Excel 5.5” Upscale

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neond7

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I am a huge fan of the Binder Design kits - in fact, the Excel was the first dual deploy kit I built, and I still fly it to this day.

As I got more involved in the rocket hobby, I found myself favoring 5.5” kits. With that in mind, I have set about building an Excel 5.5” upscale!

I’ve ordered a fair amount of kits and hardware from Mike Fischer over the years, and he was cool enough to cut me some upscale fins and vinyl for this project. And of course I’ll be ordering the avionics wiring and anodized charge wells from Doghouse Rockety.

The body tubes, nose cone, and centering rings are from Always Ready Rocketry.

Enjoy the build!
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The 4” Excel kit looks small next to its big brother! Love flying it on a J350W.
 

neond7

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One of the first things I did was to fiberglass the avionics bay bulkheads and the upper and lower centering rings. Makes it easy to clean them later after the ejection charges get them dirty.

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I used leftover scraps of fiberglass, one layer of 6oz and 1 layer of 3oz.
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Once the parts were wetted out with epoxy,
I added a ceramic tile and some heavy weights to keep squeeze out the extra epoxy and keep it light.
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Once it had partially cured, I removed the weights and was about to remove the peel ply.

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Here I had trimmed the fiberglass overhang.

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Once the overhang was trimmed, I used a finishing sander to clean up the outside edges and dremmel to clean up the inside edges. I’m very satisfied with the results.
 

neond7

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***Please note*** If you happen to see additional parts being worked on, I’m also building a Horizon clone to replace the one I built years ago for my L3 cert.
 
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neond7

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Next up is the avionics bay. The blue tube bays use a cut down piece of body tube epoxied into each end of the bay to keep the bulkheads in place.

First I measured and marked where the band will be epoxied into place.

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Once I had measured where the band will need to go, I mixed up 8 grams of Aeropoxy and so spread it across the area and smooshed the band into it, forming a nice bond and a natural fillet.
 

3stoogesrocketry

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Fantastic build and a great rocket . The Excel Plus on a AT H123 WL was my first high power rocket in 1996/7 time frame. After that it was a trustworthy park flyer on a AT G125 BT till a Rocket Flight H220 Silver Streak blew the nozzle about 100 feet up. It turned over and just about took out the LCO table .
 

neond7

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Got a little bit more completed this evening.

First up, I drilled some holes in one of the centering rings and installed (with a few quick hammer taps) the stainless 10-24 t nuts. Thwill hold that SCP thrust ring in place.
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Next up, I used some Aeropoxy to secure the t nuts. They will see a lot of vibration and hard landings, so I don’t want them popping off in case I remove the thrust ring for cleaning. No way to get them back on when everything is assembled.
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Hopefully everyone is using good epoxy for larger rockets. I do plan on eventually stuffing an M motor in this after an initial K flight followed by an L flight.

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To make using Aeropoxy easier, these squeeze bottles make measuring out grams of epoxy really pain free.
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Finally, I installed the last two bulkhead retention rings in the avionics bays. Aeropoxy cures really slow, but it will be good by morning.

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neond7

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Last week I glassed the fin tube. One layer 5.5 oz s-glass and one layer 3 oz fiberglass.
I’ve done lots of fiberglassing over the years and this was one of my worst jobs. Lots of wrinkles.
My epoxy is getting pretty old, the hardener has turned a purplish color. All in all, not happy and it will take a lot of finishing work.
The weight penalty wasn’t bad, the tube was 2 lbs, 7.2 oz before and 3 lbs, 7.2 oz after glassing.

Measuring out the glass.
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Cutting to fit:
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I use a plate to pour the mixed epoxy on to keep it cooler for a longer

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Soooo many wrinkles!!!
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neond7

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This evening I fiberglassed the upper tube. Less than a pound added - 1 lb 9.4 oz when I started with final weight 2 lbs, 5 oz.
Once again, more wrinkles. I’ll need to get some fresh epoxy, this old West Systems is curing very fast and thicker than it should be and harder to work with.

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neond7

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I’m also starting on the motor tube and centering rings.
I added the upper u-bolt, making sure to epoxy the threads to keep them from ever backing out.

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Tomorrow I’ll epoxy the top and middle centering rings onto the motor tube.
 

neond7

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I mixed up some West Systems fairing compound and applied it to the wrinkles on the lower tube. Tomorrow I’ll put a 150 grit sanding pad on my finishing sander and smooth it all out. The fairing compound sands really easy, so it looks worse than it is. Not saying I’m not in for a lot work to get all these wrinkles fixed…
 

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crossfire

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Did ARR slot the tube for you?
 

UPscaler

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This is super rad. I have an Excel that is older than I am and I love the thing. I don't fly it as much as I should because I'm scared to road trip with it, so it's a local launch queen.


Braden
 

neond7

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Did ARR slot the tube for you?
Yes they did. Took a little tweaking with a dremel, but now the fins slide in, still a tight fit so they won’t be slopping around when I epoxy them in.
 

neond7

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The epoxy fairing filler cured overnight. I hit a spot of it with the finishing sander, 150 grit pad to see how well it filled the wrinkles.
The sander chewed through the filler with ease, the darker spots are the low spots that will need additional filler. That was only about 2 minutes work, so I think these wrinkles will be fairly easy to resolve. A little Bondo at the end and it should all end up looking good at about 6 ft away.

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neond7

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Using the finishing sander I sanded down all the fairing filler. Starting to look much better now, those wrinkles should be smooth by the time I’m done.
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I mixed up another batch of fairing filler (thicker this time) and applied the second and hopefully the final coat. I also applied the first coat to the upper body tube, but it isn’t as bad.

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neond7

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Next up, I mixed up some Aeropoxy structural epoxy and attached the upper centering ring. Later I’ll sandwich the fin roots between the middle and rear rings so I can get the correct distance between the rings and epoxy on the middle ring.
Once that is done, I can epoxy in the motor mount (after adding the rail button backings) and leave the rear centering ring free. I can then tack the three fins in and pullout the rear ring to add extra reinforcement to the fin roots. Maybe a shot of foam. Then I’ll epoxy in the rear ring.

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neond7

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Today was round 2 of the fairing filler sanding. Messy work, but it is really helping get those wrinkles hidden.

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Once the sanding was done, I found some additional areas that needed some touch up so I mixed up some more fairing filler and applied it to the low spots. Round three of sanding coming up soon!
 

neond7

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I epoxied on the middle centering ring. The fins will be a snug fit when I tack them in. I’ll leave the rear centering ring loose for now so I can reinforce the fin root connection and add the rear rail button backing.

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neond7

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Rail button time! I believe all rail buttons should be firmly attached. I’ve never had an issue with a rail button attached this way.
First I cut some little wood blocks to use as backings. Then I drilled the correct sized hole and added the brass inserts. The blocks were taller than I wanted so I then cut the height in half. I’ll carefully add a few tiny dabs of epoxy to keep the insert in the block as it will see a lot of vibration over the years.

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neond7

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I couldn’t resist doing some dry fit of the parts, in addition to ensuring the rail button backings had proper clearance. The fins were all nice and tight in the slots. It took some work with a finishing sander to slightly reduce the OD of the centering rings, they now slide in firmly but smooth.
It had gotten late so I didn’t epoxy the motor mount into the tube, that will be the next step so I can start tacking fins.

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ECayemberg

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Cool! Looking good!!!

Seeing the fins on reminds me of one of the Rocket R&D Big Brutus; one of the first "big" rockets I saw back in the day! Which makes sense...as the Excel is a derivative of the Brutus.

Cheers!
 

Bat-mite

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Cool! Looking good!!!

Seeing the fins on reminds me of one of the Rocket R&D Big Brutus; one of the first "big" rockets I saw back in the day! Which makes sense...as the Excel is a derivative of the Brutus.

Cheers!
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