Looks like a screenshot from Sub Command, before Sonalysts fixed the 'flying sub' problem :lol:

Good ! Now we are getting somewhere. So I remove bank controls (hurray), increase hydrostatic bank stability a bit, lower screw reaction, and will tune it so snap-rolls can be managed with rear planes. I'll also add forward planes control.

Fatty,

With that screen shot, one has to ask what is the escape velocity of a sub to leave orbit? :)

---

I thought of one other question. I don't know how heavy the turbines are and how fast they rotate, but rotation creates centripal force which resists changes in momentum. An extreme example of this was in some WWI radial engine AC where instead the pistons were fixed and the cyclinder block rotated. This had a huge affect on handling. Do the turbines create enough centripal force as to impact the handling of the boat?

Please forgive all these stupid by analogy questions, but I imagine that enough stupid questions will illicit extremely intelligent and useful responses. :)

---

I like the lift wing behavior created by the hull. So, this is most pronounced at shallowed depths since the relative difference of pressure varies greatest the more shallow you are?

Helicopters exhibit a form of lift (I cannot remember the term "translational") when operating right above ground level (what make hover craft possible). So, do subs running close to the bottom shallows also experience a form of pressure lift from the bottom?

Thanks.

I think you are mixing two things ... one is the Ground Effect from bottom up to a certain altitude (exact numbers depend on helo) where the downwash from the helo creates additional lift and thus a helo might be able to hover while overweight but as soon as he leaves the cushion by going to high or going forward he goes down (unless the pilot is extremly good and the helo has some hidden power reserves).

The other is Translational lift ... The additional lift a helicopter gains as it moves from hovering into forward flight due to the increased efficiency of the rotor system.

Some good stuff on helos ..."Learning to fly helicopters" and "Chickenhawk".

I don't see how that ground effect could work for subs as they do not force water downwards. That is why it works in helicopters and planes. Helicopters quite obviously thrust air downwards, but airplanes do too. They just bend it downwards in an angle as it passes the wing. When close to the ground this downward airflow is somehow reflected (mirrored) upwards and decrease induced speed causing more lift for less effort.

I have no experience in sub physics but I can imagine this bernoulli effect sucking a sub to the surface that Bill mentions to work near the bottom too, only in the other direction. Quite fatally I presume.

Just shooting in the dark here.

One thing that is clear to me is that the subject of aerodynamics has been much better addressed both in modeling and documentation in flight/helo sims than aquadynamics has been for subsims. Most sub models have been pretty much flat and perhaps on par in their physics to the flight sims of the very early 90s. There have been only a few minor concessions such as momentum and surface state affecting surface cruise speed.

So, provided that Dr. Sid can get unclassified access to information he is quite likely to render a model of sub physics which is a few quantum leaps beyond anything seen in any game ever available on the commercial market.

Of course, one might ask in terms of game play how important is this. If you are not trying to dock the sub or conduct espionage at PD is this level of physics detail important to game play? I suppose that is hard to answer until such time that full range of behaviors are revealed. And again it goes back to what other aspects will be simulated. Recently, in another thread we discussed the cold war and the very close tracking of one sub by another. I would imagine that that of perhaps all possible areas might be the most sensitive to physics and fine control.

Well, sit back and enjoy the ride, since only Dr. Sid knows where this is all taking us! :)

I think getting the physics right is a fundamental building block for any simulation. Everything else in some way or another depends on how good that foundation is.

The most exciting aspect about this approach to me personally is the possibility of casualty and emergency procedure modeling that is far beyond anything we've seen in the modern subsim genre--actual accounting for flooding and changes in buoyancy, attitude, performance, etc. That sort of thing wouldn't be possible if too much of the physics is abstracted the way it is in the SCS series of sims. I'd rather see and experience the sub losing depth control than just be told by a voiceover that such control has been lost.

BINGO!

If you start off with a stong foundation, then you will get back in spades what you invest.

Couple this with the work he has done in ray path analysis, spice it up with what some of us can guide others on, and you will end up with something that will be a SIM and not an arcade game.

Since someone mentioned the comparison with dynamics in Flight sims in comparison to sub sims, it might be of interest to take a leaf out of X-Plane's approach to flight simulation. In contrast to pretty much every other flight simulator, X-Plane calculates the flight dynamics from the actual shape of the aircraft model in the sim, as opposed to most other flight sims where the 3D model and it's flight modelling are completely separate entities, and up until fairly recently, X-Plane was the work of just one guy too, which just shows you what can be done by someone working on their own.

From the website: 'X-Plane reads in the geometric shape of any aircraft and then figures out how that aircraft will fly. It does this by an engineering process called "blade element theory", which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations which are then integrated to velocities and positions... of course, all of this technical theory is completely transparent to you... you just fly! It's fun!'


More on X-Plane here:

http://www.x-plane.com/

:D Chock

BubbleheadNuke: I also derived some formulas for full auto TMA. ;)

Choke: For me, Orbiter is demonstration what one man can do. Challenge too.
As for dynamics based on 3d model, that would be very possible for subs too. But parametric model is easier to tune.

On the other hand I plan physics model based on parts. It is not so at the moment, this is something like first prove of concept.

Ship will be divided into parts. Part will be anything which can fall of, which can malfunction independently, and in same cases large parts will be divided into smaller parts so they can break apart. Sail or planes is the best example of such parts.
Dynamics will be computed for each part alone, then their connection will be used to affect the whole. Then you just loose the part, and everything works as it should.
The ship body is pretty large. For correct hydrostatic I should compute hydrostatic lift for all volume. If I divide the body into lets say 5 parts, each part will be easy to approximate by sphere for this.
3D model should reflect this too. This can thus be used for damage modeling too. You all have seen those pictures of frigate broken apart by mk48, right ?. Well it would not be 'exact' damage modeling, but this will allow pretty good damage model.
Also all sensors and crucial machinery would be parts, with 3d position and collision box. Missile hits frigate and blows sail part, but oops ! Antennas was mounted on it ! So no antennas any more. You manage to do lucky hit of submarine sail with 70mm shell. Now did it hit periscope tube hidden inside ? Did that maverick which hit frigate damage anything important ? Engine ? Tanks ? Missile stock ?

This in essence is what IL2 has. It's easy to do and it works great, for dynamics, damage control, it's also easy to create such model by non-programmer people (on DW we call them modders).

My goal is to make the configuration of the sim so strong, that no programming is needed. Possible, sure. But not needed. There will be parametric models of every sensor. Definitions of graphic interface, connection between the interface and sensor parts, I'm designing state-machine simulator which will be used on weapons (like you have to meet such and such conditions to do such and such action, which takes that time, moves that part, makes that sound and is visible here on the controls screen). Then there will be scripting language for extending this where needed, but only few expressions would suffice. No DLL (as in orbiter, for example), no need of compiler or anything.

I'd just like to add to what ML said. Physical fidelity is indeed necessary to realistically represent casualty situations involving flooding, loss of control, etc. Being a detail freak at times, I've always wished for a good diving station simulation that would let me operate the ballast control panel and trim & drain pumps to keep the boat in proper trim, the planes to control depth (depth keeping at PD in heavy seas is a challenge on the par with air-to-air refueling in flight sims), etc.

Remember how much bitching there was about the original physics model in Dangerous Waters? "Subs turn too fast", "It takes forever to change depth", "My boat is bobbing on the surface like a cork" ... ad infinitum. Players do care and a bad physics model can break a game as much as any bug.

:|\\

Seeing how far Dr Sid has come has made me put 3DS MAX back on my PC.

sid will I have to build my models any differently to take into account a frigate breaking apart? i.e. I'll have to break the hull into two or three sections so that it can break up in the sim?

Also if the physics model is correct then the general rules of physics should apply for any object in the sim whether surface, submerged or airborne so we don't get crazy behaviour of missiles and the like as we have in DW.

I don't know where Sid is at in terms of contributions to programming but surely I can't be the only model maker interested in doing stuff. At the moment I use .3DS files but maybe Sid can look at building the sim in such a way that GMAX the free modelling program can be used too.

When REALLY stomping on the power a 688 could roll quite a bit due to the sudden increase in torque, soon after the speed had caught up to the turns the ship righted itself and had maybe a degree or two of roll. I cannot remember it ever being a problem.

If I remember the books right, there WAS a 688 that had a 'trim tab' on a stern plane (starboard side) to dial out this slight roll. It was not worth the extra weight and complexity IIRC. Also, 637 class had counter rotating screws but they considered it too expensive and complex for general fleet rollout.

Xabba: I would not bother with hull parts at the moment. Shape and textures are the most of the work. To divide the model can be done at any time. But think about it. There will have to be some structures inside too :|\\
Those pivot points of animated parts are more important now. Some masts will come very handy soon too.

I hope there will be more modelers, but for the moment one good sub is enough. Also many poeple thinks they can model, but they can't. Look .. we don't even like some SCS's models, especially because of accuracy !

As for the 3d formats, I can implement and even reverse engineer almost any format (did it before). I have some experience with OBJ (almost any software can export to it), LWO, and now 3DS. GMAX should be no problem too, looks quite 'readable' in hexa. Any idea if it is described somewhere ?

Not sure since GMAX is the free baby 3D MAX I would have thought there was quite a bit of stuff on it.

I'll do the model pivots points tonight at work and e-mail before I leave, I'll also see if I can find some scopes I did.

As for internals I guess a few internal braces can be done and textured.