Fuel: Discuss these two choices

[Sailor Steve]

Originally Posted by orangenee

Not really realistic for me, if they modelled the world correctly then I'd probably go for realistic but they didn't.

An excellent point. I voted for absolute realism, but you're right - their world isn't round.

[AVGWarhawk]

This is were I'm lost on the realism concerning fuel. From what I understand the 12000 nm was running at ahead standard or around 14-15 kts. We are stop gapped to 10.8 kts to make the patrol area and make it home. Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

[Ducimus]

Originally Posted by AVGWarhawk

Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

Offhand, i don't think it can. Fuel or battery consumption seems to be a result of RPM"s. The more RPMs, the faster the energy loss. The only thing i can think of, is to maybe change the engines power. Im not sure, but i think engine power might be relating to how much energy it draws in order to run. Reduce the engine power, maybe you'll reduce the fuel needed to run it. Sounds funky, but remember theres still a "top speed" variable to play with. In theory if you lower its power, and increase its top speed you've made it more efficient.

[chopped50ford]

Originally Posted by Misfit138

I'm a realism junkie so...

Realistic:12,000 NM @ 10 kts ( loosely translates into "ahead 2/3rds")

Just wished that with this option there would be also an option to call a tug boat if on friendly territory

Im for these idea's.

Is a Tugboat possible?

[Redwine]

Originally Posted by Ducimus

Offhand, i don't think it can. Fuel or battery consumption seems to be a result of RPM"s. The more RPMs, the faster the energy loss. The only thing i can think of, is to maybe change the engines power. Im not sure, but i think engine power might be relating to how much energy it draws in order to run. Reduce the engine power, maybe you'll reduce the fuel needed to run it. Sounds funky, but remember theres still a "top speed" variable to play with. In theory if you lower its power, and increase its top speed you've made it more efficient.

Mmh... may be i am wrong Ducimus... but i think so it is posible.

The maximun range speed is just that adjusted on the sub .sim file.

The fuel compsumption seems to be not related to the engine RPM, because, if into the files is adjusted in example 12000 miles at 10knt.... if you sail at 11knt, your range become reduced.... but... if you sail at 8knt, at lower RPM, the range is reduced too, and fuel compsumption is increased.

You can check it using the Shift+G function, "Max Range at this present speed".

May be i am wrong... but if we can an economy speed of 15knt in example, the only thing we need is to adjust it into the sub file.... as the speed for the max range.

But then, when you will sail at 10knt you will spend more fuel than at 15 knt.

I am not sure if the team made it intentionally, but it is real... all alternative motors have an efficience curve, it is at top of the torque curve, if you use the engine at max torque vale, you save fuel, if you use it over or under you losse fuel.

In example, my car has a max torque at 2600 rpm, if i use it at 4500rpm, or 2000rpm i lose fuel.

The max range is 2600rpm wich is 90km/h at 5th gear into the gear box.

if i run on 5th, at 40km/h or 140km/h i expend more fuel than at 90km/h.

[AVGWarhawk]

OK Redwine, you are great at file alteration and modding. Do you think this can be done?

[Ducimus]

I think he just said it can?

Im not saying it can't be done, im just saying im skeptical if it will work out the way we'd want it to.

[JSF]

Originally Posted by AVGWarhawk

This is were I'm lost on the realism concerning fuel. From what I understand the 12000 nm was running at ahead standard or around 14-15 kts. We are stop gapped to 10.8 kts to make the patrol area and make it home. Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

Excellent point! Everything I have ever read concerning cross Pacific transits to patrol areas agrees with this speed factor.

[Sailor Steve]

Before you run with that ball you might actually want to look at some sources:
http://www.valoratsea.com/gato.htm
http://www.valoratsea.com/Sclass1.htm
http://www.valoratsea.com/Salmon1.htm

I had a look in Conway's, and it's the same: all ranges are given at ten knots. U.S. surface ships are given at 15 knots, but I suspect that 10 was still more economical; 15 just allowed faster transit times, and they could refuel at sea.

[Redwine]

Originally Posted by JSF

Excellent point! Everything I have ever read concerning cross Pacific transits to patrol areas agrees with this speed factor.

Originally Posted by AVGWarhawk

OK Redwine, you are great at file alteration and modding.

Not true ! but many thanks... i am only a "persistent" dummy... but i am capable to stay 4 months tweaking up to reach what i want !

Originally Posted by AVGWarhawk

Do you think this can be done?

Originally Posted by Ducimus

I think he just said it can?

Im not saying it can't be done, im just saying im skeptical if it will work out the way we'd want it to.

Yes... i think so it can be done.

But i am not sure... it is my supouse.

Let me to made a small pack of files to upload...

But as Sailor Steve wrote... will be not real, the fuel economy speed was 10knt not 15knt.

Originally Posted by Sailor Steve

Before you run with that ball you might actually want to look at some sources:
http://www.valoratsea.com/gato.htm
http://www.valoratsea.com/Sclass1.htm
http://www.valoratsea.com/Salmon1.htm

I had a look in Conway's, and it's the same: all ranges are given at ten knots. U.S. surface ships are given at 15 knots, but I suspect that 10 was still more economical; 15 just allowed faster transit times, and they could refuel at sea.

[Ducimus]

You know, in light of this thread :
http://www.subsim.com/radioroom/showthread.php?t=120398

I am seriously contemplating bringing fuel in TM back to stock levels. . Stock is 15,000 NM @ 10 kts. THe historical spec, is around 12,000 NM @ 10 kts, thats 3,000 NM more range in stock. Now ive always wondered if the historical spec is taking into account of fuel being stored in ballast tanks.

To play "Make beleive" for a minute here. Lets assume that 12,000 NM @ 10 kts is NOT taking account of fuel in ballast. That means that, theortically, ubi's 3,000NM over the spec, IS. That 1,500 NM per ballast tank (as i beleive two tanks were used for this purpose). So by that logic you could, go back to stock fuel, and feel ok about it.

edit: yeah slightly off topic i know, just thinking aloud.

[Sailor Steve]

Given the point made by orangenee about the earth modelling (there is no great circle route in the game) you're probably right about the extended stock range.

[Redwine]

Originally Posted by Ducimus

You know, in light of this thread :
http://www.subsim.com/radioroom/showthread.php?t=120398

I am seriously contemplating bringing fuel in TM back to stock levels. . Stock is 15,000 NM @ 10 kts. THe historical spec, is around 12,000 NM @ 10 kts, thats 3,000 NM more range in stock. Now ive always wondered if the historical spec is taking into account of fuel being stored in ballast tanks.

To play "Make beleive" for a minute here. Lets assume that 12,000 NM @ 10 kts is NOT taking account of fuel in ballast. That means that, theortically, ubi's 3,000NM over the spec, IS. That 1,500 NM per ballast tank (as i beleive two tanks were used for this purpose). So by that logic you could, go back to stock fuel, and feel ok about it.

edit: yeah slightly off topic i know, just thinking aloud.

Not sure of that Ducimus... i suspect the game use statute miles, (+- 1.65km) instead nautical miles.

Then when i tweaked my files i let this value at stock value 15000, really... if i am right, it must be +- 13600...

12000nm are about 13600 stm.



Here a little pack of tweaked files containing the sub.sim files with the max range speed adjusted to 15knt....

If some body want to check if the economy speed is moved or not now up to 15knt here you have.


Download here :

http://files.filefront.com/Subssim+f.../fileinfo.html

[Ducimus]

... i suspect the game use statute miles, (+- 1.65km) instead nautical miles.

I was wondering that myself until i tried it ingame. Orginally i modded diesals to be 12,000 @ 10 nm. This is almost the exact range the NA would report if i was at a speed of 10 kts. In TM, he will report higher then that, because i "faked" the fuel range and changed it to 12,000 @ 10.95 kts. It in effects give around 1000 to 2000 more NM's out of the NA's report. edit: now having said all that, i still could be wrong, NA reports always were a little "fuzzy" to say the least.

[Ducimus]

Sorry guys, im still stuck on fuel. I swear i have a fetish with it.

I suppose its about time i look in a technical manual. I hate reading tech manuals. Ever see a tech manual from the USAF? its so cut and dry, you want to fall asleep after 5 mins of reading. Sadly a USN manual from 1940's is more easily understood then a current AFTM.

http://www.maritime.org/fleetsub/diesel/chap5.htm#5A
http://www.maritime.org/fleetsub/die...ut/fig5-01.htm

Fuel oil tanks.
They vary in size, but normally have capacities of from 10,000 to 20,000 gallons each. Most modern submarines have four of these tanks. In a typical installation (Figure 5-1) they are numbered No. 1, No. 2, No. 6, and No. 7.

Fuel ballast tanks.
Most fleet type submarines have three fuel ballast tanks varying in capacity from about 19,000 to 25,000 gallons. On a typical installation (Figure 5-1), the fuel ballast tanks are numbered No. 3, No. 4, and No. 5.

So lets assume a the following scnearios on on fuel oil tanks, and fuel ballast tanks

Worst case:
Fuel oil tanks @ 15,000 gall. each X 4 = 60,000 gallons.
Fuel ballast tanks @ 19,000 gall each X 3 = 57,000 gallons

97,000 total gallons.

Middle ground:
Fuel oil tanks @ 19,000 gall. each X 4 = 40,000 gallons.
Fuel ballast tanks @ 22,000 gall each X 3 = 66,000 gallons

106,000 total gallons.

Best case:
Fuel oil tanks @ 20,000 gall. each X 4 = 80,000 gallons.
Fuel ballast tanks @ 25,000 gall each X 3 = 75,000 gallons

155,000 total gallons.

Now, IF an average fleet boat does 12,000 NM with 96,000 gallons of fuel oil. ( http://www.navsource.org/archives/08/08206.htm ) That means its burning on the average 8 gallons of fuel per 1,000 NM.

So then

Worst case
97,000 total gallons. / 8 = 12,125

Middle ground
106,000 total gallons. / 8 = 13,250

Best case
155,000 total gallons. / 8 = 19,375