EN Otto Lilienthal: "FIRST IN FLIGHT" - 7 Seconds for Eternity

Kool

I reckon it would fly better if the tail was removed. It moves about too much and that must induce turning forces that are counter to the forces generated by the mainplanes.

Without It the wings would rotate forward.  Nev

Lilienthal’s empenage looks too floppy and the angle seems wrong, but it’s surprisingly modern. Years before the Wright’s box-kite-derived structure, he used a modern vertical and horizontal stabiliser.

Lilienthal is known as "The father of Modern Hang Gliding" . There were many other pioneers in the 19th century, Percy Pilcher is one I remember but Lilienthals design and detailed documentation of his 1500 odd flights was second to none. Why they did not get a hang glider expert pilot to provide some initial instruction I don't know. Some of the semi rigid hang gliders when I was flying them in the mid/late 70s had parallel bars and moving fore/aft provided pitch control plus weight shift to the side with legs for roll.

Of course the Rogallo design (originally developed as a re-entry wing for space craft that didn't succeed) evolved into the modern hang gliders of today as well as Trikes with the pilot (or fuselage) in a harness attached to the CofG.

The tail feathers are seeking a large angle of attack of the mainplanes but under cambered wings have a large centre of lift travel. and at some angles Of Attack (low), downforces at the front, so that situation has to be avoided. That lay out would have been arrived at by experimentation .  Hargreaves boxkites don't suffer the problem. Nev

The only step forward I see that Lilienthal made was upper surface curvature of the wing. That was an important step and was the basis of the Wrights' research. Based on their measurements, the 1901 aircraft only developed 1/3 of the lift which was predicted by using the Lilienthal data. At the time of the Wright brothers, the reference conditions for the lift and drag was the drag on a one square foot flat plate moving at one mile per hour. Today we base our lift and drag coefficients on the dynamic pressure of the moving air. 

When the Wrights began to design the 1900 aircraft, they used values for the lift coefficient based on the work by Lilienthal. Lilienthal and the Wrights used the .005 value for the pressure factor. During the kite and glider experiments of 1900 and 1901, the brothers measured the performance of their aircraft. Neither aircraft performed as well as predicted by the lift equation. The 1901 aircraft had been designed to lift itself (100 pounds) plus a pilot (150 pounds) when flown as a kite in a 15 mile per hour wind at 5 degrees angle of attack. But in flight, it could barely lift itself in a 15 mile per hour wind at a much higher angle of attack. So the brothers began to doubt the .005 value for the Smeaton coefficient. They determined that a value of .0033 more closely approximated their flight data. They developed a system of measuring the forced of Lift and Drag, using a constant wind velocity generator (wind tunnel), and produced the results that enabled them to build winged machines that would rise above the ground if the speed of the air over the wings was sufficiently fast enough. Since they could not make a wind tunnel big enough for a man-carrying machine, they had to design their machine with the known wind speeds of Kittyhawk in mind. At the end of their 1901 wind tunnel tests, the Wright brothers had the most detailed data in the world for the design of aircraft wings.

We tend to gloss over the actual work the Wrights put into making those first gliders. Their use of the Scientific Method virtually ensured them of success, at least in making a machine that would rise from the ground and remain airborne. Don't forget that in their early excursions off the ground the machine was tethered, simply relying on wind speed and wing design to keep it aloft, like a child's kite. This, no doubt, allowed these excursions to last much longer than any free-flight and, once they had twigged to the way to control roll, let them practice their control skills.

The early engines were down on power and overheated due to a poor combustion chamber design. They didn't even make 20 SHP. The props must have been fairly good converters of torque to thrust to propel the plane. The weak hubs cause a fatality later,  The forward elevator control was typically oversensitive, but I think the Wrights did a LOT for aviation when you add it all up. Glen L. Curtis was quite a brilliant person also.. That era heralded a period of rapid engineering advancement.   It's only 120 years ago. Nev 

Imagine how far along we would be today if the Wright Brothers had not sold their patents to Big Business, which effectively stifled aeronautical advancement in the USA until 1920 when a parsimonious government set up a small organisation to advise on research. That was the National Advisory Committee on Aeronautics (NACA).

I looked up and used NACA research reports from the 30s and 40s. Free to all, including foreigners. A product of America when it actually was Great, when governments actually helped people. Before the Republicans became totally corrupt.

They  published a list of NACA aerofoils designated by an identifying number and wind tunnel tested.  Nev