Short Empire - version overview:
S.23
A transport and mail flying boat, designed as required by the Department of Aviation for routes between Britain and Australia. Officially named the C Class and all 31 machines built were given names beginning with the letter C. Used by Imperial Airways and Quantas. During World War II, two machines were assigned to the RAF, armed and used as patrols and others taken over as BOAC and RAAF transports.
S.30
Nine machines fitted with Bristol Perseus engines in place of the original Pegasus and greatly increased range and payload. several used for in-flight refuelling experiments. During the war, two were taken over by the RAF and another by the BOAC.
S.33
The last two machines, built in 1939, were given the original Pegasus engines and were essentially no different from the S.23. They were taken over directly by BOAC.
S.21 Maia
A flying boat derived from the S.23 and used as the carrier aircraft of the Mayo Composite system, bringing up the "parasite" transport seaplane S.20 Mercury.
S.26
Three enlarged G Class machines, intended for transatlantic transport by Imperial Airways, but due to the outbreak of war all armed and taken over by the RAF as VIP transports.
Source.
Norris, Geoffrey. The Short Empire Boats, Profile No.84. Profile Publications, Leatherhead 1966.
www.century-of-flight.net
http://en.wikipedia.org/wiki/Short_Empire
S.23
A transport and mail flying boat, designed as required by the Department of Aviation for routes between Britain and Australia. Officially named the C Class and all 31 machines built were given names beginning with the letter C. Used by Imperial Airways and Quantas. During World War II, two machines were assigned to the RAF, armed and used as patrols and others taken over as BOAC and RAAF transports.
S.30
Nine machines fitted with Bristol Perseus engines in place of the original Pegasus and greatly increased range and payload. several used for in-flight refuelling experiments. During the war, two were taken over by the RAF and another by the BOAC.
S.33
The last two machines, built in 1939, were given the original Pegasus engines and were essentially no different from the S.23. They were taken over directly by BOAC.
S.21 Maia
A flying boat derived from the S.23 and used as the carrier aircraft of the Mayo Composite system, bringing up the "parasite" transport seaplane S.20 Mercury.
S.26
Three enlarged G Class machines, intended for transatlantic transport by Imperial Airways, but due to the outbreak of war all armed and taken over by the RAF as VIP transports.
Source.
Norris, Geoffrey. The Short Empire Boats, Profile No.84. Profile Publications, Leatherhead 1966.
www.century-of-flight.net
http://en.wikipedia.org/wiki/Short_Empire