Boulton Paul Balliol

Infobox Aircraft
name=Balliol
type=Two-seat Trainer
manufacturer=Boulton Paul Aircraft


caption=Sea Balliol
designer= John Dudley North
first flight= 30 May 1947
introduced=1950
retired=
status=Retired
primary user=Royal Air Force
more users=Royal Navy Fleet Air Arm
Royal Ceylon Air Force
produced=
number built=229
unit cost=
variants with their own articles=The Boulton Paul Balliol and the related Sea Balliol were monoplane military advanced trainer aircraft built for the United Kingdom's Royal Air Force (RAF) and the Royal Navy Fleet Air Arm (FAA) by Boulton Paul Aircraft. The Balliol was designed to replace the North American Harvard trainer and used the Rolls-Royce Merlin engine, with the Sea Balliol a naval version with folding wings and arrestor hook for training in deck landing.

Design and development

The Balliol was developed to meet Air Ministry specification T.7/45 for a three-seat advanced trainer powered by a turboprop engine, competing against the Avro Athena. The first prototype first flew on 30 May 1947, being temporarily powered by an 820 hp Bristol Mercury 30 radial engine. The second prototype, powered by the intended Armstrong Siddeley Mamba turboprop, first flew on 17 May 1948, the world's first single-engined turboprop aircraft to fly. The Air Ministry had second thoughts about its training requirements, and issued a new specification, T.14/47, requiring a two seat trainer, powered by a Rolls-Royce Merlin piston engine.

The Merlin powered Balliol, designated Balliol T.2, first flew on 10 July 1948, and after extensive evaluation, it was chosen over the Athena, with large orders being placed to replace Harvards in RAF service.Donald 1997]

By 1951, however, the Air Ministry changed its mind about its training requirements yet again, and decided to introduce a jet-powered advanced trainer.

Operational history

Pre-production Balliols were delivered to the RAF's Central Flying School in 1950, but with the change in air-training policy, the Balliol was only delivered to one Flying Training School, - No. 7 at RAF Cottesmore, later serving at the RAF College, Cranwell. The Balliol served with the RAF until replaced by the de Havilland Vampire T.Mk.11 in 1956.

The Balliol saw limited squadron service with 288 Squadron from 1953 based at RAF Middle Wallop. Operations continued until the squadron was disbanded in September 1957. [ Jefford, "RAF Squadrons"]

Production

* P.108 Balliol T.Mk 1 : Prototypes. 3 built. Powered by Armstrong Siddeley Mamba

* Balliol T.Mk 2 : Two-seat advanced training aircraft for the RAF; 196 built, (166 built by Boulton Paul, and 30 built by Blackburn Aircraft).

* Sea Balliol T.Mk 21 : Two-seat advanced training aircraft for FAA. A total of 30 built by Boulton Paul.

Operators

;UK

* Royal Air Force
**No. 288 Squadron RAF
**No. 238 O.C.U.
**No. 7 Flying Training School
**Central Flying School
**RAF College Cranwell

* Royal Navy, Fleet Air Arm

;SRI
*Royal Ceylon Air Force

pecifications (T.2)

aircraft specifications
plane or copter?=plane
jet or prop?=prop
ref=Aircraft of the Royal Air ForceThetford 1957]
crew=2
capacity=
length main= 35 ft 1½ in
length alt= 10.71 m
span main= 39 ft 4 in
span alt= 11.99 m
height main= 12 ft 6 in
height alt= 3.81 m
area main= 250 ft²
area alt= 24.2 m²
airfoil=
empty weight main= 6,730 lb
empty weight alt= 3,059 kg
loaded weight main= 8,410 lb
loaded weight alt= 3823 kg
useful load main=
useful load alt=
max takeoff weight main=
max takeoff weight alt=
more general=

engine (prop)= Rolls-Royce Merlin 35
type of prop= V-12 piston
number of props= 1
power main= 1,245 hp
power alt= 929 kW
power original=
max speed main= 250 kn
max speed alt= 288 mph, 464 km/h
max speed more= at 9,000 ft
cruise speed main=
cruise speed alt=
never exceed speed main=
never exceed speed alt=
stall speed main=
stall speed alt=
range main= 574 NM
range alt= 660 mi, 1063 km
ceiling main= 32,500 ft
ceiling alt= 9,909 m
climb rate main= 1,790 ft/min
climb rate alt= 9.1 m/s
loading main= 33.6 lb/ft²
loading alt= 158 kg/m²
thrust/weight=
power/mass main= 0.148 hp/lb
power/mass alt= 0.243 kW/kg
more performance=
*Endurance 3 hours at 220 mph
*Climb to 10,000 ft 6 minutes
armament=
* One 0.303 in Browning machine gun
* Provision for four 60-lb rockets.
avionics=

ee also

aircontent

related=

similar aircraft=Avro Athena

lists=List of aircraft of the Royal Air Force

References

Notes

Bibliography

* Donald, David, ed. "The Encyclopedia of World Aircraft". London: Aerospace Publishing, 1997. ISBN 1-85605-375-X.
* Thetford, Owen. "Aircraft of the Royal Air Force 1918-57". London: Putnam, First Edition 1957.
* Thetford, Owen. "British Naval Aircraft since 1912, Fourth Edition". London: Putnam, 1994. ISBN 0-85177-861-5.
* Jefford, C.G., "RAF Squadrons". Shrewsbury: Airlife Publishing, 2nd edition, 2001. ISBN 1-84037-141-2

External links

* [http://www.britishaircraft.co.uk/aircraftpage.php?ID=342 Balliol at British Aircraft Directory]
* [http://www.rafmuseum.org.uk/boulton-paul-sea-balliol-t-21.htm Sea Balliol entry at RAF Museum]