Does this look repairable?

[Orien]

Or should I just build a new booster? This thing looks pretty effed to me. Worse than i first thought.

 

[tim cubbedge]

You can fix that. I’ve seen worse.

 

[David Schwantz]

Got a great place for a joint. Just cut the tube around the middle CR and use that as the glue joint for either a chunk of new tube or the old one squared off. Will just be 4" shorter than before. If you use new tube add a chunk of joiner above the upper CR to slide the old tube over and then glue. A little bondo and paint, you could even add a new color stripe as that will kind of hide the 2 new joints.

 

[Orien]

Got a great place for a joint. Just cut the tube around the middle CR and use that as the glue joint for either a chunk of new tube or the old one squared off. Will just be 4" shorter than before. If you use new tube add a chunk of joiner above the upper CR to slide the old tube over and then glue. A little bondo and paint, you could even add a new color stripe as that will kind of hide the 2 new joints.

How structurally sound is that? No exterior reinforcement necessary even if considering using 54mm L motors in the future? Next flight was going to be a small K.

 

[Orien]

Got a great place for a joint. Just cut the tube around the middle CR and use that as the glue joint for either a chunk of new tube or the old one squared off. Will just be 4" shorter than before. If you use new tube add a chunk of joiner above the upper CR to slide the old tube over and then glue. A little bondo and paint, you could even add a new color stripe as that will kind of hide the 2 new joints.

Like this? I really only lose 2” this way.


I would need very good bonds between those centering rings and the airframe. I'll probably drill a couple holes and inject it after VERY careful surface prep. Maybe fill the void with two part foam also to bond it to the motor mount?

 

[cwbullet]

absolutely repairable.

 

[David Schwantz]

Yes, that is what I had in my mind. Use good epoxy, remove all the old glue Good luck.

 

[David Schwantz]

Cannot count the rockets I have repaired just like this . Repaired a Mercury Redstone just like this and she flies on a K 550 W.

 

[tim cubbedge]

I would put the coupler all the way down to the lower CR. You should be able to clean it with a Dremel. Maybe drill a few holes in coupler just above the lower CR and inject some epoxy. I’ve repaired similar with fiberglass and it’s stronger now than before.

 

[David Schwantz]

In all honesty, if you just lay epoxy on the inside of the couple after you slide it over the upper CR, and epoxy on the inside at the top, it will form nice fillets as the glue settles. I would not use foam.

 

[Orien]

In all honesty, if you just lay epoxy on the inside of the couple after you slide it over the upper CR, and epoxy on the inside at the top, it will form nice fillets as the glue settles. I would not use foam.

But the coupler tube is the same outside diameter as the CR's. I'd have to sand down the forward CR then grind a step in the lower one with a Dremmel, wouldn't I? That's why in my sketch the coupler is butted up to the forward CR.

 

[David Schwantz]

Yup, I see that. Use a piece of BT instead of the coupler, then no sanding of CRs. Leave BT extended past the upper CR a couple of inches then add your new coupler inside the extended BT and slide the old BT, that has been trimmed square, over coupler down to the new joint. This will also make it the same length as before.

 

[Orien]

Alright! We’re doing the surgery! If it doesn’t work out I’ll just have to put the ol’ girl down. It’s gets easier with each one, though. This would be my third in a row.

 

[dr wogz]

I'm surprised the upper CR is as clean as it is.. Like, the epoxy molded itself to the inside dia of the tube, not actually bonding to it..

 

[Tractionengines]

As everyone else has said. Absolutely repairable. (Don't put her down...)

With the way it came loose from the upper CR and 1/2 the lower CR, a lot of the work is already done.

If you want more support at the Mid CR. You can take a new one and split it in half. Then place the 2 halves around the motor tube above the MidCR. Gives you a double at the splice.
(or)
Cut a coupler to the exact length of open area between Top CR and Mid CR. Then cut it lengthwise so you can flex it open and slip if over motor mount. Tack it with CA in place and tape over slit. Then drill hole to inject some epoxy stand on end. After it's set flip and inject some for the other end. Then put your squared body tube down over with epoxy spread over OD of Coupler. It gives you lots of square inches of bonding surface. All within your original MMT assembly.

Lots of ways to repair this. And everyone has different ways...so pick something that you like and go with it. Should all be strong enough to take most motors. There is lots of support here.

 

[Bowman]

Or should I just build a new booster? This thing looks pretty effed to me. Worse than i first thought.
View attachment 492662
View attachment 492663
View attachment 492664

Piece of cake.

 

[OzHybrid]

The alignment that's most critical is motor. Assuming the motor mount tube has no damage, use a long dowel through the whole thing to keep the motor alignment straight. Fit a temporary centering ring inside the new tube as far away from the join. ( at the new unglued end) just needs to be a good push fit don't glue.dowel through the whole lot. Not seeing any advantage from the coupler. Just adds weight.
From the pictures it doesn't look like you had good bonding with the tube. Measure inside the tube to where your glue joints are going to be and using a bamboo skewer you can get a long way in to apply glue around the area of the joint and pre wet the cardboard tube.
Best of luck. It looks totally recoverable. See below. Your dowel and spacers to motor mount just need to be an assembled tightish fit. No need to glue the dowel in.... and obviously Ive only shown where to pre-wet not the other gluey bits...

 

[Chris_H]

Absolutely repairable.

If need be, just observe for a while and go through the rebuild process in your mind until you see it clearly and are happy with how to move forward.

As someone previously mentioned, it is concerning that the epoxy broke so cleanly from the airframe.

What epoxy are you using? What is your prep method? Why did it fail looking like it never really bonded, especially given that the airframe broke so easily?

 

[Orien]

Absolutely repairable.

If need be, just observe for a while and go through the rebuild process in your mind until you see it clearly and are happy with how to move forward.

As someone previously mentioned, it is concerning that the epoxy broke so cleanly from the airframe.

What epoxy are you using? What is your prep method? Why did it fail looking like it never really bonded, especially given that the airframe broke so easily?

I didn't sand and clean the surface sufficiently. Simple as that.
Edit: or didn’t mix it thoroughly enough. Some of it is gummy on the surface.

 

[Chris_H]

Aeropoxy ES6209 or System 3 T-88 are my fave structural epoxies. I think T-88 can be had in smaller quantities, but it is more particular about accurate mixing ratio. Regardless, if you will be continuing to build rockets, get a scale if you do not have one already.

 

[icyclops]

Or should I just build a new booster? This thing looks pretty effed to me. Worse than i first thought.
View attachment 492662
View attachment 492663
View attachment 492664

Wow, you need to tell us how this thing broke where it did. This is one of the most structurally sound areas of the rocket and usually if it came down hard or motor Cato it would be damaged above the top CR joint….very weird. Please tell what type of launch fatality this rocket experienced.

 

[Banzai88]

Wow, you need to tell us how this thing broke where it did. This is one of the most structurally sound areas of the rocket and usually if it came down hard or motor Cato it would be damaged above the top CR joint….very weird. Please tell what type of launch fatality this rocket experienced.

Holy Catching up to do, Batman.

Start here: https://www.rocketryforum.com/threa...w-with-a-cti-k675-skidmark-wooooooooo.168904/

Then go here:https://www.rocketryforum.com/threa...-100-composite-materials-build-thread.169007/

And finish here:https://www.rocketryforum.com/threa...oy-project-hurricane-is-go-for-launch.169691/

Or just start here:https://www.rocketryforum.com/threa...rricane-is-go-for-launch.169691/#post-2210023

That's where you'll learn that poor surface prep on a glue joint intersected with a parachute selection that was too small, allowing too high of a recovery speed to occur in conjunction with a landing on a hard road surface.

 

[Joekeyo]

Chain of events and errors

 

[Orien]

Chain of events and errors

You just described my whole life.

 

[Joekeyo]

You just described my whole life.

Sometimes I get it right and have only one error or one bad event; otherwise I like to say, "One crisis at a time, please."

 

[Orien]

The alignment that's most critical is motor. Assuming the motor mount tube has no damage, use a long dowel through the whole thing to keep the motor alignment straight. Fit a temporary centering ring inside the new tube as far away from the join. ( at the new unglued end) just needs to be a good push fit don't glue.dowel through the whole lot. Not seeing any advantage from the coupler. Just adds weight.
From the pictures it doesn't look like you had good bonding with the tube. Measure inside the tube to where your glue joints are going to be and using a bamboo skewer you can get a long way in to apply glue around the area of the joint and pre wet the cardboard tube.
Best of luck. It looks totally recoverable. See below. Your dowel and spacers to motor mount just need to be an assembled tightish fit. No need to glue the dowel in.... and obviously Ive only shown where to pre-wet not the other gluey bits...
View attachment 492782

Thanks for the sketch. Makes more sense now. So you don't think the coupler is a good idea? I figured it would give more bonding area and strength. Any suggestions on making the dowel spacers accurately? I don't exactly have a full shop here.

 

[dr wogz]

Thanks for the sketch. Makes more sense now. So you don't think the coupler is a good idea? I figured it would give more bonding area and strength. Any suggestions on making the dowel spacers accurately? I don't exactly have a full shop here.

know anyone with a 3D printer?
A drill press & a fly-bar cutter?

get / use a metal tube (not pipe) these are usually drawn / extruded & pulled, so will be straighter than a wooden dowel..

the coupler is a good bonding / band-aid, but gives little to the overall axial symmetry / concentricity. It's too short to ensure it's all straight.. (Remember, being a .5° off over 6" is negligible. but over 48", it can be significant..)

 

[OzHybrid]

Thanks for the sketch. Makes more sense now. So you don't think the coupler is a good idea? I figured it would give more bonding area and strength. Any suggestions on making the dowel spacers accurately? I don't exactly have a full shop here.

Good preparation of a glue joint is CRITICAL...... There's nothing difficult about the prep. sandpaper/ solvents/ long bits of bamboo skewers( satay sticks) masking tape to stop the glue going where it's not supposed to. You can get more strength from a joint with less glue and correct preparation, than a bucket load and no preparation..... If you are weighing out glue, do it all in the one cup. Measure part1, zero the scales and measure part2 into the same zero'd cup with part 1 in it. If you have a spot of dye that wont react with it, add a drop in and mix until you see NO streaks , it's just an even colour( whatever colour that its.
This avoids getting all of one of the parts out if you use 2 measuring cups then mix. There's always some left in one cup. This gives you a wrong ratio at mixing. I'll stop there as I'm running the risk of annoying the glue gods

Your Avatar doesn't state where you are. We're all going to assume (ass u me) that you have access to a good store. If you let us know where you are and post a picture of your workshop/tool box we'd have a better understanding of your options. Plus we'll know where you live and can pop round to borrow some tools......

Regards
Norm

 

[Orien]

Good preparation of a glue joint is CRITICAL...... There's nothing difficult about the prep. sandpaper/ solvents/ long bits of bamboo skewers( satay sticks) masking tape to stop the glue going where it's not supposed to. You can get more strength from a joint with less glue and correct preparation, than a bucket load and no preparation..... If you are weighing out glue, do it all in the one cup. Measure part1, zero the scales and measure part2 into the same zero'd cup with part 1 in it. If you have a spot of dye that wont react with it, add a drop in and mix until you see NO streaks , it's just an even colour( whatever colour that its.
This avoids getting all of one of the parts out if you use 2 measuring cups then mix. There's always some left in one cup. This gives you a wrong ratio at mixing. I'll stop there as I'm running the risk of annoying the glue gods

Your Avatar doesn't state where you are. We're all going to assume (ass u me) that you have access to a good store. If you let us know where you are and post a picture of your workshop/tool box we'd have a better understanding of your options. Plus we'll know where you live and can pop round to borrow some tools......

Regards
Norm

What do you think of filling the void between the CR's with 2-part foam to lock the joined area to the motor tube and make everything more solid? It's about 4:2 against in my little poll. I can calculate the volume pretty closely and mix less than needed. You can also apply that stuff in multiple (small) batches, too. It's tricky stuff, but I've worked with it before. Wouldn't it make a nice, solid, well adhered segment that is fully integrated into the rest of the rocket?

 

[Sandy H.]

Is the MAC Performance 'canvas phenolic' similar to the PML phenolic tubes?

Sandy.