Eye Catching Design - Launch

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les

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I've got an idea for a scratch design that I think will be somewhat eye catching

The design is not 100% complete, so some changes will occur during the build...

The basic concept looks like this. Note - the rocksim file is not complete. I just wanted to get a general idea on the stability

Eye Catcher.jpg
 

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I like it :) Love sharp, pointy things. Be sure to use an extra long shock cord. Parachutes like to tangle with sharp, pointy things ;)
 
Here is a picture of the parts.

BT50, BT55, BT60, 2.75" tubes

BBQ skewers (wait - what? BBQ skewers???)

BT5060 centering rings, kevlar cord

4 nose cones, ping pong balls (no - I am not channeling Shrox), 24mm retainer, basswood for fins.

Not shown is the foam board for centering rings, card stock for the transitions, and elastic shock cord

parts.jpg
 
Ooooh! I like your style. I have something similar, and I don't have a finish photo, but it's going up in a couple of weeks. I call it, Dorian's Revenge. It's the one on the right.

100_0952.jpg
 
The small (short) rings will be cut to fit inside the with gaps for the skewers

internal ring.jpg

Decided to dry fit/ lay out some of the parts together

dry assy.jpg
 
I made a couple of design changes. I made the bottom 2.75" section longer to get more support with the BT60 centering rings. I also increased the length of the main BT60 tube to have more room for a parachute.

I concentrated on the top portion. As previously shown I have 2 sections of 2.75" tube plus two small sections cut down to fit inside, plus a solid bulkhead.
I marked the appropriate depth, added a glue band, and used the small ring to push the bulkhead in.

internal 1.jpg internal 2.jpg internal 3.jpg

I created a marking guide for 12 skewers

The first is installed

support 1.jpg

I then did the opposite then the two at 90 degrees, then added all the rest until all 12 were installed. The upper rings are not glued at this point - they are just being used to help support the structure. I did reduce the skewer length for strength

support 2.jpg
 
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I used the technique from the Apogee newsletter for a super shroud. I made two of each and then glued them together. Here they are drying on a piece of BT60

transition.jpg

I cut down the BT60 and dry fit it all together again

dry fit 2.jpg
 
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Some more work on the skewers

Two details added
Using kevlar cord and an over/under threading I added some detail at the midpoint of the skewers

skewer cord.jpg

I found the gaps between my inner and outer rings ugly, so I cut out some card stock and glued them between the skewers.

skewer fill 1.jpg skewer fill 2.jpg
 
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Now some work on the pods

Using the BT55 tube as a guide, I cut out some landing pods from the ping pong balls. I also cut some short lengths of the BT55 and slit them so they fit inside

pod parts.jpg

Then using epoxy (both to have more working time and to grab the ping pong ball material), I put a bead inside the BT55 tube and on the edge of the cut BT55
I then pushed the ping pong ball on and pushed down. Using the cut tube provided an extra area for the epoxy to grab

pod assy 1.jpg pod assy 2.jpg

Some paint can tops helped support the tubes while the epoxy dried.

pod glue.jpg

And then some cutting and sanding to get the ping pong ball even with the tube. So now we have a landing pad on the end of the out-rigger pods

pod final.jpg
 
definitely no decals of anyone in drag!!!! :y:

Glued the out rigger pods onto the main fins. These are through the wall. I also added a bit of 2 part expanding foam to strengthen the ping pong balls (sorry - landing pads) and its attachment

pod fin 1.jpg pod fin 2.jpg pod fin 3.jpg

The motor mount was built and installed

motor mount.jpg
 
The transitions and structure are built.

I had a brain fart when I made the main fins. The tabs were cut way too long (like able to meet in the center - duh). After cutting them down to size the extra pieces were just the right size to strengthen the lower transition structure. With the "cage" assembly (as Afterburners called it) the top is somewhat heavy. I tied Kevlar cord for attaching the shock cord. I strengthen the top using a coupler section and soaking it with CA.

trans 1.jpg trans 2.jpg

I also tried a coupler for mounting the top to the bottom (where the chute will come out). It was a bit too wobbly for my tastes. I had a piece of BT60 leftover that I cut in half, slit, and made into a longer coupler. Used the other half to make a second layer. This shows my coupler vs the purchased one

trans 3.jpg
 
Glued up the transitions and then did some cleanup of the edges with some F&F

upper FF.jpg

Back down to the pods/fins

Added "flanges" to the main fins at the pod. And then used a dremel to shape. A before and after picture...

pod flange.jpg

While the pod to the main fin I made fairly bullet proof, I figured the spikes would be sacrificial (subject to damage). I used 3/32 balsa vs the 1/8 basswood for the main fins

Added two spikes and then flanges to each spike

spikes.jpg spike flange.jpg

I also had to trim a slot in the nose cones to clear the fin

nose cone.jpg
 
Using masking tape, I did another dry fit

dry fit 3.jpg

I need to make a few decisions.

Originally, I was going to use the 18" BT60 for the base and the transition, but decided it would be too short. So I used another piece for the transition. Now I think the base BT60 is too long. I'm thinking of cutting 2~3 inches off.

I also have to figure out the launch lug. With 2.75" tube, I have to move the lug out. I see 3 options
1) - glue the lug to a fin
2) - add a single stand-off between fins just for the lug
3) - Add three strakes to be symmetrical (one of which will just happen to have the lug attached). But I am concerned it will take away from the pod. As some say - less is more

And color scheme. Thinking of a hammered black with red trim on the edges of the fins and spikes
 
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my two cents... i would not take more than an inch off of the base BT. if it is too long it is just slightly too long. 2 or 3 inches would make it too stubby IMHO. plus that space could be well utilized. add some details in there, maybe some small forward facing pointy bits or just some soft decals (like a wide band then a space then a slightly less wide band and a less wide space to a narrow band then narrow space and so on for about 5 or so steps) to tie it together. I think it looks absolutely fantastic!

And ditch the LL this baby needs a tower!!!!

And as for color scheme i think you are right on but i would use a royal blue/ laser blue for accents!

ok maybe that was 3 cents worth but who is counting... :)
 
Not much today. Dealing with our garden tractor going kaput as well as our microwave. Been a bad couple of weeks. Exercise bike also failed, daughter's car broke to the point of only good for scrap, son's car broke but was repairable (for over $2000) - all very expensive

I did do the Dremel on the spike flanges and a coat of F&F. No pix at this time

And a bit of a scare as I was accidentally banned from TRF! Fortunately got it all squared away and I'm BACK!
 
Does this look familiar

ImageUploadedByRocketry Forum1405968119.062456.jpg


So many rockets, so little time, and money.
 
Gluing the fins on

fin jig.jpg

Some other views after the fins were on

spike closeup.jpg top view.jpg

Adding the flanges. Used angle aluminum to get the flanges in line with the fins

flange.jpg flange angle.jpg
 
OK - I blew it :facepalm:

The main fins are just too bloody flexible. With the pods and spikes there is too much mass. I probably should have used plywood for the fins to start with.

So what do I do now?? :confused2:

First thing I tried was to glue a dowel to the trailing edge of the fin

fin dowel.jpg

Some improvement, but still not good enough. While the base of the fin is a little more stable the top can still flex.

I have some 1/16" plywood. I'm going to make panels for each side of the fin and epoxy them on.

I am going to make the panel a different size to create some more texture. Here is a panel just sitting on the fin - not glued yet

fin panel.jpg

When I said this was going to be a design in process I did not expect this.....
Well - hopefully learn from my mistakes...........
 
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