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Subject: Ship Movement Example rss

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Matt Watkins
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In the thread for my Tabletop Simulator mod,
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asked for an explanation of ship movement using the new fuel strip. I thought I'd post it here, with screenshots from the mod. Please correct me if I've made mistakes; I'm a newbie too.

Here is the rocket we'll be using for our journey.


Step 1 - Dry mass: The total dry mass of the rocket can be determined by adding up the mass numbers in the upper right-hand corner of the cards. Our rocket has a dry mass of 4. (2 for the reactor + 1 for the thruster + 1 for the crew.) We mark the dry mass on the fuel strip using a blue disc on space 4. We'll use the Ablative Plate as the thruster for this whole example (instead of the crew card.) Its triangle is blue, meaning it uses water for fuel, so we use the blue rocket shaped fuel figure to mark our wet mass. Since we haven't fueled the rocket yet, our wet mass is the same is our dry mass. Place the fuel figure on top of the blue disc. It should now look like this.


Step 2 - Fuel it up: For this example, we'll assume we have 4 water tanks in our depot and load them all onto our rocket as fuel. For every tank of fuel loaded, we remove a blue disc from our depot and return it to the supply. Then move the fuel figure one space forward along the red dotted lines. For four tanks, this means we move our fuel figure from space 4 to space 8, like so.


Step 3 - Thrust
: Notice in the above figure that the fuel figure is in the Scout region of the fuel strip, with a thrust modifier of +0. Our thruster's base thrust is 2 (the left number in the thruster triangle), and since we're playing the ESA, we can use our powersat to boost the thrust by 1. Our reactor gives us solar thrust as well, but in the Earth zone that thrust modifier is 0. So our total thrust is base+ship class+powersat+solar=2+0+1+0=3. You can see in the above figure that we've placed a blue disc on the number 3 on the net thrust track. This means we can pass through 3 burns when we travel.

Step 4 - Move: For the example, we'll start in LEO and move our rocket along the light blue track (toward Comet Encke). Our first move is from LEO to HEO, where we have to burn fuel to enter our first burn. Our thruster has a fuel efficiency of 2 (the right number in the thruster triangle), so to burn fuel we move our fuel figure back two spaces following the black line. (Red line when adding fuel. Black line when burning fuel.) And here is the result, with the fuel figure on number 7.


Next we'll move from HEO to GEO and enter our second burn. We have to roll for the radiation hazard between the two. Assuming our rocket survives, we have to expend fuel again to enter the burn, moving our fuel figure back two spaces along the black line to the number 6.


Next we'll move from GEO to the next burn along the light blue track, changing direction for free at the Sol-Earth L2. Then we'll expend fuel again to enter the burn, moving our fuel figure back 2 spaces to 5 1/3.


And finally, we're going to perform a daring aerobrake maneuver around Mars and attempt to land on Phobos. We've already passed through the three burns our net thrust permits, but the fly-by spot near Mars gives us a free burn. Then we have to roll for the aerobrake hazard, use our free burn to pass through the burn between Phobos and Deimos, and land our rocket on Phobos.


Note that I don't think there's really a good reason to go to Phobos with this rocket since the ISRU rating of the crew card is too high to refuel here, but it's a good example of how to use the fuel strip. Hope this helps.

Also note that I believe if we had used the afterburner when determining our net thrust, we could have landed on Mars. Figure out that trip for your homework.
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Canada
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Fantastic, thank you so much !

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Kyrill Melai
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Once I could recite whole episodes of Dexter's Laboratory.
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Great tutorial for players completely new to the fuel strip or HF in general.

One thing though. Your wording suggest you spend fuel to continue moving after entering a burn. In reality you spend fuel upon entering the burn. Is it any trouble to change the wording a little to reflect this?
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Matt Watkins
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NoDDs wrote:
Great tutorial for players completely new to the fuel strip or HF in general.

One thing though. Your wording suggest you spend fuel to continue moving after entering a burn. In reality you spend fuel upon entering the burn. Is it any trouble to change the wording a little to reflect this?


Ah yes, embarrassing error. I think I can finesse it to work without changing the pictures.

EDIT: Fixed, I think. Thanks!
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Kristabelle Du Bast
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Thank you for taking the time to make this tutorial. Your style is wonderfully clear and precise. I much prefer this format to videos where details can easily be glossed over leaving you confused and frustrated.
A nice taster for a game that I fear is still some months away.
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Charlie Mote
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Great example of movement. Agree that images are better than video.

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Canada
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I don't see the images any more. I only see a small icon for each of them...
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Matt Watkins
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plong999 wrote:
I don't see the images any more. I only see a small icon for each of them...


Yeah, I see that too, but I'm not sure why. The links all work individually, but don't show up embedded in the post for some reason. I'll investigate.

EDIT: It seems to be a site-wide problem on BGG. It's discussed here:
https://boardgamegeek.com/thread/1507324/external-images-sho...

I'm gonna wait for a couple days to see if it gets resolved, then try to either find other image hosting than imgur, or recreate the whole example as a pdf that I upload to files.
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Canada
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It is back to normal now. Thanks Matt.
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Will H.
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Thank you! Your post was much easier to read and understand than the new rule books (which is very disappointing).

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Steve Carey
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Matt, thanks so much for the effort to put this together.

Just a quick note, since fuel ended at 5 1/3 it would adjust left (down) to 5 at the end of the turn.

More illustrated examples like this would be cool. whistle
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K H
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Steve Carey wrote:

Just a quick note, since fuel ended at 5 1/3 it would adjust left (down) to 5 at the end of the turn.


I don't believe so. You don't round fuel steps that represent fractional amounts of a fuel tanks to amounts that represents full fuel tanks. You round fractional amounts of a fuel step.

Say you had a thruster with an efficiency of 1/2 and started at wet mass six. If you did a single burn, you would use half a step of fuel. When you finish the burn, you would then round down to the next fuel step which would leave you with a wet mass of 5 2/3.

You can also think of it as rounding all your fuel usage up to a whole number of fuel steps used after you finish moving (so one burn at 1/2 fuel usage rounds to a full fuel step).
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Steve Carey
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That's a tricky one, but I see now what you're saying now (thanks for the clarification, I hadn't considered 1/2 fuel steps when reading the rule).

 
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Gar Per
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ShieldOfMeat wrote:
Steve Carey wrote:

Just a quick note, since fuel ended at 5 1/3 it would adjust left (down) to 5 at the end of the turn.


I don't believe so. You don't round fuel steps that represent fractional amounts of a fuel tanks to amounts that represents full fuel tanks. You round fractional amounts of a fuel step.

Say you had a thruster with an efficiency of 1/2 and started at wet mass six. If you did a single burn, you would use half a step of fuel. When you finish the burn, you would then round down to the next fuel step which would leave you with a wet mass of 5 2/3.

You can also think of it as rounding all your fuel usage up to a whole number of fuel steps used after you finish moving (so one burn at 1/2 fuel usage rounds to a full fuel step).


So a fractional efficiency is, for all intents and purposes, an efficiency of 1, except when executing multiple burns (such as at a Hohmann)?
 
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K H
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nate_lockhart wrote:

So a fractional efficiency is, for all intents and purposes, an efficiency of 1, except when executing multiple burns (such as at a Hohmann)?


You round at the end of the move. So, if you do 5 burns in the course of a move with an engine of efficiency of 1/2 you will pay 3 steps of fuel (2.5 steps which round to 3 at the end of the move).

Edit: Clarity.
 
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Alex Mauer
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ShieldOfMeat wrote:
You round down at the end of the move.


"Round up", surely?
 
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K H
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Hawke wrote:
ShieldOfMeat wrote:
You round down at the end of the move.


"Round up", surely?


Yes? I get confused at which terminology to use. You round up the number of fuel steps used but round down how many fuel steps you have.
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