Joy Turns To Sorrow
Carter Aviation Technologies announced they unofficially broke
the Mu-1 barrier in flight-testing Friday morning. This historic
first is expected to be verified over the next few weeks.
Unfortunately, the aircraft suffered a hard landing in an afternoon
flight test, causing extensive damage to the airframe. The crew
escaped without injuries.
The CarterCopter broke the Mu-1 Barrier at 0740 Friday, June
17th, 2005. The flight test began at the Olney Airport in Texas.
This is the first time in history that any rotorcraft has exceeded
The barrier was breeched during normal flight-testing while
collecting data on a newly developed speed controller for the
rotor. The milestone attempt was not planned but evolved as
flight-testing proved the rotor to be very stable as the rpm was
decreased. Test pilot, Larry Neal, was decreasing rotor rpm in
small increments when he neared Mu-1.
With all systems stable the decision was made to proceed above
Mu-1. Initial data from the flight shows that the airspeed was 170
mph and the rotor was slowed to 107 rpm giving a value of 1.02.
Previously, the lowest rotor speed achieved was 115 rpm. The higher
than Mu-1 flight time was just 1.5 seconds before Neal reduced the
throttle to slow the aircraft, but the flight was accomplished
Mu is the ratio of the forward speed of an aircraft to the tip
speed of its rotor. Normal helicopters fly at a Mu of approximately
0.3, meaning that the rotor tip speed is roughly three times
greater than the forward speed of the aircraft. At a Mu of 1 the
forward speed of the aircraft and the tip speed of the retreating
blade are equal. The retreating blade has an air velocity at the
tip of zero with reversed airflow over the entire length of the
blade. At this point, the retreating blade can provide very little
lift and becomes very unstable.
The significance of high Mu flight has long been understood but
the design of conventional rotorcraft made it impossible. Carter's
design is definitely unconventional and includes 16 patented
technologies. The company claims Carter technology should allow
flight speeds up to a ratio of Mu-5 (where the aircraft is
traveling at speeds up to 500 mph and the tip speed of the
advancing rotor blade remains under mach 0.9).
The CarterCopter is the prototype aircraft of Carter Aviation
Technologies (Carter). The prototype is the technology demonstrator
of Carter's Slowed Rotor/Compound (SR/C) Aircraft Technology and
has been in flight-testing since 1998. Today's historic flight
culminates more than 12 years of research and development and
continues to validate Carter's revolutionary technology.
Jay Carter, Jr., Carter's President and Chief Development
Engineer, was nearly speechless as the data reports came in from
the flight. The milestone has eluded Carter for more than three
years after achieving a flight of Mu-.87 in 2002. According to Jay
Carter, "This (breaking Mu-1) has been our goal since we first
began flight-testing in 1998. To prove our technology we needed to
do something that no one else had ever done. We have had several
setbacks, but no one on the team has ever lost faith. This is
Carter's flight data has proven to be very accurate in the past,
however, as an element of a current U.S. Army contract the Army is
scheduled to verify the calibration and accuracy of Carter's data
retrieval system in the next few weeks. This corroboration will
provide a more official determination of this milestone flight.
Until then, the Carter team will anxiously wait to secure its place
as having achieved one of the most significant milestones in
The good feelings left before sundown. On an afternoon flight
test around 1600, the CarterCopter reported mechanical problems and
came in for an emergency landing. The aircraft descended at an
above average speed until it contacted the ground. Fortunately for
the crew, the landing gear was down and absorbed enough of the
impact to protect the pilot and co-pilot. Initial reports are that
the CarterCopter sustained extensive damage and is not repairable.
More details should be released early next week. Stay tuned.