Flight, August 1930

THE "HENDY" 302
A Low-Wing Cabin Monoplane with Cirrus-Hermes Engine

   FROM whatever point of view one regards it, the "Hendy" 302 monoplane, produced for the King's Cup Air Race, is a machine of more than usual interest. Aerodynamically, it is characterised by high efficiency, both in the matter of minimum drag and high L/D and high Kl max. Structurally, it is simple, robust and rigid, at the cost, perhaps, of a slightly increased structure weight. And as a practical aeroplane for the private owner it is comfortable, roomy and well-behaved. In fact, put quite briefly, there is very little in the "Hendy" 302 that one could reasonably wish to have altered.
   Before giving a description of the actual machine, a few notes dealing with the people who produced it may be of assistance to those of our readers to whom the Henderson Aircraft Company is something of an unknown quantity. Mr. Basil B. Henderson was, for several years, on the Avro technical staff at Hamble. When that firm decided to close down the Hamble works, Mr. Henderson resigned his position and formed, with Mr. H. A. Miles (who is not to be confused with Mr. F. G. Miles of the Southern Aircraft Co.), the Henderson Aircraft Co. A small shed was obtained at the Shoreham aerodrome, and in this, Henderson and Miles set to work. Mr. Henderson had for some time been pondering an idea for a new type of wing spar construction, and now was the opportunity to test out the idea on an actual machine. Funds were not too plentiful, and something unambitious was indicated. Mr. Henderson chose the type of machine which could be built at the smallest cost, while yet definitely proving the soundness or otherwise of Mr. Henderson's idea for a new spar. That machine was the little "Hobo," a single-seater low-wing monoplane with A. B.C. "Scorpion" engine. After many vicissitudes, the machine was completed and flown, and not only did it prove quite successful as a single-seater machine, but it showed that the new type of wing spar did in practice what Mr. Henderson had calculated that it should do. The spar was very rigid, and not only gave very little deflection under bending loads but, what was more important still, proved, as had been hoped, that the Henderson form of construction gave a wing very strong in torsion.
   The "Hobo" was built in 1929. Mr. Henderson's programme included testing out the new spar on larger machines, either in wood or, if possible, in metal, the principle of the spar design lending itself very well to all-metal construction. In the meantime, Capt. E. W. Percival was interested in machines suitable for private owners, and was keen on getting a machine to fly in the King's Cup Air Race. The next step in Mr. Henderson's programme was a two-seater development of the little "Hobo," and the general "scheme" appealed to Capt. Percival. The upshot was that he decided to join forces with Henderson and Miles, they to do the actual design work, calculations, etc., and Percival to contribute practical advice out of his long and varied experience of aircraft at home and in Australia A contract was entered into with George Parnall of Bristol for the construction of the machine, and work was begun at once, as was very necessary in view of the fact that there was but four months in which to design and build the machine and test it out in readiness for the King's Cup Race.
   In the experience of every aircraft designer it happens now and then that a certain prototype is absolutely "right" from the very start, and when that happens the final result is always very much better than in the case of a new type which has to have this, that and the other altered before it is absolutely "right." The "Hendy" 302, as the new two-seater was called, proved one of these instances. When it came to be tested it did all that was expected of it in the way of performance - or a little better. It appeared to have no vices, and its controls were effective over the whole speed range. In the King's Cup race, as we have previously pointed out, compass trouble prevented a good course being flown, and the machine was not "placed." Had the same average speed been maintained as that made good from London to Manchester, the "Hendy" 302 would have secured 2nd place. That was not to be, but those who watched closely the performance of the various machines realised that in the "Hendy" 302 one had a new type with an obviously good performance. It could not have beaten Miss Brown, and so on its handicap could not have won the race. But had it secured second place this would have been an excellent advertisement for the machine. There is no reason to doubt, however, that when the "Hendy" 302 is placed on the market it will find a ready sale, its performance and general qualities being sufficient to sell it, even without the advertisement of winning the race.
   The "Hendy" 302 is a two-seater, low-wing cantilever monoplane, with the occupants protected by a hinged cabin top. It is difficult to believe that in these modern times anyone could object to a cabin, but should any potential purchaser of this machine do so, it would be a very simple matter to unship the hinged top and use the machine as an ordinary open touring aeroplane.
   Structurally, the "Hendy" 302 is almost entirely of wood construction, the exception being the undercarriage legs, the engine mounting, and a very few metal fittings. Three-ply wood enters largely into the construction, the fuselage being planked with this material, which also serves many purposes in the wing structure.
   The cabin is very roomy, and the seats are remarkably comfortable. Contrary to expectations, the view from both seats is very good. For some peculiar reason the chord of the wing seems to "shrink" as soon as the machine has reached a height of a hundred feet or so, and it is then possible from the rear seat to look over the leading edge while the rear seat is far enough back to enable one to look straight down. From the pilot's seat (the front one) the view is also very good in practically all directions, the narrow top of the engine cowling, and the generous window panel area, giving a degree of view which one would scarcely expect from an external examination of the machine.
   A novel form of wing construction was, as already pointed out, the main reason for the construction of the little "Hobo," and this has been retained in the "302." The two main spars are T-section beams built up of a single central web of three-ply, with rectangular-section strips on each side forming the flanges, as shown in a sketch. The drag bracing, composed of wooden strips arranged in the form of a lattice, is in top and bottom planes of the spar flanges, and attached to them by three-ply gussets or "biscuits." The construction is very simple and has proved exceptionally strong in torsion. Moreover, it could readily be "translated" into metal construction, and we trust Mr. Henderson will have an opportunity to test his spar design on a metal wing. The wing section is a "calculated" one, in which the centre of pressure is not entirely stationary, but its movement has been kept down to a very small amount. We do not know what is the minimum drag coefficient of the section, nor the maximum lift coefficient, but the speed range of the machine indicates that the section is a good one, and on climb, taking into account slipstream effect, etc., the L/D of the whole machine is about 8-3, which is remarkably good.
   The wide-track undercarriage is of the "split" type, and the telescopic legs have spiral springs and oleo gear for absorbing shock and damping bouncing. On the first machine plain wheels are used, but we gather that the production type will have wheel brakes.
   A steel tube mounting supports the engine en porte a faux, forked plates securing the mounting to the fuselage corners. The engine cowling is slightly unusual, and has scoops in the top, from which short lengths of tube project down to the cylinder heads, directing the draught on to the hottest parts of the cylinder heads. Normally, the oil temperature does not exceed 50 deg., and even in the King's Cup Race, with the engine running "full out" the temperature never exceeded 70 deg. So that it looks as if the cooling is beyond reproach.
   Petrol is carried in the wings. At present there is a tank of 16 gallons capacity in the port wing, and a gravity tank of 9 gallons in the fuselage. If desired, another 16-gallon tank can be put into the starboard wing, thus increasing the total capacity to 41 gallons, or a range of about 750 miles.
   We had the pleasure recently of making a flight with Capt. Percival in the "Hendy" 302, and found the cabin very comfortable indeed, although the short exhaust pipes used in the King's Cup Race were still in place, which naturally made the noise greater than it will be in the production machine. The view, as already mentioned, was a great deal better than one would expect and is, in fact, well above the average. The machine handled nicely, and the performance was obviously good, both in take-off (although the racing prop. was still on), climb and speed. The speed range is as a matter of fact, unusually great, the maximum being about 132 m.p.h., and the minimum well below the 40 m.p.h. without the machine showing any tendency to fall into a spin. Cruising at 1,900 r.p.m., the speed is 112 m.p.h., and even throttled to 1,800 r.p.m., the speed is still over 100 m.p.h. At 1,900 r.p.m., the fuel consumption is about 6 gallons per hour, giving a mileage of about 19 miles per gallon (at 112 m.p.h.).
   We gather that arrangements are now being made for the quantity production of the "Hendy" 302. In the meantime, anyone interested is advised to write to the Hendy Aircraft Co., at Shoreham Aerodrome, Sussex.

Flight, July 1934

NEW AEROPLANES IN KING'S CUP RACE

HENDY "HECK" AND "HOBO"

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   The "Hobo" was one of Mr. Henderson's earliest efforts, and when originally designed was fitted with the A.B.C. "Scorpion" engine of only 35 h.p. For the race a new Certificate of Airworthiness has been granted, allowing the use of a Pobjoy "Cascade" engine, and in this guise the performance should be quite out of the ordinary. The machine is particularly robustly constructed, with a three-ply covered fuselage, and has a very wide undercarriage. Although only a single-seater, its performance should be sufficiently high to give it a wide appeal amongst sporting pilots who like to have an open machine solely for the pleasure of flying. Constructionally, a definite family likeness can be traced from this machine via the "Hendy 302" (which, incidentally, was first produced as an open two-seater machine, and only had a cabin top fitted after it was acquired by its present owner, Mr. C. S. Napier, Technical Director of the Cirrus-Hermes Engineering Co.) down to the Hendy "Heck."
   Mr. Henderson has consistently got just a little more out of his machines than has generally been expected, so both the "Heck" and the "Hobo" may be counted upon as possible "dark horses" for the race. The "Heck" has been built under the direction of Mr. Henderson in the Westland Aircraft Works at Yeovil.