The boss I never met

I never met my first boss. This happened 15 years ago; the shock, the sadness, and his sister’s voice on the phone are still here. Thanks for the opportunity Mr. Carlson; I’m sorry that we never met.

From the NTSB accident report:


NYC00LA141

On May 24, 2000, about 0930 Eastern Daylight Time, a homebuilt Criquet, N22CA, was destroyed while departing Aero Flight Center Airport, East Palestine, Ohio. The certificated private pilot/owner was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91.

 

A witness at the airport stated that the pilot initially performed a full power run-up, then shut the engine down. The pilot told the witness that the engine was producing 50 to 100 rpm less than maximum power. The pilot adjusted the carburetor, restarted the engine, and performed another run-up. During the second run-up, he checked both magnetos, but did not perform a full power run-up. The airplane then departed on Runway 29, a 3,000 foot long, 100 foot wide turf runway.

The witness added that the airplane usually used about “half the runway” to takeoff. On the accident flight, the airplane used about “three quarters of the runway.” It then made a right turn to avoid trees, but struck a tree with the right wing. The airplane came to rest inverted in a bean field, and a post crash fire ensued. While examining the wreckage with a Federal Aviation Administration (FAA) inspector, the witness stated that the supercharger appeared to be disengaged.

Another witness, who was a retired mechanic, stated that he was familiar with the airplane. The airplane’s engine was a Lom Praha M332AK, manufactured in the Czech Republic. Several months before the accident, the pilot noticed the engine was not producing maximum power. The mechanic examined the engine, and found a leak in the exhaust valve of a cylinder. The cylinder was repaired at a machine shop and reinstalled; however, the engine still did not produce maximum power.

The pilot eventually sent the engine back to the manufacturer for repair. While the engine was being repaired, the manufacturer provided the pilot with a “loaner” engine. The mechanic stated that the airplane performed much better with the “loaner” engine, and the pilot never had any problems.

The pilot’s original engine was returned without any paperwork. According to the mechanic, he and the pilot did not know what repairs were made to the engine. The pilot and mechanic reinstalled the original engine.

On the day of the accident, the pilot performed one run-up near his hangar. He performed a second run-up at the end of the runway that lasted approximately 20 minutes. The mechanic stated that the airplane used about “two thirds of the runway” for takeoff. As it became airborne, the engine “sounded ok,” but the airplane did not seem to have enough airspeed or altitude. It struck trees at the end of the runway and a fire ensued.

When asked about the lack of power, the mechanic stated that there might have been something wrong internally with the engine. He said that he wasn’t sure, but that the engine was “lazy.” When asked about the supercharger, the mechanic stated that the pilot may not have engaged it. He added that the supercharger didn’t make a noticeable difference when it was engaged or disengaged.

A Federal Aviation Administration inspector examined the wreckage. He stated that due to the post crash fire, he was unable to verify flight control continuity or conduct an engine examination.

The airplane was issued a temporary, 3 month, special airworthiness certificate on May 27, 1999, by a FAA inspector. After the certificate expired, and the original engine was reinstalled, no FAA inspector had examined the airplane.

At 0950, at an airport approximately 10 miles away, the reported wind was from 250 degrees at 15 knots.

The pilot’s most recent FAA third class medical certificate was issued on August 17, 1996. At that time, he reported a total flight experience of 2,000 hours. According to the airplane logbook, it had approximately 8 hours of operation.

Toxicological testing, conducted at the FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma, was negative for drugs and alcohol.

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First Thermal

My first, second, and third thermal! Finding and soaring in thermals is a new experience for me.

I’ve read the books (“Joy of Soaring”) , devoured the “Soaring” journal (back as an undergrad), and even tried to simulate a sailplane with a Cessna (lousy idea). However, yesterday was the first time that I’ve actually done so with an airplane capable of soaring.

The plane is a Dreamflight Libelle DLG.

Joukowski Transform

\(\) The Joukowski transform is a stunningly simple mathematical operation that converts a circle into an airfoil.

$$w=z+\frac{c^2}{z}$$

The beauty of the transform is that ideal fluid flow past a circle is described by a classic and well known set of terms.

joukowskicylinderflow

I made a small visualization program that allows experimentation with a Joukowski airfoil in an ideal fluid flow environment. This is meant to illustrate conformal mapping to my GES 554 class and airfoil theory to AEM 614.

Tapered Barrel Volume

A while ago, my parents’ neighbor asked a good question: For a tapered barrel, is there an equation for the volume versus height? Here’s what I came up with.

When comparing the volume ratio for specific barrels, the following fill curves occur:

Tapered-Barrel

Now holding a constant maximum radius, the following absolute volume ratios (compared to the straight sided barrel) occur:

Tapered-Barrel-2

Rules of thumb:

  • The fill-volume ratio is approximately (±15%) linear with height when the upper to lower radius ratio is within 2:1.
  • Half the volume of a cone is at the 20% height level.

The final recommendation was to fill the barrel with a known volume (gallons) and mark the side.

Crimson Aviators Photo

Crimson Aviators Cookout 2015

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The Crimson Aviators university student club holds regular meeting at the Tuscaloosa Alabama airport (KTCL). The club is operated by University of Alabama students. I am the faculty adviser on the far right. More information is available at Crimson Aviators.

Thanks to Abe Alibrahim at www.generalaviationcenter.com for hosting the club, and providing generous hanger space for meetings. For aircraft rentals and flight training in the Tuscaloosa area, contact Abe at 205-345-5900.

How the future of drones is set in the past

How the future of drones is set in the past.
or
How one event 100 years ago will replay again.

The date was 1915. The place was Western Europe. The event was the arrival of aircraft meant to kill. This was the birth of fighter aircraft. Before that time, military aircraft were used as spotters. In the US – Mexican “Border War” (1910-1919), the US Army first fielded aircraft; Mexico fielded no opposing aircraft. In 1914, the nature of aircraft changed and evolved into three standard categories: observation, bombers, and fighters. (As an aside, the transport came later.)

We can pin the date of which the fighter aircraft came of age: The Fokker Scourge, July 1915. The critical question for the 21st century is, “What is the drone analog of the machine gun interrupter?”

Will  drones kill drones? In a word, yes.

Well, we know that on a traditional symmetrical battlefield, everything that flies will be hunted. Both bird and machine will be eliminated ruthlessly.

But on the asymmetrical battlefield and the rule-of-law environment, the nature of drones will become extraordinary. Expect bio-mimicry to make drones functionally and visually indistinguishable from bird, insects, and plant matter. The great hunt will be classification and potentially elimination of the unwanted machines. EM transmissions will be a giveaway and will either result in high gain antenna systems with burst transmissions (aka. WW2 submarines)  or fully autonomous vehicles. The whine of a propeller, gearbox, or motor will be a dead giveaway.

How will drones kill drones? Ruthlessly autonomously. Hawks vs. Watchbirds

Solving a Convection PDE

The problem under consideration is a linear convection PDE.

\(\) From Farlow’s “Partial Differential Equations for Scientists and Engineers”, chapter 15 problem 3 is $$u_t = -2u_x \quad -\infty < x < \infty \quad 0<t<\infty $$$$ u(x,0)=e^{-x^2}$$

Intuition

We see that the governing equation is a linear convection problem. The characteristic velocity is 2. We expect the solution to be a shifted initial condition $$u(x,t)=e^{-(x-2t)^{2}}$$

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Standard Atmosphere and Airspeed

This post provides a visual characterization of a generic flight envelope with a standard atmosphere. The following figure shows a generic flight envelope map.

KCAS, TCAS, Mach, Dynamic pressure, Temperature

Atmosphere and Airspeed

A pdf version is available at airspeed-2014c.pdf. This file plots altitude (0 to 50 thousand feet), calibrated airspeed (0 to 1000 KCAS), true airspeed, Mach number, dynamic pressure, static pressure, and total temperature on one handy page.

Airspeed:

Engineers and pilots track three different speeds:

  1.  Calibrated Airspeed: the airspeed from the pitot system corrected for instrument bias
  2. True Airspeed: actual speed through the air
  3. Groundspeed: speed referenced to level ground

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F-35 Economy of Scale

Photo (c) Andy Wolfe

Photo (c) Andy Wolfe

The F-35 Joint Strike Fighter (JSF) was conceived as a 5th generation fighter with a tri-service economy of scale. The late 1990s philosophy is stated as: “The rising unit costs of military aircraft and the new emphasis on greater commonality of aircraft designs among the services tended to push procurement trends toward ever smaller numbers of even more complex and expensive fighters designed to offer multirole and cross-service capabilities. [1]” A post-design analysis by RAND 20 years later estimates that the JSF’s life-cycle cost is 65% higher than a single-service fighter rather than the promised 16% lower life-cycle cost [2]. As of mid-2014, the F-35’s flight envelope is restricted to Mach 0.9, 3 g’s, and 3 hours between engine inspections [3]. Question: what is the subsequent impact to F-16 and A-10 mission replacements if the F-35 program continues having fielding issues?

[1] M. Lorell and H. Levaux, The Cutting Edge: A Half Century of U.S. Fighter Aircraft R&D, RAND, 1998.

[2] M. Lorell, M. Kennedy, R. S. Leonard, K. Munson, S. Abramzon, D. An and R. Guffey, Do Joint Fighter Programs Save Money?, RAND, 2013.

[3] A. Mehta, “Some F-35 Flight Restrictions Lifted,” DefenseNews, 2014. [Online]. Available: http://www.defensenews.com/article/20140729/DEFREG02/307290036/Some-F-35-Flight-Restrictions-Lifted.