Flight, February 1929

THE MAUBOUSSIN P.M.4
A French Single-Seater Light Monoplane with A.B.C. "Scorpion" Engine

   THE "Motor Cycle of the Air" has not yet materialised in this country, although FLIGHT has good cause to know that the type is keenly awaited by ДальшеMore>>> a large number of enthusiasts who, having learnt to fly, are not able to afford the present day type of two-seater, but who would welcome a cheaper machine, even if this should mean flying solo. We are aware that several machines of the single-seater low-power type are coming along, but so far none is available. Without wishing to suggest that we should copy foreign designers, we think it is of interest to note what other countries are doing, and consequently we are publishing this week general arrangement drawings, photographs and descriptive notes dealing with a machine produced in France, and fitted with a British engine, the A.B.C. "Scorpion."
   The "P.M. 4" monoplane, which forms the subject of these notes, was designed by M. Pierre Mauboussin and built by M. Louis Peyret, whose tandem monoplane glider won the Daily Mail glider competition at Itford some years ago, piloted by M. Maneyrol. Actually, the P.M. 4 was designed partly for last year's international light 'plane competition at Orly, and partly to test certain theories of the designer's, who has in contemplation a larger machine of which this may be regarded in some way as a large flying model. The P.M. 4 was not, however, finished in time to take part in the Orly meeting, but it has now been completed and is undergoing tests by the French Section Technique.
   The P.M.4 is a high-wing monoplane, with the pilot enclosed in a small cabin provided with windscreen and side windows. To British eyes the most unusual feature of the design is the extremely short fuselage. The distance from the trailing edge of the wing to the leading edge of the tail plane is less than one chord length (i.e., of maximum chord), and one would expect such a short machine to be rather "tricky" on the controls. The wing section employed is seen to have a reverse curvature, and the travel of the centre of pressure may therefore be assumed to be restricted, if the c.p. is not actually stationary. For counteracting yawing the short lever arm of the rudder would appear to be a disadvantage, although possibly the relatively large rudder area and high "aspect ratio" of the rudder help to make up for any shortcomings in length of lever arm.
   For the rest, the P.M.4 is comparatively orthodox, but characterised by wings of trapezoidal plan form, of large span. The ailerons extend over the whole span (with the exception of the extreme wing tip), and are divided into two portions, of which the outer portion acts as an aileron while the inner portion is used as a camber-varying device.
   The monoplane wing, which is in one piece, is of all-wood construction, and has two main spars carrying wooden ribs, the whole being covered with three-ply wood. The wing is attached to the fuselage by four tapering bolts, and as it is a pure cantilever, there are no other attachments. The wing form is rather pretty, and probably very efficient, but would appear to be somewhat expensive to build.
   The fuselage is of square cross-section, with a light internal framework and ply-wood covering. Windows in the sides give light and view, while the windscreen in front of the pilot, sloping up to the leading edge of the wing, gives a good view forward, the more so as the extreme nose is dropped and the flat-twin arrangement of the A.B.C. "Scorpion" engine results in a smooth deck without obstructions. Behind the pilot's seat is room for mails or luggage. The controls are of normal type, with a "joy stick" for ailerons and elevator and a foot-bar operating the rudder.
   The tail surfaces consist of a fixed tail plane, set very low on the fuselage, to which is hinged a one-piece elevator, and of a fixed vertical fin supporting a very tall and rather narrow rudder.
   The undercarriage is of the “split " type, with plain rubber cord shock absorbers.
   A neat cowling surrounds the central portion of the "Scorpion" engine, and as the petrol tanks are situated in the wing, direct gravity feed is available. A small spinner on the propeller boss serves further to streamline the "nose" which looks fairly "clean."

Specification

   Following are the main characteristics of the Mauboussin P.M.4 :-
   Wing span 10 m. (32 ft. 10 in.).
   Length, overall 4-40 m. (14 ft. 5 in.).
   Height 1-85 m. (6 ft. 1 in.).
   Maximum chord 1-5 m. (4 ft. 11 in.).
   Wing area 10 m.2 (107-6 sq. ft.).
   Engine A.B.C. "Scorpion."
   Normal power 34 b.h.p.
   Weight of machine, empty 185 kg. (407 lbs.).
   Normal load 115 kg. (253 lbs.).
   Normal loaded weight 300 kg. (660 lbs.).
   Maximum gross weight 340 kg. (748 lbs.).
   Wing loading 30 kg./m.2 (6-13 lb./sq. ft.).
   Power loading 8-8 kg./h.p. (19-4 lbs./h.p.).
   "Wing Power" 3-4 hp./m.2 (0-315 h.p./sq. ft.).

Estimated Performance

   Maximum speed 155 kms./hr. (96-25 m.p.h).
   Climb to 1,500 m (4,920 ft.) in 7 mins.
   Ceiling 7,000 m. (23,000 ft).

   During actual trials, the top speed did not reach more than 147 kms./hr. (91-25 m.p.h.), but the propeller fitted on this occasion was not quite suitable, and reduced the engine speed to 2,150 r.p.m., which would correspond to about 31-5 b.h.p. With the new propeller being produced, the engine speed should go up to 2,550 r.p.m., and allow the engine to develop 38 b.h.p. On climbing tests, a height of 1,000 m. (3,280 ft.) was reached in 5 mins. 25 secs., and an altitude of 2,000 m. (6,560 ft.) in 12 mins. 5 secs. Even these figures, however, are by no means bad, and the P.M.4 appears to be a very efficient little machine. Until further performance figures are available, there is little purpose in calculating the "Everling Quantities." It is of interest to note, however, that the top speed actually attained, assuming the engine to have developed 31-5 b.h.p., gives a "high-speed," figure of 18-5, which is quite good.

Flight, January 1932

The Mauboussin M.11 Monoplane

   REFERENCE was made a short time ago to the long solo flight made by Rene Lefevre in a Mauboussin monoplane with 40-h.p. Salmson A.D.9 engine from France to Madagascar. At the time details of the later stages of the flight were not available, but the information has now come to hand, as well as some particulars of the machine used by Lefevre, and as the flight was a very fine one, it is thought that a few notes on it and on the machine may be of interest.
   The earlier stages of Lefevre's flight were dealt with in the previous reference, but will be included here for the sake of completeness. The machine was standard in all respects except for the fitting of extra fuel and oil tanks for the larger amount of petrol which it was desired to carry in order to increase the length of stages. The weight of the extra fuel took the place of that of the passenger normally carried.
   Leaving Cannes on December 3, Lefevre reached Gabes, having flown via Corsica-Sardinia and Tunis. On December 4 Benghasi was reached, but bad weather detained Lefevre until December 6, when he covered the stage Benghasi-Mersa Matruh. Wadi Haifa was reached on December 7, the route being via Cairo. The next day the flight was continued to Khartoum, and to Juba on December 9. Juba-Kisumu was flown on December 10, but then bad weather again held up Lefevre until December 12, when he flew from Kisumu to Mombasa. On December 13 Mozambique was reached, via Lindi, and the final stage, Mozambique-Tananarive, was completed on December 14, the total journey having occupied a lapsed time of 12 days, and the actual flying time being 10 days. In Madagascar, M. Lefevre will try to utilise the machine for commercial work on a small scale, the machine having a pay load of about 220 lb., and a fuel consumption of approximately 2 3/4 gallons per hour at a cruising speed of some 75 m.p.h.

The Machine

   The Mauboussin M.11 is not a new type, two having been entered and one started in the International Touring Competition (Circuit of Europe) in 1930. On that occasion, however, the machine had bad luck, and did not reach any of the British controls, so that it will be something of a stranger to most FLIGHT readers. The designer of the M.11 is M. P. Mauboussin, whose offices are at 3, Rue de Choiseul, Paris. M. Mauboussin does not build his own machines, but has them built for him by M. Louis Peyret, whose name will be very familiar to our readers as that of the man who designed and built the Peyret glider on which some years ago the late M. Maneyrol won the Daily Mail Gliding Competition at Firle Beacon. A previous type, the M.10, was a single-seater very similar in general appearance, but fitted with a British A.B.C. "Scorpion" engine. A more recent type, the M.12, is an open low-wing cantilever monoplane, also fitted with the Salmson A.D.9 engine.
   The M.11 is, as the illustrations show, a high-wing cantilever cabin monoplane, the outstanding features being a wing of high aspect ratio and pronounced taper, and an extremely short fuselage. The short lever arm of the tail is, however, made up for to some extent by tail surfaces of considerable area and, like the wing, of high aspect ratio. For all that one would rather imagine the machine to be somewhat sensitive on fore-and-aft and directional controls.
   Structurally, the M.11 is a very simple, straightforward piece of work, with wood, and particularly plywood, forming the greater part of the structure.
   The fuselage is of the flat-sided type with plywood covering on a light skeleton of longerons and frames. The cabin has two seats, slightly staggered in relation to each other, and the view forward is fairly good by virtue of the low position of the thrust line relative to the level of the pilot's eyes. Behind the seats, and within easy reach of them, is the luggage space, which is of considerable size.
   The cantilever wing is a one-piece structure, consisting of two main box spars, light ribs, and a plywood planking. It is attached to the fuselage by four bolts only. The wing section is of the bi-convex class, with nearly stationary centre of pressure. The ailerons are of large span but small chord.
   An undercarriage of the simple "split" type is fitted, and the track seems a little narrow for the wing span. The tail skid is swivelling, rubber cords being used for springing and also to limit the directional movement of the skid.
   The Salmson A.D.9 engine is mounted on a welded steel tube engine bearer attached to the fuselage by four bolts, and separated from the cabin by a fireproof bulkhead. Petrol is carried in two tanks in the wing, the standard capacity being 60 litres (13.2 gall.). For his flight to Madagascar M. Lefevre had large tanks installed in the cabin so as to increase the range to 1 500 km. (930 miles). As the normal tankage is 13 gall, and the average consumption at a cruising speed of 75 m.p.h. is about 2 3/4 - 3 gall, per hr., the machine has a still-air range of about 330 miles.
   The standard type M.11 has a tare weight of 320 kg. (700 lb.), and as its permissible gross weight is 550 kg. (1,210 lb.), the disposable load is 510 lb. This may normally be made up as follows :- Pilot and passenger, 350 lb.; petrol and oil, 100 lb.; luggage, mails or other pay load, 60 lb.
   The main overall dimensions are shown on the general arrangement drawings. The length is 18 ft.; the wing span 38 ft. 6 in., and the wing area 159 sq. ft. Thus the wing loading is 7.6 lb./sq. ft. and the power loading (on 40 h.p.) 30 lb./h.p. This is a fairly high power loading, but normally the machine is not loaded up to its maximum permissible gross weight and the loading is slightly reduced.
   The performance of the Mauboussin M.11 is not spectacular, naturally. With such loadings one would not expect it to be. The maximum speed is, however, about 93 m.p.h., which gives an Everling "High-speed Figure" of 21.3, a value which indicates that the minimum drag coefficient is low. The cruising speed is approximately 75-80 m.p.h., and the landing speed is given as 40 m.p.h.
   By his flight Lefevre demonstrated that the machine is certainly capable of something more than flying around above an aerodrome in spite of the relatively low cruising speed. The machine should be very economical to run, as the fuel consumption is rather less than 3 gall, per hr. at nearly 80 m.p.h., so that the mileage per gall, is in the neighbourhood of 26. If the cost is divided between the two occupants this must be regarded as cheap touring.
   The service ceiling of the M.11 is about 14,750 ft., which altitude is reached in 50 min. The first 3,000 ft. takes about 7 min.