AERIAL NAVIGATION.

Timaru Herald, Volume XIC, Issue 13393, 17 September 1907, Page 7

AERIAL NAVIGATION.

BALLOONS WILL NOT DO. Discussing the problem of atrial navigation fifteen years ago, Sir Hiram Maxim said lie did iic.t think that any great success _could bs attained by moans of balloons. "Any object, to float in air after -J,., manner of a balloon, must have a, mean .specific gravity less than the air itself, ami this dots not admit of sufficient solidity to enable it to ba propelled through the air at a speed great- enough to ba of any practical use as far as aotual aerial navigat ion is concerned." To drive a balloon through the air at 15 miles an hour, lie says, "would give an atmospheric pressure against it of lglb ]x.*v square foot, which would firet distort and then destroy it." Balloons have been made cylindrical, ' cigar-shaped, and fell-shaped; their construction and lightness have been all that could b? desired. Nevertheless it has Ix'fn found that, with all the power that it is possible for them to carry, they still float helplessly with the wind; it would therefore'appear that if the air is ctit to be f.ucceissfully navigatedi we miut- search for some other means. However, there is still a large number of the unscientific who look for the solution of this problem through the agency of balloons.

. Many experimenters and writers liavc imagined that a successful flying machino would have to bs propelled by wings, after the manner of, a bird, but the wings, tail, and body of a bird act to some extent as an aeroplane, and the same instruments are used both for propulsion and support. But it is neither necessary nor practical to imitate the bird too closely, because screw propellers have been found to be very efficient, and may be connected dircetly with any motor without intervention of the numerous articulated levers which are necessary to imitate the complicated movements of a bird's wings. If a machine for navigating the air is ever to bo of any practical value it must move through the air at a speed at least equal to tha.t_ of the wind. Supposing that- the machine should travel through the air at" the rate of 40 miles an hour; at i this speed there would bs no necessity of a balloon, because, if only a a small"part of the material which formed the covering of the balloon should be stretched on a light frame in the form of a kite, and should the. plane of this kite he tilted a few degrees above the horizontal, it would be found that the atmospheric pressure on the under side of theV plane 'would suSficiently exceed the pressure on tho upper side to lift quite as much as a balloon would lift. Moreover, it has been found that a thin, flat plane travels very easily through the air. Therefore with an aeroplane; which would travel at the rate of 40 miles through the air, we should have the. buoyancy of the balloon with loss than half the materials and withy nothing to prevent tho apparatus from being rapidly shot through the air. From, this I think we shall seek to navigate the air with machines heavier than the air.

Prof. Langley and myself were bath independently engaged at the same time on similar experiments, with a view of finding out how much power was required for llight. The professor attached his machinos to a rotating arm mounted on a central pivot, the arm being 30 feet long. In iny experiments I employed an arm rather more than 31 feet long, the Radius of a 200-foot circle. We were both provided with very delicate and accurate apparatus for measuring how much power was required to drive a plane through Ihe air, how much the plane would lift at various angles and at- various speeds, the efficiency of screw propelleis. etc., and we both arrived at practically the same result*, l'rofexsor Langley found that an aeroplane would carry 2501b to the horse power. T'lie maximum load ever carried was at the rat-e of 2501b to the horse power. In my experiments I found that the aeroplane always worked well when the speed was- greater than 30 miles an hour, and that the most- favourable speeds were in the vicinity of 60 r.iilti; per hour. Most of my experiments were tried with aeroplanes tilled in such a. manner that their inclination was 1 in 1-1; in other word.", when my planes advanced 14 inches !!• y pushed the air down 1 inch, and at thiis angle I lifted as much as 81b per supeilieial foot. T found also that my planes when placed at tls is an gle would carry 14ib for every pound of push imparted to them by the screw propeller. Also that an inclination as ;;ma]l as 1 in 2) would give sufficient supporting power to a flying machine, and at this inclinajiion the plane would carry 203b for evenpound of push received from the screw. Kxperimenls prove that a screw is a, fairly -economical propeller to use in the atmosphere. If a thin pine board 20 ftxilong and 2 feet wide, with tlie edges 'well sharpened, the bottom side being slightly concave and the top side slightly convex, be srsprnd-.-d in the air with ilie front i-dgi- 1 ineh higher than the back eilgi-, and li ■ driven through ill" air with a two-

hlacloil »(MiiU-ii imijii-IUT 28 inehe.i it; diameter at the rale of 50 miks ail hour. we -!ii.n!d (ind tlint it would carry approximately a load of 21011) —including its own weight sintl llh' weight- of tin' jiytyelkv—ur tlie Weight < 1 iar could Ifc lifted by a moderate >iz mI 1i dloon; ami the power uii'i'd would In 1 1.33 horse power, t<> which would have to be added 20 -pt-r cent fov the- slip of the hevew. The screw and tlie board lolleetively need not weigh over 12ib. As to motor. Sir Hiram at that time'believed that this ira'.ri In- a, stoam online, lmt the pel nil motor has been inmien-elv improved ::ince then.