A few new ideas

Fidd · 03-15-24, 05:27 PM

137. Variable inertia (as a lobby setting) - "easy to realistic"

One of the less realistic aspects of WP is the lack of inertia. Inertia may be described as: Inertia is a property of matter1that describes its tendency to remain at rest or in unchanging motion unless acted on by some external force1.

In other words, a boat that is out of trim, will continue to rise or descend in the water column unless a corrective action is taken, such as adjusting the trim, but even then, there is a considerable lag between changing the trim, and it arresting the rise or descent. What we currently have is an almost instantaneous correction, without lag. The lag is caused because a u-boat displacing 870 tons (submerged), once it's moving in any direction, requires a very considerable and sustained force to stop it!

Inertia applies in every axis, for turning, for rising, diving, and for changes of speed. The corrective forces applied differ. So arresting an unwanted rise just using trim alone, is a small force, and then will take a good deal of time to occur. If on the other hand, the hydroplanes are used, then their effectiveness depends of the displacement from the neutral position, and also the speed of water passing over the 'planes. It follows from this that maintaining periscope depth with no forward speed should be very difficult, but doing so (say) at slow ahead, would be much easier.

Proposition: A slider on the lobby screen for "inertia". This would allow inertia to be set as it is now (easy) to fully realistic inertia. The effects of this would be to introduce an appropriate amount of lag between moving a control surface (rudder or 'planes), making a change to shaft rpm, or to adjusting a trim or MBT value. As the effect of inertia can be implemented simply by adding a lag value that's determined by the known inertia and corrective force, it may be possible to implement this without dealing in any way with the physics model. (If there is one!)

It has some interesting effects: For example, holding PD, one might want to trim slightly heavy, so the natural tendency of the boat is to sink slowly, then hold it at the correct depth with slight up 'planes. That way, simply reducing the amount of "up" planes will quickly offset any inadvertent rise.

Similarly, if DC's explode above the u-boat, it momentarily causes the boat to rise, requiring use of the 'planes to correct. Conversely, if the DC's explode beneath, the u-boat then develops a descent, and in both cases, the inertia of an 870 ton boat then requires considerable correction. It was entirely possible, and indeed there are many historical accounts of this, for WW2 submarines losing vertical control because too much correction was applied, leading to an increasingly divergent error in buoyancy, until the sub either broached the surface, or, sank beneath it's crush depth. Usually the former.

It may seem counterintuitive to be asking for "lag" when so much effort is being made to design it out, but in this case, I think it's worthwhile to make the operation of the boat configurable, and more interesting if desired. Of course this might better be something configurable on a per-boat rather than per-lobby basis..?

03-15-24, 05:27 PM	#26
Fidd XO Join Date: Apr 2005 Location: Blighty! Posts: 426 Downloads: 10 Uploads: 0	137. Variable inertia (as a lobby setting) - "easy to realistic" One of the less realistic aspects of WP is the lack of inertia. Inertia may be described as: Inertia is a property of matter1that describes its tendency to remain at rest or in unchanging motion unless acted on by some external force1. In other words, a boat that is out of trim, will continue to rise or descend in the water column unless a corrective action is taken, such as adjusting the trim, but even then, there is a considerable lag between changing the trim, and it arresting the rise or descent. What we currently have is an almost instantaneous correction, without lag. The lag is caused because a u-boat displacing 870 tons (submerged), once it's moving in any direction, requires a very considerable and sustained force to stop it! Inertia applies in every axis, for turning, for rising, diving, and for changes of speed. The corrective forces applied differ. So arresting an unwanted rise just using trim alone, is a small force, and then will take a good deal of time to occur. If on the other hand, the hydroplanes are used, then their effectiveness depends of the displacement from the neutral position, and also the speed of water passing over the 'planes. It follows from this that maintaining periscope depth with no forward speed should be very difficult, but doing so (say) at slow ahead, would be much easier. Proposition: A slider on the lobby screen for "inertia". This would allow inertia to be set as it is now (easy) to fully realistic inertia. The effects of this would be to introduce an appropriate amount of lag between moving a control surface (rudder or 'planes), making a change to shaft rpm, or to adjusting a trim or MBT value. As the effect of inertia can be implemented simply by adding a lag value that's determined by the known inertia and corrective force, it may be possible to implement this without dealing in any way with the physics model. (If there is one!) It has some interesting effects: For example, holding PD, one might want to trim slightly heavy, so the natural tendency of the boat is to sink slowly, then hold it at the correct depth with slight up 'planes. That way, simply reducing the amount of "up" planes will quickly offset any inadvertent rise. Similarly, if DC's explode above the u-boat, it momentarily causes the boat to rise, requiring use of the 'planes to correct. Conversely, if the DC's explode beneath, the u-boat then develops a descent, and in both cases, the inertia of an 870 ton boat then requires considerable correction. It was entirely possible, and indeed there are many historical accounts of this, for WW2 submarines losing vertical control because too much correction was applied, leading to an increasingly divergent error in buoyancy, until the sub either broached the surface, or, sank beneath it's crush depth. Usually the former. It may seem counterintuitive to be asking for "lag" when so much effort is being made to design it out, but in this case, I think it's worthwhile to make the operation of the boat configurable, and more interesting if desired. Of course this might better be something configurable on a per-boat rather than per-lobby basis..?