The Need for Smooth

  • Published
  • By 46th Test Group
HOLLOMAN AFB, Nm --  The 846th Test Squadron is known worldwide for its ability to send test articles of all sizes down the Holloman High Speed Test Track (HHSTT) at record breaking speeds. Almost all of the test articles are simulating various regimes of flight, whether it is for a jet fighter ejection seat, guided missile launch, missile warhead against a target or even the flight of an artillery shell.

With an increase in speed comes an increase in the harshness of the ride down the rails. As the rocket powered sled goes very fast down the test track, its pushing forces are constantly fighting the restraining forces created by the sled's "slippers" which keep it hooked to the track rails, creating vibration. So, to go faster while simulating the smoothness of a flight test, a sophisticated engineering solution is needed - don't ride on rails, float above them! This technological leap requires magnetic levitation (MAGLEV), an idea currently used for high speed trains.

The HHSTT is developing a MAGLEV capability, but not because of the "need for speed," as explained by the HHSTT 846th Test Squadron commander, Lt Col Angela Suplisson. "We can put enough thrust behind just about any payload and get it going as fast as any customer would want." However, she agrees that speed is not the issue here, but rather vibration. Mr. David Minto, a former Track commander and current HHSTT technical director, further explained, "The MAGLEV concept allows us to study smaller, more sensitive objects, such as fuses, seekers, sensors, etc., in a flight-like environment. Instead of an extremely stiff steel-on-steel restraint system, the magnetic forces that restrain the sled are relatively soft." MAGLEV is smoother - like flying.

Just as the name implies, the sled is "levitated" magnetically and travels down a newly created track, this "new" track is nothing like a train rail but rather looks more like a slot car track from the 1960s. Sleds for this new track are suspended and guided by high-tech superconducting magnets chilled with liquid helium. These magnets have an incredibly strong magnetic field around them that interacts with the specially designed track to levitate the sled.

This MAGLEV track is made from special concrete that must be strong enough for a bridge yet contains no steel rebar for strength. The concrete recipe alone is an award winning high-tech design using non-magnetic stainless steel fibers for strength reinforcement. When steel rebar was used in laboratory tests, the standard steel rebar disrupted the magnetic activity needed to make a MAGLEV track possible.

While not yet as long as the traditional railed test track, the MAGLEV track is a work in progress and allows incremental testing of new components to improve sled performance and operational suitability. Speeds of over 350 mph have been achieved so far. Plans are in place to expand the facility to test at speeds over 2,200 mph or Mach 3 (three times the speed of sound). While people often think of the test track as the place to go fast, soon it will be where people can fulfill their need for "smooth" testing. That's why customers from all over the world continue to line up at the Holloman High Speed Test Track - to make sure they get their "smooth" data and are "on track toward the future."