My first 2 stage

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Pictures always work better:
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For the gray piece I just take a shortie piece of BT, cut out a small strip, and then just compress it into place. Doesn't matter if it fits perfectly or if there's a gap.


For your fin, *I* would cut a single piece, grain parallel to leading edge, and paper it.

Thanks. That confirms my thoughts.

Out of interest, is the small end just glued with a little smear of wood glue?
 
Out of interest, is the small end just glued with a little smear of wood glue?

Recently I tried putting a smear of Titebond II around the BT, and sliding the transition over it. Big mistake: the TBII seized the shroud before it was in position, and I needed to tear it off completely before it hardened. So I would use a non-seizing glue for it, like white glue.

Or, skip the ring of glue entirely. Slide the shroud into place and glue at the large end, and then (eventually) just fillet around the outside of the small end with your favorite fillet glue. That's not really a structural joint anyway, so it just needs something to seal it off and make it stay put. Filler around both ends completes the job to smooth everything off.

My most recent (mis)adventures in this area are shown here and here.

Again, there are many many different variations on how to do this. I'm evolving a process that works well for me.
 
Thinking about grain direction on the fins.

Because of the square end on booster fins, I can't just cut the whole fin out of a single piece of balsa. (The hashed part of the pic is the bit I'm worried about - the fwd corner is BOUND to get knocked off)

I'm thinking of two options:

Option 1: I make the whole fin less the hashed section in the pic out of a single piece using the sustainer fin LE for the grain direction, then adding a tip cap with the grain parallel to the rocket on the end. This means cutting and gluing pieces which is prone to cutting inaccuracies.

Option 2: I use a horizontal grain for the booster fin as pictured

Thoughts?

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For the fins, why not eliminate the "tab" altogether? Perhaps continue the line between the fins all the way to the edge so that both are trapezoidal. Imagine cutting between the fins and just keep going. The top fin would have a point at the end so you would have to harden it to protect it from hard landings.

As far as grain direction, I would keep the booster fin's grain aligned with it's leading edge. Boosters tend to be hard on the fins as they don't parachute down but tumble. At least that's what I see in kits all the time anyway.
 
Snrkl, you may not like this layout, but what you have to remember is, what you dish out in a design, has to be properly assembled. Sometimes a short cut will work out, but all too often, it doesn't. Your sustainer fin might do alright with just a paper job, but I have to question the fragility of that booster fin. In the eye of someone like myself having done a plethora of 2 & 3 part fin assemblies, I will suggest that you consider making that booster a 2 piece assembly. You'll have to pre-fit & sand to fit all of the pieces tightly and mark them accordingly like set #1, set #2 #3 yadda yadda. Just a little Titebond at the glue joints on wax paper and a very flat surface, assemble all of them and place another wax paper on top. Have a second flat board/surface to lay on top and weigh it down. Let it sit overnight just to be on the safe side. The pic is not to scale, but a reference for you to use. If I were building this rocket, it's what I would do.

(additionally) either the leading or trailing edge of the sustainer's second piece will work for grain direction.

snrkle fins.jpg
 
I'm also guessing the ejection charge / motor ignition is sufficient to kill the tape?



Yes, if you don't overdo it. I learned the hard way when my taser twin dropped the booster but the motor didn't separate and resulted in a horizontal disappearing killer dart.
 
Parts ordered and en route.

I'll be starting construction next week.

Won't be ready in time for the next club launch on the 9th I don't think..

We'll have to wait and see when the CRs arrive.

I also realised I have two Pre marked transitions on card from the Estes designer special I have.

I might give those a go first.
 
OK - just doing the last eyeball on my design before I start cutting things... (still waiting on the couplers and CRs)

I am just thinking: I am using a tube coupler sandwiched between two CRs at the top end of the upper transition. The plan is that the transition will join the 24mm BT55 to the 41mm BT60, above the transition will be a tube coupler sandwiched between with the two CRs.

Now I am trying to figure out how much coupler I need.

The design as is has 20mm of coupler (shown in green)

OpenRocket020.jpg

I'm thinking that I actually need one caliber of overlap - making the coupler at least 40mm..

What is the general thinking here?
 
[Edited] Never mind - I realised I was the one having the moment. I will learn how to read a graph one day.. I was looking at the wrong plot (and the wrong scale) - Streamer recovery actually has the booster returning at 15m/s (50km/h) which is a little closer to what I was expecting..

[Original post]
I had a moment to pause this morning when looking at the booster stage a little more closely..

I hate walking, so I have been looking at adding a streamer to the booster using a small pod on the rear of the sustainer that pulls a rolled streamer out on ejection...

When profiling the different designs (with and without streamer) something odd popped up: with the streamer, OpenRocket shows my ~25g booster (=booster + spent motor) returning to earth from 100m at 180km/h versus the tumble recovery at 5km/h...

180km/h seems very fast for something that light coming back from 100m... Is there something that I am missing here or is OR just having a moment perhaps?


Streamer Recovery:
OpenRocket024.jpg

Tumble Recovery:
OpenRocket023.jpg
 
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Decided to up the transition couplers to 40mm length overall. I ended up increasing the upper BT60 section by 20mm to compensate.

I've also decided to use CRs top and tail of each of the transition (it's a coupler sandwich!)

I've shifted focus tonight into trying my hand at hand made paper transitions.

Long story short: best results achieved by printing the OR transition templates directly onto 210GSM card stock and using a circle cutter.

Damn - once I figured the workflow out it was super easy and the fit is scrumptious.

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I used the "cut off the tab completely and paste it under both halves" method using a very small amount of PVA wood glue.

Can't remember who suggested it but drying the transition on a curved surface worked a treat:
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All up - very happy so far.

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Question: do others CA soak before or after installation?
 
Looks good. On cones & transitions I soak with CA after it's in place.
 
Here we are lucky to see something really special: two wild transitions in their natural habitat. We're hoping they will find each other as suitable for coupling. If they do, we can expect them to join together in a mating ritual that is as complex as it is unique - all taking place on a suitable rocket that they will form together with their bond any day now....

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(Sorry. I couldn't resist! 😜)
 
Here we are lucky to see something really special: two wild transitions in their natural habitat. We're hoping they will find each other as suitable for coupling. If they do, we can expect them to join together in a mating ritual that is as complex as it is unique - all taking place on a suitable rocket that they will form together with their bond any day now....

(Sorry. I couldn't resist! ��)
Neither could I. Your quote made me dig up this poem I wrote a few years back....

You like it on top. That’s easy to tell.
You take the lead, when we’re running the rail.
You sport the lifeline, for the protector inside,
Which is also protected, from the burn down inside.

Your sleek solid curve, is majestic indeed,
And I love it when you aft, is inside of me.
I love you, my topper, you make me complete,
Together we’re awesome, beautiful and sweet.

You take me to heights, that few can imagine,
I am the crew, but you are the captain.
You are the probe, and I am the socket,
Together we make, a superior rocket.
 
Neither could I. Your quote made me dig up this poem I wrote a few years back....

You like it on top. That’s easy to tell.
You take the lead, when we’re running the rail.
You sport the lifeline, for the protector inside,
Which is also protected, from the burn down inside.

Your sleek solid curve, is majestic indeed,
And I love it when you aft, is inside of me.
I love you, my topper, you make me complete,
Together we’re awesome, beautiful and sweet.

You take me to heights, that few can imagine,
I am the crew, but you are the captain.
You are the probe, and I am the socket,
Together we make, a superior rocket.

Ok - at least I know I'm not the only massive nerd online tonight... ;^)
 
Here we are lucky to see something really special: two wild transitions in their natural habitat. We're hoping they will find each other as suitable for coupling. If they do, we can expect them to join together in a mating ritual that is as complex as it is unique - all taking place on a suitable rocket that they will form together with their bond any day now....

View attachment 323371


(Sorry. I couldn't resist! ��)

I think you have been out in the sun too long and you're in the middle of winter!
 
Construction started tonight.


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Starting with the transition couplers for the sustainer.

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I'm hoping to be able to do a dry fit tomorrow.

I'm already thinking 170mm for the payload tube (less the 40mm transition couplers and the NC shoulder) isn't big enough.

Tempted to use the other side of the BT60 for the payload section, essentially increasing the segment from 170mm to 207mm... I'll see how much room there is when I dryfit all the BT tomorrow night.

At least with this design, I can put dogbarf in the (very) long MMT and use a sheet of wadding paper wrapped on the bottom half of the parachute.

I just want to make sure I can get a JLCR and an Altimeter3 in there!
 
MMT finished - about to glue on the fin can, the payload bay and affix the transitions into place.

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I've been pottering along - haven't been taking pics as I've had my parents visiting for a few weeks which has limited my play time.

Current status: body tubes and papered / CAd glued and filleted fins on the sustainer are done. The label paper for the fins was super easy.

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I've wood filled the transition edges and sanded once - currently waiting for the next layer to dry so I can do final sanding.

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Second stage coupling is a little stiff for my liking - I'm slowly sanding/shrinking the booster coupler to make it a little less sticky.

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The booster fins are a little harder to paper as I can't wrap the label paper around the leading edge. I botched one and was fortunately able to remove the label before it stuck too well. I've rounded Leading and Trailing edges on the booster fins and will try label papering them tomorrow.

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I've also decided to add a streamer to the booster (it was fluttering 50+ meters away in the sims) to bring it down a little quicker. Adding a streamer means adding a streamer pod to the sustainer which I'm planning to do with some 13mm BT.

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I've managed to put a small window in the outside of the booster BT and fed some Kevlar through, so the booster shock cord will run outside the booster to the rolled streamer in the sustainer pod.

I've also mastered cutting ripstop nylon with a soldering iron - damn that's easy!!

I've also had the frisket film for the flame pattern delivered, and I've discovered laser printable decal film, which is *AWESOME*...
 
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This is how I make my own chutes. I have poster board templates I lay on top of the ripstop and sear around the edge of the template. For some reason, a soldering iron wasn't getting hot enough, so I use a wood burning tool with the angled knife-like tip the zip around the edges. This is such a great method because it eliminates the hem from sewing the edges of the chute. Then I use some 35# woven fishing line and with a large needle, I sew the shroud lines in place.
 
Ok - have been busy so I haven't been photographing as I went, but it was mostly boring bits anyway.

Principle construction is now complete.

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I dry fit tested with a pair of d12 motors today and it all fits nicely with tape retention and staging connections.

I'm worried the rolled streamer might fall out of the streamer pod under g-force by itself, so I might need to look at a mod later to cover the rear of the streamer pod - I'm thinking something like a cork on the shock cord that plugs into the rear of the pod but will pop off with the separation of the first stage... I'm thinking a foam core board plug made of several layers and sanded to fit might just do the trick.

I'm still waiting for my JLCR to be shipped - it's on backorder at ausrocketry at the moment. Patience is a virtue I guess.

Given this is designed to fly to 400m (1300ft) I'm not planning on walking 250m+ to collect it with only moderate winds (this thing has 5cal of stability with motors and 9cal empty, so weathercocking is a thing...) I won't be flying it without a chute release!

Tomorrow I start the paint job.

A few new challenges and methods planned:

1) I'm trying a local automotive filler/primer as an alternative to CWF for filling tube spirals.

2) I'm planning on using frisket film for the first time for the flame pattern on the payload section.

3) I'm going to have to make damn certain none of the interstage couplers get paint anywhere near them (inside OR out) as that will make it a very bad day on this build.

All up, I'm pretty happy and excited about this build!
 
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Nice work! I don't see any launch lugs. What will you use?

Funny you should mention that - I realised JUST before I set out to paint it yesterday that I'd forgotten.

I've added 2x 5mm wax/paper drinking straws to the payload and fin can as launch lugs.

I misaligned the top one first try and had to yank it before it dried, so that meant waiting 12hrs for the glue to dry so I could sand it and redo...

While I was waiting I also filled a few seams in the plastic NC.

I tried a new method - I've not liked the results using ca to fill the seams and sanding, so I filled the seams with super wet CWF and sanded back once dry. Once it was smooth I then soaked the CWF with thin CA and sanded again. Long story short: smooth as a baby's backside and will be my go-to method for plastic NC filling in the future I think.
 
Ah, the order of assembly! It shall not be ignored! You had primer fever and wanted to see it all in one color. Happens to me too! Good catch! Keep us posted :)
 
Bird is primed. I think it needs one more coat then sanding. I haven't used this filler/primer spray before.

One minor set back - the frisket film I ordered for the flames, doesn't work with acetone based rattlecan paints.

So now I'm not sure how I'll do the flames - I'm thinking about experimenting with a printable decal maybe?
 
Bird is primed. I think it needs one more coat then sanding. I haven't used this filler/primer spray before.

One minor set back - the frisket film I ordered for the flames, doesn't work with acetone based rattlecan paints.

So now I'm not sure how I'll do the flames - I'm thinking about experimenting with a printable decal maybe?

You can lay down a layer of painter's tape just like you were going to with the frisket. Another way is to use very narrow, flexible tape - there's tape designed for laying out this kind of design.
 
Build update:

Frisket film arrived today, so of course I finished painting the sustainer:

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I decided that the dark blue I used on the booster was too dark, so I've swapped to brighter blue for the sustainer.

Now the booster needs its fins repainted.

Interesting discovery - I left the painted booster on a shelf in the garage that gets afternoon sun. The paper sticky labels used to paper the fins have delaminated and the fin was suddenly very fat.

Colour me learned about not leaving fins in the sun...

Currently trying to re-press the offending fin with some heavy books before I repaint the booster fins.
 
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