[SS-VehDev] Re: [SS-Main] new Propellant Team member

Fri Oct 7 10:28:01 PDT 2005

Hi Richard,

I'm out of town now, I'll double check the BC when I get back on Sunday.

Matt

On 10/7/05, Rich Nakka <richnakka at rogers.com> wrote:
>
> Lakestake Rocketry wrote:
>
> Hi Richard,
>
> Here is a really gross simulation, just a big dumb rocket without lugs,
> with buttons, and with tubular lugs.
>
> This is simulated with Aerotech's N4800 Blue Thunder composite
> motor. Let me know when thrustcurves.org <http://thrustcurves.org> has the
> SS2S motor
> definition file available for download.
>
> The first two runs were with lugs, the second buttons, the third tower.
>
> The difference in altitude was 0.25%. Not a lot, but when we are
> trying our darndest for that last 1000 feet it adds up.
>
> Let me know what else you want to see.
>
> I'll take a look and let you know. As a first shot, it is only important
> to match the ballistic coefficient (rocket mass divided by frontal area).
> For the SStS rocket, the coefficient is 13.8 lb/in^2. Use any rocket
> config that 'll give you this.
>
>
> The difference in altitude was 0.25%. Not a lot, but when we are
> trying our darndest for that last 1000 feet it adds up.
>
> I disagree. You don't want to add complexity unless it is clearly
> justified.
>
> Richard
>
>
>
> Matt C
>
> On 10/6/05, Rich Nakka <richnakka at rogers.com> wrote:
> >
> > Lakestake Rocketry wrote:
> >
> > Hi Rich,
> >
> > Do you have RS8? If not I can retype the details from the simulation.
> > I do not know how much I believe RS8's simulation. There are a lot
> > of people who swear by it, but I am always a little worried by the
> > numbers it turns out.
> >
> > Matt
> >
> >  HI Matt,
> > I tend to be a "doubting Thomas" or perhaps "I'm from Idaho" ...but like
> > you, I tend to be a healthy skeptic.
> >
> > As such, I'd like to see both the input data & the results. No, I do not
> > have rocksim.
> >
> > Thanks!
> > Richard
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > P.S. I am leaving this afternoon for a Saturday launch down here,
> > I can get to this on Sunday if you need me to retype.
> >
> > On 10/5/05, Rich Nakka <richnakka at rogers.com > wrote:
> > >
> > > Lakestake Rocketry wrote:
> > >
> > > Hi Richard,
> > >
> > > A quick simulation at lower altitudes shows that tubular launch lugs
> > > are a major source of drag. A 'T' type lug is better, but no lug makes
> > > quite a difference. These data from RS8.
> > >
> > > Matt C
> > >
> > > Matt, Please send me the details of the sims, I'm interested in
> > > reviewing it.
> > >
> > > Richard
> > >
> > >
> > > On 10/5/05, Rich Nakka <richnakka at rogers.com > wrote:
> > > >
> > > > Miraglia wrote:
> > > >
> > > > Dear Rich
> > > >
> > > > I am in favor of the solution " lugless "
> > > >
> > > > The problem will be with the project of the launch ramp.
> > > >
> > > > cheers
> > > >
> > > > Miraglia
> > > >
> > > >  Lugless should certainly be considered, but should be chosen only
> > > > if justified. The complexities of the launch tower design & fabrication
> > > > would presumably be that much greater, and I would expect failure risk would
> > > > increase too (isn't this so, Matthew?).
> > > > A drag study should be conducted to compare the vehicle with/without
> > > > lugs.
> > > >
> > > > Richard
> > > >
> > > >
> > > >
> > > >    ----- Original Message -----
> > > >   From: Rich Nakka
> > > >   To: miragli at terra.com.br
> > > >
> > > >
> > > >
> > > >   Cc: Sugar Shot
> > > >   Sent: Monday, October 03, 2005 11:16 PM
> > > >   Subject: Re: [SS-Main] new Propellant Team member
> > > >
> > > >
> > > > By the way, Jose, I forgot to mention that you should sign up to the Sugar Shot to Space e-mail discussion forum:
> > > >
> > > >
> > > > http://www.exrocketry.net/mailman/listinfo/ss-main
> > > >
> > > >   to keep up with the latest developments.
> > > >
> > > >
> > > >
> > > >
> > > >   cheers
> > > >   Richard
> > > >   ---
> > > >
> > > >
> > > >   william colburn wrote:
> > > >
> > > > Jose,
> > > >
> > > > I second Rich's welcome.
> > > >
> > > > The vehicle as it stand now will have either a
> > > > straight 5.5 aspect ratio conical NC or a 3/4 Power NC
> > > >
> > > >
> > > >
> > > > of the same aspect ratio.
> > > >
> > > > The fins are not designed. We want a minimum area both
> > > > frontal and surface of course. They must be designed
> > > > to be rigid against the tendency to flutter at any
> > > > Mach number and altitude we experience.
> > > >
> > > >
> > > >
> > > >
> > > > Rich can provide a detailed Velocity vs Altitude and
> > > > also impact pressure estimate.
> > > >
> > > > The vehicle is unique in that in incorporates a coast
> > > > period before lighting up the second burn. This
> > > > reduces the drag integral allowing more effective use
> > > >
> > > >
> > > >
> > > > of the onboard propellant.
> > > >
> > > > We can provide cartoons at this point of general
> > > > layout we anticipate, an intitial estimate of the fin
> > > > shape and size, and the two NC shapes.
> > > >
> > > > Will that be enough for you to initiate a CFD analysis
> > > >
> > > >
> > > >
> > > > of the worst case condition?
> > > >
> > > > BC
> > > >
> > > > --- Rich Nakka <richnakka at rogers.com> <richnakka at rogers.com> wrote:
> > > >
> > > >
> > > >
> > > >
> > > >   José,
> > > > Thanks again for your offer,  and welcome to the
> > > > Project's  " Propellant
> > > > Development Team " .
> > > >
> > > > With regard to CFD, I think it'd be a great idea to
> > > > model our vehicle
> > > >
> > > > using CFD to get a better indication of drag,  which
> > > >
> > > >
> > > > could allow us to
> > > > refine our simulations. Bill Colburn
> > > > (
> > > > space1space at sbcglobal.net) is the
> > > >
> > > >
> > > > Vehicle Development Team Lead and he can fill you in
> > > > on details. I
> > > > should point out that the vehicle is not defined
> > > > yet, I believe the
> > > > nosecone and fins are being studied...BC could
> > > >
> > > > provide more up-to-date
> > > >
> > > >
> > > > details.
> > > >
> > > > I think a CFD model of the vehicle on our website
> > > > would look awesome ;-)
> > > >
> > > > Something that might be studied is the effect of
> > > > launch lugs on vehicle
> > > > drag? This would be of aid to the Launch Support
> > > >
> > > >
> > > >
> > > > Team, who are
> > > > particularly keen on knowing whether or not we
> > > > should go "lugless".
> > > >
> > > > Richard
> > > >
> > > > -------------------------------
> > > > Dear Richard
> > > >
> > > > Thank you for its fast answer.
> > > >
> > > >
> > > >
> > > >
> > > > I would like to participate of the project " Sugar
> > > > Shot to Space ".
> > > >
> > > > I am chemical engineer, master degree in rocket
> > > > propulsion and
> > > > university teacher.
> > > >
> > > > Now I am coordinating a team for the development of
> > > >
> > > >
> > > >
> > > > a liquid propellant
> > > > rocket engine (H2O2/Ethanol) for the project
> > > > SARA.  http://www.iae.cta.br/sara.htm
> > > >
> > > >
> > > >
> > > >
> > > > I is also specialist in CFD.
> > > >
> > > > Already 20 years ago I develop amateur rocket
> > > > propellants. I use NaNO3 +
> > > > Sugar.
> > > >
> > > > I obtained excellent results.
> > > >
> > > > Rocket propulsion is my life.
> > > >
> > > >
> > > >
> > > >
> > > > If possible I would like to participate in "
> > > > Propellant Development Team "
> > > >
> > > > How can I help?
> > > >
> > > > Thank you
> > > >
> > > > José Miraglia
> > > >     _______________________________________________
> > > >
> > > >
> > > >       SS-Main mailing list
> > > >
> > > > SS-Main at sugarshot.org
> > > >
> > > >
> > > >
> > > > http://www.exrocketry.net/mailman/listinfo/ss-main
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
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> ------------------------------
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>  ------------------------------
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