Atlas revamp 2024

[zorg2044]

WIP build guide for the new Atlas parts. Some bits are still pending

https://docs.google.com/spreadsheets/d/1QKUCvDAlZr2Li7REsgmhNlqYa59Yy76t1sbaCrnTXrI/edit?usp=sharing

[friznit]

First Gen

Atlas A-F - Atlas D was the first operational ICBM and the starting point for subsequent space launch vehicle derivatives. Atlas B launched SCORE that replayed the first recorded voice message from orbit. Retired Atlas E/F later repurposed for variety of satellite launches. Mostly used solid kick stages for orbital insertion except Atlas 23F, which used Agena D to boost Seasat into orbit.

Atlas Able - cobbled together by NASA adding existing Vanguard second stage to a USAF launch vehicle. Didn't work.

LV-3A - Agena A upper stage was a stop gap until Agena B, which was flown by both USAF and NASA and culminated in the first successful flyby of Venus by Mariner 2. Agena D was initial step towards a standardised launch system, designed to fly on Thor, Atlas and Titan.

LV-3B - Mercury was first US manned (and chimped) space flights.

LV-3C - Centaur was first liquid hydrogen fuelled upper stage. Jettisoning the insulation on the way up sheds dry mass and allows for greater payload capacity.

Second Gen

SLV-3 - Standardised launch vehicle with Agena D upper stage. Successfully launched Gambit-1, Lunar Orbiter, Mariner 5, GATV and SNAP-10A, the first (and only) US orbital nuclear reactor. Also launched ATDA with no upper stage.

SLV-3A - Stretched "long tank Atlas" or "Improved Atlas for Agena", launched OGO-5 and some secret ELINT satellites.

SLV-3B - Take LV-3C first stage, add Agena D and an OAO-1 satellite all wrapped up inside a big fairing and lob into orbit at Gas Mark 5. Only happened once.

SLV-3C - Standardised launch vehicle with Centaur D upper stage. Successfully launched Surveyor, Mariner and Pioneer satellites.

SLV-3D - Similar to SLV-3C but with improved Centaur D-1A upper stage.

Atlas G / Atlas 1 - Basically SLV-3D but with a stretched tank. Branded as Atlas 1 for commercial launch services.

Atlas H - SLV-3D with a Multi Satellite Dispenser solid motor upper stage instead of Centaur.

Third Gen

Atlas 2/2A(S) - Upgraded Atlas with stretched tanks, new engines and a roll control thruster on the new Centaur II interstage replacing the old verniers. 2AS added four Caster 4A SRBs, two ground-lit and two air-lit.

Fourth Gen

Atlas 3A/B - New generation simplified "single stage Atlas" using a powerful RD-180 engine that would allow for removable of one of the two Centaur engines. 3B introduced the stretched Centaur 3 (standardised "Common Centaur")

[friznit]

Background

Originally designed as an ICBM, the iconic Atlas rocket (BDB Bossart) launched the first four American astronauts into orbit in Project Mercury. Atlas D derived variants have a unique stage and a half design, jettisoning the booster engines to save weight and using the sustainer engine alone to finalise orbit. As a rough guide, jettison the booster stage at 3.5 to 4Gs. This can be done manually or with the auto jettison option in the booster skirt Part Action Window. Burn time should extend from around 30s to 2 minutes at just above 1G.

Tags: Bossart, Belle, Inon, Hermes

First Generation

The first generation launch vehicles were derived from the Atlas D ICBM and used LR-89-NA5 booster engines with a single LR-105-NA5 sustainer. Initial attempts at using a liquid fuelled Able (BDB Alpha) upper stage borrowed from Vanguard were unsuccessful but development of Agena (BDB Belle) led to a true work horse launch vehicle. LV-3C is the original Atlas Centaur (BDB Inon) featuring the first ever liquid hydrogen upper stage.

Variants

Launch Vehicle	Boosters	Sustainer	Core Tank	Extension	Upper Stage	Remarks
Atlas A	XLR-89	None	A		Nosecone	Prototype A Red Skirt
Atlas B	XLR-89	XLR-105	B		"Chatterbox"	Prototype B Silver Skirt
Atlas C	LR89-3	LR105-3	C			D Silver Skirt
Atlas D	LR89-5	LR105-5	D			D Silver Skirt
Atlas Able	LR89-5	LR105-5	D		Alpha	D Silver Skirt
LV-3A	LR89-5	LR105-5	LV3		Belle A/B/D
LV-3B	LR89-5	LR105-5	D		Hermes
LV-3C	LR89-5	LR105-5	D	SLV-3B	Inon D

Basic Build Guide

• Atlas Able (BDB Bossart Alpha) uses a specific 0.9375m Interstage that interfaces with the Able's SIF Interstage Adapter.
• The conical adapter tank has variant part switches to fit Mercury (BDB Hermes) crew pod or the Multi Satellite Dispenser.
• Atlas LV-3C uses the Short Centaur (BDB Inon) Interstage and the shortest BT3 extension tank (SLV-3V Config) above the core fuel tank.
• Atlas A & B use the Prototype Booster Skirt. Almost all other builds use the standard skirt with the Default Config. The sustainer engine attaches directly to the aft adapter tank and then the booster skirt is placed on the top node of the adapter.
• Two "Crow" radial engines go on the triangular flat spots on the side of the core tank for roll control.
• Atlas ICBMs (A-F) feature a single separation motor at the top of the long side pod. Use a single Muo 5 sep motor for this.
• LV-3C (and all later Atlas Centaur variants) uses 8 retro motors to help with separation when staging Centaur. These attach to the core stage just above the booster skirt in 4 pairs of 2.

Atlas LV-3A Agena D

[friznit]

Second Generation

SLV-3 is the first dedicated satellite launch vehicle with uprated LR89-7 and LR105-7 engines and a standardised Agena D upper stage. It successfully launched Gambit-1, Lunar Orbiter, Mariner 5, the Gemini-Agena Target Vehicle and SNAP-10A, the first (and only) US orbital nuclear reactor. SLV-3C sports the Centaur D upper stage, later upgraded to the Centaur D-1A. Atlas G and it's similar cousin Atlas 1 flew until 1997.

Retired Atlas E/F ICBMs were repurposed for variety of satellite launches. They mostly used solid kick stages for orbital insertion except Atlas 23F, which used Agena D to boost Seasat into orbit.

Variants

Launch Vehicle	Boosters	Sustainer	Core Tank	Extension	Upper Stage	Remarks
SLV-3	LR89-7	LR105-7	LV3		Belle D
SLV-3A	LR89-7	LR105-7	LV3	SLV-3A	Belle D
SLV-3B	LR89-7	LR105-7	LV3	SLV-3B	Belle D	Belle D inside SLV-3B fairing
SLV-3C	LR89-7	LR105-7	D	SLV-3C	Inon D
SLV-3D	LR89-7	LR105-7	LV3	SLV-3C	Inon D1-A
Atlas E/F	LR89-6	LR105-6	F			Advanced Skirt
Atlas 23F	LR89-6	LR105-6	F	SLV-3B	Belle-D	Seasat Fairing
Atlas G / 1	LR89-7	LR105-7	LV3	Atlas 1	Inon D1-A	D White Skirt
Atlas H	LR89-7	LR105-7	LV3	SLV-3C	MSD	D Silver Skirt

Basic Build Guide

• SLV-3 builds are very similar to LV-3 but with various length extension tanks and the uprated engines.
• All SLV builds use the default Atlas D silver booster skirt.

Atlas SLV-3B uses a unique fairing that covers the Agena D (BDB Belle). Start by placing the small Interstage on the Agena bottom node, then attach the Adapter Base and finally place the Fairing Base over the top. Atlas 23F is a similar setup but uses the 1.875 Fairing Base Adapter set to 23F Seasat config.

Atlas SLV-3C can use either Short or Long Centaur (BDB Inon) Interstage.

[friznit]

Third Generation

Developed for the USAF MLV-3 competition in 1988, Atlas II features stretched tanks on both the first stage and Centaur upper stage and uprated RS56-OBA engines. The vernier engines are removed to make room for strap on boosters and replaced by a single roll control thruster on the Centaur interstage. The boosters are ignited in pairs, with the second set staging just after the first pair burn out.

Variants

Launch Vehicle	Boosters	Sustainer	Core Tank	Extension	Upper Stage	Remarks
Atlas 2	SR56-OBA	SR56-OSA	2	2	Inon 2 (2x R-10A3)	White Booster Skirt
Atlas 2A	SR56-OBA	SR56-OSA	2	2	Inon 2 (2x R-10A4)	White Booster Skirt
Atlas 2AS	SR56-OBA	SR56-OSA	2	2	Inon 2 (2x R-10A4)	4x Dioscuri-4A

Basic Build Guide

Atlas 2AS

[friznit]

Fourth Generation

After the merger of Martin Marietta and General Dynamics in 1993, the Atlas launch vehicle was simplified. The stage and a half design was replaced by a powerful RD-180 that allowed removal of one Centaur engine. With two engines available throughout the burn Atlas III does not need vernier engines or roll control thrusters. 3B introduced a stretched Centaur 3, standardised as "Common Centaur" for use on multiple different launch vehicles.

Variants

Launch Vehicle	Boosters	Sustainer	Core Tank	Extension	Upper Stage	Remarks
Atlas 3A	DR-180		3	3	Inon 2 (1x R-10A4)
Atlas 3B	DR-180		3	3	Inon 3 (1x / 2x R-10A4

Basic Build Guide

• Atlas III (BDB Bossart 3) uses 12 retro motors placed in pairs just about the joint between the core stage and the engine.

Atlas IIIA with Dual Engine Centaur II upper stage

[zorg2044]

Updated the build guide spreadsheet for the 2.5m parts.

SLV3-X is pretty straight forward. Only point to note is to use the Atlas II roll thruster. Ofc thats not period correct but all signs point to something roughly similar being used as there is no vernier.

The 5 engine Atlas is based on very early concepts before the design coalesced into what we know today. The design was volatile at that time and changed a lot. Even the fuel choice varied. The overall dimensions follow Ed Kyle's card. The XLR engine have the right Isp more or less although the thrust is lower than what Ed Kyle noted on Spacelaunchreport. Still it works in KSP. The XB-65 designation was in use for the missile at the time.

Users are probably best served by not focussing too much on this specific build but coming up with how the design might have evolved later. The original design used a much larger warhead too which is not represented here since most of that is part of the conical tank in our model and topped off with the smaller Atlas A instrumentation nosecone to complete the shape.

[zorg2044]

Updated build guide doc with CELV. More or less the same as before really, the tank lengths are the same as before but the extension tanks have been consolidated into B9PS switches.

The castor motor from the proposal is notional but the AJ60 is a good match to the propellant load as described by Ed Kyle. Details of roll control solution is unknown but the Atlas II thruster could be placed on the fairing base (maybe even 2x).

[zorg2044]

Expanded the Atlas II and III sections and clarified the upper stage options.

[zorg2044]

aaah I just realised you had already taken some of your screenshots before we had that discussion about the LV3 tank. With the latest corrections to the sheet I believe all the Atlas Centaur variants up to Atlas I should be using the Atlas D core tank rather than LV3. All the images show the shorter of the left side avionics pod on Atlas centaur vehicles. Sorry :P

[friznit]

Atlas Unflown

Background

Over the course of its long life, there have been many proposed Atlas designs that were never developed. Some are essentially early concepts for launch vehicles that flew many years later. Designs changed a lot over time so a degree of artistic license is encouraged when building these rockets.

Tags: Bossart, SLV3X, CELV

Variants

Launch Vehicle	Boosters	Sustainer	Core Tank	Extension	Upper Stage	Remarks
Atlas Vega	LR89-5	LR105-5	D	SLV-3B	Vejur	Optional JPL6K Third Stage
Atlas Vega Mercury	LR89-5	LR105-5	D	SLV-3B	Vejur	Hermes Lab & Crew Capsule
Atlas II-B	SR56-OBA	None	2	2 + SLV-3B	Inon 2	D White Skirt
Atlas SLV-3X	LR89-7	H-1D (1973)	SLV-3X (No Vernier)	SLV-3X	Inon D	D Silver Skirt
Atlas XB-65	XLR-89 x4	XLR-105	SLV-3X (Vernier)	SLV-3X + Short	Atlas A Nosecone	2.5m Booster Skirt
Atlas CELV	H-1D x4	H-1D	SLV-3X	SLV-3X	Inon G'/T	Prometheus 3.125m Fairing

Basic Build Guide

Atlas-Vega is a variant of Atlas LV3-C with a Vega (BDB Vejur) second stage powered by a Vanguard (BDB Viklun) first stage engine. In the three stage variant, a JPL 6K stage taken from Juno IV (BDB Chryslus) can be added. Vega is a drop in replacement for Centaur and uses the same interstage and fairing base under the avionics unit.

[Atlas-Vega]

The SLV-3X designation is reused often to refer to experimental designs. The 1970 SLV-3X is a "fat" Atlas SLV-3C with expanded 2.5m diameter (KSP Scale) first stage tanks and an H-1D sustainer engine in place of the LR105-7. A roll control system on the interstage is used in place of verniers.

[Atlas SLV-3X]

XB-65 is an early five engine concept boosted by 4x H-1D engines and a single H-1D sustainer.

[XB-65]

Atlas II Centaur G Prime (not to be confused with the later Atlas II that actually flew) was proposed for the USAF Complementary Expendable Launch Vehicle (CELV) competition in 1984. It features a 3.125m diameter first stage powered by 5x H-1D engines and 4x SRB's not dissimilar to the AJ-60A's used on Atlas V.

[Atlas CELV]

[zorg2044]

@friznit the XB-65 is all XLR89 and XLR105 not H1Ds (table is correct, the write up is wrong)

[zorg2044]

Also probably worth including Atlas K in the fictional list. Build should be same as the old one.