Direct orbital transfers and fixed orbital ranges

EDIT: Py phone is spazzing out and keeps moving the cursor to random locatond. I hope everything is comprehansible.

Although a quick search hasn't found anything, something similar has probably already been suggested.

I'm talking about direct orbital transfers via hoffmans transfer orbit. The current system is sufficient for beta, but it is flawed. It's main drawback is the fact that it unnecesarily prolongs the game once the game reaches orbital and with more optimisations to come playing on a system with 3 - 5 planets with another 2 - 6 moons and moonlets doesnt seem that far fetched to me and having to go around the star every time you transfer orbital units is going to become very time consuming.

The other reason why this would work better is to create a bit more dynamic play. This would make orbal transfers a matter of strategic planing. The reason is that it would be tactically more sound to invade planets that are closer to yours first since long range transfers would require more time and would thus leave you exposed to a counter attack from a closer body than you are invading. Also since different orbits mean different speeds this would mean that a certain planet or moon may only be closest fora certain amount of time meaning that we would have invasion wndows during which an invasion of a certain planet or moon is most efficient.

Another thing thay would go with such a change is a fixed range on interplanetary nukes. Currently a nuke can hit the origin planet and any parent, sister or child planet (but not parents parent or childs child or sisters child).

Even if any of those 2 or other third party planets are closer than tour target. Giving interplanetary nukes a fixed range rather than a conditional one would create similar pros and cons as I have mentioned before in direct orbital transfers ( with the exception that nukes have limited range while transports mearly take more time to reach distant

I assume you mean a Hohmann Transfer Orbit, and that "hoffmans" is just your phone playing up.

A HTO is only viable if the planets are in the proper phase alignment. For example, in order to perform a HTO from Earth to Mars, the ideal time is just before Mars and Earth are on diametrically opposite sides of the sun. This results in the minimum delta-v required to make the transfer, but it does NOT necessarily mean a shorter transit time. The shortest possible transit time is a high-thrust brachistochrone trajectory, where the spacecraft fires its engines constantly whilst pointing at the target, then flips over at the halfway point, and fires constantly again, decelerating the rest of the way. This requires an absurd amount of delta-v, but it could certainly be viable for magical space robots in the future.

For point of comparison, current transfers use a low-pass bi-elliptic, which is an unusual choice as it does not minimise travel times, nor does it minimise delta-v budget. I assume it's done this way for convenience, and it would do a good job of maximising closing velocity with the target, which makes sense for asteroid smashing.

I think that what you are trying to suggest is that units should simply take a direct transfer. This would be where the ship performs a single burn in order to place itself on a parabola or hyperbola which intersects the target planet. If the destination is at the correct phase angle from the start, then this would be a HTO, minimising delta-v. If the target is in the wrong position, then the delta-v could be ludicrously high. However, I strongly doubt that delta-v is going to be explicitly modelled as it really would add a lot of complexity to the game, and make it much more about plotting efficient trajectories rather than outsmarting one's foes.

There are other issues with a direct transfer as well. The shape of the orbits will actually look a bit unintuitive as your target falls behind or catches up to the starting planet's angle. At the optimum phase angle, the apoapsis of the transfer orbit is equal to the Semi-Major Axis of the target, and the periapsis is equal to the SMA of the start. However, if the phase angle decreases (representing an earlier launch than optimum), then the apoapsis rises, while an increasing phase angle (a later launch than optimum) causes the periapsis to drop. Approaching the point of maximum delta-v (where the target and start are nearly in opposition/inferior conjunction, offset by an amount dependant upon their SMA difference) from ahead (a decreasing phase angle) means the apoapsis goes to infinity, while approaching it from behind (an increasing phase angle) means the periapsis goes to zero. If you are familiar with the mathematical concept of limits, then you will understand this represents a discontinuity. The only way around it is to special-case a range of phase angles with a different transfer orbit type. You would need to allow retrograde transfers, or go back to bi-ecliptics of some description, at which point it becomes more complex. You also need to factor in that direct transfers will often have two solutions, one where the spacecraft is heading out, and one where it is falling back in.

I have always liked the gist of the two ideas proposed here, namely that some planets are easier to reach from some planets than others, and that travel time should be dependant upon phase angle. I can think of a way to achieve the first simply enough, but the second is surprisingly complicated to do in a way that seems transparent to the player. I used to think that direct transfers were the way to go, however closer inspection reveals that this can lead to weird behaviour under some circumstances. I would need to do a fair few calculations to work out how to get the desired behaviour without causing unpredictable results. I'm contemplating a bi-ecliptic system where the periapsis/apoapsis varies substantially with the phase angle, but this is only an idle speculation.

Yes, but I thought HTO just meant direct transfer while being affected by some gravity (In this case the star , what I had in mind were obviously parabolic/hyperbolic paths you talk about).

And I wasnt talking about Delta-V being a resource, but rather time - it takes 5 mins to reach planet x, but only 30 seconds to reach Y at this point of time, but in another 15 mins planet X might only 2 minutes to reach, while planet Y needs 1 min.

EDIT: I don't know much about orbital mechanics, only what KSP and watching youtube has taught me (and as you see I apparently got some of that wrong). To me Direct transfer seemed logical. I had no idea that there was so much to it. Also - yay I'm not the only one to have to use limits on my field of studies