Need Some Ideas on Making This a Reality

The Rocketry Forum

Help Support The Rocketry Forum:

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
@BABAR, I love the thought you put into mocking this out. The problem is, you speak of using trigonometry as if that is in the wheelhouse of everyone. :D It's not in mine. Ha, ha! Is there a website that would give me a template to cut out for this. I have no skills on designing this out of cardstock, especially when we're talking about the shapes with glue tabs, etc.
 

KILTED COWBOY

Well-Known Member
Joined
Jul 15, 2019
Messages
374
Reaction score
138
Location
TEXAS
You sound like a great dad. Good for you on making this rocket. I bet it will be his favorite.
Best part of this hobby, bonding with your kids.
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
Thanks @KILTED COWBOY . We've talked about making one that looks almost exactly like his drawing and then one that looks a little more like an actual stone arrowhead and feather fletching.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
No trig really required unless you HAVE to have a specific size. You don’t even HAVE to have a protractor, although it makes things easier.

I guessed at 30 degrees for the forward angle (I could make six 30 degree triangles fit into 180 degrees flat edge of advertising mailer.). Came out waaaaay too big. So I halved it, 15 degrees came out about right, dropped it to 14 to give myself overlap using a 90 degree corner of a piece of sandpaper.

Ask your son how many sides he wants. 3 is the minimum, i think over 7 is impractical.

Have him draw one long skinny isosceles triangle. Have him google it, if he doesn’t know what it is. All he needs is a ruler (metal edge is best, 6” is nice but 12” will work fine). This is your template. Decide roughly how long you want the cone to be, then use 3/4 of this for your long edge (you will eventually overlap one forward and one partial rear pyramid.

Pick a point on the middle edge of your mailer advertisement, or about a 6x9 piece of construction paper or cardstock (you can do this with regular paper but it is a bit flimsy.)

Line the apex of the triangle up with the point, and one “original long “ side of triangle with the edge, and trace the other two sides. Those would be other short side and the “other” long side.


Now move your template so the template “original long” edge lines up with the “other” long side you just drew, with the apex still at the same point. Trace the other two sides to complete triangle 2.

Keep going until you have done all 3, ,4,5,6, or 7 triangles, all sharing the same apex of tip point.

Use the back side of your blade to “score” the long lines (or just go over them really heavy with a ballpoint pen). You do NOT want to cut it, you just want to dent it so it is easy to fold.

Cut it out and fold it up, use a piece of tape to attach the free edges.

Compare the result to your Father’s Day card, or his imagination, and to the size of your rocket body tube.

How’d you do? Is it too squatty? Try a narrower apex angle. Too thin? Bigger Apex angle. To small? Make sides bigger. You get the point (literally!). Here’s where a protractor helps you out, because once you know your angle, you can use the protractor to Mark all the sides for you, then you draw your lines (go too long, then just measure and mark the right length on each line)

Once he is happy with the number of sides, the angles, and the length, make a copy of THAT triangle template.
Then cut off the top (apex) 2/3, leaves you a base trapezoid.
Put this aside.

Use your original temple (or better yet, the protractor) on your card stock to draw out your forward pyramid on a new piece of recycled card stock, but DON’t cut it out.

Use your trapezoid template, line up the base with the base of each of the triangles you just drew on the cardstock. You can do this better if you use the protractor to draw a straight line lightly in pencil down the middle of each triangle (“bisecting” each one and put a mark on the middle of the long and short [top and bottom] of your trapezoid.). Draw a trapezoid opposite each triangle (so the triangles and the trapezoids share the same “base.”)

Now “score” the fold lines, these will be the sides of the triangles and the BASES of the triangles. Do Not Score the bisecting lines.

Now cut it out, the only lines you should be cutting are the sides of the trapezoids and the short ends.

Fold it up and tape the long free edges of the two edge triangles and the short sides of the two trapezoids.

How’d you do? If base is too short, try it with only 1/2 of the template cut off instead of 2/3.

You CAN also use different angles for the base trapezoids if you want a squatter or longer lower pyramid section, but you have to use the same size trapezoid base to match the triangles.

Hopefully part of the fun is TRYING different numbers of sides and different angles and sizes. My first helicopter had a three sided pyramid (search for GYSKELION under BABAR) and I was thrilled with it. Your son can also make his own triangular or square or pentagonal (and so forth) body tubes to match his nose cones. For low power rockets, about the only thing you probably should buy are motor mount tubes (although you can roll those yourself, I prefer “real” store bought tubes.). So get some BT-5s, 20s, and 50s. You can make centering polygons out of foam board, and get balsa sheets at local hobby store for fins. Paper sodas straws work great for launch lugs, they are hard to find at most fast food places but are pretty cheap on Amazon, I bought a box for a few bucks a few years ago and it is still over half full.

Be safe and HAVE FUN,
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
When you finally have a size you like, draw it on a new piece of card stock, score it but don’t cut it out.

Flip it over and use sandpaper or colored duct tape or whatever you can imagine to decorate the “outside.”

Now cut it out and use tape or glue an overlap on the INSIDE.
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
@BABAR Thanks so much for all your help with this. I'm pretty sure I can follow your directions and make this with my son. It's also stuff that he can do most of the tracing, cutting and glueing. Your method is one that will allow us to make a nosecone that looks exactly like this drawing. We'll probably use one of the balsa methods to do a version of a traditional arrow. I'll make sure to post pics of the process. I've got plenty of the other building materials for the rest.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
@BABAR Thanks so much for all your help with this. I'm pretty sure I can follow your directions and make this with my son. It's also stuff that he can do most of the tracing, cutting and glueing. Your method is one that will allow us to make a nosecone that looks exactly like this drawing. We'll probably use one of the balsa methods to do a version of a traditional arrow. I'll make sure to post pics of the process. I've got plenty of the other building materials for the rest.
Great!

A minus (and plus!) of paper nose cones is that they do not survive ballistic recoveries well. I say that is in a way a plus, because most nose plastic and balsa nose cones don’t do well with ballistic impacts with asphalt and concrete And maybe playa del California, although they may do okay wit grass or soft dirt. So the plus is that these are much easier and cheaper to replace.

But the other plus is safety. Although a ballistic recovery (aside from Mosquito,Quark, and other featherweight recoveries) is never excusable, stuff happens. Paper nose cones are like the new car “crumple” zones, so if they hit something the paper crumples and the force is basically spread out to the width of the body tube or nose cone base. Not that, aside from the above, ballistic recovery is EVER safe, but if it’s gonna happen, I’d much rather get hit with one of these than a typical ogive plastic BT-20 cone.

You can reinforce the internal structure of these with heavy duty cardstock or balsa or plastic key card triangles cut just a bit smaller than your template and glued on inside before folding (although I have never needed to, if after a few flights the tip gets a bit distorted, I just make another. Mine are reinforced AND attached to tube with Mylar tape. Strength AND shiny color.....win-win! So swapping out used for new is easy enough. )

If you make them long and skinny, you can stick a bit of clay in the nose—— the added LENGTH makes a minimal mass go a looooong way is affect on CG.

I haven’t tried filling them with polyurethane glue, I am afraid the expansion would likely distort the contours.
 

Rktman

Eric
Joined
Mar 5, 2017
Messages
1,013
Reaction score
71
Great!

A minus (and plus!) of paper nose cones is that they do not survive ballistic recoveries well. I say that is in a way a plus, because most nose plastic and balsa nose cones don’t do well with ballistic impacts with asphalt and concrete And maybe playa del California, although they may do okay wit grass or soft dirt. So the plus is that these are much easier and cheaper to replace.

But the other plus is safety. Although a ballistic recovery (aside from Mosquito,Quark, and other featherweight recoveries) is never excusable, stuff happens. Paper nose cones are like the new car “crumple” zones, so if they hit something the paper crumples and the force is basically spread out to the width of the body tube or nose cone base. Not that, aside from the above, ballistic recovery is EVER safe, but if it’s gonna happen, I’d much rather get hit with one of these than a typical ogive plastic BT-20 cone.

You can reinforce the internal structure of these with heavy duty cardstock or balsa or plastic key card triangles cut just a bit smaller than your template and glued on inside before folding (although I have never needed to, if after a few flights the tip gets a bit distorted, I just make another. Mine are reinforced AND attached to tube with Mylar tape. Strength AND shiny color.....win-win! So swapping out used for new is easy enough. )

If you make them long and skinny, you can stick a bit of clay in the nose—— the added LENGTH makes a minimal mass go a looooong way is affect on CG.

I haven’t tried filling them with polyurethane glue, I am afraid the expansion would likely distort the contours.
Some expanding foam squirted into the paper cone would serve to safely reinforce it as well as give the cone's shoulder something to seat against. Just be conservative with the amount squirted in, the excess will expand out the cone's open end so there shouldn't be much pressure against the sides.
 
Last edited:

kbRocket

Well-Known Member
TRF Supporter
Joined
Nov 14, 2017
Messages
56
Reaction score
37
Location
Portland, OR
Five minutes after reading your post I walked into the living room to find this on the floor:
stuffers.JPG
Looks like it is made for about a 20 mm air frame and already includes the nose weight required for stability.

I once had good luck making a nose cone out of paper mache applied over styrofoam that was later removed.
 

kbRocket

Well-Known Member
TRF Supporter
Joined
Nov 14, 2017
Messages
56
Reaction score
37
Location
Portland, OR
There is a shareware program called poly http://www.peda.com/poly/ that can show many different polyhedrons both in 3D and a flat view. You may be able to use it to get ideas and producing templates for making multi faceted nose cones.
1593705677835.png 1593705716872.png

Or you may just want to look at cool shapes and how they can be made.
 

rklapp

NAR# 109557
TRF Supporter
Joined
May 8, 2020
Messages
387
Reaction score
209
Location
Oahu, Hawaii
On a somewhat related topic, I was watching a video about Skunkworks. Someone found an obscure Russian paper on aerodynamics and decided to try and create a stealth airplane from the 60's era formulas. The result was the F-117, but the reason why it has straight lines is because in the 70s, they didn't have the computer processing power like they have now to calculate curved edges such as the F-22 and F-35.
 

OverTheTop

Well-Known Member
Joined
Jul 10, 2007
Messages
3,834
Reaction score
1,150
Location
Melbourne Australia
On a somewhat related topic, I was watching a video about Skunkworks. Someone found an obscure Russian paper on aerodynamics and decided to try and create a stealth airplane from the 60's era formulas. The result was the F-117, but the reason why it has straight lines is because in the 70s, they didn't have the computer processing power like they have now to calculate curved edges such as the F-22 and F-35.
Yep. By using straight edges the computer program could be run overnight and they could quickly iterate the design towards a low radar cross-section. Their program was heavily optimised also, which made this possible. Computers back then didn't have the memory or processing capacity to do complex things quickly.

This is a good book on it if you are interested: https://arc.aiaa.org/doi/book/10.2514/4.867958
4170GGJDNSL._SX312_BO1,204,203,200_.jpg
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
Here he is cutting out a prototype and the "finished" prototype. It fits perfectly on a BT-20. I will be posting a separate build thread to show the whole process. Thanks especially to @BABAR for the ideas. @kuririn, we'll be using a coupler to make the nosecone as you suggested.
The rest of you, we're planning to make another version that is shaped more like an actual native american arrowhead and with natural style fletching. We'll be using the balsa ideas suggested above. This thread has been amazing and I appreciate all your help and encouragement. My son must have told me half a dozen times how much he loves doing this with me. Can't buy that with money!
IMG_4135.jpeg
IMG_4136.jpeg
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
@BABAR, we used your idea of the 14 degree angle. The triangle is 2" and the bottom is half that. When it came together it was perfect for a BT-20. I would have liked to do one to fit a BT-5 but that would be a tad too fiddly for his young fingers and my fat ones. As the goal of this one was replicate the Father's Day card he made for me this design idea couldn't be more perfect. He was concerned with the crush factor but I told him that's why we'll make three or four nosecones, and if we crash it we'll make it again. I have loads of old file folders laying around. I might use some thin CA to strengthen it a bit too.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
Here he is cutting out a prototype and the "finished" prototype. It fits perfectly on a BT-20. I will be posting a separate build thread to show the whole process. Thanks especially to @BABAR for the ideas. @kuririn, we'll be using a coupler to make the nosecone as you suggested.
The rest of you, we're planning to make another version that is shaped more like an actual native american arrowhead and with natural style fletching. We'll be using the balsa ideas suggested above. This thread has been amazing and I appreciate all your help and encouragement. My son must have told me half a dozen times how much he loves doing this with me. Can't buy that with money!View attachment 423462View attachment 423463
That smile made my day,errr.... rather night since I work nights! Thanks for letting me play a part in this.

I don’t want to give too much input, it IS HIS project. Options for reinforcement include gluing smaller triangles and trapezoids INSIDE the internal matching polyhedrons, made out of heavier cardstock or thin 1/16 balsa (basswood is stronger but much more difficult to cut with a blade. Besides, paper glued to balsa, even 1/16 inch, is plenty strong.). If you do this with balsa, glue all the pieces at the same time, stick it in folded wax paper or even better parchment paper, and stick it in an old book with some weight on it. The balsa will tend to curl away from the paper otherwise.

You can also decorate/color the outside by applying your coloring or tape on the outside. This can be done either before or after you cut out the pattern.

Joann fabrics has a duct tape color, “cookie dough” that might work for you. Putting it on before you cut it out will be easier, will be stronger, and you can use a small external piece if needed to seal the seam, given it is the same color may not be too obvious.

For me, using Duct tape as a structural part of the rocket is just plain fun. Using tape named “cookie dough” is icing on the cake! BTW, duct tape may not have played a role in Native American history, but it did save Apollo 13’s bacon (also Hanks and Paxton, but only in the movie version,)


Something to TRY, MAYBE use a black sharpie along the edges of the finished shape to accentuate the edges, try this on some scrap first to see if you like the effect,

Keep having fun!

 
Last edited:

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
A heads up. Because the nose cone is wider than the body tube, your standard launch lug placement won’t work.

You have a few options.

1. Put a “standoff” rectacular balsa piece (cut so the grain is perpendicular to the long axis of the tube. This is a bit tougher cut, but much stronger) and move the lug away from the rocket body enough that it clears the nose cone

2. Put the lug on the side of a fin, again away from the body tube enough to clear the nose. This is the easiest, but structurally the most stressful, as it is usually far off the CG and the CP, so more likely to break if the rocket is on the pad for a while due to the wind blowing the rocket around on the rod, also more likely to bind of launch as it is away from CG.

3. Run a parallel hole with a straw or lug THROUGH the nose cone (do it on the back or least “cosmetic” side. This is the hardest one to dio, it is the least cosmetic (not a big deal if you don’t mind having a blemish on the “back side” of the rocket), and you have to take a moment to make sure this is lined up with your main Body tube lug. I used it for the Tank Killer and was really pleased with it,


See post 1 pic 3

 

kbRocket

Well-Known Member
TRF Supporter
Joined
Nov 14, 2017
Messages
56
Reaction score
37
Location
Portland, OR
You may look into Modge Podge as both a stiffener and a finish. Besides being safe and age appropriate, it works well on paper. My son has been using it lately in paper/card stock creations. It makes them stiff and shiny.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
You may look into Modge Podge as both a stiffener and a finish. Besides being safe and age appropriate, it works well on paper. My son has been using it lately in paper/card stock creations. It makes them stiff and shiny.
Also, when you make the cuts, you can actually cut only one side of the triangles between the trapezoids to use as a glue tab on the inside (for the other side that you would normally cut, just SCORE it and it will fold nicely.

My card stock noses have held up pretty nicely, although now my Helis and AirBrakers land nose up rather than nose down, so that helps.

If your rocket is LONG enough (and I am thinking anything ARROW like should naturally BE relatively long) you don’t need any nose weight. That means much less landing stress. Knock wood (or cardstock), I have yet to have an AERODYNAMIC failure of any of my nose pyramids, most of which have been four sided. The max motor I have used is an E.

So the if you use a long body tube (I am thinking at least 18”), just put a shoulder at the base filled with enough polyurethane glue to hold a screw eye, your nose cone should last a while (especially if you cover it with duct tape ;) )
 

rklapp

NAR# 109557
TRF Supporter
Joined
May 8, 2020
Messages
387
Reaction score
209
Location
Oahu, Hawaii
Also, when you make the cuts, you can actually cut only one side of the triangles between the trapezoids to use as a glue tab on the inside (for the other side that you would normally cut, just SCORE it and it will fold nicely.

My card stock noses have held up pretty nicely, although now my Helis and AirBrakers land nose up rather than nose down, so that helps.

If your rocket is LONG enough (and I am thinking anything ARROW like should naturally BE relatively long) you don’t need any nose weight. That means much less landing stress. Knock wood (or cardstock), I have yet to have an AERODYNAMIC failure of any of my nose pyramids, most of which have been four sided. The max motor I have used is an E.

So the if you use a long body tube (I am thinking at least 18”), just put a shoulder at the base filled with enough polyurethane glue to hold a screw eye, your nose cone should last a while (especially if you cover it with duct tape ;) )
With the feather fins and the mod podge on the cone, a string test would be interesting.

I’m also curious which lug option(s) you choose.
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
With the feather fins and the mod podge on the cone, a string test would be interesting.

I’m also curious which lug option(s) you choose.
I should have made myself more clear, we're not using actual feathers. We're going to make them feather-like, out of balsa. They'll be swept back, much more than an actual arrow would be because we're trying to duplicate the arrow from the photo in post one. I'm assuming the swept back design will also add more stability to it. I hope.

I'll be using a stand off for the lug.
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
Also, when you make the cuts, you can actually cut only one side of the triangles between the trapezoids to use as a glue tab on the inside (for the other side that you would normally cut, just SCORE it and it will fold nicely.
Thanks for that great idea. I'm new to folding cardstock. Is there a particular glue that is preferred for glueing the tabs? I've got all the "traditional" glues, i.e. white glue, ca, etc.
 

rklapp

NAR# 109557
TRF Supporter
Joined
May 8, 2020
Messages
387
Reaction score
209
Location
Oahu, Hawaii
I should have made myself more clear, we're not using actual feathers. We're going to make them feather-like, out of balsa. They'll be swept back, much more than an actual arrow would be because we're trying to duplicate the arrow from the photo in post one. I'm assuming the swept back design will also add more stability to it. I hope.

I'll be using a stand off for the lug.
Sorry, I meant to say feather-like fins. They look like they have significant weight but should be offset vertically by the mod podge or whatever weight you put in the card stock cone. :)

You could do both stand-off and lug attached to the fin.
 

markschnell

Well-Known Member
TRF Supporter
Joined
Feb 10, 2009
Messages
200
Reaction score
65
Location
Marion, Indiana
Sorry, I meant to say feather-like fins. They look like they have significant weight but should be offset vertically by the mod podge or whatever weight you put in the card stock cone. :)

You could do both stand-off and lug attached to the fin.
Ahh, got it. The fin lug and stand-off is a good idea. Thanks.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
Thanks for that great idea. I'm new to folding cardstock. Is there a particular glue that is preferred for glueing the tabs? I've got all the "traditional" glues, i.e. white glue, ca, etc.
Everything I have read and from my experience good white glue (real Elmer’s or Aleene’s tacky glue, NOT Elmer’s School Glue) is the glue of choice for paper to paper and paper to cardboard. I use it also for LPR motor mounts, has just as much strength as wood glue for paper to paper or cardboard and a longer “set” time, so it doesn’t “grab” too soon, with mount only partly inserted.

Double glue joint still works for paper, apply a thin bit complete coating to both surfaces (squeegee it off, or wipe it down off with a finger, then wipe your finger on a damp towel.). Let both surfaces dry for three or four minutes, then pinch them together.

The tough part is NOT getting glue on the outside surface, it is really hard to get it off and it messes up the finish.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
Found this in an article.

The point is secured in the notch with sinew and pitch (or glue). Native peoples used sinew for permanent nonflexible bindings. Sinew was obtained from deer, elk, or bison tendons that were harvested from freshly killed animals and prepared, dried, and stored for later use. Narrow strips of sinew were softened in water, applied wet as a binding, and allowed to dry tight. A modern substitute is 􏰂artificial sinew,􏰃 available at most hobby and craft stores. It is best described as nylon dental tape that has been impregnated with a colored wax, and flat 􏰂artificial sinew􏰃 works better than round sinew for arrows.

Full article here


 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,953
Reaction score
1,329
I have had good experience getting Kevlar from this vendor

 
Top