Flight, February 1930
AN INTERESTING AMERICAN AMPHIBIAN
The Towle All-Metal T-2
GREAT minds think alike, we are told, and often one comes across some new idea which has occurred simultaneously to two individuals widely separated, one being totally unaware
that another has been working on almost identical lines. Such a case has occurred quite recently in England and in the United States. For some time now Saunders-Roe of Cowes have been working on an amphibian version of their little "Cutty Sark" flying boat with two "Hermes" engines, and the machine has now been finished and flown in its amphibian form. It recently paid an unpremeditated visit to Lympne aerodrome, and later returned to its home at Cowes, thus making use of both its forms of undercarriage. Towards the end of last week we received from the United States the accompanying photographs and brief particulars of an amphibian recently produced by the Towle Aircraft Co., Inc., of Detroit, Michigan, and known as the Towle T-2. This machine shows how an American and a British designer have thought along almost identical lines.
The amphibian type of aircraft is one which is very urgently needed, but it is also one which is not easy of achievement without the sacrifice of a not inconsiderable amount of paying load. In a rough and ready way, one may probably assume that the weight of the amphibian gear, or more concisely the land undercarriage portion, will be for many types equivalent to one paying passenger, while in large machines it may amount to a good deal more.
In the Towle T-2 the designer has evidently said to himself: "we must have outboard floats in any case for lateral stability on the water. Why not make use of them, and their supports to carry the wheels of the land undercarriage?" Much the same ideas must have been running through the mind of Mr. Knowler when he got out the amphibian gear of the "Cutty Sark."
Making use of the outboard floats as supports for and streamline fairings of the wheels brings with it two problems: The floats must be set deep in relation to the main hull in order that the wheels, when lowered, may project sufficiently to keep the keel of the main hull above the ground. And the landing stresses must be taken on the wings when the machine is being operated from the land. Both mean an increase in weight. On the other hand, if the wheels are made to retract into the floats, no extra drag is added, and so the performance of the machine is not adversely affected. And this is what has been done in the case of the Towle T-2. Unfortunately, the Towle Aircraft Co. has not sent us figures for the tare weight of the machine, and so it is difficult to form an idea of the increase in structure weight which the amphibian feature has introduced. The photograph of the cabin indicates that there is seating accommodation for six people, including the pilot, and as the engines develop together 330 h.p., the power expenditure per occupant is only 55 h.p., which does not impress one as being unduly high, especially for a machine with a top speed of 135 m.p.h. On the other hand, the wing loading would be considered somewhat on the high side in a British machine, being no less than 15-15 lb./sq. ft. The power loading is, however, not excessive, being but 13-4 lb./h.p. and the combined loading is not unusual, the "wing power" being 1-13 h.p./sq. ft. The Everling "high-speed figure" is high for a machine of this type, i.e., 14-8, indicating that the minimum drag is low, in spite of the fact that radial engines are fitted.
Of the structural details nothing is known but what may be gleaned from an examination of the photographs. This indicates that the cantilever wings are of a form of all-metal construction somewhat similar to the Junkers. At any rate, a corrugated covering is used, although it is not certain that the Junkers' multi-spar construction has been followed.
The boat hull is planked with smooth metal plates, and shows a Vee-shaped planing surface, however, without the "ledge" found on the Saunders-Roe "Cutty Sark," and without the hollow flares as found on many other British flying boats. With its comparatively narrow beam, and the absence of any means for turning the spray down, one would expect the machine to be somewhat "dirty" on the water and to send considerable quantities of spray on to the propellers. We are unaware whether or not this is the case.
The mounting of the land undercarriage in the outboard floats and their supporting "trousers" incorporates hydraulic operation for retracting the wheels. When the wheels are raised, spring-loaded flaps close the apertures, leaving the float bottoms smooth.
The cabin accommodation can to some extent be seen in the photograph. And the front view appears to indicate that there is a door in the starboard side of the hull, aft of the wings, by which the emplaning and disemplaning of passengers from a motor boat or dinghy should be a fairly simple operation, as the passengers are not asked to clamber about all over the machine in order to get on board.
The two Wright engines are neatly mounted on top of the wing, on streamlined supports, and well cowled. One assumes that the petrol is carried in the wing, and that, therefore, pump feed must be employed.
One objection to machines of this type is that the propellers are not only subject to a good deal of spray, but that they, and the engines, are close to the forward part of the cabin. If pusher engines could be fitted (and persuaded to cool properly) not only would the noise reaching the occupants be reduced, but the propellers would be removed from the forward portion, and passengers could enter in comfort through a forward door, and could also wave their hands and/or handkerchiefs through the windows without fear of having their nails manicured by the propellers. If such an arrangement is possible from engine considerations, it seems to us that an almost ideal amphibian is produced.
THE TOWLE AMPHIBIAN: Three views of a new American amphibian flying-boat constructed by the Towle Marine Aircraft Engineering Co., of Detroit. It has a metal hull and accommodates four passengers. The wing span is 52 ft.; the overall length 33 ft.,and the weight, empty, 2,750 lbs., and fully laden. 4,420 lbs. Powered with two 150 h.p. "Comet" (Aircraft Engine Co.) engines, it has a speed range of 45-115 m.p.h.
THE TOWLE T-2 AMPHIBIAN: Front view of the machine on the slipway. The wheels are retracted into the outboard floats.
THE TOWLE T-2 AMPHIBIAN: In this rear view the machine is seen resting on its wheels which protrude through the bottom of the floats.
DIESEL-ENGINED: A Towle flying boat powered by two Packard Diesel engines of 225 b.h.p. each. The machine has a tare weight of 3,400 lift, and with a load consisting of 10 gallons of lubricating oil, 90 gallons of fuel oil for six hours, and 10 people at 170 lb. each, has a gross weight of 5,805 lb. The maximum level speed is 125 m.p.h., the cruising speed 100 m.p.h., and the'sea level rate of climb 650 feet per minute.
View looking forward inside the cabin of the Towle T-2 Amphibian. Note the generous proportions of windows and windscreen.