Flight, April 1925

THE LOENING METAL AMPHIBIAN

   A NEW type of metal amphibian, according to our American contemporary Aviation, the Loening Amphibian, which has been secretly under development for over a year, made its first public appearance on January 18, at Boiling Field, Washington, D.C. This ship, the first of an order of ten being built for the U.S. Army Air Service, was delivered by air, piloted by Lieut. Wendell H. Brookley, who flew the machine from the Loening factory on the East River, New York City, to Mitchel Field. From there he made the cross-country trip to Boiling Field. It was the first cross-country flight ever made by an amphibian flying boat in America. Lieut. Brookley's trip was without incident, and he reported that the new craft handled well in every way.
   The following day Lieut. Brookley demonstrated the capabilities of the Loening Amphibian to the Lampert Aircraft Investigating Committee with a masterful exhibition of flying. Taking off from the field with Fred Heckert, aeronautical engineer of McCook Field, as a passenger, Brookley landed shortly after to show the committee the adaptability of the craft as a land plane. Taking off again, the pilot folded up the landing wheels, and sideslipped down to the Naval Air Station at Anacostia which adjoins Boiling Field.
   Four landings in the water were made altogether, and then, seeing Capt. Robert Oldys of the office of the chief of Air Service idling about in the air in a De Havilland, Brookley climbed and came alongside. Both pilots then threw the throttles wide open, and came down the field wing to wing. Soon Capt. Oldys was far outdistanced and the huge amphibian had beaten the D.H., the inverted Liberty motor in the amphibian turning up 1,700 r.p.m. for a speed of 127 miles per hour.
   Considerable interest is attached to this machine in aviation circles, as it represents a somewhat daring and novel design. For about the first time in the development of aeroplane design, the ordinary tractor type of biplane has been modified, so that the machine is capable of landing on either land or water, with ability to start from or alight on either, at a moment's notice. No extra floats or other devices are used, as the new design obtains its amphibious characteristics by the shape of the main fuselage body itself, the bottom of which is shaped like a flying boat hull, while the upper portion follows the lines of the usual tractor fuselage. To this is attached a folding landing gear, an ingenious device which is operated by an electric motor - the pilot merely throwing a switch in order to raise the wheels for water landing, or to lower them for alighting on the land.
   As already demonstrated in flight, the new Loening Amphibian, in performance of speed and manoeuvrability, compares favourably with other aeroplanes of the same weight equipped with Liberty motors, such as the D.H. But the deeper metal body and the unit construction give it a strength and rigidity which should greatly increase the safety of the crew in case of accident. In the sand test, conducted by the Air Service at Dayton, this body stood up without failure to a load of three or four times what is customarily applied.
   In addition to the metal covering of the entire hull and body, the interior construction of the wings is largely metal, duralumin being the chief material used.
   One of the most interesting features of the machine is the use of the Inverted Liberty Motor. This development places the bulk of the engine cylinders, etc., below the line of thrust of the propeller, so that clearance for the propeller is more readily obtained, and at the same time, the centre of gravity of the weight is lowered several feet.
   The Loening Amphibian weighs 3,300 lb. empty and 4,000 lb. loaded. It has seats for a crew of three and a gas capacity of 140 gallons, sufficient for a non-stop flight of 700 miles.
   Another interesting feature of the machine is that the forward projection of the boat-shaped body protects the propeller if landings have to be made in thick wheat fields or bushes, and prevents the machine from turning over on its nose, when hitting obstacles.
   The new machine was designed and built by the Loening Aeronautical Engineering Corporation of New York.

Flight, May 1925

THE LOENING AMPHIBIAN

   IN our issue for April 2 last we published a brief report on the tests with the Loening amphibian, and this week we are able to give some further particulars, together with illustrations and general arrangement drawings, of this interesting machine, which have kindly been furnished by Mr. Loening.
   The announcement that the U.S. Navy Department of the MacMillan expedition to the Arctic is using the Loening amphibian calls attention prominently to this new type of aircraft, which has been under secret development for over two years for the American Government, at the new aircraft plant of the Loening Aeronautical Engineering Corporation at 31st Street and East River, New York City.
   The versatility and general usefulness of this new type of machine is indicated by the fact that the Army Air Service of the American Government has ordered it for use in Panama, Hawaii, and the Philippines, as well as along the coast; and the Marine Corps has ordered the same type for general use, in Haiti and the Caribbean Sea; and the Navy Department of the American Government has ordered the Loening amphibian, for use on aircraft carriers and battleships, as the standard observation machine of the navy. In addition to this, it is said that the American Post Office Department is also interested in this machine, so that there probably has never been a design of aeroplane developed, either in Europe or America, which appears to have a wider application than does the Loening amphibian - chiefly due to the fact that, in addition to being an amphibian, the Loening type has shown itself to be an exceedingly good seaplane, and, much to the surprise of aviation experts, has equally shown itself to be a very good land type 'plane, even if it was to be used exclusively over land.
   Grover Loening, the inventor of the new 'plane, has been consistently working for a long time perfecting this type of aircraft. Loening, who is one of the most experienced aircraft designers and engineers in America, was awarded the Aero Club of America trophy, two years ago, for the greatest development in aviation, and is this year a prominent contender for the new Wright medal, which is to be awarded for the greatest current achievement in aviation. Many aviation experts believe that Loening's new type of amphibian, due to its very successful tests, represents one of the most practical and useful developments in aviation since the War, and one that is declared to be entirely original and with a wide field of use.
   The principal idea in the Loening Amphibian is the use of the inverted type of aircraft engine, placing the propeller thrust at the top of the body and thus including the entire body with the engine mount in the nose to form a compact unit hull, carrying passengers, load, petrol, and all equipment. The landing gear, which is mounted to this hull, folds into it by the operation of an electric motor, switched on by the pilot. This hull body is made exceptionally strong, entirely covered with metal, and so shaped as to give remarkable seaworthiness which has been proved by tests in rough water carried out this winter in the Atlantic Ocean off Norfolk, Virginia, by a special Board of Army and Navy Pilots, and representatives of the National Advisory Committee.
   The crew sit well back and in the upper part of this unit body, where they are protected from spray and in a much safer position than has been, heretofore, found possible on flying boats. There exists, therefore, a very definite distinction between the Loening type of amphibian, and other types of aeroplanes designed for land and water use, such as the Vickers Amphibian, etc., which, like two or three machines of that type in America, is, practically speaking, an orthodox type of flying boat, to which wheels have been added, but carrying the engine up above between the wings - in a comparatively dangerous position in the event of an accident.
   In flying tests that have been made by the Army Air Service the past few months, the flying qualities of the new machine were found to be quite remarkable, and to equal in every way the ordinary land type of aeroplane of the same weight and power - so that enthusiasts for the new Loening type point out that it will very likely render the old limited type of land machine obsolete, as, not only is there no loss in performance or manoeuvrability due to the new type, but there is a definite gain in strength against crashing, and very much more room, made available for added loads to be carried. Since this type of machine can also land with equal ease on soft snow or hard ice by merely carrying retractable skis instead of retractable wheels, it becomes an ideal 'plane for Polar exploration, and, in fact, its development makes the present plans for the MacMillan Expedition extremely practical.
   The Loening Amphibian is fitted with an inverted 400 h.p. Liberty engine. It weighs 3,300 lbs. empty, and carries a load of 2,200 lbs., including pilot, observer, cameras, radio and 250 gallons of petrol, which is sufficient for a flight of over one thousand miles. In the test conducted at the Army Air Service Engineering Division at McCook Field, Dayton, Ohio, this 'plane has recently demonstrated a high speed of 122 miles an hour, and a ceiling of 14,000 ft. The machine is readily hoisted aboard a ship and launched in the water and may either be moored in a bay, or with its wheels down run up on to a beach. It handles in every way exactly like a seaplane, or exactly as a land 'plane, depending entirely upon the desire of the pilot.
   While the Liberty engine is fitted in this machine, any twelve cylinder motor of approximately 400 h.p., weighing about 900 lbs. (400 kgs.), in which the cylinders project through the crankcase, can readily be modified for use on this 'plane. Among such engines may be mentioned the "Eagle" Rolls (ungeared), Renault, Lorraine-Dietrich, Fiat, etc. The only major change made in the Liberty motor for this work, was the installation of oil collecting chamber and sump ahead of the distributors of ignition mounted on the camshaft.
   Last February, the first public demonstration of the new type was made in Washington, D.C., with Lieut. Wendall H. Brookley of the Army Air Service giving an exhibition of flying before the Aircraft Investigating Committee of Congress, and which at the time was commented upon as being quite a remarkable display - the machine being equally at home on Boiling Field, or in the Potomac River. It was at this time that General Mitchell stated to the Committee that in his opinion this machine represented the most satisfactory solution that he knew of for this difficult type of 'plane, and represented a real advance in aircraft engineering for which there would be great promise.

Flight, December 1927

THE LOENING OL-8 AMPHIBIAN
The Latest Development of a Successful American Machine

   SINCE the maiden flight of the first Loening Amphibian, in June, 1924, over 1,600,000 miles of flying have been accomplished by these machines. This very original design of amphibian - with which our readers should be well acquainted, since we have frequently dealt with it in FLIGHT - has become in a space of three years the standard service plane of this type for the U.S. Army Air Corps, the U.S.Naval Air Service, the Marine Corps and the U.S. Coast Guard, and is now a familiar sight at all American air stations.
   It is, perhaps, a remarkable example of the successful step-by-step development of an original idea (to which the constructors have persistently adhered) from the first thought on paper to the finished product itself - now being produced at the rate of two a week.
   During the development of this amphibian - the 100th machine will shortly be delivered - a vast amount of practical experience has been gained, which should prove of great value to the Loening Aeronautical Engineering Corp. of New York, when this company enters the field of commercial aviation, which, it is reported, will shortly be the case.
   Particular interest, therefore, attaches to the new Loening Amphibian, known as the OL-8, fitted with a 425-h.p. Pratt & Whitney "Wasp" air-cooled radial engine, which has very successfully completed all of its tests for the U.S.Navy Department.
   The outstanding features of, and advantages claimed for, the Loening Amphibian, which differentiate it so clearly from other types of aircraft, are, briefly - the patented Loening feature of the unit hull and body - a sort of combination of flying-boat and tractor fuselage - in which the functions of both are performed to the best possible advantage; the composite hull construction - a wood frame with metal-covering sheets bolted thereto; the practical and rugged amphibian gear and the good flying qualities, which are described as giving the flying-boat the flying characteristics of the normal land 'plane.
   The Loening hull is undoubtedly the most interesting feature of the whole machine. The general arrangement of the hull may be followed by reference to the accompanying illustrations from which it will be seen that a short central flying-boat type of flotation gear is employed, upon which is built up a more-or-less orthodox type of fuselage - both neatly merging one into the other. This original design was evolved by Grover Loening in 1924, and has from the first given very satisfactory results.
   The Loening type of composite wood and metal construction was first used in experimental flying-boats designed by Loening in 1911 and 1912, and again in 1914 on the seaplanes built by the Dayton Wright Co. In this type of construction the framework is wood, fastened together with metal gusset plates the entire framing then being covered by sheet metal bolted to the wood. From experience it was found, however, that great care had to be taken to separate the duralumin sheet and the wood by a layer of fabric impregnated with bitumastic or marine glue.
   The use of bolts instead of rivets or wood screws is the result of a very careful study, and is particularly desirable in that it makes the protection of the bolt against corrosion in salt water much easier, because each individual bolt can receive numerous coatings of enamel or bitumastic. Furthermore, in being fastened to the hull, it is not hammered like a rivet, and therefore is not likely to lose its heat-treatment against corrosion. It is claimed, therefore, that any amount of protection can be given the bolts, which is not the case with rivets. The wood frame has enough resiliency to take up the severe local strains of the land operation of this machine to prevent leaks from developing - which has always been a serious cause of trouble in amphibians.
   One other advantage of this form of construction is the sealing of the joints by means of fabric tape impregnated with a special water-proof glue which, clamped between the metal covering and the wooden frame with duralumin bolts, gives a remarkably watertight result - particularly as the wood, when damp, swells sufficiently to give all the advantages of tightening found in wooden hull construction.
   In the OL-8 hull, the frame consists essentially of two longitudinal girders of the Pratt truss type, cross connected by bulkheads, subdividing the hull into numerous watertight compartments.
   The spruce longerons of this framework and the diagonal members are all joined by simple, fiat gusset plates of dural, bolted throughout with duralumin bolts, giving an excellent job for production. The lower part of the hull frame, and the upper longerons and diagonals framing the main fuselage section, are all built as one unit, the lower part, however, having a curved "tumble-home" side, and the upper body section a flat side with a rounded top.
   The bottom is specially reinforced to withstand contact with the deck-alighting gear on aircraft carriers, and in addition, the hull is specially braced internally and externally to withstand the catapult stress incident to being shot from the U.S. Navy's powder catapult.
   The pilot's seat is located well forward, between the wings, where good visibility is provided, especially for deck landings. Immediately behind is the gunner's cockpit, while below, in the deep hull, there is a cabin for the observer or wireless operator, who has a good range of vision below the wings through windows in the sides of the hull.
   As regards the wing construction on the OL-8, this is also composite in that the ribs are all made of dural and the spars of spruce. This gives an excellent combination for a seaplane (particularly with the advent of the new non-corrosive duralumin called “Alclad," which is used on the ribs) because the maintenance difficulties of the small parts on a seaplane of glued-up wooden ribs coming apart are entirely solved - and yet the reliability and lightness of wooden ribs are maintained throughout.
   The interplane struts consist of welded steel "N" struts with the usual streamline wires bracing the two-bay wing, all being held by simple flat-plate metal fittings which project through the wing, but which are carefully boxed in so that no salt water can enter the wing around the fittings. Both top and bottom 'planes have a dihedral angle of 3 degs. and a stagger of 12 in., but there is no sweep-back. Ailerons, of high aspect ratio, are fitted to top and bottom 'planes, the lower ailerons being operated by cables in the bottom wings, and the upper ailerons being actuated by struts from the lower ones.
   The Loening 10A wing section is employed on the OL-8, a section, the details of which have never been published, developed by the Loening engineers, that has given exceptional results. It may be of interest to note, in passing, that this is the same section which, applied to D.H.4-type machines, with no other change, increased their speed over the R.A.F. 15 section by over 13 m.p.h., decreased the landing speed 11 m.p.h., and increased the ceiling 2,000 ft. Several D.H's. are now in service of the U.S. Government, using Loening 10A wings - the most notable being a special D.H. used by Major E. H. Brainard, Chief of the U.S. Marine Corps Aviation Service.
   The wings have a high safety factor, and all forms of "stunting" can safely be carried out on the Loening amphibian fitted with these wings. Special fittings that have been devised in the development of the amphibian enable a very quick set-up and take-down.
   Both fin and rudder are metal-covered throughout, the rudder, which has much the same construction as the hull, being exceptionally large. The elevators and stabiliser are of usual wood and fabric construction, braced by diagonal steel struts, giving a very rigid structure on torsion. The stabiliser is not adjustable in flight, but, what amounts to the same thing, a spring adjustment on the elevator controls relieves the pilot of tail-heavy or nose-heavy balance.
   Another characteristic feature of the Loening amphibian is the patent landing gear, on which some considerable amount of research and experiment has been applied, with the result that it is now an entirely satisfactory and practical proposition.
   In this the wheels are pivoted on frames, raised and lowered laterally with respect to the hull. A thrust member carries the landing gear load from the top of the wheel frames, and the upper end of this thrust member - by being operated upon a slide tube through cables or screw shafts - rotates the wheel frames around an axis at the chine of the hull upwards and into the sides of the hull, so that the entire mechanism is folded away with the exception of half a wheel. The principal advantage of this folding away is not so much in the reduction of air resistance - which is somewhat negligible - but in the reduction of water resistance for take-off, and in bringing the landing gear mechanism away from possible fouling with driftwood or debris, which would tend to jam it. As a safeguard, also, against the latter contingency, a cover plate, attached to the axle, folds up over the opening in the hull, from the chine upwards, in order to prevent water, driftwood, etc., from sweeping in and so jamming the gear. The gear is operated either by an electric motor, with suitable drive shafts, or by a simple hand crank and cable system.
   Spring skids are also mounted on the wing-tip floats, which not only protect the floats from driftwood in the water, but they also protect the floats from injury on the land. At the rear of the main section of the hull is a "husky" tail skid of steel tubing bearing up against rubber disc absorbers; on the skid is mounted a detachable shoe for wear and tear.
   The Pratt and Whitney "Wasp" engine is mounted in the "nose" of the fuselage - or its equivalent - in a somewhat unusual manner. In addition to steel tubes running fore and aft to the longerons from the flanged dural engine plate, there are two vertical struts extending down, and slightly forward, from the latter to the hull. These struts, which are braced by cross wires, transmit the engine load directly to the front part of the hull, and, it is claimed, greatly reduces the usual radial engine vibration. The cowling round the engine has been reduced to the minimum so as to give ample air cooling for tropical work, while the usual rotary shutter is provided at the central portion of the cowling.
   The oil tank, of 10 gals, capacity, is located behind the engine, and the petrol tank, of 140 gals., is located in the lower part of the hull.
   Dual control is provided, wheel type in the forward and stick type in the rear cockpits. The OL-8 is exceptionally controllable under all conditions - turning on rudder alone, the machine takes up the correct bank without the aid of the ailerons, while the longitudinal balance is also very good. The quick take-off from water is another feature of the OL-8 - this generally taking about 10 seconds, with full load.
   Although primarily designed for Army or Navy observation work, the Loening OL-8 is also particularly suitable for other purposes, such as aerial photography - it will be remembered that Loening amphibians were successfully employed for the aerial survey of the Rainy Lakes and Canadian border, in Cuba, Venezuela, and Alaska.
   The principal characteristics of the Loening OL-8 are :-
   Span 45 ft.
   O.A. length 35 ft. 2f in.
   Height (wheels down) 12 ft. 11 in.
   Chord 6 ft.
   Gap 5 ft. 11 1/4 in.
   Stagger 1 ft.
   Dihedral and incidence 3°.
   Wing area 502 sq. ft.
   Area of ailerons 60 sq. ft.
   ,, ,, elevators 28 sq. ft.
   ,, ,, rudder 17-4 sq.ft.
   ,, ,, stabilizer 43-4 sq. ft.
   ,, ,, fin 15-8 sq. ft.
   Weight, empty 3,253 lb.
   Weight, laden 5,253 lb.
   Weight per h.p. 12-3 lb.
   Weight per sq. ft. 10-4 lb.
   Speed range 50-124 m.p.h.
   Climb in 10 mins. 5,500 ft.
   Ceiling 13,000 ft.
   Range (cruising) 560 miles.