[WIP] Fleet Boat Engine Hour Mod

[Rosencrantz]

Hello!


I managed to balance SH4 Gato/Balao/Tench -class engines so that each of the standard bells represents now engines on the line properly. Usually there has been mismatches in triangle "engines on the line/speed/range + hours." (For example endurance in hours dropping to 1/3 by speeding up from 2/3 speed to standard speed, even if that action should only put one more engine on the line.) After hours of research and playing with S3D and Notepad, I finally got these results:


1/3 speed or 1 engine on the line = 1800 hours with max fuel
2/3 speed or 2 engines on the line = 900 hrs with max fuel
STD or 3 engines on the line = 600 hrs
FULL or four engines on the line = 450/260 hrs depending on speed
FLANK = approximately 190 hrs with max fuel.

Anyone interested in?


-RC-

[TorpX]

I certainly am.
Better physics and models are always worthwhile.

Does this have any effect/ application for S-boats?

[virtualpender]

Finally! This is definitely needed. Will it work with TMO?

[AVGWarhawk]

[Runnybabbit]

Brilliant! Definitely interested in this.. thanks!

[Rosencrantz]

Hi!

I don't see any reason why Fleet Boat Engine Hour Mod could not be used together with any other mod or stock. What becomes to S-class I can't say anything yet, as I lack exact real life data about enignes fitted, their performance, and especially standard operating procedures.

As I'm still in the middle of the building process, I can't say much more. However, here is few quotes from real Navy documents, and conclusions I have made:


The Fleet Type Submarine Main Propulsion Diesel Manual, Chapter 9 Engine Performance and Operations, page 182: "The economical speed for most Navy type diesel engines is found to be from 70 percent to 80 percent of the rated load or output. Thus, we speak of running the engines at an 80-90 combination which will give the engine itself much cleaner and in better operating condition. The 80-90 means we are running the engine with 80 percent of rated load at 90 percent of rated speed."

My conclusions: Because a single diesel engine running at 80 percent of it's rated speed used probably about 6 - 7 times of fuel compared to engine running at 50 percent of it's rated speed, I'm positive that fuel consumption was not Navy's problem number one before, during or after the war. It was prolonged periods in engine overhaul what they tried to avoid as much as possible. This is the real reason why standard Navy procedure was to put less engines on the line running at higher speed to gain requierd speed. That 80-90 combination was not just a theory, we can see here:

USS Wahoo, Third War patrol, Report of, Jan 16, 1943: "2306L Completed runs. Set course for area at two engine speed (80-90). Still in company with our escort."

Conclusions: When Wahoo departed Pearl for the third war patrol, they put two engines on the line running at 80-90 combination. As Wahoo had 4 x Fairbanks-Morse Model 38D8-1/3 9-cylinder engines running four generators with emergency output of 1120 kw at 720 rated speed, 900 kw at 650 rpm, and with overspeed trip setting of 800 rpm, this means they were using 2 x 900 kw to run the boat when leaving Pearl.

But what was the actual speed they were running at? Because there is no clear connection to propeller rpm and actual speed in ships (compare to cars, for example) because of conditions are always different (wind, sea state, cargo on board, ship's material conditions and so on...) we can only try and make good estimations. If someone is interested in, I can write more. Now I have to get on with my every day job... sorry.


-RC-