The British Invasion: CHIRP and HIRM Support the Tornado

In 1981, researchers at NASA Dryden assisted with the first of several series of tests for the British Royal Aircraft Establishment (RAE) under an international agreement to collect data relevant to the Panavia Tornado jet fighter, a large-scale NATO acquisition program. The variable-wing- sweep Tornado eventually became a major deep-strike attack aircraft used by the British, then-West German, and Italian air forces. Britain’s Royal Air Force flew an interceptor variant as well. During the 6-week Cooperative High Incidence Research Program (CHIRP), 4 25-percent – scale Tornado models of varying configurations were used to conduct 10 drop tests. Six of these flights were undertaken to gather unaugmented stability and control data to improve RAE engineers’ mathematical model of Tornado aerodynamics. The remaining 4 drops (totaling 130 seconds of flight time) were allocated to evaluating a Spin Prevention and Incidence-Limiting System (SPILS) in support of a modification program for the full-scale operational Tornado fleet.

In February and March 1981, NASA and RAE officials met to discuss support requirements for the project. Once details had been decided, Walter B. Olstad of NASA’s Office of Aeronautics and Space Technology and R. J.E. Glenny of the British RAE signed a Memorandum of Agreement. The first Tornado model arrived at Dryden in a British Royal Air Force C-130 transport May 11. Edward "Ted” Jeffries and Owen Forder of the RAE arrived a week later to assemble the model and install NASA telemetry equipment. Three more Tornado models arrived at the end of July.[966] The quarter-scale models were constructed of fiberglass, wood, and metal. Each was equipped with a rudder and an all-moving tailplane with differential deflection. Instrumentation included transducers, telemetry, servo systems, and radar transponder equipment. To reduce complexity and cost, the models were not equipped with landing gear. Instead, recovery parachutes were provided to allow for a soft landing in the desert. Each model weighed approximately 661 pounds and was towed aloft beneath a helicopter, using a 98-foot cable with an electromechanical release system. A small drogue chute stabilized the model prior to drop in order to maintain proper heading, and it separated at launch. An onboard, preprogrammed controller actuated the model’s control surfaces. From a launch altitude of 11,900 feet, each model had a maximum gliding range of about 4.7 miles.[967] The British team, consisting of Jeffries, Forder, Charles O’Leary, Geraldine F. Edwards, and Jim Taylor, had the first model ready for flight by August 25. Dubbed ADV-B—reflecting its shape, which was that of the so-called long-nose Air Defense Variant (ADV) of the Tornado design— the model was carried aloft August 31 beneath a UH-1H on loan from NASA Ames Research Center. The helicopter was piloted by Army Maj. Ron Carpenter and NASA research pilot Donald L. Mallick, with O’Leary as observer. Following release from its tow cable, the Tornado model glided to a landing on the Precision Impact Range Area, east of Rogers Dry Lake.

Tornado model ADV-C was dropped the next day, and ADV-D followed with a test on September 3. Five days later, the fourth model—called IDS-I for Interdiction Strike configuration (the snub-nose surface attack variant of the Tornado)—was successfully dropped over the PIRA. By September 22, the ADV-B and ADV-D models had each flown three more times.[968] Although three of the models were unserviceable at the completion of the tests because of damage sustained during recovery, CHIRP constituted an outstanding success. Previous flights had been made at test ranges near Larkhill, U. K., and Woomera, Australia, but with less impressive results, so much less so that the data acquired during testing at Dryden was equiv­alent to that collected during 5 years of earlier tests at other locations.

A second test series involving the three Tornado variants previously flown, along with two High-Incidence Research Model (HIRM) vehicles, took place in 1983. The HIRM shape included a boxy fuselage, conven­tional tail configuration, and close-coupled canards in front of the wings. On July 6, the first of two HIRM models flew once at Larkhill to test all systems and basic aerodynamics.

Following arrival of the test team at Dryden, the first model was ready for flight by September 23, but the mission was canceled because of adverse weather. ADV-D was successfully dropped 4 days later. The following day, the IDS-I model was flown but was damaged during land­ing and did not fly again. Two more flights each were made with the ADV-D and ADV-B models in October.[969] The remaining sorties were flown using the two HIRM models, dubbed "Hirmon” and "Hermes.” Unlike the Tornado models, these did not resemble an operational air­craft type. Rather, they represented an entirely new research aircraft configuration. The HIRM models were equipped with an active control system capable of maintaining bank angles below 30 degrees.

The first drop of Hirmon at Dryden was terminated after just 22 sec­onds of flight, when an overspeed sensor triggered the vehicle’s parachute recovery system. Hermes flew several days later, but the mission was termi­nated immediately after launch because of failure of a barometric switch in the recovery system. Successful flights of both HIRM vehicles com­menced October 14 and continued through the end of the month, when the test models were packed for shipping back to the United Kingdom.

Of the 20 flights scheduled at Dryden during a 6-week period, 5 were eventually canceled. Fifteen flights were completed successfully. The British team worked punishing 12-hour days and 6-day weeks to sustain the flight rate. Three models remained flyable at the conclusion of the project. One Tornado sustained repairable fuselage damage requiring an alignment fixture not available at Dryden, and a second Tornado sustained minor but extensive damage as the result of being dragged through a small tree after a successful parachute landing. The HIRM models were used in 10 of the flights in this series.[970] A third test series was conducted in 1986 under a joint agreement among NASA, the U. S. Department of Defense, and the British Ministry of Defence. A four-person test team traveled from the U. K. and was joined by five Ames-Dryden project team members who provided management and support-services coordination. The Air Force Flight Test Center and U. S. Army Aviation Engineering Flight Activity group at Edwards provided additional support. Typically, an Army UH-1H heli­copter carried the test model to an altitude of between 10,000 to 11,500 feet and released it over the PIRA at 72 to 78 knots indicated airspeed.

Three Tornado and the two HIRM models arrived at Dryden in October. Hirmon and Hermes were flown 12 times, logging a total of 24.48 minutes of flight time. The Tornado models were not used, and

Hermes flew only once. Two flights resulted in no useful data. Five were canceled because of adverse weather, four because of helicopter unavail­ability, and five more because of range unavailability. Manual recovery had to be initiated during the third drop test. Both models survived the test series with minimal damage.[971]