LOC Viper 4 Build

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grouch

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Ok so here is my first build thread. I have been wanting to build a Viper for the longest time. Back in the mid 90's I made the mistake looking at a LOC brochure and knew that I would build one of these kits sooner or later. Little did I know it would be much later! After I recently built my Onyx and successfully flew it to level 1, I decided it was time to work on a Viper. Originally I was looking at a Viper 3 because I like 3 fins and I figured three motors would keep the launch cost down a little lower than four but I soon realized the Viper 4 is much more versatile as I could fly it on two or four motors. I could also fly it on two small E's and two big G's or four small E's or four big G's, you get the idea. So with that in mind I set out to build my version of the ultimate Viper 4 that could handle anything I throw at it.

What will make it the ultimate Viper 4? I don't really know but I'll figure it out as I go along. Let's start with the centering rings. The new version of the kit no longer contains centering rings. Apparently the old rings were a pain in the ass because there is so little meat on the rings after the four 24mm holes are cut. The new kits use a coupler that you glue the motor tubes into and fill the voids between the tubes with tissue and epoxy. I knew that would work just fine but I still wanted the centering rings because I wanted to vacuum bag them with kevlar to help hold them together. After a short call to Barry at LOC, I soon had the rings in hand. Time to get the kevlar going.

Here is how this works. I sanded and trimmed up the centering rings. They were very light and delicate some might even say fragile. Then I cut some .014 mylar disk and measured out some epoxy.

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Then I waxed the mylar disk to act as a mold release and provide a shiny finish on the kevlar then brushed on a very thin layer of epoxy onto the mylar. I applied the kevlar and rolled it out to smooth out the epoxy.

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Next I made the centering ring sammiches. The left one is ready to go, the right one still needs it's top.

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Next I folded the wax paper over the sammiches and placed them on a couple layers of paper towels to prepare them for the bag.

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Then I placed a couple more layers of paper towels on top and then placed the layup in the bag. The paper towels act as a breather, allowing the vacuum to pull the air evenly around the layup. I use a small strip of breather cloth folded in half over the layup to ensure the bag doesn't get sucked up into the vacuum hose. After I was happy with the placement inside the bag, a small amount of vacuum was pulled to see how things were working out. I used about 6" here.

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After I was happy with the way it looked all nice and smooth, I brought the vacuum up to 15" of mercury. All the time making sure no wrinkles were introduced. I could have stopped at around 7-8" because that is more that any clamp will ever give you but I wanted to give more. Ultimate remember?

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Lastly, I placed the layup on a piece of flat plywood with another one on top and weighed it down while it cured. The plywood or weight isn't really needed for the bagging process but they do ensure that layup comes out twist free.

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After 24 hours in the bag, it was time to open it up and peel back the mylars. For those of you who never tried vacuum bagging, let me tell you there is no sweeter sound than mylars being peeled off. It's like Christmas morning, unwrapping your favorite present. If you did your job right, you are left with a awesome finish and a very strong part. The whole process is very easy, just make sure you apply a smooth even coat of epoxy and the finish will come out pinhole free every time. As you can see, bagging doesn't have to be an expensive ordeal. I use a $30 hand pump (but it's a good one). My whole set up with pump, bag and clamps, vacuum connector, hose and the other little tid bits set me back about $60 and it will do everything a $300 pump will do. You just have to check on it every so often to make sure your bag isn't leaking. If it is, just give it a couple more pumps. For the record, it still had 15" over 24 hours later. Anyway, here is my centering rings before trimming.

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Wonder if the glass job will keep from breaking the CR's - but that's half the fun! Anyhow, get it done and make a road trip up to CATO - we drag race them every month!
 
Yup, glass would have worked just fine but I didn't have heavy enough to do the job. All I have is .75 oz glass on hand. The Kevlar was a pain to work with anyway. It's a pig to cut and sand, it frays like crazy and it gave me fits. Next time will be glass for sure just because it's easier to work with. Because it was a mess, I didn't bother with pictures after the trimming process.

Onto the build so I got busy epoxying the motor tubes together. No trick there, just glue two together at a time then glue the set of two together. After that I slipped the first centering ring onto the motor cluster and epoxied it in place. That was a chore to say the least. It was a long session of trial end error, trimming and sanding until it fit just right. Once that dried I slide the coupler tube over the tubes and glued it to the centering ring. Once that was dry I filled the voids with an epoxy and cotton mix then capped it off with the other centering ring.

After a good day of setting up, in a fit of motivation I went ahead and fit the fins. I rounded the leading and trailing edges then sanded the bevels in the roots. If you take your time and sand a good sharp bevel in the roots, the fins will lock into the grooves very tightly. Once they are epoxied in, they form a good strong bond. After the fins dried, I filled the center void with epoxy clay and waited for it to dry before I coated the top with epoxy to cap it off. All that is left to do on the fin can is fillet the fins and do the final sanding and priming. So far, so good.

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Now as far as the drag racing goes, I'll race it for sure but I won't expect to win. My Viper will be a touch heavier than it's opponents. I am building it to stand up to I power (hopefully) so it's going to be carrying some extra ounces.
 
Looks great so far! Enjoy the rest of the build - you should be up and flying soon. The drag races are more for fun then anything else...It's cool to see 6 of them going up at the same time...
 
Just remember ...loser buys!

Hmmm, mine is the white, yellow and red rocket (Team Trey)....seems to be the only one that was awake when the button was pushed....:clap:
So, what are you buying?? :cheers:

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hehehehehehehehehe and I got all four! No one even saw the apogee! I can tell you to leave the delay alone when you fly your viper on them :wink:
 
Now onto the next step. On this rocket, I wanted to try a zipperless design. Al suggested I make it a cold baffle design so I ordered a couple bulkheads and a coupler tube. Once the bulkheads came it, I wood filled the center hole the bagged them with glass just like the centering rings. Once they came out of the bags, I drilled two 3/4" holes in each bulkhead then cut some 4" long 18mm motor tube for the baffles.

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Here is the cold baffle joiner all glued up ready to instal. The tubes are offset 90 degrees to each other. At first I was concerned it may not let enough air flow through on ejection. After I got it glued up, I fit it in the body tube and blew through it. I was able to pass air through it easily so there shouldn't be a problem.

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The baffle test fit into the fin can assembly. It's starting to look like a rocket.

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The body tubes have been prepped by filling the spiral wraps with epoxy putty and sanded down. I still have some sanding and finish work on the fin can left to do. Then the whole thing needs some priming and a base color. I still haven't decided what I want to do for paint. Do I go with some sort of semi scale military design or do I break out the airbrush and do something different? The Viper has some surface to air look to it that leads it's self to a early 50's test type look. Who knows?
 
I got the rocket done for the most part. After I primed and sanded it, I put about five coats of white enamel on it. Now I just have to decide what to do for a trim scheme. I am starting to like the all white but still want to add something to make it pop a little....but what? I am seriously out of ideas. The best I have come up with so far is an AMRAAM sorta thing. I kicked around the idea of airbrushing skulls on it but the rocket is too classy for that. Any suggestions? I am really enjoying the look of the business end on this bird!

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I painted mine basic primary colors - chute is the third - blue. Part of a set of 3 2.6" rockets built together, others are a Graduator and a High Tech H45. Prepped and ready on 2 F240's and 2 D12's. Flew to 2000 feet via altimeter.

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You can't be serious.

Absolutely. I want to do a candy stripe and can't figure out how

ooooOOOOooooo. Pwetty.

You should seriously consider putting a bunch of H motors in there. Heh heh heh.

Why not? Not sure if there is a 24mm H, however I am holding 4 Ellis G37's I want to try. I did a 4-29SS on four H165's and a King viper on three K550's
 
Absolutely. I want to do a candy stripe and can't figure out how

I guess you can put it on some sort of lathe and roll some tape on it at an angle. What about moo cow? I know it's been done over and over again but it is still kinda neat looking.

Rocketjunkie, the plan for the build was to eventually stick 4 Cessaroni G's in it. The thing should go like stink. My first flight will be with the E75's then who know what after that. There are so many options with a 4 motor rocket.
 
First launch was today and what a day it was, a perfect sunny day with low wind. The plan was to stick four CTI E75's in it for the first flight but after I purchased the motors I had second thoughts. I decided to just fly it on two of them, that would keep the flight down in the 800 foot range and allow two flights for the day instead of one and done. I set the delay at 8 seconds for a perfect post apogee ejection. You couldn't ask for a better flight, straight and true coast to altitude with a very short walk recovery. These little CTI 24mm are freaking cool. The Vmax E's are fast and sweet, I love them! The second flight was a carbon copy of the first. I am very pleased with the way this thing flies. For the next flight in October I plan on flying two 3 grainers followed by four of the E's. That's gotta be the coolest thing about this kit is the flexibility it gives on launch, that or the way it looks.

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Bump for updates. :)

Considering a 4-29ss. What else have you tossed in here since that first day?
 
Bump for updates. :)

Considering a 4-29ss. What else have you tossed in here since that first day?

I flew it on 4 E75's Vmax's, 4 E22's Smokies, and 2 F85's Whites. It's a sweet flying rocket for sure. I really need to get it up on 4 F85's or 2 F85's and 2 G145 Pinks.
 
4-29SS is a great rocket. Light 2 motors and air start the 2nd set. 4 G75DM looks great under it.
Mr. Bob

Thinking 4 H250G, because I hate myself :mad:
I flew it on 4 E75's Vmax's, 4 E22's Smokies, and 2 F85's Whites. It's a sweet flying rocket for sure. I really need to get it up on 4 F85's or 2 F85's and 2 G145 Pinks.

mmmmmmmm G145's :) Bring it to LDRS and I've got a 24/6 case I'll add to the cause... :)
 
I got the rocket done for the most part. After I primed and sanded it, I put about five coats of white enamel on it. Now I just have to decide what to do for a trim scheme. I am starting to like the all white but still want to add something to make it pop a little....but what? I am seriously out of ideas. The best I have come up with so far is an AMRAAM sorta thing. I kicked around the idea of airbrushing skulls on it but the rocket is too classy for that. Any suggestions? I am really enjoying the look of the business end on this bird!

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Love those cluster builds...Nice job!!!
 
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