[roc-chat] Mixing Fiberglass Types
- From: "Chris Coffee" <chris_coffee@xxxxxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Mon, 24 Dec 2012 13:36:47 -0800
Is it safe, or an acceptable practice, to use two different fiberglass types
and wall thickness on a single rocket? I am toying with the idea of adding a
second (upper) section of body tube to my FG Little John in order to make it
dual deploy. I was given a 4-inch wide and 33” long section of fiberglass tube
that I was thinking of using, but I noticed a couple of differences. One of
them being that the 33” (upper) tube is 0.06” wall thickness and the lower tube
is at 0.07” thickness. Another thing is that the lower tube is 2” shorter than
the top (33” top tube and 31” lower tube). I also noticed what to me seemed
that the upper tube is a different type, or style of FG. In the picture below
you can see how the left tube is more of a yellowish color (like the G10 fins)
and the current rocket tube is more of a bluish-green. I know color itself
does not make a difference, but I noticed that the woven fiber is a lot more
visible in the current body tube. So....
1. Can I use the two different tubes with different wall thicknesses and be
okay? Or should both top and bottom tubes be the same thickness?
2. Can someone tell me what the difference is between the two tubes in regards
to composition?
3. Do both the top and bottom tubes have to be of equal length or is the 2”
difference acceptable?
I ran the finished design through OpenRocket and it does not display any
issues. On a K540M-14 it shows Apogee at 7,127 ft. and a speed of Mach 1.03. I
just want to make sure that mixing the two is not going to cause any issues.
Thanks.
Christopher L. Coffee
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