So, I cannot decide which FTL method should I use. I can do it easy way - just call it "Jump" and that's all. But I something more. So I want to combine some methods, like jumps with stargates or hyperlanes. Or combining all of them.
How can I have several FTL methods in the same story without conflict?
It's quite simple, there are several ways to archive the same thing.
For example, we can already travel on Earth using bicycles, motorcycles, cars, aeroplanes or boats, some of them faster than others.
Some FTL are faster than other FTL but civilizations doesn't want to share their technology.
Maybe each one has a diferent advantage and disvantage. For example:
Also, you can add cooldowns or warmup times for each drive based on a flat number or proportional to the travelled distance, the speed and/or duration at your choice.
Each method works using a different principle.
The sci-fi warp drive or the currently theorized Alcubierre drive use the principle of space-time distortion (primarily based on a gravitational distortions)
Wikipedia has already explained it perfectly.
Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space without breaking any physical laws.
The hyperdrive travel to another planer when the is not cap of speed or the plane is smaller than our universe allowing travel from one place to another using a shortcut.
The idea of a hyperdrive in most science fiction relies on the existence of a separate and adjacent dimension most commonly called "hyperspace" [...]. When activated, the hyperdrive shunts the starship into what appears to be another dimension, where it can cover vast distances in an amount of time greatly reduced from the time it would take in "real" space. Once it reaches the point in hyperspace that corresponds to its destination in real space, it re-emerges.
It's usually explained as:
Distances in hyperspace may be smaller than or geometrically inverse in relation to real space; it may provide a shortcut between two points in real space, thus effectively increasing the ship's speed by reducing distance travelled rather than time taken; perhaps the speed of light in hyperspace is not a speed barrier as it is in real space
And the hyperspace could be described as:
It is typically described as an alternative "sub-region" of space co-existing with our own universe [...]. [It] is most succinctly described as a "somewhere else" within which the laws of general and special relativity decidedly do not apply [...]. [...]
Instead of using the hyperdrive anywhere, it only works between specific "hyperlines" between gravity wells (solar systems). In order to travel you need to have one hyperline map that shows you the faster and safer hyperlines for your travel. Hypelines can be built artificially in solar systems without lines with the most expensive technologies.
I couldn't find an easy explanation on Wikipedia so I'll write my own.
The jumpdrive produces a distortion between two different points in the space-time effectively "touching" them, the destiny and the start point are merged for an instant being the same location at the same time. Then, the ship moves through this joint and reaches its destination.
A jumpgate or stargate, is a device able to create an Einstein–Rosen bridge portal (AKA wormhole), allowing fast travel between two points in space-
Give the various drives different characteristics, with the net effect that new drives are superior to old drives except that the old drives are somehow easier to invent/build/operate.
Step by step, restrictions are taken away. Someone who can build a third-gen drive would have no reason to use a first-gen drive instead. Possibly all the options are implied from an unified FTL theory, yet early tech cannot handle the precision manufacturing or energy requirements.
Some nation or species has better engine types. One would have to explain why nobody bribed one of their engineers or salvaged one of their wrecks, or why reverse-engineering is impractical. (A reliance on bio-tech beats steel in this application?)
As a slight variant on the above, different technologies have useful characteristics.
So scouts and many warships use warp drive, the remaining warships, special gate transport freighters, and small tramp freighters use hyperdrive, and freight and passenger liners use jump.
How can airplanes and cars exist in our universe? Each serves a different purpose. A car works great with short distances, but can't handle intercontinental travel at all.
Perhaps your different FTL methods work similarly.
If I want to travel to the other side of the galaxy a hyperlane may be too "slow". I would need to make a hyperjump. But why can't I just jump all the time? Perhaps the fuel costs are extreme, or the ship equipment is far too expensive. Perhaps jumps can only be made in certain places, and I have to take a hyperlane to get to the jumping point.
Alternatively, maybe I don't have my own ship at all and I am dependent on public FTL transport. Nobody is doing hyperjumps in my area of the galaxy, so I have to take non-FTL shuttle to the moon, a public hyperlane out of the solar system, get a seat on a hyperjump-equipped ship, and then charter a smaller vessel to take the hyperlane to my destination.
If you can think of more different FTL methods, then you can add them into the above "itinerary". The key thing is to consider the pluses and minuses of the various methods. Different methods work better under different circumstances, and the economic advantages of one over another are important to consider. You could even work that into your story: are the underclasses stuck with hyperlanes while the wealthy are zipping around in their private hyper-jumper ships?
