Free-flight investigation at transonic speeds of the power-on characteristics including some effects of sonic propulsive jets of a four-engine delta-wing configuration Page: 2 of 49
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NASA Technical Libra
NACA RM L57E31 T 3 1176 01437 2719
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
FREE-FLIGHT INVESTIGATION AT TRANSONIC SPEEDS OF THEE
POWER-ON CHARACTERISTICS INCLUDING SOME EFFECTS
OF SONIC PROPULSIVE JETS OF A FOUR-ENGINE
By Joseph H. Judd and Ralph A. Falanga
A free-flight model of a delta-wing configuration with four engines
mounted two to a nacelle below the wing was flight tested with rocket
turbojet simulators operating from Mach numbers 0.58 to 1.36 and from
Reynolds numbers 39 x 10 to 97 x 106; with jets off the Mach numbers
ranged from 1.20 to 1.36. Jet-exit static-pressure ratios were about
2.7 for jet-on flight. At Mach number 0.58 the wing static-pressure
coefficients were small and appeared to change little between jet-on and
jet-off flight. At supersonic speeds, jet-on wing pressure coefficients
alternated between positive and negative values. Jet-on flight at Mach
number 1.3 was at a nose-down trim angle of attack caused by the pressure
field of the jet. A positive increment in lift coefficient was produced
by the jet pressure field between jet-on and jet-off flight at Mach num-
The study of the effect of the flow field about a propulsive jet on
flat-plate pressure distribution (refs. 1, 2, 3, and 4) and on tail sur-
faces (refs. 5 and 6) has shown that appreciable forces and moments may
result from jet interference. Since the airplane flow field is warped by
curvature of wing and component interferences, appreciable difference in
jet effect may result between simple flat plates and an airplane configu-
ration. For this reason, flight tests of a complete four-jet bomber model
were made to measure the wing static-pressure distribution behind the jet
exits and to compare the changes in measured trim of the configuration
with the loads induced by the jet exhaust. This investigation was per-
formed by the Langley Pilotless Aircraft Research Division as part of a
program to study various aspects of the effect of a sonic propulsive jet
t drag and stability of airplane configurations.
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Judd, Joseph H. & Falanga, Ralph A. Free-flight investigation at transonic speeds of the power-on characteristics including some effects of sonic propulsive jets of a four-engine delta-wing configuration, report, August 16, 1957; (digital.library.unt.edu/ark:/67531/metadc63486/m1/2/: accessed January 23, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.