I might just leave it in the airframe when I'm not working on it.That case is a bugger to store isn't it?
Mine is larger than some of the rockets standing next to it in the corner
Hypersonic, I looked on the Composite Envisions website for spread tow fabric & there were quite a few choices. Could you post a link to the one you used on Pepe? Thanks.I will never go back to anything else besides spread tow fabric from Composite Envisions, as this stuff will not fray, and is easier to work with. I can cut any pattern I want very easy. I'm not an engineer either, but I don't always have to prove things by the numbers, as experience will go a long way. And if I don't have very much experience in something, then I play with it to gain the experience that I need.
Wait, you casually mention an O motor? Is this the first you've mentioned your L3 project? This sounds very significant, we need more information! Is it L3 thread time yet?Yep, there it sits. It'll be used for the 2nd flight of my L3 project. I'll fly for Level 3 on some Red Lightning M or N, and the end goal is to fly it on the O3400 like Nick@Jet's Ultimate QCC Explorer.
OK, I will wait until you are ready to unveil your L3 project to us.
Hi Greg,Hypersonic, I looked on the Composite Envisions website for spread tow fabric & there were quite a few choices. Could you post a link to the one you used on Pepe? Thanks.
Htpersonic, thanks. I'm grinding/polishing/figuring an 18" telescope mirror and I want to put it on a Dobsonian truss tube mount. I hope to build the mount out of foam/carbon fiber layups to keep the weight down. Not looking for speed, just trying to gather some info.Hi Greg,
Sure I'll tell you what I used. Like you said, there are many choices of the TeXtreme spread tow fabric available. The one I used may or may not be the best choice for your needs. By doing just a little bit of research (google) you will learn more about tow size, weight (thickness of fabric) modulus (Intermediate, high, or high strength) The price will vary accordingly. I did this research about a year ago, when I bought mine, and I don't remember everything I read. So I don't want to lead you in the wrong direction by misquoting something. This is what I chose to use (remember my application is for breaking speed limits!)
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By making my own plate, or tip to tip, I'm able to use the epoxy of my choice (high temp) along with my choice of fabric, rotating the tows every layer. I agree that my homemade stuff is not made with as much pressure during construction as maybe the Dragon Plate is. Look at the price for 3/16" Quasi-Isotropic high temp CF sheets. I just make mine a little thicker with more layers. Mine is rotated every 45 degrees instead of 90. Will any of this matter? We will see when launch day arrives and its time to light a real fire under PePe. I will be holding my breath with my fingers crossed!!I've purchased C.F. plates from various sources over the years, but there are a couple Amazon sellers that have good products for reasonable prices:
carbon fiber plate
It's not easy to get similar results yourself and I don't think cost effective either.
As far as how much and what kind of joint reinforcement, that's one of those "feel" things that we haven't been able to quantify yet. Theoretically, we should be able to calculate all the forces and the strength of the materials, but we don't have the relevant data and at least I don't have the mechanical engineering knowledge.
FWIW, I've seen 1-3 layers of weave (plain or twill) used for joint reinforcement. I personally have never used more than 1.
Even with engineering knowledge composite structure design is no walk in the park. With basic mechanics materials you have like Mohr’s circle. With composites in advanced mechanics which is like an “optional elective for 4 yr mech students” this Mohr’s circle has stresses in like 9 freaking directions. And throw basic algebra equation out the window they wanted tactic of Elementary Linear Algebra which wasn’t Y=Mx+b slope of line and more like matrices of numerical values and matrix ops (More math or just start using excel spreadsheets.) These along with compressible gas dynamics were more hardcore mech electives for seniors at end of graduating. Some profs joked welcome to the grad course undergrads... I enjoyed compressible flow much more than this composite design stuff.Theoretically, we should be able to calculate all the forces and the strength of the materials, but we don't have the relevant data and at least I don't have the mechanical engineering knowledge.
Yes, this can be done fairly easily with the tools you already have at your disposal, i.e. OpenRocket or RockSim and a spreadsheet. I can point you in the right direction if you're interested but I won't derail this thread with it. Just be confident that most of your intuition, experience, and tribal knowledge are really good enough to cover the vast majority of this hobby.... Theoretically, we should be able to calculate all the forces and the strength of the materials, but we don't have the relevant data and at least I don't have the mechanical engineering knowledge..
That part is true. Everything that follows that sentence is just asinine gibberish.Even with engineering knowledge composite structure design is no walk in the park.
Please keep in mind that Andrew is the kid who zip tied a bunch of electronics to a sled and called it good. Among other construction atrocities.
Moving on, I think the issue with doing any meaningful analysis is the variation of technique and ability. In the absence of ovens and autoclaves, emperical evidence rules. Not mechanical engineering, but mechanical imagination. You can throw all the math you want at it you want, but none of it will apply if your technique is bad.
So Hypersonic, you're definitely not a kindergartner playing with tinker toys. Your technique is sound. You've got a rocket that probably really can go Mach 3 that's also a work of art.
As far as centering the nose tip in the rocket, others have made jigs that held everything straight with tip centered. Jim Jarvis also has a pretty novel method for squaring the ends of tubes. He also does a pretty good job of emphasising the importance of square tubes, if I remember correctly. I'll try and find some examples in the morning. I've got them all saved somewhere.
Thanks HyperSonic. Looks like it's been over three years since the links were posted, so here is one set of them (for Part 1 and Part 2). The laser level method is in Part 2, and it's still how I do it.If you find some of Jim's stuff, point me in the right direction so I can reread them. I always loved the look of his TooCarbYen! And Thank You again.
Thank You Jim!Thanks HyperSonic. Looks like it's been over three years since the links were posted, so here is one set of them (for Part 1 and Part 2). The laser level method is in Part 2, and it's still how I do it.
The high altitude BP method is attached. The only thing I would add to that method is to put the ematch on top of the powder instead of underneath of it. That helps for larger charges. Also, look for Tony's version of this method.