Makers Corner

Well, Money it tight these days and not getting looser so I'm looking at ways to save money on my next rocket build.

I recently purchased an AeroTech M1340W-PS 98mm x 557mm Single Use DMS from Wildman ($800!) for use in my Level 3 rocket. This next build will be designed around a motor this size.

I've got two L3CC's to support me with the L3 requirements and some other folks that will be reviewing my plans. I'll post more details to this thread as I make my way through the build process. I've attached a "Strawman" document that outlines the initial thinking behind what I'm going for on this build. Feel free to make comments, but understand this is just a planning document, it's not a design. That will come later.

The next step for me is to create the design documents an get approval from the L3CC (Dr. Stephen Boy with Richard F Comshaw PhD APRN in a supporting role) so I can begin construction. However, in the interest of developing a process for making my own tubes, I'll be constructing a 98mm motor tube using the new M1340 as a mandril stating as soon as late next week.

For the avionics, I've settled on the BlueJay Altimeters. After using several of the different altimeters available on the market, the BlueJay has proven itself and features like the magnetic switch and iPhone application that allows me to test and control the computer make this system very easy to use.

Other than those purchases, I'm really just at an academic level right now writing things up and developing an OpenRocket model which i'll share once it's complete. In the meantime, enjoy the Strawman and I'm going back to studying!

Best wishes for your build. I loved the experience of building my L3 "Future So Bright" rocket.

Rick Comshaw was my L3 TAP so you'll be in good hands with him.

You may need to include two different altimeter types, possibly from two different manufacturers. I don't recall if this is a requirement but it does eliminate risk due to firmware or hardware issues being identical between the two altimeters.

I love the Blue Raven altimeter. I'm not familiar with the Blue Jay but I've had great experiences with everything from Featherweight. For my second altimeter, I used the TeleMega. I like the hardware but I found the data recording of firmware/software a little buggy compared to altimeters from Featherweight and PerfectFlite.

I have my L3 doc online here: https://drive.google.com/drive/folders/1z8dTLR_xNv8UgpxASwqsrPA5r0QlSnyw?usp=sharing

Jim

PS: Rick shared with me that the major advantage of being L3 certified is that "You can now talk shit about anyone else's rocket design".

Good luck on your L3 and looks as if you have a well thought out plan.

My only advice (and feel free to ignore)... keep it simple, in particular for an L3. So, I would recommend buying COTS tubes rather than trying to roll your own, unless you have done it a lot already. You might save money (mmm, maybe not for the first one though) and it could potentially eat up a lot of time and several tries to get it right. Alignment and strength are two key things you want to get correct for an L3.

If you insist, however, I recommend using a carboard MM tube and then getting a fiberglass or carbon fiber sock from soller composites. The socks just stretch over the cardboard and in my experience, it's pretty straightforward.

Curtis

Yes! I agree with Curtis' advice re: buying a commercial tube (I used a PML 7.5" phenolic tube) and ESPECIALLY the Soller Composites sock. That really made the fiberglassing easy.

Check out the epoxying video in my Google drive link to see the fiberglassing process. I used a rotisserie motor (borrowed from Howard) to keep the tube rotating while I applied epoxy.

At the end I used a shrink wrap plastic(?) sock (also from Soller) to squeeze all the epoxy as it was drying. That gave the tube a lovely glass finish. However, you need to remove the plastic before the epoxy sets, otherwise, it's a pain to remove.

I also agree with Jim and Curtis on the Soller composites socks. This rocket is 5.5" loc tubbing fiberglass with a single layer of Soller fiberglass. Big Nuke 3E on an M1780 The tubes alone have good structure, and the fiberglass gives it some durability. If you really don't want the cardboard, you will still need a good mandrel to ensure you get the right inner diameter.

The biggest issue I have found around here with L3 motors is having a rocket big enough to stay under the waiver. This one went to 8500ft, and that was with a smaller M motor than the one you are using.