how far away is the "frontier" in YTU

[Spinward Flow]

My thought is to turn the 20-ish Imperial Sectors into subsectors, ditch the surrounding alien empires, keep it a Book2 ship universe, and cap TL at 11 (I'm not a fan of higher jump numbers, capital ships, battle dress, or PGMP/FGMPs).

From a starship construction perspective, limiting to LBB2 (standard) "letter drives" for engineering with a TL=B cap means ... the biggest starships that can be built are 2000 tons ... which makes for a decidedly "small ship TU" (by historical standards).

I wouldn't necessarily throw out ALL of LBB5.80 (et al.) ... so as to permit things like hangar berthing rules (not really addressed in LBB2) and fuel purification plants (a SERIOUS oversight that ought to have been included in LBB2!) along with small craft construction rules (albeit, limited to Drive-A/B/C only options in small craft!) and "aftermarket fuel tankage" options (LBB A5) can make for a really interesting "frontier feel" in a YTU.

If you need to limit the maximum jump number(s) ... for whatever reason ... there's 2 ways to do so.

The first (and most obvious) is that each LBB2 drive letter "step" amounts to a +1 increment on a scale ... and that scale is measured in 200 tons per increment.

1. A = 200 tons
2. B = 400 tons
3. C = 600 tons
4. D = 800 tons (TL=9 maximum)
5. E = 1000 tons
6. F = 1200 tons
7. G = 1400 tons
8. H = 1600 tons (TL=A maximum)
9. J = 1800 tons
10. K = 2000 tons (TL=B maximum)

From there, it's just straight division to work out the tonnage "range" that yields various drive performance codes.

• Drive-J = 1800 tons
  1. Code: 1 @ 1800 tons
  2. Code: 2 @ 900 tons
  3. Code: 3 @ 600 tons
  4. Code: 4 @ 450 tons
  5. Code: 5 @ 360 tons
  6. Code: 6 @ 300 tons

Some drive performance codes "don't work out" when you try to shoehorn them into hull form factors that are "too small" to make everything fit (drives, fuel, bridge, computer, crew, etc.).

If you fall back onto a portion of the LBB2 computer programming rules you can stipulate that even though a particular combination of jump drive letter in hull size form factor "ought to" yield a specific jump number (say, J4, just as an example), the computer programming needed to perform jumps of that range has not be developed/perfected yet ... and research into the topic is ongoing (and hasn't borne fruit yet, so still waiting for the breakthrough). That way, if you want to limit YTU to a J2 experience, you can do so ... even though a starship can have a drive installed in it that ought to be capable of a J4 performance ... if it ever has a fully debugged (and verified SAFE) J4 computer control program loaded into the main computer.

In other words, if you want, you can create a circumstance in which the "jump limit" in YTU is not a matter of hardware ... but rather one of software.
The machines are capable of J4 (in this example), but the software breakthrough needed to realize that capability hasn't been discovered/unlocked yet.