Missiles, missile, rvx 1-5, tektites, Smithsonian, re-entry, recovered, australite, icbm

Missiles

If you are interested in tektites then you might also have a healthy interest in inter-continental ballistic missiles! Missile research and early tektite research went hand-in-hand. I am fascinated by the materials missiles use and their aerodynamics. I recently acquired these original press release photos of the flown RVX 1-5 re-entry vehicle. It flew to 764 miles in altitude and reached Mach 20 during re-entry. The ablative heat shield was an AVCO manufactured fused opaque quartz. Here is what the Smithsonian National Air and Space Museum, who own the missile, have to say:

This is the flown RVX 1-5 reentry vehicle, built by General Electric for the U.S. Air Force and the first reentry vehicle recovered by the United States after an intercontinental-range flight. Launched on 8 April 1959 atop a Thor-Able rocket from Cape Canaveral, it was recovered in the South Atlantic after a down-range flight of 10,180 km (6,325 miles), during which it reached temperatures above 12,000 F. Instruments within the RVX 1-5 and the nose cap, which was protected by special Avcoite heat-shielding material, provided valuable scientific data to the Air Force. The nose cap at the tip of the vehicle is a mock-up, as the flown one was removed for testing and was acquired separately by NASM in 1963. This RVX 1-5 was donated by the Air Force in 1960.

Here is an extract of the book 'Titan II: a history of a cold war missile program' by David K. Stumpf: In December 1957, General Electric Company's Missile and Space Vehicle Department began participation in a three-part flight program, sponsored by the Air Force, to evaluate ablative materials for use in reentry vehicles: Thor-Able phase I; Thor-Able phase II (RVX-1); and Atlas (RVX-2). Thor-Able Phase I reentry vehicles were not recovered, while both the RVX-1 and RVX-2 reentry vehicles were recovered. Thor-Able Phase I demonstrated the successful reentry of an ablation-type reentry vehicle at ICBM ranges and velocities. Using a Thor IRBM for the first stage and the second stage of Vanguard, the "Able" flight vehicle was a biconic-sphere, approximately three feet long and two feet in diameter at the base, and weighing 600 pounds. Two successful flights proved the feasibility of ablative material-based reentry vehicles and paved the way for Thor-Able Phase II, which used the RVX-1 reentry vehicle configuration.

The RVX-1, a flared-cylinder, conic-sphere design, had a maximum diameter of 2.5 feet and was approximately 5 feet long, weighing 700 pounds. A variety of ablative materials, those of both General Electric and AVCO, a second company involved in reentry vehicle design at the time, were flight tested using the RVX-1 shape. While still using the Thor-Able booster configuration, this program differed from the Phase I program in that the β for the reentry vehicle was significantly higher. Four of the six flights had successful test trajectories. Two flights, one for the AVCO product and one for the General Electric product, ended with the recovery of the vehicles for inspection and evaluation. The results from the RVX-1 series led to the development of the General Electric Mark 3, the first ablative reentry vehicle used at intercontinental ranges, deployed on Atlas D.

Here is an extract of the book 'Facing the Heat Barrier: A History of Hypersonics' by T. A. Heppenheimer: A new series of tests went forward during 1959, as General Electric introduced the RXV-1 vehicle. Weighing 645 pounds, 67 inches long with a diameter at the base of 28 inches, it was a cylinder with a very blunt nose and a conical afterbody for stability. A flight in March used phenolic nylon as the ablator. This was a phenolic resin containing randomly oriented one-inch-square pieces of nylon cloth. Light weight was its strong suit; with a density as low as 72 pounds per cubic foot, it was only slightly denser than water. It also was highly effective as insulation. Following flight to full range, telemetered data showed that a layer only a quarter inch thick could limit the temperature rise on the aft body, which was strongly heated, to less than 200 deg F. This was well within the permissible range for aluminium, the most familiar of aeriospace materials. For the nose cap, where the heating was the strongest, GE (General Electric) installed a thick coating of molded phenolic nylon.

Within this new series of flights, new guidance promised enhanced accuracy and a better chance of retrieval. Still, that March flight was not recovered, with another shot also flying successfully but again sinking beneath the waves. When the first recovery took place, it resulted largely from luck.

Early in April an RVX-1 made a flawless flight, soaring to 764 miles in altitude and sailing downrange to 4,944 miles. Peak speed during re-entry was Mach 20 or 21,400 feet per second. Peak heating occurred at Mach 16, or 15,000 feet per second, and at 60,000 feet. The nose cone took this in stride, but searchers failed to detect its radio signals. An Avco man in one of the search planes saved the situation by spotting its dye marker. Aircraft then orbited the position for three hours until a recovery vessel arrived and picked it up.

It was the first vehicle to fly intercontinental ranges and return for inspection. Avco had specified its design, using an ablative heat shield of fused opaque quartz. Inspection of the ablated surface permitted comparison with theory, and the results were described as giving "excellent agreement". The observed value of maximum ablated thickness was 9 percent higher than the theoretical value. The weight loss of ablated material agreed within 20 percent, while the fraction of ablated material that vaporized during re-entry was only 3 percent higher than the theoretical value. Most of the differences could be explained by the effect of impurities on the viscosity of opaque quartz.

A second complete success was achieved six weeks later, again with a range of 5,000 miles. Observers aboard a C-54 search aircraft witnessed the re-entry, acquired the radio beacon, and then guided a recovery ship to the site. This time the nose-cone design came from GE.  

Ultimately the General Electric Phenolic Nylon was used in subsequent designs, primarily because it was lightweight. Nonetheless I am grateful for the Avco fused opaque quartz test nose-cones due to the similarity to tektitic material!

 

ABOVE: News article dated April 23, 1959. NOSE CONE RECOVERED. It was found off Ascension Island in South Atlantic. Inflated bag kept it afloat.  Text on photo: (NY7-April 22) RESCUE ON THE HIGH SEAS--The nose cone of a Thor-Able missile, first to be recovered after a 5,000-mile trip in space and re-entry into the earth's atmosphere, is lifted from the South Atlantic waters near Ascension island following the recent firing from Florida's Cape Canaveral missile range. The inflated bag on the surface, still attached to the nose cone by ropes, kept the missile nose from sinking until the Air Force ocean range vessel Coastal Crusader located the prize. (U.S. Air Force Photo via APWirephoto) (jdc50845usaf) 1959. 

ABOVE: Stamped Oct 1960. Text on photo: WAP-101801-10/18/60-WASHINGTON: The Air Force 10/18 presented to the Smithsonian Institution's Natl Air Museum the RVX 1-5, the first re-entry nose cone which was fished from the South Atlantic 4/8/59 after a Thor-Able rocket boosted it on a flight of more than 6,325 miles from Cape Canaveral. Lt. Gen. Bernard A. Schriever (left) of the Air Research & Development Command and A. Remington Kellogg, asst. secy of Smithsonian are shown with the cone following the presentation ceremonies. UPI [United Press International] TELEPHOTO grg.

ABOVE: News article dated May 15, 1959: RECOVERED NOSE CONE DISPLAYED PUBLICLY. Lt. Gen. Bernard Schriever, commander of the Air Research and Development Command, and K. R. Wilson Jr., AVCO Mfg. president, inspect the nose cone. Second news article dated Aug 5, 1959: FORERUNNER OF TITAN CONE. lt. Gen. Bernard Schriever, chief of the Air Research and Development Command, and Kendrick Wilson (left), president of the Avco Corp., inspect nose cone that was recovered from the South Atlantic April 8 after test flight from Thor Able missile. The cone is being developed for use on the Denver-built Titan missile.

ABOVE: An enlarged portion of the above photograph.

 

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ABOVE: A couple of Australites which were ejected around 6,000 km from the point of impact. Note how the flow becomes turbulent towards the edges. Now compare these and other Australite images with the RVX 1-5 missile nose cone above. On really fresh Australites one can even see flow lines like those seen on the frontal part of the missile nose cone.

ABOVE: A perfect Australite from Port Campbell (O'Keefe J. A., 1963).

 

ABOVE: Laboratory Nose Cones (O'Keefe J. A., 1963).

 

Some more reading:

Titan II: a history of a Cold War missile program by David K. Stumpf

The RVX 1-5 in the Smithsonian Air and Space Museum Collection

Facing the Heat Barrie: A History of Hypersonics by T. A. Heppenheimer