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UPDATE #26 - June 26, 1998

PART 1: New Careers Section
PART 2: Helicopter Blade Tracking
PART 3: Subscribing & Unsubscribing: How to do it


NEW CAREERS SECTION

Announcing a new background section for Aerospace Team Online:
Careers in Aeronautics.  This new addition was written by Ernest
Aguayo, and describes different career options and gives suggestions
for educational preparation.

http://quest.arc.nasa.gov/aero/background/careers/

[Editor's Note: Brent Wellman is a Project Manager developing software to analyze helicopters on computers at Ames Research Center. Read his bio at http://quest.arc.nasa.gov/aero/team/wellman.html ]

HELICOPTER BLADE TRACKING

Brent Wellman

June 2, 1998

First thing this morning I printed out a letter I composed yesterday.
The printer is not busy at 6:30 and I need to use special letterhead and
watermarked paper. The letter is to a witness to a recent mishap here, and
I am chairman of the investigation board. The letter has to look nice and
professional. The committee won't meet again for a few more days, but I
have to do my homework.

Sometimes it seems like I do homework for a living...

After mailing off the letter, I settled in to evaluate a technical
proposal from a small company. I won't say much about it, because it
involved trade secrets and all, but it involves blade tracking in
helicopters.

Blade tracking? What's that? You say. Helicopters get lift from their
rotor blades. They seem like very flimsy items to be holding up an
aircraft, when you see one sitting on the ramp, but they get very stiff
when you spin them around. If the blades generate lift, they tend to rise
upward; centrifugal force, on the other hand, tends to keep them flat.
When these two forces are in balance, the blade flies at a shallow angle
above the horizontal.

The rotor traces out a shallow cone, and the rotor is said to be "coning."
This coning angle varies with the lift (the centrifugal force is nearly
constant), and can be observed if you watch the spinning rotor from the
side as a helicopter lifts off. Anyhow, even the most finely crafted rotor
blades show slight differences in shape and form that result in small
differences in the lift they generate. Therefore, the angle may vary from
blade to blade, and the blade tips will not fly at the same height. Such a
rotor is said to be "out of track," and the ride gets very rough. The
exact lift on each rotor blade is adjustable, and the process of getting
the blades to fly in line is called "tracking."

This company has a bright idea about how this may be done more easily, but
I can say no more. I finish my appraisal, and return the proposal to the
researcher in charge of the effort.

Next, I am called into a meeting with the branch chief and his deputy.
Performance plans will soon be drawn up, and they solicit my input as to
how people's performance plans can be made to mesh with program goals. We
also discuss increasing the duties of one staff member and adding another
to the group. I make some notes on action items for the next few weeks and
leave.

I need to think about my goals for next year as well.

I do a bit of office tidying; I recently moved into a cubicle in another
building to allow for remodeling, and much got scrambled in the move. I
devote a few minutes each day to organize the new office.

That done, I took a break to read the forward of "The Third Culture," a
book of essays on scientific thought that I am starting to absorb in my
spare moments.

I then scanned a paper from the last American Helicopter Society forum.
The paper will be synopsized in a lecture this Thursday, and I want to be
up to speed beforehand. The paper is especially important in that it
assesses the limitations of comprehensive codes. The author compares
2GCHAS to flight test and to, well, let's just say "Brand X" comprehensive
code.

Time for lunch...

I'm back. A quick check of my email and messages, and I'm back to work.
The 2GCHAS Project Office has gone through some changes recently, and I
must work up vision and mission statements for the group. Of course this
requires input from the troops and a buy-in from management. To date,
nobody agrees fully, but we're basically in the same ball park. I just
have to coordinate it, figure out what is truly important, and make some
hard choices.

Piece o' cake!

I spend a bit of time dressing up a presentation on the vision/mission on
the computer then put it to rest. I don't generally go after the big
problems in a single leap.
I worked on some computer system issues with the resident computer guru.
2GCHAS has several computer systems to duplicate the computer systems our
customers run on. We need to be sure 2GCHAS will compile link and run, and
we need to assess how well problems "converge" on the various systems.
They
ought to run the same way on all, but don't always do that.

Anyway, there were some security issues to clear up (gotta keep the
hackers away!), which I did, leaving me with enough time to finish my
journal for Aerospace Team Online.

Time to go home!

SUBSCRIBING AND UNSUBSCRIBING

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