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

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During build? Probably tacking on fins to my Stratocruiser with superglue and forgetting to fillet one of them. Cleanest popped fin upon landing I've ever seen

I had left all my rockets back home in my garage, packed in a cardboard box.

One of the few advantages of high-power rocket's bulk....you're usually aware of whether they're in the car with you!
 
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..............!


That would've made a pretty decent movie...
Maybe Crazy Jim will tell us about the time he CA'd his phone to his head. Or CA'd his tongue to the back of his teeth... twice!. :oops::D
 
That would've made a pretty decent movie...
Maybe Crazy Jim will tell us about the time he CA'd his phone to his head. Or CA'd his tongue to the back of his teeth... twice!. :oops::D

I'd like to hear those stories about Jim; funny thing is that I haven't thought about my CA/AV Bay issue since it happened until I saw this thread - got another good laugh out of my trials that day........ :)
 
So we are talking build fopaux...
At least they are not as embarrassing as launch fopaux.

I have done most everything here, so I have an inspection check list as I pack what I am going to fly.

Back to builds...
Fins fall off on the pad.
Glued fins on backwards.
Glued booster fins on upper stage.
Glued nose cone on the bt.
Forgot to mount shock cord.
Glued motor mount in backwards.
Glued motor mounts together on a 2 stage.
Epoxied my shirt to my pants.
Got sawdust in my eye and scratched my eye so bad, I had to go to the doc.
Epoxied a rocket to stand.... While separating rocket from stand, I totally bent up the body tube.
Forgot to attach the parachute and watched float away.
Attached tape to the launch rod to lift it off the plate.... The launch lug got stuck and the rocket didn't budge....In front of my 4th grade class.
I am sure there are more, but that is what came to mind.

Next will be Homer Launch Moves, but that is it for now.
 
I build a custom rocket flawlessly with the y-harness recovery bridle epoxied directly to the motor mount.
I then proceeded to drill holes for my rail buttons and decided not to check which side, just go for it.
Drilled right through one of the bridle attachments just above the epoxy so it cut... Now that bridle is only attached on one side. Functional. But damn if it doesn't irritate me
 
Trying to get a scratch 3x 18mm motor cluster built the night before the launch. I was using a screw in the center of the 3 as motor retention so I didn't have engine hooks and so I didn't pay as close attention as I should have. I glued 2 of the tubes into the CRs upside down. Didn't matter much because I forgot to glue on a launch lug too.

Different launch....doing a display for cub scouts. LOC Onyx with an AT G40. I wrap the launch leads around the leg of my pad. I also wrapped the igniter wire around my screw on thrust ring. Rocket goes up about 4 feet, turns 90 degrees away from us and the igniter wire burns through or gives way. Rocket continues to fly about 10 above the ground until it impacts about 100 feet down range on the far side of a pond. Scouts loved it.
 
I have several rockets completed, except, I don't have parachutes installed in any of them. Plan will be to select the right 'chute and install before flight, with minimum packed time to reduce wrinkles setting.

I see a long list of double/triple checks getting all the right parachutes with the right rockets. When there were two or three I had no concerns. No launch in August, so I am up to around 10-12 completed and have started to become concerned.

My worst boo-boos seem to be related to white or yellow glue suddenly making two pieces I have no spares of, one.
 
Didn't really consider that a "build oops", but I feel your pain! Read on:


It was an experience I won't soon forget, so BE CAREFUL WITH CA! :) What an evening..............!
I would have opened the debonder, used it, THEN paid for it :) Bad enough what you went through getting to the Hobby Lobby :)
 
Put a G500 in a 38-29 adapter. When I launched the rocket, the motor went through the rocket. After picking up the pieces, realized the adapter was for the test stand and wasn't glued together. (On the test stand, the motor directly presses against the load cell and the adapter only centers the motor in the holder.)
 
Whats the biggest 'oops' you have made building a rocket?

ive done it once- notice the launch lugs arent on AFTER paint.
ok-twice;i noticed it at the pad once.
but no more than 5 times.
so far.
I did that, too. Estes D-Region Tomahawk. Got the wife and kids out to a sports field, launch pads, controllers, motors. Set everything up, went to put the rocket on the pad and ....
 
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!

You don't need a stop block... use a masking tape thrust ring on the motor, then you are not limited to one motor length...
 
Poured in epoxy around the top of the motor tube/centering ring from nose cone end, put cone in place to hold shock cord up and out of the way of the epoxy. Stood model on table, phone rang, forgot about cat... it got knocked over while the epoxy was liquid, of course the nose cone was pointed downward... had to make the thing shorter...
 
Cut the tube below the shoulder, slit a coupler down the side, spread the couple to get it around the shock cord and then glue it into either part of the tube. The slit really doesn't matter once it's glued in place, but you can patch that if you want.
 
That would've made a pretty decent movie...
Maybe Crazy Jim will tell us about the time he CA'd his phone to his head. Or CA'd his tongue to the back of his teeth... twice!. :oops::D

CA tongue to teeth. Done that. Hey it happens when you need a break third hand to remove cap and use teeth.
 
I remember building my first Astron Explorer upload_2019-8-20_15-6-4.png, initially it was my first level 4 build, i was excited for the build giving it looked awesome, plus a friend of mine actually bought it for our rocket club. So when I started putting it together there were some steps that required me to cut the the rocket. These cuts were small but were not explained by the instructions. I skipped the cutting all together, when i mounted the three side air frames to the rocket, and left them to glue for 4 hrs while i was at a families house, i was talking to my friend about the rocket i was building, i was perplexed as to how the recovery system was to work giving this rock is separated by a 7 inch gap that was initially a smaller rocket glued to the top portion of the rocket. I told my friend about this, he said that the 3 air frames on the side looked like they were how the ejection gasses were to travel to the bottom to the top half of the rocket. I then realized that was why the cuts were made on both main and side air frames. I quickly left the house and went back to see if the side mounts had glued completely. Thankfully they were not, and I was able to take them off and cut the small incisions in which the ejection gas was to flow through. I wonder though, if this mistake did play a role in the first explosion, i do not know but from that past experience I know to follow instructions exactly to point.
 
2 stage High Power Rocket with no room for a parachute in the Booster.. Becoming painfuly obvious at the field..
 
Was working on an Estes "Multi Roc".

Glued the fins on to the booster section. They looked great! Then decided to see how the engine fit.

Uhhhh.. Somehow managed to put an engine thrust ring into the booster section!

Nut wait it gets better! Managed to drive a #11 Xacto blade clean through the body tube trying to clean out the thrust ring and poked the finger!
 
Taking a Carbon fiber 29 and 38mm body tube to a bench grinder with only eye protection on. Got a mouthful of CF dust. That was a painful night.

Next build f*** up.
Had a bright idea to push a Wildman Scale sandhawk way past Mach on a K motor. At this point I had an L1 and a few multistage supersonic rocket scratch builds and some national competitions won. What could go wrong right???

Ran a fin sim and dremeled the fins in a “clipped fashion” to reduce span and flutter tendency. Posted the modification on TRF. Got chewed out that even though it surpassed 1.5 stability cal that fin span shorter than body tube diameter leads to bad airflow around fins and at worst reports of flopping like a whale. Got scared shitless and scraped the idea then sold the kit as is to another member. It was one of those gee this depends and testing may prove otherwise.

Wildman even offered to cut new fins for shipping costs if I promised to not trim the new fins down again, that’s how bad of a build error I made.

Don’t try to make a rocket do something it wasn’t designed to do. Lmao. But yeah anyways...
 
Got a Loc Precision kit build started, got the fins on, got MMT installed, added a ejection charge baffle, glued that in, put on the body tube..and then saw the shock cord laying in a pile. Dammit! Cut the body tube right above the charge coupler, installed the shock cord, added another coupler above that, sanded it and painted it. Didn't look too bad.

Did a launch couple weekends ago. Upscaled Rip-Roar but without the booster. Wasn't windy when I got to field, but setup and wind is batting the 5' sustainer around on 6 foot 1/4" rod. Waited it out until it was just a slight breeze. F engine (I think it was an F-15-6). Hit the button, it roared off the rod, went up 200 feet, turned parallel to ground and became a cruise missile for 300 feet, then a dive down toward the ground.

The very moment I hit the button, a gust came up at.that.precise.moment.

It landed hard, nose cone down into the ground. Little time for ejection charge, so no chute. Surprisingly, very little damage, cleaned up the nose cone, repainted it and put it back to work.

Wind is not kind to F engines. They need absolute calm and no gusts.

Once glued a booster and sustainer together. Didn't realize it at the time. Fired it off, it came down just perfectly fine. What USED to be the booster was charred and burnt up through the booster MMT.

Did a scratch build from leftover parts. Got it all together, sanded, primered, final paint. Looked it over and realized I had forgot the launch lugs. Got the dremel out, sanded down 3 spots, glued in the lugs, spot repainted those areas.

BT Zippers - ugh! Tried thin and thick cords, tried drilling hole through a hard ping-pong ball for shock cord to go through for top-of-tube. That semi-worked. The force of the ejection split the ping pong ball but no zipper.
 
Wind is not kind to F engines. They need absolute calm and no gusts.


The 29mm blackpowder F motor from Estes has rather low thrust in the first part of its burn. When it comes to launching larger rockets, look at the thrustcurve of the motor you want to fly, and how fast the rocket is going when it leaves the rod/rail.

Thrustcurve.com is your friend
 
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