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Fuel consumption Bismarck

Posted: Tue Mar 22, 2011 8:29 pm
by Thorsten Wahl
just a question
KBismarck states following
Fuel: 8,294 metric tons

Range:
9,280 nautical miles at 16 knots
8,900 nautical miles at 17 knots
8,525 nautical miles at 19 knots
6,640 nautical miles at 24 knots
4,500 nautical miles at 28 knots

what is the source of this data
is it known at wich rpm / horse power output wich speed occurs?

for instance bismarckclass give these figures
http://www.bismarck-class.dk/technicall ... inery.html

138,000 PS required for 29 knots - 265 rpm - fuel consumption 0.325 kg/PS h --> 44.85 metric tons per hour
so endurance at 29 knots should be ~185 hours
=5,385 nautical miles if I neglect weight reduction

all other data did not contain speed
if I take
128 rpm for 16 knots(estimated) - fuel consumption is 15,000 PS x 0.5kg/PSh ---->7.5 metric tons per hour
endurance should be 1,105 hours
=17,694 nautical miles

If i compare rpm and speed for US battleships my estimate seems correct
http://www.ibiblio.org/hyperwar/USN/ref ... el-BB.html

Whats wrong with my calculation?

Re: Fuel consumption Bismarck

Posted: Tue Mar 22, 2011 9:25 pm
by dunmunro
Theoretical fuel consumption figures will not match actual consumption for various reasons:

The need to keep more boilers lit as a precaution than are needed for best economy

degradation of machinery from prolonged use with insufficient maintenance.

bottom fouling and increased drag

the need to keep oil tanks in the torpedo defence system topped up with seawater, and the consequent loss of some oil due to fouling and a reduction in combustion efficiency due to higher moisture content in the fuel oil.

The need to factor in the effects of bad weather and/or sea state on projected range

increased displacement of the ship requiring increased SHP to maintain a given speed.

Re: Fuel consumption Bismarck

Posted: Thu May 26, 2011 6:21 am
by Keith Enge
Theoretical endurance also often doesn't take into account power used to drive auxiliaries or to generate electricity to run other equipment. German ships were known for spending an unusual amount of their horsepower powering auxiliaries; I have seen data which says that it was up to a third of the total.

Re: Fuel consumption Bismarck

Posted: Wed Dec 14, 2011 8:46 pm
by Thorsten Wahl
Fuel consumption
official figure from Gruppe West
Treibstoffverbrauch.jpg
Treibstoffverbrauch.jpg (35.85 KiB) Viewed 13644 times
10.400 Seemeilen at 17 Knoten
8.600 Seemeilen at 21 Knoten
5.350 Seemeilen at 28 Knoten
Basis Fuel 7.700 m³

Re: Fuel consumption Bismarck

Posted: Thu Dec 15, 2011 2:11 am
by dunmunro
Thorsten Wahl wrote:Fuel consumption
official figure from Gruppe West
Treibstoffverbrauch.jpg
10.400 Seemeilen at 17 Knoten
8.600 Seemeilen at 21 Knoten
5.350 Seemeilen at 28 Knoten
Basis Fuel 7.700 m³
I believe that it states that May 18 to 22 = 300 tonnes/day for 3 days (72 hrs)

may 22 to 23 = 450 tonnes/day (24 hrs) at 21 knots

May 23 to 24 = 960 tonnes day (24 hrs) at 28 knots.

So these appear to be Group West's estimates of Bismarck's fuel consumption?

Re: Fuel consumption Bismarck

Posted: Thu Dec 15, 2011 10:39 am
by Thorsten Wahl
yes the data were estimates from Group West, based on fuel consumption graphs/calculations, on wich I assume they had access


german ships use light fuel oil - density approx 0,82-0,86 metric tons per m³
so 7,700 m³ ~ 6,468 metric tons

calculation endurance/range
17 kn ---> 408 seamiles per day
300m³/day--->endurance 7700/300=25.67 days
range therfore 25.67*408=10,472 sm rounded down 10,400 sm

21kn ---> 504 seamiles per day
450m³/day --->endurance 7700/450=17.11 days
range therfore 17.11*504=8,624 sm rounded down 8,600 sm

28 kn--->672 seamiles per day
960 m³/day ---> endurance 7700/960=8.02 days
range therfore 8.02*672=5,390 sm rounded down 5.350 sm

28 kn were achieved at "Dauerlast" 113,000 WPS

Re: Fuel consumption Bismarck

Posted: Thu Dec 15, 2011 8:07 pm
by delcyros
Bestand 18.05. 00.00: 7700m^3 fuel oil

fuel consumptions:
May, 18th to 22nd of May each day 300m^3 = 1200m^2
May, 22nd to May,23rd with 21kts: = 450m^3
May, 23rd to May, 24th with 28kts = 960m^3

= 2610m^3 (indeed, 1,200 + 450 + 960 is exactly 2610m^3)
Bestand May, 24th, 00.00: 5100m^3 fuel oil (indeed 7700 -2610 = 5090, rounded up to 5100m^3)
calculation endurance/range
17 kn ---> 408 seamiles per day
300m³/day--->endurance 7700/300=25.67 days
range therfore 25.67*408=10,472 sm rounded down 10,400 sm

21kn ---> 504 seamiles per day
450m³/day --->endurance 7700/450=17.11 days
range therfore 17.11*504=8,624 sm rounded down 8,600 sm

28 kn--->672 seamiles per day
960 m³/day ---> endurance 7700/960=8.02 days
range therfore 8.02*672=5,390 sm rounded down 5.350 sm
this seems highly plausible to me in light of the report from Gruppe West.

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 1:01 am
by Herr Nilsson
Where does the 17 kts come from? :o

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 8:58 am
by Thorsten Wahl
MDV 601... mentions 17 knots in the text(but not as average).

Using a graphical solution compared to usual range/velocity charts, less then 17kn seem inplausible to me
Maybe possible speed could be 18 knots or more. But I decide to choose the lower speed as "worst case".

If the 300m³/day oil consumption refers to 18 knots potential range should be increased to ~11,000 sm (rounded down)

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 10:54 am
by Herr Nilsson
Bismarck's speed varied a lot during the first stage of Rheinübung.
You have to consider that BS had to run 25 kn in case of leaving Gotenhafen on May 19th at 2:00 h AM to be in the area of Cap Arkona on the next morning. You also have to consider that the Sperrbrecher hardly could run 13 kts. During May 21th Bismarck was at anchor near Bergen for 9 hours. I think it's highly speculative to infer from one mention of a dedicated speed at one certain time in the text that it was Bismarck's average speed during the first stage. I think 300 cubic meter is just a educated guess of group west (which did the calculation).

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 11:33 am
by José M. Rico
Yes, I agree with Marc.
We should take those speed/comsumption figures with care and keep in mind that they are, estimates, just that. It is based on data from the reconstructed KTB and post-action reports.

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 1:30 pm
by Thorsten Wahl
Thank you both for the comments and Marc also for the additional explantion of the 19,2% dockjard times at navweaps.

in general the fuelconsumption doesnt seem that much worse as it often is described. And one has to be carefully comparing different types of fuel(heavy fuel oil - light fuel oil) and their considerably different calorific value per given liquid capacity.

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 2:54 pm
by Herr Nilsson
The question is how many shafts and how many boilers. IIRC 10,400 nmi at 17 kts are possible, for example, but with two shafts running and a reduced number of boilers per power plant.

The values of fuel consumption are always in relation to 8,800 kcal/l LHV.

Re: Fuel consumption Bismarck

Posted: Fri Dec 16, 2011 3:37 pm
by Thorsten Wahl
for comparison
velocity range chart for North Carolina according Data from the above link in post 1
and Bismarck chart from data points at ~17kn??, 21 und 28

fuel capacity of NC was 1,879,751 gallons wich is 7,115m³

Re: Fuel consumption Bismarck

Posted: Sat Dec 17, 2011 11:38 am
by Herr Nilsson
I'm wondering about linearity.