Scratch build "Veeatrice" with pancake av-bay

[Adrian A]

The new Blue Raven altimeter that's in development can be launched with any electronics orientation, so for larger diameter rockets, it opens the possibility of mounting them flat to reduce the av-bay length. I'm working on a new av-bay mounting accessory, similar to the Featherweight Power Perch, but designed around flat-mounting redundant Blue Ravens in a 0.5" long av-bay cavity.

But I don't have a 4" rocket to test this out in, since I'm more of a MD guy, so I decided to try building something new for me. Basically I want to fly a very short av-bay (~ 1" long with hardware and bulkheads) in a fun way, so I decided to make a dual-deploy HPR rocket that's almost all nosecone and boat tail.

Apogee has some nice long, slender 4" nosecones, so I'm designing around 2 of them:

 

[Adrian A]

I have some Blue Tube from years ago that I never used, so that's getting put to use for the coupler and short body tube.

I cut off all but 3/4" of the nosecone shoulders and I'm going to glue on body frame tubes on both sides. I cut the coupler and 2 body tubes a little longer to make the coupling a little more stable:
I trimmed the end off of the boat tail by first going at it with a dremel with a cutting wheel and then I used tin snips to spiral-trim the end until I could just push the motor mount tube through the end.



A foam core fin jig is holding the fins that I cut out of some CF mostly-unidirectional sheet stock I had left over.

I JB-Welded the fins onto the 38mm motor mount tube and so I'll let that cure and come back to this tomorrow.

 

[mtnmanak]

Adrian - If you are looking for a test bed, I have 2 x 8" diameter projects and a 9" diameter project ongoing with a 12" diameter project scheduled for the fall (all of them fiberglass construction). I would be happy to design all sorts of eclectic AV bays for any or all of the projects to meet your test needs.

 

[Adrian A]

Adrian - If you are looking for a test bed, I have 2 x 8" diameter projects and a 9" diameter project ongoing with a 12" diameter project scheduled for the fall (all of them fiberglass construction). I would be happy to design all sorts of eclectic AV bays for any or all of the projects to meet your test needs.

That's a kind offer. The goal of these av-bays is to make it so no design work is required. You just glue in 1 ring into your coupler near one end and then you don't have to wire anything. But I'll DM you with more information about attachment hardware, etc, to see if I'm on the right track.

 

[Adrian A]

The garage was hot enough that the JB Weld cured in time for me to make some more progress:

Fun to see the final shape!

After the test-fit and cutting I went back to put fillets on the motor mount-fin attachment:

 

[Adrian A]

I figured out a way to ensure that both ends are cones straight with each other when I glue the airframe extensions on. I have a 1.5" diameter aluminum tube that I have used as a composites mandrel, and it goes through the motor mount all the way to the front of the nosecone. Shown below is the tailcone, fins, motor mount tube with the mandrel sticking out of it, and the tailcone aiframe extension and coupler.
I cut out a foam core jig to keep the front of the motor mount concentric with the tailcone, and then the aluminum mandrel sticking past it into the tip of the nosecone keeps the nosecone aligned straight. You can't see from the photo, but I printed the right size concentric circles on the other side of the foam core jig.


Here I put in the coupler and JB-welded the two airframe extensions onto the two cones.

Unfortunately, when I glued this together I had to rush off to drop someone off at the airport, and I didn't notice that I didn't have the airframe extensions pushed up against each other so that the airframe/airframe joint was flush. The tailcone airframe extension is a little crooked, so when the mandrel is aligning everything straight, there is a little gap on one side of the airframe joint:

It's hard to see in the photo, but it's about a 1 mm gap. By rotating the halves against each other and seeing where the gap moves, I could tell that the problem was all on the lower half. So I cut into the airframe extension and ripped it off of the tailcone. It came off a little easier than I was expecting. Next I'll cut a new tailcone airframe extension and try again to bond it on straight.

 

[Adrian A]

I re-did the tailcone airframe extension and got it right this time, so I moved on. Here are a bunch more build photos:

Threading the aft recovery harness through the fin can so it's not just relying on the centering ring bond to the airframe

Sanded the inside of the tailcone where the centering ring will go

A little hard to see here, but I cone-ified the centering ring so it would seat down farther. I really buttered it up before installing.

Yet another foam core alignment jig keeps the motor tube centered in the airframe

Test fit with the centering ring and aft recovery harness before the glue

Good thing the tailcone plastic is flexible. It made this part a lot easier.

Gently squeezing the tailcone petals down to the end of the motor tube

 

[Adrian A]

Today I installed the rail buttons. I'm trying something a little unorthodox, which is to use 2 adjacent sides of the rail, so that I can use a fin for the aft button:




Currently the weld nut is visible on the other side of the fin. I may come back later and cut off the threaded part of the weld nut and install another button on the other side just for aesthetic and aerodynamic symmetry.

Since the forward rail button is offset 0.5" from center, I needed to install it at an angle to the tube. Here I put it on the joint between the airframe and tailcone, with a little wedge-sanded piece of basswood to angle the weld-nut appropriately:

 

[jmasterj]

Very cool idea!

 

[Adrian A]

I sanded down the high spots on the Blue Tube airframe extenders. Today I did the fin fillets and covered the cylindrical section with some laminating resin mixed with colloidal silica to make a sort of gel:

The vacuum bagged stuff is for another thread.

I'm not sure how smooth I'm going to be able to get the cones. They are currently quite rough wherever I have done any sanding. I have some sandable primer I will probably use liberally when the time comes. The paint scheme will be silver for the body (as shiny and mirror-like as I can get, which I'm not optimistic about) and leave the fins as clear-coated carbon.

 

[Handeman]

I have some sandable primer I will probably use liberally when the time comes. The paint scheme will be silver for the body (as shiny and mirror-like as I can get, which I'm not optimistic about) and leave the fins as clear-coated carbon.

The sandable filler primer is a good idea. It's the only thing I use because I can sand the high spots and let it fill in low spots so I get a better smoother finish.

I used "Chrome" spray paint once. It really did look like chrome, very miror-like and shiny. At least until I touched it without a glove. Unlike real chrome, I couldn't clean fingerprints and smudges off of it. I ended up repainting with a silver paint. Not as shiny, but looked much better for much longer.

 

[Adrian A]

The sandable filler primer is a good idea. It's the only thing I use because I can sand the high spots and let it fill in low spots so I get a better smoother finish.

I used "Chrome" spray paint once. It really did look like chrome, very miror-like and shiny. At least until I touched it without a glove. Unlike real chrome, I couldn't clean fingerprints and smudges off of it. I ended up repainting with a silver paint. Not as shiny, but looked much better for much longer.

Yeah, that's the stuff. I was also noticing that on a test spray of pieces I cut off of the nosecone base. A fingernail mars it really clearly. I was thinking about putting a clear coat over it

 

[waltr]

I use Createx Quicksilver over their Gloss black. This produces a very nice chrome or polished aluminum that is durable.
https://spraygunner.com/auto-air-quicksilver-chrome-4104/
Here is my IRIS with Quicksilver nose.

 

[Adrian A]

I use Createx Quicksilver over their Gloss black. This produces a very nice chrome or polished aluminum that is durable.
https://spraygunner.com/auto-air-quicksilver-chrome-4104/
Here is my IRIS with Quicksilver nose.

That looks great! I don't have a sprayer, though.

 

[Adrian A]

Second coat of epoxy, this time with low density (microballoon) filler and colloidal silica, curing in the hot sun. Surface got up to 160F



Sanded down

Onto the sandable primer. The scratches in the plastic are nasty. It may also have been too hot out to do this spraying.

 

[Adrian A]

The primer wet-sanded down nicely, so it looks like I just need one more coat of primer, then wet-sanding to be ready for the top coat. However, it occurred to me that I forgot to apply a bunch of grease to the coupler to keep it from getting bonded into place when I did my last epoxy filler. I dug around to find the seam in one spot, and it's not responding to a twisting screwdriver, so I think I'm in trouble. I figure the best course of action from here is to just bite the bullet and use the same chop saw I used to cut the tubes originally, to re-cut them down the seam, sacrificing the coupler but hopefully hitting the edge of the airframe tubes on both sides. Then I will have access to peel the coupler off of the inside of the airframe tubes wherever it might be stuck.

In better news, the new circuit board for the pancake av-bay is working.

 

[Adrian A]

Decided to go for the silver today:



Quite a few flaws if you look closely, but I'm happy with the overall effect. I'm going to let it dry quite a while and then do a laquer clearcoat. Between the filler, the primer, and the paint, I think the finishing might weigh more than the structure. Looking forward to flying this on a small-ish long-burn 38.

 

[waltr]

That silver looks good. Not seeing flaws in the photo.

 

[Adrian A]

This morning I shot it with a clear lacquer to preserve the chrome effect, and the opposite happened. It instantly de-aligned the metallic particles and now it's just a run-of-the-mill silver. Pretty disappointing. I think I'll try flying it like this next weekend and then if I'm in the mood, I may try wet-sanding the paint off and try again with the chrome. Maybe it was an incompatibility between the paint and the lacquer?

 

[Handeman]

This morning I shot it with a clear lacquer to preserve the chrome effect, and the opposite happened. It instantly de-aligned the metallic particles and now it's just a run-of-the-mill silver. Pretty disappointing. I think I'll try flying it like this next weekend and then if I'm in the mood, I may try wet-sanding the paint off and try again with the chrome. Maybe it was an incompatibility between the paint and the lacquer?

Reread the directions on the chrome paint. Sometimes you need to "recoat" within a few hours or wait a week or more. That's gotten me a time or two when I figured 5 days was long enough, but it wasn't.

 

[Handeman]

Maybe it was an incompatibility between the paint and the lacquer?

Back in the '70s when painting cars the rule was, "Enamel over lacquer is OK, but never put lacquer over enamel". Not sure if that applies to today's paints, but probably not a bad rule to follow.

 

[David_Stack]

Many of the 'chrome' effect paints will experience this (the dulling of finish) when clear coat if applied over top. Alclad offers a faux chrome paint that needs to be applied with an airbrush, and then a companion clear coat which allegedly will not dull the chrome finish, not sure if their clear would be compatible with what you sprayed.



You might also want to try Future or whatever name it goes by currently...

 

[Pem Tech]

The new Blue Raven altimeter that's in development can be launched with any electronics orientation, so for larger diameter rockets, it opens the possibility of mounting them flat to reduce the av-bay length. I'm working on a new av-bay mounting accessory, similar to the Featherweight Power Perch, but designed around flat-mounting redundant Blue Ravens in a 0.5" long av-bay cavity.

But I don't have a 4" rocket to test this out in, since I'm more of a MD guy, so I decided to try building something new for me. Basically I want to fly a very short av-bay (~ 1" long with hardware and bulkheads) in a fun way, so I decided to make a dual-deploy HPR rocket that's almost all nosecone and boat tail.

Apogee has some nice long, slender 4" nosecones, so I'm designing around 2 of them:

View attachment 528309

Oh man, that is so cool! Following.

 

[Pem Tech]

Many of the 'chrome' effect paints will experience this (the dulling of finish) when clear coat if applied over top. Alclad offers a faux chrome paint that needs to be applied with an airbrush, and then a companion clear coat which allegedly will not dull the chrome finish, not sure if their clear would be compatible with what you sprayed.



You might also want to try Future or whatever name it goes by currently...

Haven't tried Future yet. Have had a bottle out in the shop for years but haven't used it yet. Love the look of chrome but gave up and went to Krylon for plastics Nickel Shimmer. It isn't quite as attractive but it looks old timey sci-fi and is as hard as moms cornbread.

Does the Alcad stay soft to the touch or harden up with time. My original Space Ark from the early 2000's wears chrome paint and it is still soft!

 

[Adrian A]

Glad I'm not alone in this

Many of the 'chrome' effect paints will experience this (the dulling of finish) when clear coat if applied over top. Alclad offers a faux chrome paint that needs to be applied with an airbrush, and then a companion clear coat which allegedly will not dull the chrome finish, not sure if their clear would be compatible with what you sprayed.



You might also want to try Future or whatever name it goes by currently...

Glad I'm not alone in this. Very relevant video.

 

[Pem Tech]

This morning I shot it with a clear lacquer to preserve the chrome effect, and the opposite happened. It instantly de-aligned the metallic particles and now it's just a run-of-the-mill silver. Pretty disappointing. I think I'll try flying it like this next weekend and then if I'm in the mood, I may try wet-sanding the paint off and try again with the chrome. Maybe it was an incompatibility between the paint and the lacquer?

Never had any luck spraying clear coat over chrome, it always dulls the finish, no latter what brand of paint. (Dutch Boy, Krylon, Rust-Oleum, generic etc...)

 

[Adrian A]

I have been thinking about how to install the tracker. My plan has been to put it flat on the bulkhead that closes off the conical part of the nosecone. But then I decided I didn't want it just hanging out in the breeze and the dirt, so I made a little house for it using the center circle from the av-bay laser-cut 1/4" plywood ring as the roof. Next I needed a cylinder or some walls. I have a 3" FG coupler that I could cut a ring off of, but it is a little small to lay the tracker out flat with a 90 degree antenna. then I spied a roll of blue tape that I had just finished, and the center cardboard core is the perfect size:




Not shown are the two eyebolts that meet in the hex coupler that I ground down to the right length so that when it's all clamped together I can tighten the eye bolts securely against each other with wrenches. The 90 degree antenna should arrive early next week, and I'll complete the installation then.

Next up is the tip of the nosecone. In order to make the rocket stable with the largest J 38mm motors hanging out the back, I needed to add about 100 grams to the tip, along with a shock cord attachment.

I put a nut on another eye bolt at and dropped it in so that the nut and the eye are both close to the wall of the cone. Then I weighed out 100 grams of shot (the weight of the bolt is some extra margin), and experimented to see how much would fit into the tip ahead of the eye bolt nut:


You can also see the eye bolt at the top, with some kevlar thread I'll use later to fish the full shock cord through. I didn't want to get epoxy on the shock cord I want to use in flight.

Next, I drilled some anchor holes in the tip for the epoxy to run into from the inside, to improve my odds that the cast tip will stay anchored despite the slippery plastic, and then I covered the holes with blue tape from the outside.


Then I mixed up some epoxy, poured it in, poured in the forward shot, hung the bolt down on the thread, poured in the rest of the shot, and adjusted the amount of epoxy left to cover all the balls:


This is what I wanted. The eye bolt is half-submerged in an epoxy/lead shot mixture and it's curing now.

 

[Adrian A]

The paint is already pretty trashed on this rocket, so I've been thinking about how to refinish it. I really liked the idea of a chrome mirror finish, but want something with a chance to be durable, so I'm going to experiment with silver (actually aluminum) leaf. It's pretty inexpensive, under $10 for the leaf and about 12 for the leaf adhesive kit with a brush. None of the paints I've tried have interfered with the GPS reception, but this might. We'll see.

 

[Adrian A]

My silver leaf arrived today. The adhesive will arrive tomorrow, but I thought I'd just put a piece on without adhesive to see how it will go.

This is just adhered with static, and I smoothed it out -ish with my fingers.
It looks like I'm going to wind up with some texture in the end, but I'm o.k. with that because the luster is 100% so it will look cool from a distance. I think this will be fun.

 

[waltr]

That is shiny.