Polaris - TVC Rocket

So today my 3d printed parts arrived which was awesome, My Body tube had also arrived a while before that so I got to assembling, I first started with the landing mount and assemebled using m3 screws, I used nylon for most of them and heat set inserts but I might switch to steel screws, I used some rubberbands I had lying around and tested wheter it works and it did kinda? there was a weird issue where the whole rocket tilted a little and put all the weight on 3 legs instead of 4, This was probably because of warp in the 3d print probably, I added some blue painter tape to the edges to help with this

Another thing I found was that the landing legs themselves acted as a spring, When you dropped it from a certain height or put enough pressure the leg itself bent. I actually like this accidental design because it helps with softer landings

The TVC mount was where I messed up. I realized that I hadn’t left space for the bottom y axis mount to move the way it should and structurally there were some issues also, to solve this I used a soldering iron to melt at the plastic and created a messy area for it the move and that helped pretty well, I have to redesign this in v2. Besides that I also forgot to tell my printer I needed my avionics bay printed and that I needed 2 tvc rockets not one, so i’ve decided that I’m going to focus more on getting one succesful flight up and parachute or do something like bps space did with echo and drop the rocket from a drone at high altitudue and try to land it (this is probably what im going to do). The rest of my parts are going arrive in the coming week but school also started so progress will be slow.

Today I worked on finalizing the bom, and I tidied up my repo, I added the old firmware I had coded with the flight computer but I’ll have to update it, I also came across this really weird issue with the pcb, last time I placed a fake order just to see the final price it came out to $350, but today somehow its 270? and also my shipping and customs alone are close to $100 which is crazy, I’m going to fix this pcb issue and submit but thats all, I also made a wiring diagram for the launchpad stuff

Edit: So I sent a question in the help channel and I decided that im going to be assembling the pcb my self, this will be much harder but it’s worth it for the cost savings.

Today was working mostly on my landing legs, I first got some inspiration from actual rockets like the falcon 9 and began designing. I first began by modeling the mount that will hold the legs and then worked on actual legs and struts, The main issues was making sure it fit proerly and wouldnt rub against the main ariframe, I made some cutouts in the landing mount to fit the servos, The landing legs will have rubber bands that act as spring and they will be held in the up position with a rubber band, Using a nichrome wire the rubber band will be heated and cut when I need it to deploy. Other than that the final steps will be making the wiring diagram for the launchpad updating github with my code and cad models. I also made a render with gemini that came out suprisingly well.

I did some small work today, I first began by making my own water deluge system, I first made a container that fits under the rocket launch pad and has a small sumersible water pump that pushes water directly under where the motors engine heat will be concentrated, I did this to mainly to lengthen the lifetime of the launchpad because after a certain number of launches this will probably just be too damaged. I also chose the uno r4 edition as my board that will control all my electronics, with this I can control the 2 servos, 2 esp32 cams,5 lights on the launchpad much easier and from a safer distance. I also did some BOM work and figured what parts I would need, I’m hoping this is an x tier project, the flight computer itself is coming out to $230 with shipping so I’ll have to find ways to save costs. The final steps are to make a BOM and finish up the landing legs.

Today was assembly day, I worked on first bringing all the parts together in onshape and I made sure to keep everything organized so its easier in the future for changes, I first began by making the rocket nose and tubing in onshape. I then got a 3d model of my flight controller pcb and made my own avionics bay for it, I made sure to leave space and areas for wiring. After that I began by making the complete assembly, I added the servos to the tvc mount and had to change some dimenions to make sure it fit properly, Then I made a full rocket model, and made sure to add the servos for the control arms on the launchpad. I ran into some dimensions issues but I went back and changed those pretty easily. I then got the lights and cameras in my cad.

I added 2 esp32 camera modules to the launchpad to record everything, I’m not sure if these will be fixed posistions ill probably move them around. I als added some WS2812 Breakout boards around the launchpad, and I also want to recreate the strobing red light effect thats used on the blue origin launchpad before it blew up, I didnt add the rgb strip light to the main strucutre yet and ill have to do that later. But that’s basically it, I’m also planning on adding aluminium protection on the flame trench just 5mm plates, and i’m going to add a small water pump to help out more with cooling. The final steps for this project will be making the BOM, writing the code, and finalizing cad.

Today I mainly focused on the TVC mount, There were many avalible models online and using them as refrence I created this, The mount uses sg90 tower servos, and m3 push rods. For the rocket motor I chose the F15 because it has a bunch of documentation on it and has a very predicatable thrust curve. I first began by modeling the motor mount and added a engine block at the top to prevent the motor from flying into the rocket. I then worked on the x and y axis and made sure that everythign was specced to the right dimensions to decrease slack. Other than that I also did some small work on the open rocket sim but didnt record like usual. The final steps will be to design the landing legs which will proably take the longest and finish up the launch pad, and create a full assembly.

Today I did some basic ground work. I first began by looking at my old flight computer I made this during blueprint but I never got to submitting which I don’t know why I didnt, beside that I added some silkscreen on the front and I’m going to add some on the back. After I began work on my rocket, So the main thing I had to think about was how the first and second motor ignition would work, I saw some examples like how joe barnard did with his scout e rocket but I had a diffrent idea. I split my rocket basically into 2 stages

The first stage has the ascent motor and is connected to the actual main rocket via a coupler, There is also a tvc mount for this stage which is connected to the flight computer via jumper wires. After the ascent motor is burned out the rocket reaches apoggee and starts coming back down and after a set time a pyro charge ignites the 2nd motor this will basically hot burn the first ascent stage off the rocket, To protect the first stage I’m going to add a thin aluminium bulkhead with a layer of some sort of heat insulation, and during the seperation The servo wires for the first stage tvc will just pull apart. I’m still thinking about wheter I will just let the first stage just fall or find a way for a parachute to fit safely, If anybody has some way I could bring it safely down I would love to here it, I’m going to start working on the landing legs soon and I need to work on a small emergency parachute for the first stage incase the motor doesnt light or the legs don’t come out as intended.

This is my first journal entry in what will probably be a really long project, My current plan for this project is to make a tvc rocket that can take off and land by itself, and make a custom launchpad with it. Today I just looked through my old flight computer model I had made and added some silkscreen I also think I’ll probably add a pyro charge to it? I also made rough cad modelling for my launch pad taking inspiration from bps space’s launch pads. I’m going to work a bit more today on the launch pad model and actually make itnto something like a real launchpad.