Oops! I launched my tiki drink!

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Alan R

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Wow. Finally mostly done. Only thing left is launch lugs and see how it flies.

This is the scratch built section, so .. everything was scratch built except for a BT20 motor tube, engine clip and launch lugs.

Maybe a few teaser posts before you get to see the whole thing?

Let's start with this.. hand rolled body tubes. When I was playing with this I realized that rolling BT's over a 2.6" tube I could use letter paper for the outside layer.
Letter paper .... pre-printed graphic ... sweet! No painting!

I made two. Didn't like the way the first one came out.
 

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Alan R

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Yes.. there IS a sim file. funny you should ask. I worked a long time on it ... lots of tweaking on the fin design to lower CP. Lots of tweaking to design as I built to reflect actual parameters (e.g. BT thickness). Playing with nose weight to pull up the CG. Early on realized this was going to be a C-motor rocket. Kind of like a Big Bertha.. lots of air to move out of the way.
Maximum C6 weight is 113g... just barely made it. I hope. I don't have a scale.

OR says 270' on a C6-3, probably more like 220-250?
00F0F_7QM813u3zVX_300x300.jpg
00F0F_7QM813u3zVX_300x300.jpg
 

Alan R

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Centering rings. From a triscuit box ... I happen to have a digital caliper. Did you know that triscuit boxes are .2mm thicker than a frozen fish box? It's true!

Doubled up the cardboard 90 degrees rotated and glued together. White glue on the cardboard, but Titebond on the motor tube

Thrust ring is 1/4" of an old motor.

Centering ring templates supplied by Open Rocket.

I forgot to cut a little notch for the clip to move. had to do that after the glue dried.
 

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Alan R

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Fins.. 6 of them. Four at the rear. Two mid-section. Scrap 3/32 balsa from all those other kits. I have whole bag of this stuff. Remember kids, your leading edge goes against the grain.
As you can see I labeled my templates, well, the first one anyway, the 2nd a little less, after that I think I had it figured out.
This particular fin shape it was easy to get things turned around once they were cut, so I red lined the root. But they were spray mounted anyway, so I needn't worry.
IMG_20200405_123941571.jpg
 
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Alan R

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Fins got a nice red oak stain before gluing on. Careful to keep that root edge raw!
My miter box makes a nice cradle / tube-marking tool for short birds.

Shock cord mount... Loop Kevlar around the motor tube, up through a straw in the MMT. Tie some elastic to it.

Another thing I forgot to do before I glued it in. Had to retrofit and drill a hole for the straw after the motor mount was glued in. Silly me. I should have known better.


IMG_20200408_195512079.jpg IMG_20200408_203201818.jpg
 

CalebJ

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Looking good. Question though: you said leading edge -against- the grain?
 

Alan R

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Question though: you said leading edge -against- the grain?
meaning .. grain is 90 degrees from direction of flight or whatever angle the leading edge of the fin is. that's against the grain
oh I re-read my post... ya .. it should say leading edge of the fin is WITH the grain. whatever. I know what i mean
 

BABAR

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I like it! look out, RoadRunner!
 

Alan R

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So I printed out that graphic, 2 images centered left and right and glue-wrapped it around my BT. The first time I tried it was on 20# cheap paper and when I pulled on the wrinkles it just tore instead of flattening out. It was also a hair short of meeting up. Three layers of kraft paper was a little too thick.
I started all over and rolled a third tube, 2.5 layers thick. Printed a new graphic on a piece of heavier paper I found laying around somewhere. It seemed to work much better, but there's still a wrinkle on upper corner where I couldn't get it straightened out in time.

Anyway, pre-printed body tubes might be a cool technique you could try sometime.

A couple of warnings: when it's soaked with white glue, easy to tear and not easy to keep aligned straight when rolling. And my graphic got scratched up a lot from just rolling around while I was gluing fins, marking lines, etc. I went back and touched up black and white parts with a sharpie and white paint.
Maybe tape off fin attachment points and give it a clear coat before gluing would hold up against scratches.
 

CalebJ

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Could you attach the graphic with spray adhesive rather than white glue?
 

Alan R

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Could you attach the graphic with spray adhesive rather than white glue?
dang. should have thought of that. HA. Would have been easier.
Whatever. In this case the graphic is an extra glued BT layer.
 

mbeels

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Nice! That nose cone really tops it off. Creative!
 

Alan R

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Nice! That nose cone really tops it off. Creative!
And there's the segue-way I was looking for. The nose cone was, er, problematic. Deserves a thread of its own. But here we go...
 

Alan R

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First off, I need to say that the little drink umbrella I had was the inspiration for this. I was thinking "Wow could I use this for a nosecone? What would the rest of the rocket look like?"

Right now I can't find it to show you, but the color and flower design were copied from the original.

The original was too small and fragile for this so I had to recreate it.
 

Alan R

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Back to the nosecone.
I had the dimensions for it from OR (6x9cm), but just a paper shroud wouldn't really work. Plan was to do a paper shroud, glue some balsa umbrella sticks in it, and use a 3d printed insert for the shoulder and strength.
First, I went here and got a pattern: https://www.blocklayer.com/cone-patternseng.aspx This is a very nice site for all kinds of patterns and calculations.
I added the glue flap and 8 lines to use for stick guides.
Painted the back side of the pattern first, then cut it, then glued the sticks in. Forming the cone and gluing the tab was the last step.

IMG_20200406_161100514.jpgIMG_20200406_201020394.jpgIMG_20200407_091908850.jpgIMG_20200407_091922073.jpg
 

BABAR

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So I printed out that graphic, 2 images centered left and right and glue-wrapped it around my BT. The first time I tried it was on 20# cheap paper and when I pulled on the wrinkles it just tore instead of flattening out. It was also a hair short of meeting up. Three layers of kraft paper was a little too thick.
I started all over and rolled a third tube, 2.5 layers thick. Printed a new graphic on a piece of heavier paper I found laying around somewhere. It seemed to work much better, but there's still a wrinkle on upper corner where I couldn't get it straightened out in time.

Anyway, pre-printed body tubes might be a cool technique you could try sometime.

A couple of warnings: when it's soaked with white glue, easy to tear and not easy to keep aligned straight when rolling. And my graphic got scratched up a lot from just rolling around while I was gluing fins, marking lines, etc. I went back and touched up black and white parts with a sharpie and white paint.
Maybe tape off fin attachment points and give it a clear coat before gluing would hold up against scratches.
Print it on adhesive backed label paper to begin with.

Love the design. Remember, no smoking within 24 hours of launch, and no drinking within 25 feet of the pad.

I was thinking Friki Tiki. Reminds me of the Disneyland Tiki Room show, I always enjoyed that one.
 

Alan R

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Nicely done. You could also make a nose cone shoulder from rolled cardstock and two cardboard bulkheads (to hold the shape).
Well I have a 3d printer, so it was easy enough (I thought!) to just make a strong insert.

I was on a Blue Hawaiian binge one summer way back when. The trunk had a cooler full of ice, P-juice, Curacao. Crazy times. But this is not really blue
 

Alan R

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Print it on adhesive backed label paper to begin with.
Possible, but at the time I was just thinking it would be the top layer of the tube. And I don't have any label paper laying around. This is all .. materials on hand.

Love the design. Remember, no smoking within 24 hours of launch, and no drinking within 25 feet of the pad.
What's the fun in that?
 
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