n the year 1950 on June 27, the first expedition to the Moon from the planet Earth was successfully launched.
Numerous articles and programs have documented this momentous event, but over sixty years later, much of the technical specifications for the Atomic Rocket Ship Luna remain unknown. This post attempts to use publicly available information about the Luna and attempt to derive performance and flight data for this seminal event.
The Luna had a length of 150 feet (45.72 meters) with the cylindrical main body 18.3 feet (5.578 meters) in diameter at its widest point. Each wing is 25.53 feet (7.78 meters) wide with a total wing span of 69.36 feet (21.14 meters) The rocket’s dry mass (empty of all propellent) is 50 US Tons ( 100000 pounds, 45359.237 kilograms). Of this 10 tons if the atomic engine, 30 tons is the titanium structure of the spacecraft itself and the remaining 10 tons is for crew, cargo and equipment. The Luna also carries 200 tons (400000 pounds, 181436.948 kilograms) of propellent in the form of ordinary tap water.
Specific details about the atomic engine are difficult to come by. Whether it uses uranium, plutonium or some other radioactive fuel has not been released. We do known that it is a solid core nuclear thermal rocket (NTR) using water as it’s propellent giving it a exhaust velocity of approximately 13132.36 feet/second (4000 meters/second) and a specific impulse of 412 seconds.
At launch the rocket accelerated at approximately 5 gravities to achieve a altitude of 800 miles (1287.5 kilometers) after a initial 4 minute rocket burn.
46 hours after launch, the Luna lands on the Moon.
Although a impressive example of mid 20th century technology, the Luna was designed in a crash program to produce a prototype moon rocket as quickly as possible. As a result it incorporates certain design flaws.
First, the rocket does not use any form of staging. It is a single stage to moon and back rocket which has to carry it’s entire 50 tons of dry mass to the moon and back. Because of this and the difficulty in finding a smooth landing site, the crew was forced to scramble in a frantic effort to lighten the rocket sufficiently to be able to take off and return to the Earth. If, for example, some of the empty propellant tanks has been designed to be removable instead of fixed into the structure of the rocket, the overwrought drama of having to leave a man behind could have been easily avoided in it’s entirely.
Second, because the rocket is a radioactive ATOMIC rocket spitting out filthy protons and neutron in dangerous quantities, the crew cabin was placed as far of the engine as possible. As a result, the only means to reach the surface of the Moon is via a very long 75 feet (25 meters) ladder. Even in 1/6th gravity, that’s a heck of a long climb. A simple crane and wench arrangement would have eliminated the need of the ladder altogether as well as removing the extra weight of the mechanism to extend and retract the ladder rungs from the hull.
Third, despite having wings to glide through the atmosphere on the return to Earth the Luna was not designed to land on it’s belly like a aircraft. Based on initial notes by Robert Heinlein, the Luna should have made a powered decent onto it’s tail like God and Heinlein intended rockets to land. Instead, notes made during it’s development states the Luna makes it final decent on it’s tail by using parachutes contained in the nose of the rocket. Since the parachutes are already in place it should have been possible to eliminate the wings entirely. However since the wings could do double duty as radiators for the heat produced by the atomic engine another means of temperature control would have been required.
Regardless of these issues, the Luna has a well earned and beloved place in astronautical history.
In summary, here are the pertinent facts concerning the Luna
Length 150 Feet / 45.72 Meters
Width of Main Body 18.3 Feet / 5.578 Meters
Wing Span 69.36 Feet / 21.14 Meters
Dry Mass 50 Tons / 45359.237 Kilograms
Dry Volume Approximately 229.66 Cubic Feet / 70 Cubic Meters
Dry Volume Approximately 30% of total volume
Propellant Mass 200 Tons / 181436.948 Kilograms
Propellent Volume Approximately 590.55 Cubic Feet / 180 Cubic Meters
Propellent Volume Approximately 70% of total volume
Total Mass 250 Tons / 226796.185 Kilograms
Exhaust Velocity 13132.36 Feet per Second / 4000 Meters per Second
Specific Impulse 412 Seconds
Max Acceleration 5 Gravities / 160.87 Feet/Second^2 / 49.03 Meters/Second^2
Mass Ratio of 5