Harold Wakefield's notebook

Harold Wakefield's notebook

Notes on theory of flight, thermodynamics, power calculations, engines and components, superchargers, propellers, range flying, velocity/speed calculations, rules for range flying, flight planning, electronic circuits and electrical theory.

1945-07-13

Printed notebook with handwritten notes

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MWakefieldHE174040-171016-08

Transcriber Alan Pinchbeck
Web address of item or file identifier(s) MWakefieldHE174040-171016-08
Date completed 21/01/2024 (SB 07/03/2024)
Notes to reviewer (if any)
IBCC Digital Archive – Transcriber Worksheet

Transcription:

F/O H.E. WAKEFIELD F/E No. 13 COURSE
1332 H.C.U.
13/7/45

ROYAL AIR FORCE

Notebook for use in Schools.

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[blank page]

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[3 sketches]

Decrease in speed gives increase in pressure } or vice versa.
Increase in speed gives decrease in pressure } or vice versa.
Lift is 20 times the drag } approx.
Lift & fuselage etc. is 10 times drag } approx.
Optimum Angle of Attack = That angle of attack which gives greatest lift with minimum drag.
Speed & Angle of Attack considered in efficient results.

[sketch]

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SINGLE ENG. LAND.

[sketch]

[underlined] Absolute Ceiling [/underlined] is the max. height obtainable in a standard atmosphere under specified conditions.
[underlined] Service Ceiling [/underlined] is the height at which the rate of climb has fallen to 100ft. per minute.

[page break]

B.T.H.U. British Thermal Unit
The power to raise 1lb of water 1° F.
1 gal. of petrol contains 14000 to 20000 B.T.H.U
1 B.T.H.U. = 778 ft. lbs.

100% Heat Generated.

[sketch]

Thermal Efficiency = Output/Input x 100/1
Indicated Th. Eff. = Heat converted into work in cyl./Heat input x 100/1
Brake Th. Eff. = Heat converted into work at crankshaft/Heat input x 100/1
Fuel H.P. = Consump (lbs. per min) x Cal. Val. x 778/33000
Find fuel h.p. of engine consuming 10lbs per min when Cal Val = 19000 BTHUs?
[deleted] 33000 [/deleted] Work energy required to [inserted] lift [/inserted] 1lb 1ft in 1 min - 33000ft. lbs. per min = 1 H.P.

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An engine develops 1200 H.P. at 22000 ft. If it consumes fuel at 10 lbs. per min. calculated its Thermal Efficiency.
(Cal. Val. of fuel = 19.800 B.T.H.U.)

H.P. for cylinder. = P.L.A.N./33000

P = M.E.P.
L = length for Stroke
A = Area of piston
N = no. of power strokes
R.P.M./2

B.H.P. = 2 [symbol] TN/33,000 T = torque N = no. of power strokes per min.

Frictional H.P. = 1. H.P. - B.H.P.
Mech. Eff = B.H.P./1.H.P. X 100/1

[calculations]

[page break]

[calculations]

Comp. Ratio = Swept Volume + Clearance Volume/Clearance Volume.

[underlined] Carburetters :- [sic] [/underlined] S.R Rich 9 : 1 } Condensation in induction system. Cold induction system, [indecipherable word] scavenging giving weakening of [indecipherable word] in cyl. Diffuser gives correct strength for cruising only.
Cruising. Weak 16 : 1 } Diffuser gives correct strength for cruising only.
Climb Rich 12 : 1 } Diffuser gives correct strength for cruising only.
T.O. Rich 10 : 1 } Diffuser gives correct strength for cruising only.

[underlined] Prevents Icing by :- [/underlined] { Coolant round jacket
[underlined] Prevents Icing by :- [/underlined] { Hot oil through butterfly
[underlined] Prevents Icing by :- [/underlined] { Fuel entry above butterfly
[underlined] Prevents Icing by :- [/underlined] { Hot air.
[underlined] Prevents Icing by :- [/underlined] { Small plates on air intake.

[underlined] Has to give [/underlined] :- { Correct mixture strength at all eng. conditions
[underlined] Has to give [/underlined] :- { Atomise the fuel
[underlined] Has to give [/underlined] :- { Fully Automatic
[underlined] Has to give [/underlined] :- { Overcome flat spot

[2 sketches]

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[sketch]

Altitude Control gives correct constant mixture strenght [sic] up to all altitudes.
Boost Control gives richer mixture for increased boost.

[underlined] Balance Duct [/underlined] [deleted] communicates [/deleted] gives constant pressure difference between choke & float chamber at all altitudes. S.U. is Variable Jet System.
[underlined] Boost Reversal [/underlined] Exhaust gases going out through inlet valves.
[underlined] Boost Bias [/underlined] prevents this by giving slight boost pressure to conteract [sic] high exhaust gas pressure.

[underlined] Supercharger :- [/underlined]

Increased power at sea - level
Maintain sea - level power up to a certain altitude
[underlined] Rated Boost [/underlined] is boost at which engine can be run under International Figures.
[underlined] Rated Altitude [/underlined] Highest alt to which R.B. can be maintained
[underlined] H.P. increases at Alt with supercharger [/underlined] due to better scavenging, (less back pressure) less back pressure in crankcase.
Cooler charge.

[page break]

[underlined] Propellers [/underlined]
[underlined] Pitch [/underlined] Is then distance the airscrew would move forward in one revolution assuming the air to be a solid body
[underlined] Slip [/underlined] = [symbol] of attack
Advance per Rev = Practical distance moved in one revolution.
[underlined] States of Compressability [sic] [/underlined] layers of air formed in front of blade
[underlined] Cavitation [/underlined] vacuum at rear of blade. (When blade is travelling at over 90% of speed of sound) Speed of sound 746 m.p.h.
[underlined] A blade has a varying [symbol] along its length to equalise the load [/underlined]

[underlined] Centrifugal Turning Moment, [/underlined] tendancy [sic] for a free propeller blade to turn to a fine pitch when rotating. [sketch]

[underlined] RANGE FLYING [/underlined]

[formulae]

L = Lift in lbs.
D = Drag in lbs.
S = Max. Plan projected area in square feet
(RHO) P = Density od Atmosphere
V = Velocity of undisturbed airflow in feet per second.

[3 graphs]

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[calculations]

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1 Nautical Mile = [underlined] 6080 [/underlined]
1 Statute Mile = 5280

1 [deleted] Statute [/deleted] [inserted] Nautical [/inserted] Mile = 33/38 = 1.15 [deleted] Nautical [/deleted] [inserted] Statute [/inserted] Miles

[calculations]

1 [deleted] Nautical [/deleted] [inserted] Statute [/inserted] Mile = 33/38 = .868 Nautical Mile.

Power Required At Altitude = Power Required at S.L. / [symbol] Relative Air Density

Power at Sea-Level = 650 B.H.P.
Find power at 10,000’ given that [symbol] Rel. Density = .8594

[calculations]

[page break]

[underlined] Rules for Range Flying. [/underlined]

Reduce I.A.S. by 1/4 the % of the % reduction in weight Max. boost min revs gives full throttle, less h.p. to drive supercharger less frictional losses.
If I.A.S. is to [sic] high with min. revs climb higher until I.A.S drops off.
Take off in rich mixture climb & get to height quickly as possible. Lose height at no more than 300 ft. per minute.
[underlined] Max range climb [/underlined] climb at recommended cruising I.A.S. using boost obtainable in weak mixture, select R.P.M. to give rate of climb desired
[underlined] Max Rate of Climb in Weak mixture, [/underlined] use max. boost obtainable & I.A.S. approaching that for rich mixture climb.
[underlined] Cruising [/underlined] cruise at optimum altitude selecting R.P.M. to give recommended I.A.S. It is usually better to climb slightly above opt. height & descend to it letting I.A.S. increase slightly finally bringing it back to recommended by R.P.M.
[underlined] Power Descents [/underlined] Use max. boost obtainable in weak mixture, maintain recommended I.A.S. & control rate of descent by R.P.M. levers & altitude. When min. R.P.M. is reached then allow airspeed to increase up to about 10 m.p.h. thereafter reduce boost (regulation rate of descent 300 ft. per min.)
[underlined] Hot & Cold Air. [/underlined] if warm air is used we lose boost due to a) loss of ram effect b) increase in inlet air temp.

[page break]

Use warm air only if (a cold air intake is blocked due to icing or foreign matter) b) when descending if carburettor icing occurs
Gills if fitted or rad shutters. Reduction of drag (parasite drag) by closing all apertures & streamlining or protuberences [sic] will mean that less B.H.P. is required to maintain a given speed better A.M.P.G. figure will be obtained if gills are closed. If cyl. head or coolant temp rise to a figure approaching max. permissable [sic] during cruising due possible to high outside or an enforced low altitude it is advisable to increase I.A.S. up to approx 6% rather than to open gills. If temp continues to rise then open gills.
During economical climb cyl. temps. Should be controlled by altitude (I.A.S.) & not by the use of gills.
[underlined] High & Low Supercharger [/underlined] [indecipherable word] never use S if can obtained power in M.
[underlined] Head Wind [/underlined] Under 30 mph. no change in speed, increase I.A.S. 4% for increase of every 10 mph. over 30 mph
[underlined] Optimum Altitude [/underlined] on a given trip over a reasonable distance if the flight is at [inserted] any [/inserted] F.T. height the total fuel used will be approx. the same. The fuel used on a weak mixt. climb will be made up by that saved on power descent.
[underlined] Economic Ceiling [/underlined] this is a max. height at which cruising power can be obtained in weak mixture & M. gear. This height varies with the A.U.W. (when rate of climb drops to 50 ft. per min at cruising I.A.S. in weak mixt. = Economic ceiling) 4% decrease or increase ceiling alters 2500 ft.
[underlined] Automatic Pilot [/underlined] as much as possible.

[page break]

For Short Distances, fly at constant revs.
For Medium Distances, fly at constant I.A.S.
For extreme Distances, fly at extreme range conditions.

[underlined] FLIGHT PLANNING [/underlined]
Factors affecting the flight plan:-
Type of load being carried & destination.
Whether flying under one of the following conditions:-
in a given time carrying max. Payload
flying at leisure carrying max. payload
or is it possible to make a certain destination carrying a given load.
flying under weight a short distance.
3) Terrestrial topography.
4) Met. Forecast.
5) Alternative landing grounds if there is a possibility of destination aerodrome being unusable.
6) Max. take off & landing weights of various staging posts en route. (possibility of jettisoning cargo)
7) Handling of the a/c - I.A.S. altitude, bearings, etc.
8) Handling engs.
9) Basic weight of A/C with essential equipment al etc.
10) Fuel required & payload.

Transport fuel safety margin 25% extra

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[sketches]

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[sketch]

[calculations]

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[calculations]

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[sketch]

[calculations]

[underlined] Flemings R. Hand Rule [/underlined]
Point the thumb in direction of motion of conduction, point the first finger in the directions of the lines of force. Hold the second finger at [indecipherable] [symbol] to the first finger then second finger will indicate the direction of current.

[underlined] Wheatstone Bridge - [/underlined] is an electrical balance [formula] for measuring a voltage difference when the resistance is thrown off balance.

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[sketches]

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[blank page]

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[sketch]

ATOM OF HELIUM

ELECTRON
[circled N] NEUTRON
[circled +] PROTON

[underlined] ohm’s Law [/underlined] In any conductor at a uniform temperature the current is directly proportional to the potential difference between its end, & inversely proportional to the resistance.

[calculations]

746 Watts = 1 Elec. HP.
Power = Volts x Amperes
Power = Watts
Board of Trade Unit = 1 Kilowat [sic] Hour

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