Loc Precision BIG NUKE 3E Kit

Steven88 said:

I’m thinking about either going with three rail buttons or moving the bottom one 5” up from the bottom. Is there any harm in having three rail buttons? You don’t normally see it but what could be the harm as long as they all line up?

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Personally, I wouldn’t do that. The downside is (as you’ve stated) getting them lined up such that you don’t cause a binding effect with the rail channel. Three buttons also adds to friction when the rocket is traversing the rail, and adds a small amount of increased aerodynamic drag.

In short, I don’t see any benefit to adding a third rail button, but I do see downsides in doing so. Why take that added risk?

I don’t see what you have as something that is broken and needing to be “fixed”, but perhaps I’m missing something. Wouldn’t be the first time!

Steven88 said:

Is there any harm in having three rail buttons?

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Probably not, except maybe for a little more drag, but they are a PITA to align.

Steven88 said:

I’m thinking about either going with three rail buttons or moving the bottom one 5” up from the bottom.

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IMHO you're overthinking this. You could put the lower button in the bottom centering ring or you could move it up a few inches, either is fine. You don't have to have them in the centering rings, you can just drill and tap the cardboard tube and epoxy the screws in for a rocket of this size. As others have said, you don't want three buttons, they are a pain to align and there's little benefit.

I think they usually have the top button at or just above the center of gravity with the heaviest motor. Best position to control the rocket. The bottom button is usually in the bottom centering ring to provide guidance as long as possible as the speed comes up to where the fins start working. A third button won't hurt anything as long as they do line up.
Moving the bottom button up 5 in. probably wouldn't hurt anything, but I wouldn't go any more than that, and I wouldn't do it unless there was a design or clearance issue that made it necessary.

Decided to go with two buttons, thanks guys. What size of pressure relief holes do you recommend I drill for the bottom and top sections of the actual rocket? It will go around 11k at the highest. Is one 1/8” pressure relief hole in each section sufficient?

Should be enough.

No harm in 3 buttons. BUT, your asking for binding. Especially on a dirty rail. Getting three to line up is not as easy as you think. That being said Ive never used 3. Just my experience as pad manager and RSO. My Big Nuke buttons are at 3" and 16".

And my vent holes are 1/8", one in bottom one in top.

Do you guys normally put sanding sealer on your plywood fins on your rockets before primer/paint or consider primer and paint good enough?

I do. Is it necessary ? no. For plywood I use water based. No smell, easy clean up with warm soap and water. Doesn't sand quite as easy as the lacquer or SIG based. But much safer. And cheaper. Balsa I use SIG.

For my BigNuke the fins are fiberglassed. So a thick waterbased sealer filled in the weave nicely.

jbsommerfeldt said:

I do. Is it necessary ? no. For plywood I use water based. No smell, easy clean up with warm soap and water. Doesn't sand quite as easy as the lacquer or SIG based. But much safer. And cheaper. Balsa I use SIG.

For my BigNuke the fins are fiberglassed. So a thick waterbased sealer filled in the weave nicely.

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So, what water based sealer do you use? And is it sandable?

Steven88 said:

Do you guys normally put sanding sealer on your plywood fins on your rockets before primer/paint...

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On plywood I use 2-3 coats of Elmer's CWF thinned with water, sanded in between coats.

PatD said:

So, what water based sealer do you use? And is it sandable?

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When I built an Estes Big Bertha a year or so back, I used this. It is relatively thick, so dilute it to your liking so that it fills the grain but does not get the wood too wet. Let it dry, and then lightly sand with a fine (400 grit works for me) sandpaper. Repeat this process until you are happy with the appearance of the fins.

Apogee Rockets has some really good videos online through either their website or YouTube that you may want to check out for this kinda stuff.

My error, I was wondering about a sprayable sealer/primer that would work with water based acrylics like createx auto air.

Edit: To be clear, I'm talking about waterborne, sandable, sprayable sealer/primer.

What ever generic is on sale at Menards that week. I brush it on. Spryable, idk? I guess you could water it down and use a large nozzle.

The water based is diffently not as sandable as chemical types. But if you constantly swap out the sand paper, since it gums up, its good enough. When doing large pieces water based (for me) is just safer and easier clean up.

Primer is really to aid adheshion. IMO. If you need to fill the grain, I would use some type of light weight filler. Ive used balsa fill, spackling and everything inbetween.

Rustoleum 2x works great without primer, its primer + paint. I wouldnt guarentee it "fills" grain or imperfections.