CAB38-23 — Page 146

Page 146

Page 146

2

If an airship keeps at a height of 3,000 feet, the particular vessel she is trying to attack with bombs cannot fire at her within a certain distance, say 6,000 yards, but another vessel stationed 6,000 yards from the first can keep her under fire the whole time.

The Ordnance Board should be directed to prepare tables showing the corrections to the elevations shown in the range tables which should be made when firing at objects at heights up to 3,000 feet above the gun.

These should be calculated theoretically and if necessary, tested by firing at a target composed of a very light net in the form of a cross supported by a captive balloon in calm weather.

The two factors on which the correction will depend, namely, the direction of the force of gravity with reference to the line of sight, and the tenuity of the air at the greater height tend to counteract each other, so that the correction will probably be found to be very small.

Aeroplanes present too small a target to have much chance of being injured by gun fire except at very short range, so the problem of defence against them is much more difficult.

Aeroplanes as a defence against Airships.

Although guns can be used by ships as a protection against attack by airships in the open sea, they cannot be used generally to defend magazines and stores on shore in a populous country on account of the danger from falling projectiles.

In that case and in all cases when they are available, attack by aeroplanes will form much the best means of defence.

An aeroplane is, or at all events can be, very much faster than any airship, and although if the weights carried by an airship are reduced in proportion to the height she intends to reach, she can ascend to that height much quicker than an aeroplane, the aeroplane can go higher, and when once above her level, having higher speed and turning in a smaller circle, she can close and fly along the top of the airship as close as she likes.

The only risk to the aeroplane would be from rifle fire, from which she would be to a great extent protected by the body of the airship itself.

The best way of destroying the airship would probably be by means of a squib specially designed to ignite the hydrogen and fired from a pistol at close range.

The Royal Laboratory could no doubt design such a squib.

Eastchurch is very well situated as a station for aeroplanes for the defence of Chatham or Chattenden Magazine from airships, as they ought to get notice of the approach of airships from the coast or Thames estuary in time to rise and intercept them.

Use of Airships for Scouting.

It has been suggested that airships of large size can accomplish the work of several cruisers in scouting, owing to the extended view they obtain from high altitudes, but against this it must be remembered that airships when out of sight of land very soon lose their reckoning, and, even if working in conjunction with a cruiser, they would be very likely to lose her altogether if they once got out of sight. In the North Sea it is doubtful if a much more extended view would often be obtained from the airship than from the cruiser, as the atmosphere is rarely sufficiently clear, and the use of a telescope in the airship would be more difficult.

As this advantage is very frequently claimed, it would be advisable to call for reports from vessels cruising in the North Sea as to the distances at which vessels are lost sight of on each day that they are at sea for a considerable period.

If the state of the atmosphere is such that vessels are lost sight of before they are hull down from the bridge, it is not likely that they would be visible much further from an airship.

Action on the Enemy's Coast.

The most pressing aerial requirement for the Navy at the present time is the provision of means for using aircraft on the enemy's coast.

Aircraft are absolutely essential for ascertaining the disposition of the ships inside the eneiny's ports, to find out in the morning whether any vessels have left the port or arrived during the night, what ships pass through the Kiel canal, and many other

purposes.

Page 146

Page 146