Subject: Re: X-33 info....help!!
From: rob.wingate@msfc.nasa.gov (Rob Wingate)
Date: 9 Nov 1996 18:21:47 GMT
In article <55tu2v$923@csun1.csun.edu>, hbmen026@huey.csun.edu (manuel
magrane) wrote:
> Hello,
> I am an engineering student at CSUN, and I am writing a
> paper on the DC-X/DC-XA/X-33 reusable rocket prototype, more specifically
> on the materials (Al-Li alloy). Does anybody know of any references
> whether it be on the internet, books, or magazines I can be pin-pointed
> to? I have tried several periodical resources, but they are too skimpy
> when it
> comes down to specifics. Any information is appreciated! Personal email is
> preferred.
>
The DC-XA & X-33 are part of the Reusable Launch Vehicle Technology
Program managed by the NASA Marshall Space Flight Center in Huntsville,
Ala. Generic information can be found at http://rlv.msfc.nasa.gov.
Al-Li is also being used on the Super Lightweight Tank Program, also
managed by the Marshall Space Flight Center. Some info can be found at
http://www.lmco.com/manned/slwtank.html
http://jefferson.vf.mmc.com/lmtoday/0296/tank.html
Rob Wingate
Subject: Re: Egg drop mechanism
From: dave lawson <71202.1577@compuserve.com>
Date: Sat, 09 Nov 1996 14:39:55 -0800
mchalefla@worldnet.att.net wrote:
>
> Let's clarify something, Alan Gideon, Tom Austin and Thomas Wynsen...
>
> Who do you punks think that you are, criticizing me in such a way?
> Perhaps it's because I am new to USENET that I have taken offense to the
> replies to my simple query. Or perhaps it's because I take any
> criticims of my own intelligence very seriously. However, if you wish
> to preach to me the importance of doing this project on my own, then you
> obviously do not wish to offer advice, which is all that I asked of you.
> Did I ask for a sermon on the benefits of doing my homework myself? I
> think not. Next time, don't waste your typing time or my reading time
> for your useless and pointless comments.
>
> Kevin
Kevin,
IMHO, you have probably just pissed off the very people that CAN help
you. We have virtually all 'been there', 'done that' and many of us
'got the t-shirt'. If you are interested simply in getting good marks,
most of us here are probably not all that interested in helping.
If you are offended by the opinions of others, you should not ask for
them. If you simply want a direct answer to your problem, go find a
consulting engineering firm and pay for it.
If you had perservered and asked questions that indicated that you had
actually thought through some of the principles (ie. "I know that I need
to slow the egg down slowly, but I don't know how to figure out the
amount of foam rubber needed to do it, or if there might be a better
material", etc)then people WILL jump right in and offer ideas. I have
seen some relatively simple requests for information turn into very long
threads with an enormous amount of really usefull information being
posted.
Dave Lawson
Aerospace Engineering Punk
Subject: Re: Fighting Complexity
From: peb@transcontech.co.uk ("Paul E. Bennett")
Date: Thu, 07 Nov 96 10:18:16 GMT
In article
jamcorp@world.std.com "Jonathan Priluck" writes:
>
> Hello (good morning?),
>
> It's 4:00 am and I can't sleep becuase this new injection mold
> we're desiging is driving me nuts. It's not the mold per se so much as the
> management of the project and a sudden recognition that I keep running into
> a very similar problem in many different areas of our development effort (on
> automation of LBM manufacturing). In a nutshell, there seems to be a
> tendency on the part of almost everyone I'm managing and working with to
> move quickly past simple solutions in a hurry to try implementing more
> complex options.
[%X]
> ......................... But that is not the real issue, and that's what
> I wanted to talk about in the first place. The real issue is that nobody
> seems to want to *try* the simple solution first. What I want to know is why
> that is?
It's just because they are simple that they are bypassed. Almost everyone
likes to try-out the more complex model first. If it doesn't work they may
get back to the simple model later. I agree this all wastes time and money.
How do you break that?.
One way you could try it is to set up three teams of designers. They each
come up with a design and a method for implementing it and rough budget
costings. Each team presents their design and the other two have to find
fault with it. The design that wins out is the one with the least problems
and least cost. The one who goes first is the one with the lowest bid
costings. Costings have to be revised up for each problem that is found. If
you find that another team, presenting before you do, has had the same idea
as yours you still have to pick the holes in it. Then choose another idea.
One last item. Set a very tight time limit (hours not days) so that they
don't get too long to think.
It's a good game and may just get them to think differently about their
design chooice methods.
I have been in only one place where this practice went on for one project. We
ended with a really elegant and simple design that really was very cost
effective. Which of the three designs did we eventually select?. .. None of
them. In the process of shredding the other teams ideas we all began to
realise that all the original design ideas had problems and in resolving
answers to each of those we found a totally new solution that none of the
teams had come up with.
--
Paul E. Bennett
Transport Control Technology Ltd.
+44 (0)117-9499861
Going Forth Safely
Subject: Re: Fighting Complexity
From: jamcorp@world.std.com (Jonathan Priluck)
Date: Sat, 9 Nov 1996 21:45:38 GMT
>Jonathan,
>
>You seem to have a management problem on your hands. It would
>appear that your designers are in extreme local optimization mode.
Tony,
I really appreciate your help. Most of what you've outlined is
essentialy correct, except for the details which (as you've noted) you have
no way of knowing. The methods and techniques you suggest are a good
starting point and a great way to begin learning the art of sound
management. Naturally I do not tell the people involved that they are wrong,
nor do I typically arouse their resentment over such issues. The art of
persuasion is more delicate than that and I've a good deal of practice at it
over the last 15 years. The investment in the total organization takes
precedence over regional conflicts associated with particular projects.
Building respect amongst the team members is more important than how
these particular molds turn out and we've a pretty solid foundation already
in place. The people I am working with who are part of our team are
exceptionally talented and I have to trust their instincts in 90% of all
circumstances. In the remaining 10% of situations where the teams skills,
talents, and knowledge are not enough to acheive the objectives we've set, it
falls on me to lead by example. Often I have to lead even though I do not
neccesarily know where to go either. And even as I forge ahead I am
counting on their skills to peice together something workable out of the
initial direction I can sometimes provide.
>It might be useful to remind them that the objective is not to
>have the best possible mold but to bring a good-quality product
>to market as soon as possible?
>
>You might also consider communicating with them by using Goldratt's
>"cloud," also known as a conflict resolution diagram. I'll take a
>stab at creating one for you. But you'll have to improve it, to
>make it valid for them and for yourself.
Let me tell you a story. I had a summer student in here this year
with whom I was unable to establish a good rapport, I was not able to
establish with this young man the level of communication that we require of
people who can fit in on our team, who can be part of our organization. His
problem stemmed from his initial expereinces in the work force and in the
techniques he had learned to overcome them. His earliest work expereince
was in an enviroment very similar to yours where fundamental tools are needed
to establish the most basic level of edequate communication. These tools are
detailed and sophisticated, they help you break down a situation and deal
with the hidden assumptions one at a time as they are systematically
uncovered. This young man had seen these principles applied at his former
place of work and was duly impressed with the results. When he came to us
and saw that we were not using these tools he immediately set to work
educating to educate us as to how to use these wonderful techniques. He
became very frustrated when nobody seemed to understand him and ultimately
left in frustration. He was never able to assimilate, and the reason why
will probably never be clear to him though it was painfully obvious to
everyone else. He had assumed we had a communications problem similar to
the one he had expereinced before. What he could not see was that what he
considered to be the pinnacle of effective communications was actually *far
below our minimum standards*. This is not a new phenomenon, there is a
saying in the Torah (Old Testament) which translates roughly as "a penny
rattles loudly in an empty jar".
It has been my personal observation that many of the engineers who step
into management have a tendency to assume that they are stepping in at the
highest levels of sophistication. Those I have known assumed that becuase
a concept is new and difficult for them to assimilate, it must be equally so
for everyone else too. As my father likes to say, "welcome to America Mr.
Columbus:^)
> (B your need) (D your want)
> bring the product to accept a mold that makes
> market quickly. slightly oval shapes.
>
> (A objective)
>have a financially
>successful product.
>
> (C their need) (D' their want)
> have a good-quality have a mold that makes
> product. circular shapes.
This is a management tool. I don't want to use it becuase to do so would
insult the people I am working with and undermine the foundation we have
built. These people are capable of managing themselvs and know when to ask
for assitance. Treating them like kindergardeners is not going to improve
matters.
>When you communicate with them, try to follow the script, below.
I am not their teacher. These are colleuges and freinds. The concepts
involved in the scripted dialog are completely correct but the notion of a
scripted dialog is by it's very nature contrary to those same principles.
>It's a good idea to role-play it with a neutral party first, even
>if that neutral party is your own image in a mirror.
>
> "First, do we agree that our common objective is to have a
>financially successful product?"
> They are very likely to agree with this statement.
Playing games with people is not a legitimate way of building trust within
an organization. Most people will not agree, or will do so grudginly becase
they will immediately sense an alterior motive. More often people will
pretend to agree so that you will finish and go away. People are not stupid,
simple techniques are useful to illustrate a point but you practice them at
your own peril. People will typically smile and nod, once you leave they
will go right back to whatever it was they were doing before.
Best Regards Jon Priluck
--
* Jonathan Aerospace Materials Corp., 37 Antwerp St. Brighton MA, 02135 *
* Tel (617) 783-4588, Internet: president@jamcorp.com *
* Developers and manufacturers of Lattice Block Materials ... *
* the world's strongest and lightest materials. *
Subject: Re: solder accelerated ageing
From: Peter Swanson
Date: Fri, 08 Nov 96 15:35:09 GMT
In article <55q7ah$git@news.u-bordeaux.fr>
thebaud@ixl.u-bordeaux.fr
"Jean-Marc Thebaud (Resp. C. Zardini" writes:
> I am looking for information about solder accelerated ageing, but I would
> like an answer from the mechanics point of view. If you cannot answer the
> following questions, please give me references which could help me :
>
> * what comparision can be made between two identical samples (that is
> same geometry and same alloy composition) which have undergone two
> different thermal loadings but whose stress-strain hysteresis curves
> have the same area?
>
> * in particular, can we assess that these two samples are at the
> same state of their lifetime and at the same degree of fatigue?
The SMART Group has a conference next week in Brighton, England. One of the
papers is by Rob Wallach of Cambridge University, entitled "Predicting Solder
Joint Reliability". I am sure that other work has been done by the National
Physics Laboratory (try Dr Colin Lea as a contact) and University of
Loughborough (try Dr David Whalley as a contact).
Many of these sources may be contacted through The SMART Group at
http://www.smtuk.demon.co.uk.
Peter
--
...............................................................................
Peter Swanson Oxfordshire, England
peter@cygnetuk.demon.co.uk Compuserve: 100120,3641
http://ourworld.compuserve.com/homepages/Peter_Swanson
Confidence is the feeling you have before you understand the situation.
...............................................................................
Subject: Bearing choice, wet, low! friction
From: Svein Medhaug
Date: Sat, 09 Nov 1996 03:58:24 +0100
I'm writing this request on behalf of a, yet, small company, manufacturers of
light machinery. I'm not very much into machinery myself, so please have me
excused if technical terms are inaccurate.
They are looking for the best bearing solution for a newly developed device. Plan on a
large scale production, and want advices on optimising price/performance relationship.
BEARING DESCRIPTION:
On the proto-type there have been used stainless steel 6003 2RS bearings, which have
been found to serve the *purpose* good, but a little costy.
They will run in tap water, low level of particles.
Radial force max 10-15 kgs.(20-30 pounds)
Axial force max 3-4 kgs.(6-8 pounds)
Forces may vary from 0 to max every second (not very "impact".).
Running time averages only 5-10 mins/ day.
50-150 RPM
Drive force is low, so not very much static friction allowed.
1. They would like know if anyone can recommend any *alternative*, cost-effective
bearing types???
(New materials/solutions welcome.)
2. A recommendation and/or qoute, price/bearing "can" be posted to me.
Or I may put you in contact with the right persons, for more details.
Amount: Need for first series will be approx. 20 000 pc bearings.
Please mail me at: smedhaug@sn.no
Regards,
- Svein Medhaug
Subject: composite wings
From: ba501@city.ac.uk (Eslimy-Isfahany SHR)
Date: 10 Nov 1996 19:42:29 GMT
Dear colleagues,
I am a phd student in aeronautics. I am interested in the dynamic response
of aircraft wings specially those made of composite materials.
Currently, I need a set of date of mechanical properties, i.e.
flexural and torsional rigidities and etc., of an aircraft wing and/or
helicopter or wind turbine blades made of composite materials.
I would appreciate it if you could help me out.
Moreover, I am looking for other people or institute with similar interest
to share some experiences and possible collaborations.
I look forward to hearing from you.
Thanks
Hamid
Subject: Re: Ignitioning Yourself
From: "Lawrence S. Galt"
Date: Sun, 10 Nov 1996 20:53:20 -0800
Damage from electricity results from electrons flowing through an object
and temporaraly or perminately altering it. This flow is called
electrical current and is measured in amperes.
Electrons like water current must have some pressure difference between
their present location and where they are going in order to make them
flow. This electrical pressure is measured in volts.
The 3rd element to consider is how good of a path there is for the
electrons to get where they are going. A good path is a good conductor
while a poor one is an insulator.
A wire is a conductor and the coating around it which offers a large
amount of resistance to current flow is an insulator.
The human body is usually a poor path (i.e., bad conductor) so it takes
a lot of pressure to cause electrical much current to flow. It is very
unlikely that you would even feel the current produced by a car battery
with apx 14 volts of pressure across your body. However, the resistance
to current flow of the human body depends on many factors.
To insure our safety the conductors (wires) in electrical circuits are
surrounded with insulators that have a very very high resistance to
electrical flow. The wiring, switches, connectors, etc. in a car are
covered with insulators to keep you from coming into contact with the
conductors. Therefor you have a poor path for the current to flow
between the ignition switch and the key.
--
Larry Galt - - - - A Right Wing South-Paw - - - - lgalt@multiverse.com
When the world thinks right & works left, all thats left will be right!
UNTIL THEN - KEEP YOUR POWDER DRY!
Subject: Re: Coefficients of Friction for Tire on Roadway
From: Doug Milliken
Date: Sun, 10 Nov 1996 05:55:13 GMT
On Fri, 8 Nov 1996, jason graklanoff wrote:
> I am looking for static and kinetic coefficients of friction for
> automotive/truck tires on dry, wet, and dirty roadways. Need not be specific
> to any particular tire model; typical numbers are just fine. Can anyone help
> me out?
An important thing to know is that the coefficient (mu) is dependent on
load. At light loads (100 lbs, 450N) an ordinary passenger car tire might
be capable of a mu>1.0, but at high loads (2000 lbs, 9000N) this might
degrade to mu<0.6 or so. This is on a good surface, on an old polished
surface (like a well worn intersection) it will probably be less.
As long as it's dry, the peak mu is not much different from the sliding
mu, for most of the tires we've seen data on (again, on a good surface).
Since truck tires are designed for long wear, the rubber is "harder"
and may give a lower mu. "Harder" does not necessarily imply higher
durometer readings -- rubber chemistry is complex.
Performance tires (and race tires) are just the opposite. We have seen lab
tests where mu>2.0 (at light loads)! In this case the rubber is sort of
"sticky" to the touch, and material is transferred from the tire to the
roadway - there must be adhesion between the tire and the road surface,
much different than classical "coefficient of friction".
Sincerely,
-- Doug
Douglas Milliken
Milliken Research Associates Inc.