I've been meaning to look for threads of builds like ours, so thank you for that! We have a lot of design considerations still up in the air, and that thread is a great resource. Thanks.
98mm Min-Diameter Composite Mach 3 Build
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plugger
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Here are some build threads that resulted in successful flights fyi...
Mike P's DDT
Nic L's Mad Max
Mad Max II
Mike P's DDT
Nic L's Mad Max
Mad Max II
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remind me/us...where is this being flown at?
Seems like 3 or 4 places that can handle this type of flight
And who/is there a Mentor/L3 /flier of record yet?
Just asking....
Tony
Seems like 3 or 4 places that can handle this type of flight
And who/is there a Mentor/L3 /flier of record yet?
Just asking....
Tony
We plan to launch at Seymour in April/May.
It's my understanding that @JimJarvis50 is overseeing the project and will be attending our critical design review in December.
One thing about that av-bay co figuration that causes problems is the location of your static port.
When the port is way forward on the nose one, it's angled into the relative wind, causing it to act as a pitot tube, not a static port while the rocket is in motion.
This causes the baro sensor to show an increase in pressure while on ascent, while the accelerometer is in disagreement with that.
Certain altimeters aren't bothered by this, others definitely are. I think the general consensus when I looked into it a while back was anything that uses a Kalman filter would have a bad time.
There are other options, like running accel-only, but that's not ideal either.
Depending on your static port location, if get with Keith and Bdale and see what they have to say about the Megas.
When the port is way forward on the nose one, it's angled into the relative wind, causing it to act as a pitot tube, not a static port while the rocket is in motion.
This causes the baro sensor to show an increase in pressure while on ascent, while the accelerometer is in disagreement with that.
Certain altimeters aren't bothered by this, others definitely are. I think the general consensus when I looked into it a while back was anything that uses a Kalman filter would have a bad time.
There are other options, like running accel-only, but that's not ideal either.
Depending on your static port location, if get with Keith and Bdale and see what they have to say about the Megas.
robopup
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W/r/t the kalman filter, not necessarily. My experience with kalman filtered baro altitude and accelerometer data to determine altitude/velocity/acceleration is that it's been quite resilient to baro oddities due to static port placement and supersonic flight.
I have several flights now with your altimeter-and-static-ports-in-the-nose configuration, all running the kalman filter described above on my homebrew altimeter, and they've all been solid. I don't have plots handy on me atm, but I'll try putting something up later this week comparing accelerometer integrated altitude/raw baro altitude/kalman filtered altitude with the latest 54mm flight I had. For reference, I basically implemented what's in this paper: https://www.google.com/url?sa=t&rct...9d1c19f0.pdf&usg=AOvVaw2Bv9PXvB4JT8GNSV9ittPg
Having said that, I haven't looked very closely at source code from other open source commercial products; I assume their implmentation is similar but YMMV. And I'd never hook up charges first shot without having a solid understanding of what the altimeter is doing and how it will react to a certain placement.
JimJarvis50
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Well, I agreed to attend the design review (for the Mach 3 rocket and for the stabilization system), but I'm not sure I'm overseeing the project just yet. We'll see what happens. By the way, Seymour has a hard 32K limit (according to the person that obtained the waiver). It would be difficult to reach Mach 3 and stay under the waiver with a 4" rocket.
Jim
In the spirit of prototyping, we're going to be making a small-scale version of this rocket. It will be built with all of the exact methods and materials that we plan to use on the real thing. It will likely be either 75mm or 54mm.
Considering this rocket will have roughly the same proportions as its full-size counterpart, what's the best chute method for skinny rockets? I've never built something this high-powered and skinny. I haven't had the best reliability out of chute releases in the past, but are there other clever ways around dual deployment from a single separation?
Considering this rocket will have roughly the same proportions as its full-size counterpart, what's the best chute method for skinny rockets? I've never built something this high-powered and skinny. I haven't had the best reliability out of chute releases in the past, but are there other clever ways around dual deployment from a single separation?
waltr
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Cable cutter?
I'll look into it. Only ever tried my hand with Jolly Logic-style releases. Just this past weekend at our launch we saw multiple rockets' releases tangle up and fail. I assume user error contributes, but we obviously want to maximize our chances of a clean deployment.
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Here are some different cable cutters to look into as well as some release devices.
https://www.tinderrocketry.com/tinder-rocketry
https://aeroconsystems.com/cart/launch-recovery/cable-cutter-by-archetype-rocketry/
Any method that uses a single bay for dual deployment will increase recovery/tangle issues. With whatever method is chosen, lots of planning and testing needs to happen to reduce the chance of flight issues.
https://www.tinderrocketry.com/tinder-rocketry
https://aeroconsystems.com/cart/launch-recovery/cable-cutter-by-archetype-rocketry/
Any method that uses a single bay for dual deployment will increase recovery/tangle issues. With whatever method is chosen, lots of planning and testing needs to happen to reduce the chance of flight issues.
I'm a cable cutter apologist. I would even say that it's your only choice for a rocket like this.
Any of the Tinder cable cutters are very well thought out and reliable. I'm especially a fan of the Mako. Even though it's large, it has some advantages over other cutter that are smaller. I myself would use it for everything 54mm and up.
As Rocketace mentioned, you have to fully think through the deployment sequence. In addition to concerns with tangling, I'd also add strain relief of the E-match lead to the plan.
Here's a picture of my setup from a 54mm minimum diameter rocket. This all fit in the bottom half of the nosecone with the av-bay on the front half. Lots of zip ties for the strain relief.
Any of the Tinder cable cutters are very well thought out and reliable. I'm especially a fan of the Mako. Even though it's large, it has some advantages over other cutter that are smaller. I myself would use it for everything 54mm and up.
As Rocketace mentioned, you have to fully think through the deployment sequence. In addition to concerns with tangling, I'd also add strain relief of the E-match lead to the plan.
Here's a picture of my setup from a 54mm minimum diameter rocket. This all fit in the bottom half of the nosecone with the av-bay on the front half. Lots of zip ties for the strain relief.
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waltr
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I just did first test flight with a cable cutting type of deployment on the main this past Saturday.
It worked perfectly.
What I did is bundle the main and lower cord in Nomex tied to the quick link near the ebay. This keeps the ematch wires from pulling off. Also tied through the nomex eye. This way the pulling between the drouge nd booster is held by the cable tie. The Nomex is secured the the cord a bit below the chute.
Then there is a 9 foot cord to the nose with a drogue 2 foot down from the nose. This keeps the nose and upper cord away from the main. When the cable is cut the the chute is pulled out of the Nomex and lower cord extends allowing the main chute to unfurl away from the drogue.
Drogue size is important to keep the nose and upper cord to the main tight. Drogue should be large enough to do this but small enough so that the nose and booster do not hang together under the drogue. We want the nose and booster to be separated.
Most of the JLCR setups I have sen have no drogue and the cord is not pulled tight. Diring descent I see the nose, cord & booster flopping around. This then allows the main to deploy under the cord or nose and become tangled. By adding a small drogue the upper cord and nose are controlled and are pulling away from the main chute bundle allowing clear air for deployment.
The way the chute and shroud lines at packed is important to prevent tangling. This is another subject.
It worked perfectly.
What I did is bundle the main and lower cord in Nomex tied to the quick link near the ebay. This keeps the ematch wires from pulling off. Also tied through the nomex eye. This way the pulling between the drouge nd booster is held by the cable tie. The Nomex is secured the the cord a bit below the chute.
Then there is a 9 foot cord to the nose with a drogue 2 foot down from the nose. This keeps the nose and upper cord away from the main. When the cable is cut the the chute is pulled out of the Nomex and lower cord extends allowing the main chute to unfurl away from the drogue.
Drogue size is important to keep the nose and upper cord to the main tight. Drogue should be large enough to do this but small enough so that the nose and booster do not hang together under the drogue. We want the nose and booster to be separated.
Most of the JLCR setups I have sen have no drogue and the cord is not pulled tight. Diring descent I see the nose, cord & booster flopping around. This then allows the main to deploy under the cord or nose and become tangled. By adding a small drogue the upper cord and nose are controlled and are pulling away from the main chute bundle allowing clear air for deployment.
The way the chute and shroud lines at packed is important to prevent tangling. This is another subject.
Sorry for the absence of content over the last month and a half. The combination of exams and working on this project was pretty hectic. A lot has changed since my last post, so strap in. I'll do an overview of our current progress.
In early December we hosted a design review and talked through a lot of important decisions with the help of @JimJarvis50 and @robopup , so thank you to them for attending and contributing.
First things first, this project, which we named Echo, was downsized to a 75mm min-diameter to accommodate conventional dual-deployment while maintaining as much velocity as possible. Seymour was also chosen as our launch location in April, and the downsizing Echo was also to remain under the 32,000ft ceiling. We've already mock-packed all of our shock cords and chutes to ensure that we only use as much body tube length as is needed. We'll obviously do plenty of ejection tests once we finish construction.
Here's some data for y'all. Although the general construction was designed in OR, Rasaero has proved very useful for getting more accurate numbers. I'll talk about it too, but a lot of CFD has been done on the fins and nosecone.
The fin design for Echo has been optimized for supersonic flow while maintaining strength and conforming to fin flutter constraints. It uses a clipped delta profile with a symmetric double-diamond cross-section. The core will be constructed out of G10 fiberglass laminate and covered in a carbon fiber tip-to-tip layup.
Mach 2.5 flow over the leading and trailing edge of the fins:
Shock wave visualization of Mach 2.5 flow over the cross-section of the fin:
Force results showing the resulting applied force on the face of the fin, total drag force, and skin-friction drag respectively:
Initially, we wanted the fins to be created from 6061 aluminum alloy. However, aluminum has issues with sticking to epoxy unless it is first treated with a sulfuric acid-dichromate mixture. This issue could be overcome by making the fins out of G10 fiberglass. We ultimately decided to use G10 as it does not have these adhesion issues while also having a high enough rigidity to withstand the expected speeds of our rocket without fin flutter becoming an issue. We used a MATLAB script that utilizes flutter boundary equations, the dimensions of our trapezoidal fins, and aluminum and fiberglass material properties to calculate flutter velocities at different altitudes to determine if fiberglass would be rigid enough to withstand the velocities associated with Echo.
In the interest of reducing material costs, we are in the process of developing our first-ever in-house nose cone. First laying up fiberglass in two individual halves of a 3D-printed mold, the two halves are clamped together and a bladder is inflated to pressurize the interior of the mold and squeeze out excess resin. Once cured, the nose cone is separated from the mold, and excess material is trimmed off, allowing for the precise location of an eventual threaded aluminum tip. We've found success in our first iteration, but we're going to spend time making more prototypes to perfect it.
To be continued...
In early December we hosted a design review and talked through a lot of important decisions with the help of @JimJarvis50 and @robopup , so thank you to them for attending and contributing.
First things first, this project, which we named Echo, was downsized to a 75mm min-diameter to accommodate conventional dual-deployment while maintaining as much velocity as possible. Seymour was also chosen as our launch location in April, and the downsizing Echo was also to remain under the 32,000ft ceiling. We've already mock-packed all of our shock cords and chutes to ensure that we only use as much body tube length as is needed. We'll obviously do plenty of ejection tests once we finish construction.
Here's some data for y'all. Although the general construction was designed in OR, Rasaero has proved very useful for getting more accurate numbers. I'll talk about it too, but a lot of CFD has been done on the fins and nosecone.
The fin design for Echo has been optimized for supersonic flow while maintaining strength and conforming to fin flutter constraints. It uses a clipped delta profile with a symmetric double-diamond cross-section. The core will be constructed out of G10 fiberglass laminate and covered in a carbon fiber tip-to-tip layup.
Mach 2.5 flow over the leading and trailing edge of the fins:
Shock wave visualization of Mach 2.5 flow over the cross-section of the fin:
Force results showing the resulting applied force on the face of the fin, total drag force, and skin-friction drag respectively:
Initially, we wanted the fins to be created from 6061 aluminum alloy. However, aluminum has issues with sticking to epoxy unless it is first treated with a sulfuric acid-dichromate mixture. This issue could be overcome by making the fins out of G10 fiberglass. We ultimately decided to use G10 as it does not have these adhesion issues while also having a high enough rigidity to withstand the expected speeds of our rocket without fin flutter becoming an issue. We used a MATLAB script that utilizes flutter boundary equations, the dimensions of our trapezoidal fins, and aluminum and fiberglass material properties to calculate flutter velocities at different altitudes to determine if fiberglass would be rigid enough to withstand the velocities associated with Echo.
In the interest of reducing material costs, we are in the process of developing our first-ever in-house nose cone. First laying up fiberglass in two individual halves of a 3D-printed mold, the two halves are clamped together and a bladder is inflated to pressurize the interior of the mold and squeeze out excess resin. Once cured, the nose cone is separated from the mold, and excess material is trimmed off, allowing for the precise location of an eventual threaded aluminum tip. We've found success in our first iteration, but we're going to spend time making more prototypes to perfect it.
To be continued...
Some pictures of our nose cone progress. First early 50% scale prototypes. Then our first iteration full-size piece. Compressed mold with the inflated bladder. NC is being removed from the mold. We have a lot more work to do on them before we're confident enough to fly with them. It's been fun learning how to make them though.
Rather than housing an electronics bay in the midsection of the rocket, the core electronics of Echo will reside on a 3D-printed sled in the nose cone. The dual-redundant TeleMega and EasyMega flight computers, as well as the wifi switch and batteries, will all be contained within the nose cone, while also functioning as a retainer for the aluminum tip and recovery system. We had some issues with preliminary design, but we've worked through those issues and have a prototype we're confident in.
I don't have a picture of it, but per @JimJarvis50's guidance, we will run an umbilical from the ebay down to the lower body coupler to two more ejection wells. It will have quick-release clips that separate on ejection.
My favorite part is the body tubes. I've been making a lot of prototypes with different thicknesses and finishes, while also running tests on an Instron machine. Our final body tubes will be 59 and 10 inches long, with an approximate total length of 84 inches. Constructed of six layers of 2x2 twill weave carbon, the body tubes can easily withstand the necessary forces while keeping weight to a minimum.
Echo will be flying on a Cesaroni M2245 IMAX.
That's where this project currently sits. Lots of changes and answered questions but I feel we've overcome a lot of our initial problems. We're hoping to start construction in early January once we secure the right carbon fiber and high-temp resin.
Rather than housing an electronics bay in the midsection of the rocket, the core electronics of Echo will reside on a 3D-printed sled in the nose cone. The dual-redundant TeleMega and EasyMega flight computers, as well as the wifi switch and batteries, will all be contained within the nose cone, while also functioning as a retainer for the aluminum tip and recovery system. We had some issues with preliminary design, but we've worked through those issues and have a prototype we're confident in.
I don't have a picture of it, but per @JimJarvis50's guidance, we will run an umbilical from the ebay down to the lower body coupler to two more ejection wells. It will have quick-release clips that separate on ejection.
My favorite part is the body tubes. I've been making a lot of prototypes with different thicknesses and finishes, while also running tests on an Instron machine. Our final body tubes will be 59 and 10 inches long, with an approximate total length of 84 inches. Constructed of six layers of 2x2 twill weave carbon, the body tubes can easily withstand the necessary forces while keeping weight to a minimum.
Echo will be flying on a Cesaroni M2245 IMAX.
- Total Impulse: 9976.7 Ns (2242.8 lb/s)
- Average Thrust: 2326.4 N (523 lb)
- Maximum Thrust: 3357 N (754.7 lb)
- Burn time: 4.29 seconds
- Dimensions: 75 x 1025 mm (2.95 x 40.35 in)
That's where this project currently sits. Lots of changes and answered questions but I feel we've overcome a lot of our initial problems. We're hoping to start construction in early January once we secure the right carbon fiber and high-temp resin.
Some additional fun facts:
- I got my L2 a while back. Had a "slight" ejection test malfunction the day before but managed to get it fixed and had a clean flight. FYI sparkies look great on cloudy days.
- I have a background in graphic design so I thought it would be fun to make a mission patch for this project. I also got to nerd out about making the angles of the tip and fin shockwaves the exact angle that CFD showed us. I take commissions. Jk. I don't have time for that.
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Which quick clips are you using?
Haven't chosen a specific one yet. Just decided that's the path we want to take. I'm open to suggestions.
I've seen Apogee sell jst connectors, but I've mostly been looking at sae connectors. Jim recommended something specific but I've been unable to find the exact ones.
JimJarvis50
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I don't have a great picture either, but here's what I suggested. These are called Deans micro plugs. I like them because the wires can be soldered to them and the pins can be filed to get the exact separation force that you want. I get them at Hobbytown in north Austin (although they are seldom in stock because I buy them out).
Jim
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Which JST?
https://www.mattmillman.com/info/crimpconnectors/common-jst-connector-types/
I use the RCY style in mine BT70-5.5" builds. But not sure they qualify as they won't come apart easy.
This is coming from the heart....
Less focus on flashy 3D models and "Mission Patches" and more focus on actually learning and flying.
3D models don't show capability, anyone can make pretty pictures and "build the boat in the basement." This is something I am struggling DEEPLY with for the last year trying to hire new (capable) engineers, come interviewees with masters degrees or several years of experiences at the time of interview. Models don't get the job done. Real engineering drawings of what you are doing, how you want it done, how you anticipate it getting done, a means of telling your audience what you are doing and why, communicating via drawings, in a manner that is clear and concise, and depicted in a manner that is not confusing to the reader, etc. These are what gets the job done and provides continuity of design for a project.
If someone sits down across from me during an initial interview and all they have to show is print outs of 3D models, the interview is not going to go very far. If someone sits down across from me and shows me a 3D model of an idea (doesn't even need to be good!), and then the engineering drawings, the doc's that outline the project or idea, a thought model of some sort, a flow diagram on how to build what they are showing, etc. Drawings that follow real drafting and design standards, dimensions and tolerances that are actually realistic for the prescribed manufacturing process, an understanding of the manufacturing process(es) that the designer intends the maker to follow; yes, that is the engineers job, not the poor guy who has to figure out how to make it. It is not a machinists job to be the engineer. This interview will go a lot longer and be far more interactive because all of these documents show their ability to not just make pretty pictures.
One of an engineer or designers most important jobs is to convey their intended outcome without words, but with drawings and details. If someone cannot do that, then they are not meeting the bare minimum for designing and engineering products.
I hope in your design review, you have provided at least some of these. I also hope that those who have done the design review, have expected and been provided with the bare minimum and in a fashion similar to what I have outlined above.
I am begging, hoping, and praying, for good and competent engineers coming into the job market. We need them badly because what we are being provided with fresh out of college, based on the 24 interviews I have done in the last 14mo, is not cutting it.
This project is great, and is one like many others before it. Do yourself a service and do a REALLY good job on not just your ideas and 'visual arts', but more so how you convey those ideas to the outside world. How you convey those ideas is far far FAR more important.
Less focus on flashy 3D models and "Mission Patches" and more focus on actually learning and flying.
3D models don't show capability, anyone can make pretty pictures and "build the boat in the basement." This is something I am struggling DEEPLY with for the last year trying to hire new (capable) engineers, come interviewees with masters degrees or several years of experiences at the time of interview. Models don't get the job done. Real engineering drawings of what you are doing, how you want it done, how you anticipate it getting done, a means of telling your audience what you are doing and why, communicating via drawings, in a manner that is clear and concise, and depicted in a manner that is not confusing to the reader, etc. These are what gets the job done and provides continuity of design for a project.
If someone sits down across from me during an initial interview and all they have to show is print outs of 3D models, the interview is not going to go very far. If someone sits down across from me and shows me a 3D model of an idea (doesn't even need to be good!), and then the engineering drawings, the doc's that outline the project or idea, a thought model of some sort, a flow diagram on how to build what they are showing, etc. Drawings that follow real drafting and design standards, dimensions and tolerances that are actually realistic for the prescribed manufacturing process, an understanding of the manufacturing process(es) that the designer intends the maker to follow; yes, that is the engineers job, not the poor guy who has to figure out how to make it. It is not a machinists job to be the engineer. This interview will go a lot longer and be far more interactive because all of these documents show their ability to not just make pretty pictures.
One of an engineer or designers most important jobs is to convey their intended outcome without words, but with drawings and details. If someone cannot do that, then they are not meeting the bare minimum for designing and engineering products.
I hope in your design review, you have provided at least some of these. I also hope that those who have done the design review, have expected and been provided with the bare minimum and in a fashion similar to what I have outlined above.
I am begging, hoping, and praying, for good and competent engineers coming into the job market. We need them badly because what we are being provided with fresh out of college, based on the 24 interviews I have done in the last 14mo, is not cutting it.
This project is great, and is one like many others before it. Do yourself a service and do a REALLY good job on not just your ideas and 'visual arts', but more so how you convey those ideas to the outside world. How you convey those ideas is far far FAR more important.
I'll look into them and see what we have laying around our shop. I think we have something similar to the micro plugs that Jim uses.
I appreciate the advice. Your concerns are valid and I'll make an effort to go into more detail about our build in the future. I've largely been sharing brief summaries, but if more niche details are desired I can go that route.
That being said, we don't have a need for detailed drawings to send our parts to get machined. CAD files for 3D printing are sufficient. More importantly, we utilize them in CFD simulations to aid our own learning and design philosophy. Everything we do is in-house, and these "fancy" models I'm sharing are purely to help people visualize what we're working towards. They serve as placeholders until I'm able to show off material progress.
Again, this is all just for fun. I don't spend my time covering every minute detail of what I work on in this thread, but I can include more in the future. I understand where you're coming from and value your input, but I'm going to enjoy this project regardless. If I want to spend a few hours of my break drawing up designs just for the hell of it, that shouldn't be anyone else's concern.
robopup
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While I agree with a lot of your observations, he's a college freshman; let's not nail him to the cross just yet... This is a forum for rocket hobbyists (and that's not a pejorative, I regularly see more technical prowess here than I encounter in my fancy pants engineering job). Full design packages are not a prerequisite for posting a great build thread and I for one certainly communicate differently here than I do in a professional setting.
Some of the arc of this thread has demonstrated a lack of practical experience but a lot of the intent, progress and technical problem solving described in Landon's posts has actually been quite clear, at least to me.
What is the peak acceleration expected during the flight please? That will help guide you on connector selection and other design details.
user 30299
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Both you and StrueB1 have good points.
Some of us are from the days before 3D CAD, even before 2D CAD. We were trained to make & take a stack of 2D drawings and
recreate them in our head as a 3D drawing/model. Or start with an image in our head and set it to paper in 2D. 2D drawings are
still a necessity in many design and manufacturing operations.
Properly drawn prints are an important part of equipment assembly, especially if it's complicated machinery going together
in the field. No, tablets have not replaced prints in the field. I've been waiting for that the last 20+ years.
The creation of proper 2D drawing has a knack of pointing out fit, manufacturing and assembly issues. I recently
put a university team leader through this on a rocket design. The 3D model was awesome looking but the 2D drawing
exercise brought to light some design issues. A 3D interference fit does not mean you have a workable design.
Below is one of my 2D drawings for a rocket. Even though I can design in 3D, I still find the 2D method keeps
my design & build skills sharp. The machinists in the shop, or the installers in the field, look for clear and pertinent
information on a drawing. Nothing more.
Please keep up your postings. I thinks it admirable that you made the effort to do this.
You're asking all the right questions. And we all learn new things from the answers.
Rschub
Well-Known Member
If you're expecting universities to spit out fully qualified engineers that can be trusted to run a moderately complex project with little to no supervision, you might be expecting too much. This is not anyone's fault.
I worked up through the machine shops, to lead CAD designer, to project manager. With several different companies. Along the way I have seen everything from full on CAD/CAM to rows of blueprint books with every product ever made.
Every generation has the responsibility to pass along the knowledge they have gained, so that the next can build on it. The challenge is to know what is true knowledge and what is merely tradition, or better said, nostalgia.
The tools we use are just that, tools. Think about how you learn, you start from your existing knowledge base and expand out from there.
The "non boomer" generations have used computers from birth, they understand them in ways you or I never will.
The world of actual physical parts is unfamiliar territory. Sure, they may have had Lego's or an inventors toy set, but did they ever build a treehouse, or struggle with starting a u-control glowplug engine, or take the motor out or their car and put it back in over the weekend, just to see if they could?
I certainly don't consider myself an expert, I think that's a prerequisite for learning. I would not trust younger me to do some of the things that current me is doing. Older me would not do some of the things that younger me actually did, so it goes both ways.
I find personally that one of the things I struggle with when teaching is the "experts eye" which is seeing things that are second nature to me that someone else could never reasonably know. There is a reason engineering is considered an art. A willingness to learn is all that is really required. Oh, and someone willing to teach.
I think it is great that these students have found this forum and are wise enough to put their thoughts out there for review, with all that entails.
When replying I think we should keep in mind that we in a small way through the knowledge we share, have the key to their dreams.
I worked up through the machine shops, to lead CAD designer, to project manager. With several different companies. Along the way I have seen everything from full on CAD/CAM to rows of blueprint books with every product ever made.
Every generation has the responsibility to pass along the knowledge they have gained, so that the next can build on it. The challenge is to know what is true knowledge and what is merely tradition, or better said, nostalgia.
The tools we use are just that, tools. Think about how you learn, you start from your existing knowledge base and expand out from there.
The "non boomer" generations have used computers from birth, they understand them in ways you or I never will.
The world of actual physical parts is unfamiliar territory. Sure, they may have had Lego's or an inventors toy set, but did they ever build a treehouse, or struggle with starting a u-control glowplug engine, or take the motor out or their car and put it back in over the weekend, just to see if they could?
I certainly don't consider myself an expert, I think that's a prerequisite for learning. I would not trust younger me to do some of the things that current me is doing. Older me would not do some of the things that younger me actually did, so it goes both ways.
I find personally that one of the things I struggle with when teaching is the "experts eye" which is seeing things that are second nature to me that someone else could never reasonably know. There is a reason engineering is considered an art. A willingness to learn is all that is really required. Oh, and someone willing to teach.
I think it is great that these students have found this forum and are wise enough to put their thoughts out there for review, with all that entails.
When replying I think we should keep in mind that we in a small way through the knowledge we share, have the key to their dreams.
My best estimate (from Rasaero) is a peak acceleration of 1115 ft/sec^2 about three seconds into flight, just before burnout.
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Thanks for the number. That's about 35 gees. Remember when designing the rocket that anything onboard will "weigh" 35 times more than it normally does, and the forces exerted by it will be similarly increased. Any unsupported lengths of wire, or other items can put additional strain on mounting points.
There is one point of failure that has been seen in the past for high-G flights, and that is the antenna of the GNSS receiver coming off. It is only held onto the TeleMega PCB by one solder joint and some double-sided tape around the outer edge of the ceramic. Some people, me included, run a small bead of epoxy around the outside of the antenna to glue it to the PCB. You might consider doing the same. It only needs to be about a millimeter high at most.
Regarding connectors, you might want to consider the Molex Micro-Fit 3.0 series of connectors. Compact and lightweight, positive locking, good electrical specs and reasonably priced.
https://www.molex.com/molex/products/family/microfit_30Available at Digikey.
I'm guessing you don't want to pay $400 for the Molex crimp tool, so here is one that does quite a good job on those connectors:
https://www.ebay.com/itm/162343868130?hash=item25cc72d6e2:g:OvEAAOSwo4pYay3IIt also works on many the JST connectors.
I just happen to have the crimper. You could always send them to me to assemble.
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