MadCow 66mm Black Brandt II FG

[snrkl]

And another

 

[snrkl]

I have been trying to decide on a paint pattern for this that I like..

After trying all the actual BB variants, then "snrklified" blue/orange versions of them, I was still "meh..."

Then, I decided I need another superhero rocket..

I give you: "Frank's Castle"



or maybe "Para Bellum" is a better name...

 

[snrkl]

FG strips 5&6 applied.

 

[snrkl]

View attachment IMG_0447.jpg

A little bit of overhang on the left one at the retainer; I didn’t notice before the epoxy set up...

The hassle of using BSI Mid Cure: sets fast, but that means it sets fast...

 

[snrkl]

Sanded the fibre fillets down today. My amateur glassing technique meant there was some that probably weren’t wet down enough and ended up with some air bubbles that ended up sanding through.

 

[Wallace]

Luckily that's in a location that needs reinforcement least. Don't fret, carry on. And nice work btw...

 

[snrkl]

Luckily that's in a location that needs reinforcement least. Don't fret, carry on. And nice work btw...

That was my thinking, but I’m all about building the techniques. I’m enjoying the build...

 

[tim cubbedge]

A little Bondo spot putty will cover it right up. I'll be curious to know how well that reinforcement works. I have the 4" version and omitted the fiberglass cloth. Fillets cracked on landing on each flight.

 

[snrkl]

A little Bondo spot putty will cover it right up. I'll be curious to know how well that reinforcement works. I have the 4" version and omitted the fiberglass cloth. Fillets cracked on landing on each flight.

Well, I’ll be filleting with west 105/206/413 this weekend hopefully. I’m planning on laying some jumbo fillets (ie: bigger than a popsicle stick) to try to smooth this baby out some.

Once the West is laid, hard and sanded, I’ll likely overlay some smoother epoxy if the West with filler is rough looking.

 

[Tyler P]

Enjoying your build!

Before I got my LOC IRIS I thought I wanted an FG rocket. Glad I didn't go with one for my first higher-power machine. There are definitely some skills I want to learn before I tackle FG.

Threads like this are giving me a better idea of what I'm in for when I go that route, and giving me valuable info!

 

[Estesbasher]

(ie: bigger than a popsicle stick)

Get some of these spreader and cut them into the size and shape you want, round the edges so that when you pull the epoxy it comes out smooth.https://www.amazon.com/s/?ie=UTF8&k...qmt=b&hvbmt=bb&hvdev=c&ref=pd_sl_35h93ab3v3_b

 

[snrkl]

Get some of these spreader and cut them into the size and shape you want, round the edges so that when you pull the epoxy it comes out smooth.https://www.amazon.com/s/?ie=UTF8&k...qmt=b&hvbmt=bb&hvdev=c&ref=pd_sl_35h93ab3v3_b

I’ve got tongue depressors...

I’m REALLY trying to get some west system reusable mixing sticks, but they just don’t exist here in AU as a thing...

I can get them on eBay, but $8 for a five pack and $30 for shipping seems bananas.

 

[Estesbasher]

Go to the auto parts store. I'm sure they would have some bondo spreaders.
I'd take a good heavy pare of scissors and cut them into the shape you want.
Then I'd use 80-grit sand paper to round the edge, making it smoother with 220 and so on. With shipping cost like that you've got to look for things already local.

 

[snrkl]

Fillet 1 of six:

105/206/413 mix. Calculated I’d need about 12ml of epoxy. I love it when targets fit easily into mix ratios.

10g of 105
2g of 206
1.26g of 413

Gave me a wet toothpaste texture - better than the stiff frosting ratio I mixed when testing this system out.

Taped and laid: (put some dams in just in case


And tape removed:


I Peaked too soon and took the tape off too early. No biggie, just had more cleanup when I pulled the tips of the fillets when it started to gel.

I used a drink bottle top to pull the fillets; it ended up being JUST the right size to feather the fillet to the end of the fibreglass material.



Note for tomorrow’s fillets, the mix went tacky at about 50mins...

 

[snrkl]

With the formula and times figured out, second fillet worked a treat:

 

[snrkl]

New fillet is on the right hand side.

 

[snrkl]

Fillets 5 and 6 are done.

A whole lotta sanding starts tomorrow - the 413 filled fillets are not the glass smooth BSI ones I’m used to.

 

[snrkl]

Spent some time wet sanding today... while I like the 413 filled west for pulling the fillets, the finish sucks!



I also didn’t manage to get nice fillets into the fwd part of the fins like I’m used to. (I previously used BSI 15min and pulled the tool around the fwd end of the fin while the epoxy was toffee tacky...)

I pondered options and ended up just using 2g of fixit epoxy clay to form the fronts (and fill a few of the larger divots in the fillets)

I did two fin fronts tonight and I’ll do the other tomorrow after I see how these sand out.

While I was there I also filled the gaps left in the BT / TC that remained.



I’m off to get some sig microbaloons tomorrow. These are the closest I can get to 406 type micro beads.

 

[snrkl]

Forgot to add the pics of the fin fronts:

 

[snrkl]

This will give an idea of what the fin fronts looked like before the fixit clay. This was the LEAST messed up one of the three fins:

 

[snrkl]

Finished building up the last fillet front last weekend while my partner’s nephew was building his first rocket.

Finally got to it with a little sandpaper tonight.

The third one I did was blended EXCELLENTLY into the original fillet and required almost no sanding.




The others were ok:




but I REALLY figured out how to blend the fixit clay with isopropyl and the filleting tools on the last one. I wet the isopropyl down and worked the clay like it was wet earth clay, really pushing the clay smooth and blending it.

 

[snrkl]

The next goal is to fill and sand smooth the small divots left from the 413 filled epoxy from the first fillets.

I think next time I’ll leave the fillets proud until the epoxy is toffee tacky then pull the fillets with a very isopropyl wet tool (acetone would have melted the fillet tool) but for now, I need to fill and sand them.

Plan is to use SIG microbaloon filled epoxy, so I’m doing a test now:

“In the absence of West System 406 filler here in Australia, and given my dislike for the 413 microfibre for sanding smoothness, tonight I started experimenting with SIG microbaloons...



105/206/SIG Microbaloons mixed to a stiff cake icing (frosting) consistency then laid in a test butt joint.

No fillet pulling here, as the main goal is to test both strength and sand-ability.

“

The goal is to see how easily sanded it is once cured; hopefully I’ll be able to sand it down nicely with a tube wrapped in sandpaper.

 

[Tyler P]

Spent some time wet sanding today... while I like the 413 filled west for pulling the fillets, the finish sucks!

View attachment 366273

I also didn’t manage to get nice fillets into the fwd part of the fins like I’m used to. (I previously used BSI 15min and pulled the tool around the fwd end of the fin while the epoxy was toffee tacky...)

I pondered options and ended up just using 2g of fixit epoxy clay to form the fronts (and fill a few of the larger divots in the fillets)

I did two fin fronts tonight and I’ll do the other tomorrow after I see how these sand out.

While I was there I also filled the gaps left in the BT / TC that remained.

View attachment 366274

I’m off to get some sig microbaloons tomorrow. These are the closest I can get to 406 type micro beads.

View attachment 366275

I used Sig Micro Balloons on my IRIS and I found they worked great. Also really nice to sand.

 

[blackjack2564]

Be aware that micro ballots can substantially weaken fillets, depending on how much used.

No problem with sport fliers, but when building extreme projects flying upper mach regimes...1.5 & above or with large fin projects you risk cracked fillets.
406 actually used to strengthen epoxy for attaching cleats & various hardware to boat hulls.
You probably have fiberglass chopped fiber fillers or "pulp" or strands. Use those where strength is needed & ballon where just cosmetic.

That being said your fillets look vey nice...keep it up.

 

[Brian Kirksey]

Great thread. Thank you for sharing.

 

[snrkl]

Be aware that micro ballots can substantially weaken fillets, depending on how much used.

No problem with sport fliers, but when building extreme projects flying upper mach regimes...1.5 & above or with large fin projects you risk cracked fillets.
406 actually used to strengthen epoxy for attaching cleats & various hardware to boat hulls.
You probably have fiberglass chopped fiber fillers or "pulp" or strands. Use those where strength is needed & ballon where just cosmetic.

That being said your fillets look vey nice...keep it up.

Understood on the strength - the microbaloons are being used over:
Layer 1: single layer of glass cloth
Layer 2: large fillet of 105/206/413 mix
Layer 3: 105/206/microbaloons only for sandability and finish on the surface. I estimate 98% of the microbaloon filled epoxy will be sanded off.

 

[blackjack2564]

Ok, I get it. You are making your own version of finish/filler!

Good on you.

 

[BDB]

This rocket, with those fillets and the boat tail, is going to be beautiful!

 

[snrkl]

This rocket, with those fillets and the boat tail, is going to be beautiful!

That’s the plan, Stan!! [emoji12]

 

[snrkl]

Sanded a fillet in the test strip (80 then 240 grit)



The air bubbles are annoying the daylights out of me.

So the test now to see if the high build filler primer can handle them.

One very wet coat of super cheap auto filler primer.



I love this stuff... even on a heavy coat I can be sanding after 20mins. It’s incredible.

I think it might take several coats and sanding it all off between coats. Let’s see how we do...