L3 4" Frenzy

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mperegrinefalcon

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Hello peeps. I got my L2 certification about 2 weeks ago, and conveniently (and unfortunately for my bank account) a week after that, Madcow decided to have a sale on the 4" Fiberglass frenzy. I bought one and plan to do my L3 on it. I'm still waiting for it to ship, so no building just yet. I have some rough simulations, but I want to wait for the actual parts so I can enter their exact weights. I plan to fly it on an AT M685, and currently that is simming to about 18,000 feet (I live in Colorado so the starting altitude is 5,000 feet). I have a BRB 900 for tracking, and will probably use an RRC3 and an RRC2+ as my electronics. One thing I want to try with this build is putting an internal camera in it. I'm planning to put 3 1515 airfoil rail buttons attached with weld nuts epoxied into the air frame for this build.
 
The LiquidFyre camera shroud/carrier setup is pretty sweet, you may want to check them out if you haven't yet.
 
I just finished and flew a 4" DX3-XL which is similar in size. Two rail buttons is plenty, you don't need a third.
 
Hello peeps. I got my L2 certification about 2 weeks ago, and conveniently (and unfortunately for my bank account) a week after that, Madcow decided to have a sale on the 4" Fiberglass frenzy. I bought one and plan to do my L3 on it. I'm still waiting for it to ship, so no building just yet. I have some rough simulations, but I want to wait for the actual parts so I can enter their exact weights. I plan to fly it on an AT M685, and currently that is simming to about 18,000 feet (I live in Colorado so the starting altitude is 5,000 feet). I have a BRB 900 for tracking, and will probably use an RRC3 and an RRC2+ as my electronics. One thing I want to try with this build is putting an internal camera in it. I'm planning to put 3 1515 airfoil rail buttons attached with weld nuts epoxied into the air frame for this build.

Why get in a big hurry to do your L-3 You can learn a lot from flying at L-2 level.
 
Why get in a big hurry to do your L-3 You can learn a lot from flying at L-2 level.

I know, and I will be flying this on an L motor and K motors mostly, I just plan on eventually launching it on an M and want to document the build for the L3 cert.
 
I know, and I will be flying this on an L motor and K motors mostly, I just plan on eventually launching it on an M and want to document the build for the L3 cert.

I have the Broken Arrow XP made a few years ago and have flew it 2 times on the AT-M1297 with no problems at all. Plus on Ks and Ls so you should be fine.
 
Did you use 1515 or 1010 buttons? For a roughly 30lb rocket I would think 1515 would be best.

1010 rail and two buttons works just fine for that size. Many clubs have few (sometimes none) 1515 rails. I’ve used 1010 rails for 50 lb. rockets, but I would probably use 1515 for larger. Of course it depends on the anchor for the machine screw and the button material.
 
1010 rail and two buttons works just fine for that size. Many clubs have few (sometimes none) 1515 rails. I’ve used 1010 rails for 50 lb. rockets, but I would probably use 1515 for larger. Of course it depends on the anchor for the machine screw and the button material.
I like using weld nuts epoxied inside the body tube and the screw holding the button on I use blue loctite on.
 
For the MWP drag race featuring the Wildman Ultimate on N5800's, every rocket was fitted with 1010 buttons because there weren't enough 1515 rails. No mishaps from rail button failures that I recall. And we all know how aggressive the N5800 is... Just sayin... That being said, I use 1010's on 4"X75mm rockets. Anything bigger in diameter or 98mm motors gets 1515's.
 
Hey people,
The rocket finally arrived! I've done some test fitting and sanding, but I can't do much without my epoxy. I ordered it from Wildman, and it's been shipped so just waiting on its arrival. On another note, since an eyebolt won't fit so I will have to attach the shock cord directly to the motor mount tube. I picked up some 1/4" steel cable and some cable crimps. I was wondering if anyone had any experience using these kinds of supplies for HPR and if this is okay for this kind of application.
 
Hey people,
The rocket finally arrived! I've done some test fitting and sanding, but I can't do much without my epoxy. I ordered it from Wildman, and it's been shipped so just waiting on its arrival. On another note, since an eyebolt won't fit so I will have to attach the shock cord directly to the motor mount tube. I picked up some 1/4" steel cable and some cable crimps. I was wondering if anyone had any experience using these kinds of supplies for HPR and if this is okay for this kind of application.

I used a steel cable from the MMT to just below the top of the BT on my scratch built L1 rocket. It was SST cable and held up well to the ejection charges. I had to make a special tool to be able to coil it up and make it fit down into the BT. It's stiff and can't just be pushed down into the BT. Although it worked fine and held up well, it was a PIA to use and I've never used cable again.
 
Hey people,
The rocket finally arrived! I've done some test fitting and sanding, but I can't do much without my epoxy. I ordered it from Wildman, and it's been shipped so just waiting on its arrival. On another note, since an eyebolt won't fit so I will have to attach the shock cord directly to the motor mount tube. I picked up some 1/4" steel cable and some cable crimps. I was wondering if anyone had any experience using these kinds of supplies for HPR and if this is okay for this kind of application.

Dynacom did this as a standard on their kits. Should work
 
I've gotten some building done on this, quite a bit actually.

First, you must give your baby rocket a bath:

20180506_101605.jpg

Motor mount built:
20180521_172205.jpg20180521_172153.jpg

I decided to go for just using 1/2 inch kevlar simply epoxied to the motor mount tube. I saturated the kevlar with West Systems epoxy and used Rocketpoxy for the centering rings. I used a dremel tool to cut away the fully cured epoxy for the fins. The reason some of it is black is because I mixed up some Rocketpoxy with the black dye for fillets on a 38mm mongoose and just used the leftovers to do fillets on the centering rings.

20180521_185404.jpg

After sanding and cleaning I put some Rocketpoxy in the area the centering rings will go.

20180521_195217.jpg['
Inserting the motor mount tube. I twisted it once I put it in to make sure the Rocketpoxy got where it needed to go, and to line up the areas I ground down with the dremel. I left this overnight to cure. I just left the motor mount to cure flush with the bottom of the tube. I placed the rear centering ring in the bottom to make sure it is aligned. After six hours in front of the heater I injected a batch of West Systems epoxy in between the two upper entering rings to create a block of epoxy instead of a fillet. I did this for the upper centering ring as well. I let this cure, flipped the tube around and injected another batch in between the rings, this time for the upper ring.

20180523_210838.jpg
Once the West Systems cured, I tacked the fins in place with rocketpoxy. I aligned them with the good old NASA calibrated eyeball, and once the upper fins were tacked and cured, I tacked the lower fins on and used whatever I had that was straight to align the lower fins. This was after I used Rocketpoxy to secure the weld nut for the lower rail button and superglue to tack it in place. I will go over it a little later with some fiberglass cloth and West Systems. I made tiny fillets with Rocketpoxy to make sure the fins stay on. While this was curing I injected a syringe full of West Systems into the space between each of the fins. Unfortunately there was a little bit of an oversight. I forgot that there was a gap at the tip of the fins, so epoxy kind of leaked out a bit. Okay a lot. It went everywhere. I would have taken pictures but I didn't want to cover my phone in epoxy. I ended up using thin superglue to plug the gap. It was really cool actually. It smoked a little bit when I put it on the rocket, and immediately plugged the gap. I then just gloved up (I didn't have gloves on yet because I hadn't thought I needed) I then spread the epoxy around the body of the rocket in a thin layer. I was planning on doing this anyway to seal the FG, but this just expedited the process. It is curing now, and is nice and sturdy. I just need to do the internal fillets, reinforce the weld nut, and install the rear centering ring.

Till next time...
 

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Dynacom did this as a standard on their kits. Should work

Dynacom used it to connect the piston to av-bay. They were vented piston and did not leave the air frame. The travel of piston was very short, maybe 6in. It needed to be strong and handle the short stock and fire. It was not used as a connection to shock cord. The shock cord connected to the top of the piston.

Why use steel? It is heavy and not easy to work with. As long as it is serviceable, use Kevlar like most do.
 
I've gotten some building done on this, quite a bit actually.

First, you must give your baby rocket a bath:

View attachment 345123

Motor mount built:
View attachment 345121View attachment 345122

I decided to go for just using 1/2 inch kevlar simply epoxied to the motor mount tube. I saturated the kevlar with West Systems epoxy and used Rocketpoxy for the centering rings. I used a dremel tool to cut away the fully cured epoxy for the fins. The reason some of it is black is because I mixed up some Rocketpoxy with the black dye for fillets on a 38mm mongoose and just used the leftovers to do fillets on the centering rings.

View attachment 345120

After sanding and cleaning I put some Rocketpoxy in the area the centering rings will go.

View attachment 345119['
Inserting the motor mount tube. I twisted it once I put it in to make sure the Rocketpoxy got where it needed to go, and to line up the areas I ground down with the dremel. I left this overnight to cure. I just left the motor mount to cure flush with the bottom of the tube. I placed the rear centering ring in the bottom to make sure it is aligned. After six hours in front of the heater I injected a batch of West Systems epoxy in between the two upper entering rings to create a block of epoxy instead of a fillet. I did this for the upper centering ring as well. I let this cure, flipped the tube around and injected another batch in between the rings, this time for the upper ring.

View attachment 345118
Once the West Systems cured, I tacked the fins in place with rocketpoxy. I aligned them with the good old NASA calibrated eyeball, and once the upper fins were tacked and cured, I tacked the lower fins on and used whatever I had that was straight to align the lower fins. This was after I used Rocketpoxy to secure the weld nut for the lower rail button and superglue to tack it in place. I will go over it a little later with some fiberglass cloth and West Systems. I made tiny fillets with Rocketpoxy to make sure the fins stay on. While this was curing I injected a syringe full of West Systems into the space between each of the fins. Unfortunately there was a little bit of an oversight. I forgot that there was a gap at the tip of the fins, so epoxy kind of leaked out a bit. Okay a lot. It went everywhere. I would have taken pictures but I didn't want to cover my phone in epoxy. I ended up using thin superglue to plug the gap. It was really cool actually. It smoked a little bit when I put it on the rocket, and immediately plugged the gap. I then just gloved up (I didn't have gloves on yet because I hadn't thought I needed) I then spread the epoxy around the body of the rocket in a thin layer. I was planning on doing this anyway to seal the FG, but this just expedited the process. It is curing now, and is nice and sturdy. I just need to do the internal fillets, reinforce the weld nut, and install the rear centering ring.

Till next time...

Are you using any filler in the West System epoxy? If so what kind?

Just taping any hole that epoxy can come out will work. Keep alcohol on hand to clean up mess.
 
Great work on the build so far. I built my 4" Frenzy XL a few years back also with the intention of using it for my L3 cert. Due to life getting in the way... I still have not flown it! I am hoping to this year will be its maiden on a K550. I setup an Adept22 as primary and an Adept DDC22 as secondary in the avbay. Only time will tell if it flies this year or not. Good luck with yours!
 
Are you using any filler in the West System epoxy? If so what kind?

Just taping any hole that epoxy can come out will work. Keep alcohol on hand to clean up mess.

The only filler I used is the dust from drilling the holes in the fiberglass, so in reality no. The epoxy is purely there to hold things in place. I don't think it will need it because the epoxy is so strong on it's own, plus I don't have anything to fill it with. I'm using 105/206. If you think I should use a filler or reinforce the motor mount in some other way, what would you suggest?
 
Thanks! I plan on flying it on an M1850 for my L3 if my L3CC allows it. I will also be flying it on an L900 at some point. I will probably do a shakedown flight on something like a K400 or K630. I'm expecting about a 15 pound finished weight, is that about what you have?
 
For most anything other than wetting cloth or sealing a porous surface, that epoxy does need some kind of filler. For structural use, or for laminating wood, the West 403 adhesive filler is excellent. West 406 Colloidal silica improves the thixotropic properties of the epoxy (improves it's 'hang time'). West 410 micro-balloons makes for a nice 'fairing' quality to the epoxy. Kevlar fibers will yield a very tough and impact resistant fill. You can mix and match to suit your porpose, to some extent. Mix to the consistency that works. For structural filler, a pretty good amount of the adhesive filler in the epoxy mix will yield a big improvement in workability and also in strength, and will also make your epoxy go much further. Epoxy on it's own is not really that strong. There are other fillers, you do not need to use the West fillers. Read up on it.
 
The only filler I used is the dust from drilling the holes in the fiberglass, so in reality no. The epoxy is purely there to hold things in place. I don't think it will need it because the epoxy is so strong on it's own, plus I don't have anything to fill it with. I'm using 105/206. If you think I should use a filler or reinforce the motor mount in some other way, what would you suggest?

As stated, West System has some different fillers for different uses but some have cons as well. The high density filler adds weight but is strong and does not sand well. Some add some strength but sands well and adds in bonding laminating. Best resource is West Systems website.
 
There is a lot to be learned between L2 and L3, take your time and smell the AP as you go. Learning as you build is common and a good thing but trying to learn everything in 1 or 2 rockets is not a good thing. Don't rush through it, learn good techniques before starting a L3 bird.
 
Thanks! I plan on flying it on an M1850 for my L3 if my L3CC allows it. I will also be flying it on an L900 at some point. I will probably do a shakedown flight on something like a K400 or K630. I'm expecting about a 15 pound finished weight, is that about what you have?

That sounds about right but not 100% sure atm. I can try to weigh the sections and post later for you.
 
That sounds about right but not 100% sure atm. I can try to weigh the sections and post later for you.

My Rocksim file says 13.2 lbs but that is without electronics figured in, and estimated weight of the chutes. I weighed the parts just now and actual weight without the electronics, payload shock cord and connectors, and the chutes comes out to be 12.3 lbs.
 
The only filler I used is the dust from drilling the holes in the fiberglass, so in reality no. The epoxy is purely there to hold things in place. I don't think it will need it because the epoxy is so strong on it's own, plus I don't have anything to fill it with. I'm using 105/206. If you think I should use a filler or reinforce the motor mount in some other way, what would you suggest?

I used West 406 Colloidal Silica for the motor mount. I used West 407 Low-Density filler for the visible fin fillets due to ease of sanding and some added strength. Here is a quick overview on using them from West - [video=youtube;GITtvAp20pg]https://www.youtube.com/watch?v=GITtvAp20pg"]https://www.youtube.com/watch?v=GITtvAp20pg[/video]
 
Thanks for the help people. I have my current progress approved in person by my L3CC, and I am working on sanding the entire exterior with an orbital sander and 220 grit. I haven't done any more work with epoxy yet. For painting I am going to purchase an Iwata RG3 compact spray gun and use acrylic enamle automotive paints for color and seal that with a Urethane clear coat. Urethane paint is rediculously expensive, otherwise I would use that.
 
One question:
For the fillets I want to thicken up the rocket poxy a little bit. I picked up a box of different fillers at the launch I went to last weekend. I have colloidal silica, milled fiberglass, and carbon fibers that I can use. I've not used fillers in a build before, so what would the difference be between using these materials?
 
Thanks for the help people. I have my current progress approved in person by my L3CC, and I am working on sanding the entire exterior with an orbital sander and 220 grit. I haven't done any more work with epoxy yet. For painting I am going to purchase an Iwata RG3 compact spray gun and use acrylic enamle automotive paints for color and seal that with a Urethane clear coat. Urethane paint is rediculously expensive, otherwise I would use that.


If you are sod on Iwata, and are planning on purchasing the RG3 new, another option is to pick up an almost new LPH-400 with a 1.3 or 1.4 fluid tip, and the silver cap. You can find them from between $180- $225. I have 3 that I picked up this way, all were almost new. These are good guns.

Something that is often overlooked but very important, is the air delivery. A gun filter at the base of the gun is a very good idea. Also, a quality regulator at the base of the gun is all but essential, unless you have really short hose runs of large diameter HVLP specific air hose, likely made by Devilbiss, and with HVLP quick connect fittings. Otherwise, the regulator at the compressor is set at something high, like 40-60psi. The high quality gun regulator (not an air control valve, but an actual regulator, at the gun base is set to whatever you need for proper atomization. A setup like this is necessary with an HVLP setup (like most modern guns) in order to provide adequate air flow for good atomization Without it, you will struggle, and be hobbled, regardless of how good you are with a spray gun. This last bit is important. Lastly, if you plan on painting even a little bit, the 3m PPS system is awesome. It costs a little to get into, but in the long run, it saves money, as it costs quite a bit in solvent to keep a gun, and a big cup clean. With the PPS, he cups are disposable. This saves solvent, brain cells, and money.

IMO, base coat clear coats are easier to get an awesome finish with then single stage urethanes.

Pay close attention to the recoat times, and especially to the flash times of the clear. Follow the directions to the letter.

Have fun!
 
Thanks! I plan on flying it on an M1850 for my L3 if my L3CC allows it. I will also be flying it on an L900 at some point. I will probably do a shakedown flight on something like a K400 or K630. I'm expecting about a 15 pound finished weight, is that about what you have?

I did my L3 on a Wildman Extreme, which other than not having split fins is pretty similar. Mine ready to launch sans motor is 16.4 pounds. I think the K400 is likely a bit light on thrust. Might I recommend the AT K805 Green for this rocket. Good kick off the pad, and should get you about 4000’.

The M1850 would likely get you a little over 15000’. I did my L3 on the M1297, and got about 12600’.
 
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