Revisit: Starship Flight Models / Sublight Speeds / Acceleration

[Kraven Kor]

First, see the original thread about this.

Second, I suck at higher math.


OK, here is the deal. I want to use hex maps for space combat but my weapons have ranges in the 10's of kilometers. So, I decided that for ship-to-ship combat, I want 1" to = 10km.

But my original flight model was based on normal 30" flight.

I do not want to use "inertial dampeners," and artificial gravity is going to be a fairly recent thing and not available in most ships, instead common only in the living quarters of space stations or very large vessels, or luxury vessels.

So acceleration will be an issue.

Help?


I need a way to make combat speed flight useful in combat, without having to worry too much about the g-forces exerted on the pilot.

I had kinda decided on megascale flight, but somehow I know that 10km per second was going to puree anyone inside the ship. Am I stuck being forced to use some type of "inertial dampener" to keep the occupants of such a ship alive? Do I need to not worry about using a Hex map as I can't have a 10km / phase flight speed (more for faster ships)?

I had this all nice and worked out then had to read that "how big is an inch, how long is a turn" thread

[Kraven Kor]

OK, here is what I've come up with, and of course, thanks to being a moron, it don't work...



1" = 10km.

5" Flight = 50km per phase but we want to avoid rubber science as much as possible.

Sooo...

1 Turn will be 5 minutes. 25 seconds per "phase."

Speed 4 ship with 5" flight:

100 seconds to go 50km = .5 km/s, 30 km/minute, 1800 km/hour.

1800 km/hour combat velocity.

Acceleration = Velocity in meters per second / Time in seconds
v (50000 meters) / t (100 seconds) = 500 meters per second per second... that can't be right. That is like 50 gees.


What the heck am I doing wrong?


And we haven't even hit the fun math... sublight travel.

[Outsider]

If you dont want to use rubber science, you probably arent going to be able to make a satisfying movement system. You will actually be using vector movement, if youre not using rubber.


What you got wrong was that the 500m/s figure is the ships average velocity per second over the course of 100 seconds, not its accelleration over that period.


If a turn is 5 minutes (300 seconds) then :

1 Segment = 25 seconds
4 Segments (1 phase at SPD 3) = 100 seconds.

1G = 10m/s^2

Accellerating from rest (V = 0m/s) at 1G (10m/s^2) for 100 seconds makes an ending V of 100s*10m/s^2 = 1000m/s.

The average velocity of a ship under constant accelleration will be the average of its starting velocity and its ending velocity, ie (0m/s+1000m/s)/2 = 500 m/s.

The distance travelled will be the average velocity times the time of travel. ie 500m/s*100s = 50,000m = 50km = 5".



Now, at the start of the next phase, its velocity will be 1000m/s. If it coasts for all 100 seconds, it will travel 100,000m = 100km = 10 hexes.

If it accellerates to increase its speed, then it will do the calculation above, but its starting V will be 1000m/s, and its ending 2000m/s... meaning an average of 1500m/s. which, over the course of the 100s phase, will mean that it will travel 1500*100 = 150,000m = 150km = 15 hexes.


Basically, without rubber, "flight" as we know it in HERO wont work for spaceships. You could use it to represent the ship's ability to accellerate (5" Flight = 1G accelleration) but there isnt really any upper limit on how many hexes a ship can actually move in a turn. (well, 30,000 hexes/segment = lightspeed...but that would take about a year to get to at 1G...)

[Starwolf]

100 seconds to go 50km = .5 km/s, 30 km/minute, 1800 km/hour.

1800 km/hour combat velocity.

And we haven't even hit the fun math... sublight travel.

I am not sure where your calculations are off but this is not that fast and no where near 50 G's. 1800 km/hour is only slightlty faster than mach 1. Even at standard x2 non-combat speed it only comes to slightly faster than mach 2.

At sea level and at 80 degrees mach 1 is approx 779 mph. There are 2.2 km to a mile so your 1800 kmh comes out to Approx 818 mph. For a real world comparison the F-14 Super D had a top flight speed around mach 2.4 or about 4113 kmh. Naval Aviators are tested to about 7 G's before black out. The US Military has a spy plane called the Aurora that is capable of mach 6 which comes out to an astounding 10283 kmh... very fast indeed.

There is a really cool Speed of Sound calculator here

Hope this helps

[megaplayboy]

well, in the real world, 5 or 6 Gees of acceleration is about the maximum capacity of the human body for any significant period of time. 2-3 gees is safer, but for purposes of safety, if ships have limited or no anti-grav capacity, 1.5 gees or less is safe long term acceleration. Of course, the ships would be built differently from the types you see on screen, since "down" would have to be the deck they were standing on, and "forward" would be the ceiling.

5 Gees = 100m/s^2, 100 seconds of 5 Gee acceleration will give you a velocity increase of 10km/sec, or one hex in your map. This is approximately close to the orbital escape velocity for earth. If each phase of movement takes place over 5 minutes, then average acceleration(1-1.5 Gees) would equal one hex of distance, with "emergency" acceleration/deceleration being up to 3 hexes. The ships probably could only do one or two turns per movement phase, rather than 5.
If maximum combat velocity was 30 hexes per 300 seconds, then we come up with a "speed limit" of 1km/second, about a tenth of escape velocity.
If you scale movement phases down to a minute, then you get a "speed limit" of 5km/second, or half of escape velocity.
At one move per turn, this goes up to 25km/second(about 80,000kph)
At 4 moves per turn, 100km per second, ten times orbital escape velocity, about 250,000 mph(and still less than .1% of lightspeed).
Of course, to accelerate by one hex of velocity in 3 seconds= 3.3km/second^2, or over 300 Gees of acceleration, enough to kill everyone on the ship without any rubber science protection from the consequences.

[Kraven Kor]

Rubber Science it is, then.

The only way I can make this work is with a ship that accelerates to 7500 km/s in about 3 days, and then "coasts" at cruise speed and decelerates on the other end. Same as the original thread's calculations.

Now, one thing I know for sure is the player's ship will not have the "new" gravity generators (these existed in the Miles books), so it won't have artificial gravity, but it will have to be equipped with "inertial dampeners."

What is some good techno-babble for how the inertial dampeners work? Tie it into the anti-kinetic shield technology (Magnetic Deflectors)?

[Cancer]

<technobabble>
Inertial dampening could be made to work by having a device that could manipulate the virtual neutrino sea in a specific hypervolume of spacetime. By pumping energy into the neutrinos with the appropriate energy and momentum specta, you would be able to put a compensating tensor field into the Higgs field, which is the one that produces mass. The result would be a dampening of standard inertia.

The price is twofold. First, it takes a lot of energy to do that, and it does mess up the spacetime curvature around the perturbed Higgs field. The effects are small when the preexisting curvature is modest, but if you try this in regimes where the curvature is approaching a certain critical value (that is, when the gravitational field is too high) then you risk having your entire damped hypervolume go up in a cloud of high-energy photons. {Comment: here's a hook to push interstellar combat out away from stars and/or planets, if you want that.}

Second, it can be shown that the neutrino emission is enormous, and anyone with even a 21st Century neutrino detector will be able to see you and track you while your damper is running. This isn't usually a problem since ordinarily the times you run your inertia dampers is when you're in hot combat, when most people can see everything anyway. But if you're trying to thread your way, unseen, through a minefield at high speed, you better hope no one has the thirty tons of liquid helium-3 available that makes the best high-energy neutrinoscope.
</technobabble>