Scale Speed

[conch]

Can anyone explain the formula to determine scale speed. The formula I have came from the book Model Submarine Technology, but it doesn't have an explanation of the values in the formula. The formula is on page 24 of the book. I am not sure how to put the formula in here as it is shown but written out it is:

Vmod equals Vorg divided by the square root of MaBstab (the "B" is not a normal B).

I am pretty sure Vmod is the model speed and Vorg is the speed of the full size boat, but after that I am lost.[/code]

[JWLaRue]

Ahh, yes. The definition of

Ahh, yes. The definition of scale speed is always an interesting discussion since there are different ways to 'define' it. Some view scale speed as a linear function, some view it as the speed that causes the ship to create a waveform that is visually the same as the full-size object, and there are others.

For this variant.....

The word in German is der Maßstab and basically means 'scale'. That formula is looking for the square root of the scale.

-Jeff

[conch]

Thanks, I was looking for

Thanks, I was looking for the "scale" that would create the realistic wave form. Now, as for the scale of the model it is 1/96 or 1/8", which scale do I use?

[conch]

I tried both 1/96 and

I tried both 1/96 and 1/8 and I must be doing something wrong or the answer is in a different unit than the org speed, i came up with 84.86@1/8 and 294.4@1/96. I am trying to figure the speed for a 1/96 L.A Class assuming a submerged speed of 30 knots.

[redboat219]

Scale speed= speed (actual scale)

Scale speed= speed (actual scale) divided by square root of the models
scale.
In the case of the 1/144 Trumpeter seawolf,
40 knots Speed of actual sub divided by 12 (square root of 144) equals 3.3 knots

[conch]

Got it thanks

Got it thanks

[Guest]

I think if you walked

I think if you walked beside your sub at about a medium pace of 3mph(1mile in 20 min.), that would be the scale speed. Rounding off the scale 96 to 100, you would divide the speed of the full size sub by 10.

[conch]

Yeah by my figures I

Yeah by my figures I came up with a touch over 3knots, thanks.

[hakkikt]

The question is of course

The question is of course how we define "realistic".

The formula was originally searched to help making the results of watertank tests with models applicable to real-size ships. In this case, "realistic" means: what speed will best replicate the behaviour of the original in the hydrodynamic sense? Arguments like "this boat is moving much too fast" in the sense that e.g. it travels once through its own length much faster than the original, will be secondary. In a strictly looks-oriented modeling perspective, the speed of a 1/96 model must be 1/96 the original speed. That's of course boring.

I guess the formula is a nice point for making our boats go faster than scale would allow them to go (dont we all like them to go fast? ), and waveform WILL be important for e.g. a Type VII on the surface, or even for a periscope sticking out.

[raalst]

Hakkikt, you email address as

Hakkikt, you email address as mentioned in your profile is probably old.
please consider updating it. someone has sent a PM, and the mail alerting you to that fact has not reached you. I got a delivery failure notification instead.