Wild Child Build - Test Round

After the demise of my AeroTech Initiator, I needed something to replace it in my fleet.

After looking to see what was out there, it seemed that the best for me would try the Wild Man's Wild Child. It had things that were looking for, such as:

• filament-wound airframe and MMT
• simple, clean design
• G10 fins
• VK nose cone

So I called Wild Man and ordered it, and about a week later the box arrived.

The airframe is 24" in length, with an outside diameter of 1.60".

It should be a fun build.

Greg

The first order was to make sure that the aft end of the MMT was cut square. This was because I planned to add an Aero Pack retainer.

I used card stock with a long edge cut with a straight edge. I wrapped the paper around and saw that this end was square, so I marked it with a Sharpie. It isn't necessary for the forward end to be square, so it was left alone.

The MMT was now ready to have the Kevlar recovery harness epoxied to the MMT.

I did the usual sand and wipe with alcohol or acetone. I marked the area for the MMT.



I mixed up some Loctite 5 minute epoxy, then added some chopped Kevlar to the mix. I then placed it on the MMT and placed the Kevlar on it. I then mixed a second batch of Loctite 5 minute epoxy, with some milled fiber, then placed it on the top. Then I set it aside to cure for a bit.



Greg

After it cured a while, it was time to add the CR's.

I like the work that Bill at BMS does, so I ordered some 1/8" and 1/4" thick CR's so I could figure out what I wanted to do.

Ultimately, I settled on a MMT with 3 CR's instead of the 2 that came with the kit.

The placement of the forward and aft CR was going to be easy: the far forward part of the MMT and the aft end of the MMT.

The key was to figure out where the mid CR was going to be placed. After some time in Excel, I figured the best place was to aft the aft edge of the mid CR at 5.875" from the end.

I also had to notch the forward and mid CR to accommodate the large gap caused by the recovery harness.



I wanted a positive stop for the mid CR to rest against, so I cut some card stock and glued it with rubber cement against. It is not meant to be permanent, just good enough for the moment.



I then mixed Aeropoxy adhesive and added milled fiber to it. I then added the mid CR.



I then added the forward CR and then secured them with masking tape, then set them aside to cure.



Greg

Now, on to the fins.

The fins are 0.064" (1.6mm) thick, and since they are so thin they don't need to have any kind of airfoiling.



However, I'm a little on the OCD side so I couldn't leave well enough alone.

So I ordered some 1.6mm carbon rod from RC Foam. The idea was to glue them on the leading and trailing edge. So I cut 3 rods to length for the leading edge and 3 rods to length for the trailing edge.



I placed masking tape on the end to mask it, then discovered that there was about a 1mm lip from the tape. I thought that would be good to help keep both the glue and the rod in place.



I then took some of the leftover epoxy from the CT/MMT endeavor, and placed it on an a side of the rod and placed it in the gap between the sides of the tape.

I cleaned up the excess with acetone and set them aside to cure.



I only did the leading edges, since I thought it would be asking for trouble to do the trailing edges at the same time. So the trailing edges will have to be tackled at a later time.

Will it work? Probably. Will it last a lot of flights? We will see. But that's rocketry.

Greg

GregGleason said:

After it cured a while, it was time to add the CR's.

Ultimately, I settled on a MMT with 3 CR's instead of the 2 that came with the kit.

I also had to notch the forward and mid CR to accommodate the large gap caused by the recovery harness.

I then added the forward CR and then secured them with masking tape, then set them aside to cure.

Click to expand...

Not sure it it makes much difference, but I'm thinking it would be better to install the CRs first as single pieces so you don't have to tape them together to maintain the correct OD. After CRs are dry, notch the CRs with a dremel or other appropriate tool and install the shock cord.
Like I said, probably doesn't make any difference, but putting the CRs on first might allow for fewer chances for problems with fit in the BT later.

Something else you might want to try is wrapping the MMT and shock cord loosely with blue tape to make sure none of the epoxy hardens too high to fit in the BT. Wouldn't be problem with a larger OD rocket, but this one doesn't have much room to play with. Just a thought.

I found it much easier to file a small notch and install the rings over the shock cord, and then epoxy the cord. flat braided kevlar is not overly thick. hard to damage a wildman rocket .
rex

Handeman said:

Not sure it it makes much difference, but I'm thinking it would be better to install the CRs first as single pieces so you don't have to tape them together to maintain the correct OD. After CRs are dry, notch the CRs with a dremel or other appropriate tool and install the shock cord.
Like I said, probably doesn't make any difference, but putting the CRs on first might allow for fewer chances for problems with fit in the BT later.

Something else you might want to try is wrapping the MMT and shock cord loosely with blue tape to make sure none of the epoxy hardens too high to fit in the BT. Wouldn't be problem with a larger OD rocket, but this one doesn't have much room to play with. Just a thought.

Click to expand...

Well Mr. Handeman, you were correct. Cutting the CR altered the OD just enough where there is too much slop.

So, I need to bump up the OD so that the CR fits properly. Any ideas?

Greg

GregGleason said:

Well Mr. Handeman, you were correct. Cutting the CR altered the OD just enough where there is too much slop.

So, I need to bump up the OD so that the CR fits properly. Any ideas?

Greg

Click to expand...

You gould fiberglass the outside of the CR's.
Just my :2:

Eat said:

You gould fiberglass the outside of the CR's.
Just my :2:

Click to expand...

Thanks for that, as I was thinking the same thing.

I measured the circumference of the as-built CR's and they mic'd in at 4.693". That's a nominal CR OD of 1.494". The airframe ID is 1.520", so the delta between the CR OD and the airframe ID is 0.026" (0.7mm). I think I have some ~0.5 oz glass, so I figure perhaps a wrap or two will make up the difference.

Any thoughts on one wrap or two?

Greg

What did you do with the ones that came with the Kit? They are fiberglass & should hold shape after being cut.

Try using those, if they work...cut off the screwed up ones.

The WildChild is a very well made kit right out of the bag. Not sure why you are doing all the mods to it. Its your kit so you can do what you want with it but WHY?
The foam and glue method works very well and has flew with as big of a motor you can put in it. To each his own.
gp

blackjack2564 said:

What did you do with the ones that came with the Kit? They are fiberglass & should hold shape after being cut.

Try using those, if they work...cut off the screwed up ones.

Click to expand...

Oh. Well, my kit came with wood ones, not fiberglass. So I'm not sure what happened there.

If it came with fiberglass ones, rest assured I would have used them.

Greg

crossfire said:

The WildChild is a very well made kit right out of the bag. Not sure why you are doing all the mods to it. Its your kit so you can do what you want with it but WHY?
The foam and glue method works very well and has flew with as big of a motor you can put in it. To each his own.
gp

Click to expand...

I agree 100% with what you said, and is a great kit stock from the box.

But this is the Test Round, where I am trying new things with respect to my building skills.

Greg

On to fixing the CR's.

I cut a strip of 6oz fiberglass for each CR.



I tacked the the fiberlass with spots of rubber cement on the CR's, just enough to hold it in place.



I then mixed up some Aeropoxy laminating epoxy, then added milled fiber to strengthen the mix.



I performed the layup using a craft stick rather than a chip brush, since it seemed it would be a waste to use a chip brush on a job this small. I then carefully blotted the excess with a paper towel.

Afterwards, I added a layer of 0.5 glass to put more of a finished surface on the layup. I didn't need to any epoxy since there was enough epoxy to soak into this thinner layer. The layup was then set aside to dry.



Greg

Now on to the fin trailing edges.

This went just like the leading edges with respect to process.

I setup the masking tape then mixed the epoxy.



After applying the epoxy the carbon rod trailing edges, they were set aside to cure.



Greg

Success!

Today was the first good opportunity I've had to check the fit of the fiberglassed CR's inside the airframe. Was it going to be too loose and I would have to do the process over, or was it going to be too big and I would have to carefully sand it until it fit?

As it turned out, it fit like a glove. Not only that, it feels rock solid inside the airframe. It makes me think that once things are assembled, it will handle any motor that will fit.

So, the next step will be to create a removable CR for the aft end to hold the MMT's concentricity to the airframe. I already have extra CR's so that won't be a problem. Once I have made the removable CR ready, I will get things ready to epoxy the MMT to the airframe.

Greg

I'm back.

I had to take some time to help the youngest son with a scout project.



Greg

One thing I needed to have was an aft centering ring that would be temporary. I need it to just hold the aft end of the MMT in the proper orientation while the MMT is epoxied into the airframe. After the epoxy cures, I can remove it. That way I'll have access to the aft end to help with anchoring the fins.

Plan A: I took an extra CR that I had and wanted to drill a hole in it. I tried that but it didn't work so well. The CR was too thin and collapsed in half.

Plan B: Glue a dowel onto the CR and attach 2-56 screws into it. But I didn't have any dowels that size and I had my doubts that they would hold up well.

Plan C: Get a small bit of aluminum, then drill and tap it for 2-56 screws. There is not much metal to these, just enough to hold the screws.



After mixing the 5-minute epoxy, it was just a matter of positioning the screws on the CR.



Once it sets, I plan to clean off the excess and grind any excess aluminum off.

Greg

I made a little bit more progress today, as I was ready to attach the MMT to the airframe.

I used Aeropoxy 6209 for the adhesive mixed with some milled fiber. The challenge was how to apply epoxy to the mid CR. There is really not a good way to do this, as the epoxy is so thick that it is nearly impossible to get to flow. But the good thing is that the epoxy is so strong is that a little goes a long way.

I did use parchment paper as a masking medium to apply epoxy at the location of where the top CR would be.



I calculated that the MMT needed to be at 0.215" from the end of the airframe to accommodate the Aeropack retainer. I did some dry fitting to make sure that would work for both the AT and CTI reload cases. I then installed the temporary aft CR to hold the aft end of the MMT concentric with the airframe.



I finally set aside it to cure by taping the airframe to a handy bookcase.



Greg

On to the fins.



The first order was to remove the framing tape, used to center the rods on the fins. Afterwards, I added more tape to secure the ends, before removing the excess rod. Then I used a Dremel and a cut-off wheel to trim off the carbon rod.



The carbon trimming made quite a bit of dust, which bothered me a bit since that is nasty stuff and you do not want to get that in your lungs. So I donned a respirator and went back to work. Finally all the fins were trimmed up.



After trimming the rod, I cleaned up the surface of the fin by using 400 grit, and finishing by wet sanding (WD-40) with 600 grit. I wanted to see a uniform glare in the light. So I kept sanding until it looked right.



Greg

The airframe was then prepped for it's color.

I prepped it by wet sanded it with 600 grit, then used a concoction of denatured alcohol and other things to degrease the surface of the airframe. Since this is the Test Round, I didn't want to paint it. I wanted to use Trim MonoKote to cover it. The problem was that width of the standard Trim MonoKote sheet is about a mm too short. So it took two sheets. The first thing I did was take a 10mm section and put it in the area between the fins. I had the help of one of my children, by holding the airframe and a piece of angle aluminum as a reference. Then I placed the thin section of tape along the airframe and burnished it.

I then place the large section of MonoKote on a table (sticky side up, of course). I worked at getting the airframe at just the right spot, then rolled the airframe onto the Trim MonoKote. After rolling it on, I worked at getting the bigger air bubbles out. For the smaller air bubbles, I used the tip of a new hobby knife to "dot" the bubble and burnished it out.

I then trimmed away the slots with a new hobby knife.







So far, I liked the way that it turned out.

Greg

Fin action again.

One of the things I wanted to do is to was to put a few divots in the fin where it joins with the MMT. So I made some templates and glued it to the fin (temporarily), and made the cuts with a Dremel.



I wanted three different colors for the fins, to go with the "Test Round" motif. So it was time to add the Trim MonoKote.

The results were mixed, but in this case they will do. There were quite a few air bubbles that formed, and I haven't a clue as to why. The fins were thoroughly degreased, so I don't know if it was floating debris or what.

I did a dry fit test, so hopefully they will go on, soon. I just need to make a fin template so they are situated at the proper angle.



Greg

Well, it was time to make the fins part of the airframe.

First thing was to make the template. One of the things I should have done is allowed for fillets on the template. Lesson learned.



Then I needed to mask things off, to keep the airframe nice. Experience has shown me that if you don't want epoxy on it, it can find a way there.



Then I masked the fins as well. I mixed a batch of Aeropoxy 6029, then added milled fiber until it was the consistency of peanut butter. I used some 1/16" carbon rod to apply the epoxy onto the MMT, since there wasn't a lot of room. I added epoxy to the fin root, then slid them into the airframe slots. After all the fins were in place, I cut six pieces of the 1/16" carbon rod and glued them on each side of the fin root for additional strength.

Then I added the final piece, the aft centering ring. That is when things started going south. The ring would not fit. All this while the epoxy was beginning to kick. After about 10 minutes, I switched to Plan B and used a duplicate ring in its place. It was very frustrating, but there was nothing I could do but play the hand I was dealt.

Finally, I added the template. Hopefully, all the planning that I put in place will yield a good result. I'll know in a day or two.



Greg

I added a bit of graphics.





What do y'all think?

Greg

That is one of the coolest paint schemes I have ever seen. Not gonna lie.

Very Very Nice!!

Greg ,

You hit a homerun with the graphics ...big time ,love it ! :handshake:

Trim MonoKote I suspect ?

Paul T

MasonH said:

That is one of the coolest paint schemes I have ever seen. Not gonna lie.

Click to expand...

Coming from an Eagle Scout, I appreciate the comments.

T-Rex said:

Very Very Nice!!

Click to expand...

Thanks T-Rex.

sodmeister said:

Greg ,

You hit a homerun with the graphics ...big time ,love it ! :handshake:

Trim MonoKote I suspect ?

Paul T

Click to expand...

A humble "thank you", to you sir. And "yes", everything on the airframe and fins are Trim MonoKote. The nose cone is left as the natural color (HMWP, I think).

Greg

Time to add the Aero Pack.

The end was degreased to prepare if for the epoxy.



The area was masked off, because experience has shown me that epoxy likes to go where I don't want it to go.



I then mixed up a 2 gram batch of JB Weld, and applied it to the end of the MMT.



I then added the Aero Pack, and turned the airframe around to make sure that no stray epoxy got inside the MMT.



I then place some tape on the end to apply tension so that the retainer would be immobilized until the epoxy had set.



If the weather permits, I might launch Test Round on Saturday. So I wanted to make sure that the Aero Pack had plenty of time to cure before placing it on the pad.

Greg

Hmmm ... this is the interesting bit.

I'm starting of with 3/4" PVC.



I cut a length of about 2.5", then mark it in thirds along the longitudinal axis.



I then took an appropriately sized drill bit, and began to drill 6 holes.



There are 2 holes on each longitudinal mark.



More on this later.

Greg