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Trivia Testers

If you knew only your true airspeed and your angle of drift from the wind, is it possible to compute the direction and velocity of the wind?

The first aeronautical charts
The first aeronautical charts didn't appear until

  1. 1834
  2. 1888
  3. 1909
  4. 1917

Reinventing the Wheel
In what year did the first "whiz wheel" flight computer appear?

  1. 1881
  2. 1903
  3. 1910
  4. 1917

From whence comes the wind?
If you knew only your true airspeed and your angle of drift from the wind, is it possible to compute the direction and velocity of the wind?

  1. Yes.
  2. Almost, but not quite. You would also need your heading.
  3. No. Not only do you need heading information, but also your original course.
  4. No. In addition to the above, you must know your actual ground speed.

The Answers...

The first aeronautical charts
Answer: There were indeed maps available for aeronauts of the 18th and 19th centuries, but not one of them had been prepared for aerial navigation. Towns were noted in terms of population, not by dimensions or outlines. Railroad maps proved useful for balloonists, although the paths and precise directions of railroad tracks, and at what angles they crossed roads as well as each other, were far from realistic. The first published call for aeronautical charts was made by a Prussian officer and balloonist named Hermann Moedebeck, in 1888. He pointed out that it was difficult to determine safe landing sites from aloft, and suggested that distinctive symbols be used to show such locations. Actual production of such charts however, was still over 20 years away. In 1900, a subcommission of the Second International Congress of Aeronautics did consider the problem of locating one's position from a balloon, but the problem wasn't really addressed. In 1906, Moedebeck once again advised that a better means of determining position by representing useful landmarks was needed, and even suggested governmental support. In 1907, the Third Congress of the International Aeronautical Federation (a rival organization) formed an international commission for aeronautical charts, and Moedebeck was appointed as its first chairman. As a prototype he chose a topographical chart being produced by the Royal Prussian Land Survey, which covered middle Europe on a 1:300,000 scale (the "Cologne sheet"), on which he over-printed various aeronautical symbols. It was shown at an exposition in Frankfurt in 1909. (Yes, the answer is choice C.) Also in 1909, a commercial firm sold an aeronautical chart of Paris; in 1910 the Aero Club of France organized a cartographic commission, and by 1911 it had received a subsidy from the Ministry of Public Works. In the fall of 1911, the first air chart ever made in the US appeared. It was a chart of western Long Island, made for the Aero Club of America.

Reinventing the Wheel
Answer: Especially because the first aircraft flew so slowly, interest in quantifying the effects of wind on the path of an airplane or airship was more than incidental. Very quickly, the more mathematically inclined realized the value in vector diagrams and trigonometry. By using vectors to represent the respective directions and velocities of both wind and aircraft, connected head-to-tail as arrows representing a convenient interval of time, the resultant side of such a completed wind triangle revealed the path it would most likely take over the earth's surface. This was discussed in popular aviation magazines as early as 1910, as was a description of a "compass for aerial navigation" (in that same year). Loxodromic curves may be mathematically elegant, and arriving at one's destination pointed right into the wind may seem convenient, but such a course is inefficient. Pilots knew that "overcorrecting" into the wind to "kill the drift", so that a given landmark always remained at the same relative bearing (until overflown, of course) was the best way to fly. But not all flights were over land, for short distances, or in fair weather. In such cases, one needed the right heading to which the "steering compass" or directional gyro would help guide an aircraft most directly to wherever it was going.

It wasn't until World War I that the dead reckoning computer came into widespread use. (Until that time, aviators had precious little advance information of the winds aloft, but during the war, weather stations were able to provide informed estimates, at least.) The first such devices took the form of adjustable rulers, which were not so easy to use while also manipulating a chart in a cockpit. The second form was a rotating gridded circle, called a Course and Distance Calculator by the RAF, and was derived from a naval instrument. Having a graph and two movable arms, positioned to represent the known values of the wind triangle and clamped in place with an adjustable screw, the user could then simply read off the unknown component against the graph. A circular slide rule on its periphery complimented its functionality. The correct answer is choice C.

From whence comes the wind?
Answer: Solving a navigation problem like this usually involves (and depends upon) one's first knowing true airspeed, ground speed, course, and heading. That's right out of private pilot training. Aha, but there's a trick here. The correct answer isn't a simple "yes"--scratch choice A--but you actually don't need to know original course, nor your ground speed. (The answer is choice B.) How could that be? By using two wind triangles, making two successive runs in two different directions, and then pooling the data, as shown in the diagram below, the wind vector could be taken in common and solved graphically. Obviously such consecutive runs should be made at the same altitude, in the same area, and as close together in time as possible. (A device, later called a "wind-gauge bearing plate," was first fashioned to solve such a wind star by a lieutenant colonel in the Italian Air Force.) By using the two wind triangles together and having the wind vector in common, the both triangles can be solved. Once the headings, airspeed (presumably held constant), and drift angles are known, the ground track can be determined (using heading, plus drift). The intersection of the two heading lines connected in turn to the intersection of the two drift lines would reveal the wind velocity (that is, both its direction as well as its speed).

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