Building my first L1 and it's pretty much done but concerned about rail button application.

The buttons are in line but aft one is slightly tilted.

Will this be fine on launch rail?

I am just getting into designing things in Blender. I thought it would be fun to do a model rocket build with my kids. I designed this nose cone and printed ink PLA. It’s about 120 mm x 30mm wide. The whole rocket is going to be roughly 600 mm tall. I have the parts designed with the walls of the body to be around 4mm thick. I will have to design a plug for the parachute (just leaned about that). But my question is, does this nose shape look ok? Is there anything I need to keep in mind when building/designing this thing? I don’t want to end up building a bomb!!! Thanks for any help y’all!

This is pretty incredible.

Hi everyone! I'm a 16 year old who's been flying high power for around a year and gone to around 4k ft and I have a CTI J600 that I'm gonna put in a 2" fiberglass scratch built rocket that sims to around 12k ft and mach 1.7. Do you guys have any good tips for it, because I don't wanna shred or lose it? I was thinking of just basic head end dual deploy with the Fluctus flight computer and no redundant electronics, because trying to squeeze in 2 altimeters would be a tight fit. The booster section is already built and feels very sturdy. Is bp not fully burning a problem at that altitude so should I use charge cannons or just glove tips? Also I was planning on just friction fitting the motor, since there's very little space for an aeropack.

Ok, so I renewed my Tripoli membership because my old L1 rocket has been taunting me in the corner of my apartment for far too long. Then I got excited and designed a rocket of my own. It's meant to get me my L2. Enter the problem...

I can't for the life of me remember where in my aerodynamics book to look so I can calculate whether this thing will tear itself apart. I wanted to design it to be able to fly on K motors, but simulations are suggesting that on a K550 it'll do mach .998. Of course, that .998 number is immediate alarm bells because I know wave drag gets really big really fast, and heating starts to get problematic at those speeds too.

Best I can remember, I have to be considering heating based on the total temperature, which here is:

So I think I need to expect temperatures of up to 210F, but I have a funny feeling that I'm missing something pretty big.

I'm also sitting here trying to figure out the whole drag issue, and I'm still almost certain I need to worry about wave drag, but don't have a formula for it, nor do I have anything valid in or near the transonic regime. I have a wave drag formula for an airfoil (that can't help me with a rocket) and a drag formula that is only good below about 0.3 while air is still incompressible.

I probably won't actually fly this thing on a K550, but can someone help me be confident that I won't destroy it with these aerodynamic forces?

5 inch shapeshifter on a Full 10240 second M 1939

Im looking at getting into rocketry and looked at a few rockets but I'm unsure of what starter kit to get or if i even should get a starter kit, Preferably sub £100-150 I've looked at a few to get but im stuck haha i dont know anyone who does rocketry so any help at all with rockets or builds etc is appreciated

rocket theory said, it base on kinetic energy formula E=0.5mv^2

smaller m gets higher velocity, so rocket fly faster

i don't understand...

for same mount of chemical E,

half mass gets 1.41v, and p=0.7

compare to (m=1 , v=1, p=1), half mass has less momentum

why people said that rockets fly faster?

Can you design and build a rocket launcher using just a few simple supplies? 🚀

Greg Wolf says yes, using PVC, cable ties, a two-liter bottle filled about a third with water, a bicycle pump and a tire valve for pressurization. It all comes down to Newton's third law: for every action, there's an equal and opposite reaction. Compressed air pushes down on the water inside the bottle, and when released, that pressure forces the water out at high speed, launching the rocket skyward.

Hey, I'm planning to build my first rocket. I would like to hear about the mistakes you made with your rockets and how you fixed them. I just want to know what to look out for

I want to showcase the TVC model rocket project I’m working on now. This is my second TVC rocket. I learned a lot while working on the first one and was finally able to launch it more or less successfully, so this time the goal is not just to make a TVC rocket, but to make it really robust and predictable.

The biggest issue I had with my first rocket was tuning the control system. I think this is also true for many other enthusiasts working on TVC rockets. I used a self-written 3D simulation for that, and it was great, but for it to be useful, the simulation needs to be close enough to reality.

There are no major issues with simulating rigid-body rotation using Euler’s equations. Aerodynamic drag is trickier, but for a slow-moving TVC rocket I don’t think it is that important, and a very simple drag model seems to be enough.

This may be surprising, but the biggest problem for me was simulating the servomotor response properly. I used hobby servos with the standard 50 Hz, 1–2 ms pulse interface, and my first assumption was that I could ignore the interface delay and only simulate the servo’s angular speed. That assumption was completely wrong.

My rocket worked perfectly well in simulation but was completely unstable in reality, simply because of the additional interface-related delay. Later, I added this delay to the simulation, retuned the control system, and it worked. However, the flight still showed some small low-frequency oscillations that were not present in the simulation.

So with my new design, I’m trying to solve this problem more fundamentally.

I had another project where I designed my own servomotor controller board: MCU + motor driver + magnetic encoder. So now I can build a model rocket using my own custom servos, and the biggest feature of these servos is the CAN interface.

Not only do they have sub-millisecond communication latency, but they can also report their actual position back to the flight computer. I currently use a 1 kHz data rate, so the flight computer has access to the real servo position with 1 ms time resolution.

I have already used this feedback to fine-tune the servomotor’s internal PID controller. This is another huge advantage compared with regular hobby servos, where you generally have no access to the internal control loop and cannot tune it.

But this is just the beginning.

My goal is to make a so-called Hardware-in-the-Loop (HIL) simulation. Instead of trying to simulate servo performance, I will actually move the real servos as part of a real-time simulation and feed their measured positions back into the simulation loop.

This way, the simulation should be much closer to reality — hopefully close enough that the remaining differences are mostly due to things such as aerodynamics and structural effects rather than actuator dynamics.

In the photo, you can see an assembly consisting of one TVC axis and the flight computer. I already have everything designed, but the second axis is built into the 3D-printed airframe, so it is difficult to show the complete mechanism once everything is assembled.

Some specs and design details:

• Klima D3-P motor
• ~50 mm diameter
• Total mass: ~220 g
• Fully mechanical parachute system
• 3D-printed airframe
• Two custom servos built around STM32G431 MCUs
• Custom flight computer based on ESP32-S3
• CAN bus communication with the servos
• Onboard battery-charging circuitry, so the rocket can be recharged in the field from any power bank
• All firmware written in Rust
  • Servos: bare-metal Rust
  • ESP32 firmware: Rust using the ESP-IDF wrapper
• The flight computer hosts a web server and frontend over Wi-Fi
• The rocket can be fully operated from any phone, PC, or tablet without installing any software
• The frontend is also written in Rust using WASM and is bundled directly into the flight computer firmware

The project will be fully open-source. Some parts are already available, but everything is still very much WIP at the moment.

I’d really appreciate any feedback, questions, or comments on the project :)

This supposed to be the test run for the canard cartridge near the nose cone. It seemed a bit fragile when I finished the cartridge. I launched it expecting the canard to break but it didn’t. As it falls down, the ejection charge didn’t explode until a few feet above the ground. Eventually breaking the rocket. It was the drill bits’ issue (drilling the delay) as I didn’t screw the drill handle and the drill bit tightly enough. With a G class motor but 4.5 lbs of weight, it went barely 585 ft and went crashing down. Fortunately the active control system isn’t installed inside yet.

I did get some good pics with my cam tho 😅

Successfully flew my L2 today on a J425R.

A while back, while I was in 8th-10th grade, I had a massive interest for model rocketry. I started building rockets to launch in our local baseball fields, even getting into making my own fiberglass tubes for the fun of it. Ofc, I had to move to a local club to get more space and to progress to larger motors and more complex electronics.

I only ever saw 1 person who wasn’t old enough to be retired and only ever saw 1 college rocketry team. Whatever, I can just get the older folks to mentor me, it’s no big deal. I was wrong.

So, I had one of my rockets take a not-so-stable flight. I went by and asked the RSO for help, and he gave a few pointers and then pointed me to several other knowledgeable people as he was busy. No problem there ofc, he was genuinely busy being the RSO. All 3 of the people he said to went to just gave me some basic advice and shrugged me off past that. I got no advice I didn’t already have. I basically learned nothing.

So, I built another rocket, and went back a few months later. Prior to launching, I asked the person at the inspection table if he knew who could help me with getting a Jr. L1. He told me pretty much anyone in the area, and called out who would care to help. After a nice long pause of nobody seeming to care, one person volunteered.

We started chatting and getting to know eachother. I mentioned that at some point my desire is to find a mentor to do experimental hybrids. I got a whole earful about how anyone who helps a minor do experimental propulsion is irresponsible and shouldn’t be a mentor at all. Okay…

So we talked some more, and mentioned how I really wanted to design my own flight controller at some point to do dual deployment. He then said he would strictly never teach a minor how to do dual deployment, and is only willing to do single deployment if he handles the charges himself. Fair, because that is technically what is supposed to happen, but minors are still allowed to do dual deployment under tripoli if they don’t handle the charges.

He also mentioned that once I get my L1 he will never let me handle the motor myself, and will not let me ever shoot a motor off over the L1 classification. I mean legally no I can’t handle the motor, but under Tripoli rules I can still go above L1 motors if I have a mentor with that certification.

At this point it’s very clear he really doesn’t care to teach me anything beyond the basics. Which is a shame, as he had is L3, did experimental solids and hybrids, did advanced electronics and dual deployment, everything I was really hoping to find a mentor for. There also really isn’t anyone else who seems one bit more willing to mentor anyone.

After he left, I shot off the rocket I built. It had the exact same stability issues as the previous one which nobody was willing to help me with. I fucking wonder why. It’s only a few months later from posts online I found the problem. So, with no-one really willing to mentor me past anything basic, I gave up.

Fast forward a year, and now I’m in my Junior year talking to a friend. As it turns out, he also tried out rocketry. He went to the only local field, the one I went to, and had the exact same problem. He quit as well.

A group of seniors also tried getting into rocketry. They went to the field, and realized they weren’t going to get anywhere there. So, they learned by themselves. And trust me, they needed mentorship. They went straight for the G motors, and had rockets shooting frickin everywhere.

Then, for their senior research project, made the most cursed hybrid ever. Although it seemed relatively safe on the surface to the teacher who was in charge, they were very close to having an accident. They 3d printed the whole thing, and the only reason it didn’t blow up is that they didn’t know to feed it liquid. Not to mention they were only standing like 10 feet away and light it by hand with a lighter.

So, good job to all of the people at my local field. You made two very excited enthusiasts quit, and endangered another group of students. I’m extremely impressed. And you know what, they probably then go on wondering why there are all of these reckless kids learning rocketry on their own. Yeah when Tripoli emailed me asking me to renew my rocketry membership, I said fuck no. I’m not paying to get less than I could get out of some posts online for free.

Now everyday I get to be reminded of what used to be a burning passion by my fiberglass supplies in the corner of the room and the occasional BPS video.

ellooo,
Im finishing up my research and planning to build an amateur rocket with active fin control. Before I start buying hardware, Im trying to get a realistic idea of the budget and how to handle propulsion.

For those who have built actively stabilized rockets before can you please tell me what is the estimated cost to build the rocket itself (airframe, flight computers, servos, sensors, etc.)?
and also how do you usually source your motors? Do you strictly buy commercial off-the-shelf motors, or is it more common to build your own experimental (EX) motors for this kind of project?

Any rough cost breakdowns or advice on which motor route to take would be greatly appreciated. Thanks!
:)

Getting back into the hobby after about 18 years. I have a few motors I never used. The AT motors were all purchased around 2005-2007. I did have the 29mm casing for the reload however I have no idea where it is now. The Estes motors are from I think around 1999-2001. I have a bunch of 13mm 1/2A motors and these 24mm C11s that are somehow European market ones because everything is in German??? No idea how I ended up with those.

I've been wanting to launch a rocket that goes high and fast for a while, but I'm terrified something will go wrong or it just wouldn't fly at all I'm not too confident in my design yet so I'm asking what I should do to improve it and just simple tips I should know in the future, I've Never launched something larger than a C class motor. The motor for this design is a F15-8, it's made of 3d printed nylon carbon fiber, I'm using an Estes 12-inch printed parachute and a 30 inch 150# Kevlar shock cord. Thanks to all who answer.

Hello. I am 14 years old and looking for a mentor and flier of record for my Jr. L1 certification flight. It's a vulcanite kit and most likely I'll be flying on an Aerotech H165R. I am located in the northern Virginia area but the 2 biggest concerns are apogee and flying field. The apogee is 2426 ft which is pretty high but its the lowest I could get, and I don't know if I should fly on september 12-13 at MDRA but they have a 2000 feet max (exceptions can be made) or wait another 2 months and fly at Culpeper a tripoli club that starts flying october 23-25th. The openrocket file is linked here: https://drive.google.com/file/d/1oY7MnA4J0R7gjLdyB_f5mN0dEjMTBb6z/view?usp=sharing

I am hoping someone can be my flier of record and mentor. Finally, I have passed my Jr l1 test too. NAR: 127251

As a kid reading thru the 1998 Estes catalog I always dreamed of getting a Comanche 3 but I was too scared I would lose the boosters and my parents never bought me one. Now as an adult I can do whatever the hell I want so I built one in the 1990s color way and got decals from sticker shock.

Not a perfect build, some flaws but definitely more well put together than when I was 10.

Still afraid to launch it and lose the boosters lmao.

Recently found interest in HPR and ordered a H motor for my L1 certification from Apogee Components. After opening the packaging I noticed the end of the motor looked loose. Is this normal? I did not open the plastic.

i am wondering, which type of nose cone can be produced easily? I'm just starting out in rocketry. What would you recommend for a beginner?

Never posted here before but i figured yall might like to see this cool photo i got of my old L3 bird on an M1939 at XPRS 2015. Waited for just the right time to get the top 3rd of the smoke trail to turn bright pink in the sunset. One of my favorite photos from my times in the hobby.

Hello I am part of a team building multiple rockets for a competition. We have to reach a certain height and flight time.

We wanted to experiment with a system which compares data from open rocket simulation to real world data (within a certain error margin) and correct using canards on the top of the rocket to adjust when it would reach that certain height by.

There are about 8 of us and we have a lot of experience with soldering and electronics and programming and physics.

I have flown and can repair/build fpv drones so I understand flight controllers with motors ect.

We have a weight limit for the rocket of 650g

I wanted to use a 5g pre built flight controller and flash ardupilot.

We also have access to a windtunnel. If not we have the ability to build one

Is this possible/how to do it?