Madcow Terminator L3 Build

So, I've decided on a Madcow Terminator for L3. While not being very familiar with fiberglass , i did read the thread on epoxy, and with some West Systems, Rocketpoxy and some 120 grit paper, I feel as though it should be too difficult to get good/strong bonding.
The kit came in last week, and my first chore was unboxing and washing everything with hot water and soap. I was very impressed with the quality of the cuts, everything looked square with smooth edges. Madcow did forget to ship the tailcone CR, but was quick to ship a replacement when I let them know.


Then it was on to the MMT work. I ordered a few extra CRs for this kit, so that i could double-up where needed. The FWD CR will have (2) 1/4" stainless ubolts and will be doubled. Next 2 CRs will frame the forward fins. 4th and tailcone CR will frame the aft fins.



While I had the rocketpoxy mixed for the fwd CRs, I was able to bond the AV bay bulkheads too.


That's it for today, will let these cure overnight.

I've always liked the colors that madcow has. With shipping cost and just being a little more pricy, Its harder to consider buying one when I have local a local vendor. Maybe I'll buy one of their smaller kits. Good luck, hope all goes well!

I did my L3 with a Madcow T5 back in Dec. It's a great kit!
Here is a pic of her shakedown flight on a L800 CL

Keisling said:

View attachment 389129 I did my L3 with a Madcow T5 back in Dec. It's a great kit!
Here is a pic of her shakedown flight on a L800 CL

Click to expand...

Looks great! When you fitted the retainer, did you allow for a small gap between the retaining nut and the tailcone? or does it butt-up right against it?
I'm sure that I'll have lots of questions when I get into the "guts" of the build. For now, its all just fitting and figuring out what i need to buy.
I am seriously considering foaming the fincan, but will make that decision after the MMT and fins are all in place.

I affixed the Aeropack retainer so that it butted up tightly against the base of the tail cone. I can PM you a link to my construction package if you want to see how it was built.

I’m interested to see this build take shape! Looks awesome. Will you keep it the colors of the FG or are you thinking about painting it?

Keisling said:

I affixed the Aeropack retainer so that it butted up tightly against the base of the tail cone. I can PM you a link to my construction package if you want to see how it was built.

Click to expand...

That would be awesome! Thank you.

Ian A Dalton said:

I’m interested to see this build take shape! Looks awesome. Will you keep it the colors of the FG or are you thinking about painting it?

Click to expand...

I will likely be painting it, although I've not yet decided on any particular scheme.

Got a few things done in the past few days, and also discovered the quirks of West Systems epoxy. It began with attaching the Fwd CR to the MMT, and adding some fillets.


I noticed that my tried-and-tru Rocketpoxy did not get full saturation around the CR, or at least the "ring" did not appear continuous thru the translucent fiberglass. This got me concerned, and I decided to add some reinforcement.On the mid coupler, I mixed some West epoxy, and this stuff is like water! Definitely soaks in much better; and going forward, I think I'll be using more if it for initial bonding of fiberglass. Got a 1/4x20 stainless coupler and some threaded rod to connect the fwd. CR to the mid CR. Something like this:

I doubt it was needed, but will put my mind at ease. Hole in the mid CR will allow me to inject some epoxy thru a fin slot once the assembly is in the airframe.
I also received a shipment from Mcmaster containing the 5/16 stainless bits that will be used for AV bay. Drilled some holes in the bulkheads and did a quick dry fitting. Lots of room on a 5" bulkplate!

I suggest building it as clean as possible and leaving the paint option open? I've done similar and had limited success, if nothing else it "makes' you try harder..

Spent most of the weekend doing family stuff, but was able to get a few hours to do some building. I purchased a nosecone bay kit from APE, and am planning to use that for my tracker. I also wanted an easy way to turn it on/off, without having to disassemble everything. The Eggtimer WiFi switch seemed like a good idea to accomplish this, so I'll give it a shot. Assembly wasn't too difficult, although I did use a magnifier and could'nt imagine trying to do it without one. Took a few hours, but luckily got it all right the first time around.


Not much different than sweating copper. You do your best and then cross your fingers while turning the water on.
Other than that, I cut-out a fin template from foam board in preparation of doing MMT and fin install this week.


Hoping to begin internal fillets by end of week.

Some more progress. Firstly, I installed the MMT into the booster tube. It was pretty straightforward, basically slide the MMT in, pour some Rocketpoxy to the top of the fwd CR. After that cured, I used a small hole that I drilled into the mid-CR to inject epoxy in between the CRs and create a internal fillet.

Done in two steps, I was able to get both CRs. Hopefully, this is enough reinforcement for the stresses of deployment. Overall, happy with what appears to be good saturation for these 2 CRs. The thick band on the top CR is mostly due to them being doubled-up, as well as having a fillet on both the top and bottom. The lower CR is a single and only has a fillet on it's topside.

Next, drilled the switchband for 2 rotary switches and epoxied it into place. Pretty standard.

That should be it for today. Will let these parts fully cure overnight, and might possibly get started on fins in the next day or two.

Started bright and early today. First on the list was to get a fin on. Aside from installing the MMT; I usually consider putting on a fin as "really" building a rocket. For prep, I taped-off the area of the fin that I wanted to sand. Using a Bosch Oscillating tool with the sander attachment made quirk work of the sanding. The MMT was sanded thoroughly before being installed. I then grabbed a small triangle file and scored the root . I don't really know if it helps much, but figured that a little extra surface area can't be bad.

After cleaning everything with alcohol, i checked and rechecked fit to make sure I wasn't missing anything. Mixed some Rocketpoxy and did the 'ole double butter. By the time I got everything in place, fin template on and was satisfied with the alignment, I noticed that the unused epoxy had already begun to thicken. Time flies very quickly when your trying to take your time.

Not a huge fillet, but sealed well. I plan on doing a poured fillet with West/carbon once all of the fins are in place on both fin/MMT and fin/body tube intersections; then I'll seal-up that portion of the booster with a centering ring. All of that should take me approx. 2 weeks. I can always start work on other parts while the epoxy cures. Today, I started on a sled. Now waiting for some brass tubing to add between the aluminum angles.

Took a few days-off and went up to NH for most of last week. Got started again finishing-up the internal fin/MMT and fin/airframe fillets. I mixed up a fairly loose batch of West Systems, added some chopped carbon fiber and a pinch of 404 filler.This flowed well enough to get into entire length of fwd fins and leveled-off very nicely.

Put into a syringe, I gave each fillet approx. 7 cc's. After letting it cure for 10 hours, it was on to the next. Took several days, but finally finished. Really great to be able to shine a light thru the tube to inspect.

I also ordered a pair of Missileworks RRC3 altimeters and their T3 GPS tracker.
Tomorrow, I'll finally be closing-up the fwd portion of the fincan with a centering ring, and then its on to the tailcone assembly.

Slow going lately, with only a few minutes available each day to work on this build; but progress nonetheless.
My electronics came in, so I can work on those while epoxy cures.
Finally got the last two centering rings installed. Because the aft CR fit is critical for proper seating of the tailcone , the fin slots had to be shifted back a few millimeters. Once I was happy with the fit, I used some Rocketpoxy to secure it in place, making sure to position the other CR on the MMT first

Next step was to epoxy the last CR. I used the fins as a spacer and reversed some spring clamps top provide some pressure to the CR, ensuring that they were tight to the fins.



Once that fillet set-up a bit, I turned it over and took the opportunity to put some partial fillets on the opposite side, skipping where the fins will be. I will be injecting fillets once the tailcone is on, but that will be securing the fins.

The 151 rail buttons were also installed. The aft button is backed by a weld nut thru the body tube+coupler. Front button is simply a weld nut thru body tube, an inch above the forward most CR.
Both are Rocketpoxied into place.


Since I've already dry fitted the tailcone and fins, I think that I'll be installing them for the next few days, then it's on to external fillets!

OK, back to work.
Tailcone was installed, but first filed with holes in the fin slot for fillet injections. Just like the forward fins, the rear fins were sanded thoroughly, and the I filed random lines along the root edge to help adhesion.


Fins were then "double buttered" and inserted. I used 2 pieces of aluminum angle to hold them in place while curing.


Fin to MMT fillet were then injected. I used a combination of West Systems epoxy, 404 filler and chopped carbon fiber in a fairly loose consistency that flowed well. Approx. 5ml of glue for each fin.

Once I was finished with all of the fins, and the all cured, I went ahead and inject an additional 4ml per fin, but the taped the fin along the airframe and inverted the joint. Due to the shape of the tailcone, it would be difficult to get an even fillet along the entire length, however, I did rock it back and forth a few times, so I would imagine that I will get at least some epoxy to the high spot and a good fillet everywhere else, all while filling the hole that was used for the injection.
Last step iin this build session was to add a bit of epoxy to the tail end to reinforce that section close to the motor retainer. A flattened juicebox straw was just the right size. I added a full 10ml of Rocketpoxy here.

After some clean-up and light sanding, fillets this week.

coming along really well!

very nice

Nice progress. When are fillets going on?

Rich, I like what I see here, keep up what you're doing. At some point I'd like to see a photo of you working on the rocket as well. Are you planning on Certifying this year or next year? No worry really, just don't rush things.

Mdutch said:

Rich, I like what I see here, keep up what you're doing. At some point I'd like to see a photo of you working on the rocket as well. Are you planning on Certifying this year or next year? No worry really, just don't rush things.

Click to expand...

Thanks Mike.
The plan right now is to try for Oct./Nov., weather permitting.

Really clean work! Looks great.

Fillet time!
After sanding (again) and cleaning thououghly with acetone, I use a 3/5" PVC tube to mark the fillet lines on the fins and body.

Then, I taped the lines to keep epoxy from covering unwanted areas. This is my first split-fin rocket, and I underestimated how messy it would be.



Mixed-up 2 oz. of Rocketpoxy and started pouring. I normally would have let it sit for a few minutes to thicken a bit. But, since I was doing 4 at a once, I knew that I would be somewhat pressed for time. I used the same piece of 3/4" PVC and some alcohol to pull them.

After about 10 minutes I removed the tape. I used a gloved finger and some more alcohol to smooth the ends. Not perfect, but good enough to work with. Some Bondo and sandpaper to even them all out.


I'll be picking-up the motor casing this weekend, and will be epoxying the Aeropack retainer in place once I test fit it with the casing. I'm sure it will be fine, but trying to fix any fitment issues after its attached would be a nightmare. That will finish the booster section.
On to the AV bay and payload/nosecone build!

Those look great! Clean work!

Not much done this past week. I usually do some cycling charity rides this time of year, and getting out on the road and training takes a lot of time.
I did assemble the APE tracker bulkhead and T3 tracker. The quality of his work is perfect. I used some spare G10 sheet that I had to put together a little box that would house the T3's receiver. Basically just to keep it together with the battery.


Now, I am trying to figure-out how best to build the nosecone/coupler/bulkhead. For those that have done a similar build; where was the bulkhead attached within the coupler?
I am planning on epoxying it pretty much even with the base of the nosecone, and giving myself an few inches of payload space in return. I imagine the other options are:
Placing it even with the base of the coupler, which would take approx. 5" of payload space away.
Placing it at the forward end of the coupler, which would give me the most payload space, but also make accessing the tracker more difficult.
I do plan on permanently epoxying the coupler assembly to the nosecone; with the tracker there, i likely would never opt to add weight in that area.

It's funny you mentioned this..... I'm currently working on the same thing(for the same kit).
What I've done in the past is to; cut a coupler CR (I cut my own) either 3/8" or 1/2" thick to give it some meat to work with. I next drill the CR with 6 holes for threaded inserts, 8-32 size. Last I drill the 3" motor mount tube hole in it. I glue it into the coupler about 3" or so.
On smaller rockets I don't glue the coupler in, I drill and tap them with hollow set screws. They double as vent holes if you later choose to place an altimeter in inside.

Rich,

Have you picked your parachute yet? You may need the extra length of the coupler if you have a bulky chute.

Keisling said:

Rich,

Have you picked your parachute yet? You may need the extra length of the coupler if you have a bulky chute.

Click to expand...

Not just yet, although it will likely be a Fruity or Rocketman variety, so the packed size should be fairly small. Either way, the payload is still somewhat small to begin with. Putting the bulkplate even with the base of the coupler would give me less than 12" of usable space for chute, shockcord, etc..

Worked on wiring-up the altimeters and sled tonight. I am using wiring kits from Doghouse Rocketry, mainly because I like the locking connectors. On my sled, all of the connections will be done on the backside on the sled. Still some clean-up and more zip ties to be done.


Back of the sled.

Superb work on the sled Rich.

Oh and if your looking for recommendations on a load for your L3 in this bird? CTI M1830CS would be perfect.

GaryT said:

Superb work on the sled Rich.

Oh and if your looking for recommendations on a load for your L3 in this bird? CTI M1830CS would be perfect.

Click to expand...

Thanks! Looks like a fairly punchy motor. I actually have a CTI M1230 Imax all ready to go for L3.

Pace of building has slowed considerably for me the past few weeks. I have yet to order shock cords and chutes, but those will come once assembly is completed and i have a pretty good idea on final weight.
Other than that, I fitted and glued the Aeropack retainer in place, fitting the cap to just barely be short of the tailcone.
Slather on the JB Weld


Retainer fit


You can see in the pics that I've started with some Bondo work. I will be painting it, so might as well get the smoothest possible base. Primer will be sprayed this weekend, and I'll surely be able to see lots of imperfections. Sand/Bondo/primer, Sand/Bondo/primer, Sand/Bondo/primer.