GQM-93 / E-system L-450 / Compass Dwell
The E-Systems L-450 is a multi-mission, single-engine, high-altitude, long-endurance aircraft. This aircraft can be operated as either a manned aircraft or a remotely piloted vehicle (RPV). The L-450, which would be designated the XQM-93A by the military, was a high-altitude turbo-prop that could be flown either by a pilot or by remote control. L-450F is the designation for the Ling-Temco-Vought piloted version, and the military UAV designation is XQM-93A. The L450F aircraft was based on the Schweizer SGS 2-32 sailplane, and was first flown in manned configuration in February 1970. A 1971 Air Force contract had E-Systems developing and producing a military version of its L-450 aircraft.
The HALE RPV (High-Altitude, Long Endurance, Remotely Piloted Vehicle) development was undertaken by the Aeronautical Systems Division to satisfy that trend toward unmanned airborne relay aircraft for reasons of cost effectiveness, reduced crew vulnerability, increased station-keeping time, etc. Aircraft built under the HALE program were expected to fly at altitudes as high as 50,000 ft (15+ km) for up to 24 hours.
Although the RPV's were considered backup relay platforms, their inherent flexibility gave them advantages in their own right. Unlike conventional satellites, which require months of preparation and planning prior to being placed on station, RPV's generally can be on location within minutos or hours of the decision to launch. There are other advantages also: lower costs, less sophistication in design since the equipment does not have to be space-qualified, reduced vulnerability to jamming, and the ability to implement relay equipment changes quickly if battle requirements so dictate.
Two different classes of RPV were evaluated for the HALE RPV role. One, the XQM-93A model, manufactured by E-Systems, Incorporated, was identified by the 478T Program Office as the aircraft to be used in the TRI-TAC Service Test Bed at Fort Huachuca, Arizona in 1977, when a system operational test and evaluation program would be carried out. The other class of RPV consists of the YQM-94A and YQM-98A models developed by Boeing and Teledyne Ryan under the Compass Cope program.
The aircraft can fly slowly in circles at altitudes between 13.7 to 168 km (45,000 to 55,000 feet) for 24 hours. The L-450 payload capacity is 26 cubic feet. About 20 cubic feet is available as one continuous bay aft of the cockpit, and an additional 6 cubic feet is available in a narrow area off the primary 20 cubic foot payload bay. For L-450F, the RPV version, the cockpit provides another 18 cubit feet for payload. The total payload space is 44 cubic feet, and the total payload capacity is 1100 pounds. Electric power available is 6 kW at 28 volts.
The L-450 is powered by a PT-6A turboprop engine manufactured by United Aircraft of Canada, Ltd. This engine now has over 10 million flying hours, and it has been installed in 2,000 operational aircraft. The engine experienced an in-flight shutdown rate of 1 per 100,000 hours operating time. The time between overhaul is up to 7,000 hours.
The XQM-93A was quite a bit smaller than the Compass Cope aircraft: 4600-lb (2087 kg) launch wt, 29-ft (8.84 m) length, 57-ft (17.37 m) span vs 14,400 lb (6532 kg). 41ft (12.5im) and 90 ft (27.43 m) respectively. Its design service ceiling is also less: 45,000-52,000 ft (13. 72-15. 85 km) vs 50- 70,000 ft (15.24- 21.34 kin) for the Compass Cope aircraft. The XQM-93A did have the advantage of having flown at its design altitude, however, for the required 24 hours.
The "roadmap" for the 478T system development shows that LTA platforms, if available, will also be evaluated in the 1977 tests. This inclusion of balloon systems implies, correctly, that the RPV platforms were not without disadvantages.
Perhaps the major disadvantage to a high-altitude RPV (Compass Cope) is its limited TRI-TAC (or tri-service tactical) utility because of its long wing span (-90 ft, 27.4 m). The physical problems associated with handling an aircraft of that size, plus the need for a 2000-ft (610 m) take-off run, create obvious difficulties for Navy personnel trying to launch from a ship at sea or for Army personnel operating in rough field locations. The smaller XQM-93A RPV, which appeared to be an interim selection, is easier to handle, of course, but if the stated goals of the multi-mode system are realistic, that is, relay operations at an altitude of 60 - 90, 000 ft (18.29-24.38 kin), operational planning should be in terms of the larger aircraft.
Another major disadvantage of the HALE RPV is its fairly short flight endurance time, approximately 24 hours. This characteristic demands daily launching and recovery operations to insure continuous availability of a relay on station. In a battle situation, or under prolonged bad weather conditions, such a frequency might prove to bc operationally impossible. Even in the best of circumstances, the daily operation would be less desirable and less cost effective than one carried out less frequently. Other constraints associated with the HALE RPV include its payload weight, ~750 lb (340.2 kg) and payload volume, 44 ft 3 (1.25 m3 ). Although those figures appear to be quite reasonable for the intended mission, they left very little room for growth or for outsized payload configurations. Also, the service ceiling of the XQM-93A RPV, 52,000 ft (15.8 km) was comparatively low and, thus, inhibited line-of-sight transmission possibilities.
The E-Systems L-450 turbo-prop aircraft that the company had designed in the '70s participated in air shows in Europe in 1984, helping to spark new interest in a high-altitude aircraft. This would lead to the development of a new aircraft with aircraft manufacturer Grob and enginemaker Garrett Aviation, which was eventually called the EGRETT (a contraction of E-Systems, Grob and Garrett). The new EGRETT aircraft development would be announced in 1986 as a multi-purpose, allcomposite, turboprop with a broad spectrum of capabilities for both commercial and military markets. The first flight of the EGRETT proof-of-concept was accomplished in early 1987. The aircraft would eventually set several world records for turboprops in its class for altitude and endurance.
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