These notes were made by Even Larsen for the release of the Mosquito models for Microsoft Flight Simulator version 5. While they do not cover all the flying notes for the real Mosquito they do give the Flight Sim enthusiast an opportunity to fly the model in the same fashion and experience similar conditions to that enjoyed by a real Mosquito pilot.


Flying the de Havilland DH 98 Mosquito

Annotated Pilot's Notes for Mosquito FB 6.

Compiled by Even Larsen.

Introduction.

This text is based on excerpts from Pilot's Notes for Mosquito FB 6. Technical descriptions and other parts that are irrelevant to users of Microsoft Flight Simulator Version 5 (FS5 in the notes) have been omitted. I have added some comments (in italics) on the peculiarities of the FS 5 Mosquito and some comments on actual WWII practice where it seems to differ from the Pilot's Notes.



Sources.

A.P. 2019E-P.N. Pilot's Notes for Mosquito FB 6.
British Air Ministry, January 1950.

Flying the D.H. Mosquito by Flt. Lt. L.P. Hanson-Lester.
The Aeroplane, June 29, 1945.

Mosquito Fighter-Bombers.
Flight, September 7, 1944.

Confound and Destroy - 100 Group and the Bomber Support Campaign by Martin Streetly.
Macdonald and Jane's Publishers, 1978.


PILOT'S CHECK LIST.

Items 1 - 51 are external and internal checks of the aircraft.

Cockpit checks.
Item. Check.
52 Elevator Trimmer. Full and correct movement.
58 Boost Guages. Static reading.
68 Ignition switches. Off.
75 Navigation lights. Operation.
86 Radio. Test. Check altimeter setting with control.
89 Direction indicator. Set with magnetic compass.
Exercise and test the engines.


Checks before and during taxying.
Item. Check.
94 Taxying. As soon as possible test brakes.
Direction indicator for accuracy.
Artificial horizon for accuracy.
Temperatures and pressures.


Checks before take-off.
Item. Check.
95 Trim. Elevator: Slightly nose heavy.
Rudder: Slightly right.
Aileron: Neutral.
97 Rpm controllers. Maximum rpm position.
98 Fuel. Contents. Correct tanks selected.
99 Flaps. Up or 15° down
102 Direction indicator. Synchronised with magnetic compass.


Checks before landing.
Item. Check.
108 Fuel. Fullest tanks selected.
Reduce speed to 155 knots and check:
110 Undercarriage. Down and locked. Green lights on.
111 Rpm control levers. Set to give 2850 rpm.
Reduce speed to 130 knots.
112 Flaps. As required.


Checks after landing.
Item. Check.
113 Flaps. Up. Selector neutral.
115 Rpm control levers. Maximum rpm position.


On reaching dispersal.
Item. Check.
118 Ignition switches. Off.
122 Fuel Cocks. Off.



PART 1 - DESCRIPTIVE.

Introduction.

The Mosquito FB Mark 6 is a fighter-bomber aircraft and is powered by two Merlin 23 or 25 engines, driving three-bladed, Hydromatic propellers. There is provison 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.

Fuel and oil systems.

1. Fuel Tanks.
Fuel is carried in four outer tanks, four inner wing tanks, and two centre tanks.

Fuel capacities are as follows:
Main supply. Centre tanks. 50 gallons.
Inner wing tanks. 286 gallons.
Outer tanks. 116 gallons.
Total. 452 gallons.


The fuel capacities are given in Imperial gallons. FS5 measures in US gallons so you will see larger numbers in the Engine and Fuel dialogs.
The auxilliary tanks in FS5 represent the Outer tanks (140 US gal) and the Main tanks represent the Mosquito's Main supply (406 US gal) for a total fuel capacity of 546 US gal.
In the real Mosquito you can switch between Main supply and Outer tanks but you cannot use both at the same time. While the Main supply can feed both engines the starboard outer tanks will only feed the starboard engine and the port tank the port engine.
If one engine fails fuel left in the corresponding outer tank cannot be used so the outer tanks should be emptied first.

Aircraft controls.

11. Flying controls.
The flying controls are conventional and the rudder pedals are adjustable for reach.

18. Flaps control and indicator.
Operation of the flaps is controlled by the lever marked F to the right of the undercarriage selector lever.

19. Wheel brakes.
The brakes control lever and parking catch are on the control column. Differential braking is afforded by means of a relay valve connected to the rudder pedals.

Engine controls

20. Throttle controls.
Normally the throttles can be pushed forward to the stops only. When the small catches on the levers are squeezed the throttles can be pushed fully forward. Merlin 25 engines give +12 lb/in² boost at the stop and +18 lb/in² when fully forward. Merlin 23 engines may still be fitted. They give +9lb/in² at the stops and +12 lb/in² at the fully forward position.

The MS Flight Simulator FB6 model has Merlin 23 engines. Unfortunately FS5 and Apollo's Flight Shop do not model supercharged engines. You will never see the manifold pressure increase beyond outside barometric pressure no matter how far forward you push the throttle. You will lose too much power at altitude and there is nothing I can do about it.

21. Mixture and slow running cut-out controls.
The real Mosquito has automatic mixture controls.
To stop the engines cut the fuel supply.

22. Propeller controls.
The rpm control levers which vary the governed pitch from 3000-1800 rpm are fitted on the side of the engine control box.

PART II - HANDLING.

36. Management of the fuel system.
Start the engines on the outer tanks, warm up on the main tanks, taxy and take-off on the fullest tanks.

40. Take-off.
(i) Carry out items (95) to (105) in the Pilot's Check List.
(ii) Taxy forward a few yards to straighten the tailwheel.
(iii) Open the throttles slowly, checking any tendency to swing by coarse use of the rudder and by differential throttle movement. There is little tendency to swing if the engines are kept synchronised. The travel of the throttle levers is very short for the power obtained. Coarse use of the throttles will aggravate any tendency to swing.
(iv) When comfortably airborne, brake the wheels and raise the undercarriage.
(v) Safety speed at a weight of approximately 17000lb flaps up or 15° down at +9 lb/in² boost is 155 knots. At +18 lb/in² it is 170 knots. These speeds however, may vary considerably with individual aircraft.
(vi) Before raising the flaps, if used, trim the aircraft slightly tail heavy.

Don't bother with differential throttle. Open the throtle slowly and use a little right rudder. You do not need full power to take off from a decent length runway. In any circumstances don't open the throttle fully before the tail has come up. The usual practice was to take off at about 100 knots, with 15° flaps, because it lowered the single engine safety speed. Climb slowly until safety speed has been reached.

41. Climbing.
(i) The speed for maximum rate of climb is 150 knots.
(ii) Climb in low gear at 2850 rpm and +9 lb/in² boost. When the maximum obtainable boost has fallen to +7 lb/in², change to AUTO. Above 18000 ft decrease the airspeed by 2 knots per 1000 ft.
(iii) When climbing for maximum range, climb in low gear at 2650 rpm and +7 lb/in² boost, using the airspeeds recommended above. When the maximum obtainable boost has fallen to +4 lb/in² set the supercharger gear change switch to AUTO and re-adjust the throttles. Above 18000 ft increase power to +9 lb/in² and 2850 rpm and reduce airspeed as recommended. Although less fuel is used to reach a given altitude by climbing at high power the total fuel used and the time taken on the subsequent cruise is the same, whether the aircraft is climbed at 2650 rpm ans +7 lb/in² or 2850 rpm and +9 lb/in² boost.

The supercharger stuff and boost settings don't apply to the FS 5 model but you can still climb at the quoted indicated speeds and rpm settings.

42. General flying.
(i) Stability. Stability about all axes is satisfactory, but with the CG aft longitudinal stability deteriorates on the climb.
(ii) Changes of trim.
Undercarriage up. Slightly nose up.
Undercarriage down. Nose down.
Flaps up. Strongly nose down.
Flaps down. Nose up.
Radiator shutters open. Nose up.
Radiator shutters closed. Nose down.
Bomb doors open. Nose up slightly.
Bomb doors closed. Nose down slightly.

The radiator shutters and bomb doors are not modelled in FS 5.

(iii) Controls. The controls are light and effective and manæuverability is good. The rudder should not be used violently at high speeds. When two-tier R.P. or rails are carried, aileron control is poor at low speeds, ie., during take-off and approach to land.
(iv) Flying at reduced airspeeds. Speed should be reduced to 175 knots, flaps lowered 15° and the rpm controls set to give 2650 rpm. Speed may then be reduced to 130 knots.

43. Stalling.
(i) The approximate stalling speeds in knots are as follows:
Power off. 1800lb.
Undercarriage and flaps up. 105
Undercarriage and flaps down. 95-100
Power on under typical approach conditions. 90-95
(ii) Warning of the approach of the stall is given by the pronounced buffeting of the control surfaces, the onset of which can be felt some 10 knots before the stall itself. At the stall the aircraft pitches, the ASI fluctuates and the nose drops gently. There is little tendency for the wing to drop unless the control column is held back. Recovery is easy and normal in all cases.

44. Cruising.
(i) For any required airspeed, the maximum weak mixture boost (+7 lb/in²) together with the lowest practicable rpm provide the most economical conditions.
(ii) When cruising at low rpm the engines should be cleaned every 30 mins. at +12 lb/in² boost and 2850 rpm for 30 secs.
(iii) At any height the speed for maximum range is 170 knots at a weight of 17000 lb. but below 10000 ft this speed can only be obtained at an uneconomical boost setting, even when using minimum rpm. Speed should therefore be increased to approximately 200 knots.

47. Approach and landing.
(i) Carry out items 106 to 112 in the Pilot's Check List.
(ii) From 17000 lb. to 18000 lb. the following final approach speeds are recommended:
Flaps down.
Engine assisted.   100-105 knots.
At full load this speed should be increased by about 5 knots.
(iii) With undercarriage and flaps down the rate of descent is very high. If undershooting, corrective action entails the use of more power than might be expected.
(iv) After landing and when clear of the runway carry out items 113 to 117 in the Pilot's Check List.

According to our sources the usual practice was to reduce speed to about 155 knots and lower the undercarriage on the downwind leg. Power was added as necessary for level flight at 140 knots.
On crosswind the flaps were lowered and speed reduced to 125-130 knots. (Some pilots applied full flaps at once, some used 30° flaps on crosswind and full flaps on final). A speed of 125 knots was maintained on final approach because it was needed in case of engine failure. The throttle was cut at the threshold, reducing speed to about 100 knots at touchdown.

48. Mislanding and going round again.
The aircraft will climb satisfactorily at approximately 120 knots with flaps and undercarriage down at climbing power.
(i) Open the throttles to +9 lb/in²: boost.
(ii) Raise the undercarriage and while it is retracting raise the flaps to 15°, and re-trim.
(iii) At a safe height and speed retract the flaps fully and re-trim.


PART III - LIMITATIONS.

51. Engine data Merlin 23 and 25.
The principal engine limitations are as follows for Merlin 25.
Rpm Boost lb/in² Oil Temp C° Restrictions.
Max take-off. 3000 +18
Intermediate. 2850 +9 90 1 hour limit.
Maximum. 2650 +7 90 continuous.
Operational necessity. 3000 +18 105 5 mins. limit.
Minimum oil pressure. 30 lb/in²
Minimum oil temp for take-off. +15°C.
The limits for Merlin 23 are similar except maximum obtainable boost is +14 lb/in²

52. Flying limitations.
(i) Deliberate spinning is prohibited and an incipient spin should be checked by immediate recovery action.
(ii) The controls are light and effective and care should be taken to avoid excessive accelerations in turns and recovery from dives. At high speeds violent use of the rudder and large angles of yaw must be avoided.
(iii) Maximum weights.
Take-off and gentle manæuvers. 20500 lb.
All forms of flying. 19000 lb.
Landing. 20500 lb.

(iv) Maximum speeds in knots are; (Without underwing stores)
Sea level to 10000 ft. 370
10000 ft to 15000 ft. 350
15000 ft to 20000 ft. 320
20000 ft to 25000 ft. 295
25000 ft to 30000 ft. 260
30000 ft to 35000 ft. 235
Bomb doors open. 305
Undercarriage down. 155
Flaps not more than 25° down. 175
Flaps fully down. 130


PART IV - EMERGENCIES.

55. Engine failure during take-off.
(i) The handling characteristics of individual aircraft differ considerably according to age and load. Except in cases where it is known to be less; at approximately 17000lb safety speed should be assumed to be 155 knots at +9 lb/in² boost and 170 knots at +18 lb/in² boost.
(ii) If safety speed has been attained, the aircraft will climb safely away on one engine at climbing power at about 135-140 knots provided that
   (a) The propeller of the failed engine is feathered and the radiator shutter closed.
   (b) The flaps are fully up.
(iii) The drag of a windmilling propeller is very high and unless feathering action is taken immediately, control can only be maintained at the expense of a rapid loss in height.
(iv) The aircraft accelerates slowly to the safety speed at +18 lb/in² boost. If high power is used for take-off it is recommended that climbing power is used as soon after take-off as is possible.

56. Engine failure in flight.
(i) Close the throttle and feather the propeller of the failed engine.

You can't feather the propeller in FS 5. Pull the rpm lever of the failed engine all the way back. This will reduce rpm of the failed engine considerably. I don't know whether FS 5 models windmilling propeller drag.

(iii) At full load, height can be maintained on either engine up to 12000 ft using climbing power at about 150 knots.

57. Single-engine landing.
(i) While manæuvaring with the flaps and undercarriage up a speed of 140-150 knots should be maintained.
(ii) A normal circuit can safely be made irrespective of which engine has failed. The checks before landing should be carried out as for a normal landing, but it should be remembered that the undercarriage will take longer to lower on one engine and, owing to it's high drag, height will be lost once it has started to lower.
(iii) When across the wind flaps may be lowered 15° and the live engine used carefully to regulate the rate of descent. Speed should not be allowed to fall below 135 knots until it is clear that the airfield in within easy reach; flaps may then be lowered further as required and power and speed reduced as height is lost, aiming to cross the airfield boundary at the speeds quoted for an engine assisted landing.

58. Going round again on one engine.
Going round again is only possible if the decision is made while ample height remains and before more than 15° of flap is lowered. The height is required in order to maintain the speed above the critical speed, for the high power necessary, while the undercarriage and flaps are retracting.

Raising the flaps and undercarriage with a failed engine takes the same time as usual in FS 5, so you will have a greater safety margin than a real Mosquito pilot.

When the decision to go around again has been made:
(i) Ensure that the speed is not less than 135 knots, and then increase power on the live engine to +9 lb/in² boost and 2850 rpm.
(ii) Raise the undercarriage.
(iii) Increase speed to 140-150 knots.
(iv) Raise the flaps and re-trim.
(v) Power higher than +9 lb/in² should only be applied carefully and within the limits of rudder control.

60. Flapless landing.
The approach with flaps up is very flat, and difficulty may be experienced in maintaining a steady airspeed. At the maximum landing weight the final approach should be made at 115 knots. At light loads this speed may be reduced by 5 knots. The touchdown is straightforward and the landing run, although lengthened does not become excessive.



Mosquito History    Mosquito Variants    Tsetse Mosquito    100 Bomber Group

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