[roc-chat] Re: Clarification
- From: Mike Riss <rockt_dude@xxxxxxxxxxxxx>
- To: roc-chat@xxxxxxxxxxxxx
- Date: Sat, 25 May 2013 12:53:02 -0700 (PDT)
I'd like to second Jeff's referral to a great rocketry resource:
thrustcurve.org
You can look at the complete thrust curve over time, and in particular, the
initial thrust. Look in the "Simulator Section" under "Options", one of which
is "View Data" (the icon with the magnifying glass). The initial graph is in
newtons, but there's an option to display in pounds.
Mike
--- On Sat, 5/25/13, Jeff Gortatowsky <indanapt@xxxxxxxxx> wrote:
From: Jeff Gortatowsky <indanapt@xxxxxxxxx>
Subject: [roc-chat] Re: Clarification
To: "roc-chat@xxxxxxxxxxxxx" <roc-chat@xxxxxxxxxxxxx>
Date: Saturday, May 25, 2013, 12:22 PM
Chris I have always used average thrust. But Carlo is right. The first second
of thrust appears to be about 45 or so pounds of thrust. That is a guess from
looking at the ROCKSIM graph on thrustcurve.org. I have a rocket at 6.5 pounds,
and an I100 with a 5 ft guide reaches 41 ft/sec at guide departure (according
to RS). I consider anything above 35 to ft/sec fine under normal conditions. (I
have gone as low as 28 to 30 tho some say that is too slow. But on a calm day
I've done it.)
---------------------------------------
Jeff Gortatowsky, Redondo Beach, CA | Twitter: JeffGortatowsky | Yahoo:
indanapt
"(Scientific) Skepticism is not a set of beliefs, it is a set of
methods for asking questions about reality." -- Doctor Steven Novella
From: Chris Coffee <chris_coffee@xxxxxxxxxx>
To: roc-chat@xxxxxxxxxxxxx
Sent: Friday, May 24, 2013 8:22 PM
Subject: [roc-chat] Clarification
A little help here, please? I need to know if someone can tell me if my
calculations are correct for a Thrust-To-Weight calculation for an upcoming
flight...and whether or not the rocket should be flown on said motor? Thank
you.
Madcow Sensor weighing in at 7 pounds on the pad. 54mm motor mount. Using a
Cesaroni I100-RL-LB this is what I got:
Average thrust of motor (according to ThrustCurve) = 98.5Ns
Divide 98.5Ns by 4.45 to get 22.13 average thrust in pounds
Divide 22.13 pounds of average thrust by 7 to get a Thrust-To-Weight ratio
of 3.16:1
Is this correct?
If my math is correct, I would say that the rocket should not be flown with
the I100.
Okay, folks.....school me!!! LOL
Christopher
L. Coffee
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