The tail in this craft is unique and resembles no other flying machine or animal. The tail surface is made up as a biplane, which is of the general appearance and size of the usual aeroplane. Indeed, this tail of over 500 square feet area is twice as large as the single-seater fighting-aeroplanes used by the army.
Engines
The four Liberty engines which drive the boat are mounted between the wings. At 400 brake horse-power per engine, the maximum power is 1,600 horse-power, or with the full load of 28,000 pounds, 17.5 pounds carried per horse-power. One engine is mounted with a tractor propeller on each side of the centre line, and on the centre line the two remaining engines are mounted in tandem, or one behind the other. The front engine has a tractor propeller, and the rear engine a pusher propeller. This arrangement of engines is novel, and has the advantage of concentrating weights near the centre of the boat so that it can be manœuvred more easily in the air.
Controls
The steering and control in the air are arranged in principle exactly as in a small aeroplane, but it was not an easy problem to arrange that this 14-ton boat could be handled by one man of only normal strength. To insure easy operation, each control surface was carefully balanced in accordance with experiments made in a wind-tunnel on a model of it. The operating cables were run through ball-bearing pulleys, and all avoidable friction eliminated. Finally, the entire craft was so balanced that the centre of gravity of all weights came at the resultant centre of lift of all lifting surfaces, and the tail surfaces so adjusted that the machine would be inherently stable in flight. As a result, the boat will fly herself and will continue on her course without the constant attention of the pilot. However, if he wishes to change course, a slight pressure of his controls is enough to swing the boat promptly. There is provision, however, for an assistant to the pilot to relieve him in rough air if he becomes fatigued, or wishes to leave his post to move about the boat.
In the design of the metal fittings to reduce the amount of metal needed a special alloy steel of 150,000 pounds per square inch tensile strength was used. To increase bearing areas, bolts and pins are made of large diameter but hollow.
A feature that is new in this boat is the use of welded aluminum tanks for gasoline. There are nine 200-gallon tanks made of sheet aluminum with welded seams. Each tank weighs but 70 pounds, or .35 pounds per gallon of contents, about one-half the weight of the usual sheet-steel or copper tank.
Loaded, the machine weighs 28,000 pounds, and when empty, but including radiator, water, and fixed instruments and equipment, 15,874 pounds. The useful load available for crew, supplies, and fuel is, therefore, 12,126 pounds. This useful load may be put into fuel, freight, etc., in any proportion desired. For an endurance flight there would be a crew of 5 men (850 pounds), radio and radiotelephone (220 pounds), food and water, signal-lights, spare parts, and miscellaneous equipment (524 pounds), oil (750 pounds), gasoline, 9,650 pounds. This should suffice for a flight of 1,400 sea miles. The radio outfit is of sufficient power to communicate with ships 200 miles away. The radiotelephone would be used to talk to other planes in the formation or within 25 miles.
The principal dimensions and characteristics of the NC type may be summarized as follows:
| Engines | 4 Liberty |
| Power | 1,600 |
| Wing span | 126 upper—94 feet lower |
| Length | 68 feet 5½ inches |
| Height | 24 feet 5⅛ inches |
| Weight, empty | 15,874 lbs. |
| Weight, loaded | 28,000 lbs. |
| Useful load | 12,126 lbs. |
| Gravity-tank | 91 gals. capacity |
| Fuel-tanks | 1,800 gals. capacity |
| Oil-tanks | 160 gals. capacity |