Things I learned building my first high-powered rocket

So I'm just about through my very first build and although I wasn't disciplined enough to take pictures and make a full build thread, I thought I'd share a few things I learned:

Painting is a pain and doesn't work when it's too cold outside
Of all the steps painting was the most annoying. So annoying that I might just skip painting my future rockets. I have no garage/workshop so I had to use my (large) balcony. It didn't work very well.

I made a paint booth out of a tall cardboard box to protect my balcony and create a wind shelter. It did prevent paint from getting where I didn't intend it to go but the wind tended to create air vortexes inside the box. Possibly because I live on the corner of the building on the 5th floor and it's extra windy up here.

In addition, it was too cold and humid (0C/32F, 92% humidity). The instructions on the spray can were telling the truth, painting at those temperatures doesn't work well (even using some tricks for cold-weather painting I read about here). In addition, the wind made it feel like the paint spent all the time blowing around my rocket instead of sticking to it. After one coat of primer and two coats of paint the rocket looks barely painted (e.g. you can see the spiral groves in the tube and the pencil marks I drew on it).

Don't over-sand your centering rings
Initially my LOC IV centering rings wouldn't quite fit in the tube (and fitting them was made harder by the tube having been a tiny bit squashed in transport), so I sanded them. Turns out that I sanded the rear ring a bit too much, so much that there was a clear gap between the ring and the body tube which led to epoxy leaking into the body tube when making a fillet. Not a big deal but a bit annoying.

Make sure your fins are really flush with the body tube
One of my fins wasn't 100% flush with the body tube (presumably because the fin tab that touches the motor mount was slightly too long). Again this caused some epoxy leakage when making fillets.

Don't leave your rocket standing outside on a table
It blew over and dented one of the fins.

Things that went well
I followed John Coker's LOC IV guide (https://www.jcrocket.com/loc-iv.shtml) and I really like the improvements he made to the rocket, such as replacing the shock cord and its attachment and using interior fillets for the fins.

Congrats... You finished it. And you actually painted it in winter! Now you've got to go fly it. And the RSO will tell you worst L-1 cert day ever kind of stories of uninformed people saying fins were "snap on" to make you feel better if it starts falling apart before the cert flight. No matter how bad it looks, you glued it and enjoy! And someone somewhere has done worse!

Things I've learned from launching a kit this year were always buy a quality shock cord harness similar to OneBadHawk products or better. It's fun to launch a kit on a Full I motor, but if you want to increase you're chances of certification try to launch on a H motor, because it won't go a mile or more up on an H... Flew a I300T predicted to 5400ft on Open Rocket. Going to fly a H219 Next flight. Pack a bunch of extra epoxy, tools, and shock cord incase the range officer wants you to change your setup at their advice. If winds aloft are real high velocity at altitude consider a jolly logic chute release if your model has a big chute size deploying at apogee to minimize wind drift.

Sounds like you had a more in depth cert examination than I did.

Me "Doesn't the recovery setup get checked?"
Examiner "Did you put a parachute in it?"
Me "Yes......"
Ex "Did you hook it to both pieces?"
Me ".....Yes....."
Ex "Now your recovery is checked, go fly"

Nytrunner said:

Examiner "Did you put a parachute in it?"
Me "Yes......"
Ex "Did you hook it to both pieces?"
Me ".....Yes.....""

Click to expand...

I panicked, a little, when I got those questions. I had to look. My certifiers also asked me the usual and expected questions ("Point at the COP. How long is the delay? Where is the shock cord anchored? What's holding the motor in?") The RSO didn't notice that it was an L1 flight, so I got no hazing about thrust-to-weight or specific impulse.

Its certainly a good idea to have some gap-filling CA, 5 minute epoxy, spare parts, etc. in your range box -- you are allowed to fix it and try again if your first cert. attempt doesn't come back in flyable condition. Best advice I got however; show up with two rockets that can take your cert motor. My "Plan B" rocket became my cert rocket when the Plan A rocket suffered minor -- but not field-reparable -- damage on its G-impulse test flight (the lesson I learned there was not to test-fly your certification rocket) Now that you've done one, the next one should be easy <grin>.

Oh, and I've met a few fliers who don't paint their rockets until they've gone up and been recovered whole. A rocket should earn its colors.

Congratulations!