Madcow Mini fiberglass series

I was thinking two or three, small countersunk screws at the base of the nose cone into the coupler would work well and look better than button-head or plastic rivets. The plastic rivets the kit comes with to hold the payload tube are already on the big side for this size rocket and I wish I had used countersunk screws there as well. The other option I'm considering is seeing if I can find two or three threaded rods and attaching them to the inside of the coupler, then sliding the bulkhead on and securing with nuts and washers. That should result in a lot more gluing area than attaching a ring, like I did with my Punisher.

While waiting for the retainer for the Frenzy to arrive, I decided to pull out the Mini BBII. This is set up for motor deploy, and is shorter and understandably lighter than the Frenzy. The bag and contents weigh 15.8 ounces. I upgraded to the FWFG nose cone, which has a solid tip (phenolic maybe?). No boat tail on this kit, sadly. Would be tough to make work with the 29mm motor mount.

Also building a Mini Frenzy D/D. Taped off for fin fillets over turkey day holiday weekend. I'm using one of the orange printed AV sleds from Wildman. Need to take AV bay to hobby shop to pick out a li-po that will fit. Stickershock has decals available. Planning to build a launch tower soon. The mini Frenzy will fly along side my mini Intimidator from Wildman. And actually they are so similar in size and weight, both should be fun.

See ya,
Rod

RodRocket said:

Also building a Mini Frenzy D/D. Taped off for fin fillets over turkey day holiday weekend. I'm using one of the orange printed AV sleds from Wildman. Need to take AV bay to hobby shop to pick out a li-po that will fit. Stickershock has decals available. Planning to build a launch tower soon. The mini Frenzy will fly along side my mini Intimidator from Wildman. And actually they are so similar in size and weight, both should be fun.

See ya,
Rod

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Rod,

No promises about the overall quality but I recently bought these 2S Lipos and charger to power the Eggtimer Quantum and Eggfinder in my 1.6" DX3. The fit looks good and I was really happy with the cost.

https://www.amazon.com/gp/product/B01J92V71A/?tag=skimlinks_replacement-20

What epoxy are you using in these builds?

RodRocket said:

Also building a Mini Frenzy D/D. Taped off for fin fillets over turkey day holiday weekend. I'm using one of the orange printed AV sleds from Wildman. Need to take AV bay to hobby shop to pick out a li-po that will fit. Stickershock has decals available. Planning to build a launch tower soon. The mini Frenzy will fly along side my mini Intimidator from Wildman. And actually they are so similar in size and weight, both should be fun.

See ya,
Rod

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My preferred charger https://www.amazon.com/dp/B005LH3392/?tag=skimlinks_replacement-20
I can't say enough good things about the HiTec charger as its been perfect, easy to use and reliable.
And my batteries are from Hobbyking mostly 180mah and 300mah Turnigy Nano-Tech 2S batteries with JST connectors for output and JST-XH balance connectors.

I'm using Bob Smith 15-minute for construction and 30-minute for fillets.

This thread has definitely encouraged me to think about stepping back a little after GD38 L2 build.
Especially after seeing madcow has a GD29!
Thank you muchly

I'm watching this one intently. How does the eggfinder/lipo/nosecone configuration affect the weight and balance? Doing anything toward the rear to compensate? Anything that's removable so if you don't fly the transmitter, you can fly on lesser motors safely? Be great if we had a Pnut sized Eggfinder for these little rockets!

kcobbva said:

I'm watching this one intently. How does the eggfinder/lipo/nosecone configuration affect the weight and balance? Doing anything toward the rear to compensate? Anything that's removable so if you don't fly the transmitter, you can fly on lesser motors safely? Be great if we had a Pnut sized Eggfinder for these little rockets!

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It would, wouldn't it? :wink:

cerving said:

It would, wouldn't it? :wink:

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Yes Sir. Although I might need 8.0 glasses to see the parts for that!!!!!!!!!!!

From my OR sim loaded with a I200 and a mass object to represent an Eggfinder TRS in the nose (I use mine a lot for tracking only) my calibers of stability went from 3.6ish to 5.2ish. even loaded with a I200 this rocket should be stable, the only thing I have not accounted for in the sim is weight of paint and epoxy.

I can tell you from experience that it's virtually impossible to make a 38mm rocket of this length unstable, unless you remove the fins. I have several of them, on both 29mm and 38mm motors.

Flyfalcons said:

Just about to pull the tape from the last set of fillets. I've had success with Bob Smith 30-minute epoxy, so that's what I'm using here.

So far the motors I'm planning are F-H using my 40-120 and 180 cases. I might add a 240 case to my arsenal some time as well. I have an Eggfinder I need to build, and if I don't destroy it in the process then I might think about going bigger. An I205 will send this well over a mile.

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Is the tape used to make a straight line on the fillets? Does the edge of the tape get stuck under the glue?
Ive been using wood glue for my fillets, should I try epoxy?

The tape keeps a clean surface after applying the epoxy and creating nice fillets, the peeling away creates nice edges. Ensure you don't have a big edge but a smooth one on the tape when you peel it off.

On a fiberglass kit like this, yes definitely Epoxy for obvious reasons. On a wood kit, I generally use wood glue on low power rockets and epoxy on mid/high power. When using epoxy, which doesn't shrink like wood glue does, I make tape edges like those seen in the photo. I'll mix up the 30-minute epoxy and carefully pour it along the fillet line. When the epoxy starts getting to the leather stage, I will use something with an appropriate radius (end of a popsicle stick in this case), and pull the fillets to give a rounded shape. After that, I pull the tape off. This allows the epoxy, still in its leather stage, to even out at the edges. On this build, the fillet edges turned out so well that I don't need to do any further sanding or smoothing on them.

Ok, so pull the tape off before its dry. May I ask to what you are using to pour it? I have 15min epoxy that I mix together using a toothpick. Then I apply where needed with the toothpick.

ascastil said:

Ok, so pull the tape off before its dry. May I ask to what you are using to pour it? I have 15min epoxy that I mix together using a toothpick. Then I apply where needed with the toothpick.

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I only use rocketpoxy now. Have retired Bob Smith, but it works. I would almost recommend using 30 min to give yourself work time, then time to make a fillet, then peel the tape before it hardens. 15 min may be too fast for all of that. I drip all mine on with a stir stick and then begin making the fillet with the previously mentioned popsicle stick held at different angles on each stroke to only remove a little at a time, ending up with a nice smooth fillet only as large as needed.

Just a small mixing cup that I squeeze the top to make an improvised spout. Just pour out a little bit along the fillet line and even it out with the popsicle stick. 30-minute evens out much better than 15-minute. I even like to hold the cup of mixed epoxy in front of my heat lamp to make the epoxy more viscous before pouring.

Flyfalcons said:

Just a small mixing cup that I squeeze the top to make an improvised spout. Just pour out a little bit along the fillet line and even it out with the popsicle stick. 30-minute evens out much better than 15-minute. I even like to hold the cup of mixed epoxy in front of my heat lamp to make the epoxy more viscous before pouring.

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Btw. Enjoying your thread. Bought the Non-FG version for my 9 year old for Christmas, and this same one for me for Christmas. We'll have some fun building together! Watching how things go for you and picking up good tips! Also see Enumclaw in your location. Love that area! Lived in Issaquah briefly before joining the military. Really miss it out there!

Thanks, I've been completely swamped with my work schedule and getting ready for the holidays that I have not been getting nearly as much garage time in as I'd like. The little Frenzy's airframe is nearly complete so it's just a matter of paint and wiring the avbay (RRC2+ altimeter on the way, Lipo battery planned). I'm sure you and your son will have a blast with these little Frenzies; I'm also looking forward to my mini BBII and cardboard mini Pike.

Same here, nice build. Just getting back in the hobby and trying to soak up some techniques. So much more info on this forum than American Spacemodeling, even though I did learn a lot from there.

Edit. I actually should concentrate on getting a parachute to deploy rather than fillets, lol.

I use rocketpoxy for everything. And j-b weld for motor retainer.

I found a couple short pieces of nylon rod that makes a great fillet tool. Using a black sharpie I color the edge of the rod, then pull the rod along the fin and body tube. The sharpie rubs off and leaves nice tape lines. Tape off to keep fillet edge clean and keep mess to a minimum.

I do a pair of fillets at a time, then when those cure, rotate and repeat. I start with something small to get rocketpoxy down into edge with minimal bubbles then add more as needed. Use rod to pull across and smooth out rocketpoxy. I have rag handy to whipe any extra off rod and off rocket.

Fillets look amazing when done. Minimal sanding to feather tape edge.

RodRocket said:

Using a black sharpie I color the edge of the rod, then pull the rod along the fin and body tube. The sharpie rubs off and leaves nice tape lines.

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Ah. Never thought of doing that! Slick idea!

dford said:

can we get some more photos please when you are available?

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Yes, absolutely. I'm on a trip through Saturday but was thinking of a short tutorial on my fillet techniques using the Mini BBII.

I have the retainer on the Frenzy, and there is a slight issue. With a 40-120 case installed, the retainer cap will actually tighten onto the bottom of the body tube before it tightens onto the motor case. I'd say the case has about 1/8" of play fore and aft. I'll probably have to make a thin tape ring to stand the motor aft slightly to prevent play in flight.

I discovered the body tube is a perfect size to stuff into a paper towel roll to stabilize it while the fins are positioned and the epoxy cures.

I knew the BBII would be a bit shorter than the Frenzy, but I was surprised to see it's not as short as I thought it would be. Since this design doesn't have a boat tail, I think it would be cool if Madcow were to tweak the fin design a little, sell it with a longer dual-deploy setup body tube, and call it a BBIII. Hmm, maybe I'll call Mike and see if he could do that for me.

Flyfalcons said:

I have the retainer on the Frenzy, and there is a slight issue. With a 40-120 case installed, the retainer cap will actually tighten onto the bottom of the body tube before it tightens onto the motor case. I'd say the case has about 1/8" of play fore and aft. I'll probably have to make a thin tape ring to stand the motor aft slightly to prevent play in flight.

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Thanks for the heads-up on this, I will need to add a bit more mmt behind the rear CR than the instructions show for my Mini-Frenzy DD. I managed to get as far as washing the parts today.

The BBII kit does not come with an eyebolt to attach the shock cord. The instructions would have you tie a bunch of knots in the shock cord and glue the knotted side on the top side of the nose cone bulkplate. In the interest of being able to change out the cord if needed, I drilled a second 1/4" hole in the bulkplate so I can loop a piece of kevlar through the holes and attach the shock cord to that. I used a deburring tool to bevel the holes and prevent stress cuts on the kevlar loop.