Angles of Ascent, from Victor Niederhoffer

May 31, 2011 |

I have recently been considering the angle of ascent as a predictor of subsequent movements as part of a general consideration of the principles of conservation of momentum apliccability to markets. Here's one approach.

Consider all moves during a week of 10 to 20 full points i.e. 1% in s & p

```.                  number of obs  move the next day     sd
.previous Wed
.to Friday
.up more than 10     44            -2                   13
.up btwn 5 and 10    27            -1                    9
.up btwn 1 and 5     14             0                    0
.-5 < sp <0          11            0                    12```
`.sp < -5              9           20                    22`

There would seem to be some small evidence that for weekly moves during the 1st 10 years, given that the move during the week was between 1 and 2%, the algebraic speed of ascent in the last part was negatively correlated with the move the next day. The approach has many bifurcations and variations and might be interesting to the physicists in our audience.

Chris Tucker writes:

Angles are important in aviation, we use quite a few. Pilots differentiate between angle of climb  and rate of climb. Best angle of climb will provide the most vertical gain over a specified distance, which is handy for clearing obstacles like trees off the end of a runway. Best rate of climb will gain the most altitude over a specified period of time. Not the same thing.

Angle of incidence, a fixed value, is the angle between the chord line of the wing and the longitudinal axis of the fuselage and is not to be confused with the all important angle of attack, the angle between the chord line of the wing and the airflow through which it is travelling. Lift generally increases with angle of attack to a maximum point, the critical angle of attack, after which it decreases because the laminar flow of air over the wing begins to separate from the surface of the wing creating a stall condition. (Nice illustration and mention of tennis and golf balls here.

A serious stall involves a complete loss of lift and often results in a spin and frequently ends in tragedy, as in the loss of Air France Flight 447  and the most recent fatal crash in the United States, Colgan Flight 3407.

The thing to consider in aircraft when looking for a superior rate of climb is high thrust to weight ratio and light wing loading. Pilots can cheat, however, by accelerating during level flight and trading this kinetic energy into a single burst of high speed climb. This is known as a zoom climb and I have suggested the use of this maneuver on occasion to convince pilots to penetrate a layer of severe turbulence if the layer is thin enough and there is smooth air above. It is critical to have current and accurate information about the turbulence before attempting something like this. The important thing about a zoom climb is that it is unsustainable and is bounded by the amount of available kinetic energy. Military fighter aircraft, with extremely high thrust to weight ratios need not be concerned with this as they are capable of sustained and extreme vertical speeds. But they burn an awful lot of fuel in the process.

(Sorry for all the links, when I start talking about flight I tend to get carried away….)

Pitt T. Maner III writes:

Played tennis one night many years ago under the lights with a commercial pilot from Nevada who had a naval aviation background and he described the difficulties of landing a jet on an aircraft carrier under low light conditions in fairly rough sea. What he described was having to concentrate, I think, on the pitch, roll and yawl and coordinate it with the similar movement of the carrier flight deck—lots of variables in a short time window and positional awareness. Very harrowing procedure in difficult conditions (it sounded nightmarish, and one for only the most experienced pilots) and he used the term "bought the farm" several times to describe pilots who had crashed in such circumstances.

What was interesting was a technique he described as powering up and down so as to maintain control and complete the landing. Too much power and he would overshoot and too little and he would stall out or not make the deck. It sounded like revving an engine. Short bursts of power on and power off.

Is that a technique that is taught or does that come from experience and feel?

By coincidence it is the 100th Anniversary of carrier landings. Even with the technological advances pilots must very skilled:

"On Nov. 14, 1910, Ely ignored storm clouds and took off in a spindly aircraft from the USS Birmingham, which sat in the waters of Hampton Roads. It was the first time an aircraft had ever lifted off from a ship.

A photograph freezes the moment in time that Ely became airborne. Yes, that would be him, dropping toward the water.

The flight came perilously close to failing. Ely dove toward the water to gain speed and pulled up, but not before his wheels and part of his propeller struck the water. The aircraft climbed into the air, rattling with damage. Steering with his shoulders — aircraft of that day were built by bicycle makers, and were steered by leaning — he managed to land on the beach at Willoughby Spit.

Then in January 1911, Ely closed the historical loop by landing on the deck of a ship. This time, the event was in San Francisco and the ship was the USS Pennsylvania.

Later that year, Navy brass became convinced to give these new-fangled flying machines a try, and put in the first order for aircraft. That makes 2011 the official 100th anniversary of naval aviation.

Many events are planned for next year, but the Navy will get a head start on the celebration come Friday, with a celebration and a display of older aircraft. Coolbaugh's replica is closer to the aircraft that Ely landed out in San Francisco in 1911, as opposed to the one that took off from Hampton Roads a few months earlier. Still, he had hoped to fly his aircraft off the deck of the USS George H.W. Bush as a tribute to Ely's first take-off."

Here is the wiki for Eugene Ely.

"It's a dangerous job"

And an interesting video here.

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