As a little boy in Holland I was enraptured by the original shape of the Fokker G-1 fighting plane of 1939. A few years later I became a (small) close witness to the atrocities of the war, as some of my schoolmates and good neighbors in the street where I lived in Amsterdam were deported because they were Jews. (They never returned.)
While living now in California and enjoying my own ‘Indian Summer’, I found on the web the designer of the G-1, Erich Schatzki. I also learned that he was a Jewish exile and that he and his family had been on the run for the Nazi’s since 1934. I set out to find more facts about his life.
I have collected these in an ‘Album’, a collection of factual items and a description of some of the fascinating people that he met in his long, adventurous life.
I have added my findings in a new file on my website today. If anybody can tell me more, or if somebody wants to correct an error, please leave a note!
Sikorsky’s factory in Stratford Connecticut completed its first S-42 airliner/flying boat in March 1934 and Igor Sikorsky took at the earliest opportunity the mail boat to Southampton to promote his revolutionary clean looking flying machine in the Old World. His first stop was London where he delivered a glowing lecture with epidiascope projections to the Royal Aeronautical Society. His new ship was fast and it could move passengers far. In fact in the years that followed, Pan American Airways bought ten of them and used them to conquer the Pacific Ocean. The British aviation bigwigs and tech wizards listened in polite astonishment. Igor gave a glowing account of his breakthrough in the design dilemmas that had for thirty years produced only ugly-looking mechanical flying things with a multitude of wings, struts and wires.
Sikorsky had now created a roomy airplane with a single sleek small wing and four beautifully mounted engines. It carried 12 passengers with ease over 2000 miles and it could alight gently at 65 mph on the tops of the rolling waves. Its cruising speed was 160 miles per hour and Igor repeatedly pointed out how this speed in combination with the high wing load made for a comfortable ride, relatively insensitive to wind gusts and sudden vertical up and down air drafts.
IGOR I. SIKORSKY (1889-1972)
The British listened with polite amazement and suppressed skepticism. “We don’t really need speed”, said Mr. Horace Short, the builder of England’s famous double-breasted multi-wing lumbering patrol boats during the discussion afterwards.”When we need speed we’ll have Supermarine win the Schneider Cup or Messrs. de Havilland will build the Comet for winning the Melbourne race. We focus on other things.” He meant safety, a slow landing speed. And it must be said, his boats had an enviable safety record (but could not cross the ocean).
Mr. M.Langley inquired whether Mr. Sikorsky had used Imperial or US Gallons in his specifications. He apparently couldn’t believe the figures and the British ones were a good deal larger.
As to performance, Mr. W.O. Manning conceded frankly that Mr. Sikorsky had put the flying boats used by Imperial Airways completely out of date. He then proceeded to produce a global new design on the lines of the S-42 and showed its superiority.
Major R.E. Penney thought the secret of Mr. S.’s boat could be found in the enormous amount of detail work, the fairing up of the details so that the combined resistances had been reduced to an absolute minimum.
Mr. Scott-Hall mentioned in passing that albatrosses (the birds) had a large wing load but they had trouble getting themselves up in the air. And so there was a lot of back and forth talk about speed and small wings.
Until finally Major F. Green hit on the real issue: “Let’s not overlook the fact that a small wing saves a substantial amount of weight”. And here was of course the quintessence: instead of carrying wing, the airplane could now carry fuel and people. But even Igor did not seem to quite grasp the point. He came back to the subject of speed. “There is no doubt”, he stated, “that planes of great weight, capable of non-stop ocean flights, cruising between 150 to 200 miles per hour, can be designed at this time and be ready for service within two and a half to three years. Greater cruising speeds are possible, but the size of the earth does not warrant greater speeds. The progress of air transportation will benefit more if designers will give more attention to increased passenger comfort and ways and means to lower transportation costs rather than greater speed.”
Well now, would that really be possible Mr. Sikorsky? Are speed and economics independent quantities?
A cat is not a dog and a plane is not a ship.
We exchanged some polite remarks while we heaved our bags in the rack above us and sought our proper place. We just fitted in our seats together: the blonde lady in sweater and jeans at the window, I in the middle and to my right the middle aged guy in safari jacket with long hair in a ponytail… Then we underwent in silence the start of the machine and the handout of some gorgeous delicacies like peanuts wrapped in tiny little plastic bags.
After a while the plane had climbed to cruising height and I bent forward to the left to look out of the window. I saw an elegant upward turned wing tip against the hard blue expansion of the universe and the faintly curved horizon of our planet.
“Isn’t it amazing?” the lady smiled at me – “how we are sitting here crunching peanuts above the world?”
“It’s stunning,” I agreed. – “I was also observing the wing tip. There seems to be a fashion nowadays to bend them upward.”
“Well dear, it’s all about saving fuel you know. The proper shape may give you an extra 3 or 4 per cent range. It all counts with the present fuel prices.” (This conversation took place some years ago).
“How can that be?”
She explained: “The wings leave behind a corkscrew of whirling air, one at each side. It is an air vortex. In a way you may say that the airplane pulls the vortex forward. The bigger the vortex, the more energy it takes from the plane. With careful design of the wing tip the engineers try to make the generation of the vortex more gradual, less violent, see?” She looked at me and smiled.
“Yeah,” the man to my right added -“and these vortices are bloody dangerous for the little guy who is flying behind them. You better stay out of the wake of the big ones…”
And so it turned out to be a pleasant flight for all of us. The safari chap ordered a meal and offered me his dessert because he was, as he explained, a diabetic. The lady at the window knew more about airplanes than any of us. And I told them about Willy Fiedler who had built and flown a sailplane in 1933 with vertical wing tips and no fin at the tail. I even showed them a picture on my i-phone.
They were properly impressed.
We spent the rest of the flight with pleasurable chitchat. However, as always when flying, I lost my new friends at the Luggage Claim. If we had traveled by steamship we would probably still be in contact now.
DescriptionAirplane vortex edit.jpg (see earlier picture)
Date 4 May 1990 English: Wake Vortex Study at Wallops Island
The air flow from the wing of this agricultural plane is made visible by a technique that uses colored smoke rising from the ground. The swirl at the wingtip traces the aircraft’s wake vortex, which exerts a powerful influence on the flow field behind the plane. Because of wake vortex, the Federal Aviation Administration (FAA) requires aircraft to maintain set distances behind each other when they land. A joint NASA-FAA program aimed at boosting airport capacity, however, is aimed at determining conditions under which planes may fly closer together. NASA researchers are studying wake vortex with a variety of tools, from supercomputers, to wind tunnels, to actual flight tests in research aircraft. Their goal is to fully understand the phenomenon, then use that knowledge to create an automated system that could predict changing wake vortex conditions at airports. Pilots already know, for example, that they have to worry less about wake vortex in rough weather because windy conditions cause them to dissipate more rapidly.
When, in 1953, in my capacity of apprentice in the KLM Maintenance Service at Schiphol, I started one morning to help take off half the wing of a Douglas DC-3, I was most astonished to find that the wing of this rather famous and historic airliner had no sturdy spar in its innards, but that the metal wing cover had a seam from front to back at a position close to the engine, where it was simply bolted to the center section of the airplane.
Only recently I read that this particular construction was called ‘multi-spar’ and invented by Jack Northrop around 1930. In document 3-22(a-b) 3-22-b: Engineering Department, Douglas Aircraft Co. “Development of the Douglas Transport”, Technical Data Report SW-157A, ca. 1933-34, Folder AD-761184-05, Aircraft Technical Files, National Air and Space Museum, Washington, D.C., one can find:
“In the Douglas and Northrop types of multi-cellular wing construction, there are a multiplicity of full length span-wise stiffeners, and the fact that they have no abrupt changes or ‘breaks’ [in their extended shape] results in no concentration of stresses. With the centroids of the stiffeners located at the maximum distances from the neutral axis of the [wing] section, a most efficient structure for absorbing the bending load is obtained.”
In my interpretation this means that the outside skin of the wing (well reinforced with span-wise stiffeners) will absorb all the bending stresses and that one can dispense with heavy spars directly connected to the fuselage. The remainder of the text is too interesting to be omitted, as we, modern airline customers, only too well know how scary modern airliners sometimes flex their wings:
“In a highly stressed airplane, torsional rigidity of the wing is of paramount importance in the prevention of wing flutter at high speeds and torsional deflection of the structure must therefore be kept to an absolute minimum. When under load, there will always be some vertical deflection but this must not be excessive since a wing with large vertical deflections might cause jamming of aileron controls and by no means inspires confidence in the passengers or pilots.”
Also, vibrations can generate most annoying noise (I remember flying in the Vickers Vanguard in 1962):
“If unsupported flat metal surfaces are even moderately large, there is always a tendency for the middle of the surface to vibrate in flight, even when there is no stress. This is termed ‘oil canning’and will, in time, cause fatigue in the sheet metal and in the rivets and cause rivet heads to work and to pop off. These unsupported flat surfaces continually drum and cause a noise that cannot be completely eliminated in a cabin, because part is carried as vibration thru the structure. This is different from ‘wrinkling’of the skin. Wrinkling will be present in every metal wing with a flat metal covering taking stress. These wrinkles are deflections of the skin under load and ordinarily do not have any tendency to vibrate.”
The report continues with more on the subject of the wing design for the early Douglas airliners:
“In determining the wing construction of the early Douglas machines single, two, three and multi spar designs were considered as well as shell type and multi-cellular designs. After a thorough investigation of all types the Northrop multi-cellular wing construction was finally decided upon. This type of structure consists of a flat skin reinforced by numerous longitudinals and ribs. The bending is taken by the combination of flat skin and full length [longitudinal] stringers. Three main flat [vertical] sheets or ‘webs’ carry the shear loads. Torsion and indirect stress are carried by the skin with frequent ribs preserving the contour and dividing the structure up into a number of small rigid boxes or cells. Since the major loads are carried in the outer surface of the wing as well as in the in the internal structure, an inspection of the exterior gives a ready indication of the structural condition. The unit stresses in the material are low and therefore the deflections are at a minimum giving a maximum in rigidity. This construction has proven to be a happy medium of those considered since it combines practically all of the advantages of each; namely, very small unsupported areas, extreme lightness for its strength and rigidity; also ease of construction, inspection, maintenance and repair.“
For the early Douglas airliners:
“The Northrop wing being comparatively small, it is economical to have many of the stringers run from the top to the bottom of the wing as shear webs or spars. However, when the principle is carried out on a larger scale, as in the DC-1 with its deeper wing, it is more efficient to have only three shear webs or spars. Thus it was not necessary to evolve a new type of structure but merely to adapt a time proven type to the dimensions of the DC-1.” [end of quote]
The exterior wing was fastened to the center section with a great numbers of bolts. It was my task to receive each bolt, nut and washer that became undone and secure them in a numbered hole in a plywood board. In the end there were 20 boards with a total of 652 bolt sets. My mentors /colleagues worked according to strict KLM protocol [see the following drawing which I owe to Mr. Wim Snieder, The Hague, Holland] and had the use of an overhead crane.
We finished unbolting the [half] wing by 3 pm and went for tea, delivering on our way the boards with fasteners at Testing for examination on hair cracks and corrosion.
Willy Fiedler was a remarkable German/American aviation engineer, test pilot
and development scientist in Missiles and Rocket propulsion.
He is remembered by many as a cheerful, congenial person who made important contributions in his field of endeavor.
I am posting today on my site a page that describes the history of the design effort of ISAAC MACHLIN LADDON to create that remarkable flying boat, the PBY CATALINA.
Press the tab at the top of the screen or you can download the story directly from here: LADDON CATALINA
airplane construction interbellum – like Rohrbach and many other pioneers