Empire flying boat drawings
Cost inside UK for a one
sheet set to 1:72 scale £6.00 Cost
outside UK for a one page set to 1:72
scale £ 8.00
12,000 drawings were needed to construct the first Short Empire flying boat. All the original tracing masters and stress calculations have been destroyed. The fact that every single print has completely disappeared is difficult to believe but seems to be true. Despite searching for more than fifteen years, I have been not been able to find any other authentic GA drawings than S.23.C.29.013 & S.23.C.29.016. part of the Type Record & show the internal layout & calculations for the weight distribution. Prints of these two Drawings were kindly supplied by a reader of this web site.
I have assembled my
own set of General Arrangement drawings to fill in the
check the accuracy of my drawings, I am appealing for the
sight or loan of any authentic Short Bros.' prints with
the drawing number prefixes of S.23, S.30 or S.33.
My General Arrangement drawings show G-ADHL CANOPUS, a S.23 Pegasus engined flying boat, as originally launched with sprung floats and the dipole radio antenna.
As a start to drawing up my GAs, I looked at all the various versions of the small scale diagrams of the Empire flying boats that exist. If these diagrams are blown up to a common scale for comparison inevitable, but surprising, anomalies appear. For the hull, these are most marked in the length of the hull aft of the main step and in the height of the rudder. The most accurate detailed small scale drawing that I have found is the painting by Keith Bloomfield that forms the centre spread to Profile Publications No. 84. The most surprising is the line diagram in Chris Barnes' Putnam publication, Shorts Aircraft since 1900. The hull in this diagram appears to be some 7 feet (2.13 metre) short, 2 feet (610 mm.) too low and 2 feet (610 mm.) too narrow.
Luckily, the Type Record is in the RAF Museum at Hendon together with Drawings S.23.C.29.013 & S.23.C.29.016. TheRecord provides dimensions for some of the details - ailerons, fin and rudder, engine nacelles and details of the mainplane and tail plane spars. It was lucky too, that Major Mayo's copy of the Maintenance Manual for the S. 23s was with his papers when they were given by his daughter to the Science Museum in London. I have a photocopied copy of the Maintenane Manual in the original Short Bros.' screw bound covers.
The outlines of the hull is taken from Drawing S.23C.29.013. The other Diagrams mentioned here are from the Maintenance Manual. The dimensions of the positions of the steps are shown on the diagrams on pages i and ii of the Manual. The under water hull profiles at Frames 15/16 and 20/21 are shown on Drawing S.23.C.300.12 - a tooling drawing. It shows not the aircraft but the shop truck inserted under a hull in the gantry in No. 3 Shop, to enable the hull to be withdrawn when completed. Some versions of the hull plating diagram show four sections - (A) between Frames 8 & 9, (B) between Frames 25 & 26, (C) between Frames 38 & 39 and (D) between 45 & 46 - starting points to develop a full set of lines when enlarged. A set of lines is currently being generated by Ken Fulford and Ray Dixon, the former a Naval Architect with aeroengineering experience and the latter a retired Ship Draughtsman with Production Planning experience, who have volunteered their time & expertise for the project. They are working to, & amending as necessary, to offsets supplied from the author's set of 1:10 drawings. Ray created the grids on which offsets were set which gave the profile, plan and sections of the hull and topside. Ken then drew the lines and faired all the sections to match.
The plan of the mainplanes is drawn round the spars. The dimensions are shown on page i of the Maintenance Manual. This enables the sweep back of the leading edge to be calculated. The position and length of the datum chord is known from the Type Record and so the sweep forward of the trailing edge can be established. Diagram 22 of the Maintenance Manual shows the spars and the Type Record gives the lengths of the members. The dimension for the elliptical tip is in the Type Record and checked with a tracing taken by an apprentice during his days in No 3 Shop, when the flying boats were being built. The plating of the mainplanes is filled in from Diagram 29 of the Manual and details of the ailerons and flaps come from the Type Record. The co-ordinates of the Short Bros. modified Göttingen Gö436 aerofoil are available and, with the thickness to chord ratio of 19.1% on the centreline of the aircraft, 18.78% at the root and 9% at the tip - all from the Type Record - the aerofoil profiles can be calculated and drawn by computer.
The details of the horizontal alignment of the engine backplates came from Alf Cowling's notebook. Alf was one of the Imperial Airways' team of rescuers of CORSAIR, marooned on the Dangu River in Africa & as Flight Engineer on some of the Suda Bay evacuation flights from Crete. A drawing of a Bristol Pegasus engine on an Empire nacelle was discovered in the library of at RNAS Yeovilton . The key dimensions of the engine were taken from the magnificently preserved, and beautifully sectioned, Pegasus engine. As the Industrial Museum in Bristol is being renovated, the engine is now with the owner, Rolls-Royce Heritage, & will be returned to the Museum when the renovation is complete. A mint condition Pegasus is also part of the Science Museum's collection in London. The Rolls-Royce Heritage collection also displays a rather depressed looking, and incomplete, Perseus sleeve-valve engine similar to those used on most of the S 30 flying boats.
The tail plane span is in the Manual and the plan shown on Diagram 39. Details of the elevators, fin and rudder are in the Type Record . The aerofoil profile for both is RAF 30, blown up to 13.75%.
The floats are shown as Diagram 48 of the Maintenance Manual, the patented springing device is in the patent documents in the Patent Office in London and the rigging angles supplied by Alf''s notebook. The float centres are in the Manual and added detail comes from the floats of Sandringham VH- BRC in the Solent Sky museum at Southampton.
Phil Sims and I worked on our respective books for many years, swapping relevant information. He was more interested in the 'human interest' side of the Empire flying boat story and his book Adventurous Empires covers this corner of aviation history brilliantly. I am more interested in the technical aspects of the Empire flying boat saga so Flying Empires concentrates more on the construction and operation of the flying boats. Together, our books cover a significant part of the history of the Empire flying boats.
Flying Empires traces the pedigree of the S.23, S.30 & S.33 Empire flying boats from the early Felixtowe F flying boats, through Short's biplane flying boats of the 1930s, to the first of the Empires as it emerged from the Seaplane Works at Rochester on 1 July 1936. The names of the flying boats are listed. The construction is described in considerable detail. The functions of the crew are outlined and the operation of the flying boats on the water, taking off, in the air and alighting described. Refuelling, flight refuelling and maintenance are covered.
Short Bros. built forty-two, nearly forty-three, Empire flying boats at Rochester, Kent. The forty-third flying boat was nearly three quarters complete before it was scrapped.
The Empire flying boats were designed in 1934 to implement the Empire Air Mail Scheme, carrying unsurcharged letter mail throughout the British Empire and Dominions between the terminals at Southampton, Durban and Sydney - later continuing to Auckland, New Zealand. Some of the payload was available for small numbers of passengers and freight.
The flying boats were operated by Imperial Airways Limited (IAL), QANTAS Empire Airways (QEA) and Tasman Empire Airways Limited (TEAL) and later, British Overseas Airways Corporation (BOAC).
The IAL and QEA Empire flying boats ran the Empire air Mail Scheme & Programme for two years and ten months, ending with the outbreak of World War II in 1939. With Pan American Airways, the IAL flying boats pioneered the Atlantic crossing and one was employed on the Bermuda-New York service. Two flying boats were armed and impressed into the Royal Air Force to become casualties of the Norwegian campaign. Imperial Airways Limited (IAL) changed to British Overseas Airways Corporation (BOAC).
The second chapter of their service history started in 1940 when the Horseshoe Route came into operation. The Horseshoe flying boats pounded the route, an inverted horseshoe on the map, from Durban, through the Middle East and across India, to Sydney and return. Diversions took two of the flying boats to Crete to evacuate British military personnel. The Horseshoe Route was broken at by the capture of Singapore and the QEA flying boats on the Australian side of the break became involved actively involved in the hostilities. Some QEA flying boats were armed as were the two TEAL flying boats that maintained the link between Sydney and Auckland throughout the war, doubling as reconnaissance bombers as required. Two BOAC flying boats were converted to military status for service with the Royal Air Force. The Horseshoe Route lasted for six years and nine months.
Sixteen of the original forty-two survived the war, to be broken up for produce. The very last Empire flying boat remained as a landlocked exhibit in Auckland until it too was hauled off for scrapping some time after 1954, so ending a significant era of aviation history of the 1930s & 40s.
All the 42 Empire flying boats were built in the main assembly shop - No. 3 Erecting Shop - of the Seaplane Works at Rochester in Kent UK, beside the River Medway. Nothing is left of the Seaplane Works now, their former position only marked by the slipway. The first Empire flying boat, S. 23 Construction number S. 795 G-ADHL CANOPUS, went down the slipway outside No.3 Shop in July 1936 and the last, an S.33, S.1026 G-AFRA CLEOPATRA, in May 1940.