[AR] Re: dynamic stability
- From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Thu, 21 Aug 2014 12:32:54 -0600
There's a machine for that at Wallops....
Bill
Sent from my iPhone
On Aug 21, 2014, at 11:29, Carl Tedesco <ctedesco@xxxxxxxxxxxxxx> wrote:
> Thanks Bill. Now to figure out how to spin a 21 foot long, 12" diameter
> rocket.
> --- Carl
>
> On 8/21/2014 9:43 AM, Bill Claybaugh wrote:
>> Carl:
>>
>> I believe FAA is looking for the 6DOF moments which are required inputs to
>> any dispersion analysis.
>>
>> If your vehicle is fully axisymmetric the pitch and yaw moments should be
>> the same. However, that is rarely the case in the payload and any asymmetry
>> will induce coning unless balanced. This is why dynamic balancing is
>> required on all professional payloads.
>>
>> If you are flying a liquid I would strongly recommend dynamic balancing the
>> entire vehicle (a very good practice even if you are flying a fully
>> symmetric solid--density variations in the propellant can influence
>> stability). Static stability testing is not sufficient.
>>
>> Bill
>>
>> Sent from my iPhone
>>
>> On Aug 20, 2014, at 15:45, Carl Tedesco <ctedesco@xxxxxxxxxxxxxx> wrote:
>>
>>> I am starting the process for getting a class 3 waiver for a rocket launch.
>>> Most of the FAA required documentation looks straight forward. One piece of
>>> information they require is "The dynamic stability characteristics for the
>>> entire flight profile." A static stability analysis is straight-forward,
>>> but I have never done a dynamic stability analysis.
>>>
>>> How have folks on this list addressed this requirement? Is this software
>>> driven analysis or just hand-calculations? Does anyone have an analysis
>>> they could share? If software analysis is the norm, can anyone point me to
>>> affordable software?
>>>
>>> --- Carl
>>>
>>> --
>>> Carl Tedesco
>>> Flometrics, Inc.
>>> 5900 Sea Lion Place, Suite 150
>>> Carlsbad, CA 92010
>>> tel: 760-476-2770 ext. 515
>>> fax: 760-476-2763
>>> ctedesco@xxxxxxxxxxxxxx
>>> www.flometrics.com
>
> --
> Carl Tedesco
> Flometrics, Inc.
> 5900 Sea Lion Place, Suite 150
> Carlsbad, CA 92010
> tel: 760-476-2770 ext. 515
> fax: 760-476-2763
> ctedesco@xxxxxxxxxxxxxx
> www.flometrics.com
>
>
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