A rocket for a smurf

[Funkworks]

Based on that description, I'll guess that the blue hard cover second from the bottom could be Jackson, "Classical Electromagnetism".

You're on the right track.

Probably way too late but what if you drilled a 1/8th or 3/16th hole from fin tip to root and then glued in a wooden dowel. Kind of like adding rebar.

Definitely not too late. So that would make a fin:

- stiffer, protecting it from a straight on landing.
- a little heavier in the back, so a little heavier rocket overall.

I think I'll be making a list of possibilities, and make a decision later. But I'll surely keep this in mind/on the list.

Using 0.75" boards, I calculate that you'll need 22.53 of them. So, if you use 23, you can sand just a little off the width of each one; that would be 0.015" off of each.

Or, use 24 of them, an even number that makes attaching the fins a lot easier. Then you'd have to remove 0.046" from each one. That's the way I'd go.

Agreed. Excellent plan.

I agree with 22.53, but the figure in fact won't be a circle, but instead perhaps a ... 24-sided polygon. Or as the smurf calls it: an icositetragon.

So I'll be trying "fit-tests" on the tube itself, just to make sure. But yes, 24 sounds like a great idea.

 

[Funkworks]

Step 17 –
The smurf said he needed a break so he could “relax by calculating the amount of bouncing power a laser shield should have, to protect a space ship from those pesky space-borne astrotermites you find in the Kuiper belt this time of year.”

Look, I don’t ask. As long as he doesn’t break anything, I let him go.

Also, he was very pleased to find out his rocket fins could double as lounge chairs and says he might try to patent that since he’s “never seen one of those that doesn’t run on smurfonium”. I just said ok.

Step 18 –
Filled in the gaps in the two-part fins. No secret formula here. Roughly equal amounts of wood glue and saw dust on a paper towel, a toothpick to mix, and an index finger to smear. A few touch-ups here and there.

Step 19 –
Sanded the dried-up home-brewed gap-filler with 40 grit. Smurf says the headgear is precisely to protect from wood dust which he says is “a substance known to the State of California to cause cancer”. When you’re his size I guess you have a different look on things.

Step 20 –
Buttered the remaining fin gaps with Elmer’s. Not sure it’s the ideal version, but it’s what I got and with a drop of water, it spreads well enough.

 

[mbeels]

This is great! Highly entertaining!

 

[Funkworks]

Step 19 –
According to the cartoon, the ladder is about 4/5 the height of the rocket fuselage, which is set here at 40 cm. That makes for a 32 cm tall ladder. Decided on 1/4” dowels for the 2 rails, and 1/10” dowels for the 14 steps. Here he is after marking the 2 rails at about 2.15 cm intervals.

 

[Funkworks]

Step 20 –
The smurf said 4 cm-wide ladder steps positioned the rails at just the right distance apart for his arms, so after marking them, he hopped on the cutters to chop off 14 ladder steps. This part looked like a lot of fun.

 

[Funkworks]

Step 21 –
I was impressed with how 56 drillings in dowels this small (1/4” diam) were accomplished without any of them causing a split. For each of 2 rails:

- 14 pilot holes (1/16” bit)​

- 14 full size holes (3/32” bit to press fit a 1/10” dowel-step).​

After a few test fits on the 1st rail, the smurf jumped up on the drill again to do the 2nd one. Although gluing the 14 steps to the 1st rail was easy, gluing the 2nd rail on the 14 ladder steps at the same time was messy, but everything was fitted and cleaned before the glue dried.

​

 

[Funkworks]

Step 22 –
Waiting for wood glue to dry in:

• the ladder
• the dummy-probe nose cone (a cheap and heavy pine version to practice making a nose cone with a lathe, before risking the real but expensive balsa version.
• a small sanding tool, to help with detailing

 

[Funkworks]

Step 23 –
Once the glue was dry, the ladder was ready to be tested. Considering the ladder to be a critical emergency component, the smurf insisted on building it and testing it himself.

 

[Funkworks]

Step 24 –
These are the brackets for attaching the ladder to the rocket:

• The 4 backing plates will be popsicle sticks, chopped to the length between ladder steps, sanded, and painted with Testor’s “Flat Steel”.
• The 4 rail straps will be insulation foam ("Climaloc Plus High Efficiency Closed Cell", 3 mm thick x 9 mm wide). This costs about $5 for 17ft. It comes in black but it’s being tested here with the same Testor’s “Flat Steel” as for the backing plates. If no smurfy chemical reaction comes out of this, everything will match, look metallic, be very light, and be stretchy enough to withstand a flight without the ladder being stressed.

Once the brackets are glued to the ladder, the assembly can then be glued, or maybe “velcro’d” to the rocket, popsicle stick (bracket) against popsicle stick (rocket surface). The foam’s flexibility should allow enough play to fit on a cylindrical or multi-sided rocket surface.

 

[Funkworks]

Step 25 –
Natural dowel color wasn’t very satisfying so I found this Minwax “Golden Oak” wood stain that seems orange enough to match the cartoon, and also fitting because oak trees are often mentioned in smurf adventures. The staining process:

• Finding a magnifying glass because the instructions are written in a ridiculously small font.
• Following the instructions, which say something like:
  • stir
  • apply stain with brush
  • remove excess with rag after 5-15 minutes
  • leave it for 2-4 hours
  • repeat to darken

i.e.: https://www.minwax.com/wood-products/stains/minwax-wood-finish

 

[Funkworks]

Step 26 –
Final sanding passes with 60 and 150 grit on the fins and discovering they might be able to serve a third function as emergency escape slides. In any case, they’re ready to be primed.

 

[Funkworks]

Step 27 –
Both the dummy nose cone and the real one, are ready for processing now. Less than $15 worth of pine and glue on the left; more than $50 of balsa on the right. Smurf said he wanted to try a JCVD-inspired photo:


I suppose I’m not the best of photographers.

 

[Funkworks]

Step 28 –
Admiring the progress so far.

 

[Funkworks]

Step 29 –
Out of the blue, the smurf suddenly made an executive decision: “Smurf the popsicle sticks!” he said. “I’m smurfing this with balsa! It’ll smurf away GRAMS of useless weight! GRAMS!”

This actually made sense, so I placed an order for 12 strips of 1/8” x ¾” x 36” balsa, as well as the 4-bladed propeller he insists on having “just in case”.

Step 30 –
Checking the original plan to make sure everything is still on track.

 

[Funkworks]

Step 31 –
Trying to decide which spring size is best. All I have at this point are these metallic ones. I can make them removable with Velcro stickers, but if anyone knows where to find plastic ones in the right size (about 0.75” diam x 1.5” tall, with 6-8 winds), I might go for that.

 

[Funkworks]

Yeah I think I screwed up the step-numbering at around 19 and 20. Don't anyone try to say it matters!

 

[mbeels]

After a few test fits on the 1st rail, the smurf jumped up on the drill again to do the 2nd one. Although gluing the 14 steps to the 1st rail was easy, gluing the 2nd rail on the 14 ladder steps at the same time was messy, but everything was fitted and cleaned before the glue dried.

Pretty impressive work for a smurf, I suppose at his size he gets pretty clever at using jigs!

Considering the ladder to be a critical emergency component, the smurf insisted on building it and testing it himself.

He needs a stunt double.

 

[dhbarr]

Step 31 –
Trying to decide which spring size is best. All I have at this point are these metallic ones. I can make them removable with Velcro stickers, but if anyone knows where to find plastic ones in the right size (about 0.75” diam x 1.5” tall, with 6-8 winds), I might go for that.
View attachment 422750

Party sized slinkies ?

 

[jqavins]

Tolerances relative to body scale should make fine work easy for them. On the other hand, the resolving power of the tiny lenses in their eyes is quite poor, which would make fine work hard. Maybe it ballences out.

 

[mbeels]

Yeah, but strength/weight to operate that power drill is something else!

 

[Funkworks]

He needs a stunt double.

At his current wage, he'll have to pay for that HIMSELF! Some of these classic ones are EXPENSIVE!

Party sized slinkies ?

I dunno. I'll have to look into what's out there.

 

[Funkworks]

Ok so in order to sort out the steps, the next one has to be 33, because I'm now keeping track of this in a separate word document and that's where it's at.

Step 33 –

Decided to go all in with the wood filler on the leading face of the 1-inch thick fins. I just squeezed some out on some cardboard, dipped an index finger in water a few times, scooped up paste, rubbed it in and let it dry.

 

[Funkworks]

Step 34 –

Sanded the filler with 150-grit paper and then a 320-grit sponge. Very smooth. NOW the fins are ready to be primed.

 

[Funkworks]

Step 35 –

Satisfactory success in the project so far got me to invest in these 1/8” x 0.75” x 36” (12 of them) balsa boards to replace the popsicle sticks. These will wrap the tube and mimic the cartoon lumber structure. Buddy quite happy about it.

Reasons:

• easy to sand laterally if they need to be narrowed (since there are so many of them and it could get tedious);
• increased thickness compared to the popsicle sticks will allow me to sand them to have the following cross-section, which is very appropriate for turning a cylindrical tube surface into a polygonal one:

 

[Funkworks]

Step 36 –

Primed the balsa boards and fins. Sanded the fins again with sponges. I finally caved and bought a whole set of sanding sponges: 60, 120, 180, 220, 320, and 800, and I’ll probably get more. They last much longer than I first thought and are easier to handle, so why not.

 

[jqavins]

• easy to sand laterally if they need to be narrowed (since there are so many of them and it could get tedious);

If you need them sanded narrower to a uniform width, you could clamp them in a stack with popsicle sticks on the sides to prevent denting them, and then sand them all at once.

• increased thickness compared to the popsicle sticks will allow me to sand them to have the following cross-section, which is very appropriate for turning a cylindrical tube surface into a polygonal one:

View attachment 424205

To ease this, I got nuthin'. Except to point out that, with a 24 sided polygon, the angle between sides is 165°, so with 3/4" wide planks the points extend only 0.025" (0.62 mm) outside of the inscribed circle. So, depending on the type of glue you're using, you may very well not need to bother profiling the planks at all.

 

[Funkworks]

If you need them sanded narrower to a uniform width, you could clamp them in a stack with popsicle sticks on the sides to prevent denting them, and then sand them all at once.

To ease this, I got nuthin'. Except to point out that, with a 24 sided polygon, the angle between sides is 165°, so with 3/4" wide planks the points extend only 0.025" (0.62 mm) outside of the inscribed circle. So, depending on the type of glue you're using, you may very well not need to bother profiling the planks at all.

To sand the profile, I plan to tape sandpaper on the tube, and a few boards as alignment guides, and then rub the boards one by one.

Narrowing them will come later. I'm still not sure about this because if I mess it up, it will leave an annoying gap. I'll see when I get there.

 

[Funkworks]

Step 37 –

This is starting to get serious. I got an aluminum 1” angle for the sole purpose of tracing 8 vertical lines on the tube, and measuring 40 cm on each one to guide the blade along a circumference.

 

[Funkworks]

Step 38 –

Testing the scale. No board is supposed to be as long as the tube, so they’ll all have to be cut to look random, and probably numbered. I think a good numbering system is NNL: where NN is a number from 01 to 24, and L is a letter from B (bottom), M (middle), T (top). So the board of top of the smurf’s head would be “01T”, and so on.

 

[Funkworks]

Step 39 –

With the rocket tube cut at 40 cm as designed, the leftover tube shown here is not only a longer backup, but it served as a support for sandpaper to have the perfect arc diameter for sanding the inside surface of each board to make them fit on the rocket tube's surface. The aluminum angle was for sanding in a constant direction, but it turned out not being very useful. Wearing a disposable cotton glove in one hand however, allowed it to press a board against the sandpaper without friction heating any fingers. The balsa was also smooth enough that splinters, in either skin or cotton, were not a concern. They easily slid along the cotton glove. The sand paper used was 40 grit and it had to be replaced 3 or 4 times.