Problems with Problems With The Orion Spacecraft #9: Stress

Myth:
The ship's structure itself ... has to be able to take the stress of sitting next to a bunch of exploding nuclear bombs. Even with shock absorbers, it would be under repeated stress of a type not experienced by any vehicle we have ever built. The ability of a battleship to survive the strain of firing its own guns was the subject of a considerable amount of development efforts in the early 20th century, and that strain would be dramatically less than the strain experienced by an Orion. -POS


----
Fact:

"Both the pulse frequency and the acceleration profile are reasonably well simulated by a child's backyard swing operating through an arc 65deg each way from vertical". GA-5009 Volume 1 Page 14
Quoted in Project Orion Page 179


-------------

Index of problems with POS

Radiation shielding in General Atomic's 10 and 20 meter Orion designs

From GA 5009 Volume 3

"Most missions for the 10-m configuration require less than 3,000 pulses,
so a bottom shielding requirement of 1Z0 g/cm^2 of hydrogenous material
was used for most conceptual designs.
Shielding of Z5 g/cm^2 or more was thus provided on all sides of
the powered flight station. According to recent studies of planetary
exploration requirements, this shielding is sufficient to attenuate the
probable solar-flare radiation to dose values similar to the 50 rein
allowed for propulsion. the total mission dose from both sources
was expected to be about 100 rem".

Dynamic America

Dynamic America by General Dynamics and Doubleday published 1960

"Within this decade chemical propellants will reach their highest point of efficiency. But even this power increment will not be sufficient to develop spaceflight capability beyound a bare minimum. Nuclear powe seems most likely to provide the energy-weight ratio requisite to lift megatons into deep space. Theoretically feasible, such systems are under intense study at General Atomic Division (Project Orion) and elsewhere."

Orion designs compared to launch fireballs #2

Here's the 571,000 ton Orion at 5 x plate radius above the 20kt fireball 1/2 second after detonation.



Index and Fireball images#1

Orion designs compared to launch fireballs #1

We can calculate the proper scale for the 20 kt fireball images available here.

Using the chart on page 55 of Project Orion we can figure the gross takeoff mass, 571,000 tons.

Borrowing one of Selden's drawings we can combine these two images.

This covers the inital fireball,
#2 .5 seconds
#3 1.25 seconds

Orion ISP at low altitude

In this post calculations based on page 55 of Project Orion show that the orbital test vehicle's low altitude pulse units average size is 108 pounds. The 664 lb vacuum pulse units have an ISP ranging from 3000-6000, but the chart has no ISP data for the smaller units. We can calculate the implied ISP which will vary with cycle rate, at .8 seconds per pulse the result is 15,800 seconds.