Monthly Archives: December 2008

Eating in the NASA Cafeteria

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In my peripatetic ways, I have become a connoisseur of the cafeterias at almost all the NASA installations.  In some places there are great restaurants just outside the gates, but I’m cheap and the NASA cafeteria is almost always good basic food at a reasonable price. 

My absolute favorite NASA cafeteria is, or rather was, the White Sands Test Facility cafeteria.  Since I grew up in New Mexico, I really like the regional food and the WSTF cafeteria had the best.  I say ‘had’ because the operation there has changed.  For a long period they had nobody to run the cafeteria and now they have a new operator that I need to test.  I’ll give you an update after my next visit there.

The cafeteria at NASA HQ is one of the best buffets that I know of.  Very eclectic from oriental food to corned beef and cabbage.  Huge salad bar.  Also in the same building they have a small short order grill with very interesting sandwich wraps.

At MSFC they have down home cooking as you might expect in Alabama.  If you like beans and cornbread, greens, or other southern comfort food, go there.  Although, surprisingly, the GRC cafeteria runs a close race for comfort food. They have the best meatloaf of all the NASA cafeterias (and some of the other places make awful meatloaf. I think I’ve tried them all).

The best breakfast award goes to the JPL cafeteria.  They have short order cooks at the grill that make omelettes to order with a wide variety of fresh California produce to spice them up. 

I got the best seafood of any NASA cafeteria at Langley.  Must be because they can get it fresh in the local area.

Dryden serves really good soup — a plus for a place in the desert!

Ames gets the runner up award for the best view:  you can look out the windows at the huge wind tunnels and think about the glory days of aviation research there.  Nowadays Ames is all about computers but somehow the view of a room full of electronics just doesn’t compare with those magnificent wind tunnels.

The best view award goes to the KSC cafeteria at Launch Complex 39.  There are a lot of cafeterias at KSC and they serve great food, but for the view go eat breakfast at LC-39.  The big picture windows face east and you can watch the sun rise over the launch pads.  Wow.  Not to be missed.

And JSC?  Well, it used to be better.  There was a change in management and they went from good basic home food to foo-foo food with fancy names and servers that wear tall chefs hats (always a bad sign) — and the prices went way up.  Hmmm.

But there is the real story apart from the food and prices.  Going to the cafeteria is a place to meet people.  Where else can you go to rub elbows with astronauts, flight directors, program managers, and real rocket scientists?  One table that I pass by almost every day has a rolling seminar in aircraft flight control.  When I was a young flight controller, I was able to sit at the table with the senior Flight Directors and learn the business first hand. 

Now I go to the cafeteria to escape from the office.  If I brown bag it to the office, inevitably the phone rings with some urgent problem and lunch is over before it begins.  Going to the cafeteria gives a respite in the middle of the day. 

But the funniest thing is how much “work” gets done in the cafeteria over lunch.  People that are not on my calendar just run into me in the cafeteria and vice versa.  We can have a 3 minute conversation while waiting in the checkout line and nip a critical problem in the bud.  There are young folks who join at my table and we have conversations about avoiding the mistakes I’ve made in my career and other important topics.  Personnel issues can be resolved over chicken and potatoes.  Technical issues get bubbled up over soup and salads to me long before the official communications chain processes the information. 

In short, going to the NASA cafeteria for lunch is often the best part of my day. 

Probably the most interesting thing is that most folks will tell you things that you need to know over pie and coffee that they would never do in a conference room.  Dissenting opinions can be thrashed out, alternatives explored, possibilities mulled over. 

So, if you see me in your NASA cafeteria, stop by.  Say hello and let me know what you are up to.  Some people feel its an imposition, but its not.  Actually, that is the best part of the day. 

The Radical Wrights

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Yesterday was the 105th anniversary of the Wright brother’s first flight and I thought all evening about their accomplishment.  I dug out my dog-eared copy of Tom Crouch’s excellent biography “The Bishop’s Boys” and read a few paragraphs.  Whenever I can, I visit the Smithsonian’s Air & Space Museum on the national mall to see the second floor room where the “Flyer” is enshrined.

The Wright brothers are held to be the penultimate real-life historical proof that Horatio Alger was right; hard work, ingenuity, and courage can lead to success, fame, and fortune. 

Or maybe not. 

There were a huge number of people working on the problem of heavier than air flight in the early 20th century.  There are competing claims from supporters of many of those early inventers that some of them “beat” the Wright brothers to achieve the first flight.  None of these claims hold up under scrutiny however.  If the Wright brothers had not existed, or had been happy to be merely bicycle makers, someone else would have flow — the only question is how much later.  Based on my study, it probably would have been quite a lot later.  Literally everybody else was pursuing the dead end of making a perfectly stable aircraft. Today we know that is impossible.  The Wright brothers had a different idea: to build a purposely unstable aircraft with adequate controls to allow a human to manage that instability.  Of course that is not all, but imagine the consequences if the Wright brothers had not pursued their inherently unstable aircraft idea.  What would have happened during WWI with no aircraft?  No Red Baron, no Eddie Rickenbaker, no Hermann Goering, no Billy Mitchell, at least not as we know them today.  Only  tethered balloons for artillery spotters — not much different than the American Civil War — and the Zeppelins.  If the invention of the airplane had been delayed by 20 years, would Charles Lindberg Ameila Earhart be remembered today?  And  would the Japanese Imperial Navy have built aircraft carriers by 1941?  History would have been different in ways that we cannot even imagine.

Yet the Wright brothers succeeded because of a confluence of time, capabilities, and events.  If Octave Chanute had not published his work, if internal combustion engines had not sufficiently developed to generate 12 horsepower from an engine weighing less than 150 pounds,  if Bishop Milton Wright had not bought a 50 cent Penaud helicopter toy to bring home to his sons to play with, if the brothers had given up after the failure of their 1901 kite when Wilbur wrote “Not within a thousand years would man ever fly”, if, if, if, if any of a thousand events had unfolded differently, what would have happened?

The Wright brothers invention succeeded because they were the right people with the right knowledge at the right time in history — and because they worked really hard at making their dream a success.

In retrospect, history looks deterministic.  Everything happened as it was supposed to.  Events unfolded according to some cosmic plan.  In reality, we make our own history.  Decisions every day determine what the future will be.    Edmund Burke’s words ought to ring in our ears:  “All that is necessary for the triumph of evil is that good men do nothing.”

Recently there have been a spate of commentators that have decried our national plan to explore space as unrealistic.  That may be a topic for serious debate.  But one argument that they have advanced is nonsense.  The argument that Apollo was successful and could have only happened because of the historical influences of the times, and since the times and world events are different, the successor to Apollo cannot happen today.

Certainly the times and events influenced Apollo and the moon landings and caused certain decisions to be made in certain ways; events may have moved faster or slower had events been different.  All that I grant you.  But to leap from the historical record to the conclusion that no large national (or international!) exploration of space can take place today because the times are different is unwarranted.

This is a time when there is a confluence of capabilities and events.  All that is required is that innovative people work really hard to achieve their dreams. 

And in that way, these times are no different from 1969 or 1903. 

 

 

 

 

 

Factors of Safety

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     Old joke:  “You see the glass as half empty, I see the glass as half full, but an engineer sees the same glass and says ‘it is overdesigned for the amount of fluid it holds.’”

 

     When an engineer starts out to build something, one of the first questions to be answered is how much load must it carry in normal service?  The next question is similar:  hom much load must it carry at maximum?  An engineer can study those questions deeply or very superficially, but having a credible answer is a vital step in at the start of a design process. 

 

     Here is an example.  If you design and build a step ladder which just barely holds your weight without breaking, what will happens after the holidays when your weight may be somewhat more than it was before you eat Aunt Martha’s Christmas dinner?  You really don’t want to throw out your stepladder in January and build a new one do you?  Obviously you would should build a stepladder that can hold just a little bit more.  Don’t forget what might happen if you loan your stepladder to your coach-potato neighbor who weighs a lot more than you do?  Can you say lawsuit?

 

     So how do you determine what your stepladder should hold?  Do you find out who is the heaviest person in the world and make sure it will hold that person?  Probably not.  Better, pick a reasonable number that covers, say, 95% of all folks, design the ladder to that limit and put a safety sticker on the side listing the weight limit.  Yep, that is how most things are constructed.

 

     But that is not all.  Once you determine normal or even the maximum load it is a wise and good practice to include a “factor of safety”.  That means that you build your stepladder stronger than it needs to be.  This helps with the idiots that don’t read the safety sticker; it also helps protect for some wear and tear, and it also can protect if the actual construction of your stepladder falls somewhat short of what you intended.  So you might build your stepladder with a FS of 2.  That would cover 95% of all folks with plenty of margin for foolish people that try to accompany their friend climbing the ladder; or when your ladder has been in service for 25 years (like mine), or when your carpenter buddy builds the stepladder with 1/4” screws rather than ½” screws like you told him to.

 

     Factors of safety are not pre-ordained.  They have been developed over the years through experience and unfortunately through failures.  Some factors of safety are codified in law, some are determined by professional societies and their publications, and some are simply by guess and by golly.  Engineering is not always as precise as laypeople think.

     

     It’s a dry passage but I’d like to quote from one of my old college textbooks on this subject (Fundamentals of Mechanical Design, 3rd Edition, Dr. Richard M. Phelan, McGraw-Hill, NY, 1970, pp 145-7):

 

“ . . . the choice of an appropriate factor of safety is one of the most important decisions the designer must make.  Since the penalty for choosing too small a factor of safety is obvious, the tendency is to make sure that the design is safe by using an arbitrarily large value and overdesigning the part.  (Using an extra-large factor of safety to avoid more exacting calculations or developmental testing might well be considered a case of “underdesigning” rather than “overdesigning.”)   In many instances, where only one or very few parts are to be made, overdesigning may well prove to be the most economical as well as the safest solution.  For large-scale production, however, the increased material and manufacturing costs associated with overdesigned parts result in a favorable competitive position for the manufacturer who can design and build machines that are sufficiently strong but not too strong.

            As will be evident, the cost involved in the design, research, and development necessary to give the lightest possible machine will be too great in most situations to justify the selection of a low factor of safety.  An exception is in the aerospace industry, where the necessity for the lightest possible construction justifies the extra expense.”

            “Some general considerations in choosing a factor of safety are  . . . the extent to which human life and property may be endangered by the failure of the machine . . . the reliability required of the machine . . . the price class of the machine.”

 

            Standards for factors of safety are all over the place.  Most famously, the standard factor of safety for the cables in elevators is 11.  So you could, if space allowed, pack eleven times as many people into an elevator as the placard says and possibly survive the ride.  For many applications, 4 is considered to be a good number.  In the shuttle program the standard factor of safety for all the ground equipment and tools is 4.  

 

            When I was the Program Manager for the Space Shuttle, there were a number of times when a new engineering study would show that some tool either could be exposed to a higher maximum load than was previously thought, or that the original calculations were off by a small factor, or for some reason the tool could not meet the FS of 4.  In those circumstances, the program manager – with the concurrence of the safety officers – could allow the use of the tool temporarily – with special restrictions – until a new tool could be designed and built.  These “waivers” were always considered to be temporary and associated with special safety precautions so that work could go forward until the standard could once again be met with a new tool.

 

            In the aircraft industry, a factor of safety standard is 1.5.  Think about that when you get on a commercial airliner some time.  The slim factor of safety represents the importance of weight in aviation.  It also means that much more time, engineering analysis, and testing has gone into the determination of maximum load and the properties of the parts on the plane.

 

            For some reason, lost in time, the standard FS for human space flight is 1.4, just slightly less than that for aviation.  That extra 0.1 on the FS costs a huge amount of engineering work, but pays dividends in weight savings.  This FS is codified in the NASA Human Ratings Requirements for Space Systems, NPR 8705.2.  Well, actually, that requirements document only references the detailed engineering design requirements where the 1.4 FS lives. 

 

            Expendable launch vehicles are generally built to even lower factors of safety:  1.25 being commonplace and 1.1 also used at times.  These lower factors of safety are a recognition of the additional risk that is allowed for cargo but not humans and the extreme importance of light weight.

 

            It is common for people to talk about human rating  expendable launch vehicles with a poor understanding of what that means.  Among other things, it means that the structure carrying the vast loads which rockets endure would have to be significantly redesigned to be stronger than it currently is.  In many cases, this is tantamount to starting over in the design of the vehicle.

 

            So to the hoary old punch line:  Would you want to put your life on the top of two million parts, each designed and manufactured by the lowest bidder?

Riding the Phugoid

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Phugoid, for the non-aviators, refers to a long term longitudinal oscillation in the flight path of a flying machine. More precisely it is the exchange of altitude for airspeed with constant angle of attack.  Whew, I had to look it up in my old textbooks to get it right.  One of the on-line helps says that the engineer that invented the term “phugoid” took it from the Latin but got the translation wrong.  That figures.  Most engineers don’t know that the ancient Romans studied aircraft control.

We studied phugoidal motion a lot when analyzing shuttle re-entry.  It is most pronounced on an abort entry where the shuttle’s forward motion doesn’t create enough lift until the vehicle falls into the denser part of the atmosphere and then there is too much lift so it bounces upward to where there is not enough lift and then it falls down to where the dense air creates too much lift and causes it to climb up to where there isn’t as much air where . . . .   Well, you get the picture.  Not exactly a roller coaster, but somewhat disconcerting. 

If you are designing a re-entry vehicle with any lift at all, studying the aerodynamics so that lift and drag can be applied in the proper way at the proper time is crucial.  During the early portions of the shuttle entry, phugoids are to be avoided since they can lead to high heating which is . . . not a good thing.  Actually, the shuttle flies something called equilibrium glide for most of the entry phase.  This term refers to a state where the lift generated is exactly equal to the orbital mechanics forces and gravity.  In that state, the shuttle flies at a relatively constant altitude for a fairly long period of time, all the while bleeding off the incredible kinetic energy required to orbit the earth.

This is a good time of year to talk about how to fly through life:  are you riding the phugoid or are you in equilibrium glide?  I know where I am.  Yesterday was a real emotional high when the snow dusted my home and the shuttle flew over on its way back to Florida; then there were the stressful lows — like when I tried to untangle the Christmas tree lights . . . .

My job has continued to move away from the purely technical to a place where people skills are increasingly important.  One of my “other duties as assigned” is to represent the agency from time to time with the folks in the media.   The prospect of having this kind of interaction causes a lot of people in NASA to refuse promotions . . . engineering being generally considered to be more important than talking to the public or dealing with the media.

One of the new phenomenon in media is the blossoming of the blogosphere — exactly where we are today.  The neat thing about the internet and blogs is that anyone can spread a lot of knowledge and insight to many folks in a very rapid and inexpensive way.  The sad thing about the internet and blogs is that there is so much misinformation and personal opinion passing for fact out there.  In the last few months I have become much more involved in the new media. 

Some of it makes me miss the old media.  It is sad to see reputable old style news organizations in financial trouble laying off experienced and professional journalists, for example.  And being over the age of . . .. (ahem) 30 . . . I still prefer the feel of a real newspaper in my hands toreading streaming news off a computer screen.  But, OK, things change and we all have to learn to use the new tools.

My biggest problem with blogs and the internet — and I’m far from being the first to observe this — is the continual flame wars that go on.  Seems like everything posted attracts someone with a contrary view — that’s OK, in fact, that’s a good thing — but too frequently a contrary view stated in the most vituperative and inflammatory way.   A good exchange of views can be enlightening.  A rude exchange of person insults is just depressing.  Sigh.  Makes me want to repeat the old SNL line:  “can’t we just all get along?”  

To participate in this new world of internet interaction, you have to develop a thick skin.  Recognize the valuable components of a enthusiastic exchange of ideas and ignore the ad hominem and personal attacks and general lack of civility that seems to be rampant on the web these days. 

Its hard to avoid riding the phugoid between the highs that happen because of a great and productive exchange of ideas and information, and the lows that come with depressing and inappropriate personal attacks.

So my aerospace analogy, at least for the holiday season, is to avoid the phugoid and try to stay on the equilibrium glide as long as you have the energy. 

Hey, that probably applies to family get togethers for the holidays, too!  Don’t sweat the small stuff.

 

 

Real Engineers

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I earned an undergraduate degree in engineering from a prestigious and notoriously competitive university.  After that I went on to do engineering research and complete a graduate degree in engineering from another major university with a reputation for excellence in engineering; along the way I wrote and defended a thesis and authored several papers which were published in professional engineering journals.

When I came to work for NASA, I was fortunate to get a job in the operations area:  mission control.  A thorough understanding of engineering principles and practices was mandatory for my job.

So I was floored just a few months later when I first heard it:  “you are not a real engineer”. I was just “an ops guy”.

In the NASA pantheon of heros, the highest accolade any employee can be granted is that they are a “real engineer”.  Not even astronauts rate higher.  The heart of the organization worships at the altar of engineering:  accomplishment, precision, efficiency.  What does it take to be a “real engineer”?

In the ethos and mythology of NASA, a real engineer is one who has several characteristics. 

First, they must have a superb grasp of the physics of their subject, a complete an total knowledge of the details of their specialty.  This almost goes without saying.  No nincompoops allowed; no fuzzy thinkers who are vague on the basic concepts.  A “real engineer” knows his arcane stuff forwards and backwards and from the middle out towards both ends and can recite it in his sleep.  “Let me tell you about the inviscid terms of the Navier-Stokes equation . . . ” a real engineer might say. 

Second, a “real engineer” must create something, taking it from original concept to working, functioning reality.  No view graph engineers ever get the title “real engineer”.  If it doesn’t fly or move or compute or generate power, or do some concrete something, you haven’t built something real and without building something real, you are never going to be a “real engineer.”  And the thing has to work; if it flops, then you are merely a tinkerer, not a “real engineer”.

Thirdly, “real engineers” are mild mannered; never needing to raise their voices, not loquacious, not given to long and convoluted discussions.  No, real engineers are soft spoken and terse; they are recognized by their brevity and the ability to concisely summarize a technical point in a way that admits to no further discussion.

NASA is full of “real engineers”. 

So us poor ops guys, who never had a drafting table, who never went into the machine shop to hand blueprints to a tech, who never got to blow up anything on the test stand; we failed miserably on the standard of being a “real engineer”.  We merely operated the stuff that the real engineers built.

Along the same lines . . . .

I have been privileged to watch the advanced concept boys at work.  They are marvelous.  Through the study of all past and current rockets they have developed a number of “empirical models” — rules of thumb if you will — that can help in the initial ideas about building spacecraft.  If you want to lift a certain number of metric tonnes to low earth orbit, given a particular rocket type (solid, liquid, hypergolic, cryogenic, hydrogen, kerosene, etc.) the advanced concept boys can give you a variety of options based on known ratios of structure weight to propellant weight, burn out mass, etc.  And they can give you a rough guess at the cost.  And they can evaluate multiple options and compare them one to another in very short order. 

In the summer of 2002, I got to participate in an exercise for about two months of possible design options of manned missions to Mars.  The advanced concept boys generated a new heavy lift launch vehicle about every other day and could compare all the designs against each other on a number of figures of merit.  Its heady work to invent new Saturn V class rockets in the computer lab.  Taller, shorter, with solid boosters or not, using kerosene or hydrogen or whatever.  One engine, two engines, five engines, twenty engines; two stages, three stages, four.  Whew.  At the end of two months the team had a great list of options and the pros and cons for every launcher.  And I found out that the advanced concept boys have been studying this problem for 40 years!  They have evaluated hundreds, thousands of various options.  Then they refined their studies, re-examined the basis for their methodologies and started in again. 

But you know what?  Advanced concept folks, even with all their knowledge of engineering principles, they are not “real engineers”. 

Real engineering starts after the viewgraphs stop.  Real engineers take the concept — boiled down as it may have been from hundreds of starting options — they take the concept and start making it real.  When you have to really design and build the rocket in its detailed glory; when you have to take the subsystems out to the test stand and start them up and see if they hang together; when you go from weight estimates to actual plans and find out what the gizmo really does weigh — that is real engineering. 

That is where you find out if the concept really will work or not; what the real problems are and how to solve them. 

When the rocket really flies you have proof positive of the real stuff of engineering — and whether you have it or not.

That is what real engineering is all about.