Going Up: Paul Shumpert Recognized for Pioneering Work in Vertical Flight
Paul Shumpert, a retired propulsion engineer who designed the thrust augmentation system on the Lockheed XV-4A Hummingbird research aircraft in the early 1960s, and is recognized as the co‑developer of the integrated lift fan propulsion system now employed on the Lockheed Martin F-35B multinational, multirole fighter, is the latest recipient of the prestigious F.E. Newbold V/STOL Award, presented by the American Institute of Aeronautics and Astronautics (AIAA) to recognize outstanding creative contributions to the advancement and realization of powered lift flight.
The Newbold Award is presented by AIAA approximately every three years. Shumpert, who spent his entire 35-year professional career with the then-Lockheed-Georgia Company in Marietta, Georgia, and the then-Lockheed Advanced Development Projects (the Skunk Works) in Burbank, California, before becoming a consultant for an additional 14 years to Lockheed Martin, is the fifthteenth recipient of the Newbold Award.
Shumpert was cited by AIAA for his “four decades of service to advance the propulsion-enabling technologies for VTOL, STOL, and STOVL [vertical takeoff and landing, short takeoff and landing, and short takeoff/vertical landing] aircraft.” As Lockheed Martin Marietta Skunk Works senior manager Chuck Hybart noted, “To say he had an impact on this company would be an understatement.”
Let's Start From the Beginning
Shumpert began his career in 1956 after graduating from Clemson University. After a six-month leave of absence to serve in the U.S. Army as a mechanical engineer under a critical skills program, he returned to Lockheed-Georgia as a thermodynamics engineer. “I got interested in lift and ended up spending most of my career there,” Shumpert noted.
Lockheed, like most U.S. aircraft companies in the late 1950s, was investigating vertical flight, using both company independent research and development (IRAD) and small government contracts. A number of research aircraft, all using different methods—or combinations of methods—to produce vertical lift were built and tested through the 1960s.
Under research engineer Dr. Frank Sutton, Lockheed-Georgia Company, which went by the acronym GELAC, received a small contract from the Office of Naval Research in the late 1950s to investigate jet thrust augmentation—in simple terms, diverting the exhaust produced by a jet engine, mixing it with ambient air pulled into chambers above the engine through openings on the top of the aircraft fuselage, and then forcing the mixture downward out the bottom of the aircraft; thus producing more thrust than by the jet engine alone. The end result is vertical lift.
Research Becomes Reality
In July 1961, GELAC received a $1.2 million fixed price contract from the U.S. Army Transportation Research Command that called for design and construction of a thrust augmented demonstrator aircraft for ground and flight test. A contract addenda that September added $1 million for a second demonstrator.
Originally designated VZ-10, the aircraft became the XV-4A Hummingbird under the new tri-service designation system adopted by the Department of Defense in 1962.
The twin-engined XV-4A had a very small budget and was designed and built by a very small team—about 20 engineers, approximately 50 shop personnel, and one test pilot initially. Shumpert served as the project’s propulsion engineer. Some of the lessons learned from the previous company research found their way into the design of the thrust augmentation system. The reduced budget for the Hummingbird resulted in much of the propulsion testing normally done on a test rig being done on the actual aircraft.
On 29 June 1962, one year and one week after the program began, the first XV-4A was rolled out, only slightly behind schedule. Company Chief Test Pilot Leo Sullivan (who would make the first flight on six different aircraft in Marietta) made the first flight, taking off like a conventional aircraft, on 7 July from Dobbins AFB, adjacent to the GELAC facility. The initial flight tests of the aircraft in horizontal flight mode were successful.
“The design goal for the ejector thrust augmentation was 1.4 times the thrust of the engines,” Shumpert said. “With the initial augmenter configuration, the ratio ended up being only 1:1—no net increase in thrust. I had to tell my boss that we had a problem. I was a young engineer then and I really thought I was going to lose my job.
“We could only make minimal changes to the augmentation system without changing the aircraft’s outer mold lines. By changing the augmenter nozzle arms to a higher elliptical aspect ratio and smaller internal flow area upstream of the nozzle exits than the original, we got better results,” Shumpert continued. “However, this nozzle configuration failed after only about 20 minutes in test.”
After additional nozzle redesigns, the first changing from three to two round nozzles per arm, and second, from two round nozzles to a single slot nozzle per arm, we got the thrust augmentation to about 1.25,” recalled Shumpert. “We had to fly at reduced weight, but the aircraft was able to take off and land vertically.”
Company pilot Glen Gray made the first full transition flight—vertical takeoff, transition to horizontal flight, vertical landing—on 8 November 1963. Over the course of this phase of testing, issues with the XV-4A’s roll and pitch control and stability augmentation system (the XV-4A installed a boundary layer control feature as well on the horizontal tail) were also ironed out. Unlike today’s computer-controlled, fly-by-wire F-35, the systems on the Hummingbird were nearly all manual with mechanical linkages.
One Ends Another Begins
While GELAC engineers were working to improve the XV-4A aircraft ejector performance, the company received a contract in 1963 from the U.S. Army Transportation Research Command to conduct an ejector lift improvement program on a full scale static test rig using two Pratt and Whitney JT12A-3 engines.
A new ejector primary slot nozzle manifold designed to minimize the pressure loss of air entering the ejector was manufactured and tested, plus small changes to the ejector mixing chamber were made. These tests revealed an ejector thrust augmentation of 1.48 was achieved out of ground effect which exceeded the 1.4 original design goal.
However, these design changes were never installed in the aircraft before the first XV-4A was destroyed in an accident at Dobbins on 10 June 1964. Army pilot William Ingram was killed and the results of the accident investigation were inconclusive. No further XV-4A flights were made.
The first aircraft (62-4503) completed 73 hovers totaling about 8.5 hours and 52 flights totaling just over 20 hours of flight time. The second XV-4 (62-4504) had hovered nine times for about 54 minutes and had completed 17 flights for about 8.9 flight hours.
Shortly after the XV-4A program ended, the Air Force initiated its VTOL Flight Control Technology Program. GELAC modified the second aircraft, which was redesignated XV-4B.
Shaping the Future
On the XV-4B, the ejector thrust augmentation system and all the reaction control systems were removed. Four General Electric J85-GE-19 engines with swiveling nozzles were mounted vertically in the aircraft center fuselage space. The original nacelles with Pratt & Whitney JT12A-3 engines in the A-model were replaced with J85-GE-19 engines which provides thrust for both horizontal and vertical flight, and the vertical nozzles swiveled like the lift engine nozzles—six engines total. A new engine high pressure bleed air duct system connecting all engines provided the aircraft’s reaction control system.
“The XV-4B program was intended primarily to test a variable stability flight control system that could be reconfigured to replicate flight control systems of other future VTOL aircraft,” Shumpert said. “But we had to make sure it could fly first. I wasn’t in favor of the direct lift system because of all the very hot gasses that would build up underneath the aircraft, which would cause hot gas ingestion into the engine inlets on and near the ground in the vertical flight mode. All those engines would put out a lot of heat.”
The engineer’s fears would prove correct, as the heat blew out two sets of tires during initial testing. “To mitigate that problem, we built a hover pad with a grate about 10 inches off the ground that diverted the heat and gas,” Shumpert noted.
Company test pilot Bernie Dvorscak made the first flight of the XV-4B on 28 September 1968 in Marietta. The XV-4B program came to an end on 14 March 1969, when the aircraft began rolling uncontrollably during what was supposed to be a test of the lift engines at altitude. Company test pilot Hal Quamme ejected safely, but the aircraft dove straight down from 6,000 feet and was destroyed.
A total of 24 sorties, totaling just over 17 flight hours were completed in the XV-4B. No hovers or transition flights were completed.
The XV-4A was the first U.S. Army jet and the first ejector-powered VTOL aircraft. The XV-4B was the first flush lift engine inlet VTOL aircraft. Shumpert was responsible for all aspects of the Hummingbird propulsion and thermodynamic systems, including analysis, aerodynamic design, development testing of components and systems (vertical lift ejectors, reaction control valves, boundary layer control, lift engine inlets, thrust vectoring nozzles, complex hot air distribution ducts, and powered wind tunnel models), and flight test support.
The Rest is History
Shumpert went on to helm multiple other propulsion projects, including company IRAD programs and NASA-funded research efforts. He either authored or was a major contributor to 20 professional publications and gave several major professional presentations. He also holds two patents, including one, with Paul Bevilaqua, for the design of the integrated lift fan propulsion system used in the F-35B.
“It’s technology and computer control that makes vertical flight a success in the F-35B,” Shumpert noted. “In the XV-4B, the pilot had to make the decisions. They wanted more control than we could provide at that time. In the F-35B, with the flight computer, the pilot can fully control the aircraft in all axes with essentially no vertical thrust loss. Vertical flight has truly matured.”
The team that developed the integrated lift fan propulsion system and implemented it in the X-35 concept demonstrator (basically, the F-35B prototype) was honored with the Collier Trophy, the most prestigious award in American aviation in 2001. The Collier Trophy is given annually for the most outstanding achievement in American aviation
Shumpert retired in 1991. His work on the integrated lift fan propulsion system, and other vertical aircraft studies continued as he worked as a consultant to Lockheed Martin. During his consulting years, he was involved in designing the ejector nacelle cooling system for the new engine installation on the C-130J Super Hercules, and he was involved in defining the new engine fan thrust reverser configuration for the C-5M Super Galaxy.
“The Newbold award is quite an honor,” Shumpert concluded. “I never in my lifetime expected anything like this. It’s quite a way to wrap up a career.”
Written by Jeff Rhodes.