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qquake2k

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I know I saw this name here, but can't remember who it was. If it was you, or someone you know, I'd like to give credit where credit is due.

I've wanted to do a design like this for a while now with two body tube sizes and no transition. Originally I was working on a 4"-3" design, but downsized it to 3"-2.2". I wanted to be able to fly it on mid power G's at SARG, and small H's at Snow Ranch. I think I've succeeded. Open Rocket doesn't like the design, and keeps telling me there is discontinuity in body tube sizes. I had to do some trickery to get it to accept the fins on the lower section. I'm hoping that the stability and sims are relatively accurate. My gut feeling is stability won't be a problem, but the sims might be suspect.


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qquake2k

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I thought about going with three fins instead of five, just because of ease. Less cutting, less sanding, less fin slot cutting, less epoxying, and less masking. But in the end I decided on five fins just for the coolness factor. I've done up to six in the past, so this won't be all that bad.

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Salvage-1

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love the name and the design, simple and elegant.
MOAR FYRE!
 

Gary Byrum

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Kinda reminds me of my Skyjacker. 24mm cluster model with 3 motor tubes that extend around 10" from the bottom. Can't locate the nekkid pic which shows more clarity. This will have to do though. Flies really well. Can't see any reason why yours shouldn't.

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qquake2k

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Now that is a cool design! Love the open fins! Does it whistle? What motors have you flown it on?
 

Gary Byrum

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Now that is a cool design! Love the open fins! Does it whistle? What motors have you flown it on?
Doesn't whistle. I built it for D motors. That's all I've ever flown it with. Maiden flight was a bust though. NSL 2016 only 1 motor lit and it sharked. After the rebuild I launched it at Freedom Launch a few weeks ago. I reckon I was a bit cluster shy to fly it until recently.
 

K'Tesh

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I will be following this... :pop:
 

LithosphereRocketry

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I know I saw this name here, but can't remember who it was. If it was you, or someone you know, I'd like to give credit where credit is due.

I've wanted to do a design like this for a while now with two body tube sizes and no transition. Originally I was working on a 4"-3" design, but downsized it to 3"-2.2". I wanted to be able to fly it on mid power G's at SARG, and small H's at Snow Ranch. I think I've succeeded. Open Rocket doesn't like the design, and keeps telling me there is discontinuity in body tube sizes. I had to do some trickery to get it to accept the fins on the lower section. I'm hoping that the stability and sims are relatively accurate. My gut feeling is stability won't be a problem, but the sims might be suspect.
Very cool!

In OR, it seems to work better if you add a .001" long transition in between the sections. It should sim OK as-is, though- it just won't calculate airflow around the step.
 

Nytrunner

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Very cool!

In OR, it seems to work better if you add a .001" long transition in between the sections. It should sim OK as-is, though- it just won't calculate airflow around the step.
I'm actually wondering if a near-zero length transition would cause more sim disruption than the simple tube discontinuity! Thinking of how a reducing transition will sometimes kick the CP In Front of the entire rocket without fins. May be something screwy with how it handles that geometry.

I wholly approve of the name and the caveman decal complimenting it! Unless there were earlier usages I wasn't aware of, I used that term when discussing different rocket building approaches, Steve Shannon said he wanted it on a T-shirt, and then it got used again in the recent Drag-race rules thread.

Build on good sir! (and I just used your zipperless baffle method in my Argent!
 

qquake2k

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I'm actually wondering if a near-zero length transition would cause more sim disruption than the simple tube discontinuity! Thinking of how a reducing transition will sometimes kick the CP In Front of the entire rocket without fins. May be something screwy with how it handles that geometry.

I wholly approve of the name and the caveman decal complimenting it! Unless there were earlier usages I wasn't aware of, I used that term when discussing different rocket building approaches, Steve Shannon said he wanted it on a T-shirt, and then it got used again in the recent Drag-race rules thread.

Build on good sir! (and I just used your zipperless baffle method in my Argent!
Thank you! How did the baffle work in your Argent?
 

qquake2k

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Got the fins cut out. 1/4" birch plywood from Michael's.

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qquake2k

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Normally, I would use my miter saw to cut body tubes. But it's buried right now, by my son's camping gear. So I dug out my razor blade cutting jig.
It worked better than I remember.


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qquake2k

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I used the jig to cut the 2.2" tube, and the bandsaw to cut the motor tube.

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Nytrunner

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How do you achieve an even turn on the cutting jig?

Any guide, or just his 'manual dexterity' technique I hear talked about?
 

qquake2k

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I clamp a block to the jig to set the length. The bungee cords help hold the tube against the jig as you rotate it.

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qquake2k

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Got the centering rings cut out and sized on the lathe.

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qquake2k

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I cut out the center holes and sized them with the Dremel.

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qquake2k

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I decided to use 3/8" thick plywood for the baffle plate, since it will be smaller than usual. I drilled pilot holes all the way through, so I could drill the 1/4" holes part way from both sides. This makes the holes cleaner, with less chipping.

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qquake2k

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It turned out pretty good. I also started on the half moon baffles that will be epoxied into the forward end of the motor tube.

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qquake2k

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Got the rail button blocks epoxied onto the centering rings.

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qquake2k

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Got the rail button blanks on the centering rings sanded. I think I need a new belt on my sander. The disc worked much better.

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qquake2k

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Got the half moon baffles installed in the motor tube.

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qquake2k

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After I had epoxied the forward centering rings onto the motor tube, I realized that I put the wrong ring on the front. So I had to put another rail button block on the aft ring. Finally, I epoxied the motor tube into the aft body tube. Next step, fins.

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MikeyDSlagle

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I'm just now stumbling onto this thread. I like it. I've been working up something similar but using tube fins instead. I'm considering minimum diameter on the business end so it can fly on soda can 54s. Torn between traditional dual deploy or JLCR. Too many other projects in the way so far.

The caveman looks like something off of the old NES Caveman Games.
 

qquake2k

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That sounds like a fun project. Which 54mm motor(s) are you thinking? What size will the forward body tube be?
 

qquake2k

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Got the fin slots cut. I vacillated between 5 and 3 fins, but in the end went with 4. I recently made a 3 fin , a 5 fin, and two 6 fin rockets, so wanted to do something different. I had to make the fin tabs a little longer.

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MikeyDSlagle

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That sounds like a fun project. Which 54mm motor(s) are you thinking? What size will the forward body tube be?
For the tubes, I was pretty much on the same train of thought as you. 4" and 3" then went to 3" upper and 54mm lower. 18" upper, 22" lower with 16" exposed.

If I build light enough I can fly it on the I117FJ and J90W. Long burns on a heavy drag bird should be cool to watch. Rail speed as it sims now is around 47 ft/s which will be fine. I would have to angle the rail a bit to achieve a good vertical flight. Don't really trust the sims when dealing with tube fins and that wonky transition. And I always build heavy, which is something I need to work on.

Should fly on anything from a G to a J.

The LOC Viper family has motor tube clusters sticking out the back of the main body tube, just no transition.
 
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