FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1962
1962 - 0514.PDF
512 FLIGHT International, 5 April 1962 Landing transition boundaries; the procedure for transition to a vertical landing is outlined in the text below HUMMINGBIRD .. . during the transition, and would require about one minute if the pilot proceeded from each phase to the next as soon as the conversion speed was attained. All transition programmes within the accelera tion boundaries are relatively easily flown. The pilot is required to monitor only airspeed and altitude, in addition to effecting two single diverter-valve movements. Transition from level flight for a vertical landing is initiated by diverting both engines to downward thrust at idle power. As forward speed decreases, power is increased to maintain altitude. Below about 60kt angle of attack may be increased beyond the stall to reduce transition time. As speed falls to zero the angle of attack is decreased so that hovering flight is smoothly achieved. Pitch-attitude boundaries are plotted for level flight deceleration at sea level for standard day conditions at a landing weight of 5,5001b. The upper boundary of the transition zone at speeds less than 60kt is defined by an attitude and buffet limit (at present not well defined). Between 60 and 95-103kt the upper boundary is defined by the attitude corresponding to either CL max or, more conservatively, about 82 per cent CL max. The boundary over 103kt separates the transition zone from conventional flight. From zero to 89kt the lower boundary is defined by the conditions for steady- state flight (i.e., below this boundary acceleration rather than decleration will occur). At over 89kt the minimum pitch attitudes are limited by the power available. These boundaries are representative of those for higher altitudes at the same weight. The T/W ratio would be reduced, but its only effect would be to raise the maximum-power boundary (provided that forward speed is interpreted as EAS). For higher weights and altitudes the major effect would still be to raise the maximum- power boundary; at 6,5001b at 2,500ft on a standard day the maxi mum-power, minimum-pitch attitude would be —9.5° at lOOkt and -8.0° at 140kt. Typically, the schedule of pitch-attitude with decreasing velocity is one of essentially constant attitude down to low flight speeds. Since the decelerating forces become quite low at low speeds the nose can be raised slightly to assist in dissipating the kinetic energy. This typical transition would require about 30sec from engine conversion to hover. With one engine inoperative and the other at take-off power the maximum static T/W is 0.57 for 7,2001b and 0.74 for 5,5001b. The upper limits of the "caution zones" are defined by the combi- natio ns of speed and altitude from which a diving recovery can be made iri the event of single engine failure during horizontal flight below Vsi. Recovery from these boundaries permits the attainment of zero rate of sink at zero altitude, and the forward thrust from the operative engine permits conventional flight to an area where a conventional landing can be made. The lower boundaries are defined by the combinations of speed and altitude which permit the landing gear to absorb the landing k.e. One boundary is based Ofl a rate of sink of 16.7ft/sec at the ground, and the upper 20ft/ssc; any number of landings can be made from the first boundary with out damage, whereas landings from the higher boundary would result in plastic deformation. Hovering roll power exceeds helicopter requirements (including damping) of MIL-H-8501A. These requirements demand a roll angle of 4° after 0.5sec; the Hummingbird will roll up to 5.5° in 0.5sec. Hovering pitch control exceeds the requirements of MIL-H-8501A simultaneously with full available yaw control; a pitch angle of 12° is attained after lsec, with the specified damping. Yaw power is less than that specified in MIL-H-8501 and 8501 A. Yaw of 4.6° can be reached in lsec with the yaw damping specified in MIL-H-8501 A, and 7.0° with inherent airframe damping. It is felt that in VTOL test vehicles little hazard should result from lack of yaw control. Small-scale ejector tests led to construction of a major rig. Initially powered by two 1,0001b Fairchild J44 engines, this rig was capable of lifting over 2,6001b, pitch and roll control nozzles being supplied with plant air through hoses. Conventional stick and rudder pedals were used for controlling the reaction nozzles, and an autopilot (later considered unnecessary) augmented pitch and roll stability. This rig was successfully operated over a period of more than 24 months. In conclusion, something may be said of the proposed sensory equipment which could be installed in the belly pod of the produc tion aircraft. Low-altitude side-looking radar, employing beam- sharpening by Doppler techniques, would provide high-resolution strip maps of terrain on both sides of the flight path. An infra-red subsystem would produce horizon-to-horizon strip maps along the line of flight. A day camera system, using a single rotary, panoramic installation, would have 180° sweep in azimuth and 50 sweep in elevation. A night camera system, using a stationary forward, oblique, dual-lens camera, would provide 70° by 50c coverage on two single-frame formats; an electronic stroboscopic flash unit would illuminate the terrain below. Long range, side- looking radar would be provided for ground mapping from up to 40,000ft, and would permit mapping deep into enemy territory from inside friendly territory. Detectors would sense air and ground contamination following nuclear explosions. LOCKHEED-GEORGIA 330 HUMMINGBIRD Two Pratt & Whitney JT-12-7 turbojets, rated at 3,3001b each Dimensions Span, 25ft Sin; length, 32ft 8m; tailplane span, 10ft lOin; wing area, I04sqft. Weights Research version, wing, 4011b; empennage, 1871b; fuselage, 1,0651b landing gear, 3101b; nacelles, 2721b; propulsion and lift system, 1,6041b; instru ments, 651b; controls, 3331b; electrics, 5271b; hydraulics, 801b; furnishings, 1511b; weight empty, 4,9951b; crew, 2001b; test equipment, 3001b; trapped fuel/oil, 301b; equipped weight, 5,5251b; fuel, 1,6751b; gross weight. 7,200 lb. Operational version, weight empty, 4,9891b; gross weight, 7,9751b; weights of sensory pod equipment, low-alt radar, 2261b; night photo, 601b; day photo and radiological, 1361b; infrared, 2231b; high-ait radar, 3581b. Performance Operational version, max airspeed, 575kt; mission radius with 6001b pod, 170 n.m. at sea level, 230 n.m. at 15,000ft, 295 n.m. at 25,000ft and 360 n.m. at cruise ceiling (limit height is 40.000ft): rate of climb at 7.2001b, 11,500k mm at sea level, 8.000ft mm at 20,000ft. Propulsion and control forces for the VZ-10 research aircraft VERT T.0. LOCATION & INITIAL TRANS THRUST-LBS 2ND SEG H0R FLT WITH OF TRANS BOTH ENGINES (80 KNOTS) (120 KNOTS) i ROLL CONTROL HORIZONTAL ENGINE THRUST H E-F C EJECTOR THRUST PITCH CONTROL C HORIZONTAL ENGINE THRUST PITCH CONTROL ROLL CONTROL MAXIMUM VALUES
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
