With Shuttle Craft figured out, I am turning my attention toward space fighters. Are they an essential platform? Are they a viable platform? Two different questions either one of them could be no.
So the first thing is: what is a fighter craft? I am defining a fighter as a single person piloted craft with a mission endurance of less than 12 hours. For planning purposes, the pilot will be maintained in a pod with an atmosphere, and thus not have to wear a flight suit. We'll ignore ejection seats because, frankly, a person in a space suit would pretty much require the equivilent mass of life support equipment as is installed in the ship. If anything was to be ejected, it would probably be the fuel and weapon stores. Without a radio, chances of recovery for a crewman would be zilch.
You really can't have a single pilot craft with an endurance much more than 12 hours because the pilot is going to have to sleep and use the restroom at some point. And by the time you add those amenities, you might as well build a larger craft.
A single human pilot, his/her life support equipment, and all of the furniture for the cockpit I estimate to be around 900kg. If we place them at the center of mass of the spacecraft, they will experience very little in the way of G-forces during turns.
For weapons, I was thinking that the ship could carry one or two 20mm autocannons. It would carry about 10000 rounds of ammo, and we would also need a radar. All of that gear would probably weigh in at another 900kg.
For the ship itself, I was picturing a sphere. The smaller the better. The pilot would strap themselves into a standing position. In my world lore these are called "Cofpits". They feel more like coffins than cockpits.
And if someone wants to play with my math: a spreadsheet.
A vessel 3 meters in diameter would weigh in at about 30 metric tons. This is about the somewhere between the max takeoff weight of an F-16 (16800 kg) and an F-15 (32000 kg). I worked out the math based on 3 "stages" of flight:
|Stage||m0 (kg)||mf (kg)||propellant (kg)||deltav (m/s)||Burn Distance (km)||Max G||Burn Time (minute)|
I'm going to work backwards from the premise. I am a science fiction author, after all. Instead of designing the interceptor to match the threat, let's see what it's performance tells us it would be an answer to.
As we can see, this craft can travel a tremendous distance in a relatively short spurt. Compared to a larger vessel, with massive fuel tanks, this little craft has a deceptively small DeltaV. But that DeltaV is expended over minutes not days. In 7.42 minutes it is 1400 km away from it's base or home ship. It arrives with enough fuel to completely reverse course and fly in the opposite direction, and an equally fast speed. It can then bleed off that speed and match trajectory with its base or home ship.
In the canon that is emerging from me head, both sides of the conflict have painful memories of the Battle of Psyche, fought decades before. In that battle both fleets were destroyed. ISTO's fleet was destroyed in harbor by a surprise missile attack. Krasnovia's fleet was destroyed by nuclear standoff missiles fired from space stations.
Long story short, before the conflict it was thought that only a direct hit from a nuclear tipped torpedo would be deadly. In the vacuum of space, a nuclear detonation makes a pretty cool light show. But no blast. It was thought that a sufficiently powerful battery of Point Defense Cannons (PDCs) could knock out any incoming missile. Nuclear weapons, being somewhat finicky, wouldn't detonate if you shredded the launch vehicle.
This turned out to be a wrong assumption. Many missile guidance systems could detect either the incoming fire, or the penetration of the rounds, and fire the warhead anyway. In other cases the fusion fuel the missiles utilized turned into a blast amplifier for a nearby controlled detonation. "Close enough" turned out to be hundreds of kilometers not tens of meters.
The range at which a PDC could engage a nuclear missile were entirely too close to prevent that missile from doing its job. Even with a 1000 m/s muzzle velocity, it takes time for the bullet to fly out to meet its target. And then there is the problem of trying to lead on a target which is actively maneuvering.
The Badger is an ugly, ugly hack. Basically a point defense cannon strapped onto the same propulsion system as a nuclear missile. It is designed to be deployed rapidly, thrust out to meet the missile, and defeat it far, FAR outside the range where it could do any harm.
A Badger, if you took it up to full speed, is 33x faster than a speeding bullet. The nearly spherical shape is to provide as much surface area for shielding to cover a minimal volume of vital area. The tight form maximizes the vehicle able to roll and turn in any direction equally. The Badger carries a powerful radar system, which coupled with a fly-by-wire control makes it into a deadly precision gun platform.
It's weapons are a simple as they are effective. The same 20mm cannon used on other point defense systems. One gun fires forward, one gun fires behind. This allows the pilot o engage a target while either decelerating or accelerating.
A piloted system was selected because any computer based weapon system might be jammed or fooled by a novel development in evasion technology. It was also considered important to have a human behind the decision to fire. The cannons on the Badger can effectively destroy any small vessel. Later deployments would also show they can inflict mission kills on larger vessels, when targeting propulsion or sensor systems.
There are no windows on a Badger. The pilot sees the world through two different DRADIS arrays. One faces forward, one faces aft. This is, again, to allow the craft to attack effectively in either the accelleration or deceleration phase of flight.
Kraznovians have a similar class of interceptor they call the "Kugelfisch" (Puffefish). The Pufferfish lacks the rear firing cannon, replacing that weight with more fuel, and thicker plating on the front of the craft. Their weapon is placed dead center on the craft, with the pilot and ammunition balancing each other. Their ships also do not utilize cable recovery, so they lack the recovery plate protruding from the bow.
Badgers and Pufferfish are designed to pop out, destroy a target at arms length, and return. They both have been employed to intercept pirates and other intruders. However, fleet engagements are fought at ranges of millions of kilometers. These craft are only effective at thousands of kilometers. The main limiting factor is keeping the crew alive, awake, and sane for durations longer than 24 hours. Even assuming a one-way suicide mission, a Badger using all of its thrust would only reach a speed of 20800 m/s. That is fast enough to cover the distance from the Earth to the moon (3.85e5 km) in 3 hours. But to cover the distance from the Earth to Sun (1AU or 1.5e8 km) it would take 50 days. Even if the battle was half an AU away that is still 25 days. And, keep in mind, without any fuel left to maneuver or return home.
Fleets that get close enough for their interceptors to start exchanging shots are close enough to have destroyed each other with their standard weapons.And I have a few other thoughts on weapons...