Service, with separate series for the RFC and Navy. RAF specifications (1918–1920) Data from: The British Aircraft Specifications File 1920–1929 Data from: The British Aircraft Specifications File 1930–1939 {| class="wikitable" |- ! width=100 |Spec ! width=100 |OR ! width=400 |Type ! Designs |- |M.1/30 | |Torpedo bomber – Spec. supersedes M5/28 (q.v.) |Blackburn M.1/30, Handley Page H.P.46, Vickers Type 207 |- |2/30 | |Dual control conversion set issued to Blackburn but then cancelled | |- |3/30 | |Basic trainer – Avro 504N replacement |Avro Type 621 Trainer |- |5/30 | |Mail carrier |Vickers Type 166 Vellore II |- |6/30 | |ab initio trainer – Lynx-Avro (Avro 504N) production order |Avro 504N |- |F.7/30 |OR.1 |Fighter capable of at least 250 mph and armed with four machine guns |Blackburn F.3, Bristol Type 123, Bristol Type 133, Gloster Gladiator, Gloster SS.19, Hawker P.V.3, Supermarine Type 224, Westland F.7/30 |- |8/30 | |ab initio trainer – Moth with Gypsy II order |de Havilland Moth |- |S.9/30 | |Two-seat carrier-borne torpedo bomber/three-seat spotter-reconnaissance aircraft |Fairey T.S.R.I, Gloster FS.36; see also S.15/33 |- |16/30 | |Naval fighter – written for Nimrod |Hawker Nimrod |- |18/30 | |Fairey IIIF replacement |Fairey Gordon I |- |19/30 | |Naval fighter/reconnaissance with folding wings and interchangeable wheel/float U/C |Hawker Osprey |- |G.4/31 |OR.2 |General-purpose/torpedo bomber – Wapiti & Gordon replacement – Wellesley one of two designs submitted by Vickers and itself a PV – see also G.22/35 |Blackburn B-7, Bristol Type 120, Fairey G.4/31, Handley Page H.P.47, Hawker P.V.4, Parnall G.4/31, Vickers G.4/31, Vickers Wellesley, Westland PV-7 |- |5/31 | |Long-range bomber – Virginia production order |Vickers Virginia |- |13/31 | |ab initio trainer with complete freedom for parachute escape by both occupants – D.H.60T accepted with modifications, becoming D.H.82 – see also T.23/31 (some sources give 13/31 as an order for the Ripon IIC) |Avro Type 631 Cadet, de Havilland D.H. 60T Tiger Moth |- |18/31 | |Basic trainer – Avro Type 621 Trainer with Lynx engine |Avro Tutor |- |R.19/31 | |Three-engined long-range reconnaissance flying boat – Rangoon three-aircraft production order |Short Rangoon |- |R.20/31 | |Twin-engined flying boat – all-metal Kestrel-engined Southampton II (Southampton IV/Scapa) |Supermarine Scapa |- |T.23/31 | |Tiger Moth I production order |de Havilland Tiger Moth I |- |R.24/31 |OR.3 |"General Purpose Open Sea Patrol Flying Boat" |Saunders Roe London, Short R.24/31 Knuckleduster, Supermarine Stranraer |- |C.26/31 |OR.4 |Bomber-transport – Valentia replacement |Armstrong