Popular Science Monthly 



Vol. 89 

 No. 3 



239 Fourth Ave., New York 



September, 1916 



$1.50 

 Annually 



Torpedoing a Submarine from an 



Aeroplane 



BECAUSE an airman flying above the 

 water can sight an underwater craft 

 and detect its approximate depth 

 with the naked eye, inventors ha\e de- 

 vised a number of bomb-dropping con- 

 trivances in an endeavor to make the 

 most of this strategic advantage and 

 place the submarine at the mercy of the 

 aeroplane. One of the most recent of 

 these devices is an aerial torpedo or 

 bomb containing high explosive which 

 when dropped from the aeroplane makes 

 a rapid and straight descent Ijeneath the 

 water and explodes at the proper depth 

 and [)roximity to wreck a sulimarine. 



The bomb consists of a shell filled 

 with high explosive and into its closed 

 end is fixed a detonator which consists 

 of a tube containing a layer of metallic 

 sodium, a layer of gun cotton and a 

 layer of ordinary fulminate. Attached 

 to the shell is a parachute, which is 

 nothing but a dished circular plate. 

 This acts as a guide in the descent of the 

 bomb from the aeroplane to the water 

 and also regulates the speed of the bomb 

 once it is under water, allowing it to 

 sink slowly. 



The cover of the bomb as well as the 

 cap of the detonator-tube are perforated. 

 When the bomb has sunk to a certain 

 distance, water flowing in through these 

 perforations ignites the sodium (a prop- 

 erty of sodium), which fires the gun 

 cotton, which discharges the fulminate, 

 which sets otT the bomb. These different 

 stages leading up to the actual explosion 

 occur nearly simultaneously, but should 

 they fail — that is, should the unforeseen 

 happen and the sodium not ignite, an 

 electrical igniting mechanism is provided 

 which will discharge the fulminate. 



\Miliin the shell there is a dry battery 

 connected to a contact point and to one 

 entl of a platinum glow wire embedded 

 in the fulminate. The other end of the 

 glow wire is connected to an insulating 

 lever carrying a contact point. This 

 lever member is a closed hollow tube 

 containing a little mercury, which, flow- 

 ing to the lower end, tends to keep the 

 lever down. A tube in the perforated 

 cover contains a bucket filled with a dry 

 sponge. 



When once the bomb has struck the 

 water and the sponge has sufficiently 

 absorbed it, its weight bearing on the 

 end of the lever member raises this lever 

 into contact with the terminal, thus 

 completing the circuit and discharging 

 the fulminate. 



There are sexeral very obvious objec- 

 tions to a bomb of the type described. 

 It is ver\- difficult to hit an object on 

 the ground when the aeroplane is very 

 high. Indeed, no satisfactory' instru- 

 ment has thus far been invented to drop 

 bombs from great heights with anything 

 like the precision that marks the firing 

 of projectiles from great guns. If the 

 aeroplane is to destroy a submarine in 

 the manner proposed, the bomb-dropper 

 must be very near its target — so near 

 that it would itself be in danger from 

 gun fire. 



Some of the difficulties of dropping 

 bombs accurately spring from the fact 

 that an aeroplane moves through the 

 air at a rate of at least forty-five miles an 

 hour. Allowance must be made not 

 only for that forward movement, but 

 also tor the movement r)f the submarine 

 as well as for the wind. A hit would 

 therefore be almost a matter of luck. 



S'iS 



