Bristol 188

https://en.wikipedia.org/wiki/Bristol_188

The Bristol 188 is a British supersonic research aircraft built by the Bristol
Aeroplane Company in the 1950s. Its length, slender cross-section and intended
purpose led to its being nicknamed the "Flaming Pencil".

The aircraft had its genesis in Operational Requirement 330 for a high speed
(Mach 3) reconnaissance aircraft , which eventually developed into the Avro 730.
As the 730 was expected to operate at high speeds for extended periods of time,
more data was needed on high speed operations, leading to Operational
Requirement ER.134T for a testbed capable of speeds greater than Mach 2. The
aircraft was expected to run at these speeds for extended periods of time,
allowing it to study kinetic heating effects on such an aircraft. The aircraft
was expected to spend a considerable amount of time with a skin temperature
around 300 Celsius.

Several firms took interest in this very advanced specification and the eventual
contract (6/Acft/10144) was awarded to Bristol Aircraft in February 1953.

The advanced nature of the aircraft meant that new construction methods had to
be developed. Several materials were considered for construction and two
specialist grades of steel were selected: a titanium-stabilized 18-8 austenitic
steel and a 12%-Cr steel used in gas turbines (Firth-Vickers Rex 448). These had
to be manufactured to better tolerances in sufficient quantities for
construction to start. The 12% chromium stainless steel with a honeycomb centre
was used for the construction of the outer skin, to which no paint was applied.
Riveting was a potential method for construction but the new arc welding
technique using an Argon gas shield known as puddle welding was used. There were
long delays with the method, which was less than satisfactory. The W. G.
Armstrong Whitworth company provided substantial technical help and support to
Bristol during this period; they produced major sections of the airframe as a
subcontractor.

A fused-quartz windscreen and canopy and cockpit refrigeration system were
designed and fitted but were never tested in the environment for which they had
been designed.

The specification for the aircraft required engine installations which permitted
the fitting of different air intakes, engines and propelling nozzles. The 188
was originally intended to have Avon engines but the Gyron Junior was
substituted in June 1957.

The Gyron Junior was then under development for the Saunders-Roe SR.177
supersonic interceptor and incorporated a fully variable reheat, from idle to
full power, the first such application used in an aircraft. Unfortunately this
choice of powerplant resulted in the 188 having a typical endurance of only 25
minutes, not long enough for the high-speed research tests that were required.
Chief Test Pilot Godfrey L. Auty reported that while the 188 transitioned
smoothly from subsonic to supersonic flight, the Gyron Junior engines were prone
to surging beyond that speed, causing the aircraft to pitch and yaw.

In order to solve the aerodynamic and flutter problems, a large number of scale
models were tested. Some, mounted on converted rocket boosters, were launched
from RAE Aberporth, for free-flight investigation.


Role
Experimental aircraft

Manufacturer
Bristol Aeroplane Company

First flight
14 April 1962

Retired
1964

Status
Experimental

Primary user
Royal Aircraft Establishment

Number built
3 (one static test, two flight test prototypes)

The first prototype made its first public appearance in September 1962 when it
was displayed on the ground and in the air at that year's Farnborough Air Show.
In the same year the aircraft was seen in the film Some People.

Measurements collected during testing were recorded onboard and transmitted to
the ground station for recording. The flight information transmitted meant that
a "ground pilot" could advise the pilot.

The project suffered a number of problems, the main being that the fuel
consumption of the engines did not allow the aircraft to fly at high speeds long
enough to evaluate the "thermal soaking" of the airframe, which was one of the
main research areas it was built to investigate. Combined with fuel leaks, the
inability to reach its design speed of Mach 2 and a takeoff speed at nearly 300
mph (480 km/h), the test phase was severely compromised. Nonetheless, although
the 188 programme was eventually abandoned, the knowledge and technical
information gained was put to some use for the future Concorde program. The
inconclusive nature of the research into the use of stainless steel led to
Concordes being constructed from conventional aluminium alloys with a Mach limit
of 2.2. Experience gained with the Gyron Junior engine, which was the first
British gas turbine designed for sustained supersonic operation, additionally
later assisted with the development of the Bristol (later Rolls Royce) Olympus
593 powerplant which was used on both Concorde and the BAC TSR-2.

Various proposals to further develop the 188 were considered including
incorporating ramjets and rocket engines as well as considering fighter and
reconnaissance variants. One serious proposal involved the fitting of "wedge"
type intakes.

The announcement that all development was terminated was made in 1964, the last
flight of XF926 taking place on 12 January 1964. In total the project cost £20
million. By the end of the programme, considered the most expensive to date for
a research aircraft in Great Britain, each aircraft had to be "cannibalised" in
order to keep the designated airframe ready for flight.

Specifications (Bristol 188)

General characteristics
Crew: 1
Length: 77 ft 8 in (23.67 m)
Wingspan: 35 ft 1 in (10.69 m)
Height: 12 ft (3.65 m)
Airfoil: biconvex section, 4 per cent t/c ratio
Powerplant: 2 × De Haviland Gyron Junior DGJ10Rs turbojet with reheat Dry
thrust: 10000lbf each (44 kN) each
Thrust with afterburner: with reheat 14000lbf at sea level, 20000lbf at 36000ft
(62 kN at sea level, 88 kN at 36000ft) each

Performance ?

The Bristol 188 (XF923) was prominently featured in "Some People" (1962), a
feature film primarily shot in Bristol



*

On Wed, 12 Dec 2018 07:19:18 -0800, Miloch wrote:

https://en.wikipedia.org/wiki/Bristol_188


This airframe looks amazingly similar to the Lockheed SR-71
Blackbird and its construction, using titanium alloys, is also
similar.

Since both the SR-71 and the 188 were conceived in the 1950's,
could these similarities be more than a coincidence?

The honeycombed stainless steel skin is also reminiscent of the XB-70.