Air Fronts: Aircraft Technical and Test Resources: Aircraft Manuals - RAF Pilot's Notes. AP 2095

Air Fronts: Aircraft Manuals - RAF Pilot's Notes: A.P 2095, Pilot's Notes - General, 1943 - Part 3: Accessories

A.P 2095, PILOT'S NOTES GENERAL, PROMULGATED BY ORDER OF THE AIR COUNCIL , 2ND Edition , April 1943. FOR OFFICIAL USE ONLY

PART III - ACCESSORIES

NOTE A. - GYRO FLYING INSTRUMENTS

1. Checking Instruments before Take-off.

(i) Before taking off at night, or in bad visibility by day, it is vital that the pilot should check the operation of his artificial horizon and direction indicator.

(ii) These instruments require two minutes running at a sufficient suction in order to attain the necessary speed for correct functioning. (This time and suction will also be sufficient for the turn and bank indicator.) On aircraft fitted with a suction gauge the requisite suction will be indicated by a line on the gauge. It should he obtained with the engine running at a fast tick-over. During warming up the pilot should check that this suction is obtained and held during the necessary two minutes.

(iii) The pilot should check the functioning of the instruments after warming and running up the engine(s) :

(a) Check that the artificial horizon has taken up the horizontal position and indicates correctly the pitch angle of the aircraft when standing on the ground.

(b) Set the direction indicator to correspond with the compass reading, uncage it, and turn the aircraft through about 45°. The indication of the direction indicator should then correspond closely with the new compass reading.

(c) The pilot should also check while turning on the ground that the turn and bank indicator shows correctly in which direction the aircraft is turning and shows outward sideslip.

(iv) If the take-off is delayed the engine should be kept at a fairly fast tick-over in order to keep the gyro instruments running to speed.

2. Checking in Flight.

Should the suction fail the failure will not at once be evident in malfunctioning of the instruments. When it is necessary to rely on these instruments the pilot should, therefore, check the suction from time to time (if a suction gauge is fitted).

3. Errors in Artificial Horizon in Take-off and Turns.

(i) During take-off the gyro tilts slowly nose downwards, lowering the horizon bar and so indicating that the aircraft is more nose up than it really is. The error grows while the aircraft is gathering speed and it is gradually corrected when the speed has become steady. Although the accumulated error is never very large, pilots should not rely on the pitch indication during take-off without allowance for the error (which may be observed in take-offs when a natural horizon is visible). The lateral level is quite closely maintained.

(ii) During turns the artificial horizon acquires temporary errors of a few degrees both in bank and in pitch, the amount of error depending on the rate of turn, air speed and change of course. Immediately after the turn the aircraft appears to be still banked when the wings are level and the nose appears to be more up than it really is. These errors are not important for maintaining control of the aircraft in blind flight, except very near the ground, but they can seriously upset bombing runs. The errors will be corrected in about two minutes of straight flight, or they may be allowed for after observations in flights in which a natural horizon is visible.

(iii) The Mark IB artificial horizon eliminates the errors for a Rate r turn at 200 m.p.h. T.A.S. and considerably reduces the errors for other speeds and rates of turn.

(iv) Quick turns on the ground, however, give rise to small errors in the Mark IB, mainly in bank in turns to port and mainly in pitch in turns to starboard. The errors disappear within a minute of the completion of the turn.

4. Special Points on American Instruments.

(i) To avoid the possibility of accidents arising from incorrect use of the caging device fitted to American artificial horizons, action has been taken to have this device made inoperative (A.P. 1275/K19). Should, however, American aircraft come into service with the caging device still operative, until the operating shaft is removed, care must be taken on entering the cockpit to check that the horizon is fully uncaged, and it should be left uncaged.

(ii) The aircraft datum of some American artificial horizons is adjustable. The adjustment should be checked after running up the engines before each Hight. The horizontal datum line on the pillar carrying the miniature aircraft should be in line with and just visible above the top of the mask. A knob is provided for making this adjustment. (These adjustable instruments have been fitted to some British, as well as American, aircraft.)

5. Further information.

Reference may be made to A.P.1275, Instrument Manual, Vol. 1, Sect. I. Chap. 4, 5, 6.

PART III - NOTE B - THE AUTOMATIC PILOT MK. IV

1. General.

(i) The Automatic Pilot Mk. IV has two gyroscope units :

(1) the Rudder and Elevator Unit,

(2) the Aileron Unit,

which govern the operation of the three aircraft controls by servo-motors

(ii) Power to drive the gyroscopes and to operate the servo-motors is provided by an air compressor on one of the engines. The Automatic Pilot also requires a supply of electricity when making turns.

(iii) The Mk. IV Pilot was originally designed to produce flat turns, and a pilot's control (the Speed Lever) was provided for this purpose. This control is no longer fitted. The Automatic Pilot gives a few degrees of bank during turns.

2. Pilot's Controls of the Automatic Pilot.

(i) The Clutch Lever disconnects the servo-motor from the aircraft controls. The direction of movement is indicated by the word OUT and an arrow. To clutch in from the out position the lever must be pulled sideways first to disengage it from a gate.

(ii) The Control Cock has three settings OUT, SPIN and IN and turns on the air supply.

(a) to drive the gyros . . .. .. . . SPIN

(b) to free the gyros and to bring the servomotors into action .. .. .. IN

(iii) The Main Switch connects the electricity supply for making turns.

(iv) The Steering Lever is used for changing course and is moved in the direction shown by an arrow and the word LEFT or RIGHT in order to make turns to the left or the right. The rate of turn is regulated by the amount of movement of the lever. A steering control is also fitted in the bomb-aimer's compartment.

(v) The Attitude Control is operated by a hand-crank, the direction of rotation for raising the nose of the aircraft being indicated by the word UP and an arrow. The setting is shown by an adjacent pointer and scale. The range is roughly from 20° up to 20° down.

(vi) The Air Pressure and Trim Gauge shows, on the right, the supply pressure in the mains and, on the left, the trim of the aircraft, TAIL HEAVY or NOSE HEAVY.

3. Operation.

(i) Before take-of:

(a) Move the Clutch Lever fully over against the arrow to the in position. (Leave the Main Switch off.)

(b) Move all the aircraft controls fully over both ways to ensure engagement of the clutches.

(c) With engines running and 6o lb. per sq. n. on the pressure gauge, check that the aircraft controls are free with the Control Cock at OUT and at SPIN. Leave at OUT.

(ii) After take-off:

As soon as convenient set the control cock to SPIN. The Automatic Pilot will be ready for use 5 minutes later.

(iii) Engaging the Automatic Pilot:--

(a) Trim the aircraft with the tabs to fly as nearly as possible " hands and feet off" at the desired speed on the desired course.

(b) Set the Attitude Control to correspond as nearly as you can with the pitch attitude of the aircraft. (Errors of setting will cause a slow change of attitude.)

NOTE.-- A kick may be felt on the elevator. If this kick is found to be large at heavy load and small at light load, or vice versa, the maintenance personnel should be asked to adjust the cables to produce a moderate kick at each extreme.

(d) If the aircraft departs from the desired pitch attitude, allow it to settle and then move the Attitude Control slowly in the required direction until the desired attitude is obtained.

(iv) Changing course:

(a) Set the Main Switch on.

(b) Move the Steering Lever in the required direction.

(d) Set the Main Switch off.

NOTE.-The Main Switch should be on only while making turns and off for long straight courses because of the difficulty of centralizing the Steering Lever accurately, especially at night.

(v) Maintenance of Trim:

The aircraft should be kept in longitudinal trim by adjusting the elevator trimming tabs so as to centralize the needle of the Trim Gauge.

(vi) Return to Manual Control:-Set the Control Cock to SPIN.

(vii) Before landing:

(a) Turn the Control Cock to OUT.

(b) See that the Main Switch is off.

NOTE 1.-The Control Cock should not be turned to OUT in flight so long as the Automatic Pilot may be required again; for the gyros will run down and require a few minutes to spin up.

NOTE 2.-The clutches should never be taken out in flight, except in emergency, as it may not be possible to re-engage them. It is essential to clutch in before take-of.

4. Reporting Failures.

In the event of a failure the following information may be of great value to maintenance personnel:

(a) Air supply pressure at time of failure.

(b) Behaviour of the aircraft.

(d) Atmospheric temperature at time of failure.

(e) Whether the Automatic Pilot functioned subsequently.

(f) Other comments on the failure.

5. Use of Automatic Pilot after Engine Failure.

(i) As power for the Automatic Pilot is provided by an air compressor driven by one of the engines it cannot be used if this engine has seized, or with its propeller fully feathered. If this engine has failed but can safely be windmilled, the Automatic Pilot can be used with the engine running at sufficient r.p.m. to give the normal air pressure.

(ii) If the failure occurs when under automatic control the live engine (or the live engine corresponding to the dead engine) should be throttled back at once and the Automatic Pilot disengaged. It may be re-engaged subsequently as below.

NOTE.--Automatic control should not be attempted with two engines dead on one side.

(iii) To engage the Automatic Pilot after engine failure:--

(a) If the air compressor is on the dead engine set its propeller to minimum r.p.m. (or least r.p.m. to give 55lb./ sq. in. pressure); otherwise, feather the propeller.

NOTE.-Electrical propellers can be run below the minimum controlled r.p.m. by using the manual control.

(b) After opening up the live engine(s) as necessary, trim for straight flight with wings level. Note the rudder trim setting.

(c) Throttle back the live engine corresponding to the dead one, maintaining straight flight and trimming the rudder as necessary.

(d) Engage the automatic pilot.

(e) Open up the engine again steadily, retrimming to the noted setting as the engine is opened up.

(iv) The Automatic Pilot can only hold on rudder with the gyro proportionately displaced in azimuth relatively to the aircraft. The aircraft will, therefore, change course as the engine is opened up and rudder is applied-to port, with a port engine failure. Allowance should be made for this departure from course by heading the aircraft some degrees off the desired course before engagement. Correction of course by the steering lever against the pull of the live engine may he very slow, unless the live engine is throttled back somewhat.

(v) If the change in heading as the engine is opened up under automatic control exceeds about r 5° the gyro of the Rudder and Elevator Unit may be in danger of fouling its stops and applying full up or down elevator according to the direction of turn. This may be dangerous and the pilot should throttle back and disengage before the departure from course exceeds 15°

(vi) Alternative method to avoid loss of height:

(a) Disengage the Automatic Pilot at once (if in control) without throttling back, checking swing with the rudder

(b) After opening up the live engine(s) as necessary, trim for straight flight with the wings level making allowance for change of course as the Automatic Pilot takes control.

(c) Holding the rudder firmly, engage the Automatic Pilot. The Automatic Pilot will endeavour to bring the rudder central and this should be resisted by pressure on the rudder bar.

(d) Ease off the pressure slightly to allow the aircraft to turn slowly. The Automatic Pilot will gradually relieve the foot load as the aircraft turns off course and it takes over control.

6. Further Information.

Reference may be made to A.P. 1469A "Aircraft Automatic Controls Mk. IV."

PART III. NOTE C - THE SPERRY GYROPILOT (Types A.2 and A.3)

1. Description.

(i) The Sperry Gyropilot includes the usual blind flying instruments:

(a) the direction indicator (Directional Control Unit);

(b) the artificial horizon (Bank and Climb Control Unit) together with

(ii) The artificial horizon differs somewhat from the standard instrument in that the horizon bar moves only to show bank, and the climb or glide angle is shown by movement of the miniature aircraft (Pitch Indicator).

(iii) The suction-driven gyros of these Units control the hydraulic servo-motors through pneumatic relays, the Directional Unit controlling the rudder and the other unit the ailerons and elevators.

(iv) Above the directional card there is a follow-up card which must he aligned with it before the Gyropilot is engaged. On the other instrument there is a bank follow-up pointer at the top, to be aligned with the bank indicator there, and a pitch follow-up pointer on the right-hand side, to be aligned with the line through the miniature aircraft.

(v) The pilot's controls of the gyropilot, mounted on these instruments, are:

(a) The Directional Unit caging and course-setting knob (IN TO CAGE), which is pulled out to uncage and pushed in and rotated for setting course.

(b) The Bank and Climb Unit caging knob (UNCAGE-CAGE) which is rotated for caging and uncaging.

(d) The aileron knob (AIL) which is turned to align the Bank follow-up pointers.

(e) The elevator knob (ELE), for similarly aligning the climb follow-up pointers.

(vi) In Gyropilot type A.2 there is also a level flight knob which can be turned to OFF or LEVEL. When set to LEVEL the gyropilot will hold a constant pressure altitude. There is no level flight control in type A.3.

(vii) The speed of response of the controls is regulated by three rotatable SERVO SPEED knobs marked:

RUDDER AILERON ELEVATOR and FAST-SLOW, with an indicator of its setting above each.

(viii) The Gyropilot, according to the particular installation, is engaged and disengaged by one of the following means :

(a) A single lever, controlling all three servos mechanically;

(b) A single cock, controlling all three servos hydraulically.

In addition, three cocks are provided on some aircraft, by means of which the controls may be separately disengaged by opening the corresponding cock (OFF) and turning the corresponding speed valve fully SLOW (closed).

(ix) An oil by-pass valve may also be fitted which must be ON before the Gyropilot can be brought into action. Turning this valve OFF when the Gyropilot is not in use reduces the work done by the pump and may save it from damage in the event of leaks occurring in the system.

(x) Automatic relief valves in the servo-motors permit the pilot to overpower them if necessary.

(xi) The pneumatic suction and the hydraulic pressure are shown by gauges. The suction should be between 3 and 5 inches Hg. and the hydraulic pressure should be within to lb./sq. in. of the figure specified for the particular aircraft.

2. Action and tests before flight.

(i) While warming up the engine:

(a) Uncage the gyros.

(b) Check suction and oil pressure, with the engine running between a fast tick-over and low cruising r.p.m.

(c) At r.p.m. sufficient to give these figures, and with the Speed Valves fully open, move all three controls hard over each way in turn, holding hard over 30 seconds.

NOTE.-This "bleeds" the system of air in the oil. It is especially important that the system be bled if the aircraft has been parked with the controls locked by the Gyropilot, as movement of the controls in the wind causes air to enter the system.

(d) After a few minutes running of the engine check that the readings of the Bank and Climb Unit are approximately correct for the ground attitude of the aircraft.

(e) Set the Directional Unit follow-up card and the Bank and Climb follow-up pointers. ("Take care to align the Climb pointer correctly and not with the horizon bar.) Then engage the gyropilot and check its operation of each control in turn by making small movements of the control knob. Disengage the Gyropilot.

(f) If desired, before disengaging, the pilot can also check that he can overpower the Gyropilot and that the system is free of air. Freedom from air is indicated by the feeling that the control is positively locked until sufficient force is exerted to overpower it; resiliency of feel indicates the presence of air in the oil.

(ii) During taxying out:

Make changes of direction and check that the directional gyro indicates approximately the changes made.

3. Engaging the Gyropilot in Flight.

(a) Trim the aircraft with the trimming tabs.

(b) Check :

(b) Speed Valves suitably set. (See para. 4.)

(d) With type A.2 check Level Control OFF.

(e) Engage Gyropilot slowly.

4. Adjustment of Speed Valves.

(i) If a control hunts, the Speed Valve should be turned SLOW until the hunting ceases. It should not be turned further than is necessary to stop hunting. The position at which hunting ceases should, therefore, be checked by opening the valve slightly till hunting occurs and closing again as necessary.

(ii) In rough weather the valves should be turned a little further towards SLOW (to lower numbers) to avoid any risk of the aircraft being overstrained by too vigorous operation of the controls. Be careful, however, not to close them so far that response becomes too sluggish; never close them completely, since that would lock the controls, which might move right over when the valve was reopened.

5. Periodical Retrimming.

The Gyropilot should be disengaged occasionally during a long flight or after release of bombs and the aircraft retrimmed.

6. Changing Course.

(i) Small changes of course may be made in flat turns by slowly rotating the rudder knob.

(ii) For large changes of course, bank (up to 30°) may be applied with the aileron knob and the rudder knob may then be turned at a suitable rate, keeping the lateral level central and taking off the bank as the desired course is approached.

(iii) An alternative method of making banked turns is first to cage the Directional Control Unit and then to turn the aileron knob until the desired banked turn is obtained. To resume straight flight, remove the bank by means of the aileron knob; then reset the follow-up card and uncage the Directional Unit.

7. Level Flight (Type A.2 only).

(i) Before engaging the Level Control, the aircraft must be flown level manually at the height it is wished to maintain and carefully trimmed.

Then:

(a) Set level knob to LEVEL.

(b) Wait for the elevator follow-up pointers to stop moving.

(d) Engage the Gyropilot slowly.

(ii) The Level Flight Control must be set OFF before changing altitude.

(iii) The Level Flight Control must never he used below 500 ft.

8. Operating Limitations.

(i) The two gyros should normally be uncaged on entering the cockpit and left uncaged throughout the flight. They must, however, be caged before performing aerobatics and before steep dives and steeply banked turns. The actual limits of operation of the gyros range from 40° to 55° to the vertical.

(ii) If the Gyropilot is used below 500 ft. the pilot must keep on the alert to take over control if necessary.

9. Use of the Gyropilot after Engine Failure.

(i) As power for the Gyropilot is provided by suction and hydraulic pumps driven by one of the engines, it cannot be used if this engine has seized, or with its propeller feathered. If this engine has failed but can safely be windmilled, the Gyropilot can be used with the propeller lever set to give just sufficient r.p.m. to maintain the normal suction and oil pressure.

(ii) If the Gyropilot is in control at the time of the failure, it should be disengaged, the tendency to swing being checked with the rudder - or the pilot may first throttle back the live engine, or the live engine corresponding to the failed engine in four-engine aircraft.

(iii) To engage the Gyropilot after an engine failure :

(a) If the pumps are on the dead engine adjust the r.p.m. to the minimum to give normal suction and pressure; otherwise, feather the propeller.

(b) After opening up the live engine(s) as necessary, trim the aircraft and hold it straight. If the available rudder trim is insufficient for flight with wings level, raise the wing carrying the dead engine.

(d) Set the follow-up card and pointers.

(e) Engage the Gyropilot slowly.

10. Further information.

Reference may be made to A.P. 1469B, Vol. I, Part I (Type A.2) and Part II (Type A.3).

PART III. NOTE D - NORDEN STABILISED BOMBING APPROACH EQUIPMENT

1. Description.

(i) The Norden S.B.A.E. has two gyroscope units:-(1) The (directional) Stabiliser. (2) The Flight Control (of bank and pitch).

The gyros are driven electrically and control electric servo motors. The Stabiliser controls the rudder and also causes aileron to be applied through the action of a Banking Motor. The Flight Control controls the ailerons and elevator.

(ii) The Pilot's Direction Indicator (P.D.I.) shows any departure of the aircraft from the heading of the directional gyro. It is surrounded by four tell-tale lights used in centring the control before engagement.

(iii) The pilot's controls consist of:

(a) A Master or Power Switch (linked with a dummy switch). When this switch is put on, the Flight Control Gyro and the servo motors are started. (The directional gyro is set in motion by the bomb-aimer.)

(b) Three servo-motor clutch switches to engage respectively the aileron, rudder and elevator servo motors. (These switches are prevented from being on when the Master Switch is off by the bar linking the Master Switch with the Dummy.)

(d) A Pilot-Navigator Switch for handing over directional control to the navigator.

(e) An Attitude Control, a handwheel in a fore and aft plane with an indicator of setting.

(iv) The bomb-aimer operates:

(a) The switch STAB on the Stabiliser which sets the directional gyro in motion.

(b) The switch SERVO on the Stabiliser which controls the erection of the directional gyro.

(d) The Banking Motor (excitation) Switch (if fitted).

(e) The Banking Switch which brings the Banking Motor into action when moved from CENTRE to BANK.

(f) A knurled knob, turned clockwise to engage the Secondary Clutch which connects the directional gyro to the electrical contacts which operate the rudder servo motor and the Banking Motor.

(v) There are also on the Stabiliser three knurled knobs for adjustments.

(vi) The Navigator operates: - The navigator's Precessing Switch for making turns when the Pilot-Navigator switch is set to NAVIGATOR.

2. Operation.

(i) The gyros must be started 10 minutes before the S.B.A.E. is put in control; but the Master Switch must be off during take-off.

(a) Put on Master Switch and direct bomb-aimer to put on the switch STAB. After 2 minutes the bomb-aimer will put on switch SERVO.

(b) After 8 to 10 minutes direct bomb-aimer to engage the Secondary Clutch and switch on: P.D.I. Banking Motor (if switch is fitted), and set the Banking Switch to CENTRE.

(d) Centre the P.D.I. by using the Processing Switch and engage the rudder servo-motor clutch.

(e) Level the wings until the aileron tell-tale lights (on either side of the P.D.I.) are both out or flicker alternately, and then engage the aileron servo-motor clutch.

(f) Adjust the Attitude Control in the same way by the aid of the tell-tale lights above and below the P.D.I., and engage the elevator servo-motor clutch.

(g) Direct the bomb-aimer to put the Banking Switch to BANK.

(ii) Level flight, climb or descent can be obtained by adjustment of the Attitude Control and the engine controls.

(iii) Turns are made by the pilot by use of the Precessing Switch. (The Banking Switch must be set to BANK.)

(iv) Turns can be made by the navigator by use of his Precessing Switch when the pilot's switch is set to NAVIGATOR.

(v) To cut out the control:

(a) Switch off servo motors.

(b) Direct bomb-aimer to disengage Secondary Clutch, set Banking Switch to CENTRE, and switch off: -. P.D.I. Banking Motor (if switch is fitted). STAB and SERVO.

NOTE.-In emergency, the S.B.A.E. can be cut out by putting the Master Switch off, when the connecting link will throw out the three servo-motor clutch switches.

(vi) The controls should be disengaged and the aircraft retrimmed when, owing to release of bombs or consumption of fuel, the flight conditions may have changed appreciably.

3. Miscellaneous Notes.

(i) In straight flight in bumpy air the Banking Switch may be set to CENTRE to reduce the correcting action of the controls; but it must be set to BANK for turning.

(ii) The rudder control is fitted with a dashpot with an adjustable by-pass regulated by a knurled knob with a locknut on the top of the stabiliser. This by-pass may require adjustment according to weather conditions; it should be set to reduce hunting of the P.D.I., or "weaving" of the aircraft, to a minimum; but care must be taken not to close the by-pass completely.

(iii) If a tendency to sideslip is shown on the P.D.I. the following action may .he taken. Set the Banking Switch to CENTRE and adjust the forward knurled knob on the port side of the Stabiliser until the P.D.I. (or the Stabiliser brush) is central. Put the Banking Switch to BANK and note whether the aircraft banks. If so, adjust the aft knob on the port side of the Stabiliser until no banking occurs on switching over from CENTRE to BANK.

NOTE.-Maladjustment may cause breakage of the follow-up cables, jamming of the rudder servo motor, and locking of the rudder. The adjustment in (iii) must only be undertaken by personnel who are adequately conversant with the apparatus.

4. Use of the S.B.A.E. after Engine Failure.

(i) If the S.B.A.E. is in control, at the time of failure, it should be disengaged, the tendency to swing being checked with the rudder-or the pilot may first throttle back the live engine, or the live engine corresponding to the dead engine in a four engine aircraft.

(ii) The S.B.A.E. may be engaged for flight after engine failure as follows:--

(a) After opening up the live engine(s) as necessary, trim the aircraft and hold it straight with the wing carrying the dead engine slightly raised (about 50 bank).

(b) Throttle back the live engine corresponding to the dead engine and engage the S.B.A.E. in the usual way.

(iii) As the live engine is opened up the aircraft will swing off course slightly. It may be brought back on to course by means of the Precessing Switch.

(iv) The aircraft will fly with bank and no attempt must be made to level the wings; the Banking Switch must not be put to CENTRE while the S.B.A.E. is in control.

(v) The P.D.I. will go off centre; no attempt must be made to centre the P.D.I. by adjusting the knobs on the Sector Panel.

NOTE 1.-The S.B.A.E. takes a large current and a generator must be in action if it is to be used for more than a short period. It will, therefore, be necessary to fly with the propeller of the dead engine unfeathered to maintain charge from the generator if the only generator is on this engine.

NOTE 2.-It is necessary to fly with bank on account of the limited travel of the rudder under automatic control.

PART III. NOTE E - MINNEAPOLIS-HONEYWELL AUTOMATIC PILOT (Series C.1)

1. Description.

(i) The automatic pilot has two gyroscope units:--

(1) The Stabiliser, or directional unit.

(2) The Flight Gyro, or pitch and bank unit.

The gyros are driven electrically and control electric servo motors through an electronic system. The Stabiliser controls the rudder and the Flight Gyro controls the ailerons and elevator.

(ii) A Pilot's Direction Indicator (P.D.I.) shows any departure of the aircraft from the heading of the directional gyro. It is surrounded by three pairs of tell-tale lights used in centring before engagement.

(iii) The automatic pilot is brought into action and adjusted by tumbler switches and rotatable knobs on the Pilot's Control Box:

(a) The linked Master and Stabiliser Switches set the gyros and servo motors in motion.

(b) the switch marked SERVO controls the erection of the directional gyro in the Stabiliser.

(d) The control is engaged by means of the three (central) servo motor clutch switches, for aileron, rudder and elevator control. (The bar linking the Master and Stabiliser Switches prevents these switches from being on when the Master Switch is off.)

(e) The top row of (larger) knobs are used for centring the respective systems to ensure that there will be no kick on engaging the control. The direction in which the control would be applied on engagement is shown by the tell-tale lights and the knob is turned to extinguish the lights. The elevator lights are above and below the P.D.I., the aileron lights to either side, and the rudder lights are a pair near the P.D.I. Each knob carries an adjustable pointer which should normally be up. The direction in which to turn is indicated above each knob.

(f) The nine smaller knobs are used only in adjustment of the automatic pilot to the aircraft in which it is fitted (see para. 3).

(iv) Turns are made by the pilot by means of the Turn Control. A little pressure is required to move the knob from its centre position to the scale to either side, running from 0° to 40° of bank. Movement to any position on the scale, including zero bank, locks the directional gyroscope to the aircraft, removing the automatic directional control. The pilot selects the angle of bank desired.

(v) Turns can also be made by the bomb aimer by disengaging the Secondary Clutch (by turning the knob anti-clockwise) and moving the knob to the right or left according to the direction of turn desired. The Secondary Clutch can only be moved when the Turn Control knob is at centre. The P.D.I. indicates to the pilot the direction of any turn made by the bomb aimer

2. Operation.

(i) The gyros must be started 10 minutes before the automatic pilot is put in control; but the Master Switch must be off for take-off.

(a) Check with bomb-aimer that the Secondary Clutch is engaged.

(b) Check TURN CONTROL central and pointers on centring knobs are up.

(d) After two minutes switch on P.D.I. and SERVO.

(e) Fly straight and level for 8 to 10 minutes and trim the aircraft.

(f) Centre P.D.I. by turning the aircraft and turn the rudder centring knob (central knob) as necessary so that both rudder lights are out or both flickering. Put rudder servo switch on.

(g) Level the wings and centre with the aileron knob (left) as above. Put aileron servo switch on.

(h) Adjust the fore and aft attitude and centre with the elevator knob as above. Put elevator servo switch on.

(i) The pilot can change the attitude and the lateral level of the aircraft by means of the centring knobs.

NOTE.-The centring knobs must always be moved slowly. If the tell-tale lights are objectionable at night, they may be switched off by the switch on the dashboard and the servo motors engaged with the centring pointers up, or as found best on the last flight. There may be a kick from the control on engagement.

(ii) To make turns, set the TURN CONTROL to the desired direction and degree of bank. Bank should be applied gradually by a slow, steady rotation of the knob and taken off gradually, the knob being left at zero bank until the wings are level and then returned to centre.

NOTE.-Turns must never be made at more than 30° bank in bumpy weather.

(iii) Normally the automatic pilot should be disengaged by opening the three servo switches, leaving the MASTER switch on, In emergency the three switches can be thrown off together by opening the MASTER switch.

(iv) The control should be disengaged and the aircraft retrimmed when, owing to release of bombs or consumption of fuel, the flight conditions may have changed appreciably.

3. Flight Adjustments.

NOTE.-These flight adjustments should have been made before the aircraft is put into service and. the adjustment pointers should be set so that the correct setting is with the pointers straight up. Ir should not normally be necessary for the pilot to alter these settings.

(i) The second horizontal row of knobs marked SENSITIVITY controls the response of the automatic pilot to departures in attitude and bearing. If set too sensitive, a rapid jiggling of the control will result. The sensitivity should be decreased to a point just below the setting at which this jiggling of the control occurs.

(ii) The next row marked RATIO determines the movement of the control surface which will result from a given displacement of the aircraft. If the ratios are set too high, the aircraft will hunt; if too low flight will be sloppy.

(iii) The bottom row marked TURN COMPENSATION control the amount of aileron, rudder and elevator used in making turns. These adjustments should only be made by specialists.

(iv) The rudder control has a dashpot with an adjustable by-pass regulated by a knurled knob with a locknut on the top of the stabiliser. This by-pass may require adjustment according to weather conditions and should be set to reduce hunting of the P.D.I. or "weaving" of the aircraft to a minimum, but care must he taken not to close the by-pass completely.

4. Use of the Automatic Pilot after Engine Failure.

(i) If the automatic pilot is in control at the time of failure, it should be disengaged, the tendency to swing being checked with the rudder-or the pilot may first throttle back the live engine, or the live engine corresponding to the failed engine in a four-engine aircraft.

(ii) The automatic pilot may be engaged for flight after engine failure as follows:

(a) After opening up the live engine(s) as necessary, trim the aircraft and hold it straight with the wing carrying the dead engine slightly raised (about 5° bank).

(b) Centre the P.D.I. by turning the aircraft and turn the rudder centring knob till both rudder lights are out or flickering. Put the rudder servo switch on.

(c) Keeping the wing carrying the dead engine slightly raised, centre the aileron knob as above. Put the aileron servo switch on.

(d) Adjust the attitude and centre with elevator knob. Put the elevator servo switch on.

NOTE 1.-The automatic pilot takes a large current and a generator must be in action if it is to be used for more than a short period. It will, therefore, be necessary to fly with the propeller of the dead engine unfeathered to maintain charge from the generator if the only generator is on this engine.

NOTE 2.-It is necessary to fly with bank on account of the limited travel of the rudder under automatic control.

PART III. NOTE F: - OXYGEN APPARATUS.

(Notes for all members of air crews).

1. Introductory.

(i) The rarer air at the higher altitudes supplies the human body with insufficient oxygen and the deficiency is made good by the use of oxygen apparatus.

(ii) At extreme altitudes the blood is incapable of absorbing the necessary oxygen at the low pressure obtaining and pressure cabins or suits are required. For pressure cabin aircraft the altitudes in the following instructions are to be understood as referring to the readings on the cabin altimeter.

(iii) Oxygen starvation in its early stages causes extreme self-confidence, though in fact the senses are dulled and the powers of reasoned thought and quick action are weakened. The onset of oxygen starvation is therefore insidious. The subject may become unconscious within a minute, if without oxygen at high altitudes, and with little or no warning.

(iv) Excess of oxygen has no harmful effect over any period that will occur in flight; reduction of flow to the minimum required is important only to conserve the supply to cover the duration of the flight.

(v) A greater flow of oxygen is required for abnormal bodily exertion, and oxygen should be used at lower altitudes in extreme cold or with high rates of climb.

2. Descriptive.

(i) Oxygen is carried in high pressure cylinders and the supply is turned on by opening the line valve. Oxygen is delivered at a suitable rate of flow to masks by adjustment of the delivery control in the regulators, or master regulator.

(ii) In one system a Mark VIII regulator at each station controls the flow to each member of the crew. The VIII A and C regulators contain (on the right) a dial showing the pressure in the high pressure line, measuring the OXYGEN SUPPLY AVAILABLE in the cylinders; this dial is omitted in the VIII B and D regulators used only at crew stations where the supply of oxygen available is not required to be known. The left-hand dial shows the flow of oxygen (DELIVERY) in terms of the altitude for which it is normally suited, the minimum flow reading being :

VIII A and B (used without economisers) about "5" (5,000 ft.)

VIII C and D (used with economisers) about " 10" (10,000 ft.)

The flow is controlled by turning the wing nut.

(iii) Alternatively, one master Mark X regulator is used to control the flow to all stations taking oxygen. This regulator embodies an ON-OFF valve in addition to the FLOW control, and high (OXYGEN AVAILABLE) and low pressure gauges, the latter marked in thousands of feet. The flow is metered to each station by jets in the distributing manifolds according to the altitude setting on the master regulator low pressure dial. Flow indicators at each station show when the flow is ON.

(iv) The economiser (used in later installations) saves about half the flow of oxygen by storing the flow while breath is being exhaled instead of letting it go to waste. (The delivery dials of Mk. VIII C and D regulators used with economisers require to be differently graduated in terms of altitude in relation to flow.)

(v) When economisers are not fitted, the supply at alternative stations is automatically cut off when the flexible pipe to the mask is disconnected from the bayonet socket. With economisers, the flexible pipe from the economiser at crew stations must be stowed in the cut-off valve.

NOTES :-
(a) When opening line and cylinder valves, always turn fully on.

(b) With Mk. X regulator, open line valve before turning regulator valve ON; turn OFF before closing line valve.

(c) When the supply dial indicates in the red sector the pilot .should descend below 15,000 feet. The supply should be turned off before the pointer reaches EMPTY to prevent the entry of moisture into the system.

(d) Mark VIII C and D and Mark XA regulators can be set to give more than the flow of oxygen normally required at 40,000 ft., the delivery dial then indicating in the sector marked EMERGENCY. This is for use only if a shortage of oxygen delivery is suspected.

(e) The rubber tube of Masks, type E and G, used with economisers, must not be squeezed, as this action may damage the economiser.

3. Check before Flight.

Open the line valve fully before every flight and check :

(a) that the supply is adequate for the flight;

(b) that the flow reaches the "40" mark on fully opening the regulator.

4. Use of Oxygen in Fighters.

(i) Pilots of single-seater fighters will leave the line valve fully open after checking supply and flow, except when oxygen will definitely not be required during the flight.

(ii) Oxygen will he used from ground level :

(a) When climbing to over 15,000 ft. with a rate of climb exceeding 2,000 ft. per minute.

(b) On operational flights at night.

(iii) Oxygen will be used above 10,000 ft. :

(a) If the flight is likely to last more than one hour.

(b) If the flight is at night.

Oxygen will be used in all circumstances above 15,000 ft.

(iv) The regulator will be set at least 5,000 ft. above altimeter height. If the supply of oxygen is adequate, frequent resetting may be avoided by setting the regulator to 30,000 ft. on reaching 10,000 ft.

6. Use of Oxygen in Bombers.

(i) Oxygen will be used above 10,000 ft.:

(a) If the flight is likely to last more than one hour above 10,000 ft.

(b) If the flight is at night.

Oxygen will be used in all circumstances above 15,000 ft.

(ii) With economisers :--

(a) When oxygen is required below 15,000 ft. the regulator will he set to 15,000 ft.

(b) When oxygen is required between 15,000 and 20,000 ft. the regulator will be set to 25,000 ft.

(iii) Without economisers :

When oxygen is required the regulator will be set at least 5,000 ft. above altimeter height.

(iv) At night the use of oxygen by pilots and air gunners should be continued until the aircraft has landed, to maintain maximum night vision.

6. Notes on endurance.

(i) The endurance on one full cylinder per man with one regulator per man with economisers is:

(ii) The remaining- endurance is not exactly proportional to the supply dial reading:

7. Further Information.

Reference may be made to A.P.1275 Instrument Manual, Vol. I, Section XI.

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