FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1935
1935 - 1432.PDF
642 FLIGHT. JUNE 13, 1935. system, and non-linearity of ccntrol-hinge moments. In vestigations are also in hand on th£_f]«Jt±er of servo-control and servo-balanced systems, and on the flutter of airscrew blades. METALLURGY. DEPARTMENT. ] 'v Magnesium Alloys.—Magnesium alloys are being investigated for the Metallurgy Research Board as part of the programme of research, on light alloys for the Aeronautical Research Committee. The object is to develop lighfalloys stronger than those at present available, for use both at ordinary and elevated temperatures. There is a demand among aircraft constructors for improved magnesium aflbys. Particular atte%tion is being given jfto the discovery of metals which are soluble in solid magnesium, and which are more soluble at elevated than at ordinary temperatures, so that the strength of the alloys can be jn^iproved by -heart-treat ment. This involves the study of microstructure and con stitution, as well as of rolling and mechanical properties. Ti^s design data for such important engineering components as engine crankshafts. vThe fatigue resistance has been determined of three materials, >w5>-^I) 0.1 per cent, carbon steel, (II) 3^ per cent, nicktl- chromram'-steel, and (III) " Silal " cast iron, representing two ductile steelsafcijtjSerejjt types and a " brittle" material. For each material the fatigue resistance has been determined under reversed plane bending and reversed torsional stresses, and under five combinations of these types of stressing actions. The results of the tests show that the fatigue limits of cast iron are in close accordance with^the criterion of 'Maximum Principal Stress; the results obtained on the two steels show that the fatigue rimits of fji£se ductile metals can be expressed by a simple relation of a gerieraT"ft»rm. Stretjfgtii of Thin Sheet-metal Panels.—When thin sheet materitfT is loaded by compressive or shearing forces in the plane of the sheet, the relation between the load and the deformation may be very much affected by the occurrence of buckling. Thus, in the case of a plane rectangular panel of work >s made more difficult because magnesium alloys cannot , sheet material having all its edges supported, and loaded readily oe forged and rolled^ For this/reason it4as beeen neces- . compression parallel to one pair of edgesf buckling will cause sary to evolve methods of hot-working the cast metal. Special ; immediate reduction of the stiffness to one-third of the attention has been given to the cflfefct <A /tow pressing, and it has been found possible to work by this.means alloys which are difficult or impossible to roll satisfactorily. In some cases material which has first been pressed ran then be rolled more easily. Investigation of the mechatticai and working proper ties of magnesium-cadmium-zinc Ins! magnesium-cadmium- ulumiuium alloys has been continued; and an intensive study has been made of an alloy containing"'8 per cent, cadmium and 8 per cent, aluminium. A paper describing results of this work has recently been published by the Institute of Metals. ENGINEERING DEPARTMENT Fatigue Under Combined Stresses.—The new N.P.L. combined-stress fatigue-testing machines have been continu ously employed on a comprehensive investigation of the strength of metals under combined alternating stresses, the main objects of the work being the determination of the stress criterion which produces failure, and the provision of stiffness before buckling, and further increase of loatl will cause a further reduction. Tests on curved panels-carried out at the Laboratory have shown that in this case also buckling causes an immediate reduction of the effective stiffness, and empirical formulas describing the behaviour of the panels before and after buck ling are being devised. PHYSICS DEPARTMENT Silencers for Aircraft Engines.—Detailed studies have been made of the silencers used with internal-combustion engines. Pure notes are introduced at the input, and the emergent sound is observed. It appears that silencers in general sup press the high notes rather than the low, and that certain types become more efficient for silencing low notes when (as in actual use) there is a stream of gas flowing through them. EIGHTY Sound Constructional Features of a Douglas- engined Single-seater Monoplane Built by an Enthusiast AN intriguing little single-seater monoplane, the Tipsy " S," with , a 600 ex. Douglas engine, has been built by Mr. E. O. Tips, who represents the Fairey Company in Belgium. According to Mr Tips the machine flew for about an hour and a half on the first day it was launched and made ings; no modification or adjustment was needed. A low-wing cantilever monoplane was decided upon after several other layouts, such as biplane and braced monoplane had been investigated. The wing is entirely of wood. There is a main spar of I " section, located at the deepest point of the wing section about the first quarter of the chord, and an auxiliary box spar. Between the spars is a rigid diagonal pyramid bracing which maintains the torsional rigidity of the wing. This is further guaranteed by stressed plywood skin over the leading edge. The wing section tapers from R.A.F. 48 near the root to R.A.F. 38 and 28 and becomes thinner at the tips. Ailerons are large and differentially operated. Fabric covering is employed aft of the main spar. The fuselage, which is entirely of wood, embodies four spruce longerons with spruce frames assembled by birch plywood " bis cuits," and is covered witn a birch plywood stressed skin. The pilot's cockpit is located at the centre of gravity. It con tains all the usual equipment of touring machines and a light metal seat shaped to take a parachute. There is ample space for light luggage. The forward part of the fuselage is built integral with the wing. Flush with the trailing edge the rear part is assembled to this forward portion by four easily detachable nickel-steel The Tipsy "S " is an extremely pretty little aeroplane. several land- fittings. The fin is plywood covered and built in one unit with the rear portion of the fuselage. It carries a fabric covered rudder, and is braced to the tail plane by two stream lined tubes. This latter member is fabric covered, has a ply wood leading edge, and is adjustable on the ground. The elevators, likewise, are fabric covered. Rudder and fin are located forward of the tail plane and elevators, so as not to be screened by these members at large angles, or during a recovery from a spin. Two low-pressure air wheels, held in forks attached to the main spar, are embodied in the landing gear, the attachment points of which have rubber bushes. The forks and wheels are covered by elektron fairings. A 600 c.c. Douglas flat-twin engine is fitted and drives a two- bladed wooden airscrew. The engine mounting is of welded and riveted steel tubes, and the fireproof bulkhead, tanks and cowling are of aluminium. The main data on the Tipsy "S" are as follow:— Span, 24ft. Gin. ; length. 18ft. ffin. ; wing area, 100 sq. ft. ; tare weight, 267 !b.: all up weight, 5321b.: maximum speed, 80 rn.p.h. ; cruising speed, 70 m.p.h.: stalling speed, 40'm.p.h. ; take-off run (without wind), 160 yd. : landing run (without wind), :i0 yds. Climb and ceiling figures have not yet been measured, but appear very good 8S compared with those attained by other aircraft of equivalent power.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
