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weight and performance calculations for the De Havilland D.H.106 Comet 4
Malaysia-Singapore Airlines Comet 4 at Kai Tak Airport in 1966
De Havilland D.H.106 Comet 4
role : jet airliner
importance : ****
first flight : 27 April 1958 operational : 4 October 1958 (BOAC route LHR – JFK)
country : United-Kingdom
design :
production : 76 aircraft > Comet 4, 4B, 4C between 1958 and 1964
general information :
After the disasters with the Comet 1's, a major investigation was launched into the causes. The result was that cracks had occurred in the cabin as a result of metal fatigue due to repeated pressure on each flight. No culprit was identified, the technological knowledge was not yet available when the Comet 1 was designed ; this problem could not have been foreseen it was judged.
With this knowledge, De Havilland decided to release a new improved version, this became the Comet 4. It could carry more passengers and had a longer range. BOAC had great confidence in it and immediately ordered 19 pieces in March 1955, followed by an order for 14 by Capital Airlines in July 1956.
The base price of a new Comet 4 was roughly £1.14 million (£24.81 million in 2019).
The Comet 4 enabled BOAC to inaugurate the first regular jet-powered transatlantic services on 4 October 1958 between London and New York (albeit still requiring a fuel stop at Gander International Airport , Newfoundland, on westward North Atlantic crossings). While BOAC gained publicity as the first to provide transatlantic jet service, by the end of the month rival Pan American World Airways was flying the Boeing 707 on the New York-Paris route, with a fuel stop at Gander in both directions, and in 1960 began flying Douglas DC-8's on its transatlantic routes as well. The American jets were larger, faster, longer-ranged and more cost-effective than the Comet. After analysing route structures for the Comet, BOAC reluctantly cast-about for a successor, and in 1956 entered into an agreement with Boeing to purchase the 707.
BEA Come 4B arriving at Berlin Tempelhof in 1969 with flaps fully extended.
The Comet 4A ordered by Capital Airlines was instead built for BEA as the Comet 4B, with a further fuselage stretch of 38 in (970 mm) and seating for 99 passengers. The first Comet 4B flew on 27 June 1959 and BEA began Tel Aviv to London-Heathrow services on 1 April 1960. Olympic Airways was the only other customer to order the type. It had shorter wings and higher capacity for a shorter range.
primary users :
Comet 4 : BOAC(19), Aerolineas Argentinas(6), East African Airways(3),
Capital Airlines was taken over by United and their order cancelled.
Comet 4B : BEA (14) Olympic Airways (4)
flight crew : 4 cabin crew : 2 passengers : 56 (2+2 layout, 3-class), 109 high density (2+3 layout, 1 class)
flight crew consist of pilot, co-pilot, navigator and flight engineer
engine : 4 Rolls Royce Avon 524 turbojet engines of 47.0 [KN](10565.8 [lbf])
dimensions :
wingspan : 35.05 [m], length : 33.99 [m], height : 8.99 [m]
wing area : 197.0 [m^2]
weights :
max.take-off weight : 73480 [kg]
empty weight operational : 34210 [kg] useful load : 9200 [kg]
performance :
maximum continuous speed : 840 [km/u] op 10700 [m]
normal cruise speed : 805 [km/u] op 10700 [m] (23 [%] power)
service ceiling : 13000 [m]
range with max fuel : 5190 [km] and allowance for 588.8 [km] diversion and 30 [min] hold
description :
low-wing cantilever monoplane with retractable landing gear with nose wheel
tapered multi-cellular wing with flush-riveted stressed skin
with Fowler flaps airfoil : NACA
Comet Mk.3 G-ANLO at Honolulu airport, 13 December 1955
The Comet 3 , which flew for the first time on 19 July 1954, was a Comet 2 lengthened by 15 ft 5 in (4.70 m) and powered by Avon M502/521 engines developing 10,000 lbf (44 kN). The variant added wing pinion tanks, and offered greater capacity and range. It was ordered by the Ministry of Supply, Air India, BOAC and Panam. The Comet 3 was destined to remain a development series after the 1954 air crashes, since it did not incorporate the fuselage-strengthening modifications of the later series aircraft, and was not able to be fully pressurised. Only two Comet 3s began construction; G-ANLO, the only airworthy Comet 3, was demonstrated at the Farnborough SBAC Show in September 1954. The other Comet 3 airframe was not completed to production standard and was used primarily for ground-based structural and technology testing during development of the similarly sized Comet 4. Another nine Comet 3 airframes were not completed and their construction was abandoned at Hatfield. In BOAC colours, G-ANLO was flown by John Cunningham in a marathon round-the-world promotional tour in December 1955. As a flying testbed, it was later modified with Avon RA29 engines fitted, as well as replacing the original long-span wings with reduced span wings as the Comet 3B and demonstrated in British European Airways (BEA) livery at the Farnborough Airshow in September 1958. Assigned in 1961 to the Blind Landing Experimental Unit (BLEU) at RAE Bedford, the final testbed role played by G–ANLO was in automatic landing system experiments. When retired in 1973, the airframe was used for foam-arrester trials before the fuselage was salvaged at BAE Woodford , to serve as the mock-up for the Nimrod . Range : 4344 [km] with max.payload. MTOW : 68.000 [kg] Cruise speed : 840 km/hr passengers : 58 – 76. Length : 33.99 [m] wing span : 35 [m], height : 8.99 [m] wing area 187.2 [m2] Max.cruise altitude : 14.000 [m]
sweep angle leading edge: 23.0 [°]
engines in the wingroot and landing gear attached to the wings, fuel tanks in the wings and fuselage
construction : all-metal aluminium-alloy stressed-skin construction with pressurized fuselage fuselage shape : 0
calculation : *1* (dimensions)
measured wing chord : 5.60 [m] at 50% wingspan
mean wing chord : 5.62 [m]
calculated average wing chord tapered wing with rounded tips: 5.59 [m]
wing aspect ratio : 6.24 []
seize (span*length*height) : 10710 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 94.0 [kg/hr]
fuel consumption (econ. cruise speed) : 4053.0 [kg/hr] (5196.1 [litre/hr]) at 23 [%] power
distance flown for 1 kg fuel : 0.20 [km/kg] at 10700 [m] height, sfc : 95.0 [kg/KN/h]
estimated total fuel capacity : 40461 [litre] (29658 [kg])
calculation : *3* (weight)
weight engine(s) dry : 5240.0 [kg] = 27.87 [kg/KW]
weight 814.0 litre oil tank : 69.19 [kg]
oil tank filled with 1.2 litre oil : 1.1 [kg]
oil in engine 31.4 litre oil : 28.2 [kg]
fuel in engine 23.1 litre fuel : 16.92 [kg]
weight engine cowling 564.0 [kg]
total weight propulsion system : 5919 [kg](8.1 [%])
***************************************************************
fuselage aluminium frame : 8333 [kg]
typical cabin layout for 56 passengers : average pitch : 91 [cm] ( 2+2 ) seating in 14.0 rows
pax density (normal seating) : 1.19 [m2/pax]
high density seating passengers : 110 at 5 -abreast seating in 21.9 rows, pitch 81 [cm]
weight 2 toilets : 17.4 [kg]
weight 4 hand fire extinguisher : 13 [kg]
weight buffet : 65.7 [kg]
weight 30 windows : 27.0 [kg]
weight 4 emergency exits : 12.0 [kg]
weight 3 life rafts (dinghy) : 70.0 [kg]
weight oxygen masks & oxygen generators : 36.4 [kg]
Comet 4B
weight emergency flare installation : 10 [kg]
weight emergency evacuation slide : 15 [kg]
weight 2 entrance/exit doors : 24.0 [kg]
weight 2 freight doors (belly) : 8.0 [kg]
weight ladies" powder room : 16 [kg]
weight men"s dressing room : 12 [kg]
weight diplomatic mail locker : 2 [kg]
extra main deck space for freight/mail/luggage etc. : 16.82 [m3]
cabin volume (usable), excluding flight deck : 138.82 [m3]
passenger cabin max.width : 2.97 [m] cabin length : 22.41 [m] cabin height : 2.36 [m]
pressure at cruise height 12192.00 [m] : 0.19 [kg/cm2] cabin pressure : 0.77 [kg/cm2]
weight rear pressure bulkhead : 126.2 [kg]
weight air pressurization system : 39.3 [kg]
fuselage covering ( 226.5 [m2] duraluminium 3.06 [mm]) : 1832.0 [kg]
weight floor beams : 117.9 [kg]
weight cabin furbishing : 354.6 [kg]
weight cabin floor : 606.2 [kg]
fuselage (sound proof) isolation : 191.9 [kg]
weight radio transceiver equipment : 7.0 [kg]
weight dual cloud-collision radar : 25.0 [kg]
weight radio direction finding (RDF) equipment : 5.0 [kg]
weight Sperry Integrated Flight System : 11.0 [kg]
weight artificial horizon : 1.1 [kg]
Comet 4 G-APDN crashed in the Spanish Montseny range in July 1970 during a Dan-Air flight.
weight instruments. : 38.0 [kg]
weight APU / engine starter: 23.5 [kg]
weight lighting : 14.0 [kg]
weight electricity generator : 14.0 [kg]
weight controls : 14.5 [kg]
weight seats : 310.0 [kg]
weight 20230 [litre] main central fuel tanks empty : 1132.9 [kg]
weight air conditioning : 84 [kg]
total weight fuselage : 13336 [kg](18.1 [%])
***************************************************************
total weight aluminium ribs (668 ribs) : 2620 [kg]
weight engine mounts : 94 [kg]
weight fuel tanks empty for total 20230 [litre] fuel : 1133 [kg]
weight wing covering (painted aluminium 2.20 [mm]) : 2339 [kg]
total weight aluminium spars (multi-cellular wing structure) : 3156 [kg]
weight wings : 8116 [kg]
weight wing/square meter : 41.20 [kg]
weight rubber de-icing boots : 38.6 [kg]
weight fin & rudder (14.3 [m2]) : 589.6 [kg]
weight stabilizer & elevator (22.2 [m2]): 914.5 [kg]
weight flight control hydraulic servo actuators: 39.3 [kg]
weight fowler flaps (13.3 [m2]) : 280.9 [kg]
total weight wing surfaces & bracing : 11206 [kg] (15.2 [%])
*******************************************************************
wheel pressure : 8082.8 [kg]
weight 8 Dunlop main wheels (1130 [mm] by 174 [mm]) : 1095.7 [kg]
weight 2 Dunlop nose wheels : 137.0 [kg]
weight hydraulic wheel-brakes : 43.4 [kg]
weight pneumatic-hydraulic shock absorbers : 57.9 [kg]
weight wheel hydraulic operated retraction system : 718.0 [kg]
weight undercarriage struts with axle 1502.2 [kg]
total weight landing gear : 3554.2 [kg] (4.8 [%]
*******************************************************************
********************************************************************
calculated empty weight : 34015 [kg](46.3 [%])
weight oil for 7.7 hours flying : 727.2 [kg]
weight catering : 126.4 [kg]
weight water : 101.1 [kg]
weight crew : 486 [kg]
published operational weight empty : 34210 [kg] (46.6 [%])
calculated operational weight empty : 35456 [kg] (48.3 [%])
********************************************************************
weight 56 passengers : 4312 [kg]
weight luggage : 683 [kg]
weight cargo : 4205 [kg]
zero fuel weight (ZFW): 44656 [kg](60.8 [%])
max. landing weight (MLW) : 48709 [kg](66.3 [%])
weight fuel for 3.2 hours flying : 13065 [kg]
operational weight: 57721 [kg](78.6 [%])
fuel reserve : 15759.1 [kg] enough for 3.89 [hours] flying
operational weight fully loaded : 73480 [kg] with fuel tank filled for 97 [%]
published maximum take-off weight : 73480 [kg] (100.0 [%])
Cockpit of a BOAC Comet 4
calculation : * 4 * (engine power)
power loading (Take-off) : 391 [kg/KN]
power loading (operational without useful load) : 307 [kg/kN]
power loading (Take-off) 1 PUF: 521 [kg/KN]
max. total take-off power : 188.0 [KN]
calculation : *5* (loads)
manoeuvre load : 7.1 [g] at 1000 [m]
limit load : 3.0 [g] ultimate load : 4.5 [g] load factor : 1.1 [g]
design flight time : 4.51 [hours]
design cycles : 3160 sorties, design hours : 14260 [hours]
operational wing loading : 3038 [N/m^2]
wing stress (3 g) during operation : 221 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.87 ["]
max. angle of attack (stalling angle, clean) : 12.30 ["]
angle of attack at max. speed : 1.61 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° : 0.15 [ ]
lift coefficient at max. speed : 0.28 [ ]
lift coefficient at max. angle of attack : 1.14 [ ]
max. lift coefficient full flaps : 1.41 [ ]
induced drag coefficient at max.speed : 0.0053 [ ]
drag coefficient at max. speed : 0.0236 [ ]
drag coefficient (zero lift) : 0.0184 [ ]
lift/drag ratio at max. speed : 11.81 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 69427 [kg]): 254 [km/u]
stalling speed at sea-level with full flaps (normal landing weight): 191 [km/u]
landing speed at sea-level (normal landing weight : 48595 [kg]): 219 [km/hr]
max. rate of climb speed : 615 [km/hr] at sea-level
max. endurance speed : 573 [km/u] min. fuel/hr : 3854 [kg/hr] at height : 9449 [m]
max. range speed : 830 [km/u] min. fuel consumption : 5.362 [kg/km] at cruise height : 10973 [m]
Take-off and landing, note the flap settings
cruising speed : 805 [km/hr] at 10700 [m] (power:23 [%])
max. continuous speed* : 840.00 [km/hr] (Mach 0.79 ) at 10700 [m] (power:24.7 [%])
climbing speed at sea-level (loaded) : 2121 [m/min]
climbing speed at 1000 [m] with 1 engine out (PUF / MTOW) : 1637 [m/min]
climbing speed at 1000 [m] with 2 engines out (2xPUF / MTOW) : 1584 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 313.2 [km/u]
high wheel pressure, can only take off from paved runways
take-off distance at sea-level concrete runway : 1442 [m]
take-off distance at sea-level over 15 [m] height : 1514 [m]
landing run : 937 [m]
landing run from 15 [m] : 1712 [m]
lift/drag ratio : 14.18 [ ]
max. theoretical ceiling : 17700 [m] with flying weight :69427 [kg] line 3359
climb to 1000m with max payload : 0.59 [min]
climb to 2000m with max payload : 1.15 [min]
climb to 3000m with max payload : 1.69 [min]
climb to 5000 [m] with max payload : 2.65 [min]
minimum flying speed at 13000 [m] : 611 [km/hr]
theoretical ceiling fully loaded (mtow- 60 min. fuel:69427 [kg] ) : 17700 [m]
calculation *10* (action radius & endurance)
published range : 5190 [km] with 9200 [kg] useful load and 2694 [kg] fuel reserve 88.1 [%] fuel
range : 5725 [km] with 6 crew and 9200.0 [kg] useful load and 97.2 [%] fuel
range max. fuel : 5891 [km] with 56 passengers with each 12.2 [kg] luggage and 3371 [kg] cargo and 100 [%] fuel
range : 5612 [km] with 110 passengers with each 12.2 [kg] luggage and 95.3 [%] fuel
Available Seat Kilometres (ASK) : 329876 [paskm]
max range theoretically with additional fuel tanks total 48749.1 [litre] fuel : 7091 [km]
useful load with range 500km : 35507 [kg]
useful load with range 500km : 56 passengers
production (theor.max load): 28583 [tonkm/hour]
production (useful load): 7406 [tonkm/hour]
production (passengers): 45080 [paskm/hour]
combi aircraft mail/freight/passengers
oil and fuel consumption per tonkm : 0.145 [kg]
fuel cost per paskm : 0.092 [eur]
crew cost per paskm : 0.017 [eur]
time between engine failure : 610 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
writing off per paskm : 0.044 [eur]
insurance per paskm : 0.0010 [eur]
maintenance cost per paskm : 0.408 [eur]
direct operating cost per paskm : 0.561 [eur]
direct operating cost per tonkm (max. load): 0.885 [eur]
direct operating cost per tonkm (normal useful load): 3.416 [eur]
Literature :
praktisch handboek vliegtuigen deel 5 page 143-146
Jane’s commercial transport aircraft page 149
Wat is dit voor een vliegtuig page 76,77
Straalverkeersvliegtuigen page 152
Jane’s all the world aircraft 1964-1965 page 145
Verkehrsflugzeuge page 81
The Flier’s Handbook page 109
Air International aug’99 page 110 (picture)
Air International dec’98 blz.381 (article)
de Havilland DH.106 Comet 3 Archives - This Day in Aviation
Aerospaceweb.org | Aircraft Museum - de Havilland Comet
de Havilland Comet - Wikipedia
* max. continuous speed : max. level speed maintainable for minimal 30 min.
DISCLAIMER Above calculations are based on published data, they must be
regarded as indication not as facts.
Calculated performance and weight may not correspond with actual weights
and performances and are assumptions for which no responsibility can be taken.
Calculations are as accurate as possible, they can be fine-tuned when more data
is available, you are welcome to give suggestions and additional information
so we can improve our program. For copyright on drawings/photographs/
content please mail to below mail address
(c) B van der Zalm 17 June 2022 contact : info.aircraftinvestigation@gmail.com python 3.7.4