G.Swanborough, P.Bowers United States Military Aircraft Since 1909 (Putnam)
The M-8 design originated in the spring of 1918, when Grover C. Loening was unofficially asked to produce a two-seat fighter superior to the British Bristol F.2B, and initial procurement was expedited by having the Wright-Martin Company request the Loening Aeronautical Engineering Corporation to build two prototypes (40121, 40122) as test beds for the Wright “H” engine, an Americanized version of the 300-h.p. French Hispano-Suiza. The M-8 met all performance expectations, and in spite of certain structural and aerodynamic problems, was slated for a 5,000 machine production order which was cancelled by the Armistice.
Span, 35 ft. 0 in.; length, 25 ft. 0 in.; wing area, 290 sq. ft.; Gross weight, 2,600 lb.; highspeed, 151 m.p.h.
G.Swanborough, P.Bowers United States Navy Aircraft Since 1911 (Putnam)
Loening M Series
The Loening monoplanes were a daring innovation in their day, since the field of military aviation in 1918 was dominated almost entirely by biplane-minded pilots, engineers and procurement personnel. Grover C. Loening, who had acquired an aeronautical engineering degree from Columbia University in 1911 by virtually inventing the course, was able to see the inherent speed and structural simplicity advantages of the monoplane and had the tenacity to fight for his beliefs against adamant opposition. Loening got his chance in 1918, by which time he was a thoroughly experienced engineer, having worked for the Wright Brothers, been chief engineer of the Army Flying School in San Diego, and then chief engineer of the Sturtevant Aeroplane Co. After forming his own company in 1918, Loening was asked to design a two-seat fighter that would out-perform the famous British Bristol Fighter. The result was the M-8, a strut-braced high-wing monoplane built around the new 300 hp Hispano-Suiza engine just then going into production in the United States as the Wright H-3.
In addition to being a monoplane in a biplane's world, the M-8 had a number of advanced features. One was the radiator installation, which was mounted in a tunnel beneath the engine instead of surrounding the propeller shaft or being a separate bolted-on item outside the fuselage lines, as was customary. This feature was widely adopted by other high-performance military aircraft in the post-war years.
The parallel lift-struts connecting the wing to the lower longeron were fitted with wide fairings of aerofoil section that were expected to contribute lift. This feature was to become a trademark of the famous Bellanca monoplanes of 1925-40. With the upper longerons at the level of the wing, the rear gunner had an excellent field of fire for his twin 0.30-in Lewis guns. The pilot, of course, had the same unobstructed view above for fighting and could also see under the wing through windows below the longerons. The performance of the M-8 was such that a contract for 5,000 was placed, but the wholesale cancellations that followed the Armistice kept production models from being built for the Army.
The Navy, having taken a low-cost sample of Loening's basic monoplane design with three ultra-light Kittens (A442-A444) that were designed as ships' planes and were considered for quick disassembly and stowage aboard submarines, took an interest in the full-size fighter design after the war and ordered a single naval version as the M-8-0 (sometimes written as M-80). This was followed by orders for 46 production models designated M-8-0 and M-8-1 (M-81) which, although designed as fighters, were used for observation purposes. An additional six were ordered as M-8-1S twin-float seaplanes, and at least one of these was tested as an amphibian with wheels built into the bottoms of the floats.
Three practically identical models, designated LS for Loening seaplane, were also ordered, but the last two were cancelled. The single LS (A5606) was used to test the unique Richardson Pontoon which was in effect a standard float of somewhat greater than standard width split along the centreline. These halves were then moved apart to standard twin-float positions beneath the seaplane. The vertical inside face of each separate float was supposed to improve the water-handling characteristics of the combination, but nothing seems to have come of it and the experiment was dropped.
The Navy attempted to capitalize on the loudly proclaimed speed advantages of the monoplane by fitting one M-81 (A5791) with a special set of small wings for its entry in the 1920 Pulitzer race. Span was reduced by nearly 5ft, the chord was reduced by 2 ft, and the wide lifting-struts were replaced by thin streamlined steel tubes. The racer, flown by Lt B. G. Bradley of the US Marine Corps, developed a water leak early in the race which forced it out in the last lap after achieving a speed of 160mph around the closed course. It was ironic for Loening that after this misfortune the Navy pinned its racing hopes on biplanes and even kept a pair of triplanes in service for such purposes through the 1923 season. He was able to sell a handful of monoplane fighters and racers to the Army in the years 1920-2, but had to fall back on the traditional biplane in order to win significant orders and did not introduce another monoplane for over a decade.
TECHNICAL DATA (M-8-0)
Manufacturer: Loening Aeronautical Engineering Company, New York.
Type: Observation monoplane.
Accommodation: Pilot and observer.
Power plant: One 300hp Hispano-Suiza.
Dimensions: Span, 32 ft 9 in; length, 24 ft; height, 6 ft 7 in; wing area, 229 sq ft.
Weights: Empty, 1,623lb; gross, 2,068 lb.
Performance: Max speed, 145 mph; climb, 10 min to 13,900 ft; service ceiling, 22,000 ft; endurance 5.5 hrs.
Armament: Two flexible 0.30-in Lewis guns.
M-8-1: A5701-A5710; A5761-A5786.
Jane's All The World Aircraft 1919
Aeronautical constructional engineers, engaged during the war in experimental work for the U.S. Army and Navy, as the result of which they produced a fighting monoplane of highly original design end a ship-plane of very small dimensions.
THE LOENING M-8 MONOPLANE
It is stated that in its actual performance the Loening monoplane has, with the full two-seater fighter load, not only exceeded all the performances of other machines, but has with this same load equalled, if not exceeded, all of the performances of the very best European single-seaters with the same engine.
In the tests made by the manufacturer at Mineola, the machine showed a high speed of 146 m.p.h., and on one occasion climbed to 24.000 ft. in 43 min. with pilot, passenger, two hours fuel and considerable gun equipment, thus establishing an unofficial height record for two-seaters.
The new monoplane of the same type tested at Dayton by the U.S. Army snowed practically the same high speed, and climbed - with a live load almost equal to the weight of the aeroplane - 16,000 ft. in 18 min.
The outstanding feature of the machine is the manner in which the wings fasten to the upper body longitudinals, and ore braced by two enormous braces to the bottom of the body. This method of wing bracing bus so much simplified the construction of the machine, that it has permitted to cut in halves the structure weight.
A very interesting feature of the design proven by the tests made is the slow speed on landing and general buoyancy of the machine, despite the fact that the wing loading has gradually been stepped up to almost 12 lb. per sq. ft.
The wings, body, tail surfaces, landing gear, etc., are all -built of most approved spruce and metal fitting airplane construction. All metal fittings ore of stamped sheet metal, with practically no braced or welded parts, all joints are pin connected, particularly the joints of the main wing braces to the wings and body, which are free to move in any direction, so that vibration will not fatigue these members. In addition to which, all parts are readily adjustable for alignment.
Sand load tests that have been carried on exhaustively to prove the strength of the machine show a safety factor of 14 on drift stresses, and a safety factory of 8 on lift stresses.
All tail surfaces and fin surfaces, stabilizers, rudders, etc withstand on actual sand test a load of 35 lbs. per sq. ft. area.
It is claimed that the visibility afforded to the pilot is so complete that he has practically no blind spots at all. He can see either above or below the wings or to either side, and in addition to that can see quite well in the front, due to the narrowness of the body.
The Gun Range.
The gun range is also very good, particularly as the gunner can shoot forward, the only obstruction being the arc of the airscrew.
The deep body offers ample room for all kinds of military. equipment, oxygen tanks, wireless apparatus, cameras, etc, and in addition to that the arrangement of the cowls is such as to give the occupants ample protection against the wind without interfering with the view.
The construction has everywhere been studied so as to give maximum strength to all of the porta that ore vital due to damage from bullets. This is particularly true of the main braces supporting the wings which can bo half shot away before they will lose the safety factor of 8 provided.
It has been found that the machine lands very slowly, gets off the ground in 4 seconds from a dead start, and that in flight the machine is very easy to handle on all its controls in spirals, loops, barrel rolls, etc
The performances of the machine with full load are as follows:
Slow speed 48 m.p.h.
High speed 146 m.p.h.
Indicated ceiling, light load 26,000 ft.
heavy load 22,000 ft.
The principal characteristics of the Loening monoplane are as follows :
Main planes, total 238.9 sq. ft.
including ailerons 214.9 sq. ft.
Strut planes 24.0 sq.ft.
Ailerons (2) 24.0 sq.ft.
Fins (2) 8.8 sq. ft.
Stabiliser 14.9 sq.ft.
Rudders (2) 9.0 sq. ft.
Elevator 15.0 sq. ft
Weight, empty 1,328 lbs.
Fuel and oil 360 lbs.
Military load 680 lbs.
Total weight 2,368 lbs.
Engine, Hispano-Suiza, model H, developing 340 h.p. at 1,800 r.p.m.
Weight, including airscrew, 618 lbs.
Fuel consumption per b.p.hr., 0.53 lbs.
Altitude. Speed. Climb
Sea level 146 m.p.h 0 min.
20,000 ft. 20 min.
W.Green, G.Swanborough The Complete Book of Fighters
LOENING M-8 USA
Daringly innovative for its day, the M-8 two-seat fighter, flown for the first time in August 1918, was the first product of the Loening Engineering Corp formed earlier that year by Grover C Loening. Despite some prejudice against the monoplane configuration, the M- 8, designed around the new 300 hp Wright (Hispano-Suiza) Model H engine, was a braced shoulder-wing monoplane. Possessing an exceptionally low structural weight, the M-8 carried an armament of two 0.3-in (7,62-mm) Lewis guns in the rear cockpit, the gunner having an excellent field of fire. The M-8 was of wooden construction and two prototypes were completed. These demonstrated such outstanding performance that a contract was placed for 5,000 aircraft before the Armistice terminated plans for large-scale production. Although only the prototypes went to the Army, the Navy ordered a single example as the M-8-0, following this with orders for a further 54 aircraft (of which 36 were built by the Naval Aircraft Factory). Forty-six of these were of the M-8-0 and M-8-1 types, which, although designed as fighters, were used for observation purposes, the remaining six being completed as twin-float seaplanes under the Navy designation LS-1.
Max speed, 144 mph (232 km/h) at sea level.
Time to 6,500 ft (1 980 m), 5.2 min.
Empty weight, 1,663 lb (754 kg).
Loaded weight, 2,368 lb (1 074 kg).
Span, 32 ft 9 in (9,98 m).
Length, 24 ft 0 in (7,31 m).
Height, 6 ft 7 in (2,00 m).
Wing area, 238.9 sq ft (22,19 m2).