| Model Rocketry Project : How To Make Your Own Nose Cone|
It was time to build a bigger rocket and by now I was heavily into scratch-building.
To work around this, some form of guiding system would need to be included in the process.
This would greatly increase the odds of ending up with a usable nose cone.
The Quik Tubes (used to pour cement pillars) always looked interesting to me. They are found
at local hardware stores (no shipping) and are cheap, about $6 or a 4 foot section.|
The main challenge would be my complete lack of artistic ability. Simply trying to convince a
piece of foam to take on the shape of nose cone wasn't going to work.
Follow this process you and should end up with a nose cone that looks pretty decent. Mine came
out less than perfect, but far better than expected for a first attempt at making a nose cone.
A success overall.
The main "trick" is to take your time. Don't try to rush things. Especially when shaping the foam.
- blue foam (3/4" thick, found at Lowe's)
How to make the nose cone
- 1/4" plywood
- carbon rod
- coupler (or tube to make coupler)
First, you need a rod or dowel that is very stiff and won't bend easily and won't deform at all. As I had a piece of carbon fiber rod around, I figured that would do nicely.
Please make sure the diameter of your rod matches that of the hole drilled by the pilot hole of your hole saw. Mine didn't quite match and some flaws in the cone are due to this. Obviously, the rod needs to be long enough, a bit longer than the length of the nose cone.
Start by making a stand for the rod. This will keep the rod vertical while the nose is being build. I took some squares of 3/4" thick ply and glued them together.|
What you see here is a printout from RockSim. You can use any
other software, or if you have the talent, draw the nose cone yourself.|
As this is a larger nose cone, it had to be printed on several sheets of paper which were taped together.
The first circle to be cut has to have the same diameter as where the nose cone meets the body tube.|
If you are going to fiberglass the body tube, take this measurement before you apply the fiberglass. The cone will end up slighly larger in diameter than this disc, as it will be fiberglassed.
Now make a line 3 1/4" away from the area where the nose cone meets the body tube. Cut the next
disc/circle to be this size.|
Make a mark 3 1/4" from the previous mark and cut the next circle. Repeat this until you get to the tip of the nose cone.
Place the first circle (the one where the nose cone meets the body tube) on the stand.|
Cut four sections of blue foam, each larger than the bottom plywood disc. Slide them onto the
rod. These were glued onto each other with some epoxy|
Slide on the next plywood disc.
Quick note on the foam, it has a layer of clear plastic film on one side, remove that first.
Repeat the above step. Put 4 layers of foam onto the disc and put the next disc in place.|
Continue this until you have used all discs.|
Please take your time doing this. Wait until the epoxy dries for each layer (two discs + 4 foam sheets).
I didn't and things started to shift a little towards the end, which introduces flaws into the shape (especially if your rod doesn't quite match the pilot hole size).
And here too, my impatience was showing. I couldn't wait to start shaping the nose cone. This was done in the evening, which made for bad lighting for pictures.|
First, I used a hack-saw to remove the corners from the foam.
Next, a rasp (found in hardware store) was used to shape the foam. This leaves the surface somewhat rough, that's OK.|
This is where the guiding system, the wooden discs, help a lot. This will ensure, to some
degree, that you don't remove too much foam. Shape the foam in broad strokes, from the tip of
the nose, down to the shoulder. Take your time.
A hand sander left the surface nice and smooth.
The following morning, it was time to fiberglass the nose cone. I used 3 layers of 6 oz glass which was too much. Two layers would almost certainly have been enough.|
The nose cone print-out was cut out, with about 3/8" border around it. This will make it so 3 pieces will nicely cover the cone with minimal overlap.
The circumference of a circle is equal to the diameter times pi and pi is roughly 3.14. In other words, we'd need 3.14
printouts to cover the cone.
If we used 3 printouts, that would leave us .14 short. The tube diameter is 7.75". The missing
piece would be 7.75 x .14 = 1.085". Spread that over each of the 3 pieces : 1.085/3 = 0.362. That
0.362" is divided in two (one half on each side of the printout), which means we'd need 0.18"
of border (around nose cone shape) on each fiberglass cutout if we wanted no overlap at all.
I used a 3/8" border on each side of the nose cone printout which allowed for some overlap to make for easier fiberglass application.
This picture shows the rocket's nose cone with the fiberglass curing.|
When you apply the fiberglass, remove the cone from the stand.
To keep the fiberglass wrapped around the bottom of the nose cone, I cut another plywood
disc equal in diameter to the body tube diameter (7.75"). It was wrapped with Seran wrap, so epoxy
won't stick to it.
This Seran wrapped disc was slid onto the rod at the bottom of the cone.
Put the nose cone back onto the stand when done fiberglassing (for each layer). That extra disk squeezed the fiberglass at the bottom
of the cone in place and makes it so it won't stick to the stand.
The shape was bumpy here and there, so the whole thing was covered in filler, SuperFil in this case.|
As shown here, most of the filler has been sanded off, but it needs some more sanding.
Any remaining dips were filled with Bondo spot filler.
Let's make the nose cone's shoulder. For this, we'll need a coupler. As I was working with
Quik Tube, one had to be made.|
The tube you see with a section missing will be glued inside the coupler, to reinforce it. This
is shorter than the coupler, it sits between two bulkplates.
First, a bulkplate was glued into the bottom of the coupler. The reinforcement tube was
glued on top of it (inside the coupler), followed by the other bulkplate.
Attach a U-bolt, or similar, to one of the bulkplates. This will be used for shock-cord attachment.
Simply slide this assemble over the rod at the bottom of the nose cone and epoxy it in place.
Here is the assembled nose cone, before any primer and paint.|
All in all, it came out OK. Not perfect at all but good enough for a first attempt at
a homemade nose cone.
The below video shows an early ground test. At this stage, parachutes had not yet been
included in the test. The result was not bad, but the charge needs to be increased.
Video : Ground test