phases of its problems. The committee employs a directing engineer and a supporting staff in Washington, also a corresponding observer of aviation in Europe. The Committee operates a research laboratory at Langley Field, Va., where several hundred able, enthusiastic engineers in the prime of active life continually investigate the problems which make for improving aviation. Every year, in May, meetings are arranged at the laboratories. Interested representatives of Government, the military and civil services, and the industry are invited. These meetings are so highly regarded that two whole days are now required and despite rigid selection of invitations, more than 600 representatives are present. Representatives of the industry value the opportunity so highly that they come every year at large expense from distant cities.

Foreign visitors also seek to visit the laboratories in great numbers, but have to be entertained with some reserve. It is admitted by both foreign and domestic experts that up to the present time the rapid progress of the art of aviation as to speed, size, safety, and range of action is principally due to the fundamental researches of the N. A. C. A. So keenly is this appreciated abroad that in all principal countries large sums are now being expended for research laboratories in which the best facilities of the N. A. C. A. are copied, or, if possible, improved upon. These strenuous research activities in foreign lands throw upon this Government the responsibility of keeping its fundamental research program in avitation at such efficiency that we may not fall behind other great nations in capacity for defense.

These considerations lead the committee this year to ask for a considerable increase of appropriation, which will be explained in detail by Dr. Lewis, but which in short consists of additional staff, materials, supplies, and electric power to operate the newer research instruments, to the amount of $69,150; an experimental airplane costing $50,000; and the sum of $200,000 for the beginning of a new wind tunnel of special design capable of tests up to high Reynolds numbers of individual parts of the large wings of modern airplanes of great wing spread.

I would like to remind you, Mr. Chairman, that the success of the N. A. C. A. depends on its present and past independence of any executive department. Its members, coming as they do from all the sources interested in aviation, both Government and private, meet on equal terms, always harmoniously, and serve the whole field of aviation with fundamental information. If the N. A. C. A. were assigned to some single branch of the Government it would be very unlikely that such harmony and impartiality of purpose, and such a wide basis of expert support freely given could long continue.

With these general remarks made, Mr. Chairman, I would like to ask that you hear Dr. Lewis, the Director of Aeronautical Research, and address questions to him, for he is, I believe, the best informed man in the world in this field.

Mr. WOODRUM. Thank you for your statement, and let me say that we concur in your estimate of Dr. Lewis. We shall be very glad to hear from him.

Dг. ABBOT. In any way I can assist you, I shall be glad to do so. I hope it will be possible for me to get away within an hour, Mr. Chairman.

Mr. WOODRUM. Whenever it suits your convenience, Doctor, we will excuse you.

33819-37-35

IMPORTANT PROBLEMS BEFORE THE NATIONAL ADVISORY

COMMITTEE

Dr. Lewis, are you going to give us a statement of what you are doing, of what you contemplate doing for the next year?

Dr. LEWIS. I shall be very glad to make a brief statement outlining some of the more important problems before the committee.

I will have to apologize, Judge, for saying each year that the demands upon the committee for information are increasing. They are increasing because aviation as an engineering science is probably the most important factor in every important country in the world in developing national defense and extending commercial influence.

Last year I reported about the great advances which have taken place in foreign countries, in Europe especially, in fundamental research. They all appreciate the fact that if they are going to lead in this important field, they have to have sound facts on which to base their designs.

The problems at the committee's laboratory can be divided into three classes. The first of these covers the problems that are of a secret nature, the cases in which the Army or the Navy asks the committee to undertake an investigation that is of such a nature that the information cannot be released to anybody, except to the organization concerned. It usually relates to the design of some new airplane that has particular qualities, that is in advance of anything that now exists.

The second class covers the problems that are incident to immediate design, and these are very important, especially when you realize that the Government spends each year on the Army and Navy over $80,000,000 for new aircraft. If the design of these aircraft is not such that they have superior performance, the $80,000,000 is not well spent. In other words, new aircraft that do not have superior performance, or at least performance equal to that of aircraft already in existence, are almost a total loss.

The third type of problem is what might be called the long-range problem. We have under the main committee, as has been explained by Dr. Abbott, several subcommittees. One of these is the subcommittee on aerodynamics. There are investigations that will result in improving the safety and the efficiency of aircraft and these problems are considered by the aerodynamics subcommittee.

On that committee we have the best men in the Army and Navy, technically speaking; and representatives of the Bureau of Air Commerce, the Bureau of Standards, and other Government organizations, who survey the field, and consider what lines can be pursued to make the airplane more efficient, more safe. It may take perhaps 2 or 3 years to carry a problem through.

The same procedure is followed with reference to engines, with reference to materials, and with reference to structures.

One important problem at the present time is the problem of structures, because if airplanes are going to become larger, it will be necessary to make the structure lighter in proportion to its size.

SEAPLANES FOR TRANSOCEANIC TRAVEL

I would like to speak at the present time with reference to seaplanes. You probably have all noted the report of the Maritime Commission, and to bring to your mind the importance of the seaplane, I have reproduced one of the charts in the Maritime Commission's report.

This chart [exhibiting chart] shows the cost in dollars of carrying a passenger across the Atlantic. Here [indicating on chart] we have dollars on the upper line, and here [indicating] we have the various methods of transportation.

Here is a 40-passenger, 50-ton seaplane, which can be built at the present time. The cost, you will note, is something of the order of about $73, to carry a passenger across, taking care of depreciation, the cost of fuel, and the cost of the crew.

Now, let us look at an airship of the Hindenburg type. There the depreciation is higher because the cost of the unit is much higher. Mr. WOODRUM. What was that?

Dr. LEWIS. The airship itself would cost probably $8,000,000. This seaplane here [indicating on chart] would probably cost of the order of $900,000 or $1,000,000.

Now the cost, you will note, here, runs up to about $132.

Now, let us take the Normandie, on up-to-date ocean liner. There the cost, you will note, is of the order of $67.

Now, let us take the next step, increasing the seaplane from a 40-passenger seaplane to a 150-passenger seaplane weighing 125 tons. You will note that the cost of carrying a passenger across the Atlantic has dropped from $73 down to about $37. And you will note that that cost is much less than the cost of carrying a passenger with a superairship, and less than the present type of luxury liner.

Mr. WOODRUM. Will you put that in some form so that it can be incorporated in the record?

Dr. LEWIS. I shall, Mr. Chairman.

Comparison of major items of estimated operating cost per passenger crossing— transatlantic-at capacity load and 100 percent operation

From report of United States Maritime Commission, November 13, 1937.

The information is analyzed further in the Maritime Commission's report and indicates that with less expenditure, you can have a daily

service each way with a fleet of six large seaplanes in operation across the Atlantic, the crossing being made in 1 day.

The report indicates that the Maritime Commission is very much impressed with the seaplane as a means of capturing the trans-Atlantic trade, rather than spending money on luxury liners.

Mr. WOODRUM. What is the relative cost?

Dr. LEWIS. That would be very difficult to say.

Mr. WOODRUM. Of course, you have it broken down per passenger, which answers it in a way. But, for instance, how much did the Normandie cost?

Dr. LEWIS. I would say the Normandie cost $40,000,000, or something like that.

You probably have noticed in this morning's paper that PanAmerican Airways are asking bids for some six 100-passenger ocean planes, which is the first intimation in the press of the effect of the report of the Maritime Commission.

I mention these facts because we are now confronted with some very important problems in connection with seaplanes.

We have here a model of a modern commercial transport seaplane. This [indicating] is the China Clipper, a type that has now flown about a million miles, going back and forth from San Francisco to the Philippine Islands.

Mr. VICTORY. Without an accident?

Dr. LEWIS. Yes; without an accident.

Mr. WOODRUM. Does that carry only eight passengers?

Dr. LEWIS. It depends upon the run. It only carries eight passengers from San Francisco to Hawaii.

Mr. FITZPATRICK. What is the number in the crew?

Dr. LEWIS. The crew on that flight number four at the present time. That is due to the fact that they have to carry fuel for the 2,200 miles from San Francisco to Hawaii, plus 30-percent extra to take care of any adverse weather conditions.

Now, the next step in size is this seaplane here [indicating on diagram] which is now being constructed. This one will carry 40 passengers. It is being constructed for Pan-American Airways by the Boeing Co. and will weigh 80,000 pounds.

I think you are all familiar with the fact that Pan-American Airways, in cooperation with Imperial Airways of Great Britain, have been operating an experimental service across the North Atlantic during the past summer. They expect to start a regular service next summer with this type of seaplane.

The type of seaplane we are talking about, or the one that I indicated showing the low cost per passenger crossing the Atlantic, as brought out by the Maritime Commission, is this type here [indicating] weighing 125 tons or 250,000 pounds.

There are a large number of problems to be solved with reference to airplanes or seaplanes of this size. You notice here [indicating] that the horsepower is 3,200 for the China Clipper; for the Boeing airplane it is 6,000, and for this 125-ton seaplane it is 12,000.

You will note here [indicating] that we have question marks concerning the lift and drag, because we do not know accurately the aerodynamic characteristics of these large structures. We do know that the larger the airplane or the seaplane becomes, the more efficient it becomes. That is, the maximum lift increases and the minimum drag decreases.

This factor, Reynolds' number [indicating], is not difficult to understand. It is roughly the product of the size of the seaplane that is the distance across the wing-multiplied by the speed of the seaplane. You will note that the Reynolds' number, which is a factor determining the aerodynamic characteristics of the wing, varies for the three models from 30 million to 50 million to 75 million.

NEED OF LARGER WIND TUNNEL FOR MAKING OF TESTS

Nowhere in the world has a test been made in a wind tunnel showing the effect of the air flowing over a wing under those conditions of high Reynolds number, 50 million and 75 million.

We have at Langley Field wind tunnels at the present time in operation that give a Reynolds number of 5 million. To design the new airplane structures efficiently, it is necessary to know just what the lift is going to be and what the drag is going to be.

The drag is a very important factor. A number of years ago, when we had biplanes with struts and wires, and so forth, the drag of the wing in percentage of the total drag of the seaplane or airplane was relatively small, only 35 percent.

Now as the stucture has been cleaned up, the drag of the wing accounts for about 65 percent of the drag of the whole structure and the efficiency is in terms of that drag.

Now, this is lift [indicating on diagram] and this is drag. The ratio between these two characteristics, in this particular case, would be about, say, 14.

Here [indicating] we are guessing at it, and it is about 14. Here [indicating] we are guessing at it again and it is about 21.

Now, what do I mean by 21? I mean for every pound of drag or resistance you obtain a lift of 21 pounds, where here [indicating] for every pound of drag you obtain a lift of only 14 pounds, indicating the efficiency of the airplane.

The problem is this. We do not know the efficiency of this one [indicating] although it is now being built, because tests have never been made under conditions where a seaplane operates at a Reynolds number of 50 million.

I bring this up in particular in connection with the new wind tunnel for which we have asked an initial appropriation of $200,000. This wind tunnel will permit us to carry the Reynolds number up to about 100 million.

Three or four years ago it would have seemed rather foolish to come before this committee and ask for equipment for tests to a Reynolds number of 100 million. But the time has arrived when the information is needed tomorrow. And the country that has that information is the country that is going to lead in military and commercial aviation. In the last analysis, the airplanes that are going to be bought for transoceanic or transcontinental operation are the airplanes that make the most dollars per passenger.

Mr. FITZPATRICK. How long would it take you to construct that wind tunnel, if you are given the money?

Dr. LEWIS. Two years. So that we are over 2 years behind the post now.

Mr. HOUSTON. Is that for the one in the center?

Dr. LEWIS. No; this one here [indicating on diagram].