[SF]Speed Discussion

I wanted to discuss the speed issue just a little if we may.

After the build session at Tuggies we think the displacement may be a little hard to get the battleship up to 28 sec. It may do it, may not... I have one close to being hull ready for testing.

What I think we should do is this. I will get the BB up and going for a test run. Since one of the objects in the [SF] is to make these as cheap on the wallet as we can, I will be testing it with a standard 550 can, 6vlt system. This way the speed can be reached by any captain no mater what type of motor they have, brushed or brushless.
We can then take a look at the top speed I can get the BB up to. If it hits => 28 sec, then all our speeds are good, and we can adjust the speeds down if needed by drag props, end points, ect.. If the BB can not hit 28 sec, then we will go off what ever speed it can get to. Using the theory that the lighter, sleeker, AC and PC can go faster due to the shape and weight difference. So for example, say the BB only gets to 30 sec. We can then adjust the AC top speed to 28, and the PC to 26.
I think this would be better than to add another prop to the ship.
I would also suggest not limiting the prop to just one vender. I would just limit the diameter of the prop and keep everybody at the same rudder size. I think we had a 1.75 fit the AC at the build session. I will check tonight.

I will also start the thread for the BB I am building... the tumblehome is looking great! but thats for anther thread...

 

Just remember, these are fairly large ships. Slow them down too much and turning will be very poor.

 

The target speed for the Steampunks should be between 27 and say 34 seconds. The Convoy ships are rated at 34 seconds. Having a Steampunk that does 23 second (WWII) cruiser speed would be silly. Predreds were not built to sink the IJN Mushashi or an HMS Iron Duke (However fun that might be).
Manuel Mejia, Jr.

 

I never mentioned that they should go at 23 seconds, I just stated that low speed brings on sluggish turning especially with big ships.
The target speed you listed sounds reasonable. Maybe adjust the top end to 26 seconds and have PC's at 26, and ACR and BB's at 28 and convoys at 34.

 

I would like to keep them at 28 sec... thats the goal anyway.

Have you seen the hull/rudder comparison? LOL,, turning is going to be fun as it is....

 

We can only put bigger rudders on them. Can't wait to see some test results.
ST

 

I just did a quick,very rough estimate of dynamic similitude speed for 18 knots in 1/96 scale, which should work out to about 29 seconds per 100ft. Someone may want to double check my math on that.

 

Hmm....quick & dirty:
1:96 means 1"=8'
28 sec/100' means "full scale" 28sec/9600'. Flip and you have 342.85 ft/sec or 203 knots... wait a sec.......:blush:

Um.... how does time scale, again?

Let's try it the other way. RL 18 knts is 30 f/sec.
1:96 scale that's 3.75 in/sec. To cover 100' would take 26.667 seconds. Pretty darn close

 

DSS uses the square root of the scale. 144 is nice because the root is 12,an easy number to work with. 96 is a bit tougher, the root is approximately 9.8.
So, convert 18 knots to scale knots:
18 * (1/9.8) = 1.837 knots
convert knots to feet per second (using a unit converter program):
1.837 knots = 3.1 feet per second
convert feet per second to seconds per 100 feet:
(1 / 3.1) * 100 = 32 seconds per 100 feet.

So 18 knots is about 32 seconds... I may have mistyped something last night... When I get back from leave, I'll dig up the spread sheet I use to calculate speed tables and such.

 

For follow up: Has anyone actually floated a SF hull yet? I'm curious as to the weight needed for the AC to displace down to designed waterline. And once it's wet, I really want to know how well it moves & turns w/ it's plastic prop / 1 rudder combo.

 

From what I have been gathering, the Steampunk group has been working on boats for the upcoming Labor Day regatta. I seem to be the closest to launching since I have most of the parts assembled except sheeting the hull. I am waiting for some additional parts that I can install to get BB-000 up to operating weight. Once I get the radio, etc installed, then I can do sea trials.
MMJR