Hyperloc 835 Build (updated kit) - Level 2 kit

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downhill_D

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With my level 2 certification completed I have decided to build another level 2 rocket. I only have a Caliber ISP and really enjoy flying J's but wanted something a bit heavier for bigger motors and our clubs waiver. The Hyperloc 835 kit has been updated to use 3 motor mount rings and includes LOC's E-bay switchband. I wanted to challenge myself and add some changes to my normal HPR builds.

I will be fiberglassing the fins, I discovered the 1/8" fins are fairly warped and will need flattening. LOC had a solution for me. I was going to try and CUT some G10, then I asked LOC if they would cut some G10. Unfortunately they do not have the means to cut G10 anymore BUT they were willing to send me some precut fiberglass cloth to (cut-to-fit) the fins! I will flatten these using the same method I have before (one 45lb olympic weight on top of another-flat sides facing fins) only with fiberglass. I won't be modifying the airframe so the tabs will remain without glass.

Some tools I will be using and their purpose:
  • Magnet on a stick (installing rail button weld nuts)
  • Loctite 246 (grease resistant blue)
  • 300mm bicycle spoke for placing epoxy. threads cut off, can be wiped clean and reused
  • old 1/8" launch rod for placing epoxy for forward centering ring (wiped clean and reused)
  • Japanese backsaw (razorsaw) very good for making wood parts and centering rings fast
  • Polder digital Kitchen scale for weighing epoxy on rectangular cardboard pieces
  • 5 min BSI epoxy (stiffy into eBay, fin tacking)
  • 30 min BSI epoxy (tube assembly, fin flattening)
  • Rocket poxy (motor mount, fins and fillets)
  • JB weld epoxy (motor mount, eyebolts)
  • Thin CA glue (for strengthening tube edges and drilled holes)
  • 1500lb test
  • Krylon fusion spray paint
  • BBQ high heat paint (for switchband bulkheads and inside of payload tube for burn resistance)
  • A rectangular cardboard box with two half circle cutouts for a "secure" cradle
  • Drill and drill bits

Additional parts:
removable metal fasteners for switchband to payload attachment (need to be longer for stiffy coupler)
Eggtimer Wifi switch (to be built)
Eggtimer classic flight computer (to be built)
Additional vertical ply to increase e-Bay "real estate"
1010 rail buttons with weld nuts
1/4" forged eyebolt for booster to switchband attachment
a few other items may show up later on in assembly.
Venom brand Drone lithium batteries for all flights
Shear pins (for eventual DD)

I will attach pictures of the kit and my assembly (and techniques if I think they will help someone else) soon.
 

downhill_D

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The fiberglass cloth arrived from LOC today-clean cut edges, no fraying and cut to fit down to the tabs. Thank you LOC! You guys always take care of your customers! The fiberglass will go down on the fins on Saturday and I will include photos with how I am doing it but need to prep a well ventilated area ahead of time. I will be including photos this weekend, just not a lot of time during the week.

I also received my egg timer products today! I have been practicing and am ready to build the classic flight computer and a wifi switch. NOTE: do not short your wifi switch (I crossed "out" while powered on) or you will be buying another. I now have terminal blocks to fit so the problem will be solved. It was totally my fault, frayed wire from poor tinning, I now have a Hakko adjustable soldering iron and terminal blocks. Lesson learned and I am excited to learn how to build them myself.

I have done all the prep I can and am now trying to find a good solution for replacing plastic push rivets for some metal screws-anyone have anything they like to use? 3 fasteners (3 fins) like a 4-40 tube fastener from apogee (minimal surface mounted), internal t-nuts...I have researched a few options and ideas. The electronic Bay switchband kit from LOC uses a Stiffy coupler inside, full length, except to accommodate the bulkheads. A plastic push rivet (removable) is too short through the sidewall and probably too weak for keeping it together with the payload and deployment charges on a 4" tube SO I think I need to use metal screws now. What does everyone else use?
 

Theory

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The electronic Bay switchband kit from LOC uses a Stiffy coupler inside, full length, except to accommodate the bulkheads. A plastic push rivet (removable) is too short through the sidewall and probably too weak for keeping it together with the payload and deployment charges on a 4" tube SO I think I need to use metal screws now. What does everyone else use?
yup, metal machine screws into the nut of your choosing. must have some sort of metal nut for the screw to fasten too, simply running through the cardboard will work for one maybe two flights and then will fatigue to the point of failure. walk through your local home improvement store, or look on line. easy to find everything you need.
 

dr wogz

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I have:
  • Tapped a few holes in cardboard, but beefed up the hole with thin CA and then chased the threads afterwards. Not super strong, but does work
  • Glued (epoxy) a blind nut (T nut) inside the air frame. I do this typically for buttons, some models. I've also done it so the 't' part is inside the tube; not sticking out..
  • Glued (epoxy) a regular nut in place. A bit of grease on the threads of the nut (make sure it's ONLY on the threads) and a screw for the outside to hold it in place (again, a bit of grease on the threads, to ensure the epoxy won't glue the screw too!!)
  • And I've done the same as above, but with PEM nuts.. but you have a much smaller 'glue area'
  • Glued (epoxy or yellow glue) a small block of wood to the inside of the tube, then drilled & tapped the hole as needed. This is pretty strong! Even when Balsa is used (and a lot of CA!) And yes, glue-drill-tap-add CA-tap / chase the treads again.. The block of wood has also been shaped to confirm / fit the inside curvature of the tube..
I've seen someone make a hole, then tape a screw (with greased threads) to the air frame. They then gooped on thick epoxy over the screw threads, from the inside, essentially building a "nut" out of epoxy. This is where i decided to try inserting the nut, as to not rely solely on epoxy..

I've done a number of holes, tapped into wood. Usually a hard wood, and then flood the hole with thin CA to beef it up. This is fairly common to hold the wings on R/C airplanes..
 

Serac

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Cool! I'm building the same kit, although, with some changes.

I asked LOC for 1/4-inch fins instead of 1/8-inch. I have no plans for fiberglass at this time. I built up of the fins using the fin can approach instead of the instructions method. I like the kit, and working with LOC is great. However, I don't like the design of the fins. The tab that goes through the body tube should be longer. Lengthing this tab would make the motor tube stronger, and mitigate the fin warping problems we both experienced.

Mine will be about 8-inches shorter than the kit. I modified mine to use head-end deployment, with the main chute in the a nose cone assembly. We'll see how it works.

Right now I'm in painting hell. I don't like painting...
 

downhill_D

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Thank you all for the really good advice-found some M4 T-nuts that should work well and found a million other things I shouldnt buy as well. ;)
also, 4mm dome style screws with a washer on the outside. This should leave a nice low profile inside the switchband and outside the rocket.

Serac:
I agree the 1/4" would be a good width but they mentioned they wished it were 3/16". I am happy with 1/8" plus fiberglass-should be close to 3/16" maybe and super strong. although warped I really wanted more strength/stiffness for higher speeds. The tab length surprised me too, I was somewhat tempted to re-cut new ones with longer tabs from my sig ply-would only take a few minutes but I wanted to touch base with LOC and see what they could do. I am happy with a little fiberglass work but may scratch build the next one with G10 fins. I think the length of the fins and some good rocketpoxy fillets should make up for the stiffness outside. I am a big fan of 2 part foam on the inside after all fillets and MMT's are in.
 

downhill_D

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work etc. has delayed my build uploads but things are coming along nicely. I measured out 12 grams of 30 min bsi and the very light (thin) precut fiberglass cloth LOC sent me over the fin and sandwiched it in parchment paper. I spread the epoxy out through the cloth lightly and then firmly with a clean cardboard edge (LOC provided a solid hand sized cardboard square and one with a hole in it-I presume for spreading epoxy or making a fin guide). Once I had it sandwiched and cloth well saturated through I laid it upon a very flat ceramic tile (12" x 24") and then laid one tile face down over this gently. I applied 70lbs of olympic weight on top while it cured. Once finished the fins were much flatter and the fiberglass was invisible and well pressed into the ply with a matte finish. I removed all excess fiberglass edges (about 1/8"-1/4" at the most) outside with a respirator and goggles and clothes I dont care about using a sanding drum on a Dremel-took 5 minutes.

2 fins still need a little straightening though, much improved but the epoxy, fiberglass, my press or all were not strong enough to hold the fin perfectly flat but this is 1/8" ply I was trying to flatten. I will be using rocket-poxy for the fillets and feel this should amend any issues with uncontrolled roll or direction in flight due to fin curvature. I will have to update with pictures later.
 

wsume99

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I will be using rocket-poxy for the fillets and feel this should amend any issues with uncontrolled roll or direction in flight due to fin curvature.
How are fillets going to correct a curved fin? They may help prevent flutter because the fins are thin but if the fin is curved the fillets aren't going to straighten it. Am I missing something?
 

downhill_D

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How are fillets going to correct a curved fin? They may help prevent flutter because the fins are thin but if the fin is curved the fillets aren't going to straighten it. Am I missing something?
yes, you are correct and yes, you are missing something. more info.

There is one more round of flattening to go with epoxy because I can still see some of the cloth in some areas and the curve is alleviated quickly when I bend the fins slightly at the root. I think after this it should be acceptably straight/flat.
 

downhill_D

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I am going to use an eggtimer classic as a flight computer for this rocket. I built about 75% of the eggtimer classic computer last night-way easier than I hyped myself up to be-however in preparation I DID use youtube videos prior, flux, practiced on random old electronics and used an adjustable soldering iron.
 

downhill_D

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I Re-coated the fiberglass covered fins tonight to fill in the rest of the cloth where it didn't quite saturate the first time. I decided to coat both sides at the same time so by morning I will know if they are flat enough. I think it will work but in case it doesnt I found a local plastics company that stocks g10 and is much cheaper than paying shipping through mcmastercarr. Mounted the eggtimer computer onto the av-bay board.
 

downhill_D

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I assembled the switchband. This utilizes LOC's very heavy coupler (stiffy), which makes the switchband and payload very heavy walled. nice. I marked the switchband for T-nuts using the open aft body tube. The T-nuts were modified with a file and the payload bay is attached using 3x M4 machine thread dome cap screws.
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downhill_D

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I pulled the T-nuts into place using an old bearing puller and a longer M4 screw. The screws can then be aligned with the fins nicely befoe flight.
 

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downhill_D

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I epoxied the foremost motor mount ring into place using JB weld and drilled for a U-bolt to support the greater separation loads and high heat capacity.
 

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downhill_D

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181.JPG
The fins were fiberglassed using 30 min BSI weighed and pressed between two ceramic tiles and 90lbs of weights for the full cure. The first time it made a difference but not a great one. I think longer curing laminate epoxy would be a better approach but I did a second coat and feel the fins will align well enough for stable and probably straight flights.
 

downhill_D

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The fins are thicker now, totalling about 3/16"
185.JPG
so I modified the fin slots for the larger widths.
 

Tim51

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Following with interest. A bloke at our club flies the 835's bigger sibling (the 1600) on hybrid M motors - always a spectacular sight. The Hyperteks are a nice design - very easy on the eye IMO.
Good luck with the L2 cert.
 

downhill_D

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Will you be launching this on a hypertek?
I will not. I looked into the system and its a really cool setup but I like composite propellants a lot. I did like that their system seems very simple regarding reloading. Is the hypertek motor the reason behind the extra coupler and body tube extension to the aft body tube (added length the body tube)?
 

downhill_D

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Following with interest. A bloke at our club flies the 835's bigger sibling (the 1600) on hybrid M motors - always a spectacular sight. The Hyperteks are a nice design - very easy on the eye IMO.
Good luck with the L2 cert.
Yes the 1600 is a big one, almost got that one but wanted a bit less weight for now. I already have my level 2 but thanks, I am building my second level 2 rocket to clarify :D
 

Tim51

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I will not. I looked into the system and its a really cool setup but I like composite propellants a lot. I did like that their system seems very simple regarding reloading. Is the hypertek motor the reason behind the extra coupler and body tube extension to the aft body tube (added length the body tube)?
Yes the HyperLocs (erroneously called it a hypertek in my ealier post) were designed with a longer MMT / booster to accommodate the run tank and combustion chamber of a hybrid motor.
 

downhill_D

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So I would like to feed off everyone here on this one regarding the extension on the booster tube. There is a regular coupler with this 11" extension and it all gets glued together. I have understood that a good K motor can actually crush a high-power tubing at a regular coupler junction (why LOC has the stiffy coupler now) at speed.

Would you:
1-skip the addition since the payload is attached with a switchband made of the thicker stiffy coupler
2-add it and not worry about it (you have experience running a K or higher)
3-use a stiffy coupler, add it and worry about the chute and lines hanging up on the extra edge inside the booster :rolleyes::eek:
4-finish the rocket without the extension
5-add the parts and glass this baby!
6-make the extension removable and fly without it when using bigger impulse motors (running simulations with changes for the reduction of course)

what would you do?

Thanks!
 

wsume99

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I don't think you can compare the strength of a glued coupler joint to one that isn't. I think as long as you use a laminating epoxy so that the joining pieces are thoroughly wetted then you will have no issues. Of course I have no actual experience flying on K motors but that's my opinion.
 

downhill_D

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I don't think you can compare the strength of a glued coupler joint to one that isn't. I think as long as you use a laminating epoxy so that the joining pieces are thoroughly wetted then you will have no issues. Of course I have no actual experience flying on K motors but that's my opinion.
yes on the epoxy but the wall thickness at a new joint is where I think people were concerned. I think you might be right but let's see what others with experience with K's and L's think, there is certainly data on it somewhere. I only have experience to baby J's right now but am not afraid to overbuild this but kind of want to keep the original length. Someone here knows.
 

downhill_D

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Moving forward I am going to order the extra thick coupler. LOC wouldn't make it if it didn't have a purpose and this booster joint is that purpose and if you can make a reinforcement, why wouldn't you? Thanks to my club members for making the obvious more obvious at times.

I removed more glassine from the motor mount and JB welded the second ring into place after double checking fin fit. I added more holes to the middle centering ring to allow the first pour of foam through after the fins are aligned and in place with epoxy fillets at the MMT. This will leave just one more CR and the aero pack retainer.
 

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