PhlAsh
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- Joined
- May 9, 2011
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As reconstruction on UFO Invader x4 was winding down, I began scoping the Next Big Project. The loss of one of my favourite rockets to bay-effect winds clinched the deal. I would upscale Estes Alien Invader.
4x was a no-brainer scale for me plenty of room and plentiful components. The real decision lay in the version. Should I build the 1281 version (which ran from 1976-81) or the 3003 version (which ran from 2010 to 2013)? The most obvious difference is that the pod tubes of the latter are 5/16 further aft than they are on the former. The sticks are ¼ further fwd on the 3003 too. Id build the 1281 in 78 and flew it for a number of years. It, along with all my other rockets (except the X-Wings) were relegated to the dumpster by my parents. Once the kids had become interested, I build the 3003, which ended up in a neighborhood between the launch site and the Chesapeake Bay. I like the look the further-aft pods give it, so I went with the 3003.
The kit presented a number of challenges; a cock-eyed pod could send it spinning, misaligned fins would stand out like a sore thumb, and getting some strength into those buttress fins was something not covered in the instructions.
My first goal was to create a virtual 1:1 Alien Invader. I took the RockSim file from RocketReviews and rebuilt it based on the 3003 instructions. At the same time, I dropped the instructions into AutoCAD and digitized the wood pattern. That gave me more accurate dimensions to send back to RockSim. Once the sim was done, I could use RockSims Scale function (why is there a separate flyoff for By Scale Factor? Its not like theres another choice.) and take it up to 4x. The projected mass was 44 ounces. That would probably triple by the time all was said and done.
I chose to use a 54mm motor mount largely because, apparently if youre a SEVRA member and you dont, your manhood falls into question. I thought I was approaching a deal on 4 Blue Tube. That didnt pan out, so I got two sticks, a coupler, a stick of LOC 54mm tube and a 54mm AeroPack.
Once I CADd up the wood, determined centering ring locations and TTW sizes/locations, I picked up 3 pieces of ¼ aircraft plywood. I figured that cladding the fins in 7oz fiberglass would get them near the 3/8 scale thinckness without going overboard. I also CADd up the slots for the TTW fins, dialed in the Sim using the actual components and modeled the rest of the rocket in AutoCAD. That resulted in DWGs that could be sent off to fellow SEVRA rocketeer and upscaler extraordinaire, Joe Zawodny. Joes slotting jig and CNC table made short work of producing parts.
4x was a no-brainer scale for me plenty of room and plentiful components. The real decision lay in the version. Should I build the 1281 version (which ran from 1976-81) or the 3003 version (which ran from 2010 to 2013)? The most obvious difference is that the pod tubes of the latter are 5/16 further aft than they are on the former. The sticks are ¼ further fwd on the 3003 too. Id build the 1281 in 78 and flew it for a number of years. It, along with all my other rockets (except the X-Wings) were relegated to the dumpster by my parents. Once the kids had become interested, I build the 3003, which ended up in a neighborhood between the launch site and the Chesapeake Bay. I like the look the further-aft pods give it, so I went with the 3003.
The kit presented a number of challenges; a cock-eyed pod could send it spinning, misaligned fins would stand out like a sore thumb, and getting some strength into those buttress fins was something not covered in the instructions.
My first goal was to create a virtual 1:1 Alien Invader. I took the RockSim file from RocketReviews and rebuilt it based on the 3003 instructions. At the same time, I dropped the instructions into AutoCAD and digitized the wood pattern. That gave me more accurate dimensions to send back to RockSim. Once the sim was done, I could use RockSims Scale function (why is there a separate flyoff for By Scale Factor? Its not like theres another choice.) and take it up to 4x. The projected mass was 44 ounces. That would probably triple by the time all was said and done.
I chose to use a 54mm motor mount largely because, apparently if youre a SEVRA member and you dont, your manhood falls into question. I thought I was approaching a deal on 4 Blue Tube. That didnt pan out, so I got two sticks, a coupler, a stick of LOC 54mm tube and a 54mm AeroPack.
Once I CADd up the wood, determined centering ring locations and TTW sizes/locations, I picked up 3 pieces of ¼ aircraft plywood. I figured that cladding the fins in 7oz fiberglass would get them near the 3/8 scale thinckness without going overboard. I also CADd up the slots for the TTW fins, dialed in the Sim using the actual components and modeled the rest of the rocket in AutoCAD. That resulted in DWGs that could be sent off to fellow SEVRA rocketeer and upscaler extraordinaire, Joe Zawodny. Joes slotting jig and CNC table made short work of producing parts.