German - U.S. VECTOR program concludes with world's first thrust-vectored automatic landings
24°Angle of Attack achieved in ESTOL mode
Patuxent River/Munich, 05 May 2003
The world’s first thrust-vectored automatic landing was the highlight of three years of joint testing between the partners U.S. Navy, the German Federal Office of Defense Technology and Procurement, EADS Military Aircraft and Boeing Aerospace from April 2000 to April 2003 within the VECTOR ‘ESTOL (Extremely Short Take-Off and Landing) to the ground’ phase. With German project test pilot Rüdiger Knöpfel at the controls and after thorough proofs of the technological functionality and simulated landings at safety altitude – the X-31 technology demonstrator performed this record-breaking maneuver on April 22 at Patuxent River Naval Air Station.
A week of intense test flying and 11 flights later, his U.S. counterpart, Marine Corps Major Cody Allee achieved the history-making final flight on April 29: an automated ‘ESTOL to the ground’ landing at 24° angle of attack and 121 knots landing speed, which is a 31 per cent reduction from the X-31 normal landing speed of 175 knots. Another big ESTOL advantage became evident for the spectators of this unique moment: Whilst the test aircraft normally requires 8,000 feet to stop after conventional landings, Allee needed after the ESTOL touch-down just 1,700 feet to slow the X-31 down for a complete taxiing circle in the middle of the runway. For the eye-witnesses, such a landing gave a real dramatic picture when the aircraft came in with its nose pointing well above its direction of flight. More importantly than the high angle of attack – up to twice its typical twelve degrees – was that the tail of the X-31 experimental aircraft was lower than the landing gear, requiring the aircraft to ‘de-rotate’ and drop onto its wheels when the thrust-vectoring vanes of the engine were just two feet above the runway. The two VECTOR project pilots, Rüdiger Knöpfel and Cody Allee described the ESTOL landing approach as “time-critical. If the aircraft derotates early and drops too far, the landing gear could fail”, Knöpfel said. ”If the aircraft derotates too late or too low, the tail could strike the runway with disastrous consequences.” The solution was to automate the entire landing approach, requiring the pilot to fly into an invisible engagement box in the sky, then watch via a video camera in the belly of the airplane as it flies itself to its remarkable touchdown with a system accuracy within two centimeters.
With this sensational success the VECTOR team reported the mission fully accomplished. Both program managers, Jennifer Young from the U.S. side and Michael Jost from EADS, were extremely satisfied with the results achieved. “I don’t know how many times we heard that the ESTOL technique just couldn’t be done”, said Young. “The cards were stacked against us for so long, and it was only the sheer determination and passion of everyone on the team that got us through.” Jost added: “At the beginning of the program, the technology was looked on very critically, because a lot of experts in Germany and the U.S. didn’t believe it was possible. It put great pressure on the team to prove that it works and to convince the non-believers.”
After completion of the ‘ESTOL to the ground’ flight tests within the given budget and timeframe, the program now enters the envisaged final leg of data analysis and reporting. This stage will ensure that the attained know how and technologies of thrust-vectored ESTOL can be used by the X-31 partners in Germany and the USA for future applications. One of the many potential ESTOL benefits for manned or unmanned air vehicles is the increase in the in-service lifetime of the airframes due to the reduction of the landing cycle impact. Others are the dramatically improved short-field performance on runways, roads or aircraft carriers, reduced wind-over-deck requirements for aircraft carrier operations, and increased bring-back weights without the current necessity to jettison external stores prior to landing.
In particular the German X-31 partners EADS and BWB will profit from the EADS-developed Flush Air Data System (FADS) for future military applications. FADS is a revolutionary miniature nose-mounted sensor which measures the local pressures deriving from airspeed, altitude, sideslip and angle of attack. Thanks to its technical features and the proven reliability and accuracy during the ESTOL to the ground test phase, FADS is able to replace the contemporary pitot/vane measurement devices for military aircraft and other air vehicles. One of the great FADS advantages for airborne military platforms lies in a significant reduction of the radar signature, compared to conventional systems.
Your contact:
EADS Military Aircraft
Wolfram Wolff
Tel: +49 (0)89 607-25711
Fax: +49 (0)89 607-22455
E-mail: wolfram.wolff@m.eads.net
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