SINGLE-SEAT GRUMMAN FIGHTERS used for deck landings on American aircraft carriers. An interesting feature of these aeroplanes is the combination of biplane construction and retractable undercarriages. The wheels are drawn up during flight into recesses at the sides of the fuselage just behind the engines, which are of air-cooled radial type. Curtiss-Wright and Grumman aircraft designed on similar lines have for long been popular types in the American Air Services.
THE question of how far a country’s aerial strength is influenced by the productive capacity of her factories has been much disputed. Some authorities believe that productive capacity is a truer measure of air Strength than first-line numbers. If that is so, the United States of America are in an unassailable position, as they have factories capable of producing aircraft at high rates.
Since the expansion of the Royal Air Force in Great Britain was undertaken on an intensive scale, British factories have increased rapidly in size and number, and the British industry is now one of the largest in the world. This is a development based almost entirely on armaments. The development of the United States aircraft industry, on the other hand, is based almost entirely on commercial aviation. America seized the world lead in commercial aviation some years ago, largely because of her natural advantages. The distances are sufficiently great in the American continents to emphasize the advantages of travelling by air; moreover, the American Post Office was favourable to the carriage of mails by air. Although there have been no direct Government subsidies, the mail contracts may be said to have been somewhat analogous to the subsidies which are paid to European air transport companies.
With these advantages the American industry set to work not only to produce aircraft on a fairly large scale, but also to develop them technically. The United States have done much to press forward aircraft development during the past fifteen years.
To lay stress on this point, it is necessary to mention only one name — the name of Douglas. At the time of the England-Australia air race for the MacRobertson Trophy in October 1934 (see the chapter “The Influence of Air Racing”) the Douglas air liner had been much talked about in Great Britain, but had not been sufficiently tested to prove its qualities.
ONE OF THE MOST POWERFUL AMERICAN FIGHTERS is the XFM-I, a clever adaptation of the twin-engined low-wing air liner. The engine nacelles have been increased in size and the engines placed at the rear to drive pusher airscrews. This has left the forward end of the nacelles free for the provision of two gunners’ positions. Gunners’ positions are also provided on either side of the fuselage.
Before that the American aircraft manufacturers had surprised Europe with the Curtiss engine, which might be said to have been one of the first post-war high-speed engines. It was built for low frontal area. The Fairey Aviation Company in Great Britain, having appreciated the value of this feature, took it up and caused it to be introduced for a time into the Royal Air Force of Great Britain.
With the Douglas it was not engine development that was so interesting as airframe development, and especially the use of all-metal stressed skin construction in a low-wing monoplane with retractable undercarriage. Stressed skin construction (see the chapter “All-Metal Construction”) was not new, but it had not previously been adopted as a regular feature outside America. In the American fighting Services it was not in general use until after it had been extensively adopted in the American air liners.
In brief, then, it was American commercial aviation that led the way in technique and production. It is important to remember this in any computation of the American air services, both in the Army and in the Navy. For it is a condition unknown elsewhere. In most other countries military aviation leads the way and commercial aviation is a subsidized addition to it. In America the constructors of commercial aircraft are all the time in advance of the constructors of military machines.
Recently they have given further proof of this with the new commercial air liners which were designed for substratosphere operation (see the chapter “Pan American Airways”). The pioneer work was undertaken by American firms. Now the U.S. Army Air Corps has taken over the work, and is experimenting with a substratosphere aeroplane which is nothing other than a modification of a commercial liner in extensive use. The tricycle undercarriage for large machines has been tried first with a commercial air liner, and is now to be tried for bombing machines.
The Americans have retained the principle of two separate services, one for the Navy and the other for the Army, and the air forces are divided between them. As the naval air force is exceptionally strong, it will first be examined.
Five or six aircraft carriers are in use, among them the Lexington and the Saratoga. These aircraft carriers take a bigger complement of machines than the British aircraft carriers. The deck flying machines are supplemented by numerous catapult-launched machines, as they are in the British fleet air arm. An interesting feature of many of the deck flying machines used by the U.S. Navy is that, although they arc biplanes, they are fitted with retractable undercarriages. Their appearance in the air is therefore unusual. They have large-section front parts to their fuselages, and are powered by air-cooled radial engines. The wheels are drawn up into recesses at the sides of the fuselage not far behind the engine. Curtiss and Grumman machines conforming to this general idea have for long been in use. Although the American flying Services, like those of other countries, are now changing over from the biplane to the monoplane, there are still large numbers of biplanes in use. The new monoplanes range from single-seater fighters by Curtiss and Seversky to four-engined Boeing B-17B bombers. The Boeing bombers are noteworthy for their performance with load. Flying boats are included in the American Navy in fairly large numbers.
A FOUR-ENGINED BOEING B-17B BOMBER of the United States Army. These aircraft are noteworthy for their performance when carrying heavy loads. They have a top speed of over 250 miles an hour, carry a crew of nine and have five machine-guns. One gun position is in the nose and the other four positions are in the form of “blisters” in the sides, top and bottom of the fuselage. Four 1,0000 horse-power radial air-cooled Wright Cyclone engines are fitted which dive three-bladed constant-speed propellers. Split trailing-edge flaps, and retractable type undercarriage are used. The wing span is 105 feet, the length 70 feet and the height 15 feet.
At the present moment [autumn 1938] it is difficult to assess the numerical strength of the American flying Services. They are in process of rapid expansion, as are the air Services of other nations. In July 1938 the War Department in Washington announced that 2,320 first-line aircraft were to be on the strength by July 1940. Orders were being placed with this end in view.
Some fifty-two of the Boeing B-17B four-engined bombers already mentioned were placed on order and a number of Douglas bombers were ordered also. Other aircraft ordered for the expansion are Vultee YA-19 aeroplanes, which are fast single-engined bombers.
The Boeing bombers have a top speed of over 250 miles an hour and carry five machine-guns and a crew of nine. The twin-engined Douglas bombers have a maximum of over 225 miles an hour and at the time of the War Department’s announcement more than 250 of them had been bought.
The Vultee attack bomber is another example of the way in which commercial machines have been modified and thus turned into military types. This machine is a two-seater low-wing cantilever monoplane with an 850 horse-power Wright Cyclone engine. Pilot and gunner are accommodated in a “tunnel” type of transparent-topped enclosure somewhat similar to that used in the British Fairey Battle bomber. This has sliding sections over the two seats.
Four machine-guns are mounted in the wings to fire forward in the line of flight. Bombs are carried within the centre section and there is a rear gun on a movable mounting. The wing span is 50 feet, the length 37 ft. 6 in. and the maximum speed at 11,000 feet 237 miles an hour.
The Grumman fighter has a 650 horse-power engine and is said to be able to cruise at a speed closely approaching 250 miles per hour. This machine is a biplane with the undercarriage retracting so that the wheels move up into recesses in the sides of the front of the fuselage. The wing span is 28 ft. 6 in.
So far as flying boats are concerned Consolidated Aircraft have supplied a number to the U.S. Navy and more have been ordered. The American conception of the Service flying boat differs from the British mainly because of the different methods used for securing water stability. The stub wing float, or short wing rooted to the bottom of the hull and acting when the machine is on the water as a lateral stabilizer, is more popular in the United States than it is in Great Britain. British monoplane flying boats for Service use have the ordinary wing tip float. Where the wing tip float is used in the marine aircraft of the U.S. Navy the float is sometimes retractable. It turns and folds up to form the wing tip when the machine is in the air. This form of retractable wing tip float is an essentially American development and has not been tried in Great Britain.
In the matter of research the Americans are well placed and they have been responsible for several noteworthy advances in the performance of military aircraft. Perhaps the most interesting of the more recent researches is that into sub-stratosphere flying.
The United States Army Air Corps bought from the Lockheed Aircraft Corporation a twin-engined monoplane resembling the Lockheed commercial type but fitted expressly for experiments in high flying. The machine has a sealed cabin within which pressure may be maintained by appropriate pumps and it is designed to give a high performance at a great height.
In Great Britain sub-stratosphere flying has been done with the pressure suit; but many authorities are of the opinion that the pressure suit, which the pilot wears like a diving suit, is unpractical and that Service high flying in the future will all be done with pressure cabins. In this form of experiment the Americans have taken the lead.
CONSOLIDATED FLYING BOATS of the PBY-I type are extensively used in the United States naval air service. These aircraft are fitted with retractable wing-tip floats to provide stability to the aircraft when it is on the water. The supports for the wing-tip floats fit into slots in the wings when the floats are retracted; the floats form the tips of the wings.
When the position of the United States air forces is considered generally, it is again evident that its strength is based to a larger extent than in any other country upon commercial flying. It is the production of commercial machines that has enabled the American designers and constructors to make such rapid and notable advances in performance and in methods of construction.
Moreover, it is the commercial work that has caused efficient production systems to be evolved. The United States aircraft industry is not swollen with huge military orders, but is firmly founded on commercial orders. Military orders are now being given it in increasing quantity, but the foundations remain commercial.
It is obvious that this sound commercial basis is a source of strength to the entire United States air forces. The spur of commercial competition has encouraged the use of stressed skin all-metal construction and the introduction of numerous components of the highest importance, such as retractable undercarriages and variable pitch feathering airscrews. Such an incentive is perhaps more effective than any artificial spur which can be applied solely for military purposes in time of peace. About the middle of 1938 a mission was sent to America by the British Air Ministry to examine the possibilities of buying military machines from the United States for the purpose of helping forward the Royal Air Force expansion programme. Orders were eventually placed for 400 American military machines. There is, therefore, a link between the British and the United States sources of aircraft supply.
Methods of training have also been parallel in some ways. The Link trainer for teaching pilots the technique of instrument flying while on the ground is an instance of the kind of training method adopted by both countries.
The personnel of the American services is about on a level with the personnel in the air forces of the leading European Powers such as Great Britain, France, Italy and Germany. American mechanics are noted for their skill, and America probably knows as much about organizing maintenance of machinery of whatever kind as any other country in the world.
The basing of American prosperity upon such factors as large-scale motorcar production has, in many ways, especially fitted the United States for the efficient production, maintenance and handling of aircraft whether for civil or military use. Without doubt the American air forces, naval and military, are at the present moment among the strongest in the world.
The naval side is especially powerful, both numerically and from the quality point of view. In any race in aerial armaments America has a great advantage in her understanding and experience of the methods of large-scale production.
Her efficiency has been demonstrated during air exercises similar to those which are held from time to time by the Royal Air Force; also by formation flights which have tested the mobility of her flying services no less than the skill of the crews and the soundness of the equipment.
Recent flights along the Pacific coast were of this kind. Forty Consolidated PBY patrol machines of the U.S. Navy, carrying some eighty officers and 200 men, flew from San Diego (California) to Seattle (Washington) and, later, flew back again. The flight was a routine journey. This is a good example of the kind of work done by the American service. Such work corresponds to that of the British long-range formation flights.
It was the American Army Air Service, under General William Mitchell, that undertook, from the summer of 1921, the classic series of bombing tests against surrendered German warships. These tests have been quoted again and again, ever since, by those who are discussing the relative defensive and offensive powers of warship and aeroplane. No such comprehensive trials have ever been done since by any other national air service.
AN AMERICAN ARMY SUB-STRATOSPHERE AEROPLANE supplied by the Lockheed Aircraft Corporation for experiments in high flying. The aircraft is similar to Lockheed commercial types, but is specially fitted with test apparatus. The pressure is maintained within the sealed cabin by air pumps, and the supercharged engines are designed to give the aircraft a high performance at altitudes over 20,000 feet.