View Full Version : Rates of climb and descent
07-12-2005, 04:55 AM
Having noticed a significant change from SC I set out to do some tests of the relative rates
Both at 100 ft. (Same locations) Descend to 300 ft. TA deployed.
Descend - SC 1.8 - 39 sec. DW - 1m 53 sec. (An increase of 250 % appx)
Ascend - SC 1.8 - 41 sec. DW - 1m 53 sec
Descend - SC 1.8 -44 sec. DW - 2m 19sec. (An increase of 330% appx.)
Ascend - SC 1.8 -44 sec. DW - 2m 19 sec.
At first blow this looks bad for the SW - further tests to 600 ft confirmed the disparity.
However it soon became apparent that the SW was taking much longer to level-off, particularly in the
last 20 ft or so. So when this was allowed for by measuring the time both took, to achieve the ordered depth,
but less those last 20 ft. both subs had almost identical performances.
This may not be new info. to many but others may wish to allow for this in the SW - those 20 ft. can account
for as much as a minutes loss of time, which could be vital in many situations. :know:
I cannot help but feel that 1 minute to travel 2o ft while levelling is a little 'unrealistic' ? :hmm:
07-12-2005, 07:38 AM
what about the speeds i made the akula hit 47knots while at flank and blowing ballast tanks
did the same for the sea wold and i hit 51 :o
07-12-2005, 07:47 AM
I guess the seawolf is simply faster.
07-12-2005, 08:06 AM
Then that is still like in SC, Kapitan, when performing E-Blows from a sufficent depth.
Good point Bellman. Did you use the same speeds the same map and the same location (water currents) and did you repeat the test?
If so that's curious that the SW takes more time to level off, as the inertia should be lower with lower tonnage and dimensions i thought? :hmm:
07-12-2005, 08:46 AM
in sc i never managed to pass 37 knots so ?????
07-12-2005, 09:32 AM
with the Akula II load 100% air, go deep and do an E-Blow: 40 Knots. SW i didn't try but i remember bewteen 40 and 50 knots.
07-12-2005, 09:34 AM
i did an eblow and managed about 47 knots
07-12-2005, 10:03 AM
Kapitan i meant in SC...
07-12-2005, 10:07 AM
lol sorry it me who become confused
07-12-2005, 11:19 AM
Nexus7 - yes to all.
I am converting to the Ak for DW after concentrating on the SW in SC/SCX2. :cool:
As you would need to know the relevant comparative performance characteristics I wondered whether SA
had adjusted anything (else) in favour of the Ak. :D
I cannot understand the protracted SW leveling off process, which I have replicated several times. :hmm: :hmm:
07-12-2005, 11:22 AM
why is it when i do e blow in dw my stern is the first thing to bounce out of the water ?
07-12-2005, 11:24 AM
The hot weather here has led to small increase in alcohol consumption, so I am rather concerned that I now see TWO sheep.
I am sure there was only one before ? :roll: :roll:
Do you intend to let them breed ? :o
Will your posts be guarded by massive flocks of sheep ? :D
07-12-2005, 11:27 AM
oooo yeah :P lol they will breed untill they fitt on subsim no more lol
07-12-2005, 11:30 AM
:huh: :stare: :stare:
Good on you - meatey :rock: :rock:
Sorry typo - matey. :doh:
07-12-2005, 11:31 AM
i fancy lamb for dinner
hear lenie lenie lennie come to uncle kapitain :D
07-12-2005, 11:38 AM
I've got to chop this conversation while its in mint condition and before it gets too saucey.
I'm on the side of lamb and this cut-lets me go to my meal.
All the breast. :up:
07-12-2005, 11:40 AM
07-12-2005, 11:40 AM
07-12-2005, 12:03 PM
This is getting very scarey - the wife gives me countdown to the meal and I casualy say ' Whats it to be '
Aaaaah ''Lamb chops'' she says. :roll: :roll:
I think that you've got something here - used to be a Stage Act called 'Think a Drink' Audience shouted it - he poured it ! :up:
Now I dont want to lead you here but tomorrow can you swap those critters for prime beef stock or photos of a distillery ? ;) ;)
07-12-2005, 08:41 PM
Its a great pity my 'sheep counting' got in the way of the discussion - put it down to hunger. :lol:
Anyways extending my point about Depth changes and Course Changes in an earlier post (Xab) - here is an excellent post last night from Marconi at the Battlefront forum :-
'' No new posts in this topic for quite awhile. Here're a few musings from a 688/637 class qualified Diving Officer of the Watch:
Acceleration of the SSNs in DW is a bit optimistic, but not as much as you might think. Attack boats CAN build speed very rapidly in an
emergency, such as torpedo evasion, but will nearly always cavitate, regardless of depth. In addition to making alot of noise,
cavitation wastes power, like a car burning rubber. Under normal circumstances the throttlman builds turns more slowly, following the
cavitation curves, which vary significantly with depth.
Ordered depth excursions in DW are terrible, and the virtual DOOW needs to go back to Submarine School for retraining. Real depth changes are made with good use of ship's angle to drive the ship to the ordered depth. A common rule-of-thumb is 5 degrees up/ down angle for each 100 ft/30 mt of depth, upto a max of 15 degrees (25-30 degrees during an emergency blow). In DW the depth excursions are done with stern planes flailing around to keep the boat at zero bubble +/- 1 degree. PITIFUL.
Sonalysts have significantly underestimated the effectiveness of the SSN's rudder, which is huge in proportion to the ship's size. Submarine course changes in DW aren't handled very well, almost as badly as depth changes. One glaring error--at high speed (>20 kts) no sane Officer of the Deck would order a turn using full rudder, except to avoid an imminent collision. The drag of the rudder at full throw is enough to slow the ship by 50-60% during the turn. At >20 kts you can turn very quickly with 5~10 degrees rudder, while keeping most of your speed in the turn. DW's virtual OOD needs to learn this. Also, the rudder is much less effective then the ship is surfaced,
since almost half of it is out of the water.''
'Never send to know for whom the bell tolls...'
07-12-2005, 08:50 PM
:) ........the thread for 'Sub Performance Realistic ?' is:-
07-13-2005, 07:17 AM
Great info! :up: So subs should turn little faster, accelerate slower (but not as slow as I though ?) and the methode of depth changing (autopilot) should be reprogrammed ? (but isn't the last mostly cosmetic change ? should subs only behave different or also have different diving/surfacing times?)
Best would be if he could propose what should be in the game values of stop to flank time or degrees/sec in turn, is it possible ?
P.S. So maybe.... cavitation should depend not only on speed at given depth but also on combination of speed to throttle setting at given depth ?? I think it's not hard to do (but in game code so by Sonalysts). For example when shallow you could set throttle to speed only 5kts greater that your actual speed (or the throttle lever up by one) to not cavitate, only when you accelerate you can add some more and so on. On greater depths like 300-600ft you could set 10kts or 20kts more than you have now (and more radical throttle lever movement, by two or three stages), only on max depth you could order any speed you want (set flank from stop) without cavitating ? How this sounds ? :)
07-13-2005, 03:28 PM
I read that post on Battlefront as well and I'm not sure how much could be tweaked in the DBs to produce the results Marconi is critiquing (but perhaps quite a bit could be done)?
But to say that SC did a much better job of simulating underwater performance (Bernoulli's Principal - bouyancy/lift, the effect of mass and surface area, etc. etc) than DW does currently is highly unlikely. The reason is that DW has a far more robust physics implementation than SC ever did (i.e. the dreaded airborne submersibles are evidence enough in SC :oops: ).
Perhaps some of the coefficients or variables in the equations that we simulated are a bit off from real life (I'm not sure, but I'll concede that it's certainly possible) but I would imagine that tweaking the numbers in the DBs will only work to some level for some situations (i.e. fix one instance to make it realistic but it breaks another one)...
The physics engine is a definite upgrade and is based off of multiple real-life formulas for all sorts of physical criteria - so in that sense it "should be" vastly more accurate than the one in SC...
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