Vol. II

A Cabinet Officer Needs Educating The authoritative statement of Dr. Work's position in the Reclamation Service case, as set forth in our Washington correspondence this week, indicates that the Secretary of the Interior does not even now fully appreciate the significance of his action in removing an engineer from the head of an engineering bureau and placing there a socalled business man. He is still obsessed with the notion that engineering is merely the "building of dams and the digging of ditches" and that dam building and ditch digging can be carried on just as well under the superior direction of an unsuccessful banker as it can under a successful engineer. When he has had somewhat more experience with the intricacies of government irrigation—or possibly when he has received some instruction through the medium of a congressional investigation-he will know that reclamation is a continuing engineering problem, that requires for its supervision somewhat more than the acquaintance with human nature that presumably is the principal asset of the politician and business man, and which the Secretary assumes to be a non-existent characteristic in an engineer. At any rate he is already learning that what he thought was merely a quiet little political maneuver has assumed proportions that threaten his whole administration.

-Engineering News Record.

And it's up to the engineer to see that the Secretary learns his lesson-learns it so thoroughly that he can recite it

No. 11

backward and pass an examination "summa cum laude".

First Aid to Authors

Un

The Western Society of Engineers, Chicago, is a live organization. In connection with its various activities it has issued a booklet entitled "Suggestions to Authors of Papers", which is full of good advice and many valuable suggestions. Which gives the editor to think. doubtedly many of our members have stored up in their systems material for papers suitable for presentation before the Societies, or for publication in the Journal. Perhaps they are hesitant about presenting the matter because of lack of confidence in their ability as writers. The Chicago booklet will help. The Secretary will be glad to obtain copies for budding authors.

A Friend Passes On

In the death of Charles Cunliff, Jr., the Engineers' Club and Associated Engineering Societies lose one of the most active of their younger members.

We regret profoundly the passing of our older associates but we are consoled in some measure by the thought of their achievements. When the younger men leave us, their work only begun, our sorrow is accented by the thought of what might have been; of promise unfulfilled.

Charlie Cunliff leaves behind him a record of work well done; of straight living; of unassuming service. We have lost a friend.

The

Engineering plays a most important part in aircraft development. This is particularly true of the airplane wherein stresses are set up as a result of the violent maneuvers through which the airplane passes. It may interest you to know that the first time a dirigible balloon has been designed with complete stress analysis is in the case of the ZR-1. The National Advisory Committee for Aeronautics, which is made up of engineers of the highest class and of international standing, investigated the design of the ZR-1 and made a complete stress analysis of its structure. stresses vary mainly with the square of the speed and are set up principally in the operation of controls. The entire frame work, which is of duraluminum, is called upon to withstand the reaction caused by setting over the rudder or elevators during high speed maneuvering at a low altitude. The members are, at the same time, called upon to take up loads occurring from the expansion of the gas inside the balloonets, which are contained inside the outer envelope. It was the lack of proper engineering that caused the collapse of the R-38 in Eng

*An address given before the Associated Engineering Societies of St. Louis. Sept. 27. 1923.

land. This airship was originally shorter, but it was cut through the center and a considerable length of section inserted. The result of quickly setting over the rudders when going at high speed caused the frame-work to buckle. An explosion occurred and the airship was totally destroyed.

Airplane engineering has advanced from the early stages of thumb-rule methods to a very high standard of comprehensive engineering. Wind tunnels have been built by the National Advisory Committee for Aeronautics, Navy Department, War Department, Bureau of Standards, Curtiss Airplane Company, Massachusetts Institute of Technology and many others where airplane models are subjected to a very rigid test and the forces set up by various elevator and rudder settings are easily determined. These tests are carried still further and practical tests on full-sized machines are conducted. Accelometers and various other measuring devices are used and pressure tubes are inserted in the covering of the parts of the plane subjected to test. In this manner, the air pressure may be taken at any point on the surface of the main planes, stabilizer, rudder or elevator and a plot made which will indicate the distribution of the loads from which may

be readily determined the forces set up. These pressure tubes are connected to manometers which are enclosed in a light tight box, a sheet of sensitized paper is placed behind the tubes and at given. intervals a light is flashed in front of them causing all tubes to register simultaneously. From tests of this character, it has been found, among other things, that the shape of the wing tip has considerable to do with the forces set up. It has been possible by properly designing the wing tips on various types of airplanes, to materially decrease the bending moments in the wing spars without interfering with the aero-dynamic qualities of the plane. This has resulted in lighter construction and consequently slightly increased performance.

As one looks back on the design of the early machines, one often wonders how they were able to hold together. The secret, of course, lies in the fact that their speed was slow enough to prevent excessive loads being thrown on the control service and wings.

When airplanes are designed for government service, a very careful stress analysis is made before the plane is built. This is based on a certain factor of safety ranging from 312 to 12, depending upon the service the plane is to be put to. The first plane which is built to this specification is assembled upside down and supported in a heavy framework. Measuring devices are attached to the wings to indicate the deflection and the planes loaded with shot bags, the first load generally being the entire weight of the plane, fully loaded for flight. Additional shot bags are evenly distributed over the wings, each additional load generally being about onehalf the first load. After each of these loads is in place, the wings are carefully measured for deflection and a careful inspection made to see if any metal fittings or wooden parts show a tendency to weaken. Loads are finally increased to the point of rupture at which time the entire plane generally collapses. The most common point of breakage is in the upper rear wing spar, which is sub

jected to beam loading and excessive end compression caused by the load wires. which transmit their horizontal component to the upper rear spars. The drift wires also have a tendency to give way, particularly in view of the fact that the airplane is tilted upward on its loading frame work to an angle in the neighborhood of 15 degrees, simulating a slight diving position in order to bring into effect the drag caused by the forward motion of the wings through the air.

The weak parts of the airplane thus tested are strengthened on the next machine before it is built, and, if otherwise satisfactory, the plane is next put through very extensive full flight test to determine its air-worthiness and maneuvering qualities.

Airplane races serve two purposes. They stimulate public interest by acquainting the public with the latest development in aeronautics and serve as strenuous full flight tests for the various types of machines entered.

In the average testing of airplanes, pilots are wont to take machines in the air and, when some slight mishap occurs, the plane lands and frequently insufficient attention is given the part which has failed to do its duty. In a race, all pilots are out to get the best possible performance from their machines and many times planes are flown even after oil pressure has dropped, radiators started to leak and gasoline lines failed to function absolutely as they should. While this is dangerous practice, it brings out structural and mechanical defects which might otherwise go unnoticed except for minor repairs. Planes which are competing with one another and particularly those which are evenly matched may win the race on maneuverability. Particularly is this true if one plane has slightly better maneuvering qualities than another and the pilot is able to make cleaner turns and hold to his course without excessive use of his controls.

The ailerons or balancing planes on each wing tip are a serious problem in

designing planes for high speed work. It is generally the tendency to use ailerons of too great size, the result being that the plane over-controls insofar as lateral equilibrium is concerned. Also, at extremely high speeds, it appears that the air stream does not follow the rear portion of the body as smoothly as it does at slightly lower speeds. The

result is that larger fore and aft controls are necessary. This same condition applies with the rudder. It is necessary to have a rudder large enough to insure sufficient control when getting under way on the ground and yet not too large as to cause excessive over-control in flight.

The head resistance which increases with the square of the speed is very carefully taken into account, particularly in high speed planes. This has been carried to a point of great perfection in the airplanes entered in the Pulitzer Race taking place at Bridgeton Field, St. Louis, on the afternoon of October 3.

A very interesting development occurred last year at Detroit in the form of what is known as skin radiators. All of the racing planes this year are equipped with this design of water cooling device. The radiator consists of a double thin sheet of brass which is used as the covering for the wings. Between these thin sheets the water circulates and cools. The result is a wing of no greater resistance and an addition of approximately 15 miles per hour on the planes thus equipped. Under certain conditions this radiator is impracti

cable, inasmuch as, in its present state, it is not possible to blanket the cooling for high altitudes. Also it is very vulnerable to machine-gun fire. External

bracing in the form of exposed wire and structural members has been reduced to a minimum and on the Verville-Sperry racer, which is a thick-winged monoplane, there is absolutely no external bracing and the landing gear completely folds into the wings while the plane is in flight, materially increasing its high speed.

Great as has been the engineering development in aeronautics, there is still an enormous field to be covered. A great deal of airplane design is still based on theories and has yet to be proven practical. This applies to new forms of aircraft such as the helicopter, ornithoptor and other well known departures from the usual trend of design. Unfortunately, aircraft engineering has been devoted in this country principally to military aircraft, although commercial aeronautics has been carried on to a great extent in European countries and it is now possible to go by air lines between practically all of the larger cities in Europe. These transportation lines are run on a business basis and in several cases

are subsidized by the government. Passenger lines are operated with great regularity and it is indeed unfortunate that this phase of aeronautics has not received greater support in the United States. Our Air Mail Lines are second to none and we can at least point with pride to their efficient operation.

The American Society of Mechanical Engineers and the American Society of Refrigerating Engineers will hold their annual meeting in New York, December 3 to 6.

Mr. Baxter Brown attended the Fall meeting of the American Society of Civil Engineers in Richmond, Va., last month. He reports having enjoyed himself thoroughly; incidentally cinching

for St. Louis the annual convention of the society in the Fall of 1927.

Messsrs. Frank H. Schubert and Wm. G. Christy announce the organization of the Schubert-Christy Construction & Machinery Co., with offices in the Rail way Exchange Building.

Mr. Schubert has been for several years District Manager in St. Louis for the Wheeler Condenser & Engineering