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Kehoes23

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Has anyone built the Giant Leap Vertical Assault rocket? I have the fiberglass version, it's been in the closet for a few years waiting to be put together, just wondering how hard it is to glue up the fincan and what method you used to do it? Thanks for your advice.
 

dixontj93060

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I did not build one, I rehabbed one I bought from a TRF member a decade back. It is a great rocket. But to your question, it's a fin can--nothing easier than that. Apply epoxy, slide fin can on, wipe away excess epoxy with alcohol, let cure.
 

fyrwrxz

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Ditto-+1 for the new electronics-mine used a blacksky timer. Ironically I core sampled the sustainer on motor recovery flying it single stage. It's been in the fix pile too many years.
 

Kehoes23

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After you glue the fincan on the motor mount, then glue it to the airframe, what method do you use to fill in the gap between the fin and airframe?
 

dixontj93060

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After you glue the fincan on the motor mount, then glue it to the airframe, what method do you use to fill in the gap between the fin and airframe?
Normal filleting epoxy. Bob Smith 15 minute or RocketPoxy. Both will thicken/gel fairly quickly and reduce any sag. Advantage to RocketPoxy is that filling any "shallow" areas is easy by letting it cure to the putty state and using it like a filler. Here is an older review that refers to the gap sagging: http://www.rocketreviews.com/giant-leap-rocketry-vertical-assault-30-by-philip-levanda.html, so probably better to use the higher viscosity RocketPoxy.
 
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Lowpuller

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I have learned my new favorite for fillets is JB Weld, after just a few minutes it holds its shape and has a long working time.
 

dhbarr

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I have learned my new favorite for fillets is JB Weld, after just a few minutes it holds its shape and has a long working time.
Substantially heavy, though.
 

NateLowrie

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I have learned my new favorite for fillets is JB Weld, after just a few minutes it holds its shape and has a long working time.
I use US composites laminating epoxy (Both 3:1 and 4:1 hardener) with glass microballoons. Get a Tub of Microballoons from Amazon for $8 and it will last you for MANY builds. I mixed roughly 1:1 weight to weight. It thickens the epoxy to a peanut butter/toothpaste like consistency. You can use it with any epoxy. For external fillets, the surface is very smooth and it sands extremely well.
 
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dhbarr

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I use US composites laminating epoxy (Both 3:1 and 4:1 hardener) with glass microballoons. Get a Tub of Microballoons from Amazon for $8 and it will last you for MANY builds. I mixed roughly 1:1 weight to weight. It thickens the epoxy to a peanut butter/toothpaste like consistency. You can use it with any epoxy. For external fillets, the surface is very smooth and it sands extremely well.
Glass, phenolic, or carbon balloons?
 
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NateLowrie

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Glass, phenolic, or carbon balloons?
Glass balloons. I have used phenolic in the past but not carbon. I linked to the amazon page of the tub I use. It's the System Three stuff. I had a tub left over before I started using the US composites epoxy. If you are ordering the US Composites epoxy, their 3M glass microspheres on the fillers page (http://www.uscomposites.com/fillers.html) are equivalent and cheaper. That quart will last you through at least 20 builds.

Regarding other US Composites fillers:
  • I have used the fairing compound and it is decent. I found it unnecessary because the microballoons do the same function.
  • The 1/32" milled fiberglass is a good thickening agent that imparts some additional strength to the epoxy fillet. Use it on internal applications. The finish surface is too rough for external joints like fillets and it doesn't settle as well as the microballoons.
  • The 1/4" chopped fiberglass strand I would stay away from. When I mixed it into the epoxy I expected the strand fibers to separate from each other and make a nice hairball mix but in practice the strands separated poorly and just floated in the mix. Get chopped CF from another source if you want to go down the fiber route. Chopped fiber is used to impart considerable additional strength to the joint. Only use for internal joints as the peanut butter hairball is very messy and will not create anything close to the smooth fillet look you are after.

I have not tried any of the other fillers.
 

Bat-mite

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I have one, the Quantum Tube version, and I did a build thread on it, but it turned out pretty crappy. I did get my L2 on it, though. And it survived a water landing.
 

smapdiage9

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I built the fiberglassed one back in 08 or 09, got L1 and L2 on it. Stuck it in a tree so hard I had to pull it out with my truck, zipppered the fin can, replaced 16" of airframe, it now flies my ex motors so I don't blow up the nicer rockets. A good, solid rocket, if a bit outdated and expensive.
 

Kehoes23

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ImageUploadedByRocketry Forum1481467363.718030.jpg
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Here are a few pictures of the gap between the fins, motor mount and airframe that I'm talking about.
 

dixontj93060

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Here are a few pictures of the gap between the fins, motor mount and airframe that I'm talking about.
Perfect application for RocketPoxy. I'd use it to fill all the gaps first to a level point. Then sand with 120 grit and use the same stuff to apply the fillets.
 

Onebadhawk

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JB Weld isn't good for fillets guy's...
It's too brittle...
It'll crack for sure...

Teddy
 

GRIFFIN

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I have used JB exclusively on the last 7-8 builds of mine. Haven't found it to be an inferior material.

My $0.02
 

cherokeej

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For filling gaps... Y'all are on the right track with micro-balloons and epoxy. I would suggest a good portion of fused silica to thicken up the mix, too.

Years ago, we needed a design for the ARLISS-K bird. We adopted the VA design. Quick, easy build, and everything we needed to deploy 2.6" sats at altitude. But we scratch built 'em using FWFG a/f tubing, and cut the fin cut-outs in a diamond shape to match the fin can. Made it easier to clean up the lines with some nice fillets.

They fly great on the K550's we use now. But I remember using the K700's. Those things absolutely ROCK on the AT K700.
 

Onebadhawk

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That's funny Jason,,
I always found JB to get so hard that it would crack / be a bit brittle...

Teddy
 

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