Updates To Do List

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• [x] GATV
• [x] Agena SOT with Telstar Antenna (re-usable space tug for STS)
• [x] Gemini AORV
• [x] Centaur II & III (incl RL-10A-4N & RL-10B-2)
• [x] Centaur T
• [x] Atlas-Vega
• [x] Delta Fwoar
• [x] Vulcan by Superpenguin
• [x] Pioneer 5

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Transtage MOS ORV

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Jso on Centaur insulation

Treat the insulation like a fairing and dump it in the upper atmosphere/edge of space. It's pretty heavy so you don't want to keep it any longer than you have to. The way boiloff works is, heat from the outside is absorbed by the part's skin, the heat from the skin is absorbed by the part's internals, and the internal heat is transferred to the fuel causing it to boil. The jettisonable insulation slows down the skin to internal transfer, so it would seem to make sense to get rid of it as soon as possible when it's still hot from climbing through the thick part of the atmosphere. That way you jettison the heat rather than absorb it to the tank.

All of the other Centaurs have two layers of insulation, internal and external, and no weight penalty, so they are better equipped for long coasts.

Engine	Used On	LV	Notes
RL10-A-1	Centaur C	Atlas LV-3C	LR115 prototype
RL10-A-3	Centaur D, D1, G/T; Saturn SIV	Atlas SLV-3C, Saturn I	aka LR119
RL10-A-4	Centaur II, III, T	Atlas IIA, IIAS, III, V, Titan IV
RL10-A-4-1N	Centaur II, III Upgrades	Atlas III, V
RL10-A-5	DX-X, Delta Clipper		Sea Level Concept
RL10-B-2	DCSS	Delta III, IV
RL10-C-1	DCSS; Centaur III	Delta III; Atlas V

Variant	Engine	LV
Centaur D	RL10-A-3	LV3-C, SLV-3C
Centaur D-1A	RL10-A-3
Centaur D-1T	RL10-A-3	with truss mount on avionics block
Centaur G	RL10-A-3	STS
Centaur G Prime / T	RL10A-3 & A-4	Titan IV
Centaur II	RL10-A-4 & 4-1N	Atlas II, III
Centaur III (Common)	RL10-A-4-1N	Atlas III, V

• Centaur Avionics and Control System (1.875m payload truss variant switch for D-1T)
• BDB 1.875m Fairing Base
• Centaur-D 1800 Fuel Tank (insulation off for D-1T)
• Centaur Engine Mounting Plate
• RL-10-A Cryogenic Engines (x2)
• Centaur 1.875m Interstage (Centaur Long variant switch for historical builds)

Jso on Centaur insulation

Centaur D Atlas Centaur D is the first operational Centaur upper stage featuring two RL10-A-3 engines. Centaur D-1T, D-1A and D-1AR include various improvements to avionics, launch vehicle and payload interfaces but for BDB purposes they are essentially the same. Uniquely, Centaur D has jettisonable insulation to absorb heat and mitigate LH2 boil off during the launch phase. It should be treated like a fairing and dumped in the upper atmosphere to save weight before the upper stage burn.

**Centaur II

Centaur III (Common Centaur)

Centaur G Shuttle-Centaur (STS-Centaur) features a widened upper tank to fit the shuttle cargo bay.

Centaur G' / T Centaur G Prime features a stretched tank. Centaur T is a modified version for use on Titan IV. Both use the RL-10A-3 engine. Later versions of the Centaur T are upgraded with RL10-A4 engines.

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