overklock
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- Apr 13, 2015
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Hey folks, Merry Christmas! Documenting the build of my level 1 rocket here. I decided to go with the Aerotech G-Force. Reason being - I'm familiar and used to 29mm reloads, and I know that with such a large heavy rocket, an H motor will fly nice, low and slow. Additionally, it's a "somewhat" easy build. I say somewhat because I screwed up the CG by adding too much epoxy on my first build. Pictures below, there's not many, I'll try to take more as I go. Any advice is always appreciated!
Starting with the motor mount, I used epoxy to secure the areas I knew would receive the most amount of stress, super glue for everything else.
Following up on the motor mount comes the fins. So, here's the thing. I know Aerotech builds generally do not need fillets as the fins are meant to "pop out" should there be a hard landing. However, there are two things at play here as to why I added fillets:
1. This is for my level 1. In order to get my level one, the rocket has to be flyable again after landing. A fin popping out defeats that purpose.
2. I think they look cool
Unfortunately, this wound up being too much for this seemingly delicate balance of CG to CP on this rocket. More on this later.
So, due to the excess rocketpoxy adding additional weight to the aft-end, my CG wound up being wonky. The Barrowman's method put the CG up just over 1" from the CP. However, the RockSim formula put it just above 4". This is obviously a huge discrepancy. Regardless, I was not comfortable with a CG/CP that close, and I decided to start over. Luckily, I had a second G-force for spare parts. I began to rebuild the lower half. Important to note that internal fillets using epoxy was done on both of these as well.
Fin filets before:
Fin fillets after. Much smaller, really just fills the gaps is all:
Redoing the bottom half knocked an additional 20 grams off the lower half of my rocket, resulting in a more stable simulation. The base weight of the aft end pre epoxy came out to 520 grams, total weight after epoxying everything together: 535 grams. This is in comparison to the whopping 555 grams of the previous aft build.
CG/CP on first aft build:
CG/CP after rebuilding the aft end:
Rocksim Stability Equation puts it in a much more favorable light, my understanding being that it accounts for base drag.
Everything glued together, now for my least favorite part of every build, filling the spirals and sanding. I keep promising to only run fiberglass builds in the future, yet here I am.
Anyway, this is where I am for now. I will be adding to this in the future. I'm still debating on using superglue on the coupler with sandpaper in order to harden/smooth the section that slides into the body. Apparently this particular rocket can have a hard time separating. Never done any kind of superglue "glassing" before. So if anyone recommends this or has tips please let me know.
Cheers, more updates to come!
Starting with the motor mount, I used epoxy to secure the areas I knew would receive the most amount of stress, super glue for everything else.
Following up on the motor mount comes the fins. So, here's the thing. I know Aerotech builds generally do not need fillets as the fins are meant to "pop out" should there be a hard landing. However, there are two things at play here as to why I added fillets:
1. This is for my level 1. In order to get my level one, the rocket has to be flyable again after landing. A fin popping out defeats that purpose.
2. I think they look cool
Unfortunately, this wound up being too much for this seemingly delicate balance of CG to CP on this rocket. More on this later.
So, due to the excess rocketpoxy adding additional weight to the aft-end, my CG wound up being wonky. The Barrowman's method put the CG up just over 1" from the CP. However, the RockSim formula put it just above 4". This is obviously a huge discrepancy. Regardless, I was not comfortable with a CG/CP that close, and I decided to start over. Luckily, I had a second G-force for spare parts. I began to rebuild the lower half. Important to note that internal fillets using epoxy was done on both of these as well.
Fin filets before:
Fin fillets after. Much smaller, really just fills the gaps is all:
Redoing the bottom half knocked an additional 20 grams off the lower half of my rocket, resulting in a more stable simulation. The base weight of the aft end pre epoxy came out to 520 grams, total weight after epoxying everything together: 535 grams. This is in comparison to the whopping 555 grams of the previous aft build.
CG/CP on first aft build:
CG/CP after rebuilding the aft end:
Rocksim Stability Equation puts it in a much more favorable light, my understanding being that it accounts for base drag.
Everything glued together, now for my least favorite part of every build, filling the spirals and sanding. I keep promising to only run fiberglass builds in the future, yet here I am.
Anyway, this is where I am for now. I will be adding to this in the future. I'm still debating on using superglue on the coupler with sandpaper in order to harden/smooth the section that slides into the body. Apparently this particular rocket can have a hard time separating. Never done any kind of superglue "glassing" before. So if anyone recommends this or has tips please let me know.
Cheers, more updates to come!
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