[SS-VehDev] Re: casing

[william colburn]

Generally; but I think that Rich should bring motor
discussions to the group directly and as a co-leader
should bring whatever he feels important to discuss to
the group at large. I will bring items of interest to
the vehicle design group specifically and also to the
group at large when it is of general interest.

I was involved in the grit of the case composite
question. It could have been brought up with the
larger group earlier or later as I see it, so long as
it was shared at some point. That actually is the
purpose of having separate groups so the mailing list
does not get bogged down with rehashing of already
determined or decided design features or directions. 
(already happening, incidently)And the reporting of
the groups to the list is that communication we all
desire. For instance, I don't want to be involved in
the slightest in choosing a patch, helix, dipole,
dielectric slot or any other antenna for the vehicle.
I prefer not to be in those discussions. I do want to
hear the report after the decision has been made,
however.

Where I or others have special expertise, we would be
missing the point of the group effort not to
contribute in those specific areas.

I apologize for the length of my reply. It clears some
of the points I wanted to make.

BC  

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

> Richard,
> 
> I think Bill is the right person, as head of the
> VehDev group, to open
> this discussion up to the group when he feels that
> either:
> a) we have reached a proposed design ready for group
> presentation
> b) we have reached a point where we need more group
> input
> 
> Bill, do you concur with these two statements?
> Richard, does this fit with your understanding of
> 'group procedure'?
> 
> Richard, my suggestion is that you put together a
> 'topic starter' email
> letter including your take on what specific
> questions we should open
> up for group comment and forward that to Bill for
> revision and posting
> as he sees fit.
> 
> Bill, I agree with Richard, we could gain a lot from
> the experience
> the group brings to the table. As with everything on
> the Internet we
> will have to separate the wheat from the chaff...
> 
> Matt C
> 
> On 10/3/05, Richard Nakka
> <richard.nakka at aero.bombardier.com> wrote:
> >
> > Gents,
> > Why don't we discuss this side-study on the
> ss-main list?
> > It'd be a good way to help re-establish interest &
> communication in the
> > SStS Project?! We've been sadly failing in this
> regard, in my opinion.
> >
> > Richard
> > -------
> >
> >
> > william colburn wrote:
> > >
> > > Matt,
> > >
> > > We can propose a mandrel diameter. We won't know
> the
> > > actual wall thickness we will ultimately require
> until
> > > be do more testing.
> > >
> > > The nozzle is being made with an OD of 9.873
> +.005
> > > -.005 inches. 9.881 would be the OD of the
> mandrel
> > > assuming a minimum clearance of .003 inch for
> "O" ring
> > > and a slip fit. With a tolerance stack-up we
> could end
> > > up with a diametral clearence of .013.
> > >
> > > At a level of 41KSI, the tubing fabricator (who
> has
> > > not yet quoted!) is using a wall thickness of
> .188.
> > > The materials are E-glass and epoxy.
> > >
> > > Even with hand-layup, we should be able to match
> that
> > > tensile yield number. This means that our wall
> > > thickness will be in the same ball-park as .188.
> > >
> > > If so, we are in-like-Flynn. If not, then no-go
> as the
> > > casing weight will be too great for making our
> mass
> > > ratio.
> > >
> > > So with a relatively simple experiment, we will
> know
> > > if we can hand-layup our own casing.
> > >
> > > If we are successful in hydro, this sample or
> one like
> > > it could be used for the short-stack test.
> > >
> > > BC
> > >
> > > --- Lakestake Rocketry <lakestake at gmail.com>
> wrote:
> > >
> > > > Hi Bill,
> > > >
> > > > I was getting ready to acquire the mandrel, I
> wanted
> > > > to get your
> > > > feedback/requirements soon so I could move
> forward
> > > > on it. If the SS2S
> > > > project does not have a hard size requirement
> I can
> > > > make the other
> > > > project to spec. If that won't work for us I
> can
> > > > work on changing the
> > > > other spec to match SS2S. I just need to know
> which
> > > > way to jump.
> > > >
> > > > The current M-100B design calls for a 250mm
> O.D.
> > > >
> > > > I understand and can follow your approach
> below, but
> > > > I don't want
> > > > to change the other project to adhere to SS2S
> > > > requirements unless
> > > > it has been determined that this is the way
> SS2S
> > > > will be going. It
> > > > does not make sense to purchase one mandrel
> for
> > > > testing, then
> > > > another for the final project.
> > > >
> > > > I see Richard has posted a follow up, more
> comments
> > > > once I have
> > > > read that.
> > > >
> > > > Matt C
> > > >
> > > > On 10/1/05, william colburn
> > > > <space1space at sbcglobal.net> wrote:
> > > > >
> > > > > So the mandrel is 250 mm? Or is the finished
> part
> > > > 250
> > > > > mm OD?
> > > > >
> > > > > Here is a plan:
> > > > >
> > > > > Use your existing mandrel to make a short
> stack
> > > > casing
> > > > > to best procedure using carbon fiber,
> kevlar,
> > > > glass
> > > > > where appropriate.
> > > > >
> > > > > We will develop end closures and hydrotest
> the
> > > > sample.
> > > > >
> > > > > From there we will make a decision to go
> forward
> > > > or
> > > > > move to another casing source.
> > > > >
> > > > > We can talk about the exact procedure when
> you are
> > > > > ready to go. It would likely involve an
> initial
> > > > room
> > > > > temperature cure with shrink wrap, removal
> of the
> > > > > shrink wrap followed by a two stage cure at
> > > > increasing
> > > > > temperatures.
> > > > >
> > > > > No gel coat, it adds weight and no increase
> in
> > > > > strength. No sanding, weakens the outer
> layre
> > > > which
> > > > > them becomes dead weight also.
> > > > >
> > > > > BC
> > > > >
> > > > > --- Lakestake Rocketry <lakestake at gmail.com>
> > > > wrote:
> > > > >
> > > > > > Hi Bill,
> > > > > >
> > > > > > The M-100B has a 250mm airframe. It
> doesn't
> > > > really
> > > > > > *need* to
> > > > > > be 100% scale, but it would be nice. I can
> fudge
> > > > > > either project to
> > > > > > match the other as needed. I would need to
> know
> > > > soon
> > > > > > though...
> > > > > >
> 
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