To the Editor: I have been following the media accounts of the American Airlines Flight 587 Airbus disaster. As reported, the vertical stabilizer fin was designed as a complete composite structure, including the mounting lugs. My interest was aroused since my master's thesis subject was on
design criteria for composite columnar structures.

I was quite surprised to see that the Airbus fin mounting lugs were also made of composites, which according to the media photos were the primary failure points. Because of the low bearing strength of the composites, I would have expected the mounting lugs to be metallic and extended well into the fin composite body to distribute the lug loads.

This composite housing has metal fasteners.

As a senior design engineer at Solar Aircraft Co. (now Solar Turbines), I designed an aerodynamically enclosed gas turbine generator set to supply auxiliary power to a Convair 240 civil aircraft to be used as an electronic test bed for the Air Force. The design criteria involved aerodynamic loads and landing and takeoff loadings. The removable aerodynamic housings for the gas turbines were made of fiberglass reinforced phenolic resins.

All attachments to the interior turbine structure were with quick disconnect fasteners and metallic ferrules embedded in the composite matrix to withstand the bearing load and distribute it through the material. Extensive field testing revealed no failures during the life of the program.

Although recent statements indicate that the loss of Flight 587's vertical fin resulted from extreme turbulence from a preceding aircraft wake, and some pilot actions, viewing of the failed attachment lugs seems to indicate that a complete design integrity review is in order.

Editor's note: About three minutes after taking off from Kennedy International Airport on Nov. 12 last year, American's Flight 587 crashed in the Rockaway section of the New York borough of Queens. The crash killed more than 250 people in the aircraft and five on the ground.

To the Editor: Bravo. Stan Jakuba's story, "Standard Measure," (April 2001) ought to be read aloud at the beginning of every engineering class and presented as the first paper at every symposium and professional meeting.

What must be done to cause all P.E. exams to be given in SI terms only? That would induce professors of engineering to at least make their students conversant in those units. I know of professors in our state who absolutely refuse to use any SI units in their teaching of our new engineers. Coupled with publication refusals for non-SI articles, metric-only P.E. exams might help move the field's practitioners to metricate.

About a year ago, I gave a 1.5 h talk on the status of metrification before the South Carolina Society of Professional Engineers. It was an eye-opening experience for me, as well as for the audience (I hope). One engineer (probably in mid-career) insisted that there were two kinds of liters—dry and fluid. He could not be dissuaded. Many thought the calorie was an SI unit and didn't know whether they should wear a jacket when the temperature was 29°C.

To the Editor: I think that your magazine is really a great publication for delivering high-tech information, at a readable level, to a semi-informed audience. Having been a magazine editor in the past, I think you are doing a good job in both content and presentation.

However, Barbara Wolcott's article, "Solar Gains," (October 2001) contains some information that is so inaccurate that it does not become a magazine like yours. I would like to point out some examples:

"Solar will contribute between 3 and 4 percent of the country's [meaning Germany] total installed generating capacity, which exceeds 10,000 MW."

First of all, I don't know what Germany's total generating capacity is exactly, but I can tell you Turkey's: 30,000 MW. I would guess that Germany's total capacity will be in the hundreds of thousands of mega-watts. Second, solar is no way near producing even

1 percent of the total electrical need of any industrialized country. Don't get me wrong; it's a great technology, but I think the author has got the figures wrong.

Comparing photovoltaic and gas electricity costs in California: "8 to 20 cents per kilowatt-hour, compared with 30 cents per kilowatt-hour for gas."

I am currently working on the construction of a natural gas combined-cycle power plant in Turkey, and our sale price for electricity to the utility is 4.2 cents per kWh. I have never heard of gas-produced electricity costing more than 6 to 7 cents per kWh. If the prices in California are seriously skewed right now, I am sure that it has to do with the mess-up of the deregulation of the power industry. But even the author refers to a different location in northern California where, she says, prices for the home user vary between 12 and 19 cents.

Again, don't get me wrong; I am not against alternative energy technologies. In fact, the topic of my master's thesis had to do with solar/hydrogen energy. But in a serious magazine such as yours, these kinds of inaccuracies do more harm than good to the cause. I think that as technology develops, as fossil fuel prices rise, and as environmental concerns increase, all alternative technologies will receive more and more attention. But, as engineers, we have to get our figures right.

The Energy Information Administration of the U.S. Department of Energy estimates Germany's electrical generating capacity to be approximately 110,000 MW at the beginning of 2000. The Utility Data Institute in Washington, D.C., puts Germany's capacity nearer 130,000 MW.

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