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Upscale Quinstar build(s)

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neil_w

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K'Tesh mentioned upscaling a Quinstar. I thought "ha ha that's crazy" but the idea seems to have wedged itself in my brain. It is highly unlikely I'd ever actually do this but it's fun to consider anyway.

I would design it for 29mm black powder motors, probably with a BT60 body tube, which would make it a 1.67:1 upscale, with diameter a bit over 13". Not bad. A 3+ second burn with a F15 would be fun.

Anyhoo, apart from the "interesting" task of cutting all the wood pieces, I don't have any real idea how to gauge the flight-worthiness of this hypothetical beast. How would I guess what weight of wood to use, or how much the whole thing should weigh? I was thinking 1/8" balsa might work OK, maybe with papering of a few of the most-stressed parts (assuming I could even guess which those are).

Or would the best approach in such an instance be to just build the darn thing and see what happens?

Would this be cool enough to be worth the (considerable) effort?
 
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TangoJuliet

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30 years ago none of us "sim'd" any of our model rockets. If we had an idea or upscaled something, we just did it. Sometimes we were successful, sometimes... Not so much. I watched a 3x Alien Explorer shred fins off the launch pad. Unsuccessful, but fun to watch!

I say, build as light as you can, but add strength where you need it. Contest grade balsa is extremely light, but also not very strong. Look into using other materials like carbon or G-10 composites.
 

neil_w

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30 years ago none of us "sim'd" any of our model rockets. If we had an idea or upscaled something, we just did it. Sometimes we were successful, sometimes... Not so much. I watched a 3x Alien Explorer shred fins off the launch pad. Unsuccessful, but fun to watch!
Although a good shredding makes for nice if brief launch pad entertainment (which I got a chance to experience this year), I would *really* not want this one to go that way, given the effort it would take.

I say, build as light as you can, but add strength where you need it. Contest grade balsa is extremely light, but also not very strong. Look into using other materials like carbon or G-10 composites.
I'm not equipped nor interested in doing composites, so this would have to be an all-wood affair. I would certainly not use contest grade balsa, learned that lesson once already. I think/hope good-old medium weight balsa of the appropriate thickness, papered and/or reinforced where necessary (who knows where that is though) could conceivably do the trick. Or maybe basswood in some places. But I don't really know how to judge, and I'd like to be able to convince myself there's a decent chance of success before going forward.

I'm finding this to be an intriguing possible project because it's a large amount of balsa work, which I enjoy, and minimal finishing work, which I do not. I think the end result would be pretty cool.
 

Charles_McG

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An Estes blender scaled to 29 mm is a great way to burn a G 80 motor. I used 3 mm plywood.
 

neil_w

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Hmm, that'd be a bit on the heavy side but would certainly be strong. Unfortunately with plywood I'd need to have it laser cut, no chance of cutting all that by hand. Laser cutting is a possibility though.
 

K'Tesh

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Hmm, that'd be a bit on the heavy side but would certainly be strong. Unfortunately with plywood I'd need to have it laser cut, no chance of cutting all that by hand. Laser cutting is a possibility though.
Two words...

Scroll saw
 

neil_w

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Two words...

Scroll saw
Three and a half words: Don't have one.

Not gonna get one just for this either. I'm thinking ply would be a little heavier and stronger than needed here (an F15 is quite a bit less stress than a G80!). Still just pondering.
 

Cabernut

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I say just build it and if there's a failure point, strengthen and try again. At the pad I'd make sure people know it's a heads-up situation.
 

neil_w

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Actually, even just laminating two sheets of 1/16" balsa together (without anything in between) would be a lot stronger than a single piece of 1/8". Although it would mean twice as many pieces to cut. :eyeroll: Although cutting a bunch of 1/16" balsa would probably be really quick and easy... Hmm.
 

K'Tesh

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Three and a half words: Don't have one.

Not gonna get one just for this either. I'm thinking ply would be a little heavier and stronger than needed here (an F15 is quite a bit less stress than a G80!). Still just pondering.
Ok... However, you might want to make the investment if you're moving up to HPR and upscaling things. I guess it's not so necessary if you have access to a laser cutter. But if you don't, it does (pun intended) cut down the time needed to make your own fins.
 

Charles_McG

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I knocked out 165% scale vector art tonight. For 38mm motor mount. I have a 29-38mm adapter handy :).

It takes 2 12x24" sheets. I only have 1 handy, so I guess I can't have the boy cut it at school tomorrow.

I should probably take time to check some of the slots and gaps, too. I can resize them for the thicker board.
 

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Cool! Soft squishy balsa is pretty light and strong if you paper it. Two-ply 1/16" balsa (cross-grain laminated) with papering will be even stronger. If you do this, precut the pieces first before gluing together or get the said scrollsaw/dremel/bandsaw. I made some 4-ply laminated corrugated cardboard weapons with white glue for my kid's Halloween costume and had a heck of a time trying to cut through with a box cutter.

Can you build an upscale Starfury instead? :) :) :)
 

neil_w

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Well that is moving quickly. 😲 I'd love to get your drawings if possible. What kind of wood are you going to use?
 

Nytrunner

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Foamcore posterboard? Easy to cut, easy to join? Doesn't give splinters when it lands on your head?
 

Charles_McG

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3mm ply from Menards. Nothing fancy. It's cheap and we have practice cutting it.

And it may seem screwy in this age of 'sharing', but I'm reluctant to share my files of in-production kits.
 

neil_w

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3mm ply from Menards. Nothing fancy. It's cheap and we have practice cutting it.

And it may seem screwy in this age of 'sharing', but I'm reluctant to share my files of in-production kits.
As you prefer, although I already own one of these, just didn't think to scan the balsa sheets before I built it. Would be hard to jam it in the scanner now. :)
 

Charles_McG

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No kidding. I try to remember to scan everything these days. And I'm pondering how to do 3D scans of these Mercury Atlas parts I have here.

As you upscale, watch the width of the slots. I'm adjusting my files for thicker than scale boards. Not hard in Illustrator, but tedius.
 

neil_w

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My recollection is that the slots were actually a bit oversized to begin with. On a larger model I'd probably prefer slightly tighter fit, and so my plan was actually to cut them undersized (or maybe scale-sized) and then enlarge them with sanding as needed.
 

neil_w

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I don't mind sanding wood (or at least, balsa and basswood... sanding plywood is a bit more of a project), but I hate sanding paint, especially primer, and right now the APRO Lander II is staring at me in it's fully primered glory. Yay.
 

Cabernut

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Rockets ain't bad compared to scale R/C airplanes.
Indeed. Whenever I feel a bit overwhelmed when some rockets need tedious effort, I just remember my grandfather & uncle building RC planes and the massive tedious effort and patience that went into those. To this day the smell of fresh epoxy reminds me of watching them work.
 

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1/8" balsa should be fine on this. An F15 black powder motor won't put that much stress on it. Adapt down to a D12 for a test flight.
 

neil_w

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1/8" balsa should be fine on this. An F15 black powder motor won't put that much stress on it. Adapt down to a D12 for a test flight.
I'm definitely thinking of 2 laminated 1/16" balsa sheets, which is almost the same thing but should be stiffer. It'll be a lot (!) of cutting but I'm thinking this could be a nice background project so I always have some balsa work waiting for me while other builds are on hold (like waiting for paint to dry or somesuch).

In any case, in order to start this I'll need to track down some scans of the balsa sheets.
 

TangoJuliet

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Typically, creating a lamination of thinner balsa wood to create a balsa "ply" is done with a minimum of three layers with the middle layers grain running perpendicular to the other two. If you're using two layers with the grain running in the same direction then you're not really adding any more strength than you would get from just using 1/8" balsa and filling and priming properly. If you're going to use two layers with grain in opposite directions, then you'll get "end grain" on your leading edge on one side.
 

neil_w

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Typically, creating a lamination of thinner balsa wood to create a balsa "ply" is done with a minimum of three layers with the middle layers grain running perpendicular to the other two. If you're using two layers with the grain running in the same direction then you're not really adding any more strength than you would get from just using 1/8" balsa and filling and priming properly. If you're going to use two layers with grain in opposite directions, then you'll get "end grain" on your leading edge on one side.
In my (limited) experimentation here, I have found that even laminating two plies with grain in the same direction is noticeably stronger than a single solid piece of equal thickness. I'm keeping the grain in the same direction because I'm primarily trying to add strength in the direction of the grain (actually, for a few of the pieces I might go at right angles; those don't have a "leading edge" per se).

So I'm not creating a plywood in the traditional sense, just trying to eke out a bit more strength from what I've got. I'll do a bit more experimentation before committing to this approach, so I can convince myself that I'm not full of it.
 

Cabernut

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I would suggest try papering the hard way - with thinned Elmer's and office paper as shown in one of Apogee's videos. I have a few fin sets done this way that are noticeably much stronger.
 

neil_w

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At the scale I'm targeting, I need sheets at least 6" wide. Balsa sheets of that size exist, but seem to be fairly difficult to acquire economically. It's not clear if basswood sheets exist at that size.

And so, unless I can luck into a good supply of 6" balsa sheets, I would be forced to go with plywood, and in that case this project becomes much less attractive to me.

So for now I'll look forward to Charles_McG's build and keep trying to figure out a practical way to build this for myself.
 

KenRico

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I love my 38mm Funk Saucer @ 12 oz can fly on 29mm also .. but still allows me to fly a 38 long burn like the mellow and H45 DMS.

Kenny
 
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