Engineering topics

Boles, R. A.

Publications and source records attributed to Boles, R. A..

5 records

NASA NTRS1978

Moving ground simulation by tangential blowing

Belt-type moving ground equipment, used for ground-effect simulation in STOL and VTOL tests, can be inconvenient and costly, especially in larger tunnels. In most cases such difficulties may be avoided by employing tangential blowing at the ground surface, from a single slot. The paper reviews several powered model tests using both moving ground and tangential blowing and describes the slot configuration, and the test techniques which were developed. Ground skin friction is monitored to set blowing levels and no model-dependent calculations are needed. It is also shown that application to center-tunnel testing can delay tunnel flow breakdown very considerably.

Hackett, J. E.↗

NASA NTRS1977

Aerodynamic characteristics of a small-scale straight and swept-back wing with knee-blown jet flaps

Two sting-mounted, 50.8 cm (20 in.) span, knee-blown, jet-flap models were tested in a large (2.1- by 2.5-m (7- by 10-ft) subsonic wind tunnel. A straight- and swept-wing model were tested with fixed flap deflection with various combinations of full-span leading-edge slats. The swept-wing model was also tested with wing tip extensions. Data were taken at angles-of-attack between 0 deg and 40 deg, at dynamic pressures between 143.6 N/sq m (3 lb/sq ft) and 239.4 N/sq m (5 lb/sq ft), and at Reynolds numbers (based on wing chord) ranging from 100,000 to 132,000. Jet flap momentum blowing coefficients up to 10 were used. Lift, drag, and pitching-moment coefficients, and exit flow profiles for the flap blowing are presented in graphical form without analysis.

Morehouse, G. G.↗

NASA NTRS1977

Ground simulation and tunnel blockage for a swept, jet-flapped wing tested to very high lift coefficients

Ground effects experiments and large/small tunnel interference studies were carried out on a model with a 20 inch (50.8 cm) 25 degree swept wing. The wing is slatted, has a 60 degree knee-blown flap and can be fitted with unflapped tips. A tail rake of pitch-yaw probes can be fitted to the fuselage. Certain check tests were also made with a very similar straight-wing model.

Hackett, J. E.↗

NASA NTRS1976

Ground simulation and tunnel blockage for a jet-flapped, basic STOL model tested to very high lift coefficients

Ground effects experiments and large/small-tunnel interference studies were carried out on a model with a 20-inch (50.8 cm) span wing. The wing, which includes a highly deflected knee-blown flap can be fitted with unflapped tips and slats. A low-mounted tailplane can be fitted to the aft fuselage. Three-component balance meaurements, made with a fixed ground equipped with a single boundary-layer blowing slot, were compared with datum, moving-ground results. Good comparisons were obtained up to model blowing momentum coefficients of approximately two, after which the particular floor blowing settings used proved insufficient to prevent floor separation in the vicinity of the model. Skin friction measurements, taken routinely along the floor centerline, proved invaluable during the analysis of results, and their use is recommended as input to determination of floor BLC setting. A careful investigation was made of pitching moments, including tail-on, close-to-ground cases, with favorable results. Drag proved the most sensitive to the change from a moving to the boundary-layer controlled ground.

Hackett, J. E.↗

NASA NTRS1972

Ground effect for V/STOL aircraft configurations and its simulation in the wind tunnel. Part 2: Experimental studies

Wind tunnel tests on a finite, knee-blowing-flapped wing and on a direct jet lift configuration were performed in a 30 x 42 inch wind tunnel. The objectives of these tests were, in experimental order:(1) to obtain definitive fixed-versus-moving ground comparisons on a powered, high-lift finite wing and on a lifting jet configuration as a function of model height and lift, (2) to understand the flow mechanism which lead to observed differences between moving and fixed-ground results, (3) to discover whether the above effects of a moving ground plane can be simulated by tangential-blowing boundary layer control at the wind tunnel floor, and (4) to check the form and the numerical constants for the wall jet blowing equation derived theoretically in Part I of this report. This relates wall jet blowing quantities to model lift coefficient.

Hackett, J. E.↗