

Maybe I'm missing something, but lasers are much better for point defense than guns. While they do require energy, extrapolating from the Smaller Systems guidelines shows that, by reducing RoF to 2/3 normal, you could have a built-in MHD turbine that would power the system for 12 hours of continuous use. For the Ohka, Improved Very Rapid Fire Lasers instead of Very Rapid Fire Conventional would normally double your RoF, but with needing to add in the half-size MHD that means 4/3 normal, for RoF 400 for the whole system (instead of the 300 for the conventionals). This also gives at least +6 to hit (compared to proximity detonation; +10 otherwise, as small conventional weapons have sAcc of -10 while lasers have sAcc 0), and probably more (as lasers don't have to deal with relative velocity). The lasers do less damage - 6d(2) instead of ~30d (character scale, and assuming 1 mps relative velocity) - but unless you've got missiles that are extremely armored (which isn't going to leave much room for fuel, and certainly not much for a nuclear warhead), that 6d(2) should be enough to destroy them.

Also, as weby notes, all that armor isn't doing a lot for you. You could fit a lot more into the ship by going streamlined (making you harder to hit, which is more important) and replacing most of that rear armor with a magsail (which means you only need dDR 5, not dDR 50, on the rear). This can let you get away from using a complicated MHD/laser hybrid system, instead having a power plant take the place of one armor system and having that power a full-size laser battery - or maybe having multiple power plants and multiple batteries, as you'll be replacing quite a few armor systems.

[adimar]

Originally Posted by Varyon

Maybe I'm missing something, but lasers are much better for point defense than guns.

You are right, the original design had two SM+4 lasers and a SM+4 fusion reactor to power them.

Originally Posted by Varyon

Also, as weby notes, all that armor isn't doing a lot for you. You could fit a lot more into the ship by going streamlined (making you harder to hit, which is more important) and replacing most of that rear armor with a magsail (which means you only need dDR 5, not dDR 50, on the rear)

Problem with magsail is that any spacesail system it's an exposed system not protected by the spacecraft's armor. (Spaceships 1-pg.25) thus any hit would destroy this craft.
Now as for the armor not doing much, as you suggested earlier, The most common point defense weapon is a very rapid laser which does 1d-2(2) burn.
This will not even tickle the front armor of this craft (42 dDr/Hardened). To get a 50% penetration you need at least a 10mj laser which takes it out of the point defense weapon territory into the major battery firepower (To get a very rapid 10mj laser you need a 1gj battery which is a major battery on a SM+9 craft.)
Also the inclusion of 3 defensive ECM systems giving enemies -6 to hitting this craft means it would be very hard to achieve a hit with anything other than very rapid weapons.
The idea behind this craft is that it's a desperate last ditch effort by a collapsing regime to stop a vastly superior enemy by sending waves of relatively cheap kamikazes to take out it's capital ships.

Adi

b.t.w.: The name Ohka is taken from the ww2 Japanese kamikaze rocket propelled suicide gliders. Yokosuka_MXY7_Ohka

[weby]

Originally Posted by adimar

Now as for the armor not doing much, as you suggested earlier, The most common point defense weapon is a very rapid laser which does 1d-2(2) burn.
This will not even tickle the front armor of this craft (42 dDr/Hardened). To get a 50% penetration you need at least a 10mj laser which takes it out of the point defense weapon territory into the major battery firepower (To get a very rapid 10mj laser you need a 1gj battery which is a major battery on a SM+9 craft.)

If you are using non penetrating weapons like KJ scale lasers for point defense then massed armored missiles would make more sense.

The use of ballistic weapons as point defense on your craft suggested the use of such for point defense and then light vessels armor does not matter. But for 1d-2(2) energy weapons you should just armor the missiles.

A 1 ton/32 cm missile could trivially be armored to withstand such weapons from front making point defense useless.

[adimar]

Originally Posted by weby

A 1 ton/32 cm missile could trivially be armored to withstand such weapons from front making point defense useless.

I don't really think so.
If you look at a missile as a standard craft given the 10mps,5g (standard missile performance)
You need to devote:
3 slots of payload.
1 slot control center
2-3 slots for HEDM rocket engine (4g-6g)
13 slots for fuel tanks (including the x1.6 increase for 10.4 mps)
You are left with either one or no slots for armor.
Missile propulsion is calculated at the peak HEDM drive performance.

Maybe a design option could be added for heavy torpedo which has only Half the dV performance and is armored but that's not easy as well. An unstreamlined SM+2 (1 dTons) with all 6 frontal sections devoted to nanocomposite armor would have a 12 dDr frontal armor which when you take into account the (2) divisor of the laser weapon which might be barely enough to protect it from a 1d-2 frontal damage but is still totally vulnerable from the sides. (I can totally see missile defense boats parked a small distance from the capital ships who's all purpose is shooting the unarmored sides of these torpedoes.)
F[1-6] Nanocomposite 12 dDr
C[1-4] Fuel
C[5-6,c] Payload
R[1-4] Fuel
R[5-6] HEDM engines (4g, 4.8mps)
R[c] Control room

Adi

[RogerBW]

I have a similar design, but I noticed a trick: you can throw warheads from EM guns. So your SM+5 Ohka fires 5×3×16cm missiles with range X; my SM+4 Hana with a spinal gauss cannon fires 50 10cm EM rounds at range S, each with a 25kt antimatter warhead. It's less effective because it has to get in close, but it's also much cheaper.

(Since I'm working at TL11 other tech assumptions probably aren't directly comparable, but it can force a fast pass in most situations.)

https://tekeli.li/wives-and-sweethearts/ship_hana.html

[Varyon]

Originally Posted by RogerBW

I have a similar design, but I noticed a trick: you can throw warheads from EM guns. So your SM+5 Ohka fires 5×3×16cm missiles with range X; my SM+4 Hana with a spinal gauss cannon fires 50 10cm EM rounds at range S, each with a 25kt antimatter warhead. It's less effective because it has to get in close, but it's also much cheaper

In addition to the reduced effective range (and the fact that nuclear warheads, which it appears OP wants to use rather than antimatter, require a minimum size of 16cm), there's also the problem that 10cm EM weapons have sAcc -7, while at TL10 16cm missiles have (presumably; my copy of SS only goes down to 20cm for missile sAcc for some reason) sAcc of +2. With guns and missiles not having their attacks penalized by Range*, that means an equivalent missile barrage will have an MoS 9 higher, for at least 4 more hits (more if the guns didn't hit on the number, as 10cm EM Guns have Rcl 4, while missiles have Rcl 2, when firing nuclear/AM warheads).

*SS "Guns" are more like "missiles that get a boost at the start." Also, something that's never made sense to me - if guns don't have to deal with Range, where the heck does their inherent sAcc penalty come from?