If you want to see the drawings, don’t worry, they're just a bit further down. First though I want to explain what they are, to anyone who might not have come across this before.
Project Orion was a concept developed by ARPA, the USAF, and NASA to propel a spacecraft using nuclear detonations. Around 10 million dollars was spent on the program (94.4 million today) over the course of seven years, from 1958 to 1965, though development work started earlier, with the concept first emerging directly after WWII.
The program was initially started as an ARPA project, and continued like this until 1960 when it was transferred to the USAF, and then in 1963 NASA showed interest in it and they both ran it simultaneously until 1965. The vehicles developed by ARPA and NASA were civilian in nature and geared towards deep space exploration, while unsurprisingly the vehicles developed by the USAF were designed as warships, often equipped with nuclear missiles and casaba howitzers.
Here’s an excerpt from “Starfleet was closer than you think” by Major Brent Ziarnick and Lt. Col. Peter Garretson:
"America’s near-brush with Starfleet began with Donald Mixson and Fred Gorschboth, two young captains assigned to the Air Force Special Weapons Center at Kirtland Air Force Base. Their job was to investigate the military implications of Orion nuclear pulse propulsion technology, and wargame out a military concept for use.
They developed a plan for a three-tiered space force of dozens of Orion spacecraft deployed in either low, geosynchronous, or lunar orbit squadrons. This fleet would hold both nuclear surface attack missiles to provide a survivable deterrent without risk of being destroyed by a first strike, as well as space-based ICBM interceptors and mines (an early vision of the Strategic Defense Initiative) that could defend the United States from a Soviet attack in the event deterrence failed.
In late 1959, Captain Mixon laid out the evidence for General Thomas Power, the commander in chief of SAC, and obviously convinced him. On January 21, 1961, General Power signed a SAC requirement for a “Strategic Earth Orbital Base” (SEOB) based on the Orion propulsion system and roughly following the space force deployment concept. The SEOB would be “capable of accurate weapon delivery” to “include the capability to attack other aerospace vehicles or bodies of the solar system occupied by an enemy.” The SEOB would also be able to orbit “extremely heavy useful payloads” on the order of 5,000 tons.
General Power was not out there alone. He had the full support of the Chief of Staff of the Air Force, General Curtis E. LeMay. Writing in a 1962 letter to Power, he said, “I share your views regarding the potential of ORION”. Nor was it just talk: both the SAC commander and the US Air Force Chief of Staff were willing to put their money where their mouth was. In 1962, funding for the SEOB and Orion propulsion development together accounted for $1.36 billion (over $10 billion in 2014 dollars), or 18 percent of the total Air Force space development budget for fiscal years 1963–1967, as requested by LeMay in his Air Force Space Program."
The propulsion system itself, which represented the core around which the entire program was built, consisted of a vehicle with a massive ‘pusher plate’ behind it, connected to the vehicle by hydraulic struts. Nuclear devices would be ejected behind the vehicle, detonated, and the ejecta and radiation would hit the plate and impart momentum onto it. Subscale tests with conventional explosives were carried out successfully, and some of the best engineers and mathematicians of the time worked on the calculations for the full-scale system.
Despite initial appearances, it has been the stark opinion of every single engineer, physicist, and mathematician I am aware of who knew about the program in any significant detail that the system would have worked. While technical deficiencies in the design have been pointed out by many people, in all of these cases the people in question were either not technically literate or were unaware of the specifics of the system they were talking about, and every point I am presently aware that they have made has been rigorously and objectively demonstrated to be false by people who actually understand the systems.
The cancellation of the program was, contrary to popular belief, entirely political in nature. By 1965 the teams at NASA had developed an integrated plan for the development of a civilian Orion system, with orbital tests commencing in 1975 and it reaching initial operating capability by 1978. This plan included detailed analysis of program costs, timescales, development milestones, flight plans, and extremely detailed designs for various tests and test stands that would be necessary to prove the system on the ground.
Likewise, the common belief that Orion presented an environmental danger is objectively false. Analyses by some of the most competent scientists in the United States (who certainly know more about what they are talking about than anyone I’ve ever seen critiquing the project) show that if Orion was launched directly from the ground, the fallout produced would kill on average three random people across the world from increased cancer rates. Yet even this number was considered unacceptable, and plans for air-launching Orion after lofting it to altitude by conventional rocket boosters were created, which would have effectively reduced the fallout produced to zero. The nuclear devices used were low yield and relatively clean, and produced almost no severe EMP. The project conducted several studies into the Earth’s magnetosphere, and successfully identified large regions where Orion could activate its drive near to the Earth’s surface without the very small amount of fallout produced becoming trapped in the planet’s magnetic field, further reducing any risk.
It is worth noting that, despite not directly contributing to its cancellation, it is possible environmental concerns did so indirectly, by making the brass think that had the program gone ahead, the general public would be ignorant enough of the science behind it to erroneously believe it posed an environmental threat and therefore oppose the program.
However, the primary reason for its cancellation was political, stemming from a lack of a need for such vehicles by the USAF, NASA not wanting anything that could compete with project Apollo (in actuality it wouldn’t have just been a competitor; it would have completely obliterated almost all existing spaceflight programs, with a single Orion vehicle alone able to transport thousands of tons of payload to Saturn and back), and president Kennedy not wanting spacecraft armed with enough missiles to wipe out all life on Earth. It was estimated that the cost of developing Orion would have been comparable to the existing spaceflight programs of the time, and no one wanted to give up on those in exchange for Orion when they had already sunk so much cost into them.
To this day, Project Orion is perhaps the only time in human history where both a technological and societal leap forwards on the same scale as the industrial revolution, in this case a system literally capable of allowing human colonization of the entire Solar System, was given up for purely political reasons.
For more information, I recommend reading through the many articles on Project Orion over on the Atomic Rocketships website, here: http://www.projectrho.com/public_html/r ... lse--Orion
If you want to get an extremely long and in-depth analysis into both the actual program and the vehicles it produced, with hundreds of original and reconstructed diagrams, I would recommend purchasing a few copies of the relevant digital issues of the Aerospace Projects Review magazine by Scott Lowther. Here’s an excerpt written by him on two such issues:
"Aerospace Projects Review issue Volume 1, Number 4 V1N4
The primary article in this issue is a 58-page article on the development of Project Orion. This article covers the initial development of Project Orion, from the earliest configurations through to the near-final designs, test facilities, safety and environmental issues, and subscale flight vehicles. Vehicle scaling relationships, operating principles, and, published for the first time, pulse unit physics and interactions.
Copiously illustrated with photos, film stills, presentation graphics, diagrams and original drawings.
Aerospace Projects Review issue Volume 1, Number 5 V1N5
The primary article in this issue is a 71-page article on the late 10-meter Project Orion vehicles designed for the USAF and NASA by General Atomic. This article is packed with diagrams taken from official reports, as well as data, performance graphs, all-new reconstruction drawings and artwork. The Orion vehicle is described and shown in greater detail here than ever before in publicly available articles. Also includes information on 8-meter and 12-meter concepts for military applications as well as the baseline 10-meter design that was to serve both military and Martian exploration purposes. Launch vehicles, both solid and liquid rockets, are also described."
Alright, with that out of the way, on to the drawings! So far I’ve only completed one, but I’ll add more over time, with my goal being to eventually draw every Orion design that there are actual records of.
So first off, perhaps the second most famous Orion design after the civilian NASA version, the USAF Orion orbital battleship:
![[ img ]](https://i.imgur.com/pmi1Abj.png)
![[ img ]](https://i.imgur.com/FKJtFXb.png)
A lot of details about this ship are unknown, as they were destroyed or buried when the program shut down. However, we do have enough details left to get a pretty accurate picture of things.
The vehicles that the USAF came up with initially (circa 1960-1963) were gigantic; Orion is actually more efficient when scaled up, so they selected a 26 meter diameter vehicle. By this point ground-launch had been ruled out, so it was planned to be lofted to altitude by a giant chemical booster in the Nova class, with some plans pointing at NEXUS. The USAF came up with a 4,000 ton design at this diameter, which was basically just the propulsion system topped by an empty aeroshell where the payload would go. They then designed a battleship based on this, where said aeroshell was stuffed full of as many weapons as possible.
The baseline empty design is well-documented, with some diagrams showing the internal layout to such a high degree of precision the exact mechanical workings of the pulse-unit feed systems, pulse gun, and shock absorption systems can be ascertained with almost enough precision to literally build working examples. However, no diagrams survive of the armed version (though such diagrams did certainly exist at one point). Luckily, we know the external shape of the vehicle, and the internal layout as well as the arrangement of external features such as bay doors and missile cells can both be determined by examining written reports and accounts by people who worked on the project.
Two variants of the design were drawn up, a version with 1,115 tons of payload capacity and 15 km s-1 of delta-v, and one with 308 tons of payload capacity and 30 km s-1 of delta-v. It is unclear what “payload capacity” refers to in this context, but it can reasonably be assumed to be the total mass of all the systems stuffed inside the aeroshell, which include the weapons, crew accommodations, RCS, etc. Given the expected weight of these systems, it can be assumed that the typical weapons loadout quotes for the vehicle, of 500 missiles, three gun turrets, and a complement of landing boats, is in reference to the former variant.
Here’s a full set of known specifications for the 1,155 ton payload variant, taken straight from a USAF report, circa June 1963. Only one item in the report was redacted, which was probably the yield of the pulse units. And yes, the fact they regularly switch between imperial and metric units annoys me too. I have left everything in the original units however, in order to preserve the number of significant figures used.
(fyi, a “pulse unit” or “pulse system” is what they called the nuclear bombs that would be shot out the back of the spacecraft)
OPERATING CHARACTERISTICS:
Ship’s total gross weight: 4,000 short tons
Total engine weight (dry): 1,360 short tons
Weight of pulse systems (inc. coolant): 1, 411 short tons
Payload: 1,299 short tons
No. of pulse systems: 926
Mission velocity: 50,000 ft s-1
Pulse period: 1.1 seconds
Average initial acceleration: 1.25 g
Initial peak acceleration: 1.8 g
Final peak acceleration: 2.8 g
Initial velocity increment per pulse system: 44 ft s-1
DESIGN CHARACTERISTICS:
Pusher
Weight: 720 short tons
Diameter: 86 ft
Area: 5,809 ft2
Central thickness: 9.7 in
Edge thickness: 3.75 in
Material: T 1 steel
Peak pressure at center: 4.3 kbars
Total impulse on the pusher: 4.88 ⋅ 1012 g cm s-1
Maximum stress: ~60,000 psi
Pusher velocity: ~ +132 ft s-1, -118 ft s-1
Pusher acceleration (peak): 25.0 g
Total temperature-rise increment per explosion: ~0.56 °F
Maximum temperature after 500 explosions (uncolled): ~281 °F
Maximum operating temperature of pusher: 200 °F
Coolant (H2O) for 920 explosions: ~12 short tons
Protective oil deposit and ablation per explosion: ~1.5 ⋅ 10-2 g cm-2
First Stage Shock Absorber
Outside diameter: ~81 ft
Height: ~15 ft
Number of concentric tori rows: ~19
Number of torus layers: 15
Diameter of individual tori: 12 in
Tori material: Steel cloth, 0.010 in thick or Nylon cloth, 0.050 in thick, sealant 0.050 in thick
Total weight of first stage shock absorber: 60 short tons
Shock absorber travel: +6 ft, -5 ft
Normal pressure in torus: 85 to 100 psi
Normal temperature in torus: 160 to 200 °F
Gas coolant (NH3) for 1,000 explosions: 20 short tons
Intermediate Platform
Diameter: 82.5 ft
Depth: 4.25 ft
Weight: 60 short tons
Peak acceleration: 115 g
Second Stage Shock Absorber
Number of piston-cylinder assemblies: 12
Piston assembly weight (12): 35 short tons
Piston wall thickness: 0.375 in
Piston diameter: 40 in
Telescopic cylinder weight (12): 30 short tons
Telescopic cylinder wall thickness: 0.300 in
Upper shock-absorber cylinder weight (12): 45 short tons)
Upper shock-absorber cylinder wall thickness: 0.375 in
Total system weight: 130 short tons
Coolant gas (NH3): 22 short tons
Coolant system hardware: 10 short tons
Shock-absorber travel: ~ ±33 ft
Shock-absorber pressure: 450 psi
Shock-absorber peak pressure: 850 psi
Shock-absorber temperature: 300 to 350 °F
Pulse System
Number of pulse systems: 926
Number of reserve pulse systems: 18
Pulse-system weight (bare unit): 2,540 lb
Pulse-system hardware for conveying and loading: 76 lb
Pulse-system total delivery weight: 2,616 lb
Over-all dimensions: 80 cm diam, 87 cm high
Maximum acceleration (delivery): 200 g
Standoff distance: 172 ft
Standoff distance tolerance: 6.8 ft
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Average propellent velocity: ~107 cm s-1
Intercept half-angle: 14 °
Loading Mechanism
Breech-loading assemblies: 4
Loading chambers per assembly: 2
Time period between ejections: 1.1 s
Breech-chamber positioning time: 0.6 s
Breech-chamber loading time if 3 levels used: 2.7 s
Total weight of breech-loading assemblies (4): 7.0 short tons
Gas Supply and Ejector Valve
Gas-mixing tank volume: 600 ft3
Gas-measuring chamber volume: 120 ft3
Gas-measuring chamber pressure: 640 psi
Gas-measuring chamber temperature: 600 °F
Ejector-gas-valve total opening: 4 ft2
Average gas consumption per ejection: 80 lb
Ejector Tube
Length below pulse-system loading levels: 40 ft
Inside diameter: 32 in
Maximum acceleration of pulse system: 200 g
Muzzle velocity: 448 ft s-1
Weight of ejector tube: 4.2 short tons
Weight of plasma deflector cone: 1.0 short tons
Pulse System Storing and Conveying
Number of storage levels: 4
Number of conveyors on each level: 2
Number of pulse-system spaces in each conveyor: 140
Total pulse-system storage capacity: 1,120
Weight of storage compartment: 600 short tons
Pusher Antiblation Oil Spray System
Amount of oil applied per pulse: 178 lb
Spray velocity, radially: 70 ft s-1
Spray velocity, vertically: 14 ft s-1
Duration of spray between pulses: 0.65 s
Ablation oil used for 926 pulses: 82 short tons
Thickness of oil film (average): 0.0065 in
First-Stage Shock-Absorber Protection Tube
Length of tube: 26.0 ft
Normal extension below pusher: 6.5 ft
Inside diameter (extending through pusher): 4.0 ft
Weight of extension tube: 10.0 short tons
The exact contents of the payload are not available in such precision, however we do know some things about it:
The outwards appearance of the ship was that of the cylindrical propulsion module and a payload section above it, encased inside an ogival aerodynamic shroud, which would presumably be kept even after reaching orbit to act as shielding from micrometeorites, radiation, plasma angling around the pusher plate, and enemy fire. She would be launched from Earth structurally complete, though likely missing pulse units that would be delivered to orbit separately. The launch vehicle would have to have been massive; mentions are made to Nova and NEXUS. Operationally she would lurk in cis-Lunar space, and while the details of the crew complement are not available, she was reported to have berths for at least 6 re-entry lifting-body vehicles the size of PT boats (which I will also get around to drawing at some point, hopefully), each capable of transporting 20 passengers, which would indicate a crew complement of around 120.
Her armament is only vaguely defined, but known to include 5" guns off of contemporary naval warships, 20 megaton nuclear re-entry vehicles, and Casaba Howitzers (aka shaped nuclear charges, which direct the vast majority of a nuclear explosion in a single beam of plasma and radiation towards a target). The configuration I have drawn her in is a direct copy of a reconstruction made by Scott Lowther, based on what diagrams were available, written reports, and several phone calls with people who worked on the project, and represents a best approximation as to her actual design.