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Posted: Apr 13 2005, 12:42 PM
Member No.: 4
Joined: 12-November 04
Is the Soyuz Design a Copy of the General Electric Apollo Proposal?
The Russian Soyuz spacecraft has been the longest-lived, most adaptable, and most successful manned spacecraft design. In production for over thirty years, more than 220 have been built and flown on a wide range of missions. The design will remain in use with the international space station well into the next century.
But did the Russians steal the design from the Americans? When the configuration was first revealed in 1968, some industry insiders immediately noticed a strong resemblance to General Electric's losing Apollo spacecraft proposal. The resemblance was openly discussed by Phillip S Clark and Ralph F Gibbons in 1983. After the Soviet lunar program was declassified, and information on the design of the Soyuz lunar orbiter version was revealed, the similarities seemed even more marked.
No Russian source has ever acknowledged a possible connection. Decide for yourself!
The General Electric Apollo D-2 / Soyuz Design Concept
The fundamental concept of both designs can easily be summarised as obtaining minimum overall vehicle mass for the mission. This is accomplished by minimising the mass of the re-entry vehicle. There were two major design elements to achieve this:
Put all systems and space not necessary for re-entry and recovery outside of the re-entry vehicle, into a separate jettisonable 'mission module', joined to the re-entry vehicle by a hatch. Every gram saved in this way saves two or more grams in overall spacecraft mass - for it does not need to be protected by heat shields, supported by parachutes, or braked on landing.
Use a re-entry vehicle of the highest possible volumetric efficiency (internal volume divided by hull area). Theoretically this would be a sphere. But re-entry from lunar distances required that the capsule be able to bank a little, to generate lift and 'fly' a bit. This was needed to reduce the G forces on the crew to tolerable levels. Such a manoeuvre is impossible with a spherical capsule. After considerable study, the optimum shape was found to be the Soyuz 'headlight' shape - a hemispherical forward area joined by a barely angled cone (7 degrees) to a classic spherical section heat shield.
This design concept meant splitting the living area into two modules - the re-entry vehicle, with just enough space, equipment, and supplies to sustain the crew during re-entry; and a mission module. As a bonus the mission module provided an airlock for exit into space and a mounting area for rendezvous electronics.
The end result of this design approach was remarkable. The Apollo capsule designed by NASA had a mass of 5,000 kg and provided the crew with six cubic meters of living space. A service module, providing propulsion, electricity, radio, and other equipment would add at least 1,800 kg to this mass for the circumlunar mission. The General Electric D-2 or Soyuz spacecraft provided the same crew with 9 cubic meters of living space, an airlock, and the service module for the mass of the Apollo capsule alone!
The modular concept was also inherently adaptable. By changing the fuel load in the service module, and the type of equipment in the mission module, a wide variety of missions could be performed. The superiority of this approach is clear to see: the Soyuz remains in use 30 years later, while the Apollo was quickly abandoned.
Are Chinese engineers just copycats, blueprinting the Shenzhou after the Russian Soyuz spacecraft design?
Spaceships are spaceships, said Joan Johnson-Freese, chair of the Naval War College’s National Security Decision Making Department in Newport, Rhode Island.
Everyone is interested in how much of the Shenzhou is Russian and how much Chinese, Johnson-Freese said. If one country builds a 737 airplane and the other builds an Airbus, are they similar or different? How different would skeptics like a Chinese rocket to be before it would qualify to be "their own," she pointed out.
"Rocketry is rocketry, I'm told. And once the basic principles are understood, successfully launching a rocket means being attentive to literally thousands of details … and understanding the details. More rocket accidents are found to be caused from inattention to detail than faulty design." Johnson-Freese said.
Yes, the Shenzhou is very similar to Soyuz, Johnson-Freese said. "Is that wisely learning from others rather than reinventing the wheel, or does it indicate a lack of ability or inferiority? Depends on what you are looking to prove. If the latter, then I would suppose that concerns about Chinese military benefits from their manned space program are lessened," she concluded.
Safer than Soyuz
It's clear that the Shenzhou booster has gotten a technology makeover, said British space analyst, Clark.
"The Long March 2F has improved guidance and control equipment. They've upgraded the engines and have new computer systems onboard. Plus, of course, there's the launch escape system," Clark said.
Clark said that the Chinese have taken a different path in designing Shenzhou's escape system - a better approach than that adopted for Russia's Soyuz vehicle.
Thanks to an extra set of motors mounted on the booster's shroud, escape of a Shenzhou craft from a failing Long March can be done at a very high altitude.
"So in that sense, I think Shenzhou is even safer than Russia's Soyuz," Clark said.
Another design difference from Soyuz is Shenzhou's orbital module.
Once the Shenzhou 5 flight draws to a close, its forward module will be released, as has been the case in the last three of Shenzhou's four test trips. Packed with experiments, and powered by its own solar panels, the orbital module is likely to stay spinning around the Earth for six months. While floating through space, the Shenzhou segment can be maneuvered by ground controllers.