R/C Naval Combat

Battlestations uses the speed chart from the North Texas Battle Group. I am trying to extend the list a little bit. Can some one give me the formula used to calculate it?

Thanks,
James

I can help with that. The Big Gun Speed Chart is based on something called Dynamic Similitude Speed.

DSS = speed * SQRT(scale)

an example, 25 knots in 1/144 DSS:

25 kts * SQRT(1/144) = 25 kts * 1/12 = 2.0833 kts = 3.516 ft/s = 28.4 seconds per 100 feet

The big gun speed chart is actually 63.1% of 1/144 scale DSS. The same speed would be 50.8% of 1/96 scale DSS.

Big Gun speed = historical speed * 0.631 * SQRT(1/144)

Battlestations speed = historical speed * 0.508 * SQRT(1/96)

Note that Big Gun speed and Battlestations speed will be the same, because they use the same speed chart, so you can use either calculation to extend the chart. Another interesting point is that 1/10 KPH is ALMOST exactly 1 knot on the speed chart. That is, 2.2 KPH is very close to 22 knots and 3.5 KPH is very close to 35 knots, and so on. It turns out that the precision of the radar gun used for speed checks in the WWCC is less than the difference between the KPH and the speed chart, so it could be used with no noticeable difference in performance.

I hope that answers the question.

Yes, it does quite throughly. Thanks.

j.

Now it begs the question as to whether or not I should recalculate the Battlestations speed chart to make it based on a scale speed. We are currently using a 1/144 scale chart for 1/96 scale ships.

As it would be a ton of work to change all the ship lists I think I shall leave things as they are.

Double checking...this is the knot that is 1.687810 feet per second?

DSS is used by ship and airplane designers when testing scale models. Because water and air don't scale down very well, DSS is the best approximation to "scale speed" possible. In other words, DSS is scale speed.

The big gun chart is actually a fraction of scale speed. 25 knots on the big gun chart corresponds to 63.1% of 25 knots in 1/144 DSS, and also corresponds to 50.8% of 25 knots in 1/72 DSS. Full DSS in 1/96 will be much closer to fast gun speeds. A rough estimate indicates that 25 knots in 1/96 DSS would be around 23 seconds. Can you imagine the power that will take to get a battleship up to speed?

Yes, 1 knots is 1.68710 ft/s.

sounds like fun

quote:

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Originally posted by Gascan

Can you imagine the power that will take to get a battleship up to speed?

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RAR! UGH! MANLY POWER!

what is the typical scale speed of a fletcher class destroyer?

The Fletcher is listed in Conways at 38 knots. That is equivalent to 3.8 kph and 2.36 mph

quote:

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quote:

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Can you imagine the power that will take to get a battleship up to speed?

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RAR! UGH! MANLY POWER!

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hehe, I still find this amusing, Tugboat.

reguarding how much power it would take to get ships up to speed, if people in Battlestations want to use the formula to make its own speed charts it could eliminate the minimum speed and it doesn't really take too much to get even the biggest up to speed. found this out when my Yammer was hydroplaning 8) (I'll get some pics of this soon)

For anyone misreading KPH used here is km/h not knots/hr (which is kind of redundant). So, to reiterate 2.1 km/h (kilometers/hr) = 21 knots.

Haven't done the math, but I am thinking that 0.1 mph per knot would be getting pretty close to appropriate for 1/96. So 2.3mph would be 23 knots. Easy to caldulate and measure. But, of course, if you want to stay with the speeds you are used to, 0.1 km/h per know makes it really easy to extend the chart both directions.

Cheers,