Avro 730

The Avro 730 was a planned British Mach 3 reconnaissance aircraft and bomber for the Royal Air Force. It was cancelled in 1957 along with other development on manned aircraft as part of the 1957 Defence White Paper.

History

During the early Cold War, the RAF bomber fleet of V-bombers was given the nuclear deterrent role. For strategic reconnaissance both pre- and post-bombing, an operational requirement, OR.330, for an aircraft was identified and a specification was drawn up in 1954 for an aircraft that could enter the Soviet Union while avoiding their air defenses. The aircraft envisaged would have to be capable of maintaining Mach 2.5 at 60,000 feet, with the ability to reach Mach 3, and operate at a maximum range of 5,000 nautical miles.

There were submissions from the major UK aircraft manufacturers: the Handley Page HP.100, Vickers SP4, English Electric P.10, Avro Type 730 and a Short Brothers entry. All were futuristic delta or needle shapes in appearance employing several engines, twelve on the HP.100, sixteen mounted horizontally at the rear of the Vickers. The English Electric design used ramjets.

Avro were given a contract in 1955 to develop their submission aircraft as the Type 730. As an aid to development the Bristol Type 188 research aircraft was built to test the wing shape and later effects of prolonged supersonic flight on metal. The first prototype was planned to fly in 1959. The first prototype was being built when the minister, Duncan Sandys, announced the decision to cancel its development. The Bristol 188 project continued though.

Design

The initial Avro 730 was based around a long and thin fuselage with a high fineness ratio, a requirement for sustained high-speed flight. A small tapered almost-rectangular wing was mounted just rear of the midpoint of the fuselage. Four Armstrong-Siddeley P.156 engines were carried, two each mounted over-under in pods at the extreme tips of the wings. No conventional canopy was fitted in order to maintain the fineness ratio, instead the cockpit featured only two small windows facing to the side, and used a retractable periscope for forward viewing during take-off and landing. A crew of three would be carried, pilot, navigator and radar operator.

This initial version was intended strictly for the reconnaissance role, using its "Red Drover" sideways-looking radar to find targets for attack by the V-bomber force that would follow. As development progressed it became clear that the radar would not need as big an antenna as initially believed, freeing up considerable internal room. In response, the RAF started concentrating on the secondary bombing role carrying both the radar and also including a long bomb bay for either a weapon or additional fuel. A high-speed bomber requirement was also being studied at the time, OR.336, so the two projects were combined into the new RB.156 requirement. This led to a fairly major redesign.

Although the new version looked much like the original, it was larger overall and featured a new wing planform. In order to increase wing area extra "winglettes" were added outside of the engine pods and the entire planform was re-shaped to be more of a classic delta wing. The wing inside the engine pods, about 2/3rds of the overall span, was swept at about 45 degrees, the smaller area outside was more highly swept at about 60 degrees. The forward sweep on the trailing edge was removed. The engine pods were now specified to carry four Armstrong-Siddeley P.176 engines each, for a total of eight. The pods were circular at the front and mounted a single large shock cone, and grew progressively more "square" to the rear, where they ended flush with the rear of the wing. The rest of the layout was generally the same as the earlier version, with the rectangular canards, "hidden" cockpit and large cropped-delta vertical fin at the extreme rear.

The new version also allowed for a reduction in crew to two, although the reasons for this are not clear considering it still carried the same equipment, and potentially more. The bomb bay was narrow but very long at 50 ft, and was intended to be armed with a nuclear-tipped stand-off missile. A suitable warhead started development as Blue Rosette.

pecifications (Reconnaissance version)

aircraft specifications
plane or copter?=plane
jet or prop?=jet
ref=
crew=
capacity=
payload main=
payload alt=
length main= 163 ft 6 in
length alt= 49.8 m
span main= 59 ft 9 in
span alt= 18.2 m
height main=
height alt=
area main= 2,000 ft²
area alt= 185.8 m²
airfoil=
empty weight main=
empty weight alt=
loaded weight main= up to 200,000 lbs
loaded weight alt= 90,720 kg
useful load main=
useful load alt=
max takeoff weight main=
max takeoff weight alt=
more general=
engine (jet)=Armstrong Siddeley P.176
type of jet=turbojets
number of jets=8
thrust main= 9700lb (43.15 K/N)
thrust alt=
thrust original=
afterburning thrust main=
afterburning thrust alt=
max speed main=
max speed alt= 3850km/h (2220mph) Mach 3
cruise speed main=
cruise speed alt= 2980km/h (1850mph) Mach 2.5
stall speed main=
stall speed alt=
never exceed speed main=
never exceed speed alt=
range main= 5000 nautical miles
range alt=
ceiling main=
ceiling alt=
climb rate main=
climb rate alt=
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=
armament=
avionics=

ee also

aircontent

related=
* Bristol 188

similar aircraft=
* Handley Page HP.100
see also=
*Operational Requirement F.155 - the planned opposition to the expected Soviet high flying supersonic attackers
*List of Air Ministry Specifications
*Rainbow Codes

References

* [http://www.skomer.u-net.com/projects/or330.htm OR.330 - Son of Vulcan]
* [http://www.vectorsite.net/avvulcan_2.html#m5 The Avro 691 & Avro 730] at Greg Goebel's Air Vectors

External links

* [http://www.fantastic-plastic.com/Avro730Page.htm Avro 730 Bomber (1956)]
* [http://www.fas.org/nuke/guide/uk/bomber/avro-730.htm FAS.org]
* [http://www.bisbos.com/rocketscience/aircraft/virtraf/avro730.html Virtual RAF]