[REL] Thomsen's Ships V3.1 is out! All credits to H.SIE (10/12/2008)

[h.sie]

hi mikhayl:

I agree. I've stopped programming my tool which automatically sets values in the sim-files, because there must be research BEFORE programming. i have no experience with ships, except my rudder boat for fishing purposes, but according to my "feeling", i would estimate, that a speed reduction from 15 to 10-12knots would be okay when zigzagging.

a friend of mine is commander of a (real) frigate. i meet him next week and i'll ask him about that problem. in the next time, i will play around with the params (mass, drag, eng_power etc.) in the unit_Ship section of the sim-files for diffferent ship types. perhaps we could exchange experiences. but i don't know if it's polite to use this thread for that?

h.sie

[Sag75]

Hi to all, I tried to modify the mass of U-boat. I found very strange behaviours.

If I increase 10fold the U-boat surface desplacement, the Uboat floats on sea surface!
If I decrease 10fold the U-boat surface desplacement, the U-boat sink as a rock!
But, if I increase the U-boat mass (the vaule before surface/immerged nodes), the boat goes down as a rock!

And there isn't any value apparently linked to inertia momentum. SH3 plays with engine power and xyz drug coefficients, but probably the mass is linked only to floating properties..:hmm:

it's weird. Probably U-boats are not usefull for this kind of tests..

[Hitman]

You can do some neat stuff with mission Editor.
A usually use it to do Stunt flying for aircraft!
I'll script 5 aircraft flying in a wedge and have them increase speed and
start a split as they climb!

It's awesome to watch!
Sometimes I add Smoke in different colors just
for the thrill!
FPS really takes a hit but it's so Danged COOL!!

Here's an early example of Stunt Flying.
http://s108.photobucket.com/albums/n...ent=Fly_By.flv

Wow, "GWX 3: Secret Weapons of the Luftwaffe" is coming

[Philipp_Thomsen]

1. The rudder drag is related to how fast the ship will turn, and have almost nothing to do with how much speed will the vessel lose while turning.

2. A ship like a battleship, with a lot more power-per-ton coeficient than a merchant, with 3 propellers instead of one as a merchant, and with a lot better hull for speed, while turning would likely lose half of it's speed. I have those numbers. Now, are you telling me that a big tanker, doing 15kts, (which is a great speed for a tanker, but would be impossible while turning), and dropping to 5kts while zig-zaguing is absurdly irrealistic? You said yourself that you don't know what would be the accurate speed for a ship like that in conditions like that, so why are you questioning so hard about realism?

3. The rudder drag for merchants is set at 0,02. If you decreases that, the ship turning radius will become VERY large, there goes a lot of irrealism. I tested a lot this parameter, 0,02 is the smallest value you can imput on merchants. The stock value/gwx value would be 0,03.

4. You guys are talking beautiful maths, but sh3 don't allow us to party around with zillion values. If you open ship.sim in s3d, you'll see about 20 values, and only 2 of them are related to how much speed ships will lose while turning.

a) the engine power: sure, increasing the engine power to a kazillion would make the ships mantain the same speed while turning, but also would make them behave like a jet-fighter. The engine power as it is right now is the closest to realistic accelerating we can have.

b) the drag left-right: the ammount of drag between the hull and the water when moving left-right. In other words, the ammount of friction between the hull and the large ammount of water that is deslocated while turning, cos the ship is "pushing" tons and tons of water out of the way when turning. Remember, a ship does not turn like a car, front first cutting the water and the rear follows. Nope. The front does nothing, the rear pushes left or right, moving zillion tons of water out of the way, changing the heading. The value in my mod is 0,75. If you decrease that, yes, the ships will start to turn a little bit faster, but this is also the value that controls the "bobbing", so if decreased the ships would be back as gwx, behaving like rubber ducks in a bathub. Pointless.

Now, what can be done to improve the ship's maneuverability while turning, that would not be realism killer?

Increase the engine power by 100%. Yes, doubling the value.

This mod took the engine power and reduced to 10%. Now if you double it, you'll have about 20%. And 20% will not ruin too much their acceleration and breaking abilities, and will improve their speed while turning.

Why?

Simple, they will have more engine power, and that engine power will be able to sustain more speed while turning, the relation between power/drag will be bigger.

While hasn't it been done already?

I'm waiting h.sie finish his tool so I don't have to manually change 200 ships.

[Philipp_Thomsen]

Originally Posted by Sag75

Hi to all, I tried to modify the mass of U-boat. I found very strange behaviours.

If I increase 10fold the U-boat surface desplacement, the Uboat floats on sea surface!
If I decrease 10fold the U-boat surface desplacement, the U-boat sink as a rock!
But, if I increase the U-boat mass (the vaule before surface/immerged nodes), the boat goes down as a rock!

And there isn't any value apparently linked to inertia momentum. SH3 plays with engine power and xyz drug coefficients, but probably the mass is linked only to floating properties..:hmm:

it's weird. Probably U-boats are not usefull for this kind of tests..

If you increase 10 tons in the displacement, you also have to increase 10 tons in the mass. Otherwise, the uboat becomes umbalanced and sinks, or floats.

[Philipp_Thomsen]

Additional info:

The merchants have a particular maneuverability. Destroyers have another. Escorts also are different from destroyers and merchants. Battleships too.

So you cannot just find a right value for one ship and apply to all the others.

And no, I don't mind this kind of discussion in my thread. It's actually healthy. Like I said before, any kind of feedback can be constructive for the next update.

And like I said so many times, none of my mods are finished. They are constantly upgrading, based on feedback and discussions like this.

[Sag75]

"If you increase 10 tons in the displacement, you also have to increase 10 tons in the mass. Otherwise, the uboat becomes umbalanced and sinks, or floats."


thanks, I'll test changing both

[h.sie]

I ve made a test scenario, in which a troup transporter suddenly had to accelerate from 1kn to its max. speed of 17kn. wind: 15m/s comes from ahead.

with eng_power = 10000 (original value) it accelerated to 17kn in a too short time.

with eng_power = 1000 (10% value from PT) it accelerated slowly, but it did reach 17kn a long time later - as desired!!!

i cannot believe that. in my opinion this is impossible in real life, because the machines have to overpower the speed-proportional resistance of the water. I'm sure, that in RL an engine with only 10% power can never reach the same max. speed as a 100% power engine (this is only possible in an ideal system without resistance). if weak engines lead to the same speed, there would be no need for strong and expensive machines.

but in sh3 it seems to work, perhaps because of a very simple physical model implementation.

[Sag75]

Originally Posted by h.sie

I ve made a test scenario, in which a troup transporter suddenly had to accelerate from 1kn to its max. speed of 17kn. wind: 15m/s comes from ahead.

with eng_power = 10000 (original value) it accelerated to 17kn in a too short time.

with eng_power = 1000 (10% value from PT) it accelerated slowly, but it did reach 17kn a long time later - as desired!!!

i cannot believe that. in my opinion this is impossible in real life, because the machines have to overpower the speed-proportional resistance of the water. I'm sure, that in RL an engine with only 10% power can never reach the same max. speed as a 100% power engine (this is only possible in an ideal system without resistance). if weak engines lead to the same speed, there would be no need for strong and expensive machines.

but in sh3 it seems to work, perhaps because of a very simple physical model implementation.

unbelievable.. I'm agree with you about RL! but that is in SH3! thank you for your experiment that give us the confirmation that drag in SH3 behaves in a different way by RL!

So... just a thought :hmm: .. is drag in SH3 more like an inertia momentum ??

..and probably the SH3 water has not friction!! (I can stop the boat by stopping the engines probably because of drag value assigned to my boat, and not by the effect of a water value :hmm: ...?)

[Philipp_Thomsen]

I told you guys about a zillion times, but you had to go test yourselves. Now you're beggining to understand the problems I'm facing.

Originally Posted by Mikhayl

Sorry but that's wrong. The difference between 5 and 10 knots is not what I would call "almost nothing". With an important rudder drag the rudder acts like a hydrobrake when the ship starts turning, so yes for the second part you're right, you would need more power to overcome that "brake".
I may not have historical data but hey, if you're trying to evade torpedoes common sense surely doesn't dictate that you should slow down to a crawl

Btw I'd be curious to know your source on a battleship losing half its speed because of it turning, that contradicts the few things I've read on the subject :hmm:

But you're not understanding. You cannot change the rudder drag, cos otherwise the ship won't turn. If a ship turning radius is 1 mile with 0,02, it will be 2 miles with 0,01.

The data is somewhere on this thread...

[Philipp_Thomsen]

Originally Posted by Mikhayl

I do understand, stop thinking you're the only guy with a brain
In the post you quote I say that we need more power to overcome the problem, not less drag on the rudder. It would give realistic zigzags but unrealistic turning radius (Titanic had a turning radius of about 700m it seems, so the game figures look enough to me).

About the data you're talking about, if you care reading it you'll see that it contradicts your claim of "half of the total speed loss", so yet again, we need more power, or wholy different formulas

When I say half, it's a gross value. It's not exactly half, but close to that.

Yes, 20% of engine power is what we need, and I had it planned for two weeks already. Just don't have the time to do it hand ship by ship.

[Sag75]

I GOT IT!!

I increased the mass and surfaced/submerged desplacement by 10fold of U-boat VIIb.

Results.

-Stock (default) values:

1)
0kts->17kts in 30" , 300m run
during acceleration to max speed (ahead flank), the boat reaches 7kts in 4", 10kts in 6", 17kts in 30".

2)
17kts->0kts in 6'
during decelaration (engines stopped), the speed drops at 10kts in 20", 5kts in 1', 0kts in 6'.


-10fold mass and desplacement increase:

1)
0kts->17kts in 5' , 3000m run!
during acceleration to flank speed, the boat was at 7kts in 20", 10kts in 50", 17kts in 5'.

2)
17kts->0kts in 30' , 4500m run!
during deceleration (engines stopped) the speed drops to 10kts in 3'30", 5kts in 10', 1kts in 30'.


Moreover I looked into 12kts wind sea. The 10fold mass U-boat was feeling more heavy. Anyway, She was taking up to 10minutes to submerge!!

No modifications in turning rate/radius observed!


Conclusions.
The mass/desplacement appears linked to inertia in SH3, and appears have an heavy effect on acceleration/deceleration behaviour and a minor effect on pitch/roll stability.

I would suggest to increase the ships mass/despacement to change the acceleration/deceleration properties instead of modify the engine power (that might be increased close to the default value).

[Philipp_Thomsen]

Follow me...

Mass 10, engine power 2. Mass/Engine = 5.
Mass 100, engine power 20. Mass/Engine = 5.

So what's your point?

[Sag75]

Hi PT, yes you are right,

but just consider this: in the mod, the acceleration is slow down acting on engines power. But this has a somewhat effect on ship speed: for instance I played in the single mission Bismark, and all battleships were cruising at 3kts! I encountered the Aquitania and She was travelling at 3 kts near Gibraltar in heavy sea!

In other words, an engine power set at 2 (your example) could not have enough propeller torque to permitt the ship cruising in some sea state!


So, in order to slow down the sport-car acceleration and to permit a ship to decrease slowly the speed, (but without penalizing other characteristics like propeller torque) it might be better arise the engine power to default value and increase a lot the mass.

(probably in SH3 1kg is not modelled as 1kg! I mean, a 10.000ton ship maybe is handled in SH3 lika a 2000ton, even if the .sim value is 10.000!)

[Philipp_Thomsen]

You're still not getting it.

Increase the ship mass and engine power will result in the same problem.

Engine power 10 and mass 10.000 is the same as engine power 1.000 and mass 10.000.000. All the maneuverability and sailing behavior will be the same. Can you see?

Like a car with 500kg and 80hp, and a truck with 5.000kg and a 800hp engine, they will have the same hp-per-ton constant.

Reduce the engine power or increase the ship mass is exactly the same thing.