[sugpro] Re: Verifying Motor Performance Through Flight Tests
- From: "Michael Monteith" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "michael_r_monteith@xxxxxxxxx" for DMARC)
- To: sugpro@xxxxxxxxxxxxx
- Date: Mon, 23 Feb 2015 16:58:43 -0800
That's no moon, it's a space station. lol I couldn't resist. Thinking of the
instrumentation that's piling up. But that's okay lots of hours of fun right?
I have been thinking about the affects of acceleration on some of the
instrumentation.
My thought is on a barometer isolating and closing off the air intake, flying
it,
the taking readings just to see. It may be a simple solution of direction it's
mounted.
Looking at that balloon data blows you away when you see how much everything
changes even at lower altitudes. Easy to see that there are some larger factors
at play than I certainly thought. That in itself was an education.
My wife will complain. "Not only are you working on rockets but you're wiring
up
some contraption, and now using all my cooking utensils." Oh well. It's all
part
the fun.
Thanks for all the discussion. I better keep my mouth shut and talk more
sugar.
Okay, let me clarify that. lol Sugar motors.
Michael
--------------------------------------------
On Mon, 2/23/15, Steve Peterson <steve_peterson@xxxxxxxxxxxxx> wrote:
Subject: [sugpro] Re: Verifying Motor Performance Through Flight Tests
To: sugpro@xxxxxxxxxxxxx
Date: Monday, February 23, 2015, 6:31 PM
I believe the Raven uses
the Intersema ms5541c which is an all-in-one
pressure sensor & ADC all temperature
compensated. I just skimmed the
online
Raven doc and it says 0.1mbar accuracy (as does the ms5541c
data
sheet). The Raven doc mentions the
Wyoming balloon data and as Shawn
points
out, you could always get your own pressure info on the way
down.
You'll need temperature to go
along with it in order to get density info
so there's a reason to dig out one of your
Arduino boards.
But
it's interesting that Adrian says you can't trust
the baro data
during powered flight--that
just tells you how tricky this stuff can be
because I hadn't gotten to the point of
even considering the effects of
acceleration on the baro sensor. But it makes
sense because to get 0.1
mbar resolution
means having a sensor that responds to very little
force. I can certainly see how a few Gs (or
more) would overwhelm
something that
sensitive.
To Shawn's
question of obtaining air density from descent rate for a
given parachute & mass: the Cd of a
given parachute varies dramatically
during
descent because of the oscillation (like a pendulum) and
because
of the lateral movement. Descent
times are notoriously difficult to
predict
because of that. So the short answer to the question is
"no".
Richard's site has some
info on this (thus bringing it back to sugar
rocketry :-)) which can be found at
http://www.nakka-rocketry.net/paracon.html
--Steve
On
02/23/2015 12:05 PM, Michael Monteith (Redacted sender
michael_r_monteith@xxxxxxxxx
for DMARC) wrote:
> Steve,
>
> I actually
didn't want to post it here as it was kind of off topic
in the sense it wasn't
> sugar
propellants in the strict sense but it is in the sense of
measuring results. I
> forgot to take
out the group email and put Richards in it so we could
discuss his
> findings. But that's
okay as long as others don't mind. I hate you
can't un-send. lol
>
> But glad I did in a way
too. I think your last statement sums it up.
It's fun and we
> learn
a lot from it.
>
> Hey, if I don't like the
limitations of the instrumentation I can build bigger and
better.
> Been there, done that too.
Guess if nothing else it will give me an excuse to work
> more with my Arduino boards. I'm used
to digging through datasheets as sometimes
> that's the best way to
find what is ideal for your specific use. Guess
I'll have to find
> out from the 2
altimeters I'm looking at which specific parts they
use.
>
> For this part going in I just
needed more of personal experience and what others have
> already done to at least start off with
and an altimeter setup that would suffice.
> I love the fact EggTimer TRS has gps and
radio for tracking and for that price I get
> altimeter and tracking.
Except I won't have accelerometer. Then with the raven
I have
> baro and accel but
lose gps and radio. If I had the money I'd just go
with the Altus but
> I love my marriage
thanks. I'm much better off with a little here and
there.
>
> Hey, if I have to do a
tethered balloon to obtain comparison data it might be the
way to go
> actually. I'd like to
see that report you're talking about.
>
> Discouraged? No Way.
Challenged? Great! Never know what might become of it..
Nothing
> if I don't try.
>
> Michael
>
>
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