The Hyperspace Translation Drive came about because a faster than light drive was required for the core human space region that was slower than Traveller's standard Jump Drive. It owes its inspiration to both the Stutterwap from GDW's 2300 game and the keyhole wormhole drives present in Fire Fusion & Steel.
The drive itself is relatively simple to operate. Move your ship beyond 100 diameters of a significant mass, charge your drive system carefully (usually over a 30 minute period), energise the hull grid which will open a rift into hyperspace and your momentum will carry you through into hyperspace. Once the entire ship is beyond the rift boundary it slams shut behind the ship and the ships velocity somehow translates into a hyperspace pseudo velocity which roughly corresponds to about 0.5 light years in normal space transited for every 24 hours in hyperspace.
That's the easy part. In the early days of hyperspace travel a few things were discovered (not in order of importance);
1. The ships course was actually set in hyperspace and could be changed
using the ships manuever drive.
In human core space the problem of hyperspace navigation was partially solved by installing automated "beacons." The beacons are basically unmanned automated vessels placed about every 0.5 light years between designated routes. These vessels have a hyperspace translation drive generator which is fired off on a pre-determined frequency effectively producing a "pulse" in hyperspace. Every HTD beacon has a unique signature so vessels on regular routes astrogate from beacon to beacon (this is an Easy Astrogation task). Of course since ships sensors are somewhat unreliable in hyperspace occassional vessels do lose their fix on the beacons, (at which time it would revert to a Difficult Astrogation task to regain the course) A failure on this task means that the task can be attempted an 12 hours later to detect the next beacon. If this one also fails (another Difficult Astrogation task) the ship has moved too far from a beacon route to find it again. Effectively the ship has to drop back in to normal space to determine where the vessel has ended up. (This is treated like a standard Traveller misjump except distance is in light years, a rought direction is also determined and the GM selects the nearest star to this position to be the closest body to the ship.)
The Hyperspace Translation Generator
Volume of the drive is equal to the volume of the hull in cubic meters multiplied by 0.039 (Minimum volume is 10.92 cubic meters, equivelant to a 280 cubic meter hull.
Mass of the drive in tons is equal to the volume of the drive multiplied by 3.0
A constant power input is required for the drive. 9.8Mj is required per 14 cubic meters of displacement so for a 1400 cubic meter ship 98Mj would be required to open an entry into hyperspace and to maintain the hyperspace field. The power required is taken by dividing the total energy required by 1800, so in this case 0.0544Mw.
Surface area of the drive is equal to the volume of the drive divided by 3.0
Price of the drive is equal to the volume of the drive multiplied by 0.3 Megacredits.
This is the unit that when discharged through the surface portion of the drive opens the hyperspace portal. Its capacity is determined as above so in this example the capacitors must have a 98Mj capacity. Time to charge the capacitors is 30 minutes which is the minimum safe charge rate. Faster charge rates have been tried but so far no ship has successfully translated into hyperspace doing this.