when these engines are produced we shall reduce our maintenance costs by about 75 per cent.

The cost of fuel is a very big item, but already we are well within reach of using heavy oil instead of petrol without any appreciable increase of weight. For a journey of four or five hours, when this is obtained, we shall at once save something like 70-80 per cent. on our fuel bills.

Insurance.-Insurance is partly affected by the volume of traffic, partly by technical considerations. I have already indicated that we must be patient regarding the traffic and Government must help during the time our custom is built up. An increase of traffic will increase the business of the insurance underwriters, who will at once lower their premiums. From the technical point of view, premiums are high to-day chiefly on account of the danger of an engine failure and consequent damage to the aircraft. They are not high for the insurance of goods, passengers, or crews, because the insurance underwriters realise that the risk there is actually very small. It is the expense of repairing aircraft against which they have to insure. With a perfectly reliable engine, which I believe must come, insurance rates will certainly drop, and I can see no reason why they should not be reduced at least 50 per cent. in the quite near future. In fact, to-day, already, in the case of one company which has been particularly free from breakages, this reduction has actually come about. Insurance companies are not afraid to cover death risks. It is insurance against these tiresome little breakages and so on that are so troublesome, and we have got over that.

These three big items in an estimate which I have here of the expenses of a company running several services, amount to £131,000 out of a total annual expenditure of £264,000. By means of the steps in progress I have just enumerated, this item of £131,000 can be reduced to £35,000, and our total of £264,000 annually expended drops at once to £168,000, a reduction of 36 per cent.

There are other technical items which will save money in maintenance, such as metal propellers, all metal construction, &c., &c. Again, there are other items of technical development which will not reduce the costs of running the service, but will increase our carrying capacity per horse power. First, metal construction is promising very well indeed, and it appears almost certain that considerable weight will be saved by all-steel construction as compared to the present wood conI believe there have been planes designed and approved already which show an actual saving of 20 per cent. in structural weight. I am not a scientific expert, but I believe that, if 20 per cent. is saved on the structural weight of an acroplane, that aeroplane will at once have an increase of about 7 per cent. to its paying load for the same horse power. Secondly, it is uneconomical to use exactly the same engine and propeller to get off the ground as for flying at cruising speed. The limiting factor in the carrying capacity of any aircraft to-day is the amount of weight which can be lifted safely from the ground with the engine all out; once the machine is well up in the air, the engine is throttled back and this load is carried quite easily; in fact, a considerably greater load could be carried if it were not for the difficulty of getting off. Experiments are now in progress towards obtaining a variable pitch propeller or a two-gear engine by which a considerably increased weight could be lifted off the ground with the same horse power. Again, slotted wings and variable cambered

wings are being devised by which greater lift can be obtained when getting off and landing, which again means a greater load can be lifted from the ground for the same horse power.

Assuming that some of these experiments are successful, I see no reason why the useful load of an aeroplane of given horse power should not be increased by about 20 per cent. of what it is to-day without any increase of horse power. So once more I repeat the statement that I made originally: I believe that in a very few years we shall be carrying ten passengers, or their equivalent weight, at 100 m.p.h. for about 28. a mile, which surely is a commercial proposition; that is, about 24d. per passenger per mile. I think that is enough of the financial side of air transport.

Comfort is being improved. We shall have comparative silence before very long. Experiments are in progress in heating and ventilating the cabins, of which we know little at present. I hope this may tend to eliminate air sickness, the exact causes of which are still unknown. Personally I contend that the air is the most comfortable means of transport to-day for those who like it; in five years' time I think no one will be able to deny its superiority.

As soon as its reliability is established all mails will inevitably be transported by air, and the pounds of letters carried to-day will be converted into tons. These are only the possibilities of to-morrow.

I will not waste your time by wandering into the wonderful realms of the more distant future.

I will only say that heights of 30,000 feet and speeds of 300 miles an hour are possible, placing New York within 12 hours of London; that navigation through any cloud or storm will be as easy to the aircraft of the future as navigation of the sea is to the big ship of today and to the sceptical I only say, "Compare the latest commercial air liner of to-day with the 50-h.p. box kite of 1912—and think."’

Now, even though air transport could never become a commercial proposition, no one could deny its enormous value to the British Empire. I heard Commander Burney, who is going to read a paper after me, put the case for air transport very clearly the other night. He pointed out that the most prosperous country in the world to-day was America, because she was self-contained; almost the whole of her trade was carried on within her own frontiers. He pointed out how this was easily possible in America because of the quick communication provided by their excellent railway system between the various business centres. He drew the lesson that, in order to prosper, Great Britain must also arrange that the greater part of her trade is carried on within the Empire and that she must no longer depend on the European markets. The British Empire is just as self-contained as the U.S.A. in its ability to provide all it wants from its own territories. The reason that this had not been accomplished was to some extent the slowness of our communications with our overseas Dominions. If these communications could be quickened up-for example, a daily mail to India in 72 hours and a daily mail to Australia, taking perhaps a week, or less, could be instituted-it would at once become possible to increase the internal trade of the British Empire, and so by degrees make the Empire much more self-supporting and independent of the rest of the world with its changing conditions and fluctuating currencies. I cannot put a better case than that for the institution of air transSir Sefton Brancker

port as a means of linking us up with our overseas Dominions, and this could be done before air transport was actually in a position to pay its way.

Here again we meet the necessity of educating the public. We are ruled by the voice of the majority, and no Government will face the responsibility of spending large sums on an enterprise like air transport unless it has the people behind it--and so we must leave no stone unturned to teach the public what aviation means to this country, and so get them to say that they must have it cost what it may. When air transport does pay its way, as it assuredly will, the air services will grow and multiply, and we will automatically create a great national reserve of aerial resources of designers, progressing continuously towards greater efficiency-of factories prospering and well manned with skilled workmen of mechanics, wireless operators, meteorologists and photographers making their careers in connection with aviation; and, above all, of pilots with real air experience-in fact, real airmen.

The CHAIRMAN: I will now ask Commander Burney kindly to read his paper.

THE ESTABLISHMENT OF A SELF-SUPPORTING
AIRSHIP SERVICE.

Commander C. DENNIS BURNEY, C.M.G., M.P.: Mr. Chairman, My Lords and Gentlemen: The establishment of a self-supporting Airship Service necessitates the overcoming of many difficulties of a financial, political, and technical character and, perhaps, the least of these difficulties are those which are technical. Consequently, any analysis of the problem requires the investigation of all three factors. Technical questions are generally more interesting to the majority, but I feel that the cause of aviation will be better assisted in making some suggestions as to how the financial and political difficulties can be overcome; since, until a solution is found to those problems, no progress of any kind can be made on the technical side.

The benefits that would accrue from the successful establishment of an imperial airship service may be divided into three groups :

(i) The imperial and political advantages accruing from a safe and cheap form of transport that would provide for the British Empire the equivalent of the through trunk railways of America in-so-far as mails and passengers are concerned.

(ii) The value in war-time of a fleet of airships together with their fuelling bases all over the world.

(iii) The value of a commercial company with British capita operating a service on a profit-making basis.

PROSPECTS OF COMMERCIAL SUCCESS.

I think it would be better to discuss the third group first, as unless there is a reasonable prospect of a commercial company earning profits, there is a definite bar to that great expanison which is essential for the full realisation of the first two groups.

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I will first briefly describe what has been done in regard to commercial work; then I shall indicate the recent technical developments which allow of a considerably more optimistic estimate being made of the revenue-earning capacity of a commercial company.

When airships were in their early stages, even as long ago as 1910, a German airship company called "Delag" commenced passenger work, with a result that some 26,900 passengers made journeys. After the armistice (in September 1919), this same company, with a ship named the "Bodensee" (speed, 81 m.p.h.), recommenced the passenger service between Berlin, Munich, and Friedrichshaven. In three months this vessel made 103 flights, covered a distance of 50,000 kms. and carried 2,380 passengers and about 30 tons of freight. These statistics seem to indicate the suitability of an airship for passenger work, and this indication is reinforced when one remembers that there is no record of a fatal accident to any passenger carried by a commercial airship.

There are, however, several outstanding defects which have hitherto prevented the airship developing rapidly as a passenger vehicle, and they may be tabulated in the following order :

(a) There was no method of anchoring or mooring the vessel for the purpose of fuelling and of embarking or disembarking passengers and freight.

(b) The carrying capacity was too small in relation to the capital cost of the vessel.

(c) The radius of action was too small for the great ocean

routes.

The developments which took place both during and since the war have, in a very large measure, overcome these defects. Nevertheless, no vessel has yet been built which embodies these developments, and this has been due, almost entirely, to the financial depression.

Take, for instance, the mooring mast, as this is undoubtedly an invention of far-reaching importance. By means of this mast it is now possible for a ship to be fuelled and gassed as well as to receive her passengers and freight without being put into a shed. The conditions precedent to a flight are, therefore, radically altered, as not only are the risks inherent in the berthing of a ship eliminated, but the number of men required for the operation is greatly reduced. Before the invention of the mooring mast it was necessary that the ship should be berthed in calm weather. Naturally, it was impossible for a time-table to be adhered to and, furthermore, not only did this objection militate against a commercial development, but the number of men required was about three hundred-a type of overhead charge quite impossible from a commercial point of view. By means of the mast, however, it is possible to moor a vessel with only six men, and the condition of the weather scarcely enters into the question, as the operation can be carried out in a forty-mile-an-hour wind.

Experiments at Pulham showed that out of a total of 111 days during which the mast was occupied for experiments, flights were possible at any time, and, in fact, some fifty flights together with four night landings were made.

A further development of considerable importance became evident after overhaul and repair of the ship whilst moored to the mast. The experiments carried out included the changing of an engine, a gas Commander Burney.

bag, and a propeller, as well as repairs to the bow structure and the mooring wire.

It is apparent, therefore, that the airship shed can now be considered as a dry-dock and need only be used every few months for large repairs or a general overhaul.

In considering the second clause-the high capital cost of the vessel on the basis of its carrying capacity-the most important factor is the figure that can be given to the percentage of disposable lift. The disposable lift is that proportion of the total displacement of the ship which can be utilised for the support of fuel, passengers, crew, &c. Such lift can be improved in two ways: firstly, by greater efficiency of design, and, secondly, by an increase of size in the vessel built.

The improvement possible on these lines is very strikingly shown by comparing L. 1, L. 33, and L. 71.

The third clause the necessity of the vessel having sufficient endurance for the great ocean routes-is to a great extent governed by the disposable lift factor. Another consideration of almost equal importance is that of engine efficiency and fuel consumption, and in this connection a great advance has recently been made as a result of experiments carried out. Briefly, these experiments have established beyond dispute that kerosene and hydrogen can be used together as an airship fuel. In consequence, the radius of action of a vessel has been increased by 33 per cent. and, furthermore, owing largely to the very high thermal efficiency obtainable with this fuel, the exhaust temperatures are so reduced that the life of an engine should be increased by 400 per cent. The thermal efficiency is really remarkable, as some of the tests have given a figure as high as 38.7 per cent. which, I believe, is the highest efficiency ever obtained so far, the figure for the Diesel engine being, I think, 33 per cent. As regards costs, the reduction takes place in two ways: the fuel is under half the cost of petrol and the amount required is one-third less.

I think the best way to show that these various improvements render a vessel efficient for the great ocean routes will be to give the capabilities of the new 5,000,000 cubic feet vessels which it is proposed to build. Such vessel would be approximately 760 feet in length and 110 feet in diameter at its maximum girth. Allowing a disposable lift of only 50 per cent., so as to make adequate provision for the increased ruggedness of construction desirable for commercial work, and assuming a flight of 3,000 miles as the average length of a commercial flight without refuelling, it would, allowing for contrary winds, give 44.5 tons for the carriage of mails, passengers, &c., at a speed of 80 m.p.h. If 375 lbs. is allowed for each passenger, the capacity of the ship will be 207 passengers and ten tons of mail and other freight.

Estimates have been carefully worked out for a fleet of airships of this type operating on the Indian and Australian routes. The total capital required would be £4,000,000, and details of estimated receipts