The Garrett

The Garrett, Linear Induction Motor Research Vehicle (LIMRV) – world record holder

“Rocket Train”

Garrett AiResearch (pronounced “air-research”) designed and built the LIMRV (Linear Induction Motor Research Vehicle), an aluminum clad high speed test vehicle. As the name implies, this vehicle was built specifically to test the capabilities of the Linear Induction Motor. The 56 foot, 27 ton vehicle has high-speed passenger train wheels to run on standard railroad tracks – at 250 mph. The vehicle ran on electric power, which on other types of engines is usually obtained from either overhead catenary wires, or a “third rail” underneath the train. But the projected speed of the Garrett LIMRV was simply too fast to use either of those methods for power collection. The electricity for this engine had to be carried “on-board”. A surplus 3000 hp aircraft gas turbine from a crashed NASA plane was fitted to supply the LIMRV with electricity.

A High Precision Track

Low-speed testing was performed initially on a quarter-mile track at the Garrett plant to ensure there were no major design issues. The LIMRV was delivered to the High Speed Ground Test Center in early 1971, and testing began in May, as part of the Test Center’s “grand opening”. Calculations showed that the test track at the Test Center needed to be 10 miles long to achieve the design speed. But there was only enough DOT funding to build 6.2 miles of track, because the track was special in a couple of different ways. There was of course the 21-inch-high reaction rail protruding up from the middle of the track. Apart from that, this test track looked just like any other railroad track – rail on top of railroad ties (closer together than usual), with crushed stone ballast underneath. But because of the very high speeds involved, the construction tolerances and “control of geometry” make this test track more precise than any track ever built up to that time.

A view of the high-precision rails for the Garrett

Testing of the Garrett

Tests on the Garrett at the Test Center could be either manned or unmanned. The Test Center had a trailer outfitted with remote control equipment. The Garrett was manned only for tests where the expected speed was under 100 mph. For speeds beyond that, remote control was used.

Temperatures of -16°F in late 1971 caused damage to the reaction rail, restricting tests to low speeds on a small section. But by February 1972, the reaction rail was repaired and high-speed testing had resumed.

Slideshow: Photos from the National Archives of Garrett LIMRV test runs in March 1973

The Need For Speed

Beginning in the Fall of 1973, the Garrett was equipped – for certain tests – with two Air Force missile program surplus jet engines. They were added as “thrust boosters” to get the vehicle up to speed quickly on the limited 6.2 mile length of its test track. Adding these Pratt & Whitney J52-P3 jet engines was actually cheaper than extending the test track to the full 10 miles. On August 14, 1974, this Garrett LIMRV prototype set the world speed record for air-powered “wheel-on-rail” vehicles at 255.6 mph, a record that still stands today. Other electric-powered vehicles have since gone faster, but as of today, the Garrett is still the fastest gas turbine powered vehicle on rails. Having achieved its designed speed, engineers turned their focus to fine tuning the operational characteristics of the Garrett – braking, noise, motor edge effects, etc. The Garrett testing program was completed at the TTC in 1978, after which the vehicle was donated to the Pueblo Aircraft Museum.

Slideshow: The Garrett at the Pueblo Weisbrod Aircraft Museum

When the time came in 2008 for the Pueblo Aircraft Museum to build its new hanger to house its WWII planes, the Garrett was actually “out of town”. It had been on loan for several years to an organization in New Castle, PA for a research study, and was therefore out of the way of the heavy equipment that would build the Aircraft Museum’s new exhibit hanger. The Garrett returned to Pueblo, the last place where it had operated under its own power, on October 24, 2012. Early the next morning, in very chilly conditions with a dusting of snow, two cranes unloaded the Garrett onto the tracks behind the Pueblo Railway Museum shop.

Slideshow: The Garrett is moved from the Aircraft Museum to the Pueblo Railway Museum, October 24-25, 2012
Slideshow: Museum volunteers build a track in the shop and move the Garrett indoors, October 31, 2012
Slideshow: The Garrett is moved to its current location in front of the Pueblo Railway Museum shop, April 2, 2019

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