Cluster is Back! A progressive build thread

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JDcluster

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Location
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Preface:
Back years ago (circa 1997 to 2001) I loved clusters.
HP 2 stage, 3 motors, air-starts and all!

My next 2 projects brings me back to what I was doing in the 90's where; SU motors were common.
This first rocket has been put on the back burner for almost as long.
I've had the RockSim file forever!
The motor mount has been built for quite some time.

2014-10-17 21.31.39.jpg

I got away from it to concentrate on EX, some call it Research; where you build you own stuff.
I learn quite a bit from doing so.

This time around: the electronics are much better, with better tracking equipment.

This build thread will focus on the first of 3 planned builds for 2015 flying season.
Those who know me on FB, have seen a sneak peak of this already!

Rocket specs are as follows:

Rocket Diameter: 6.1"
Airframe Material: PML / Red Arrow Hobbies Phenolic tubing
It will be glassed with 6 oz and possibly a layer of 3 oz E glass for a better finish.

Rocket length: around 8 to 9 ft tall

Motor configuration:

1 central 54 mm

6 x 38 mm outboards

Almost forgot about the fins; there will be 6 fins!

Target launch: LDRS 34, Potter, NY


I will continue as long as people are interested in it.

JD
 

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My typing is slower than my rocket building as; I'm neither a writer or a poet ;)
Like all good Cooking and Woodworking TV shows; I'm a little further ahead then this post.
It will give everyone time to digest each update.

The first line of business is to trim the central 54mm to length.
2014-10-17 21.35.16.jpg

Hers's another view of the motor mount

The RockSim file is rough and hasn't been touched in a while.
Some things may change through out the build.

The fins have been cut out of 1/4 x 5 ply birch plywood.
Fins have the same dimensions as the RKT file
They were cut and beveled by Smokin' Rockets back When Bill Rossi still owned them.


JD
 

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I forgot to mention that:
Adhesives used for this project will be:

Wood Glue ( Tite bond) CR to motor tubes
backed up with:
Bob Smith 30 min epoxy, used for most of the build.

Fillets and laminations:
West Systems epoxy
Aero Poxy laminating epoxy


JD
 
Next, the obligatory dry fit process:

2014-10-13 20.38.04.jpg
2014-10-13 20.37.55.jpg

The fins before I attach them.
2014-10-20 22.39.15.jpg

I use to slot the tubes all the way to the end.
The problem with that is: that the tube either stretches or shrinks
depending on the winding process.
You also lose rigidity on the tail end.
I'll be trying a new technique along with one of my old ones, to help improve this.

Stay tuned.....
 
Can't wait! Interesting using the Titebond for the CR/motor tube joints. I'm sure it will work great. What specifically are you using for tracking? Also, what are you doing for your fin joints? Any tip to tip or root/MMT glassing?
 
Tracking will be a CSI RF tracker.
The fin joins will be 6 oz glass strips and tip to tip.

I did hit one snag when dry fitting: no room to run conduits for the air-starts. :(
If you look at the middle picture the conduits are installed...
They were pulled out to allow the fins to butt up against the 54 mm tube for bonding.
That is why dry fitting is a necessary step!

I will try to run them on the outside of the tube most likely next to the fins tube joints...
I have the FG and Aero Poxy but, I prefer West and need to get my order in before it gets too cold.

JD


Can't wait! Interesting using the Titebond for the CR/motor tube joints. I'm sure it will work great. What specifically are you using for tracking? Also, what are you doing for your fin joints? Any tip to tip or root/MMT glassing?
 
Am I boring anyone yet?

Just ordered the West Systems epoxy group size B or gallon kit with 206 hardener along with correct size pumps.

Here's the next progression pics:
With the motor mount glue into the tube using Bob Smith 30 Min epoxy
I proceed onto gluing in the first of the 6 fins.
2014-10-19 21.55.27.jpg

I waited about an hour or so between each fin.
It took some trial and error on how much Epoxy to mix.
I started out at 3.5 grams each of hardener and resin.
4.5 grams seems to be about the right amount per fin.

The first one is the hardest because; I don't have a fin guide or jig that can handle 6 fins this big.
2014-10-20 16.30.21.jpg

The second fin is 180 degree from the first.
2014-10-20 17.02.44.jpg

JD
 
Mannnn,,,
I can't wait to see this beast fly....
Jeff,,
Either this is the coolest thing I've seen,,
Or,, this is the coolest thing I've seen....lol

What's projected weight .......................

The BEAST.........................

Teddy
 
Very cool build- Subscribed!
I love a good plywood and paper build. Fiberglass is awesome, but I have to say, from a building perspective, I prefer to work with paper and wood. 6 I1299s for the first flight, right?:D
 
Ted, right now; not really sure.....
It all depends on how much over building I do.

Another fin, another pic:
2014-10-20 21.51.43.jpg

This is where I'm at right now:

2014-10-21 18.16.33.jpg


JD

Mannnn,,,
I can't wait to see this beast fly....
Jeff,,
Either this is the coolest thing I've seen,,
Or,, this is the coolest thing I've seen....lol

What's projected weight .......................

The BEAST.........................

Teddy
 
Jeff,,
What do you do,,
run brass tubing down, between each pair of 38 mm tubes for shooters wire...
Then you can mount whatever electronics that's going to do the airstarting up top,,,
either in the booster or in the coupler / Av bay ???

Teddy
 
Can't believe I missed this thread!!!! I can't wait to see this thing fly:):) looks great so far.
 
Lookin' good!
I'd run some glass or carbon tubing (kite store) next to the fin just inside the airframe tubing, between each pair of 38's. Depending on the size of tubing, you might get by with only 1 conduit (and careful routing/taping of igniter wires around the base!).
-Ken
 
I use AL tubing it's less expensive and also lighter.
I had to pull them out for the fins to fit.
IMG_20141022_155356336.jpg
My order from IMG_20141022_155356336.jpgJamestown Distributors came in.

JD
IMG_20141022_155356336.jpg

Jeff,,
What do you do,,
run brass tubing down, between each pair of 38 mm tubes for shooters wire...
Then you can mount whatever electronics that's going to do the airstarting up top,,,
either in the booster or in the coupler / Av bay ???

Teddy
 
I use AL tubing it's less expensive and also lighter.
I had to pull them out for the fins to fit.
View attachment 188200
My order from Jamestown Distributors came in.



JD


Jeff,,
What do you do,,
run brass tubing down, between each pair of 38 mm tubes for shooters wire...
Then you can mount whatever electronics that's going to do the airstarting up top,,,
either in the booster or in the coupler / Av bay ???

Teddy
 

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A little hick-up, from trying to post from my phone over Wi-Fi.
That is why you see 3 of the same picture in one post.


JD
 
Some more pics with my new technique that I'm trying for the first time:
2014-10-22 18.21.21.jpg
2014-10-22 18.21.13.jpg
2014-10-22 18.21.30.jpg


When the fins were cut, the tang or tabs leading to the motor tube were hair on the long side.
To fill in the gap I cut tongue depressors long enough to fit.
I used what was left over on the aft end, so they stick out some before trimming..

JD
 
How come you didn't just sand the fin tabs down ???
Looks like in the end it would have been easier.........

Teddy
 
You lose the squared edge, leading to unevenness.
It's allot easier cutting wood that's 3/32" of an inch thick vs the 1/4" plywood.

Next up:
Mounting the AL conduit tubes to the outside of the rocket.
Not sure if I'll use 3 or 6 of them.....


JD

How come you didn't just sand the fin tabs down ???
Looks like in the end it would have been easier.........

Teddy
 
I hope you don't mean to run the conduits on the outside of the airframe! How about this:
Untitled.jpg

Just use a long drill bit to go through your centering rings, then epoxy your conduit in.
What are you doing for motor retention? I've used 3 threaded rods to hold 7 motor clusters... Just place them between the central and each pair of outers:
20130430_202423_zpsded00865.jpg

-Ken
 
I was thinking of using the same holes that originally drilled for the conduit. Threaded inserts in their place.

JD
 
Just a small update; I didn't get much done over the weekend (out of town).

I just weighed the booster.
So far:it weighs a little over 5 lbs.
That's lighter than I expected but, still a long way to go.....


JD
 
Awesome, buddy! And external conduits work...my Ultimate has the two PET2 channel wires (cat5 cable) running right down the airframe and sealed against the tube with a few long strips of packing tape. Works great...and one wire set is orange/white, the other blue/white to match the paint:wink: It's not the most ideal, but it works!

Regarding your glassing and tip-to-tip job, I'm assuming you're doing that externally from fin tip, across the airframe to the other fin tip? I'm considering internal tip-to-tip for my next project. I like building up the motor mount first. Attach CRs, fins, then glass tip-to-tip, install outboard motor tubes and slide into pre-glassed and slotted airframe. Yes, that can leave a little bit of exposed slots at the base of the bird but that doesn't bother me. I've only glassed fin roots and airframes at this point...I don't think I've done a full tip-to-tip job thinking back (this includes a 5 year or so gap).

Can't wait to see this beast rock!!!
 
A small update as I haven't had allot of time to work on this project....
I sanded down the the glue joints along the fin roots and applied first set of six fillets.
I still haven't decided on how I will mount to the conduits to the rocket.

2014-11-01 19.35.55.jpg
2014-11-01 19.36.10.jpg

JD
 
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