Haha! Thanks but I want to see it with all the fins in place and maybe then I'll call it.I do believe that constitutes "proof of concept"! Congratulations!
Dragon Rocketry 4" Exocet MM38 Unboxing & (Eventual) Build
- Thread starter KenECoyote
- Start date
Help Support The Rocketry Forum:
I passed out last night, but I'm good today. I originally thought I might be coming down with something since my daughter was getting over some cold and we were hanging out all day yesterday... shopping... at the mall... where many seemed sick... and I also watched the new Avatar movie with her.
Last edited:
Back at it!
Ok, I used 5 min epoxy for the fin opposite the first one I had glued in and I used my jig again with the rod extended through to ensure alignment across the span.
Then I used 15 min epoxy for the opposing mid fin. 15 minutes was better because 5 min didn't seem to be enough for such a long fin and to also work at aligning.
Using the jig again, you can see how things align up from the front view.
Ok, I used 5 min epoxy for the fin opposite the first one I had glued in and I used my jig again with the rod extended through to ensure alignment across the span.
Then I used 15 min epoxy for the opposing mid fin. 15 minutes was better because 5 min didn't seem to be enough for such a long fin and to also work at aligning.
Using the jig again, you can see how things align up from the front view.
I think it's aligned pretty darn good...
I got the flying fish's fins in last night and will be installing rail buttons (should've probably been done sooner, but I had my reason...more on that later) and doing fillets.
For now, here's a mock assembly to see it's size compared to Madcow's 4" Phoenix and Patriot rockets.
My neighbors may be starting to worry...
For now, here's a mock assembly to see it's size compared to Madcow's 4" Phoenix and Patriot rockets.
My neighbors may be starting to worry...
I've been held up on my Exocet build by plans to bevel the fins, but I don't have a good way to do that. Do you have plans to bevel your fins?
Originally I was going to, but I decided not to figuring that's the standard build. If it bothers me, I'll bevel them later even if it's much harder once mounted.
For bevelling, a router table makes the most sense. I have the Dremel one which is great on smaller builds, but slow on 1/4" plywood fins and it struggles. I have a standard size router table I haven't used yet, but plan to later and I even got a router bit for it.
Belly button!
So at this point it made sense for me to install the middle rail button. This is because I am going to have it mounted into the middle CR (there are three!). I always prefer to mount a rail button to a CR if possible since that's the strongest in my opinion.
Usually the forward CR is too far forward, but in this case the middle CR is nicely placed. I used a ruler to measure where the middle CR was and then added 1/8" so that it'd be in the middle of that CR (measure several times and take your time since you don't want it to be off).
Then I drilled a pilot hole, followed by larger drill bits, each time ensuring that I wasn't drilling through to the side of the CR by peeking through the open aft end.
BTW - On a hunch, I thought the Estes Tube marker may serve as a perpendicular drill guide and wouldn't you know...it does! You just need long enough drill bits.
The final/largest drill bit should be smaller than the screw, but large enough so you can start the screw into the hole.
Unless I mixed up rail buttons, this kit came with 3/32 hex head bolts.
So at this point it made sense for me to install the middle rail button. This is because I am going to have it mounted into the middle CR (there are three!). I always prefer to mount a rail button to a CR if possible since that's the strongest in my opinion.
Usually the forward CR is too far forward, but in this case the middle CR is nicely placed. I used a ruler to measure where the middle CR was and then added 1/8" so that it'd be in the middle of that CR (measure several times and take your time since you don't want it to be off).
Then I drilled a pilot hole, followed by larger drill bits, each time ensuring that I wasn't drilling through to the side of the CR by peeking through the open aft end.
BTW - On a hunch, I thought the Estes Tube marker may serve as a perpendicular drill guide and wouldn't you know...it does! You just need long enough drill bits.
The final/largest drill bit should be smaller than the screw, but large enough so you can start the screw into the hole.
Unless I mixed up rail buttons, this kit came with 3/32 hex head bolts.
Here's a check from the aft end that the bolt didn't come through the side of the CR. The darker area you see is actually glue and the CR looks great.
Once I was happy with the rail button install, I removed it and put it back into the bag so I wouldn't lose it. I then trimmed and covered the hole with a bit of the trimmings and applied a smudge of wood glue so paint wouldn't get into the hole.
Once I was happy with the rail button install, I removed it and put it back into the bag so I wouldn't lose it. I then trimmed and covered the hole with a bit of the trimmings and applied a smudge of wood glue so paint wouldn't get into the hole.
Remember to screw it!
Next I drilled pilot holes and added two screws to the aft CR ring.
This is so I can temporarily install the CR snug into the Aft, apply my outer fillets and then remove the ring to do internal fillets.
The reason for this order is that if I applied internal fillets first, the outer bt may become slightly off and then the CR may not fit in (I learned from a past instance of this).
So next will be outer fillets. I'm quite busy with work (due to a shortened work week, yet deliverables still need to go out) as well as holiday stuff, so I'm not sure when I'll get to it, but likely by next week if not sooner.
Happy Holidays! 
Next I drilled pilot holes and added two screws to the aft CR ring.
This is so I can temporarily install the CR snug into the Aft, apply my outer fillets and then remove the ring to do internal fillets.
The reason for this order is that if I applied internal fillets first, the outer bt may become slightly off and then the CR may not fit in (I learned from a past instance of this).
So next will be outer fillets. I'm quite busy with work (due to a shortened work week, yet deliverables still need to go out) as well as holiday stuff, so I'm not sure when I'll get to it, but likely by next week if not sooner.
Happy Holidays!
Fillets, fillets, fillllllllllets!
In preparation for epoxy fillets, I used carbon paper and a fondant tool (ball ended) to mark for fillets.
I then used LOT of blue tape along those lines. I also folded over each tape edge for easier removal later.
Marked center lines also help to make sure the angled edges are even if they intersect at that line.
Lots of tape!
That masking tape dispenser is a very handy tool for a job such as this and I got it for $21 for two on Amazon.
In preparation for epoxy fillets, I used carbon paper and a fondant tool (ball ended) to mark for fillets.
I then used LOT of blue tape along those lines. I also folded over each tape edge for easier removal later.
Marked center lines also help to make sure the angled edges are even if they intersect at that line.
Lots of tape!
That masking tape dispenser is a very handy tool for a job such as this and I got it for $21 for two on Amazon.
Last edited:
In the thick of things.
I used Rocketpoxy, which is very thick like peanut butter; however, it allows you to do a bunch of fillets at one time since it can hang sideways or upside down fine after applying.
Since it's so thick, it can be tricky to measure out equal parts, so I weighed after each part using my digital gram scale and mixed.
Edit: 2 posts down I provide better pointers for using Rocketpoxy for these fillets.
I first applied to the back/ rail button side in case I screw up, then it's less visible.
I used the bigger ball for slightly larger fillets on the back fins since they are exposed to higher landing stresses than the mid fins.
I used Rocketpoxy, which is very thick like peanut butter; however, it allows you to do a bunch of fillets at one time since it can hang sideways or upside down fine after applying.
Since it's so thick, it can be tricky to measure out equal parts, so I weighed after each part using my digital gram scale and mixed.
Edit: 2 posts down I provide better pointers for using Rocketpoxy for these fillets.
I first applied to the back/ rail button side in case I screw up, then it's less visible.
I used the bigger ball for slightly larger fillets on the back fins since they are exposed to higher landing stresses than the mid fins.
Last edited:
I was able to do half of the rocket before the epoxy started getting firmer and also running out of my mixed epoxy batch.
If this was a normal rocket with just the rear fins, I could've finished all of it, but there is a lot here and it seems better to break it up into two sessions.
I started to peel the tape before the epoxy set.
I think it came out very nicely!
The other side had a few small bubble bulges (as the epoxy got firmer it wasn't laying down as smoothly), but it's minor and can be sanded and filled.
Til next time!
If this was a normal rocket with just the rear fins, I could've finished all of it, but there is a lot here and it seems better to break it up into two sessions.
I started to peel the tape before the epoxy set.
I think it came out very nicely!
The other side had a few small bubble bulges (as the epoxy got firmer it wasn't laying down as smoothly), but it's minor and can be sanded and filled.
Til next time!
My better half?
Today I continued work on the fillets on the rest of the rocket.
Here are the items I used:
This time I used a small ketchup cup I grabbed from Burger King a while back (ok... I stole a bunch lol). It was just the right amount of epoxy for half the rocket! It ended up being 20 grams of each part for a total of 40g up near the brim.
The popsicle size craft sticks were just the right size and shape to mix, apply, smooth and scrape up excess epoxy off the sides of the taped area.
The fondant tools were off Amazon ($8 for a set of 4) and were for final shaping.
The alcohol was for cleaning off the tools as well as final smoothing of the fillets (provides a slick non-grip surface for the tool to glide and smooth out the fillets).
Finally gloves because (aside from keeping your hands clean) you may eventually develop an allergic reaction to epoxy after repeated exposure and I hear it's quite unpleasant.
Today I continued work on the fillets on the rest of the rocket.
Side bar: I don't know about the rest of you, but sometimes I view some of the parts of rocket building (ex. sanding, filling spirals, fillets) as a chore and kinda put them off. However, I'll eventually roll up my sleeves, see it as a challenge and just get it done. The end results are always well worth the effort imo.
Here are the items I used:
This time I used a small ketchup cup I grabbed from Burger King a while back (ok... I stole a bunch lol). It was just the right amount of epoxy for half the rocket! It ended up being 20 grams of each part for a total of 40g up near the brim.
The popsicle size craft sticks were just the right size and shape to mix, apply, smooth and scrape up excess epoxy off the sides of the taped area.
The fondant tools were off Amazon ($8 for a set of 4) and were for final shaping.
The alcohol was for cleaning off the tools as well as final smoothing of the fillets (provides a slick non-grip surface for the tool to glide and smooth out the fillets).
Finally gloves because (aside from keeping your hands clean) you may eventually develop an allergic reaction to epoxy after repeated exposure and I hear it's quite unpleasant.
Last edited:
Here are the rest of the fillets setting. I'll remove the tape in about an hour or so (wait too long and the epoxy may harden too much and make it difficult to peel off the tape).
Fillet finale!
Here's a pic of one of the fillets after tape removal.
The other side wasn't as good since the Rocketpoxy got thicker and I didn't press it hard enough against the tape, but nothing a bit of sanding won't fix.
Here's a pic of one of the fillets after tape removal.
The other side wasn't as good since the Rocketpoxy got thicker and I didn't press it hard enough against the tape, but nothing a bit of sanding won't fix.
Inside job.
Now that the outer fillets are done, can't forget the rear internal fillets.
I used Rocketpoxy again so that I could do more of them each batch and was able to do it all in two batches.
It was tricky getting the thick goopy epoxy in there and spread, but the popsicle size sticks were used again and I found that applying a goop at the middle and then spreading worked best. I then used a chopstick dipped in alcohol to smooth the fillet.
Now that the outer fillets are done, can't forget the rear internal fillets.
I used Rocketpoxy again so that I could do more of them each batch and was able to do it all in two batches.
It was tricky getting the thick goopy epoxy in there and spread, but the popsicle size sticks were used again and I found that applying a goop at the middle and then spreading worked best. I then used a chopstick dipped in alcohol to smooth the fillet.
Popsicle Trivia:
So if it weren't for Epperson's kids, I'd be calling them "Eppisicle sticks".
Back at it!
I've continued to build this fish, but have a number of other projects I'm juggling, so I've waited for a few steps to be done to update.
I epoxied on the rear CR with a stout fillet and then used JB Weld to attach a Aeropack 54mm retainer.
I've continued to build this fish, but have a number of other projects I'm juggling, so I've waited for a few steps to be done to update.
I epoxied on the rear CR with a stout fillet and then used JB Weld to attach a Aeropack 54mm retainer.
After ensuring that things looked good, I removed the motor retention collar and proceeded to mask off the retainer in prep for paint later.
The lighting reminds me somewhat of a Renaissance painting.
The lighting reminds me somewhat of a Renaissance painting.
High strakes.
So normally I'd be getting a rocket like this ready for paint...
However, the Exocet has long strakes (tunnels?) along almost the entire length of the rocket.
While this is a sport scale rocket, it does duplicate the strakes. Each one is done in two pieces since the rocket is dual deploy with a center break.
I used 30min epoxy and applied the lower strakes to each side and held them down with blue tape.
Next up is a dealer's choice of fun stuff...either:
So normally I'd be getting a rocket like this ready for paint...
However, the Exocet has long strakes (tunnels?) along almost the entire length of the rocket.
While this is a sport scale rocket, it does duplicate the strakes. Each one is done in two pieces since the rocket is dual deploy with a center break.
I used 30min epoxy and applied the lower strakes to each side and held them down with blue tape.
Next up is a dealer's choice of fun stuff...either:
- prime the lower half followed by filler and sanding;
- build the e-bay; or
- start on the nose cone and upper section.
Last edited:
BTW The strakes add a lot of strength and rigidity to the airframe.
This is one sturdy rocket!
This is one sturdy rocket!
keep the pictures coming, great attention to detail 
- Joined
- Feb 8, 2021
- Messages
- 1,472
- Reaction score
- 2,290
Are you going to do a fillet on those? I am thinking about just doing a fillet with tight bond II just to make sure the edges are sealed.High strakes.
So normally I'd be getting a rocket like this ready for paint...
However, the Exocet has long strakes along almost the entire length of the rocket.
While this is a sport scale rocket, it does duplicate the strakes. Each one is done in two pieces since the rocket is dual deploy with a center break.
I used 30min epoxy and applied the lower strakes to each side and held them down with blue tape.
View attachment 560088
Next up is a dealer's choice of fun stuff...either:
To be continued...
- prime the lower half followed by filler and sanding;
- build the e-bay; or
- start on the nose cone and upper section.
Yes! I was planning to as well with Elmer's wood glue, but forgot to mention it earlier. In fact, I almost started it a few hours ago, but something came up.
I actually applied a somewhat heavy coat of epoxy so that it would bond better to the curvature of the bt and wiped any excess off the edges, so the bond is good. However fillets would make it look better and using wood glue should work well since it's wood to the body tube and this should make it a quick job.
I actually really enjoy applying wood glue fillets!
Today I added Elmer's wood glue to the edges of the strakes and smoothed it into a fillet with my index finger. As noted, I enjoy this part of rocket building... very zen for me.
One tip for using Elmer's wood glue (which I much prefer over their white glue) is to steal one of the spouts from a white glue bottle and use that (as seen above).
I also taped off the inside edge of the body tube and stuffed in some paper in preparation for the primer paint.
Looks like rain for the next few days, so paint will need to wait!
One tip for using Elmer's wood glue (which I much prefer over their white glue) is to steal one of the spouts from a white glue bottle and use that (as seen above).
I also taped off the inside edge of the body tube and stuffed in some paper in preparation for the primer paint.
Looks like rain for the next few days, so paint will need to wait!
Ooh...sunny day out!
I had just used up a new can of my favorite Rusto Filler Primer and hunted in my basement for more.
I came across three old cans I had marked with a big "X" on the cap, meaning clogged. UGH.
Finally, I found a mostly full can at the bottom of my boxes of spray paint and initially it was sputtering, but I switched nozzles and I was able to give the rocket several coats before it clogged again.
I think that's enough primer, so after it dries I'll start filling and sanding.
I had just used up a new can of my favorite Rusto Filler Primer and hunted in my basement for more.
I came across three old cans I had marked with a big "X" on the cap, meaning clogged. UGH.
Finally, I found a mostly full can at the bottom of my boxes of spray paint and initially it was sputtering, but I switched nozzles and I was able to give the rocket several coats before it clogged again.
I think that's enough primer, so after it dries I'll start filling and sanding.
Last edited:
BTW I just went by my local hardware store to pick up more of the Rusto Filler Primer, but they were out (go figure).
However, I had sticker shock from the shelf tag... $11.99!
However, I had sticker shock from the shelf tag... $11.99!
Filler up!
I started my usual Elmer's CWF last night. Darn spirals!
I wasn't the most careful since it was late and I figured the bottom half would be all black.
I started my usual Elmer's CWF last night. Darn spirals!
I wasn't the most careful since it was late and I figured the bottom half would be all black.
Half time?
Wait...the Red & Black scheme is half & half at the break, right?
I wasn't the most careful since it was late and I figured the bottom half would be all black.
Wait...the Red & Black scheme is half & half at the break, right?
Similar threads
