BDB
Absent Minded Professor
- Joined
- Aug 22, 2015
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To determine the optimal amount of FG wrap to apply to the BT of my L2 rocket, I decided to perform a kind of systematic study. The data is summarized here.
View attachment Glassed Tubes Test.xlsx
Layup Method
I started by cutting 2" lengths of 4" LOC tubing. I peeled the glassine layer and applied one or two wraps of 2, 4, and 6 oz FG cloth to them. I am a beginner at this technique, but I tried to follow the method shown by tfish in his YouTube video. I used peel ply to get a smooth finish, but did not vacuum bag the layups.
Texture
The peel ply made for a very smooth finish. Shown below are tubes reinforced with 6 oz + 2 oz, 6 oz + 4 oz, 6 oz + 6 oz glass wraps. The fine weave is only slightly smoother to the touch. I'm pretty sure that a good coat of primer and paint would completely cover the minuscule texture difference.
Materials
fiberglass fabric
6 oz E-glass: from West Marine
4 oz E-glass: https://www.fibreglast.com/product/4_...erglass_Fabric
2 oz E-glass: https://www.fibreglast.com/product/2_...erglass_Fabric
laminating epoxy
US Composites 635 epoxy with medium hardener: https://www.uscomposites.com/epoxy.html
peel ply
teflon-coated release fabric: https://www.aircraftspruce.com/catal...lickkey=131669
Strength Testing
To test the strength of the glassed tubes, I constructed a super-simple press. I applied 10 lbs of force to the top of the press and measured the distortion of the tube using a digital caliper.
Flight Simulations
I weighed each of the tubes before and after the layups and calculated the % increase in mass. I then extrapolated these data to predict the weight of a standard LOC IV kit with the different layups and simulated flights with Loki H144 and I405 motors using OpenRocket and the rocksim file for the kit from the Apogee Components website.
I'll save my interpretations of these data for a later post, but I really want to hear the comments from the members of this forum. In essence, the change in the mass of the BT reduces the apogee with the H144 by up to 20%, but the apogee with the I405 is nearly identical, even though the dry weight of the rocket has doubled.
View attachment Glassed Tubes Test.xlsx
Layup Method
I started by cutting 2" lengths of 4" LOC tubing. I peeled the glassine layer and applied one or two wraps of 2, 4, and 6 oz FG cloth to them. I am a beginner at this technique, but I tried to follow the method shown by tfish in his YouTube video. I used peel ply to get a smooth finish, but did not vacuum bag the layups.
Texture
The peel ply made for a very smooth finish. Shown below are tubes reinforced with 6 oz + 2 oz, 6 oz + 4 oz, 6 oz + 6 oz glass wraps. The fine weave is only slightly smoother to the touch. I'm pretty sure that a good coat of primer and paint would completely cover the minuscule texture difference.
Materials
fiberglass fabric
6 oz E-glass: from West Marine
4 oz E-glass: https://www.fibreglast.com/product/4_...erglass_Fabric
2 oz E-glass: https://www.fibreglast.com/product/2_...erglass_Fabric
laminating epoxy
US Composites 635 epoxy with medium hardener: https://www.uscomposites.com/epoxy.html
peel ply
teflon-coated release fabric: https://www.aircraftspruce.com/catal...lickkey=131669
Strength Testing
To test the strength of the glassed tubes, I constructed a super-simple press. I applied 10 lbs of force to the top of the press and measured the distortion of the tube using a digital caliper.
Flight Simulations
I weighed each of the tubes before and after the layups and calculated the % increase in mass. I then extrapolated these data to predict the weight of a standard LOC IV kit with the different layups and simulated flights with Loki H144 and I405 motors using OpenRocket and the rocksim file for the kit from the Apogee Components website.
I'll save my interpretations of these data for a later post, but I really want to hear the comments from the members of this forum. In essence, the change in the mass of the BT reduces the apogee with the H144 by up to 20%, but the apogee with the I405 is nearly identical, even though the dry weight of the rocket has doubled.
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