Whats the biggest 'oops' you have made building a rocket?

I have plenty of them, crooked fins, epoxying fins to an alignment jig.

Today I pulled one of my biggest oops!

Working on a Estes Plasma probe and nearly had it completed. I took out the little plastic bag that had the shock cord, chute, and ~gasp !~ the engine stop block!

Yep the entire model was assembled and I had forgotten to put the stop block in there! Fortunately the design of this model has a short lower section BT55 about 4 1/4" to the top of the motor tube. I managed to mix some 30 minute epoxy for plenty of working time, slipped the stop block on the end of a small screw drivers handle and putzed around with it forever getting it lined up and pushed into place, but I did get it in there!

If it had been a smaller or longer tube I woulda been stuck!

The first design (age 11 or thereabouts) that I actually built was more or less like a WAC Corporal but with 18" airframe and four fins. Glued fins in place, did a swing test, rocket fell about three feet and a fin broke off. Cut out a second set of fins and glued them to the original set. This time TWO fins broke off when the rocket fell. Had no idea what was wrong. After all, the grain should be parallel to the airframe, makes 'em more streamlined, right?...

On another occasion I discovered that when using a metal ruler as a guide for cutting fin stock, the fingers holding down the straightedge should NOT overlap the edge of the ruler...

Best -- Terry

One of my biggest blunders happened recently while I was working on my Apogee Saturn V. There is a really nice wrap for the service module with raised markings. Well, I tested for fit, marked the wrap for top and bottom and then proceeded to put it on upside down anyway.
I considered peeling it off and getting a new one but I didn't have time (I was trying to get it ready for the July 20th anniversary launch). I ended up carefully cutting it off and reattaching it with a spare coupler I had.

Getting the forward and middle BNC-50 swapped on the Trident II.

Heh those re some good ones!

I glued the fins to the wrong end of a tube once. The motor mount was already installed

I tend to make many small ones and (so far) avoid the Big Oops.

I did however have a couple of infuriating incidents in my IRIS-T build, both of which came after the model was painted and decaled and almost finished.

First, I knocked the whole thing off my PVC stands, and broke off one of the tail fins. I seem to knock rockets off my stands fairly frequently, but this was the first (and so far, only) time I actually caused significant damage to a (nearly) finished rocket. Required a lot of paint touch-up to make it look OK, still far from perfect. I was.... not happy.

But that didn't even compare to the expletive-inducing rage of when I put a hole in the side of the body tube, right through the logo decal. I had been trying to install a homemade laundry shelf in there, and once it became clear that the whole thing was a failure, I needed to pull it out before it became glued in. I used a wire hanger with a hook bent at the end, and as I was pulling on it, the end of the hanger hook grabbed the side of the BT and went right through. I had to step away for a few days before I had cooled down sufficiently to be able to effect a repair.

I JB Welded a Slim Line retainer on backwards. Was able to remove it before it fully cured with heat gun but was a pain getting all the JB Weld off the threads.

There is someone who used coupler tubing instead of motor mount tubing....didn’t realize till trying to insert a motor....not me, by the way.

2014 box of parts contest.

Buzzed Lightyear
https://www.rocketryforum.com/threads/buzzed-lightyear-box-o-parts.62918/
Test fit the motor too soon after using CA on the mount.

GLUED the motor in (there’s Positive motor retention for you!)
So rocket flew one time

Overdrilled a delay on my Mustang, torched the guts out.

Repaired a cracked fin on a booster with thin CA and accidentally glued the booster and sustainer stages together.
Heh.

What, today?
Went to launch a scratch build without any launch lugs.
Once attached myself to a Sunward Starwatcher with CA. The debonder was in the car. At the mechanic's workshop. Nice walk of about 2 miles with a half built kit attached to my left hand.

Cape Byron said:

What, today?
Went to launch a scratch build without any launch lugs.
Once attached myself to a Sunward Starwatcher with CA. The debonder was in the car. At the mechanic's workshop. Nice walk of about 2 miles with a half built kit attached to my left hand.

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Oh! You reminded me of when I learned how to get expanding polyurethane foam off my hands.

Used canned foam in a fin can. All was fine until I set the rocket in the sun; it looked like it had the mumps!

Brought several unflown rockets to a club launch, looking forward to flying one of the biggest I have which still hadn't been flow since I'd built it a year previous. Brought it to the table to pack with dog barf and as I pulled the nose cone off I saw that I'd failed to finish that one and there was NO parachute or cord in the tube. Didn't fly it that day either.

Went to a launch to fly a new build before painting. Go to put the motor in. Something doesn’t look right. 3 fins on the right way, one upside down. They were close but not quite.

timbucktoo said:

I JB Welded a Slim Line retainer on backwards. Was able to remove it before it fully cured with heat gun but was a pain getting all the JB Weld off the threads.

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I did that recently. Didn't notice until I couldn't screw on the cap. I had to cut it off and grind/chip/dremel the JB weld off. Fortunately there was enough motor tube left to attach it the right way.

Wow, there are some great anecdotes on here. Good to see I'm not the only one

JB-Welded an Aeropack 54 retainer backwards to a FG motor mount. I caught it the next day, after the epoxy had cured... couldn't get it off, so I had to buy a new retainer and motor mount tube. I still have it... numerous attempts to remove it using various forms of heat have been unsuccessful.

Done this twice with estes MPR kits. I just wanted to save time and put the mmt in at the same time as the fins. With mpr kits it isn't a big deal though because adding tape isn't that hard

cerving said:

JB-Welded an Aeropack 54 retainer backwards to a FG motor mount. I caught it the next day, after the epoxy had cured... couldn't get it off, so I had to buy a new retainer and motor mount tube. I still have it... numerous attempts to remove it using various forms of heat have been unsuccessful.

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I have removed several by applying direct heat with a propane torch. Was also able to remove most of the epoxy (JBW) with wire brush while still hot. Mostly just some patience.

cerving said:

JB-Welded an Aeropack 54 retainer backwards to a FG motor mount. I caught it the next day, after the epoxy had cured... couldn't get it off, so I had to buy a new retainer and motor mount tube. I still have it... numerous attempts to remove it using various forms of heat have been unsuccessful.

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I've salvaged the base portion of Aeropack retainers (for crashed or otherwise unusable rockets) by cutting the base off just above where it is JB-welded to the motor mount tube, then using a small grinding tool on a Dremel to grind out the remaining motor mount and get to the cured JB-Weld. Once you're to the weld, you can pick it out with all sorts of small scratch awls and other strong, sharp tools. It will kinda chip off once you're to the weld itself, and you don't have to worry about scratches in the aluminum cap because it's just going to be re-welded at some point in the future...

My biggest "oops" happened about seven years ago building an Aerotech mid-power kit that called for CA on the coupler tube. Well, anyone that has done any work with CA (thin CA) knows that this stuff grabs in an instant!
I got the coupler in the booster section, but not quite in half the length of the coupler, then put a bunch of thin CA on the coupler to slide the payload tube down on the coupler. Well, the payload tube stopped during the install about 3/8" from meeting the booster section and I it was done. There was NO WAY that payload was moving forward or backward at that point... :-(
So, instead of scrapping the rocket/build, I got creative with a fiberglass patch to fill the 3/8" wide groove around the middle circumference of the rocket, sanded it, primed it, painted it...
I learned from that and ALWAYS consider just how fluid an adhesive is going to be when joining two large areas that must move against each other before getting to their final install point... :-|

I roll my own fiberglass tubes including the motor mount. Took a new 3 inch scratch built rocket with a 54mm motor mount and had the whole thing prepped and ready to go except the motor mount tube was just a little too small for the motor. I hadn't double checked the motor fit until I was about to launch it.... I did manage to jam a 54 to 38 adapter into it and flew it on a 38 mm motor.

Cape Byron said:

What, today?
Went to launch a scratch build without any launch lugs.
Once attached myself to a Sunward Starwatcher with CA. The debonder was in the car. At the mechanic's workshop. Nice walk of about 2 miles with a half built kit attached to my left hand.

Click to expand...

Didn't really consider that a "build oops", but I feel your pain! Read on:

In the last few months, I was working on a 4" Bluetube AV Bay that has a paper stiffener inside and needed some CA in the shear pin holes. Well, I was holding the AV Bay on the outside and didn't notice the CA oozing out the holes as I saturated the inside paper. I then used my other hand to rotate the AV Bay to do another hole and didn't feel the CA all over the outside of the AV Bay at my new grasp point. Needless to say, I didn't need to grasp the AV Bay any longer as it was FULLY bonded to my thumb, index finger, and the web of skin between the two fingers!

I was out of Un-Cure, but Hobby Lobby was still open. Now, here's where it gets funny. The AV Bay was stuck to my right hand, and my girlfriend was not home to take me to Hobby Lobby. I did have my cash and keys in my pocket, but they were in my right pocket... Anyone that's ever tried to get something out of a right side pocket with their left hand (or vice-versa) can appreciate the comedy I was doing in my driveway trying to get to my keys Eventually, I reached them through a modified method of getting my cash, that I'll explain further down, and was able to get in the truck. But now I had to insert the key into the ignition with my left hand and get the truck in gear - try that sometime; try to get your keys in the ignition with your left hand and then try to move the shifter from Park to Drive...... At this point I was pretty amused, but it got better when I arrived at the store.

Inside, I looked like everyone else shopping for items to purchase, but then I got to checkout. Remember my cash was inside my right pocket and I have a 4" diameter, 8" long coupler glued to my right hand. I started to try to get to my cash just before I was with the clerk, but realized it was not going to be an easy task. After looking like I had some birth defect trying to get my left hand in my right pocket a few times, I was getting some weird looks for sure, even had a guy offer to "help" me in my pocket - no thank you sir; I'll get this one on my own!

I wasn't having much success, but then I hit on the idea that trying to massage the folded cash up my pocket might work if I use the edge of the counter. After about 30 seconds of looking like I was doing a lap dance with the counter, I realized that wasn't going to work, AND I was at a counter that was to my left, so I was facing customers in line behind me while trying to "massage" my money out of my pocket - LOL! It was a sight I'm sure. Running out of options short of having some guy I didn't know in my pocket, I started to think about the large item attached to my right hand and the edges it has on it. I started working the AV Bay against my right thigh while trying to get my left hand into my pocket. I rotated my jeans as far to the left as I could, putting my zipper about 3" to the left of where it should be, then working the AV Bay up to push my money up. Well, that put my pocket and my efforts just about over my tool, so, needless to say, I had a very amused audience by now. Also, I looked like I was working on myself for my own pleasure in line at the Christian-owned Hobby Lobby on a Saturday night, just to get some cash out of my pocket so I could go home and un-couple myself from an AV Bay.

Eventually, the combination of rubbing myself with the AV Bay in an upward direction, my jeans cranked to the left, and my left hand trying to get in the pocket worked, and I was able to reach my cash and pay for my purchase before leaving the stage. I took a bow, and offered that I might come back for a repeat performance next week, but that they shouldn't count on it... Considering that all of this happened in about a 2-minute span while in line makes me laugh about it to this day.

I had put my keys in my left pocket while I shopped, but I still had to get the keys in the ignition again and move the shifter to R then Drive. It's much easier the second time around, but still awkward to move a shifter putting your left hand through the steering wheel to be able to reach it. Yes, I made it home to start to work to remove the well-bonded AV Bay/hand combination. My girlfriend arrived home shortly after and I recounted what had happened. She laughed so hard that I thought she was going to wet her pants, but she didn't thankfully. After we stopped laughing, I continued to work on the uncure process which took no less than an hour.

It was an experience I won't soon forget, so BE CAREFUL WITH CA! What an evening..............!

OK was never going to tell anyone about this, but i glued the motor mount into the wrong end of the body tube on my Estes Nike X build.
Wonder how it would have flown with the nose cone coming out of the fins.
Tried to fix bit wound up trashing it and starting over, luckily it was a 12.00 kit. DUH

Not sure if this is the biggest but I made an oops last week when I painted the white on my booster before I put the vent holes in. This morning, I remembered them again so I put the vent holes in with my Dremel tool. I figured right above the fins would be great because I could use the fins to get the spacing correct. So I made the vents. Cleaned them up with the X-acto and sand paper and I got them all painted. I was really impressed with the paint and decided I wouldn't have to re-spray, that the touch up with a brush came out really well. Then I put the booster on and realized my mistake...

The vent holes line up with the upper fins so there's a possibility of scorching the fins and decals now. I think what I'll do is display it like this, but turn the fins 60 degrees just prior to lunch. So it's one oops on top of another...



-Bob

A few years back I drove all the way to the Orlando ROCK field for a monthly club launch.
For me, it's about a 45 minute drive.
I opened the trunk of my car and realized -
I had left all my rockets back home in my garage, packed in a cardboard box.

Now I always put a few BT-5 rockets into my old range box to make sure I have something to launch.

Let's see ... 8" FG rocket, $1000 into the build. Time to insert the MMT and CRs into the booster. Have threaded rods thru the CRs, and have to align the MMT so that the T-rods do not block the fins slots. Epoxy up the edges of the CRs, slide it in ... and behold, I put the fin slots right, directly in the way of the CRs. Just completely brain-farted when I actually did the work.

Quick, mad dash to get gloves and a 2X4, bang the MMT back out far enough that I can grab a CR and spin it, shove it back in before the epoxy starts to set. Fortunately, it all worked out in the end.

At last NSL, I had prepacked a rocket (motor, wadding, streamer) with some masking tape over the nose cone-tube interface, to keep the nose cone and innards in place during transport and on the way the pad. Unfortunately I didn't notice the tape, even at the pad, and launched it. Rocket did the best it could, but a taped nose cone doesn't come off, and it playa-darted.

I now have picked up some pink masking tape, pretty cheap, and I put on a long enough strip that hopefully I won't miss it again. Here is an example.

Dwatkins said:

Went to a launch to fly a new build before painting. Go to put the motor in. Something doesn’t look right. 3 fins on the right way, one upside down. They were close but not quite.

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It would've flown fine. Probably.

SammyD said:

Anyone that's ever tried to get something out of a right side pocket with their left hand (or vice-versa) can appreciate the comedy I was doing in my driveway trying to get to my keys

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Next time this happens ( ) go back into the house and take your pants off. Even that is a bit of a challenge with one hand, but a lot easier than getting the keys and money out of the wrong side. Remember to put them back on before heading out.

I built a five engine rack rocket, my most ambitious project up to that time, and forgot to attach the shock cord on the airframe end. The up was OK, and the nose cone came down under chute...

Built a Quest Terrier Orion and left the launch lug off. And didn't discover it until I was at the launch. The same launch as the rack rocket. I'm sure some people left thinking "what that schmuck!"