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#### tHoagland

##### Rocket Builder
TRF Supporter
I've gotten so much value out of reading everyone else's build threads, I decided I would try one of my own. I'd caution anyone reading this that I have never launched a fiberglass rocket so everything shown in this thread will be untested and my best imitation of others' techniques. If you notice me doing something stupid, please speak up. I may not correct the issue but at least it will set you up for a good "I told you so" in a few months.

I'm going to be building the 3.0" Mad Cow Frenzy XL with 54mm motor mount that I bought on Black Friday. This was originally going to be my level 2 certification rocket but since I decided to push the limits of my cardboard Mad Cow DX3 and succeeded, this rocket no longer has any specific goals, other than to forward my skills.

I began by removing all of the parts, washing them with soapy water and then a wipe down with acetone. I know most build threads I've seen have used isopropyl alcohol for this final cleaning step but since I keep acetone in the shop but not alcohol, I used it instead. Everything was then arranged out for a pre-build photo op.

You'll notice that I bought the Aluminium bulkhead plates and for the initial build, I'll be using those. I do have some ideas for custom machined bulkheads that I'll do if I get a chance. Along the same lines, I'll be using a 3D printed AV sled. No details on that yet since I'm not sure what altimeter I'm going to use but I'm leaning towards an RRC3+. Also, I'll be leaving the option to install an Eggfinder tracker in the nose cone. Finally, I'll be ditching the included Nylon shock cord in favor of a Kevlar harness of some sort. I have a supply of 1/4" Kevlar that I'd like to use but have some concerns that it may be undersized. Any thoughts?

I'll be weighing components and building an open rocket file for this as I go. If there is interest, I'll post the final file and point out how, if any, it deviates from the Rocksim file provided by Mad Cow.

That's it for now....

#### noffie79

##### Well-Known Member
This should be fun! I'll be watching, good luck. And I think you'll be perfectly fine with 1/4" Kevlar. That's what I'll be using with my 3" Wildman Punisher.

#### Ccolvin968

##### Well-Known Member
Looks like you have a decent plan put forth. I'm working on my 2nd FG rocket now for my L2 and have a build thread started.
I'll be following you as well. It'll be nice to follow along with someone who is new at FG as well.
Best of luck!

#### tHoagland

##### Rocket Builder
TRF Supporter
Looks like you have a decent plan put forth. I'm working on my 2nd FG rocket now for my L2 and have a build thread started.
I'll be following you as well. It'll be nice to follow along with someone who is new at FG as well.
Best of luck!

Full disclosure, this is actually the second fiberglass rocket I've built. The other, a 1.6" DX3, is ready for priming. Since I haven't flown it yet, I have not had the opportunity to figure out how I screwed up and will repeat the same mistakes on this build.

#### timbucktoo

##### Well-Known Member
Staff member
TRF Supporter
Global Mod
It's one of my favorite rockets. You'll enjoy it too!

#### Forever_Metal

##### JustAnotherBAR
i was going to use the frenzy massive for my l3... Good Luck, will be watching!

fm

TRF Supporter
Subscribed

#### tHoagland

##### Rocket Builder
TRF Supporter
Since I have some vacation time to burn between now and the end of the year, I'm hoping to make good progress this week...

Today I made a couple of decisions and started gluing.

First I decided to go ahead and build the bottom of the nose cone as Mad Cow suggests, which is just epoxy the bulk head into the bottom of the coupler. In order to maintain access to the nose cone for an AV bay, I'm going to attach the coupler to the nose cone using 4-40 screw.

Then, after sanding the inside of the coupler, I used some epoxy clay I had sitting around to create a base for the bulkhead:

Installed the bulk head on top of the epoxy clay:

And then topped that with some RocketPoxy with black pigment:

I then turned my attention to getting the first two centering rings installed on the motor mount. This forced me to decide how to attach the recover harness to the fin can, and since there was no mention in the included assembly, instructions, I decided to tie a knot about 4 inches from each end of a 24" piece of Kevlar and sprawl out the ends:

I then filed a couple of notches into the top centering ring for the Kevlar to be routed through:

To make sure that I kept the centering rings from interfering with the fin tangs, I measured out the fin slots on the body tube. The photo below was mostly for me when I couldn't remember the measurements:

I then sanded the motor mount tube(MMT), marked the centering ring locations and made sure that the Aeropack retaining ring would slide on smoothly (required a fair bit of sanding).

Once I was comfortable with the plan, I went ahead and epoxied the top two centering rings (labeled I and II in the photo above) to the MMT. I'm not really happy with the results of the epoxying. I should have allowed the RocketPoxy to setup for 20 minutes before I began working with it. I had a lot of drooping and running which makes the top half of my MMT look like its been dipped into a bucket of epoxy. I'm going to hold off posting any photos until the epoxy cures...

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#### tHoagland

##### Rocket Builder
TRF Supporter
Since I'm planning to use a 3D printed AV sled, I thought I'd mention my other accomplishment for the day. I'd decided that I was doing enough personal prints on the 3D printer in the office, that it was time to have one at home. I bought one for my "kids" for Christmas and gave it to them early so that we could assemble and get it running this week while everyone was home from school and work. We assembled over the weekend and today moved it from its temporary home (the Kitchen Island) to its rightful place in the house; in the basement with me.

For 320, I'm really impressed with this printer. I had a few stumbling blocks due to a faulty control board (reconfigured the firmware to use the unused extruder 2 heater pins for heater 1) but other than that its surpassed my expectations so far. https://www.amazon.com/dp/B01ERDWSFU/?tag=skimlinks_replacement-20 Last edited by a moderator: #### [email protected] ##### Well-Known Member Love a split fin! I decided on a darkstar but almost bought this rocket too so look forward to your build. I didn't notice of you are roughing up the surfaces for better epoxy adhesion, if you are not - you might want to rough up those surfaces #### tHoagland ##### Rocket Builder TRF Supporter I didn't notice of you are roughing up the surfaces for better epoxy adhesion, if you are not - you might want to rough up those surfaces That's a good point. I forgot to rough up the bulkplate but I've used 60 grit on the motor mount tube and centering rings prior to adding epoxy. #### tHoagland ##### Rocket Builder TRF Supporter I didn't notice of you are roughing up the surfaces for better epoxy adhesion, if you are not - you might want to rough up those surfaces That's a good point. I forgot to rough up the bulkplate but I've used 60 grit on the motor mount tube and centering rings prior to adding epoxy. #### tHoagland ##### Rocket Builder TRF Supporter Finally, finding time to get back to work on this and documenting what I've done since my last post. In order to make sure the fins were aligned to the rocket body, I designed and printed a 3" alignment guide for 1/8" fins. Then because the Frenxy XL is a split fin rocket, I needed a way to align the two fins to each other and of course, the 3D printer was the right tool for that as well. View attachment 3in Rocket Fin Alignment Guide.stl View attachment Split Fin Alignment Guide.stl After using 60 grit sandpaper to rough up the fins (for the fillets), I used a 15 minute epoxy (Bob Smith) to "tack" the fins into place one set at a time, using the two alignment jigs to ensure the fins are properly aligned Next I needed to do the internal fillets for each fin. This is has been a challenge for me. I tried to use a 1/8" dowel rod to transport an smooth the epoxy but found it was impossible (for me) to get enough epoxy 13" into the tube to create a fillet. I then tried several "funnel" techniques to pour the epoxy into place, these also failed. I then tried to use a syringe with a piece of 10" rubber tubing to squeeze the epoxy into place found that the Rocketpoxy and Bob Smith Epoxy were too viscous for that (with out thinning). After a lot of reading on TRF, I finally decided that I would just drill holes near the fin base and insert epoxy with a syringe. This has given me satisfactory results although the resulting fillets are not continuous. At this point, I'm committed to finishing this kit with this technique, but would welcome other's opinions on how to better create internal fillets in tight spaces (~3/8"), keeping in mind the split fins and fins the reach 13" from the aft end. Below are pictures of the holes drilled and the resulting "fillets". I've finished 2/3 of the internal fillets and then will move on to the external fillets... #### tHoagland ##### Rocket Builder TRF Supporter On my last post, I made the photos larger instead of using thumbnails since I think it improves reading continuity but realized, after the fact, that for mobile users, it forces them to download the larger photo that they might otherwise ignore and could also slow down the page load. If you have an opinion on photo size for future posts (or in general) I'd be interested in hearing it... #### djpaulys ##### Well-Known Member I found tack down and fill with 2 part foam Sent from my iPhone using Tapatalk #### Zonie ##### Well-Known Member Since I'm planning to use a 3D printed AV sled, I thought I'd mention my other accomplishment for the day. I'd decided that I was doing enough personal prints on the 3D printer in the office, that it was time to have one at home. I bought one for my "kids" for Christmas and gave it to them early so that we could assemble and get it running this week while everyone was home from school and work. We assembled over the weekend and today moved it from its temporary home (the Kitchen Island) to its rightful place in the house; in the basement with me. View attachment 307670 For320, I'm really impressed with this printer. I had a few stumbling blocks due to a faulty control board (reconfigured the firmware to use the unused extruder 2 heater pins for heater 1) but other than that its surpassed my expectations so far.

Hictop is pretty good about sending replacements. Have you sent them an email? I got the other Hictop kit for Christmas, the one that uses 1010 rail for framing. Great little printers.

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#### patelldp

##### Well-Known Member
Finally, finding time to get back to work on this and documenting what I've done since my last post.

In order to make sure the fins were aligned to the rocket body, I designed and printed a 3" alignment guide for 1/8" fins. Then because the Frenxy XL is a split fin rocket, I needed a way to align the two fins to each other and of course, the 3D printer was the right tool for that as well.

View attachment 308935
View attachment 308936
Great idea on the fin alignment guide! I made one very similar for my LOC Ultimate. Due to it having 6 fins, I wanted to eliminate fin alignment guess work:

It worked really well, but relies on the fin being in a tube slot to keep it completely square axially. Next up is a simple design for a 3" MD rocket.

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#### Buckeye

##### Well-Known Member
TRF Supporter
Finally, finding time to get back to work on this and documenting what I've done since my last post.

In order to make sure the fins were aligned to the rocket body, I designed and printed a 3" alignment guide for 1/8" fins. Then because the Frenxy XL is a split fin rocket, I needed a way to align the two fins to each other and of course, the 3D printer was the right tool for that as well.

View attachment 308935
View attachment 308936
View attachment 308937
Very clever. Nice.

#### tHoagland

##### Rocket Builder
TRF Supporter
It worked really well, but relies on the fin being in a tube slot to keep it completely square axially. Next up is a simple design for a 3" MD rocket.

The STL file for the fin guide was attached to the post and should work on most 3" body tubes with 1/8" fins.