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This has bugged me for a long time.

How do you measure the distance a unit wheels? Do you use a bendable tape measure to measure out the arc? Or is it enough to measure diagonally, knowing that you've just eked out a few extra smidgens? Is there some kind of handy calculus formula that I can memorize, using the unit frontage and degrees wheeled as variables?

I only ask because though I've collected armies and devoured rulebooks, I've always had a dire shortage of Fantasy opponents where I've lived. I've convinced my girlfriend to play a few games on the kitchen table, which we had fun with, but was pretty useless as far as "learning the rules" goes. Now, however, there are a few fantasy groups peeking their heads up around me, and I'd like to get this small but important detail taken care of so I don't look like a TOTAL dweeb.

Most people measure the diagonal; yes, you lose a small amount, but you can "fudge" that upwards to even it out (so you never gain, or at least rarely will you gain)

You can also have a look at the GF9 templates, fairly certain there is a wheeling template in there.

Our area also typically just measures the diagonal, especially for very short wheels.

If they get particularly long, (like the unit is trying to wheel 90 degrees or more), I'll usually flex the tape measure to make sure I'm not gaining bonus inches.

I never realized this... will have to be a bit more careful about it! I imagine the difference is pretty small in practice most of the time, though.

I have an arc of visibility that has inch markers on the round side, and I normally use that.

Strelka wrote:This has bugged me for a long time.
Is there some kind of handy calculus formula that I can memorize, using the unit frontage and degrees wheeled as variables?

You could use calculus but trigonometry is easier.

Arc Length formula is pretty simple:

(s) = (r) x (Theta)

Where (s) is the arc length, (r) is the radius (width of the block), and (theta) is the change in angle from where you started (in radians).


Granted to do this you'd need a protractor or something to measure the angle change and then convert degrees into radians which is pretty simple as well.




Moral of the story: Just get the GF9 template or fudge the diagonal. Opponents will get annoyed if you sit there measure the angle, and do the math each time.

Thanks for the replies. I figured most people would probably go the diagonal route as it IS much much simpler. But I've come across my fair share of grognards and rules lawyers over the years, and I didn't want to walk into an established group and start cutting corners.

I always thought it was strange that the BRB didn't go into specifics about that one thing.

And thank you for the formula, Nungunz. I may not use it for real, but it helps to have a few handy numbers stuck in the back of the head (small bases and a frontage of 8 wheeling 30 degrees? Why, I'll have an extra inch and a half left to set up the charge!) is always helpful. My buddy Pythagoras and I really were quite a dynamic duo back in the days of guess range weapons.

Strelka wrote:I always thought it was strange that the BRB didn't go into specifics about that one thing.

Why what does it go in specific detail on?
GW rules jokes aside, most people consider it more practical to use the diagonal method, it is all fair in the end if both sides do it that way anyhow.

Strelka wrote:
And thank you for the formula, Nungunz. I may not use it for real, but it helps to have a few handy numbers stuck in the back of the head (small bases and a frontage of 8 wheeling 30 degrees? Why, I'll have an extra inch and a half left to set up the charge!) is always helpful. My buddy Pythagoras and I really were quite a dynamic duo back in the days of guess range weapons.

Okay, because I'm sick at home, bored as hell, and just finished some Propulsion homework I got curious.

Using arc length method:

8 x 20mm = 160mm = 6.2992 inches = (r)
30 degrees = pi / 6 radians = (theta)

(r) x (theta) = 3.29825 inches


Using the diagonal method:

We know angle A = 30 degrees and since the triangle created by the point of rotation, start point, and end point is an isosceles triangle we know angle B = angle C = 75 degrees.

By Law of sines we get: d / sin (A) = (r) / sin (B) = (r) / sin (C)

so (d) = sin (A) x (r) / sin (B) = 3.26071



So really you'd only be saving around .04 inches. Really doesn't make a huge difference.


God I'm bored.......

LOL but now you KNOW. And in the (admittedly unlikely) event that it should crop up in a friendly or a tournament, you will know offhand that a diagonal measurement shaves off 0.04 inches per 30 degrees. You'll be the smartest guy in the room!

On the other hand, if I use my arc of vision template to measure my wheel, I do run into problems.
My 6 wide block of chaos warriors uses that arc of vision thingy. The radius of that arc is only 4", with the center 1" cut away.
My 6" wide block is now turning on a 4" wide circle.
A 60 degree wheel (not that uncommon) costs ~4.2" instead of 6.2"
I just saved 2".
The wider the unit gets, the more inaccurate that wheel becomes.
Please, use the diagonal, and get the small error.
As for flexible tape measures; I believe that's a bad idea too. Just pick up a pen and try and draw a circle. It is extremely difficult to free hand a perfect circle. That's the same sort of skill you need to flex measure an arc.

-Matt

IDK Nungunz the radious in that formula would change according to unit formation (hordes having a considerably bigger one than buses) and thus making the result vary form 0.4. I would say the best way to determine all the outcomes is by using integral mathematics which would result in a (hopefully simple) formula that can be used in accordance to the situation.

HoverBoy wrote:IDK Nungunz the radious in that formula would change according to unit formation (hordes having a considerably bigger one than buses) and thus making the result vary form 0.4. I would say the best way to determine all the outcomes is by using integral mathematics which would result in a (hopefully simple) formula that can be used in accordance to the situation.

Technically that formula is the solution to the integral. And yes of course the radius would change depending on the unit

Ahh so (r) is where the unit frontage goes, apparently i'm not good enough to utilise both my integrating and english skills at the same time.

As long as no-one is ever taking advantage of the system through using silly frontages no harm no foul. It all shakes out in the end because both players get the same advantage/disadvantage.