Thank you!!! Understanding more. Excellent advice.
From: Tom Hanan
Sent: Tuesday, June 16, 2015 10:47 AM
To: roc-chat@xxxxxxxxxxxxx
Splash modeling is great but its an order of magnitude better IF you close the
model loop by launching a short duration version of a motor with the same
initial impulse to minimize the splash window for the test launch. You need to
add weight to keep "all things equal" with the lighter shorter duration motor.
This is much easier to do in the amateur world with re loadable motors that
allow you to include spacer or different grain formula to reduce burn time.
Unfortunately the solids tend to have reduced initial thrust based upon smaller
grain surface area unless the formula compensates for that. But hybrids can be
light loaded to deliver short test flights.
All of this is the same thing we tell newbies. Launch with a smaller shorter
duration motor first to get a feel for the airframe before you take you
altitude shot! Just because its harder and more complex with laregr motors does
not mean that we shouldn't be doing it! After all it is that desire to master
MORE complexity that draws many of us to larger rockets with higher power.
On 6/16/2015 10:29 AM, Cliff Sojourner wrote:
You can do splash for models, for example spot landing contests.
Does anyone know, does openrocket do splash analysis?
On June 16, 2015 9:45:20 AM PDT, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
So motor variability includes thrust vectoring?
Hum… all parameters varied?
OK, I’ve never done that because I haven’t even come close to launching a high
alt rocket. So, please forget my reference to the splash analysis. Perhaps
for now just keeping the topic to the <20K’ rockets?
James, next time you do the analysis for one of your high alts, please let me
see the results and the track the rocket actually took. Maybe someday, way in
the future, I’ll need to do this.
From: James Dougherty
Sent: Tuesday, June 16, 2015 9:20 AM
To: roc-chat@xxxxxxxxxxxxx
What Cliff said :-)
Sent from my iPhone
On Jun 16, 2015, at 6:00 AM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
So the analysis does take into account launch angles. But, what’s the maximum
angle? Wow, than a high launch angle and altitude could take your rocket out
of even Black Rock and it would be acceptable? I've heard that in the future
FAA is interested in roll control. I wonder why and if launch angle (intended
and true) would be important.
From: Cliff Sojourner
Sent: Monday, June 15, 2015 11:51 PM
To: roc-chat@xxxxxxxxxxxxx
On 2015-06-15 11:46, R Dierking wrote:
This is an interesting problem, and a solution would help many people. Really,
what’s the use developing a complex ‘splash’ analysis for a high alt flight if
you don’t even know what direction the rocket will be going 20’ off the ground!
And, if you are off 5 degrees at that point, it makes a lot of difference
where your rocket is going to be at +10K’.
hi Richard, not picking on you tonight, really :) Splash analysis is a "monte
carlo" simulation, many many flights with all parameters varied, such as launch
angle, wind speed and direction, motor variability, etc. at the end you can
say with great statistical confidence that the rocket really will fly and land
somewhere on the splash chart.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
--
Regards,
Tom Hanan
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