LTV XQM-93
A turboprop UAV developed for communications relay in Vietnam.
The LTV XQM-93 was a remotely piloted aircraft built for the United States in the late 1960s and early 1970s to serve as a communications relay during the Vietnam War. A prototype took flight in 1970, but the project ended before any aircraft entered service.
The effort grew out of earlier microwave high-altitude long-endurance studies. The U.S. Air Force partnered with LTV Electrosystems (later E-Systems) under the Compass Dwell program to create an unmanned aerial vehicle powered by a conventional turboprop engine. The work was partly inspired by the Igloo White program, a multiservice operation aimed at stopping supply movement along the Ho Chi Minh Trail through Cambodia and Laos. Igloo White involved dropping thousands of seismic and acoustic sensors that detected traffic and sent signals to a command center in Thailand, which then directed airstrikes. Because the sensors had limited battery life and range, airborne radio relay aircraft circled overhead to collect and forward the signals.
Initially, Lockheed EC-121 Warning Stars—military versions of the Super Constellation—handled the relay role, but they were expensive to operate. They were replaced by modified Beech Debonaire light aircraft, designated QU-22A, which could be flown as drones. In practice, however, they were never used without a pilot except in experiments.
LTV Electrosystems designed an endurance aircraft that could operate with or without a pilot. Several prototypes were built, both piloted and unpiloted. They were based on a heavily modified Schweizer SGS 2-32 sailplane, fitted with a Pratt & Whitney Canada PT6A-34 turboprop engine, large fuel tanks, and mission payloads. The landing gear was fixed tricycle type.
The first prototype, the L-450F, was piloted and first flew in February 1970. It was lost on its third flight in March 1970, though the pilot ejected safely. A second L-450F completed the flight test program. The third prototype, the first unmanned version, was designated XQM-93 and flew in early 1972. It had no cockpit or pilot provisions and could carry 320 kilograms (700 pounds) of payload. The Air Force ordered four XQM-93s, but it is unclear if any were delivered, as Compass Dwell was canceled that year.
Two airframes survive. One, N2450F (cn 002), is displayed at the Vintage Flying Museum at Fort Worth Meacham International Airport.
Quick Facts
- Aircraft Type
- Communications relay drone
- National Origin
- United States
- Manufacturer
- Ling-Temco-Vought
- First Flight
- February 1970
- Developed From
- LTV L450F
Facts from the source article.
Lore & Background
In the late 1960s, following early microwave HALE vehicle studies, the US Air Force worked with LTV Electrosystems under the Compass Dwell program to build an unmanned aerial vehicle using conventional turboprop propulsion. The effort was partly inspired by the Igloo White program, which seeded the Ho Chi Minh Trail region with seismic and acoustic sensors that reported to a central command center in Thailand via airborne radio relays. Initially, Lockheed EC-121 Warning Star aircraft served as relays, but they were expensive; they were replaced by modified Beech Debonaire QU-22A aircraft, which could be flown as drones but were never operated unpiloted in practice.
LTV Electrosystems developed an endurance aircraft that could be flown as a piloted aircraft or a UAV. Prototypes were based on a Schweizer SGS 2-32 sailplane with major modifications by Schweizer to accommodate a turboprop engine, large fuel tanks, and operational payloads. The first prototype, designated L-450F, was piloted and first flew in February 1970 but was lost on its third flight in March 1970; the pilot bailed out safely. A second L-450F completed the flight test program. The third prototype, the first UAV variant, was designated XQM-93 and flew in early 1972. It had no cockpit or provisions for piloted flight. The Air Force ordered four XQM-93s, but it is unclear if they were actually delivered, since Compass Dwell was cancelled that year.
Reader's Guide
The XQM-93 represents a transitional phase in UAV development, bridging early high-altitude long-endurance concepts with practical turboprop endurance aircraft. Its design, based on a Schweizer sailplane, emphasized endurance and payload capacity for the communications relay role demanded by the Igloo White sensor network. The program's cancellation before service entry highlights the challenges of operationalizing UAVs in that era, particularly the reluctance to trust unmanned flight for critical missions, as seen with the QU-22A. The XQM-93's legacy lies in its demonstration of a dedicated UAV airframe derived from a glider, and its surviving airframes serve as artifacts of a program that explored the potential of remotely piloted aircraft for persistent battlefield communications. The uncertainty over whether the four ordered XQM-93s were delivered underscores the program's abrupt end.
Did You Know?
- The XQM-93 was based on a Schweizer SGS 2-32 sailplane, heavily modified by Schweizer.
- The XQM-93 UAV variant had no cockpit or provisions for piloted flight.
- The Compass Dwell program was cancelled in 1972, and it is unclear if the four ordered XQM-93s were ever delivered.
More in Unmanned Aerial Vehicles by Country, Part 2 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced