Thursday, April 12, 2012

Digital Space Art by Terry Sunday

"In the 1970’s, the Martin Marietta Corporation (now Lockheed Martin) in Orlando, Florida, built what is still today one of the most incredible guided missiles ever to fly. The Sprint was a part of the only anti-ballistic missile (ABM) system that the United States ever deployed. Complementing the long-range Spartan interceptor, which was intended to destroy incoming nuclear warheads before they re-entered the atmosphere, Sprint was a short-range screamer with literally split-second reactions. It could intercept any warheads that got past Spartan when they were only seconds from their targets. Ejected from an underground silo by a hot gas generator, the two-stage Sprint accelerated so fast that it would pass a .50-calibre bullet, if fired at the same time, within a second. Atmospheric friction made the outside skin of the second stage hotter than the inside of the rocket motor. It was protected by a thick ablative layer that actually boiled away, carrying the heat with it. Sprint was tested successfully many times at White Sands Missile Range, New Mexico and at the Kwajalein Missile Range in the Pacific. It was beyond-state-of-the-art technology for its day.

This image shows Sprint in its silo. The missile sits on the eject piston, which in turn rests on a ring of springs to cushion the missile from ground shocks. When the gas generator under the piston fires, the piston shoots up the launch tube (stopping when it hits the piston arrestors at the tube mouth) and the Sprint continues out of the cell, literally blasting through the frangible fiberglass, foam and rubber domed cell closure. Tan “wedges” at the missile’s midsection near the second stage fins guide it out the tube. The cutaway shroud near the top of the missile is the “foam sock,” an insulating blanket around the guidance section and warhead that keeps the components at operating temperature at all times."

This is a repost from 2008, but I just got an email from this artist and wanted to share more of his work. Terry Sunday creates incredible artwork based on aerospace vehicles, some real, others hypothetical. This sprint image is probably the most accurate and detailed one available. In my initial post, I wondered about the lenticular covering, and if it served some mechanical or EM protective purposes. It turns out that this was a frangible cover that the rocket would break through, and that there was indeed EM shielding built into the cover by way of a wire mesh in the fiberglass, creating a faraday cage of sorts.

He elaborates further: "The 'double walled, lenticular cover' that you devote a lot of your comment to was a two-part cell closure. The inner part was the actual silo environmental and electromagnetic cover. It was made of fiberglass and wire mesh (for electromagnetic pulse attenuation), and was crisscrossed with an array of FLSC (Flexible Linear Shaped Charge), arranged in a modified 'X' pattern aligned with the missile’s fins. At a specific time in the launch sequence, the FLSC exploded and cut the inner closure into pieces as the Sprint accelerated through it. The outer part of the closure was called the 'foam dome,' and it was made of rigid foam something like Styrofoam. Its purpose was not to protect the silo against the overpressure of a nearby nuclear burst—it was not nearly strong enough for that—but to protect it from the thermal pulse. It was painted white and had a thin layer of rubber bonded to the outside of it, as I recall, that would reflect much of the thermal energy of a nuclear detonation. Essentially, it 'ablated' to carry away the heat, similar to the phenolic-resin coating on the outside of the missile’s second stage. Each bolt head that attached the closure to the lip of the silo was similarly protected by a white rubber cap for the same reason. Since the 'foam dome' had very little structural strength, the missile simply flew right through it. There was nothing but air between the two parts of the closure, and it had nothing to do with 'radiation shielding.'"

There are many other images in the gallery, including this neat RV with lots of physics package details within. These details are hypothetical.

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