High-Speed Photography Applied to High-Speed Aerodynamic Research at the National Physical Laboratory

1960 ◽  
Vol 69 (10) ◽  
pp. 711-719 ◽  
Author(s):  
R. J. North
Keyword(s):  
High Speed ◽  
National Physical Laboratory ◽  
High Speed Photography ◽  
Physical Laboratory

scholarly journals High-frequency fatigue tests

1925 ◽  
Vol 109 (749) ◽  
pp. 119-143 ◽  
Keyword(s):  
Mild Steel ◽  
High Frequency ◽  
High Speed ◽  
Fatigue Testing ◽  
National Physical Laboratory ◽  
Fatigue Tests ◽  
Research Committee ◽  
Engineering Research ◽  
Physical Laboratory ◽  
The Cost

The experiments on high-frequency fatigue in copper, Armco iron, and mild steel described in the following paper were carried out in the Engineering Laboratory, Oxford, for the Fatigue Panel of the Aeronautical Research Committee. The cost of the apparatus was defrayed by a grant from the Engineering Research Board of the Department of Scientific and Industrial Research. In 1911 Prof. B. Hopkinson called attention to the importance of ascertaining whether the fatigue limit of metals was dependent on the rate of alternation of stress. He designed and made an electric alternating directstress machine, and published the results of tests on mild steel carried out at about 7,000 periods per minute (116 per second), which was more than three times as fast as any tests made up to that time. The results at this speed were compared with those made by Dr. Stanton at the National Physical Laboratory on the same material at 2,000 periods per minute (33 per second). Prof. Hopkinson considered that the results showed that speed had a marked effect, but he did not consider that his tests were conclusive. In the light of the knowledge gained on fatigue testing since that date neither set of tests can be considered satisfactory. The question is of importance to the users of high-speed machinery. It is also of importance when comparisons are made between tests carried out at different speeds, and, finally, it has a bearing on the causes of fatigue failure. For these reasons it appeared to be desirable to make a more thorough investigation, and, if possible, to extend the tests to very much higher speeds.

The Thermal Rating of Worm Gearboxes

1944 ◽  
Vol 151 (1) ◽  
pp. 326-337 ◽  
Author(s):  
Harry Walker
Keyword(s):  
Temperature Rise ◽  
High Speed ◽  
Testing Machine ◽  
National Physical Laboratory ◽  
Worm Gear ◽  
Variable Load ◽  
Power Losses ◽  
Heating And Cooling ◽  
Physical Laboratory ◽  
Worm Gears

The paper deals with the factors affecting the temperature rise of totally enclosed self-lubricated gearboxes, with particular reference to worm gearboxes, and is based on observations obtained from a power circulating apparatus through worm gears which has provision for the accurate measurement of efficiency and temperature rise under variable load and speed. The theory underlying the heating and cooling of gearboxes is discussed, for gears running under continuous load and also under a repeated cycle of intermittent load. Temperature rise depends on the heat-dissipating capacity of the gearbox and the power losses within the box; heat-dissipating capacity is dealt with in relation to surface area of the box, speed of the gears, and artificial cooling by air fan; power losses are discussed under the headings of efficiency and oil drag losses. It is shown that gear speed and turbulence in the lubricant contribute considerably to heat-dissipating capacity, and that oil drag losses play an important part, particularly on large gears running at moderate or high speed. Cooling by air or other means is shown to result in an increase in power capacity (for a given allowable temperature rise) much more than in proportion to the increase in heat-dissipating capacity of the box, owing to a higher overall efficiency when transmitting heavier loads. Results of worm gear efficiency tests carried out in the past on the Daimler-Lanchester testing machine at the National Physical Laboratory on the author's design of worm gear, which gave the highest efficiency of any published tests carried out on this machine, are reconsidered in the light of recent work and it is contended that the National Physical Laboratory machine gives efficiency figures which are in general higher than the true efficiency.

scholarly journals High-Speed Vessels and the Collision Regulations

1972 ◽  
Vol 25 (2) ◽  
pp. 263-266
Author(s):  
G. H. Draysey
Keyword(s):  
High Speed ◽  
National Physical Laboratory ◽  
Traffic Density ◽  
Special Regard ◽  
Testing Ground ◽  
Physical Laboratory ◽  
High Traffic Density ◽  
Early Alteration

It has become increasingly apparent that there is a pressing need to amend the Collision Regulations with special regard for the requirements of high-speed vessels. My experience as a Commander of a hydrofoil on a scheduled passenger service, in an area of high traffic density, has led me to write this paper and to add weight to the argument in favour of an early alteration of the existing Rules.There are more and more types of vessel today capable of speeds in excess of 40 and indeed up to 60 or more knots. In the Solent area alone, there are two hovercraft services and a hydrofoil service. In addition there are the experimental craft of the National Physical Laboratory, the Inter-Service Hovercraft Unit and several manufacturers use the area as a testing ground for their vessels. There are all types of high-speed vehicles proceeding in all directions, at speeds which 10 years ago would have been considered impossible.

The Conversion of the Stanton 3-Inch High-Speed Wind Tunnel to the Open Jet Type

1937 ◽  
Vol 135 (1) ◽  
pp. 445-466 ◽  
Author(s):  
A. Bailey ◽  
S. A. Wood
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Characteristic Curve ◽  
National Physical Laboratory ◽  
Chamber Pressure ◽  
Observation Chamber ◽  
Physical Laboratory ◽  
Engineering Department ◽  
Curve Method ◽  
Set Up

The 3-inch high-speed wind tunnel developed by Stanton has been converted in the Engineering Department of the National Physical Laboratory to the open jet principle, the working jet now being contained in a square glass-sided chamber. The pressure in the observation chamber can be controlled within certain limits by altering the axial length of the gap between the inlet and outlet, and the presence of standing waves in the jet can be largely eliminated by bringing the chamber pressure to a value equal to that in the jet at the chamber inlet. In place of the divergent jet used by Stanton, an approximately parallel working jet has been obtained in the modified tunnel by using inlet nozzles with profiles determined by a graphical construction based on the “characteristic curve” method given by Busemann. An optical system has also been fitted enabling Schlieren photographs of the flow pattern to be obtained. Measurements of the wave systems set up round model cones indicate agreement with the theory established by Taylor and Maccoll which they found to accord with the results of larger-scale firing trials on conical-headed shell, thus providing evidence of the close similarity between conditions in the tunnel and on the full scale.

The Conversaziones in 1938

1938 ◽  
Vol 1 (2) ◽  
pp. 67-69
Keyword(s):  
High Speed ◽  
National Physical Laboratory ◽  
Control Device ◽  
Aerial Photographs ◽  
Voltage Stabilizer ◽  
Cavendish Laboratory ◽  
Industrial Firms ◽  
Ordnance Survey ◽  
Physical Laboratory ◽  
Electric Impulse

The usual Conversaziones were held on 18 May and 22 June; on both occasions by the courtesy of the President and Council of the Geological Society their first floor library was opened and was used for the service of refreshments. Of those invited to the first one, 624 availed themselves of the opportunity to see the exhibits which were arranged on the ground floor and the first floor. The Cavendish Laboratory showed a liquid helium fountain in operation; and a new form of Quartz Oscillator for use as a standard of frequency and time was exhibited by the National Physical Laboratory. The Research Department, Woolwich, contributed a thyratron counter chronograph which has been designed to measure the velocity of projectiles; while from the Ordnance Survey and the Cambridge Instrument Co. came a stereo-comparator for making accurate measurements of co/ordinates on a pair of aerial photographs. The research laboratories of several industrial firms contributed various types of instruments of high accuracy which were of interest to many. Messrs Ilford Ltd. sent a voltage stabilizer, and a filming device for providing an electric impulse for a definite predetermined period. The Brown-Firth Co. Ltd. showed a voltage control device to maintain steady temperature with electrically/heated ‘creep’ specimens. The British Thomson-Houston Co. Ltd. demonstrated their high speed recurrent surge oscilograph, as well as a miner’s pneumatic lighting unit using a mercury discharge lamp.

A Wide-Band Computing Amplifier and A High-Speed Analogue Multiplier

SIMULATION ◽  
1964 ◽  
Vol 3 (1) ◽  
pp. 55-58
Author(s):  
Derek L.A. Barber
Keyword(s):  
Operational Amplifier ◽  
High Speed ◽  
Wide Band ◽  
National Physical Laboratory ◽  
Physical Laboratory

The design of an operational amplifier is discussed and theoretical values of stage gains for maximum bandwidth are deduced. A practical circuit is de scribed in which these theoretically desirable stage gains are achieved. The result is an amplifier with a bandwidth about two orders greater than is commonly attained, which, furthermore, is the best performance that may reasonably be realized with the valves that are employed. The amplifier, together with a high-speed multi plier, forms the basis of the Fast Analogue Com puting Equipment (FACE) developed at the National Physical Laboratory.

The Drag Effects of Roughness at High Sub-Critical Speeds

1950 ◽  
Vol 54 (476) ◽  
pp. 534-540 ◽  
Author(s):  
A. D. Young
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
High Speed ◽  
National Physical Laboratory ◽  
Appreciable Effect ◽  
Drag Effect ◽  
Physical Laboratory ◽  
Mach Numbers ◽  
Constant Mach Number ◽  
Made In

Measurements were made in the Royal Aircraft Establishment High Speed Tunnel of the drag of a wing with various grades of surface roughness in the form of camouflage paint. The measurements were made for a range, of Reynolds number from about 4.5 × 106 to about 15 × 106 at a constant Mach number of 0.2, and for a range of Mach numbers from 0.2 to about 0.7 at a constant Reynolds number of 4.5 × 106 and to about 0.6 at a constant Reynolds number of 6.0 × 106. It was found that for the range of Mach numbers tested compressibility had no appreciable effect on the drag increase due to roughness (Figs. 2 and 3). Further, the drag effect of each roughness tested was such that an equivalent size of sand roughness Ke, of the type tested by Nikuradse, could be readily associated with it. For each finish tested a number of roughness records were taken by means of a roughness gauge developed by Dr. Tomlinson, of the National Physical Laboratory (Fig. 5).

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