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weight and performance calculations for the Short L.17 Scylla
Short L.17 Scylla
role : multi-engined passenger aircraft
importance : **
first flight : 26 March 1934 operational : July 1934
country : United-Kingdom
design :
production : 2 aircraft
general information :
The fuel is carried in three tanks in the top wing, total capacity 2841 litre, sufficient for ca. 6 hrs flight. Cross feed to all engines by a collector box. Oil tanks in the nacelle behind the engines. Engines started by a Bristol type gas starter, located in a small compartment in the buffet. Landing gear with Dunlop 22 by 26 inch wheels (56 by 66 cm) with high wheel pressure. The long spacious cabin gives a wide distribution of the load which makes a careful trimming necessary. To do this a special luggage compartment is situated between the two lavatories and can be used for trimming the aircraft with different loads. Spacious cabin with room for 39 passengers, 2-3 seating layout. 2 lavatories and a buffet (like a galley/pantry in modern aircraft) from which meals can be served. The forward passenger compartment is for smoking passengers. Canin heating is provided for by muffs fitted around the exhaust pipes, the hot air being led by aluminium ducts to the cabin. Payload with max fuel (2841 litre), oil and 4 crew : 2381 kg so over it’s max range 965 km it can carry only ca. 25 passengers.
The empty weight is somewhat high as a ratio to the MTOW. Reason for this can be found in the wing construction taken from a flying boat matched with a new designed duraluminium fuselage with wheel landing gear and the luxurious passenger cabin interior arrangements. Wing chord : 4.19m. Length of fuselage : 23.57m max. width of fuselage : 3.50m max.passenger cabin width : 3.28m.
Imperial airways used the Scylla and Syrinx for flights from London to Paris and to other European cities. Both aircraft were taken out of service by BOAC in 1940, after Scylla was wrecked in a storm at Drem, Scotland, winter 1940.
users : Imperial Airways
registrations : G-ACJJ “Scylla”, G-ACJK “Syrinx”
crew : 4 passengers : 39
engine : 4 Bristol Jupiter XFBM supercharged air-cooled 9 -cylinder radial engine 555
[hp] (413.9 KW)
dimensions :
wingspan : 34.44 [m], length : 25.55 [m], height : 9.63[m]
wing area : 242.9 [m^2]
weights :
max.take-off weight : 15195 [kg]
empty weight operational : 10274 [kg] useful load : 3500 [kg]
performance :
maximum speed :220 [km/hr] at sea-level
cruise speed :198 [km/u] op 100 [m]
service ceiling : 5000 [m]
range : 945 [km]
description :
2-bay biplane with fixed landing gear and tail strut
two spar upper and lower wing
all-metal (duraluminium) airplane
engines between the wings, fuel in the upper wing, landing gear attached to the
fuselage
airscrew :
four wooden fixed pitch 4 -bladed tractor airscrews with max. efficiency :0.62 [ ]
estimated diameter airscrew 4.25 [m]
power loading prop : 48.69 [KW/m]
The Scylla had a Marconi type A.D.41A/42A medium-wave telegraph-telephone set, located behind the pilots seats.
prop efficiency ratio: 1.31 [1/s]
angle of attack prop : 18.41 [ ]
reduction : 0.50 [ ]
airscrew revs : 1100 [r.p.m.]
pitch at Max speed 3.33 [m]
blade-tip speed at Vmax and max revs. : 252 [m/s]
calculation : *1* (dimensions)
wing chord : 4.19 [m]
mean wing chord : 3.53 [m]
calculated wing chord (rounded tips): 3.89 [m]
wing aspect ratio : 9.77 []
estimated gap : 3.91 [m]
gap/chord : 1.11 [ ]
seize (span*length*height) : 8474 [m^3]
calculation : *2* (fuel consumption)
oil consumption : 41.4 [kg/hr]
fuel consumption(cruise speed) : 384.5 [kg/hr] (524.5 [litre/hr]) at 76 [%] power
distance flown for 1 kg fuel : 0.51 [km/kg] at 2500 [m] height, sfc : 306.4 [kg/kwh]
estimated total fuel capacity : 2841 [litre] (2083 [kg])
calculation : *3* (weight)
weight engine(s) dry : 1852.0 [kg] = 1.12 [kg/KW]
weight reduction gear : 82.8 [kg]
weight 305.4 litre oil tank : 25.96 [kg]
oil tank filled with 12.4 litre oil : 11.1 [kg]
oil in engine 9.2 litre oil : 8.3 [kg]
fuel in engine 11.3 litre fuel : 8.28 [kg]
weight 223.0 litre gravity patrol tank(s) : 33.4 [kg]
weight Bristol type gas starter : 10.1 [kg]
weight cowling 16.6 [kg]
weight airscrew(s) (wood) incl. boss & bolts : 594.0 [kg]
total weight propulsion system : 2699 [kg](17.8 [%])
***************************************************************
fuselage aluminium frame : 1348 [kg]
cabin layout : pitch : 87 [cm] (2+3) seating in 8 rows
weight two toilets : 16 [kg]
weight 4 fire extinguisher : 12 [kg]
weight buffet : 33.9 [kg]
weight racks for hand luggage : 19.5 [kg]
weight 16 windows : 14.40 [kg]
passenger cabin width : 3.36 [m] cabin length : 7.89 [m] cabin height : 1.90 [m]
Syrinx the 2 nd built aircraft
weight cabin furbishing : 190.90 [kg]
weight cabin floor : 169.40 [kg]
bracing : 435.1 [kg]
fuselage covering ( 123.3 [m2] duraluminium 0.75 mm) : 244.4 [kg]
weight radio navigation equipment : 7.0 [kg]
weight instruments. : 4.0 [kg]
weight lighting : 9.8 [kg]
weight controls : 12.2 [kg]
weight seats : 215.0 [kg]
weight air conditioning : 58 [kg]
total weight fuselage : 2782 [kg](18.3 [%])
***************************************************************
weight wing covering (painted aluminium 0.75 mm) : 984 [kg]
total weight ribs (220 ribs) : 542 [kg]
weight engine mounts : 83 [kg]
weight fuel tanks empty for total 2618 [litre] fuel : 209 [kg]
load on front upper spar (clmax) per running metre : 2052.4 [N]
load on rear upper spar (vmax) per running metre : 1232.4 [N]
total weight 8 spars : 685 [kg]
weight wings : 2211 [kg]
weight wing/square meter : 9.10 [kg]
weight 8 interplane struts & cabane : 788.7 [kg]
weight cables (189 [m]) : 306.3 [kg] (= 1620 [gram] per metre)
diameter cable : 16.3 [mm]
weight fin & rudder (13.8 [m2]) : 127.4 [kg]
weight stabilizer & elevator (27.3 [m2]): 250.6 [kg]
total weight wing surfaces & bracing : 3976 [kg] (26.2 [%])
*******************************************************************
wheel pressure : 7597.5 [kg]
weight 2 wheels (1750 [mm] by 350 [mm]) : 496.8 [kg]
weight tailskid : 40.1 [kg]
weight undercarriage with axle 199.9 [kg]
total weight landing gear : 736.8 [kg] (4.8 [%]
*******************************************************************
********************************************************************
calculated empty weight : 10194 [kg](67.1 [%])
weight oil for 5.7 hours flying : 237.0 [kg]
calculated operational weight empty : 10431 [kg] (68.6 [%])
published operational weight empty : 10274 [kg] (67.6 [%])
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"
weight crew : 324 [kg]
weight fuel for 2.0 hours flying : 769 [kg]
weight catering : 65.1 [kg]
weight water : 26.1 [kg]
********************************************************************
operational weight empty: 11615 [kg](76.4 [%])
weight 39 passengers : 3003 [kg]
weight luggage & freight : 497 [kg]
operational weight loaded: 15115 [kg](99.5 [%])
fuel reserve : 79.8 [kg] enough for 0.21 [hours] flying
operational weight fully loaded : 15195 [kg] with fuel tank filled for 41 [%]
published maximum take-off weight : 15195 [kg] (100.0 [%])
calculation : * 4 * (engine power)
power loading (Take-off) : 9.18 [kg/kW]
power loading (operational without useful load) : 7.02 [kg/kW]
power loading (Take-off) 1 PUF: 12.24 [kg/kW]
total power : 1655.5 [kW] at 2200 [r.p.m]
calculation : *5* (loads)
manoeuvre load : 3.1 [g] at 1000 [m]
limit load : 2.5 [g] ultimate load : 3.8 [g] load factor : 1.2 [g]
design flight time : 3.34 [hours]
design cycles : 3120 sorties, design hours : 10423 [hours]
operational wing loading : 469 [N/m^2]
wing stress (3 g) during operation : 155 [N/kg] at 3g emergency manoeuvre
calculation : *6* (angles of attack)
angle of attack zero lift : -1.34 ["]
max. angle of attack (stalling angle) : 11.26 ["]
angle of attack at max. speed : 0.97 ["]
calculation : *7* (lift & drag ratios
lift coefficient at angle of attack 0° :0.12 [ ]
lift coefficient at max. angle of attack : 1.13 [ ]
lift coefficient at max. speed : 0.21 [ ]
induced drag coefficient at max. speed : 0.0025 [ ]
drag coefficient at max. speed : 0.0307 [ ]
drag coefficient (zero lift) : 0.0282 [ ]
calculation : *8* (speeds
stalling speed at sea-level (OW loaded : 14811 [kg]): 106 [km/u]
landing speed at sea-level: 124 [km/hr]
min. drag speed (max endurance) : 152 [km/hr] at 2500 [m](power :48 [%])
10 October 1935 G-ACJK “Syrinx” was blown over by strong winds while taxiing for take-off at Brussel airport. It ended upside down seriously damaged, but there were no casualties. The aircraft was rebuilt but now fitted with Pegasus XC engines.
min. power speed (max range) : 152 [km/hr] at 2500 [m] (power:48 [%])
max. rate of climb speed : 132.0 [km/hr] at sea-level
cruising speed : 198 [km/hr] op 2500 [m] (power:71 [%])
design speed prop : 209 [km/hr]
maximum speed : 220 [km/hr] op 100 [m] (power:105 [%])
climbing speed at sea-level : 289 [m/min]
calculation : *9* (regarding various performances)
take-off speed : 128.7 [km/u]
static prop wash : 167 [km/u]
take-off distance at sea-level : 156 [m]
lift/drag ratio : 12.38 [ ]
climb to 1000m with max payload : 5.48 [min]
climb to 2000m with max payload : 11.87 [min]
climb to 3000m with max payload : 20.02 [min]
practical ceiling (operational weight 11615 [kg] ) : 6718 [m]
practical ceiling fully loaded (mtow- 30 min.fuel:15003 [kg] ) : 5183 [m]
calculation *10* (action radius & endurance)
published range : 945 [km] with 4 crew and 2604.9 [kg] useful load and 88.1 [%] fuel
range : 484 [km] with 4 crew and 3500.0 [kg] useful load and 45.1 [%] fuel
range : 539 [km] with 39.0 passengers with each 10 [kg] luggage and 50.3 [%] fuel
Available Seat Kilometers (ASK) : 21027 [paskm]
max range theoretically with additional fuel tanks total 6388.7 [litre] fuel : 2412 [km]
useful load with range 500km : 3712 [kg]
useful load with range 500km : 37 passengers
production (useful load): 734.98 [tonkm/hour]
production (passengers): 7722.00 [paskm/hour]
none of very little cargo capability
oil and fuel consumption per tonkm : 0.58 [kg]
oil and fuel consumption per paskm : 0.06 [kg]
fuel cost per paskm : 0.06 [eur]
crew cost per paskm : 0.04 [eur]
writing off per paskm : 0.11 [eur]
insurance per paskm : 0.06 [eur]
rigging cost per paskm : 0.00 [eur]
maintenance cost per paskm : 0.48 [eur]
direct operating cost per paskm : 0.75 [eur]
direct operating cost per tonkm : 7.47 [eur]
Literature :
Wikipedia
Piston engined airliners page 20,21
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/
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(c) B van der Zalm 10 May 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4