Atlas - friznit/Unofficial-BDB-Wiki GitHub Wiki
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 4G, either 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. For a more precise estimate of when to stage the booster skirt for a given payload:
- Build the rocket with payload in the VAB
- Remove the booster skirt with its engines
- Reduce fuel in first stage until TWR is just great than 1
- Re-attach the booster skirt and make a note of the time remaining in stage burn (e.g. 30s)
- Refuel the tanks
- Launch and stage at the noted time remaining
Refer to Marcelo Silveira's Atlas Payload Performance graphs for details.
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
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.
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
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