[SS-VehDev] Re: [SS-Main] new Propellant Team member
Rich Nakka
richnakka at rogers.com
Fri Oct 7 09:31:28 PDT 2005
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
> <mailto: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
>> <mailto: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
>>> <mailto: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 <mailto: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> <mailto: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 <mailto: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
>>>>
>>>>
>>>> <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 <mailto:SS-Main at sugarshot.org>
>>>> http://www.exrocketry.net/mailman/listinfo/ss-main
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>> _______________________________________________
>>> SS-Main mailing list
>>> SS-Main at sugarshot.org <mailto:SS-Main at sugarshot.org>
>>> http://www.exrocketry.net/mailman/listinfo/ss-main
>>>
>>>
>>>
>>
>>
>
>
>
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