Blue Stage - High Power Two Stage

Nytrunner said:

Good jig.

What do you do to ensure the slots are 90deg?

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Even though the sides are slanted, they are both slanted the same so the height of both sides above the base is the same and that keeps the sled parallel to the base and the bit going straight down. Also, the sled is designed with the router bit centered between the rails. I marked the locations of the fins on the tube using a guide I printed from Open Rocket. I align the router bit to the marks on the tube by putting some finger paint on it and lowering it with the power off until it touches the tube.

I've made more progress on this rocket in the past few days. For now, I'm still working on the booster. I glued the upper two centering rings onto the MMT and I also added a U-Bolt to the upper MMT and sewed on a 3 ft. length of tubular Kevlar. Then I glued the MMT into the booster body tube. Here's a picture of the MMT with it's upper centering rings and the Kevlar harness:

After this, I cut a fin alignment jig out of some poster board and glued in the first fin. I used a template printed from https://community.rocketreviews.com/?app=tools&tool=finguide to layout the fin jig. So far I've only cut out the slot for the first fin, but, it has lines for all four and I will cut out the others as needed.



I used 30 minute epoxy to glue the rings to the MMT since they were cardboard and plywood and the 30 minute epoxy should be stronger than the material. I used Aeropoxy ES6209 to glue on the fin since it is thicker and forms better fillets and it also connects to the Blue Tube air frame. For the fin, I used the triple-dip technique, where you put a good layer of epoxy on the fin root, insert it, remove it, and then repeat twice to form the beginnings of an internal fin fillet.

In addition to the above progress, I ordered some 1/2" tubular nylon (TN) to use for the recovery harness both for the booster and the sustainer. I'm going to use Kevlar next to the MMT for heat resistance and then use the TN for the rest of the harness so it can stretch a little if needed. I'll have a ball-bearing swivel between the Kevlar and the the TN so things won't tangle up as much if the fin can spins.

I've made some more progress on this rocket. I've got the fins glued on the booster and I've sanded and glued together the end caps for the electronics bay. Here are some pictures of the fins and lower centering ring on the booster. Note that I glued in the MMT with the two upper centering rings and left off the bottom centering ring until I could add internal fillets. Also, I've switched from AeroPoxy ES6209 over to RocketPoxy. I really like the AeroPoxy, but, when I opened my new package of it (which I ordered last year) I found that somehow I ended up with two cans of part B and no part A, so, I figured it was a good time to try out RocketPoxy. So far, it seems the RocketPoxy is a bit easier to work with as long as you let it set for a bit once it is mixed.

Slowly but surely I have made progress on this. I've cut the fin slots and fins for the sustainer and I've built the avionics bay that will handle the sustainer deployment. I've spaced the all-thread in the avionics bay so that I can move the altimeter sled (with an Eggtimer Quark) between this rocket and my MAC Rayzor. Next I'm going to work on sanding fins and the lower avionics bay which will handle lighting the sustainer. Below is a dry-fit picture both stages together.....in comes in just shy of 8 feet tall.

Here are some pictures of this rocket mostly completed. I launched the sustainer this past weekend and it worked quite well. The shroud towards the top covers a key-fob HD camera. Hopefully I'll get to launch both stages at Battle Park in October. The nose cone has a 38mm nose cone bay (from MAC Performance) for the GPS tracker.


Here's the electronics sled that will light the sustainer motor. Note that there will be a zip tie near the top of the electronics sled to help hold it in place. Also, note the "remove-before-flight" pull pin switch that will safe the igniter for the sustainer until it is on the launch pad. The hatch that covers this has a tongue and grove design that slip fits at the top and has two screws at the bottom to hold it in place. There is an aluminum tube from this compartment down to the bottom of the rocket for the igniter wires.

Amazing paint and stickers

Come back with video!

Today I successfully launched this rocket with an AT I600 in the booster and a CTI I540 in the sustainer. Both stages lit and it made it to about 4800 feet. It didn't drag separate, but, the booster came off fine when the sustainer lit. I had coated the inside of the stage coupler with thinned JB Weld and that worked to protect the booster from the sustainer motor. The booster landed not far from the launch pad. The recovery system worked well but the sustainer did drift about 1/2 mile and land in the top of a 70' evergreen tree. Once located, I called a local tree climbing expert who had no trouble recovering it. Next time I'll use my tracker so I don't have to search for 45 minutes. I'm attaching a video from the on-board camera....

Nice flight! My hat is off to your fin alignment skills. It hardly rolled at all on boost.

Ditto on the minimal roll!

Very nice flight.

Where do you find a “tree climbing expert” on short notice?

BABAR said:

Ditto on the minimal roll!

Very nice flight.

Where do you find a “tree climbing expert” on short notice?

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Thanks on the roll compliment, I spent lots of time trying to ensure the fins were straight.

I got the number for the tree expert from one of my fellow club members who had used his services earlier the same day to retrieve one of his rockets from a tree after its 49th or 50th flight. Fortunately, the tree climber didn't live far away, so, it only took him about 15-20 minutes to arrive and less than 45 minutes to retrieve the rocket.

Today I launched this for the third time. Today's launch was an I540 to and I345 and it reached about 4100'.

Last month I also launched it, but, only the booster lit (it was a J350->I345). A post-launch investigation revealed that the criteria I had set to light the sustainer weren't met even though everything looked optimal. Some of the vent holes for the sustainer-lighting electronics were partially obscured and there was a bit of a breeze, so, I think it may have been getting false readings. I use an Eggtimer Quantum to light the sustainer and it logs everything so it wasn't too hard to troubleshoot.

For today's launch I made sure the vents were clear and I also increased the pre-launch sample rate to 30/second and everything went as planned. My OpenRocket simulation predicted about 3800' and it reached about 4100', so, it wasn't too far off. I think some folks took video, so, I'll link that here once I find it.

Here's a link to a video of today's launch. Towards the end, you can see the booster near the bottom of the screen and the sustainer at the very top.


The above video is one that I took. You can also find another of my rocket and many other good ones at: https://www.youtube.com/channel/UCqDx0STHeh2LXMtOiEkl2DQ

Yesterday I launched this again using an I435 (Aerotech) to an I285 (Cessaroni). Everything went well and it reached about 4100 feet. The simulation called for about 4030, so, it was close. The sustainer drifted toward the trees, but, fortunately it landed on the ground between the small trees and the large one. I'm thinking, for next time, I may re-work it a bit to add a stage separation charge. The staging computer can handle another channel, so, it is mostly a wiring problem.

Pretty cool flight above. I have to agree that that is one nice slotting jig.