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Aviation History
1947
1947 - 0064.PDF
FLIGHT JANUARY I6TH, 1947 LIGHTWEIGHT CANARD disadvantages in the high-speed range and increasedproduction costs. The small wings used on the M.O.-i turther simplify the storage and handling problems. Toed-in end-plate fins "at the wing extremities are usedto give directional stability. Pitching moments are pro- duced by movable elevators attached to the noseplane,this surface combination operating at a higher lift coeffi- cient than the wing and having a much lower aspect ratio.Both of these factors create longitudinal stability. The low aspect ratio front surface has a flat lift-curve slope, and thequarter-chord line of the noseplane /elevator combination is swept forward 10 deg. Forward sweep produces a flat-peaked lift curve which is desirable in reducing the tendency of a Canard type to oscillate following stalling ofthe front surface. The weight balance and lifting forces aredistributed in such a manner that stalling of ' the main wing is impossible. With the pilot'scontrol in the full nose-up position, the lift co-efficient of the front surface will increase toits maximum and be restrained from further increase in angle of attack by a strong nose-down moment producedby the increasing lift coefficient of the wing. It is ex- pected that this system of a low-aspect ratio swept-forwardnoseplane combined with a high-aspect ratio wing will produce a non-stalling, non-oscillating aircraft. A full-span pressure slot is provided in the front surface as a means for producing the high lift coefficients required forbalancing the nose-down moment caused by operation of the flaps. On the subject of drag Mr. Raynes observed that to beof general utility, a personal aircraft must be able in sone measure to compete with airline travel as regards speed.Present-day light aircraft cruising at no to 140 m.p.h. are much too slow for cross-country travel; cruising speedsof 200 to 300 m.p.h. would be much more desirable. Few compromises were made in the M.O.-i design with drag.Considerable investigation was made in the basic fuse- lage contours in an effort to reduce the drag of this com-ponent to a minimum, and a number of approaches to this subject were explored. The method of obtaining sufficient air for submergedengine cooling and flight control purposes was one of the major design problems. External scoops are, of course, out separation, and the consequent drag reduction can becaptured. A pressure-slot is also provided around the tail of the fuselage a short distance ahead of the propeller toaccelerate the boundary layer and so stabilize the flow conditions into the propeller blades. This pressure-slotalso functions as an aid to the re-establishment of the in*, ... creasing pressure gradient, and minimizes the adverse "effect which a pusher propeller has on fuselage drag. Pushers are noted for their poor efficiency caused by thepresence of the fuselage in the up-stream flow. It is ex- pected that the use of both suction and pressure slots inthe after portion of the fuselage will so stabilize the flow',: '! around the fuselage as to produce conditions compatiblewith normal airscrew efficiency. A laminar-$ow wing section is used having excep- Diagrammatic section through sealed wingshowing flow of pressure air to slot in order to effect lateral control. The lower drawingshows the bellows operation of the split flap. the simplest means of obtaining a large quantity of airat suitable pressures; however, a scoop takes in air which is virtually stationary in space and the energy requiredto accelerate this air to the speed of flight absorbs con- siderable power. In the M.O.-i a multitude of slots arearranged around the after portion of the fuselage, and the boundary layer is drawn in through these slots. Two advantages are claimed for this system : first, theair which is taken in has travelled a considerable distance along the fuselage skin and has been accelerated by sur-face friction to a speed near that of flight, so that it is, so to speak, already "on board" and requires no addi-tional energy to accelerate it to the speed of flight. Secondly, by drawing-oil the boundary layer around thecomplete fuselage a lower fineness ratio may be used with- Diagrammatic section of fuselage showing location of nose-plane, cabin, wings, engine and blower, and illustrating the airflow into the blower and out to the surfaces and propeller. tionally low drag coefficients in the range of Reynolds'numbers corresponding to the high-speed condition. The low overall structure weight of the M.O.-i has beenmade possible by a unique grouping of the major forces and weights into a small area. The major weight items,such as the main landing gear, seats, and engine, are all attached to a single bulkhead. The main forces appliedcome from the front spar and main landing gear, thus structural economy and efficiency is achieved. The fuselage bulkheads are used to separate the high-and low-pressure air chambers and to conduct air to the wing and noseplane. No engine mounting in the usualsense is required, since the engine is carried from the cylin- der heads on corner brackets joining the fuselage skin andmain bulkhead. In cases where specialized functions are to be performedand unusual conditions are to be met, designers frequently develop separate devices for each requirement, and theaircraft suffers from added complexities. It is indeed for- tunate when a single device which solves many problemscan be found. Mr. Raynes then mentioned that the blower as used in the M.O.-i furnishes cooling air for theengine, high lift coefficients for the wing, creates condi- tions favourable to a two-control design, makes possibleincreasing lateral control with decreasing speed, operates the flaps, controls airflow conditions ahead of the propeller,compensates for the nose-down moment of the flaps, and eliminates the ailerons. Without in any way wishing to decry the seeming far-sightedness of this design, we cannot but reflect #that it hasthe appearance of having one's cake and eating it too ; nevertheless, we shall await"the flight trial reports withgreat interest. FORTHCOMING EVENTS Jan. 17th.— I.Mech.E. ; " Recent Developments in Flying Boats." Mr. H. Knowler. Jan. 24th.—R.Ae.S. (Belfast Branch) ; Smoking Concert. Jan. 24th.—Aircraft Golfing Society ; First Annual dance. Brent Bridge Hotel, Hendon, N.W.4. Jan 24th.—R.Ae.S. Grad. and Stud. Sectn. ; "The Aerodynamics of High Speed Flight." A. D. Young. Jan. 25th.—Soc. of Licensed Aircraft Engineers ; " Radar inWar and Peace." A.V.-M. D C. T. Bennett. Jan. 25th.—R.Ae.S. (Portsmouth Branch) ; General Discussion on the Prospects of Civil Air Transport by Sir Frederick Handley Page, Sir Harold Hartley and A.V-M. D. C. T. Bennett. Jan. 28th.—R.Ae.S. (Bristol Branch) ; " Large Aircraft." Mr. A E. Russell. Jan. 29th.—R.Ae.S. (Southampton Branch) ; " Installation of Radio Equipment in Aircraft." Mr. W. T. Davies.
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