Punisher 3 for Level 1

HVArcas said:

i built my punisher heavy, flies great/easy/fun/trackerless on high thrust motor deploy I motors with a 38mm adaptor (then it takes 54mm6G XL when we want to go gonzo)

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How heavy did yours end up? What did you do to make it more beefy? I am hoping to be able to fly it safely on an H to 1500 or so, but I will see what the sims suggest after the build is complete. I'm not aiming for any records, so I don't plan in building super light.

One of my eggtimer minis powers up, blinks red, but never get the amber led blinking. It seems to get a fix no problems and I walked straight up to a rocket 2km away last weekend that had gone out of sight at 5000+ feet.

HVArcas said:

those are a lovely form factor but a bit expensive and we have had a decent number of them fail. not like they are junk or anything, but, definitely not as fail/fool proof as the missileworks, where there is basically nothing to go wrong

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How did they fail and under what conditions?

NateB said:

How heavy did yours end up? What did you do to make it more beefy? I am hoping to be able to fly it safely on an H to 1500 or so, but I will see what the sims suggest after the build is complete. I'm not aiming for any records, so I don't plan in building super light.

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I cannot recall and it is out of my hands now, but I think it was right in line with the 3 inch Darkstar which is basically the same rocket but longer.

mpitfield said:

How did they fail and under what conditions?

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This was a >100k project and subject to serious abuse. Oh and it lived in a foggy/humid environment when not flying. We had probably 6 switches on board and have needed to replace 2 over a course of several years. I suppose now that you mention it, the failure easily could have been wiring instead of the switch itself, but the act of replacing it fixed the problem.

I drilled 3 - 3/32" holes for 2-56 shear pins in the nosecone and drilled a 1/8" vent hole. I also drilled a small keyhole mark in the vent band to ensure proper alignment when I insert the shear pins. My son was begging to help and let me use his little table today. His small fingers did help get the shear pins in and out.

Now the nosecone is all done and I'll work on the booster. It looks like I might be able to attend the launch at Three Oaks in April. I may not have good weather to paint before then, but should have the rocket complete. I have some mid powered rockets that would be fun to fly there too.

I also drilled holes for the rail buttons using a piece of aluminum angle for alignment. My son did his part by threading them in with a screwdriver. He was proud to help. This is the second rocket he has helped me with, the first being an 18mm Mach 1 Exiter. The booster side of the coupler was a bit loose. Rather than use tape, I found the best fitting spot and added 3 more shear pins. All that is left now is the motor mount and fins.

NateB said:

I got some more work done today. The aluminum bulkhead plates were drilled and the terminal blocks with charge wells were installed. I might swap out the ring terminals for spade terminals on the forward end to make it easier to remove the sled.The leads are long enough to remove the bulkhead plate and charge the battery, but a quicker disconnect might be nice down the road. I also need to get some eye bolts for the recovery attachment. Lowes and Menards didn't have anything that would work. Next time I made an order from McMaster, I'll add some.

Everything fits in the nosecone, but it is still too tight. I'll have to sand the nosecone end of the coupler and then drill holes for shear pins.

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Hi Nate. Where did you get the charge well/ terminal blocks? I've seen them on somebody's web site but can't remember where. I have a Darkstar Jr. With the aluminum bulkheads. Right now I just use glove fingers, the charge wells look a lot nicer.

Those are doghouse rocketry/binder design. I love them

Jay Dub 4009 said:

Those are doghouse rocketry/binder design. I love them

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Thanks! I couldn't remember where I had seen them. I got some of the wiring kits from them and they are great.

I do like the clean look of the charge wells and the convenience of how the terminal posts are wired. They also seem like the wiring is secure and unlikely to loosen during flight.

For my Darkstar Jr, I'm going to keep the bay super simple with a Quark and e-match run through a well nut. I like the charge wells told, but I think they would be big for a 2" rocket and make everything too cramped.

I made some progress on the motor mount. After sanding the MM, the retainer was secured in place last night with JB Weld and allowed to cure. I also painted one side of the rear centering ring black.

The harness is 1" flat kevlar and the forward CR was notched to allow it to fit. Next was to fit the fins in place, tack the centering rings with CA and double check the fit. Once I was happy with the fit l, mixed up a batch of Rocketpoxy and had a cup of coffee. The kevlar harness was glued to the MM tube with a healthy epoxy capsule. I placed a fillet around the top edge of the forward CR. Everything is curing now.

The Rocketpoxy is probably 3 years old, maybe older. The resin was quite stiff and difficult to mix, but it did end up mixing just fine, just more stiff than normal. It won't flow, but is easily spread and molded. I think if I use the same batch for the external fillets, I will soak each tub in hot water before I mix it up.



The last decision is to inject internal fillets or trust the double/triple dip method. People make these MD with 3" motors, so I think a healthy amount of epoxy buttered on the root edge will make the fillets I need for H and I motors.

NateB said:

I made some progress on the motor mount. After sanding the MM, the retainer was secured in place last night with JB Weld and allowed to cure. I also painted one side of the rear centering ring black.

The harness is 1" flat kevlar and the forward CR was notched to allow it to fit. Next was to fit the fins in place, tack the centering rings with CA and double check the fit. Once I was happy with the fit l, mixed up a batch of Rocketpoxy and had a cup of coffee. The kevlar harness was glued to the MM tube with a healthy epoxy capsule. I placed a fillet around the top edge of the forward CR. Everything is curing now.

The Rocketpoxy is probably 3 years old, maybe older. The resin was quite stiff and difficult to mix, but it did end up mixing just fine, just more stiff than normal. It won't flow, but is easily spread and molded. I think if I use the same batch for the external fillets, I will soak each tub in hot water before I mix it up.

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The last decision is to inject internal fillets or trust the double/triple dip method. People make these MD with 3" motors, so I think a healthy amount of epoxy buttered on the root edge will make the fillets I need for H and I motors.

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I injected internals with West and chopped carbon fiber for my 3" Darkstar, only because I hope to fly an "L" someday

NateB said:

2019 came and went and I never started on my Punisher 3 I intended to do my level 1 with. When the build is complete, I hope to fly it on a Loki H-144.

As is often the case, family life and work responsibilities pushed some hobbies to the side. I had a big change in my job assignment and a lot of educational responsibilitie last year. Now, I have 1 class this semester to finish my degree and it looks like I might stop swing shifts and go to mostly days in March or April. I'm crossing my fingers, but I should have more time and energy for hobbies this year.

This was my weekend for night shift and most of the shift we have had 300' ceilings with snow and ice coming coming down. With poor weather forecasted all weekend, I had packed up some things to keep me occupied.

Everyone starts with the motor mount, I'm starting with the electronics. First up, was my Eggtimer Classic. This is my first time soldering anything other than bike cables and connectors on wires. I went slow and step by step per the instructions. It took me a little over 3 hours, but I have a complete altimeter. I did not bring a battery or the parts for my sled, so I have not added the pigtails for the battery and switch yet. My eyes need a break anyway. I might do that later today or my next shift. Then comes the moment of truth to see if the board powers up and allows me to program it.

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I can relate with things getting in the way.

tOD said:

I injected internals with West and chopped carbon fiber for my 3" Darkstar, only because I hope to fly an "L" someday

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I do want a 3" Darkstar and I might use it to get my Level 2 someday. I don't see myself flying very many K or L motors, maybe even just once. I'd probably use my Level 2 to launch more G sized sugar rockets than anything.

I went ahead and drilled holes to inject the internal fillets. Right now, the rear CR is tacked on with CA so it is flush against the retainer. I want to make sure I have a good fillet of epoxy on top of the rear CR since it bears stress from thrust during launch. I wasn't positive that a heavy coat of epoxy along the root edge and double dipping would allow enough epoxy to run off and make a fillet around the CR. Injecting epoxy should ensure I have plenty where it needs to be.

After sanding the inside of the body tube where the CR rings attach, I epoxied the motor mount in place and left to cure over night. I have had trouble getting epoxy outside of where I want it to be using a long stick to reach up inside the body tube. I noticed that the fin slots are just wide enough for a cut down IV hub threaded on to the Leur lock of a 20ml syringe. I slide the motor mount most of the way in place, injected 5ml of epoxy in one of the slots and a small amount came out of the other 2 holes. After rotating the MM in place and ensuring the kevlar strap for the harness is clear of the fin slots, I have a perfect fillet of epoxy on top of the forward CR. A paper towel soaked with alcohol cleaned the fin slots the motor mount is in place with no mess and no epoxy where it shouldn't be.



I also updated the Sim file with all the weights of my components so far. The harnesses for the drouge and main are ordered and not accounted for yet. I'll have to adjust the final weight for fillets and paint as well.

This morning before the fog lifted I assembled the GPS module for my Eggfinder LCD and it appears to be working just fine. I also added the Bluetooth module and my Android phone cannot find it to pair. I'll have to troubleshoot that this evening when I get off work.

I came home from work after a 6 hour long meeting mandated by the FAA and found a box from US Composites just inside the door. I'm glad it came before my wife left for work so it wasn't sitting out all day. There was no time to start the fins tonight, but I did get a fin guide template printed out. Hopefully tomorrow O can find some foam board to cut out the guide and get the fins on.

tOD said:

I injected internals with West and chopped carbon fiber for my 3" Darkstar, only because I hope to fly an "L" someday

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Mine takes L935s and L640s without thinking twice, cannot imagine you having any issues whatsoever assuming good workmanship.

I took advantage of nice weather and painted some other projects this afternoon, so the fins didn't get mounted. I did get a chance to tweak the electronics bay to tidy up the wiring, improve strain relief, and swapped out the ring terminals for spade terminals in order to remove the sled easier. I couldn't find these small terminals locally, so I had to pay Digikey as much to ship some odds and ends to me as the parts cost.


I'm still waiting on official confirmation about my schedule change, but I am tentatively planning on a launch and cert flight at Three Oaks in April. I also finally joined Tripoli tonight so I can buy my motor and cert.

Awesome!

btw high G flights will bend those transistors on eggtimer classics - you can mount them backwards, support them in some way, or maybe simply make sure they will not short on anything and not care..

Thanks for the heads up about those transistors. I don't think that will be an issue on the first couple of flights, but might when I go higher and faster. Now that I am more confident in my ability to solder these kits together, I will most likely be using a Quantom and Quark on future builds.

Back on this build, I got a layer of primer on the nosecone yesterday. Today was too cold to paint anything else. I wasn't happy with fin template I printed out and cut from foam board, so I picked up and cut MDF for a fin alignment jig. I have an old table saw that doesn't hold very true, so I'm going to borrow my wife's step-dad's saw to make the beveled rip. Slowly, but surely this will be ready to fly in a month.

My fin alignment jig is complete and I tacked on one fin with Rocketpoxy which is now curing.

The last fin is now tacked on. I'll work in injecting the internal fillets over the next few days. At least it looks like a rocket now.

Neutral-cure RTV is good to use on the transistors. Just buttress them to the components and board nearby. Vibration will snap the legs off at the PCB. Make sure you use neutral-cure. If it smells like vinegar, don't use it.

I injected the first set of internal fillets tonight. This was my first time using US Composites Epoxy and I think I mixed it to thin. I added 1 tablespoon of milled fiber to 2 oz of mixed epoxy. It managed to find every gap between the fins and the slots and is dripping out where I really didn't want epoxy. Hopefully it sets up enough soon to not run so bad so I don't have a ton of sanding to do later. I'd like to be able to keep up wiping up the drips with some alcohol.

NateB said:

I injected the first set of internal fillets tonight. This was my first time using US Composites Epoxy and I think I mixed it to thin. I added 1 tablespoon of milled fiber to 2 oz of mixed epoxy. It managed to find every gap between the fins and the slots and is dripping out where I really didn't want epoxy. Hopefully it sets up enough soon to not run so bad so I don't have a ton of sanding to do later. I'd like to be able to keep up wiping up the drips with some alcohol.

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Use masking tape to seal off any possible leak areas

NateB said:

I injected the first set of internal fillets tonight. This was my first time using US Composites Epoxy and I think I mixed it to thin. I added 1 tablespoon of milled fiber to 2 oz of mixed epoxy. It managed to find every gap between the fins and the slots and is dripping out where I really didn't want epoxy. Hopefully it sets up enough soon to not run so bad so I don't have a ton of sanding to do later. I'd like to be able to keep up wiping up the drips with some alcohol.

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I have quit using anything but 1:1 epoxies with some milled FG when injecting fillets. Even with tape, the thin epoxy seeps down/through the fin area where you want it to be and instead migrates to the current low point in the airframe. To get the thicker 1:1 epoxy to inject you need to heat it while mixing (oh, and it needs to be a slow cure like T-88, although I have been using a golf shafting epoxy brand I love lately, Brampton). Just dip the mixing cup in a sink (or container) of hot water and stir. Gets soupy enough to pour into a syringe, then inject; but your job is not over yet. You then take a heat gun set on low and apply heat from a good distance, say 12", for 20 to 30 seconds while tilting airframe up and down (this also helps any extra epoxy that didn't enter the airframe when injecting due to back pressure, to run through your hole). Do this two or three times and you will get a good even distribution of epoxy along the internal fillets, but 1) it doesn't get hot enough to loosen the already cured tacked-in fins (typically done with 15 min. epoxy), and 2) just as good, the slow cure epoxy stays thick enough not to make its way through any stray cracks you may have from tacking your fins.

My 2 cents. The key to injecting is making sure the fins are fairly well sealed before injecting. I make sure the fins are snug inbetween the CR's and the CR's are well sealed to the MMT. Trial and error with the fit. Once achieved, pretty much any epoxy can be used with no fillers.

I woke up this morning and didn't find a major extra mess or drips on my fin can. The fins were tight to the centering rings, they just needed a few light taps to seat in between the CR and against the MMT. The gaps where saw the leaks were the fin slots. I masked them for the next set and it appears to be holding the epoxy so far. It will just take some practice using what I have instead of 30 minute BSI epoxy.

The next kits I have to build won't use injected fillets, double dipping the fins on Darkstar Mini and some surface mount on a couple Mach 1 kits will let me get used to the US Composite Epoxy.

I have double dipping for ths last 3 years. It has worked out well for me