Astron Elliptic II Build Thread & Repair Question

Hey all:

Wanted to share with you all some pictures of my first two-stage build (and only my second kit ever that's not RTF). I've gotten lots of help on good building/finishing technique already from searching this forum, so enjoy the pics knowing a ton of you helped out in a BIG way!

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Here's the motor mounts, done with yellow wood glue. I plan to use epoxy from here on out in my building.... Lots of guys on here prefer it, and my next build is a Vagabond which has a ton of power compared to these 13mm kits!



Next step was FnF'ing all of the balsa - I think I might be able to sand it down a bit more next time, but it was smooth and I was pretty happy that paint would stick to it. This forum was a huge help for all the pre-finishing steps like this one.



While my FnF was drying, I glued both motor mount tubes into their respective stages and put some glue on for the double glue joints. In hindsight, I should make these initial lines smoother... Afterwards, the body tubes after fin attachment...



Heres the entire rocket pre-primer. I skipped uploading separate pictures for FnF'ing the body tube spirals and cementing the nose cone hook on.



Three coats of primer and undercoat white, each one wet sanded with 220,400, and 600 grit respectively produced this intermediate step. My paint was Krylon's gloss white enamel (IIRC it's called Colormaster). I did my first build with Tamiya lacquer and I really, really, REALLY would go back if it wasn't for the cost. Canadian Tire (yes, we do fly rockets in the great white north) has a large can for $4.99 compared to $11.99 for 1/3 the volume of tamiya at my LHS, and $12.99 for duplicolor at NAPA auto parts. Ouch!



Here she is after Rusto Gloss Black, decals, and Rusto Clearcoat finish. I wanted to try masking the little squares at the top for a little bit more of a finishing challenge, and pretty happy with the result other than some bleed on the square edges. Could be a bit more glossy, but I didn't exactly follow the drying time between the black and the clear coat.... Got super antsy to get out and fly!



Next stop, the maiden flight!!!

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I built my own launch pad as a side project, using a lot of the cool ideas and recommendations from other launch pad threads on this forum. Specifically I loved the drill chuck ideas, as well as the camera tripod for stability and angling in any wind. Here's a shot from my phone right before the first flight.



And an absolutely fantastic action shot of liftoff. Photo cred to my dad and his DSLR.



I used the A10-0T for the booster stage (only option), and the 1/2A3-2T for the sustainer. Unfortunately no video of the entire flight, but she flew straight and true. Separated and ignited the sustainer almost perfect, with only a small deviation from intended trajectory. However........... On ejection, the streamer came out tangled in the shock cord (I used the standard length Estes elastic), and it descended on an angle with almost no air resistance being provided by the streamer. Landed on an angle, down on a hard concrete running track, severing one of the fins off the body. Here's a picture of the break.



Looks to me like the cardboard tube actually ripped, rather than my glue joints failing. Here's where I was hoping you guys could help me once again - I need some guidance in repairing the fin break so I can get her back on the pad. I was thinking that I'd use coarse grain sandpaper to once again make a smooth surface on the fin itself, and try to level out the body tube as much as I can. However, since I've already applied a double glue joint to the root edge of the fin, am I going to be in trouble since the pores of the balsa are going to be "locked up" already? Maybe if I used CA or epoxy I could get a good bond?

This kind of stuff is where experience pays big dividends and I would be grateful for some guidance on both re-building and re-finishing (this step is less important).

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I also have a more general question about the recovery system in general... I attached the streamer onto the shock cord using clear tape as the directions state, probably about 6" from the nose cone. Would I be able to avoid the problem of the streamer becoming tangled by moving it closer to the nose cone, or rolling it up looser?

I'm also thinking about replacing the entire shock cord with a longer section of nylon or Kevlar braid as a lot of the threads on here recommend - what would you recommend for length, as well as the best way to remove the existing cord mount for replacement??

Thanks a Ton for any advice you guys can give me. Hopefully you enjoyed the pictures. Can't wait to fix this baby up and get started on my next build - rocketry gets very fun, very fast.

Very nice build! This is going to be my son's intro to 2 stage rockets, I love the lines on this one.

As for the questions that you have, I'll tell you what I would do starting at the end and working back.

If you built it stock with the tri-fold shock cord mount just stick with it on this kit. It should work well enough here and just replace the shock cord with sewing elastic if it starts showing signs of needing replacement.

I accordion fold streamers when I can and try to keep them on top when packing the recovery gear. I like to tie a small knot in the end of the streamer, capture it in a loop of the shock cord and secure it with a bit of CA glue or left over epoxy. I think that your placement is fine.

As for the fin repair, I would just use epoxy and simply ensure that there is no loose material that may weaken the joint. When I do a repair like this, I make fillets using a mixture of epoxy and balsa dust. I like CA for a quick field repair here but CA does not have good shear strength and I prefer other materials when I have the time.

When masking for color accents, spray a light coat of the base color to seal the edges of the mask and then spray the accent color. Using the same label paints makes this a much easier process. If you have any questions concerning compatibility, wait several days between colors and trim the edges before removing the mask.

I used nothing but Titebond II to build my QCC Explorer and it has had 4 flights on E motors with no issues. Personally, I wouldn't bother with epoxy for low power rockets.

That's my 2 cents. I try to keep things cheap and easy and am only a 2nd year BAR. There will be others with much more experience than me to chime in here and I will be reading their comments and suggestions as intently as you.

Screaminhelo said:

As for the fin repair, I would just use epoxy and simply ensure that there is no loose material that may weaken the joint. When I do a repair like this, I make fillets using a mixture of epoxy and balsa dust. I like CA for a quick field repair here but CA does not have good shear strength and I prefer other materials when I have the time.

Click to expand...

Thanks for all the advice. I just got back from flying with the epoxy repaired fin, and she flew beautifully! I didn't know what you meant by balsa dust, so I just lightly roughed up the surfaces with 220 grit and went a little overkill on the fillets.

Believe it or not, this flight was the exact same outcome.... Broken fin right off the cardboard. Landed once on a narrow section of concrete in a big field full of nice soft grass.... I've broken fins before on my rockets, but in every case it's clearly been a glue joint that failed or a balsa break. These cracks seem to me like the hard enamel finish on the rocket is cracking up the entire cardboard surface, taking the unfortunately placed fin with it... But I'm so new to building and finishing rockets that I'm essentially speculating just based on the fact that these breaks look like nothing I've seen in my past launches.

Here's a picture of the break - do you have any ideas as to why I'm seeing this pattern on relatively slow impacts?? (You can also see my overkill epoxy job, hah! I'll be much more precise with this repair.

Thanks in advance!

Estes tubes will delaminate pretty easily on impact, especially if the fin is glued only to the outermost layer. One thing you can do when building to make this a lot less likely is to sand off or peel away the outer layer of tube before attaching the fins. This will let the glue penetrate through the inner layers of kraft paper, making a much more solid joint. I often do this with a Dremel sanding drum.