A-4 Flight Characteristics A4 Recurrent training.

A-4 Flight Characteristics

A4 Recurrent training

A-4 Flight Characteristics

Review flight characteristics of A-4 aircraft:Longitudinal characteristics:Longitudinal control sensitivityTrim changes with secondary control actuationTransonic Mach characteristicHigh speed dive recoveryManeuvering performanceLateral-directional characteristics:Roll performanceDutch roll characteristicsAsymmetric storesStall, departure and characteristicsSpin characteristics and recovery proceduresPower 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/gAft CG/0.50M: 9 lbs/gTrim changes with control actuation:Gear/Flaps: slight nosedownSpeedbrake: noseup, counterred by interconnnectTrim sensitivity at low altitude/high speedWith 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 IMNLongitudinal control sensitivity and trim sensitivity at high speedTransonic pitch-up during high-g decel through 0.9 IMN (change in elevator effectiveness).

0 4 8 12 16 20 24 28 32 36 40

TIME - SEC

FW

DA

FT

IND

ICA

TE

DM

AC

H N

UM

BE

RL

ON

GIT

UD

INA

LS

TIC

K F

OR

CE

LB

NO

RM

AL

AC

CE

LE

RA

TIO

Ng

pitch-up

A-4 Flight CharacteristicsHIGH SPEED DIVE RECOVERY

Add the values from these two tables to obtain total lost in altitude from initiation of the dive recovery to level flight.

NOTEThe 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.

Add the values from these two tables to obtain total lost in altitude from initiation of the dive recovery to level flight.

NOTEThe 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 CharacteristicsMANEUVERING FLIGHT

AVAILABLE MANEUVERABILITYGROSS WEIGHT = 14,721 POUNDS

CG @ 20.9 MAC

A-4 Flight CharacteristicsLATERAL-DIRECTIONAL CONTROL CHARACTERISTICS

Roll performance180-250°/s (cruise)30-50°/s (approach)

Dutch roll characteristics:With yaw damper OFF, Dutch roll very lightly damped ( < 0.2), and easily excited.Expected to be well-damped ( = 0.3 to 0.6) with yaw damper ON.

Miscellaneous:Slats: rolling moment with asymmetric deployment

Full, Against StopPartialPartial

Normal (Boosted)ManualManual

300

A-4 Flight Characteristics

ASYMMETRIC STORES

Flight manual recommendations for landing with asymmetric stores:

Perform straight-in approachMaintain normal approach AOA, not less than:115 KIAS for 7,500 ft-lbs asymm130 KIAS for 12,500 ft-lbs asymmPut crosswind under heavy wingUse min rate of descent touchdownOn manual flight controls:Max 7500 ft-lbs asymmMin 140 KIAS initial approach speed, 125 KIAS final

A-4 Flight CharacteristicsSTALL CHARACTERISTICS

Stall warning: mild airframe buffet 5-15% above Vs, increasing in intensity to stallStall characterized by mild nosedown pitching and light lateral-directional oscillationRecover by:-decreasing AOA with forward stick-adding full power-rolling wings level

1g STALL SPEEDSSPEEDBRAKES RETRACTED

GEAR DOWN

A-4 Flight CharacteristicsDEPARTURE CHARACTERISTICS

A-4’s are not departure prone. Most departures are result of:Nose-high, low airspeed conditionsAsymmetric slat extension

Proper recovery procedure:Hold and visually check controls neutral laterally and slightly aftReduce power below 80 percent RPMEnsure 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 CharacteristicsDEPARTURE

For any departure from controlled flight:

Hold and visually check controls neutral, with stick neutral to slightly aftLock harnessReduce throttle below 80%Check elevator trim 0 to 4 degrees nose upCheck flaps up, speedbrakes inCheck altitude. If out of control passing 10,000 ft AGL, EJECTPositively recheck controls neutral

A-4 Flight CharacteristicsSPINS

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 ratelow airspeed (below 200 KIAS)pegged AOACertain post-stall gyrations (PSG’s) are easily confused with an inverted spin. Differences are that:AOA oscillating airspeed continually increasesIf airspeed is increasing through 200 KIAS, the aircraft is definitely not spinning.maintain controls neutralmonitor AOA, airspeed and altitudecommence dive recovery as airspeed increases through 200 KIASif residual roll at 200 KIAS, stop the roll with aileron then commence dive recovery

A-4 Flight Characteristics

UPRIGHT SPINSThe A-4 exhibits two types of upright spins:Steep oscillatory (most common)•AOA: 20 to 30 unitsTurn needle: Pegged in direction of spin, but may come off peg occasionally as yaw rate hesitatesAirspeed: Usually increases as spin progresses (may indicate faster than 150 KIAS)Flat (least common)AOA: Pegged at 30 unitsTurn needle: Pegged in direction of spinAirspeed: Stabilized 50 to 150 KIAS

Typical upright spin data:Rotation rate 4 to 14 sec/turnAltitude loss 2000 to 7000 ft turnRate of descent 20,000 to 35,000 ft/min

A-4 Flight CharacteristicsINVERTED SPIN CHARACTERISTICS

Most common A-4 spin mode is inverted spin:Oscillatory, extremely disorientatingRecovery complicated by poor A-4 restraint systemCharacteristics:AOA: Near zero unitsTurn needle: Pegged in direction of spinAirspeed: Stabilized 50 to 150 KIAS

Typical inveted spin data:Rotation rate 3 to 4 sec/turnAltitude loss 800 to 1200 ft turnNegative load factor over 2.5g possible

A-4 Flight CharacteristicsSPIN RECOVERY PROCEDURES

OUT OF CONTROL *1. Controls – NEUTRAL *2. Harness – LOCKED *3. Throttle – MIDRANGE

*4. Trim – 0 to 4

*5. Flaps/Speedbrakes/Slats—CHECK

*6. Alt/Airspeed/AOA/Turn Needle—

ANALYZE

1W

2W

3N

4W

OUT OF CONTROL

The stick (elevator) should be positioned and visually verified slightly aft of the neutral position. Failure to set pitch trim between 0-4° NOSE-UP can delay or prevent recovery. A. Speed-brake—IN B. Flaps—UP C. Slats—Symmetrical extension If passing below 10,000 ft AGL in uncontrolled flight—EJECT. Ejection should not be delayed because of the extremely high rates of descent (22,000 to 35,000 FPM). Ejection guidelines are not meant to prohibit earlier ejection. If insufficient altitude exists to recover from departed flight, the aircrew should not hesitate to eject.

1W

2W

3N

4W

A-4 Flight CharacteristicsSPIN RECOVERY PROCEDURES

SPIN RECOVERY (Upright/Inverted)

*1. Analyze—Alt, Airspeed, AOA, Turn needle If spin confirmed UPRIGHT:

*2. Aileron and Rudder – INTO AND OPPOSITE

TURN NEEDLE

*3. Elevator— NEUTRAL TO SLIGHTLY AFT If spin confirmed INVERTED:

*2. Aileron and Rudder – OPPOSITE AND

OPPOSITE TURN NEEDLE

*3. Elevator— NEUTRAL TO SLIGHTLY AFT When airspeed increases or rotation stops:

*4. Controls – NEUTRAL.

*5. At 200 KTS—PULL (18 to 20 units)

*6. Out of control passing 10,000 feet AGL –

EJECT

1C

3C

2W

2W

4W

SPIN RECOVERY (Upright/Inverted) Airspeed—Low; 50 to 150 AOA– 30 unit (upright), /0 unit (inverted) Turn Needle—Pegged, indicates direction of spin Location of stick neutral point may be extremely difficult to determine since up to 20 pounds of stick pull force may be required to keep the stick centered during inverted spin recovery. The pilot should determine a cockpit reference point for neutral stick positioning prior to flight. Spin recovery controls must be applied smoothly. It is imperative that the pilot maintain anti-spin controls as the aircraft rolls upright during the hesitant inverted mode. It may appear that the aircraft is recovering from the spin; however, increasing airspeed is the surest indication that recovery is effected and that the aircraft will not reenter the spin. Ejection should not be delayed because of extremely high rates of descent (22,000 to 35,000 FPM).

1C

2W

3C

4W

A-4 Flight CharacteristicsFLIGHT WITH POWER CONTROLS DISCONNECTED

Power System Manual Operative Control180-250°/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