Vector(ish) Movement

Blankbeard's picture
Blankbeard
January 21, 2014 - 2:05pm
http://www.starfrontiers.us/node/8008

Yet another of my ideas that I've cleaned up and would like comments on.  I wanted a system that was easy to understand and explain. The basic rules fit on a single page even with all of the examples I provided. If you use the speed chart which I admit is a little sketchy then there's an additional two pages.

The speed chart is similar to the speed charts found in Hero rules or Shadowrun. It's essentially the same thing as the impulse chart in Star Fleet Battles but simplified.

The QRR reference is to Quasi-Real Rockets, my attempt to make Knight Hawks look more realistic without turning it into something as complex as Star Fleet Battles.
Comments:

Abub's picture
Abub
January 21, 2014 - 2:30pm
That sounds interesting but I bet my players would soundly reject it as too complicated but I might give it a try.

couple of suggestions
1) Your Have your hex facing diagram which I think for this system to work is important to estabilsh for notation of ship speeds.  I would possibly remove the image of a ship in the diagram because it happens to be facing speed side A which might imply there is a referance to the orientation of the ship when I don't think they are meant that way.  The A-F speed hex sides are a universal directionality for the map (similar to a compass's N-S-E-W) so that image might confuse that.
2) You mention proportional movement.  That is fine if you have math oriented players.... but I might suggest them counting the speed movement in each direction to find the end point and then you can eye-ball the actual route from the start and end positions.  So a ship with Speeds B3 and D8 you would count from the starting spot eight in direction D and then fro there three in direction B.  The way you count wouldn't be the actual route.  When the pilot is turning and accelerating you would have to just apply the changes before you start the move which wouldn't be compatible with your speed chart system segment system.

Makes me think about this related question.  When a ship wants to stop in KH's by the rules it can simply brake or decelerate but its ADF without actually flipping over to point its main thrusters against its current motion.  That is a little unrealistic.  If you are going to bust out this vector system... you could actually handle that by making them flip first to get there whole ADF in a braking manuever.

Add the Z axis articles to this vector movement and see how many of your players heads explode!  lol



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TerlObar's picture
TerlObar
January 21, 2014 - 3:25pm
I'll have to take a look as well and see how it compares to the vector movement system we published in issue 11 of the Star Frontiersman.  If this is only a page, then it is definintely shorter. Smile
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Blankbeard's picture
Blankbeard
January 21, 2014 - 3:36pm
Thanks for the comment!  I think this is about as simple as vector movement can be (assuming you don't use the speed chart) but it's still more than some people care to deal with.

1) Ok, it's been ages since I've seen the Knight Hawks map or counters (I thought there was a project here that had them but I can't find it.) but I'll make a blank diagram (just a cluster of 7 hexes) and upload it.

I think the easiest way to use the (blank) diagram is to print it out and set it between you and the map. You can then record your speed in each direction and see when you need to resolve them. Poker chips are excellent for keeping track of your speed as you can move them around instead of adding and subtracting.

2) That's an excellent suggestion for an optional rule to simplify using vector movement. I'll include it with a credit for you when I update the document. The only problem I can see is that doing that allows the player to "dodge" dangerous hexes more easily but that's something best handled by the people playing the game.

Re: Stopping.  That's exactly the way it's done. You turn your ship around and fire the engines to stop. That's part of the reason the Lucky Star doesn't stop in the example. It's such a fat ship it takes 3 turns to flip around and another 10 to stop.  My graphic skills are limited but I think I need to illustrate my examples to make sure everything is clear.

Re: Z axis Yeah, adding in the third axis is a bit harder but I think it could be done reasonably with a second Hex diagram. That will probably be an option for update 2 or 3.

Terl: It needs more diagrams which would make it longer.  The actual rules are very short though and they seem to work well in my testing. Please let me know if I've made some horrid error. :)

Abub's picture
Abub
January 21, 2014 - 6:57pm
Makes me wonder what kind of straight braking a ship might be capable of... basically none meaning the only manuvering thruster it has to push itself backwards are low powered enough they are only used when parking at a station?  

Should they get like one point of Deceleration instead of thier full ADF (which would mean no change for ion drives...)


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Abub's picture
Abub
January 21, 2014 - 7:08pm
Here is an idea about "dangeous hexes"

In many Mini style wargames you has a string to determine line of sight where you hold the string at the center of the starting square and take the other end to the center of the ending square to see if it is obstructed.  You could do the same thing to decide if they touched a hazardous square.... Or you could just make a judgment call.  The string method might make it clip the courners of hexes they might not have gone in I suppose.  Maybe ignore corner clipping which makes it a judgement call... but basically say if the string "signifigently passes through" the hex the mine or seeker missle goes off.
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Blankbeard's picture
Blankbeard
January 21, 2014 - 9:35pm
Abub wrote:
Makes me wonder what kind of straight braking a ship might be capable of... basically none meaning the only manuvering thruster it has to push itself backwards are low powered enough they are only used when parking at a station? 


That's a very good question. Real space ships have a system of small thrusters that are used for turning the space craft. Even on the smaller scale I mentioned in the PDF, these thrusters are too weak to produce a full ADF on a reasonable time scale.

The bigger reason for not allowing deceleration is that it ends up devaluing maneuverability. Currently, you might need to turn up to three times before you can change your speed in a particular direction. If you allow deceleration, you never need to turn more than once. It's not hard to avoid a particular hex or a couple together and deceleration makes it easy to avoid large areas.

That's not to say you can't or even shouldn't do it. Just be aware that it can change the tactics that get used.

Blankbeard's picture
Blankbeard
January 23, 2014 - 10:31am
There's an updated hex diagram. If that looks good to people (it's just 7 hexes with instructions) I'll work on the third dimension and revising the article.

Tchklinxa's picture
Tchklinxa
January 25, 2014 - 5:21pm
Abub wrote:
Makes me wonder what kind of straight braking a ship might be capable of... basically none meaning the only manuvering thruster it has to push itself backwards are low powered enough they are only used when parking at a station?  

Should they get like one point of Deceleration instead of thier full ADF (which would mean no change for ion drives...)



That is my take... it is almost like the ships are freight trains, hard to stop. I did kick around the novel idea of engines on the front and rear of a ship as away of speeding up deceration... I am just not sure if that would put to much stress on the hull, but based just on game theory it seems it could work. Now how practicle it would be would be a whole nother issue... 
 "Never fire a laser at a mirror."

Blankbeard's picture
Blankbeard
January 26, 2014 - 7:08pm
For a Star Frontiers style hull with its set number of engine mounts, I'm not sure you could just mount a drive facing forward without spending a lot of money. I'm working on a mass based construction system where your mass and your desired ADF (I guess I should just call it AF) tell you how much thrust and thus how many engines you need. You could say that you wanted to accelerate forward at 4 and reverse at 3. Heck, there's nothing stopping you from buying six sets of engines and making a ship that never turns. Engines are fairly light, and if you're using something like a closed cycle NERVA design (although super advanced) you'd have a central reactor and six heat exchangers.

What this really is highlighting for me is that space ship combat needs weapon arcs. I think you can get by with a cannon arc, like KH already has, and then four or six wedges to be used by batteries.  Four (Front, Rear, Left, Right 90 degree arcs) are probably easier than six (each hex face, 60 degree arcs) but six might be easier to use since it directly overlays the map.

What I'm thinking of is that cannon style weapons come with a cannon arc and cannot be changed (Although if you're buying six sets of engines, you might buy six sets of cannons and build the UPF ship Anywhichwaybutloose). Batteries would come with one arc but additional arcs could be purchased at a cost in both credits and mass. So your weapons list might look like this:

Laser Cannon 3d10 Arc:FC
Railgun 2d10 Arc BB+LB+RB
Laser Battery 1d10 Arc 360
Laser Battery 1d10 Arc FB+RB
Laser Battery 1d10 Arc FB+LB

Obviously, for this to make any sense, that 360 degree laser battery has to be much heavier than the ones with 2 arcs. The obvious tactic for this ship is to approach an enemy, fire its cannon then turn away and keep turning until the enemy is in its rear arc at which point it will have been able to fire every single weapon at it. There might be larger and smaller weapons too that could make several classes of ship viable.

Abub's picture
Abub
January 26, 2014 - 7:19pm
btw i was joking about adding the third dimension.

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Abub's picture
Abub
January 26, 2014 - 7:33pm
I'm planning to ise a sort of facing to dictate which weapons can fire on an enemy but i'm not breaking it into arcs or anything like that.  Or perhaps my arcs are 180 degrees on that side of the ship.

Since I'm using my hit locations I posted about before for hull breaches I'm also going to consider what guns are facing toward the enemy.  I might also let the pilot "Roll" the ship at the cost of MV if they want to lay down fire with both the laser batter and the rocket battery (on thier UPFSF Frigate)


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KRingway's picture
KRingway
January 27, 2014 - 3:26am
Might it be possible to have the engines rotating on pintles in order to control the direction of thrust? That way you could have a form of thrust vectoring. It might also solve the problem with having to completely reverse a ship in order to stop it. The vectoring might be a bit slow in order to go into reverse, but it may be faster than having to turn the whole ship around.

iggy's picture
iggy
January 27, 2014 - 6:39am
Flipping around to slow down is necessary to have gravitational effects on the same surface.  If the engies pivoted around to decelerate then everything would be thrown to the ceiling and the gravitational effect would occur on the ceiling. 
-iggy

jedion357's picture
jedion357
January 27, 2014 - 7:55pm
Plus i would think that class B or C engines would have to have a greatly re-enforced strut to support them and a pivot mechanism.
I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers!

KRingway's picture
KRingway
January 28, 2014 - 11:28am
But it could be an option - as long as everything is stowed, the crew are strapped in, and re-inforced struts aren't technologically impratical. Perhaps this would be necessary as far as combat ships are concerned? I mean, having to turn the ship completely around is going to cause similar problems - it just sounds a tad slower.

Or, alternatively, the engines can pivot to face the opposite way rather than have the whole ship turn around.

Abub's picture
Abub
January 28, 2014 - 3:59pm
Well, I would think the engines are to big to be on pivoting struts but vectored thrust is achieved by the exhaust nozzles turning.  I suppose you could have a nozzle could effectively have an option to curl out and do a 180 with the trust.  Really it wouldn't have to do a 180 to achieve at lease some deceleration just something more than 90 degrees which all of the engines couonter balancing each other.  A full 180 would be most effective unless there is a reason you don't want to blast atomic/ionic exhaust along the ship's sides.  
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Blankbeard's picture
Blankbeard
January 28, 2014 - 6:11pm
I think there are lots of ways a ship could be designed to be able to accelerate and decelerate in the same vector without turning. But doing so, particularly if you have no or simple firing arcs for weapons, really ends up cheapening maneuverability and eliminating a lot of tactics.

There's also the issue that if you can vector/turn thrust to 0 or 180 degrees, you can probably do to 60 and 120 as well. So now you have a ship that can accelerate in any direction without turning and the only good reason to turn is if you want to fire your cannon.

TerlObar's picture
TerlObar
January 28, 2014 - 8:13pm
I posted this somewhere in another thread but I can't remember where.  Back when we were working on the SF combat plugin for the Orbiter space simulator I worked out the gee forces created rotating the various ships.  We were looking at vectored movement and still having forward firing cannons on the ships. 

The question was if it was reasonable to allow you to fire your cannon in any direction regardless of your primary direction of thrust.  The idea was that you'd designate a target for the cannon, stop your engines rotate the ship, fire, rotate back, and turn the engines back on.  We were trying to figure out if you could do that quickly enough that firing once over a 10 minute turn would have little or no impact on your vectors.

And the answer was yes.  You could flip an assault scout around with little or no noticable sideways gee forces in under 10 seconds.  For most of the line ships (frigates, destroyers, lt. cruisers) it could be done in under 30 seconds and even for the battleship is was only 90 seconds.  If you're willing to allow more than 1/20th of a gee of sideways force you could do it even faster.  (I think it was 1/20th although it might have been 1/2, It's been too long and I have to redo the math.)  This all assumes of course that you have large enough maneuvering trusters to get your ship to spin that fast.
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Blankbeard's picture
Blankbeard
January 28, 2014 - 8:41pm
One more reason why I support a one minute turn. :)

I did the same thing for a battleship sized vessel:

Assume 600 m + 25% = 750m

A half turn would be pi * 750 /2 = 1177.5 m

To make a half turn in 1 minute requires 1177/60 = 19.625m centripital velocity.

a= V^2/R = (19.625^2)/375 = 1 m/ss or 1/10 of a gee.

According to The High Frontier tests have shown that about 95% of people can deal with a bit less than 2 rpm with the number sharply dropping off above 2-3 rpm. This is 1/2 an rpm.

The same battleship could turn at 2 rpm with about 1.6 gee which may be a bit much for an RCS system to handle. :)

In a 10 minute turn, any Knight Hawks ship should spin like a ballerina. I was thinking about letting ships by an MR that lets them rotate by 1,2, or 3 hex faces each 1 minute turn. Small ships, up to about assault scout size, could buy a "nimble" designation that essentially lets them fire any weapon in any direction. They can't mount many weapons anyway so it should work out alright.