Venturing into mid-power!

[Vethen]

My package from Estes just arrived! inside is the pro series II scion and some epoxy.

i have never used this stuff and it looks very liquidy. I cannot imagine how something so thin can be molded into fillets. Do you let it cure for a few minutes before applying it or do you apply it right away?

as the build begins I'll post the progress and pictures.

 

[noffie79]

Just mix the two together in equal amounts. I use a Popsicle stick to stir them for a minute, then scoop some up and lay it into the joint. Then use either the stick or a gloved finger to smooth it out. Let it sit for a few hours, because it'll run, before turning and doing your next fillets.

 

[Vethen]

I remember someone on here once mentioning how they'd lay their epoxy out as a thin sheet to let it cure before shaping it in order to get clean fillets.

Also, it seems a shame to have a BT that's exactly two pieces and not try to turn it into a zipperless design. Anyone try installing a bulkhead on the bottom of the upper BT, or would the bulkhead be better on the bottom of the upper BT segment?

 

[rharshberger]

Most of us add some cabosil or phenolic microballons to thicken the epoxy.

 

[noffie79]

I let my RocketPoxy sit a bit to get some air bubbles out. But if you're just using the Bob Smith variety of epoxy, I don't think there's a need to let it sit, especially if it has a short work time.

 

[Vethen]

I have a the 30min epoxy off of Estes' site, by the way.

 

[McKailas Dad]

I've only used Proline 4100 epoxy. What I have found is the ambient room temperature has a lot to do with the cure times. I found the Proline to be relatively thin as well, and usually wait 10-15 minutes after mixing to start working with it. I go for the 'two-drip' test, when the second drip hangs there for a second before dropping..

Depending what I'm doing, I'll even let it sit for longer than 15-20 minutes, like when I'm epoxying in a piece of Kevlar to a nosecone. Not quite bubble gum consistency, but obviously thicker than what I would use for centering rings, etc.

Heating it will make it cure faster, and keeping it cool will make your working time longer, at least in my humble experience. I've built 5 FG rockets with it, and have had no 'failures' so...it must be working lol

 

[Vethen]

Thank you for the wonderful starting information! I'll wait till tomorrow to try out epoxy for the first time. Would you use it to tack the fins, or CA for tacking and epoxy for the fillets?

 

[noffie79]

For fins, if you're doing epoxy fillets, you can tack them in place with CA. I usually do a thin bead of wood glue along the fin root that will meet the MMT, let it dry, then do my fillets

 

[Vethen]

I prefer wood glue for the fin/mmt tacking so I'm glad to hear you say you do that. I suppose I just need to figure out my approach for the BT, glue it into one piece as the instructions say, or get fancy with a lower separation joint.

 

[rharshberger]

I prefer wood glue for the fin/mmt tacking so I'm glad to hear you say you do that. I suppose I just need to figure out my approach for the BT, glue it into one piece as the instructions say, or get fancy with a lower separation joint.

Vethen, there have been L3 rockets built with nothing more than wood glue and wood and cardboard. To often we get hung up on epoxies as a necessity. Simple Titebond I,II,III will be fine for assembly of a cardboard and wood MPR, Titebond Trim and Moulding glue (aka TMTG, No Run No Drip, or a new name I can't recall) is excellent for making external fillets, it just takes a couple of passes where epoxy can do it in one. Epoxy adds weight when it may be unnecessary, the exception is motor retainers, which need to be JB Weld or some high temp epoxy. My $.02

 

[scsager]

My package from Estes just arrived! inside is the pro series II scion and some epoxy....

The Scion can be built entirely with wood glue. The only exception is to use epoxy on the motor retainer.

 

[Vethen]

I suppose I should mention that the use of epoxy is for experience with it, and I have no intention of leaving behind my beloved loctite. Never used the stuff before so I decided it was time to try it out!

 

[rharshberger]

I suppose I should mention that the use of epoxy is for experience with it, and I have no intention of leaving behind my beloved loctite. Never used the stuff before so I decided it was time to try it out!

That's as good of reason as any, practice.

 

[WLViking]

I suppose I should mention that the use of epoxy is for experience with it, and I have no intention of leaving behind my beloved loctite. Never used the stuff before so I decided it was time to try it out!

I did the same thing. Built a Ventris, and a Partizon with Epoxy for practice. Also built an Argent with just wood glue. All work on L1 motors just fine. But learning the epoxy techniques on these kits has made me feel a lot more confident for the HPR I am building.

Also, working on my scion, except, I got the short 4 fin body tube and another coupler to make an extended Leviathan instead. Did all the internal fillets tonight. Good Luck!

 

[Vethen]

I did the same thing. Built a Ventris, and a Partizon with Epoxy for practice. Also built an Argent with just wood glue. All work on L1 motors just fine. But learning the epoxy techniques on these kits has made me feel a lot more confident for the HPR I am building.

Also, working on my scion, except, I got the short 4 fin body tube and another coupler to make an extended Leviathan instead. Did all the internal fillets tonight. Good Luck!

Considering that the epoxy will push the CoG further aft, I've been toying with the idea of installing all 4 fins. And possibly their direction..

 

[423yjl]

tip:

have alcohol cleansing pads, to help clean up

 

[WLViking]

Considering that the epoxy will push the CoG further aft, I've been toying with the idea of installing all 4 fins. And possibly their direction..

Haha, and then you have an Extended Leviathan! All you would need is this: https://www.estesrockets.com/rockets/pro-series/parts/031751-pro-series-ii-slotted-body-tube and another coupler and you have what I am building. That will add another 10" to the rocket and help with some of the weight / Stability issues. I am coming out at 2+ Cal stability because of the extra length.

Now, please keep in mind, you are making a big trade off here. By overbuilding, you are limiting yourself essentially to G+ motors. F motors MAY work on a low wind day, but I would not even chance it. Your velocity off of the rod (I simmed using a Mantis 57", although this will only ever be launched at club launches on a rail) is sub 50 ft/s prior to getting into G motors. The nice thing is that on Gs you will have a nice low apogee and be able to watch the whole flight with a relatively easy recovery.

For me, the trade was fine, because I going to be launching this primarily on high thrust Gs and H motors, and just use it to get experience prior to L2. Like you, I built the others to practice L1 techniques. The beauty of these overbuilt test kits is that I was at a launch and just decided to get my L1 cert. My Ventris and Partizon both flew that day on H motors because they could handly the stress easily and the Partizon was built mostly with wood glue. I'm newer, so take all of this with a grain of salt, but happy to talk you through anything or share my ORK file.

 

[WLViking]

tip:

have alcohol cleansing pads, to help clean up

This is 100% necessary. You WILL screw up and you WILL spill. Alcohol will clean any mistakes. I recommend Getting the liter bottle though and using women's makeup removal pads or paper towels. More work, but a lot cheaper and you can wash your GLOVED hands prior to removing the gloves. Plus, at 91% concentrate, it is a lot stronger.

Speaking of gloves, wear at least nitrile gloves prior to even taking the epoxy out. Check the MSDS to see if nitrile will be ok. (For some brands it is not) And I always wear a mask, eyewear, and apply it in my garage.

Venturing up to this territory, PPE is extremely important. It is a big step up from Wood Glue.

 

[ActingLikeAKid]

When I built my Argent, I used epoxy for gluing in the fins, then I laid down a bead of epoxy as a "pre fillet", then I used this stuff:
https://www.jbweld.com/products/kwikwood-epoxy-putty-1oz
for the fillets. It was probably overkill and added weight, but the fillets look gorgeous. And the kit's estimated weight is 467g, but I came in at 450, so .... not that much weight
Basically I rolled out a thin snake of putty (like 1/8" dia) and squished it into the joint, then carefully smoothed it and blended it. It's nice because it adds some strength, it looks good, and covers any missteps you made when you were doing the epoxy fillets.

 

[Vethen]

Venturing up to this territory, PPE is extremely important. It is a big step up from Wood Glue.

PPE you say? Looks like all those high level chemistry classes will pay off! I have quite a stock of protection glasses, splash proof goggles, and flame resistant lab coats with snap closed cuffs.


Low altitude flights are perfectly fine with me at this point. I'm not yet even considering attempting my L1, just want to build a few rockets and get comfortable with all the materials. I'll sim my build with heavier fillets and a few different positions of the fins. See what turns out best, and if any nose weight would help.

 

[Vethen]

So after thinking I was going to use a Kevlar shock cord loop, I'm leaning more towards adding a baffle and using a bulkhead to separate the rocket in the middle instead of at the NC..

Here is my initial thoughts;

Mount the baffle in the bottom tube, just far enough back for the coupler to fit.
Add a bulkhead about midpoint in the upper tube, leaving enough room for the laundry to loosely fit.
Attach the NC with some pins, leaving a space up top to use as a make-shift payload area for future use. (tape for friction fitting maybe instead but pins look official!)

 

[WLViking]

So after thinking I was going to use a Kevlar shock cord loop, I'm leaning more towards adding a baffle and using a bulkhead to separate the rocket in the middle instead of at the NC..

Here is my initial thoughts;

Mount the baffle in the bottom tube, just far enough back for the coupler to fit.
Add a bulkhead about midpoint in the upper tube, leaving enough room for the laundry to loosely fit.
Attach the NC with some pins, leaving a space up top to use as a make-shift payload area for future use. (tape for friction fitting maybe instead but pins look official!)

View attachment 281325

I am doing something similar but in a different way. Keeping the elastic putting in an inch of extra coupler I have at the 20 1/2" mark and then building a baffle resting on top at the 21 1/2" mark. Doing 4 half moons of from wooden hobby discs that will take it to the 23 1/2" mark. Mount will be an eyelet bolted in.

That gives me 6" of 3" space for the shock cord and chute. Keep in mind, I have the extra 10" on the bottom from picking up the leviathan fin BT piece.

 

[WLViking]

Pic for visual reference.

 

[Vethen]

Pic for visual reference.

Picture helped a lot! This looks very effective. Is there a best location for the extended eyelet, bottom or top section? I feel like the extended part is most effective on the bottom section, since the NC will be pulled in the opposite direction.

 

[WLViking]

Picture helped a lot! This looks very effective. Is there a best location for the extended eyelet, bottom or top section? I feel like the extended part is most effective on the bottom section, since the NC will be pulled in the opposite direction.

I'll send you the open rocket when I get in front of my computer tomorrow. It will show where everything is laid out. The colors are not how it will look but functionally it is all there.

 

[Vethen]

I'll send you the open rocket when I get in front of my computer tomorrow. It will show where everything is laid out. The colors are not how it will look but functionally it is all there.

I'll be looking forward to it! I hope to order my parts tomorrow so I can speed up my process