Flight, January 1928

THE CENTRAL STATES "MONOCOUPE"
An American Light 'Plane

   SOME little while back the Central States Aero Co., of Davenport, Iowa, U.S.A., constructed a light monoplane, designed by Don Luscombe and Clayton Folkerts, of that firm. The performance of this first machine was so successful that the company at once put the "Monocoupe" (as it is called) into production, and the output at present is one a week.
   The "Monocoupe" is a high-wing monoplane - a type that has become, quite fashionable now in the States – with enclosed cabin-fuselage, and fitted with a 75-h.p. Detroit "Air-Cat" 5-cyl., air-cooled, radial engine, and seating two side-by-side. It has a maximum speed of 102 m.p.h., and a stalling speed of 48 m.p.h.; the cruising speed is 80 m.p.h. with a fuel capacity of 20 gals, it has a range of about 400 miles.
   Its design load factors are 6-5 for high incidence; 4-5 for low incidence; 2-5 for inverted flight; and 2 for nose-dive condition. In some places, owing to the small size of the machine, it was necessary to work with the minimum sizes, but in most main members, the strength is in excess of the required load conditions. For instance, the ribs have a margin of safety of 20 per cent.; the fore and aft wing struts are 14 per cent, and 12 per cent, respectively over required load factors, while the weakest member of the fuselage is 13 per cent. over. The weight empty of the "Monocoupe" is 650 lbs., and laden, 1,134 lbs.
   The wings, which have a Clark "Y" section, are in one piece, 30 ft. span by 5 ft. chord (or an aspect ratio of six), and are externally braced from the fuselage by two pairs of steel V struts. They are of wood construction, fabric covered, the spars being of I-section selected spruce, the front spar being located at 15 per cent, of the chord, and the rear spar at 65 per cent.; the spars are spliced at the centre by a vertical cut having a slope of 1 in 12. The trailing edge is of 16-in. piano wire.
   The ribs are built up of 1/8-in. basswood webs reinforced by spruce cap strips, large rectangular lightening holes being cut in the webs, and each rib, which is spaced 14 in., weighs 7 1/2 ozs. The compression ribs are similar, except that they have no lightening holes and are reinforced by rectangular compression members glued and nailed to each side and centering at the drag bracing fittings; the solid webs stiffen the spars against twisting.
   Both front and rear bracing struts come together at the bottom of the fuselage, the cross member of the latter at this point consisting of a 1 in. by 0-049 steel tube, 32-5 in. long and having a margin of safety of 3-58 per cent, under the maximum compressive load and 4-46 per cent, under the maximum tensile load induced by the struts.
   The brace-strut lower fitting is attached to the transverse tube of the fuselage by a long strip weld to insure full use of the strut strength; a central vertical "fin" prevents the fitting from bending under compressive loads. The fittings securing the struts to the spars are fastened by two 5/16- and two 3/16-in. nickel steel bolts, the strut bolts being 3/8-in. of the same material. The single drag wire bracing is of the conventional type, No. 10 piano wire being used throughout.
   The wing is attached to the fuselage by four 5/16-in. nickel steel bolts passing through single lugs extending from the spars and passing through a box fitting at the upper fuselage joints.
   The ailerons, of rectangular plan form, are attached directly to the rear wing spar by three pin hinges, both the spar and torque member of the aileron being reinforced at the hinge points. The ailerons are comparatively small, having an area of 12 1/2 per cent, of the main wing area.
   First-grade aeroplane fabric is employed for the wing covering stitched to the ribs at intervals of 5 in. outside the slipstream area and at 3 in. inside; six coats of nitrate dope are applied to protect the surface.
   All tail surfaces are made of welded 10255 tubing, the horizontal stabilising surface being exceptionally strong; the tail is braced by 10-32 streamline wires. Rudder, elevators and ailerons are unbalanced, and the controls are of the conventional 1/8-in. flexible cable-and-pulley type with stick and pedal control.
   The fuselage is of welded-steel tubing built up into a Warren truss, giving ample room forward in the vicinity of the cabin, and tapering sharply in depth and width at the rear. All tubing is 20-gauge, except for an 18-gauge member, which takes the loads from the wing struts; the landing gear and rudder posts are also heavier.
   The cabin - or enclosed cockpit - is very roomy, measuring 2 ft. 8 in. wide, 3 ft. 7 in. high, and 2 ft. 6 in. deep. It is upholstered with "Ca-Vel," and has "Pyralin" windows. A door is provided on either side, according to which side the throttle control is located. Normally, the main controls are situated on the left, but dual control can be fitted, if desired. Pilot and passenger sit side-by-side, the seats being slightly staggered, with the passenger's seat to the rear.
   Six chrome molybdenum steel tubes welded to a ring at four points comprise the engine mount, which can be detached by removing four 5/16-in. nickel steel bolts, which are under double shear.
   The Detroit "Air-Cat" engine develops 75 h.p. at 2,000 r.p.m. and weighs 220 lb.; it is equipped with two Scintilla magnetos and a Stromberg carburettor. Petrol is fed by gravity from two tanks in the wings, the oil tank being located behind the engine and the oil circulated by an integral gear pump. The exhaust is led from each cylinder by 2 1/4-in. flexible steel tubing to a steel exhaust pipe located under the fuselage.
   A conventional V-type landing gear, with straight axle and rubber shock-absorbers, is fitted, while the tail skid is of the full floating type, of 1-in. steel tube.
   The principal characteristics of the "Monocoupe" are :-
   Span 30 ft. 0 in.
   Chord 5 ft. 0 in.
   O.A. length 19 ft. 9 in.
   Height 6 ft. 3 in.
   Wing area 150 sq. ft.
   Weight, empty 650 lb.
   Weight, laden 1,134 lb.
   Weight per square foot 7-58 lb.
   Weight per h.p. 15 13 1b.
   Speed range 48-102 m.p.h.

Flight, January 1929

THE CHICAGO INTERNATIONAL AERONAUTICAL EXPOSITION

   Mono Aircraft Inc. of Moline, Ill., exhibited a "Monocoupe" light 'plane fitted with a 60-h.p. "Velie" engine - the same type of machine which has been introduced into England by Mr. Irving. The "Monocoupe" is a two-seater (side-by-side) high-wing cabin monoplane, not unlike the Belgian Demonty Poncelet and it has already obtained a certain amount of popularity in America. Its fuselage rises sharply from the tail up to the straight wing, that portion immediately below the latter being cut away to receive a large window extending right round from sides to front and thus forming a roomy cabin. The wings are braced by a pair of struts on each side, extending from the lower longerons up to the wing spars. A non-axle type undercarriage is fitted, and this can, we believe, be changed for floats. Characteristics :- Span, 32 ft.; o.a. length, 20 ft.; weight empty, 795 lbs.; total weight, 1,350 lbs.; speed range, 37-97 m.p.h.; climb, 800 ft. per min.; ceiling, 13,000 ft. cruising range, 500 miles. This firm also exhibited two other types - the "Monoprep," a training machine very similar to the "Monocoupe," but with open cockpits; and the "Monocoach," a four-seater and larger edition of the "Monocoupe" fitted with a 170-180-h.p. Velie.