A-4 Flight Characteristics A4 Recurrent training A-4 Flight Characteristics

A-4 Flight Characteristics Review flight characteristics of A-4 aircraft: Longitudinal characteristics: Longitudinal control sensitivity Trim changes with secondary control actuation Transonic Mach characteristic High speed dive recovery Maneuvering performance Lateral-directional characteristics: Roll performance Dutch roll characteristics Asymmetric stores Stall, departure and characteristics Spin characteristics and recovery procedures Power controls disconnected

A-4 Flight Characteristics Discussion based on: NATOPS Chapter IV (A-4M and TA-4J) Naval Air Test Center reports (A-4M and TA-4F) AFCS flight characteristics unavailable at this time

A-4 Flight Characteristics Longitudinal control sensitivity: Norm CG/0.85M: 3 lbs/g Aft CG/0.50M: 9 lbs/g Trim changes with control actuation: Gear/Flaps: slight nosedown Speedbrake: noseup, counterred by interconnnect Trim sensitivity at low altitude/high speed With slats locked up, exhibits neutral-to-negative longitidinal stability (pitch-up) at low speed. Conducive to inadvertent stall.

A-4 Flight Characteristics Mild nosedown trim change at 0.85 IMN Longitudinal control sensitivity and trim sensitivity at high speed Transonic pitch-up during high-g decel through 0.9 IMN (change in elevator effectiveness). 4 8 12 16 20 24 28 32 36 40 TIME - SEC FWDAFT MACH NUMBER INDICATED LONGITUDINAL STICK FORCE LB ACCELERATION NORMAL g pitch-up During accelerated recoveries from dives at supersonic speeds, a marked pitchup, proportional to existing load factor, will occur at approximately 0.95 IMN. This increase in load factor is partially due to a marked increase in elevator effectiveness when decelerating through 0.95 IMN. After the initial abrupt increase in load factor or pitchup, the load factor will continue to build up at a slower rate as Mach number is decreased below 0.95 IMN, unless the pilot relaxes aft pressure on the stick. The pitch-up severity depends on the initial load factor or stick position, being most severe for full aft stick. The following are the maximum initial load factors which may be established by the pilot during a decel through 0.85 IMN without exceeding limit load factor. These maxima are for the critical aft cg condition and assume that the pilot maintains constant stick force throughout the pitch-up. 10,000 feet 3.8g 20,000 feet 3.5g 30,000 feet 3.2g At altitudes above 15,000 feet, and at high load factors, aircraft buffet will be encountered above 0.95 tp 0.98 IMN. This buffet should be heeded as a warning to relax aft stick pressure. If corrective action is applied by prompltly relaxing the aft stick pressure, the pitchup can be appreciabley lessened.

A-4 Flight Characteristics HIGH SPEED DIVE RECOVERY The diving characteristics of the aircraft are normal except when steep dives are conducted in the clean configuration from high altitudes where airspeeds increase into the supersonic range. Under these conditions, elevator effectiveness is reduced and the aircraft’s basic stability becomes high, limiting the g available even with full aft stick. NATOPS dive recovery nomographs are duplicated above. The following are examples of the altitude loss during a dive pullout using a 4g pull after a 1 sec pilot delay, derived from the above tables: Initial Condition Altitude Loss 30°/300 KTAS 600 ft 45°/450 KTAS 2200 ft NATOPS also includes the following notes and cautions related to recovery from high-speed dives: NoteIf difficulty is experienced in recovering from dive, speedbrakes should be opened immediately and throttles retarded in an effort to reduce airpseed and limit altitude loss in the recovery. The maximum speed for fully effective opening of speedbrakes is 440 KIAS. Speedbrakes are partially effective up to maximum speed capabilities of the aircraft; however, a slow uncommanded roll may occur at airspeeds above 440 KIAS due to asymmetric speed-brake extension. Roll is easily countered by small lateral inputs. If the elevator power system should fail during a supersonic dive, the stick force required for recovery will be so high as to prohibit normal recovery procedures. Use of aircraft noseup stabilizer trim will then become mandatory to effect recovery. Do not use the horizontal stabilizer as a dive recovery device except in an emergency. A pitchup will occur as the airspeed drops below approximately Mach 0.94, increasing the chance of structural overstress. If the speedbrakes are used before entering the dive, airspeeds will be limited to lower values where the increase in stick forces will not be severe. NoteThe speedbrakes will begin to “blowback” at approximately 490 KIAS. Add the values from these two tables to obtain total lost in altitude from initiation of the dive recovery to level flight. NOTE The altitude loss given is for a constant airspeed pullout. Flight tests have shown actual altitude loss to be 1,000 ft to 2,000 ft greater than computed values due to aircraft acceleration at high power settings or steep dive angles.

A-4 Flight Characteristics MANEUVERING FLIGHT AVAILABLE MANEUVERABILITY GROSS WEIGHT = 14,721 POUNDS CG @ 20.9 MAC The “V-N” diagrams illustrated above depict the maneuvering capability (“g” available) for the A-4 at sea level and at 15,000 ft MSL. The “corner speed” is shown to be about 360 KCAS (0.58 Mach at sea level and 0.74 Mach at 15Kft.). This speed is significant in that it is the minimum speed at which the airplane is capable of achieving the structural limit g, and is also the speed at which the airplane can achieve the greatest turn rate. Prior to performing any high angle of attack or maneuvering flight, a slat check should be performed using the procedures listed above.

A-4 Flight Characteristics LATERAL-DIRECTIONAL CONTROL CHARACTERISTICS Full, Against Stop Partial Normal (Boosted) Manual 300 Roll performance 180-250°/s (cruise) 30-50°/s (approach) Dutch roll characteristics: With yaw damper OFF, Dutch roll very lightly damped (z < 0.2), and easily excited. Expected to be well-damped (z = 0.3 to 0.6) with yaw damper ON. Miscellaneous: Slats: rolling moment with asymmetric deployment

A-4 Flight Characteristics ASYMMETRIC STORES Flight manual recommendations for landing with asymmetric stores: Perform straight-in approach Maintain normal approach AOA, not less than: 115 KIAS for 7,500 ft-lbs asymm 130 KIAS for 12,500 ft-lbs asymm Put crosswind under heavy wing Use min rate of descent touchdown On manual flight controls: Max 7500 ft-lbs asymm Min 140 KIAS initial approach speed, 125 KIAS final

A-4 Flight Characteristics STALL CHARACTERISTICS Stall warning: mild airframe buffet 5-15% above Vs, increasing in intensity to stall Stall characterized by mild nosedown pitching and light lateral-directional oscillation Recover by:-decreasing AOA with forward stick -adding full power -rolling wings level 1g STALL SPEEDS SPEEDBRAKES RETRACTED GEAR DOWN

A-4 Flight Characteristics DEPARTURE CHARACTERISTICS A-4’s are not departure prone. Most departures are result of: Nose-high, low airspeed conditions Asymmetric slat extension Proper recovery procedure: Hold and visually check controls neutral laterally and slightly aft Reduce power below 80 percent RPM Ensure pitch trim 0-4 deg nose up During post-stall gyrations (PSG), pilot must accept the random roll/yaw oscillations and maintain neutral controls. Control inputs (intentional or inadvertent) will prolong the departure and possibly result in spin entry.

A-4 Flight Characteristics DEPARTURE For any departure from controlled flight: Hold and visually check controls neutral, with stick neutral to slightly aft Lock harness Reduce throttle below 80% Check elevator trim 0 to 4 degrees nose up Check flaps up, speedbrakes in Check altitude. If out of control passing 10,000 ft AGL, EJECT Positively recheck controls neutral

A-4 Flight Characteristics SPINS Spin entry usually requires pro-spin controls to be applied and maintained. Following inadvertent departure, do not apply spin recovery controls until spin confirmed! sustained yaw rate low airspeed (below 200 KIAS) pegged AOA Certain post-stall gyrations (PSG’s) are easily confused with an inverted spin. Differences are that: AOA oscillating airspeed continually increases If airspeed is increasing through 200 KIAS, the aircraft is definitely not spinning. maintain controls neutral monitor AOA, airspeed and altitude commence dive recovery as airspeed increases through 200 KIAS if residual roll at 200 KIAS, stop the roll with aileron then commence dive recovery

A-4 Flight Characteristics UPRIGHT SPINS The A-4 exhibits two types of upright spins: Steep oscillatory (most common) AOA: 20 to 30 units Turn needle: Pegged in direction of spin, but may come off peg occasionally as yaw rate hesitates Airspeed: Usually increases as spin progresses (may indicate faster than 150 KIAS) Flat (least common) AOA: Pegged at 30 units Turn needle: Pegged in direction of spin Airspeed: Stabilized 50 to 150 KIAS Typical upright spin data: Rotation rate 4 to 14 sec/turn Altitude loss 2000 to 7000 ft turn Rate of descent 20,000 to 35,000 ft/min

A-4 Flight Characteristics INVERTED SPIN CHARACTERISTICS Most common A-4 spin mode is inverted spin: Oscillatory, extremely disorientating Recovery complicated by poor A-4 restraint system Characteristics: AOA: Near zero units Turn needle: Pegged in direction of spin Airspeed: Stabilized 50 to 150 KIAS Typical inveted spin data: Rotation rate 3 to 4 sec/turn Altitude loss 800 to 1200 ft turn Negative load factor over 2.5g possible

A-4 Flight Characteristics SPIN RECOVERY PROCEDURES Maintain controls positively neutral until recovery is effected or both angle of attack and turn needle are pegged, then apply and maintain recovery controls. The recovery controls for an erect spin are full rudder against the spin (opposite direction of the turn needle), full aileron with the spin, and longitudinal stick position from neutral to slightly aft. When spin rotation stops, neutralize all controls. The recovery controls for an inverted spin are full aileron and full rudder against the spin (opposite direction of the turn needle). Longitudinal stick position must be neutral to slightly aft; forward stick will impede recovery The ailerons are the primary recovery control and aircraft response will occur in the form of roll in the direction of hte applied aileron. Spin rotation will slow or hesitate as the aircraft rolls erect, however, this should not be mistaken for spin recovery. The aircraft will frequently continue thhe inverted spin after momentarily rolling erect. Maintain anti-spin controls until there is a positive indication of spin recovery, i.e. AOA other than pegged and airspeed increasing rapidly.

A-4 Flight Characteristics SPIN RECOVERY PROCEDURES Maintain controls positively neutral until recovery is effected or both angle of attack and turn needle are pegged, then apply and maintain recovery controls. The recovery controls for an erect spin are full rudder against the spin (opposite direction of the turn needle), full aileron with the spin, and longitudinal stick position from neutral to slightly aft. When spin rotation stops, neutralize all controls. The recovery controls for an inverted spin are full aileron and full rudder against the spin (opposite direction of the turn needle). Longitudinal stick position must be neutral to slightly aft; forward stick will impede recovery The ailerons are the primary recovery control and aircraft response will occur in the form of roll in the direction of hte applied aileron. Spin rotation will slow or hesitate as the aircraft rolls erect, however, this should not be mistaken for spin recovery. The aircraft will frequently continue thhe inverted spin after momentarily rolling erect. Maintain anti-spin controls until there is a positive indication of spin recovery, i.e. AOA other than pegged and airspeed increasing rapidly.

A-4 Flight Characteristics FLIGHT WITH POWER CONTROLS DISCONNECTED Power System Manual Operative Control 180-250°/s (cruise) As little as 10°/s Roll performance 30-50°/s (approach) at 300 kts/S.L. Longitudinal control 3 lbs/g (norm CG/0.85M) 120 lbs control force: effectiveness/ 9 lbs/g (aft CG/0.50M) 1.8g @ 0.96M sensitivity 2.7g @ <0.85M Power control disconnect above 300 KIAS or Mach 0.80, whichever is lower, should be avoided if at all possible. Reduce thrust and open speedbrakes to decrease Mach to this value before disconnecting. Trim aircraft laterally prior to disconnect, if possible. The aircraft is subject to strong wing dropping tendencies above mach 0.90, with the boost disconnected. Available rate of roll with maximum pilot effort in this speed range may be insufficient to overcome wing dropping tendencies. Although the aileron tab retains some effectiveness, the slow speed of operation of this tab makes it difficult to keep up with the random wing dropping. Wing dropping tendency disappears as airspeed is reduced to Mach 0.85, and available roll rate from pilot input forces increase, making the aircraft once more controllable.