The Robinson “Redwing”
Attractive New Light ‘Plane with Side-by-Side Seating.
CERTAIN amount of criticism has been levelled at aircraft manufacturers during the last year or so for carrying out a policy which has been described as the over-development of the light aeroplane. Critics have stated that by the continual increase in horse-power, and the additions in weight and elaborations, makers have placed the private-owner’s machine right outside the class for which it was originally intended, and left uncatered for, a large number of potential purchasers.
This cannot be said of The Robinson Aircraft Co., for in their recently-introduced ” Redwing” one finds a machine in which simplicity, medium engine-power and low running and maintenance costs are the most salient features. The ” Redwing ” has, in fact, been produced specifically for the man who is not so much concerned with high maximum and cruising speeds and “salooncar comfort” as he is with cheapness in first cost, small running expenses and general handiness.
The” Redwing” has been designed by Mr. John Kenworthy, to the ideas of Mr. P. G. Robinson, who until recently was with Imperial Airways. Mr. Kenworthy, it may be recalled, was responsible for the little singleseater ” Whippet ” which was built as long ago as 1919 by the Austin Motor Co. Unfortunately at the time the ” Whippet ” was made there was little or no market for the small owner-pilot’s aeroplane ; otherwise with its advanced design (which included folding wings and metal construction) it would probably have proved very popular. In general the ” Redwing “follows orthodox practice, being a wooden wire-braced biplane ; it is somewhat unusual in one respect however, in having side-by-side seating. This has been adopted in the belief that the demand for a better degree of sociability is one that can no longer be ignored, and anyone who has tried it will agree that it makes flying ” two-up ” a much more pleasant business, as conversation can be carried on without the use of speaking tubes. It also does away
with the necessity of duplicated instruments. By careful planning, moreover, the disadvantages, which are sometimes attached to the side-by-side .arrangement, of excessive frontal area and blind-spots have been surmounted in the Robinson machine. As may be seen from the Photographs, the pilot, whether he flies from the starboard or port side, has a view ahead which is entirely unobstructed by any portion of the cowling or engine, and although the cockpit is placed beneath the centre-section the visibility above and around, compares quite favourably with that of most machines.
The fuselage is of the three-ply box girder type, with square section spruce longerons and intermediate struts and bracings of the same material. The whole is built up to form a very rigid unit in which it is impossible for twist and distortion to occur. Large doors are provided in the underside to allow for inspection and maintenance of the interior when required, which incidentally, should be very seldom. The whole is finished off with three coats of varnish and enamel, and behind fie cockpit a spacious locker is provided, underneath the decking. This is fitted up with two suitcases, as part of the machine’s standard equipment.
The wings are built up in the usual way, with spruce spars, compression and form ribs, and piano-wire internal bracing. The spars are of the box type, having spruce flanges and three-ply webs. Ailerons are fitted to the bottom planes only, and like the rudder and elevator are of composite build of metal and wood. The wings and controlling surfaces are fabric covered. The tail is attached to the top longerons by simple metal plates, and has a fixed angle of ,incidence. It is braced below by two streamlined steel tubes, and above by Rafwires to the peak of the fin. The rudder is partially balanced. The main planes are made to fold back ; the lower ones are attached at their root to two dural tubes, which are fitted across the bottom longerons. They pivot on the rear spars, and the whole is a very neat, simple arrangement which allows the folding to be carried out in about a minute. jury struts are employed when the wings are hinged back.
The interplane and centre section struts are not of wood, but of high tensile steel tube, streamline in form. The wing bracing is by Rafwire throughout.
The undercarriage of the” Redwing “is of very sound construction, and incorporates the Oleo type of shock absorber, in which all valves and springs are eliminated. The main landing loads are taken partly by oil and partly by rubber buffers. The Oleo legs are double-acting so that when they are forced upwards the oil acts as a damper and prevents them from extending again too rapidly. The result is a marked absence of bounce in landing. As can be seen in the illustrations the Oleo legs are attached at their uppermost extremities to the top longerons, adjacent to the diagonal struts of the centre section. There is, of course, no axle, and this together with the wide ‘track allows the pilot to put the ‘plane down on very rough ground without any undue risk of turning over. The tail-skid is a welded-steel member and operates against an enclosed spring. It has a quickly-detachable shoe.
Like other manufacturers, the Robinson concern offer alternative power units for .their machine. Their first machine has an 85 h.p. A.B.C. ” Hornet ” installed. This engine is a double-opposed four-cylinder, very similar in many respects to the well-known A.B.C. “
Scorpion” fiat-twin. By reason of its construction the ” Hornet ” contributes considerably to the clear front view from the cockpit, and as the cylinder-heads project through the cowling the valve gear and sparkling plugs are exceedingly accessible. The motor is fitted with a special ” Watford ” magneto which supplies two simultaneous sparks to each cylinder, and an impulse starter and a” Ki-gass “priming device ensures quick starting. A wooden propeller is attached direct to the crankshaft. The engine is fitted on a steel bedplate, which incorporates a rubber shock-absorbing device, in order to
minimise the transmission of vibration to the fuselage and the rest of the craft. The petrol and oil tanks are placed in the fuselage, just in front of the cockpit. The feed to the engine is by gravity, and all leads are of ” Superflexit ” flexible tubing.
The cockpit is comfortable, deep, and free from draughts. And by slightly staggering the seats, the pilot and passenger are given plenty of elbow room. The instrument board is well laid out, so that each instrument—the rev, counter, air speed, altimeter, pressure guage, clock and cross level—are easily read from either seat. It is worth mentioning that the lead to the oil gauge, which is a frequent cause of forced landings owing to its fracturing, is encased in a stout rubber tubing to eliminate this possibility. The control installation consists of the usual stick and rudder bar. The latter is made adjustable over a wide range to accommodate pilots of different heights. Wherever possible pull and push rods are used and cables are only used in straight lengths ; there are, therefore, no pulleys or fairleads, which in time cause fraying, and as all the moving parts in the system have large bearing surfaces (which are lubricated by ” Tecalemit “) wear is practically eliminated. The span of the ” Redwing ” is 30ft. Gins., and as the fully-loaded weight is only 1,325 lbs., her lifting surface area and light wing loading give her a very good take-off. The performance figures stated by the makers are as follows :—
Top speed, 92 m.p.h. ; cruising speed, 84 m.p.h.; climb, 1,000 feet in 11 minutes.
The landing speed is remarkably low, being 30 m.p.h., at which speed it can also be flown with the engine throttled down, under complete control. This controlability at low speeds is attributed to the wing section, which was calculated by the designer specially for the machine. The ” Redwing ” carries a Certificate of Airvvorthi
ness in the full aerobatic category, and although it is obviously not a fierce super-performance craft, it can, when required, be used for stunting. Incidentally, the ” Redwing ” has the distinction of being the only light ‘plane to go through all the numerous tests for C. of A. in a single day, which is surely an excellent indication of its soundness of design and good qualities in general. At the present time it has only just emerged from the experimental stage, but having done so, it is now being put into regular production, and the Robinson concern are laying out their works at Waddon, Surrey, to turn out an initial quantity of three machines a week. The following is further data of the ” Redwing ” :—
Span 30 feet 6 inches ; span, with wings folded, 9 feet 8 inches ; length 22 feet, 3 inches ; height, 8 feet 4 inches ; weight empty, 805 lbs. ; weight loaded, 1,325 lbs. ; tank capacity, 15 gallons. Standard equipment : two safety belts, “Float-on-Air upholstery, full engine tool kit, Tecalemit grease gun, picketing rings, ” Kigass ” primer, floor mat, ladies’ companion, aircraft .and engine log books. The price of the standard machine is 2575, and if required it can also be had with such extras as Handley Pages slots,, compass, dual control and waterproof covers for the engine, propeller and cockpit.