A (lenghty) follow-up message for all who may be interested.
Bottom Line Up Front: We had a successful launch after a week of repairs! Video link at bottom of this message.
When the launch failure occurred last week, I had no idea what the problem was. I was hesitant to try it again without knowing root cause, so I wasn't sure we’d ever launch the Saturn V again. Thanks to all the replies on The Rocketry Forum. With the conclusion of Bernoulli Lock, I was motivated to try again with confidence of success.
There was more damage to the rocket and support equipment than I originally realized. Here is a list of the damage and the repair details:
1.) Bottom of rocket was burned to a crisp. This included the plastic fins. I cut off about two inches of the damaged body and peeled off the melted plastic. (The motor mount is recessed about 3-½ inches, which made this trim job possible.) The lower disk for the motor mount was also badly damaged, so we cut a new disk and glued it in. We knocked off the ashes and charred bits, and gave it a quick primer coat.
2.) The fins were melted beyond repair, so we had to improvise. We cut out some replacements from a heavy duty plastic notebook cover. We tried to keep the same form factor. Once they were epoxied firmly to the body, I knew we had a chance to relaunch.
3.) One of the two parachutes for the main body was melted. The ejection charged blew the nose cone, but one of the parachutes stayed in the main body. (You can see this in the previous video, only one pops out.) The body tube acted like a chimney and the hot gases from the fire below melted it. I found an old plastic shopping bag that was hearty enough to make another parachute. Appropriately enough the bag was from Lakeshore Learning, a popular children’s educational store.
4.) The launch pad suffered damage too. During the failed launch, a hole was burned through the deflector plate and melted a hole hole on one of the plastic launch legs. Also, one of the plastic stand-offs that holds the plate was severely melted. The hole in the launch legs was no problem, merely a flesh wound. But I replaced all the stand-offs ¼-20 machince screws.
5.) As someone previously pointed out in the failed launch, the top stage “lawn darted” and the tip assembly was basically destroyed. I pared the assembly structure and epoxied the tip back on.
6.) Since the CG and CP were changed by modifications, I checked their locations for stability. Surprising, they were way too close (basically in the same place). To get about one caliber separation, I added four sticks of modeling clay (I think this was about 12 to 16 ounces, does that sound right??) in the nose cone. I have my suspicions that the original design was not weighted properly (but that’s a story for another thread. I have an Estes Patriot that was way off.)
7.) I didn’t realize until we were ready for relaunch, but the wiring assembly near the ignition alligator clips was torched too. The clips were completely coated in rocket exhaust residue, and the insulation was burned off and melted. Luckily I had a set of clips from my other launcher in the kit box. A quick splice job, and we were ready to go!
Oh yeah, we wrapped some tape on the launch rod, so the rocket had some space above the deflector plate. No Bournelli Lock for this launch!!!
We went to the high school and had a bit of an audience. The local softball team was prepping for a game. You can hear their “cheers” and “woo hoos” in the video. Good times.
Here is a link to the launch video.
https://youtu.be/43nfDzo4jyM
Sorry we don’t have the full flight!
Thanks again to everyone’s contribution here in solving the mystery. Our rocket has many launches in front of her. BTW, since this Saturn V has been modified so much, we have changed its name. We now call her “Phoenix 1.”
We are going to repair the bottom end of this Rocket and put some customized fins on it. I'll make sure the CP and CG relations are correct, and then try to launch it again with a GAP between the pad and rocket. Pinker and better than before!!!
