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On the application of boundary layer control to a slender wing supersonic airliner cruising at M = 2.2
No full textThe use of suction or injection to reduce the drag of a supersonic airliner is
considered. It is shown that injection gives no reduction in operating costs.
With suction applied to an M =2.2 aircraft on the London - New York route, the
basic operating cost of 13.30d per short ton statute mile is expected to be
reduced by 0.5d for the same payload assuming no change in configuration.
If the theoretical maximum skin friction reduction could be obtained the payload
could be increased by 4750 lb. and the direct operating cost could be reduced to
10.63d per short ton statute mile
Experimental investigation on a cropped delta wing with edge blowing
No full textLow speed wind tunnel tests have been made on a 70° cropped delta wing with edge
blowing both in the plane of the wing and at a downward deflection angle of 30°.
The tests include six-component force and moment measurements, the distribution
of static pressure at four chordwise stations, and quantitative measurements of
the flow in the leading edge vortex.
At a constant incidence, blowing increases the size and strength of the
leading edge vortices and moves the vortex cores outwards and upwards. Blowing
also tends to suppress the secondary separation due to the entrainment effect
of the jet. Blowing from the streamwise tips and trailing edge was relatively
ineffective and most of the tests were made with blowing from the swept leading
edges only, with tips and trailing edge sealed
Boundary layers with suction and injection a review of published work on skin friction
No full textAvailable data on the effects of suction and injection on skin
friction are summarised and compared.
It is shown that injection into a turbulent boundary layer can
produce a skin friction coefficient lower than the laminar value at trio
same Reynolds number on an impermeable plate
High frequency vibration analysis of plate structures
No full textNoise and vibration are important design issues for many types of
vehicles such as ships, cars, and aeroplanes. Structure borne sound,
which may be of relatively high frequency, usually emanates from an
engine or some other type of localised source and propagates through the
vehicle. Excessive vibration levels, and thus structural damage, may
occur while structural acoustic interactions may lead to unacceptable
interior noise.
In the analysis of energy transmission between plate structures, it is
common practice to consider only bending modes (or waves) of the
structure. However if the concern is with high frequency vibration
analysis, then due allowance may need to be made for the presence of inplane
shear and longitudinal modes.
Due to the infeasibility of the industry standard technique, the Finite
Element Method, at high frequencies, almost all of the studies that have
investigated the importance of in-plane energy transmission have used
Statistical Energy Analysis (SEA).
In this study an existing dynamic stiffness method is extended to include
in-plane effects, and used as a benchmark against which SEA is assessed.
Additionally the Wave Intensity Analysis (WIA) technique, which is an
improved form of SEA, is extended to in-plane vibrations, and used to
identify some of the reasons for the poor performance of SEA in certain
applications. All three methods are applied to a wide range of plate
structures within the frequency range of 600 Hz to 20 kHz. While the
response levels as predicted by the WIA are generally quite close to
exact results, it has been found that although all of the requirements
which are usually postulated for the successful application of SEA are
fulfilled, SEA severely underpredicts the energy transmission in large
structures because of the diffuse wave field assumption. It is also shown
that the exclusion of in-plane modes may lead to sizeable errors in
energy predictions unless the structure is very simple
Design Synthesis for Swept-Wing Combat Aircraft Incorporating Stealth Technology
No full textThe College of Aeronautics has been involved in several research contracts funded by the Defence Research Agency of the United Kingdom to investigate the design synthesis and optimization of Military aircraft. This report presents the results of the latest such investigation into the enhancement of a swept-wing combat aircraft design synthesis to incorporate stealth technology.
In the light of the current changes in the method of procurement of airborne weapons systems it has become necessary to develop combat aircraft which are effective against a wide range of threats whilst meeting the requirements of both navy and air force. One way of doing this is to incorporate into combat aircraft those features which make it stealthy, in other words reducing their detectability by means of radar, infrared, visual and acoustics identification methods. Although the full benefits of stealthy aircraft may only become apparent when such systems are deployed within appropriate strategic and tactical environment, it is important to define the features inherent to the aircraft at the conceptual design stage.
This report briefly describes those features of stealthy aircraft incorporated into the design synthesis, leading to the definition of a baseline aircraft, followed by a full description of the design synthesis methodology. Finally, the development of the design synthesis computer code is outlined, rounded off by plans for future work
A preliminary study of survival rates in civil aircraft accidents, 1966 - 1973, with particular reference to fire risk and fuel type
No full textTo establish whether theoretical and laboratory safety advantages
of low volatily fuel, such as that of low rate of flame spread,
are reflected in aircraft accident 'statistics' a preliminary
study has been made of the ARB's world airline accident summary.
An advantage has been found in that the change to kerosine has
apparently halved the death rate in survivable accidents.
In all gas turbine accidents, including those where death was
probably due to impact not fire, the death rate seems to be 50%
higher with wide cut gasoline than with kerosine.
It has also been found that a higher proportion of gasoline
powered aircraft accidents involved impact death 1.1-1d that overall
the survival rate has remained virtually unchanged. A critical
examination of these preliminary findings, in the light of the
relevant accident reports, is planned
Stress redistribution due to creep in nimonic 90 ministry of aviation contract no. PD/28/021 report for the period January 1964 - June 1965: part 1
No full textThe period covered by this report has been devoted to the design,
construction development and calibration of a special apparatus to simulate
the stress redistribution conditions occurring during the creep of a cooled
turbine blade. The experimental assembly consists of two creep machines,
each operating at a different temperature, so controlled that a load is
shared between them. maintaining equal creep strains (and in consequence
equal creep rates) in each specimen. The stress in each specimen and the
creep strain of the pair are automatically measured and recorded by a
specially developed unit. Some preliminary results on an aluminium alloy
are presented
Swift aquaplaning trials
No full textThe object of the investigations at Cranfield is to
investigate the effect of water depth, surface roughness —
drainage characteristics and tyre pressure on aquaplaning and
tyre ground friction.
Tests at Cranfield are full scale on the single main—
wheel undercarriage of a Vickers Supermarine Swift F.7. operated
through ponds of water on a test surface. The test area is a
precision surface, level to an accuracy of 1/16" over its entire
width. The levelled area is built into runway 22-04 and consists
of six different surfaces of varying texture, three of concrete
and three of asphalt arranged as shown in fig. 1. The ponds
are constructed of 1 1/2" T section rubber strip affixed to the
surfaces by suitable adhesives which were selected after a series
of tests.
The Swift is fitted with an A.22 recorder giving
traces of port and starboard wheel speeds, obtained by means of
wheel speed generators, and airspeed. A modification is in hand
to record oleo leg extension as a measure of wheel load and
hydrodynamic force
An abstract of a paper by D. Battat 'a new kinetic approach to the shock wave structure'
No full textPilot reliability investigation: final report on agreement PD/28/035/ADM
No full textThe feasibility of constructing a device to give a measure
of pilot reliability has been investigated. A rig to meet the proposals
made by BLEU has been designed and basic circuits constructed and tested
for accuracy of operation and reliability. An estimate of the materials
required and the cost of construction has been made.
The rig has been designed to be subject operated for twentyfour
tests before requiring attention, and devices have been incorporated
to indicate unserviceability and prevent operation if starting cond4 tions
are not correct.
Switching sequences typical of the final period of an autoland
approach are demanded verbally by magnetic tape replay equipment and the
performance of the subject measured. The test consists of two phases;
a preparatory or "unloaded" phase, and a "loaded" phase during which
the subject performs a tracking task in addition to the switching
sequence. The performance of the subject is recorded on veeder counters
for both phases of the test in the form of actions demanded, actions
taken and actions taken during a memory period. A measure of performance
of the tracking task is also given by veeder counter