[SS-VehDev] NC Matrix

[william colburn]

Great, exactly what I was hoping for. First, from my
previous post, this was for concept only. What concept
would be best for the project. Secondly, it is a
combination of intuitive engineering judgement and
years of experience partly with NC's.

I did include comments which will show on any xls post
95.

This is not a matrix which would specify a specific
design. As it shows, the concept is not important,
they all scored about the same. It is the design which
will prove to be workable. For composites, yes that
would have to include an ablative tip or a metal tip.
For Titanium that would have to include interior
insulation.

For all the design would have to include means of
supporting electronics. For carbon composites and
Titanium, means of getting RF out of the NC would have
to be made.

So the matrix just said: "you can make the NC out of
any of these materials, but you will have to do a
great deal of design work to adapt each to its
function". 

As for the thermal environment, at the end of the
first phase, the vehicle is at about 7000 ft and its
velocity is about M1.5. No problem with heating for
the concepts we are looking at. It does not reach M5
until 50,000 feet. There the pressure is 3.5 psi and
the temperature is -70 F (t1 in most stagnation temp
equations) so although the temp will be high, the
duration will be short. Only a more stringent sim will
tell us the complete temp profile. It is not important
 for the choice of the method of construction since
all of the above have some history for short exposures
to M5 (but with ablative protection in the case of the
straight glass/epoxy cconstruction)

The "concept 4" you mentioned would be the design
additions necessary to make 2 or 3 work.

We have to supply the Titanium which is why cost is a
factor in the Ti NC.

The exact design awaits some detailed sims.

Hope these explanations cover most of your well made
points.

The matrix was also made to be used by others. With
only "concept" as a criterion, I wonder how your
particular matrix would have come out based on your
own experience and research? I actually fudged on the
last column which is to be based on the group's
inputs.
Shame on me.

BC


--- Lakestake Rocketry <lakestake at gmail.com> wrote:

> OK Bill, you asked for comments... These are not
> warranted to be
> on target, but hopefully they can stimulate some
> converstaion.
> 
> What are the environments requirements/limitations
> of our nosecone
> mounted instrumentation? I suggest we be more
> specific here.
> What are the acceptable temperature, vibration and
> 'gee' extremes?
> For these numbers I think we can specify something
> standard and
> have the payload team get back to us if they have
> something more
> delicate in mind.
> 
> You mention a 100fps impact of the airframe, what
> impact force will
> this translate to for the instruments after
> insulation by the airframe
> and payload bay? What shock/vibration/heat
> insulation does the
> design then need to deliver?
> 
> Is 10 seconds enough for the heat time? I agree that
> the burn will
> be short, but we may still be heating (or at least
> not cooling) for the
> first part of our initial coast while we are still
> in some atmosphere.
> 
> As we may be talking about composites on the nose,
> fins or airframe
> 'too hot' may be lower than the 1000' you have
> specified. Do we have
> any sounding rocket heating data to work from? It
> would be interesting
> to have an idea what environment we will be facing.
> 
> What about adding a Concept 4 to the matrix. It
> would be a hybrid NC
> formed from a composite cone with wither a metal tip
> or metal sheathing.
> We might be able to get the best of both worlds.
> 
> Do you have definitions for each of the columns? I
> think many are
> self-explanitory, but as we are dealing with an
> international team it
> might be good to jot down a quick sentence or two
> about what you
> are intending.
> 
> I am not sure on what basis the numbers in the
> columns 'Legacy',
> 'Engineering Evaluation' and 'In/Out' are generated.
> 
> Could a short list of the factors that weighed into
> each number be included
> with the matrix? This would allow other team members
> to understand and
> contribute to how the numbers are derived.
> 
> I notice a two in the availability column for
> Titanium. Isn't this already 
> handled
> by our vendor? If so shouldn't this number be higher
> as this is no longer an
> impediment to selecting that design? I agree that
> Carbon is harder to find,
> but there are many good sources in LA, I have never
> had a problem getting
> just about any grade on a moment's notice. My
> suggestion, lacking your
> insight as to what other factors went into the
> numbers, is that the 
> availability
> values should be 4 across the board.
> 
> Hope these thoughts help. Anyone else have ideas?
> That's what we are on
> the team for!
> 
> Matt
> 
> On 9/8/05, william colburn
> <space1space at sbcglobal.net> wrote:
> > 
> > The matrix gives about the same score for all
> > candidates. Since it is probably about +/- .5 or
> so,
> > the values are really the same.
> > 
> > I am rather in favor of Andrej's composite-over-
> > honeycomb version. It comes out about even with
> the
> > others and even better if he uses carbon composite
> > too.
> > 
> > The idea of adding the attachment points for
> > instruments and hardware as nutserts is appealing
> too.
> > 
> > The Titanium is the high tech version and would be
> > free to us. It suffers from needing insulation for
> the
> > inner workings.
> > 
> > Comments?
> > 
> > BC
> > 
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