[roc-chat] Re: [roc-chat] Re: Clarification

From: "chris_coffee@xxxxxxxxxx" <chris_coffee@xxxxxxxxxx>
To: roc-chat@xxxxxxxxxxxxx
Date: Sat, 25 May 2013 13:18:58 -0700

Thanks everyone. With that being said then I will let him know that he should 
be good to go for launch. Hope to see everyone there. 

Sent from my Verizon Wireless HTC DNA 4G LTE Smartphone

----- Reply message -----
From: "Jeff Gortatowsky" <indanapt@xxxxxxxxx>
To: "roc-chat@xxxxxxxxxxxxx" <roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Clarification
Date: Sat, 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

[roc-chat] Re: [roc-chat] Re: Clarification

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