Nice..

I like..

I can't wait to see how you intergrate pitch and roll changes due to rudder and plane input.

Can't wait too :cool:
I need to add just few lines but I must think about it just a day or two more.
Now what bothers me are these planes on sail on original 688. What are they good for ?
They are too close to center of gravity so they can't affect pitch much.
Are they for lift ? Like wing for airplane ? Or maybe those small lift needed to balance buoyancy changes ?

They are called FAIRWATER planes. They effect depth without having as much an effect on pitch.

Here is a decent explaination of them for you:

http://yarchive.net/mil/sub_bowplanes.html

I invite everyone to read them as they talk about some of these 'wild' angles I have been describing

Cool link there. Brings a tear to my eye to see what Usenet was like before the unwashed masses ruined it.

I'm doing tests with bank angle. Now that really brings 'piloting' into it. Now I understand why they have 2 men driving the sub.

By my guess, there are 4 major forces effecting bank:

1) hydrostatic stability. Since center of buoyancy is higher then center of gravity, sub 'wants' to stand sail up even at zero speed.

2) hydrodynamic stability. Center of side-drag is similar to center of buoyancy for 688 .. near the centerline of the column-shaped body, or even higher because of the sail. Because of that, when water flows from the side of the sub, it will bank away from the water flow direction. This happens even in simple turn - in right turn sail banks to the right. Also if sub dives straight down, this helps keep the sail up. Sail is kind of flag so it turns to opposite of 'wind' direction.
If the sub surfaces straight up, this force would force the sail down (to 'flag' behind the main body). In this case hydrodynamic stability fights against hydrostatic stability.

3) screw rotation. Forces the body to rotate in opposite direction.

4) planes input. Used to fight all these effects.

Now amount of individual effects is quite mystery to me. I could compute at least hydrostatics quite well, but I would need to know where exactly point of gravity lies in 688. I don't know that. This too affects hydrodynamics. Screw effects ? No idea. At what vertical speed is the hydrodynamics stronger then hydrostatics ? No idea.
Planes effects .. is it possible to turn the sub upside down ? Can planes fight over hydrostatic stability ?

Anyway this really complicates all maneuvers. Simple right turn for example will bank the sub to the right which will make the banked rudder to pitch sub down. I know this really happens, but again, the amount is unknown.

Any ideas ?

I dont know if you have considered this till now, but maybe check out the aerodynamics and what happens with airplanes. For example the screw issue is quite similar if not the same with a helicopter.

While water as a fluid behaves differently in some aspects then air I think that some principles should be the same and thus it might be worth trying out some formulas for aerodynamics on your sub.

I have all the formulas. But not the parameters. And not knowledge enough to compute them. Normally you just measure real aircraft to get the parameters. Even if you can't fly real plane, there are dozens of simulations available, so even virtual pilot can know what feels right and what not.

With subs it's different. Everything is secret. There are no simulation of this detail (I mean public).

As for the bank effect .. after some tuning I came up with this subjective 'rules' (everything said concerns my sim, not reality):

1) Screw effect can be felt .. but it is not an issue except for flank speed, and even so you can ignore it, it will just bank you a bit.

2) Banking effect of the planes can almost do a roll but not really, at flank speed. However it is sufficient to counter all other banking effects except for high-speed corkscrew.

3) Corkscrew ? That's that funky think what sub does at high speed turns. Side flow banks it, banked rudder pushes sub down. At flank speed this can happen in seconds and you are past crush depth. I tuned it so that at 10 kts it is not really possible. Maximum rudder is possible. There are some minor banks but slow and easily to counteract with planes. At flank you better turn gently. It is possible to loose control. At least you are diving, turning, banking, not knowing what to do first. Engine stop, rudder center is first things to do. Correct pitch with planes, bank will correct itself. Emergency blow if needed.

4) Hydrostatic vs. hydrodynamic .. except for surfacing straight up with sub turned upside down there is no problem to keep sail up. At some extreme conditions the hydrodynamic effect can be felt anyway (and it's also responsible for the corkscrew).

Like this the sub is controllable and stable at most speeds, little wild at the flank. Anyway to keep bank zero requires constant attention.

Here is the live simulation with these bank effects http://roger.questions.cz/other/sim2.zip
Check the readme for new controls.

One little bug. When using the arrow keys to turn the right arrow makes you turn left and the left arrow makes you turn right. I was at flank and hit full rudder and didn't see much roll.


Oh I can send Akula model if you want.

Here's a good simulator

http://www.jhuapl.edu/websub/

Some other helpful stuff

http://robotics.ee.uwa.edu.au/auv/su...l/physics.html

Send whatever you have :yep: Anyway for me the arrow keys works correctly. Left moves rudder toward negative values. Right toward positive.

To get some decent bank:
Press 0 for flank speed. Wait till speed hits 30. Ignore slight bank to the right due to screw reaction. Press ']' for full rudder right. It should perform something like barrel roll.
Now this isn't realistic from many points of view. You would loose the air from balast tanks when upside down. Screw and planes would not work above the water (I don't test it now).

Are you sure you have the sim2.zip version ?

definately getting right is negative and left positive.

well clicked the link but the file sis still sim.zip not sim2.zip

This link seems to be it, the other is wrong(words are right, link is wrong). http://roger.questions.cz/other/sim2.zip

May I ask is there somewhere a write up of what the overall project plan is?

Are you developing a physics model of a modern sub for the sake of it?

Are you planning to connect physics model with realistic controls for the surfaces, tanks, and power plant?

Is there an AI on the way with scenarios and game play?

Is this just for personal fun or to prove that a public effort can go beyond SC/DW? (as I know that you have had your criticism of Sonalysts ... people always says it is easy criticize the works of others ... a lot harder to go do a better job yourself)

Thanks.

He's making a simulator. I think the grand objective is to have a working game with GUI, missions, etc etc. Check the file for a link to the website.

Yep working great, did a loop the loop :)

1) May I ask is there somewhere a write up of what the overall project plan is?

I'm aiming toward the ultimate subsim. Non-profit. Based on live feedbeck.
There is no write up since it's all quite unclear and open. Something like DW first .. something more later.

2) Are you developing a physics model of a modern sub for the sake of it?

Yes, exactly. This is just actual phase. Not final version of physics, just something which will allow next steps.

3) Are you planning to connect physics model with realistic controls for the surfaces, tanks, and power plant?

Not sure if I understand the question. Let's say I find DW approach to sub controls little simple. There should be more controls. Autocrew too, sure. But if you want to drive it manually, you should be able. Planes, tanks, power plant, you name it.

4) Is there an AI on the way with scenarios and game play?

Yes. Long time to go anyway.

5) Is this just for personal fun or to prove that a public effort can go beyond SC/DW? (as I know that you have had your criticism of Sonalysts ... people always says it is easy criticize the works of others ... a lot harder to go do a better job yourself)

Well .. I'm kinda programmer. I like programming. I like 3d graphics. I like aircrafts and now even subs. I always wanted to have some engine for simulations. To program things in simulation. Now everything got together. I have experience enough for 3D, simulation, I even have scripting language. So I just finally do what I always wanted. And since I really had some proud statements, why not make it submarine simulation first, and whatever else simulation later ? The basics are all the same. That's the main reason. The second reason is I'd like to play some new modern subsim, as hardcore as possible. Don't we all ? :rotfl:

I don't have much troubles with Sonalyst. I understand their approach. They do it for money. I don't. They can't provide support, even small and slow. I can (small and slow I mean :lol:). I can also go deeper, because general public is not my concern. So maybe Ubisoft will make some killer coldwar subsim before my is finished. Or SCS will surprise us after all. But there still will be place for my subsim.

Yeah .. sorry for the link trouble. I copied it from the previous post, modified the visible letters unaware there are some invisible ones. I even tested if the link works .. I just didn't check the filename it points to.

As for the loop .. the questions remains .. is this realistic or not ? Hope some bubbleheads see this soon. :|\\