Aviation of WWII
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Pilot`s Notes Mosquito Pilot`s Notes


A.P. 2019E-P.N.

British Air Ministry, January 1950


Note.—Throughout this publication the following conventions apply:—

(a) The numbers quoted in brackets after items in the text, refer to the illustrations in Part V.

(b) Unless otherwise stated, all speeds quoted are indicated airspeeds.

(c) Words in capital letters indicate the actual markings on the controls concerned.


The Mosquito HB Mark 6 is a fighter-bomber aircraft and is powered by two Merlin 23 or 25 engines, driving three-bladcd. Hydromatic propellers. There is provision for the alternative carriage of a long-range tank, a bomb or depth charge, or for the simultaneous carriage of R.P. and a 100-gallon drop tank under each wing. An internal bomb load can also be carried.


1. Fuel tanks

Fuel is carried in four outer wing tanks, four inner wing tanks, and two centre tanks. In addition a fuselage (long-range) tank can be carried and a drop tank fitted under each wing.

The fuel capacities are as follows :—


Centre tanks ......... 50 gallons*

Inner wing tanks......... 286 gallons

OUTER TANKS ......... 116 gallons

Total ... ... ... ... ... 452 gallons

Long-range tank ......... 63 gallons

Wing drop tanks (2 x 100 gallons) ......... 200 gallons

Total fuel capacity ......... 715 gallons

The centre tanks and the inner wing tanks supply both engines through a fuel collector box when the fuel cocks, behind the pilot's scat, are set to MAIN SUPPLY. If a long-range lank is fitted this also supplies both engines through the fuel collector box with the fuel cocks at MAIN SUPPLY and the immersed fuel pump switch (65) on the electrical panel in the "ON" position. When the fuel cocks are set to OUTER TANKS the port outer wing tanks supply No. 1 engine only and the starboard outer wing tanks No. 2 engine only. Fuel is transferred from the wing drop tanks to the OUTER TANKS by air pressure from the port vacuum pump controlled by a transfer cock behind ihe pilot's seat. If the transfer is not automatic this cock is marked JETTISON TANKS FUEL TRANSFER : in this case the outer tanks must be nearly emptied before transferring, or fuel will be lost by venting to atmosphere. If Mod. 613 is incorporated, the cock is marked ON FOR AUTO TRANSFER and it may be left on whilst using fuel from the outer tanks. Transfer will then be automatic until the wing drop tanks are empty when the gauge will show a fall in the contents of their respective outer tanks.

A premature fall, in the early part of a flight at altitude, will indicate an interruption of flow : after an interval which will vary with atmospheric conditions, this will be cured and the fall in the fuel level will stop. The cock should be left ON during an interruption of flow, but must be turned OFF on completion of transfer.

2. Fuel tank pressurising

(i) The permanent tanks of the MAIN SUPPLY are provided with automatically regulated pressurising to reduce fuel vaporisation at high altitudes. When the PRESSURE VENTING cock, behind the pilot's scat is ON an aneroid operated valve so cont/ols pressure from the starboard vacuum pump that whilst none is admitted at low altitudes, the amount is progressively increased as height is gained. When it is OFF. all tanks are vented to atmosphere at all altitudes.

(ii) When Mod. 443 is incorporated the pressure venting cock is usually wired in the ON position because the pressurising is then extended to the long-range tank. When this modification has not been incorporated it is advisable to turn the cock OFF whilst actually using the long-range tank because the immersed fuel pump might not be able to overcome pressurising in the fuel collector box sufficiently to ensure a supply of fuel from the long-range tank.

(iii) Pressurising impairs the self-scaling properties of the tanks and should be turned OFF in emergency. If the cock is locked ON the locking wire can easily be broken.

3. Immersed fad pump

When the long-range tank is fitted an immersed fuel booster pump is provided to feed the fuel to the engine via the collector box. A fuel pressure warning light (21) on the starboard side of the front cockpit coaming, indicates when the long-range tank is nearly empty : the immersed fuel pump switch must then be turned to OFF.

4. Fad contents gauges

Three gauges (71. 72. 73) are positioned on the electrical panel. They will indicate as follows when the electrical services switch (20). linked with the ignition switches, is on.

The aft gauge (71) .. the outer wing tanks

The centre gauge (72)... the centre tanks and long-range tank when fitted

The forward gauge (73) ..the inner wing tanks

5. Fuel pressure warning lights

Two fuel pressure warning lights (5) are fitted on the left-hand side of the instrument panel. They light when the pressure drops to 3 lb./sq.in. (These lights will be deleted by Mod. 1243.)

6. Priming system

A priming pump is fitted in each engine nacelle and is accessible through a hinged flap on the starboard side. Priming cocks are fitted in each nacelle, and allow fuel to be drawn cither from the outer tanks, or from an external supply of high-volatility fuel for cold weather starting.

7 Oil and coolant systems

(i) Oil is supplied from two self-sealing tanks of 15 gallons oil capacity and 2½ gallons air space ; one in each engine nacelle.

(ii) There are no separate oil cooler controls. Electro-pneumatically operated radiator shutters are fitted at the rear of the combined engine coolani radiator and oil cooler, inboard of each engine. Airflow through the radiator ducts is controlled by these shutters which are operated by two-way switches (15) marked RAD. FLAP-CLOSED (up)—OPEN (down). Thermostatic and viscosity valves in both coolant and oil cooler systems respectively, ensure rapid "warming up" to predetermined temperatures.


8. Hydraulic system

(i) Two engine-driven pumps, one on each engine, supply hydraulic pressure for the operation of the :—

Undercarriage and tailwheel


Bomb doors.

The system will function on one pump, but only at a reduced rate.

(ii) A handpump for operating all the services through the normal system, when the engine pumps arc not running is mounted in a socket (55) beneath the pilot's seat. The detachable handle is stowed on the cockpit door. The approximate time to lower the undercarriage by hand-pump is four minutes.

(iii) The handpump may also be used to operate the separate emergency undercarriage lowering system, when the emergency selector valve, marked PUSH FOR EMERGENCY, on the right of the pilot's seat is pushed down.

9. Pneumatic system

(i) An air compressor on No. 1 engine charges an air bottle for the operation of the brakes and guns, and the electro-pneumatic rams for:—

Radiator shutters

Automatic supercharger gear change

Carburettor air-intake filter control.

(ii) The available pressure is shown on I he pneumatic system and brakes triple pressure gauge (36) and should record 200 lb./su. in. in flight. All services except the brakes arc cut oft by a pressure maintaining valve if the supply falls below 150 Ib./sq. in.

(iii) Two vacuum pumps, one driven by each engine, together operate the flight instruments. If either pump should fail it is automatically isolated from the suction system. Each pump can be proved on the ground by alternatively starting the port and starboard engine first and checking tbat the artificial horizon erects properly.

10. Electrical system

A generator on No. 2 engine charges a battery which supplies electrical power at 24 volts for:—

Automatic superchargers

Air intake filters

Radiator shutters


Radio (Gee 11, G.P. H.F. communication set. V.H.F., I.F.F.)

Instrument and cockpit lighting

Air recognition, identification, navigation lights and landing lamp.

Engine starters and booster coils

Immersed fuel pump

Feathering pump motors

Undercarriage warning lights and horn

Oil dilution valves

Fuel pressure warning lights


Windscreen wiper

Pressure-head heater


Reflector gunsight

Bomb selection, fuzing and release gear

R.P. release.

A warning light (60) on the electrical panel shows when the generator is not delivering current. On the ground with the engine stopped, the light will be on so long as the aircraft battery is connected. The current consumed is negligible.

A ground starter battery socket is provided on the port side of rear fuselage.

* The fuel capacities are given in Imperial gallons.

- 1 Imperial gallon=4.546 L ; 1 US gallon=3.785 L