Thor
Thor (Fenris) began as intermediate range ballistic missle, and evolved through four basic core sizes into the modern Delta II (Daleth) rocket.
Able, Ablestar, Agena, Delta, TAT, Burner, too many designs...
The Thor (Fenris) Rockets use the Fenris-860 Adapter fuel tank, Fenris-880 Liquid fuel tank, Fenris-360 Liquid Fuel Tank, and the Fenris-215 "Odin" Liquid engine as a base. The Early rockets have a 4x Fenris-TF Aerodynamic Fins placed at 45 degree angles.
The upper stages consist of either the Alpha, Alphastar, Belle A, Belle B, or Belle D with an appropriate adapter between them. 3x Dioscurl-1 Solid Rocket Boosters can be used depending on payload.
Thorad/LTTAT Agena D, Delta
Delta, 1000-5000
Thor's core stage is lengthened a final time to become the Extra Extended Long Tank, giving us the Delta II. It's topped with an efficient Delta-K second stage, and an optional Star-48 (Regulus) kick motor.
The ultimate "med-light" launcher, the Delta II is a 1.5m workhorse, used for interplanetary as well as orbital payloads.
For easier assembly the Delta-K parts are named Delta-K-1 through Delta-K-5 from top to bottom. After the Delta-K is built the long interstage attaches flush with the bottom of the fairing ring. The two core tanks and RS-27A engine below that.
Early Delta II's in the 6000 series use nine Castor 4 (Dioscuri-4) boosters. The 7000 series uses three to nine GEM-40 (Ruby) boosters. The "Heavy" version uses the larger GEM-46 (Emerald) boosters.
The boosters cannot be easily placed due to the 9x symmetry of the mounts. The easiest way to assemble the boosters is placing radial decoupler aligned with the only mount on a cardinal axis. Add the SRB to the radial decoupler. Then, via the translation gizmo, vertically align the SRB using the tiny struts on the bottom and the red holes on the engine housing (it might have to be shifted towards the core to make the struts visually contact the holes). Separation solids aren't necessary if the radial decoupler is near the top of the SRB, but add them now if you want them. Once the first set of three solids is aligned, alt+click the decoupler to copy it, and proceed to place the other two sets of three. Holding shift will change the angle snap from 15 degrees to 5 - because the SRB mounts are spaced 40 degrees apart, this lets you accurately attach the remaining SRBs.
The usual arrangement is 3x, 4x, or 9x boosters. With 9x boosters, 6 light on the ground, and the other three in the air. The 6 spent boosters can be jettisoned then or all 9 can be jettisoned at the same time after the second set burns out.
Delta III modifies the Delta II by shortening and widening the upper half of the tank, giving a wider fairing base with the same amount of fuel. The Delta K second stage is replaced by a Delta Cryogenic Second Stage (in development). The GEM-46 boosters should be used.
A Delta III and Delta II
