GLUEING AND PAINTING PART 1

Last Devlog

In the last devlog I’ve tested the engine block, only to realize later on that the way I tested them was the main cause of problems.
I’ve redesigned the Engine Block, so that it’s safer and the ejection charge has enough space to go through.

Glueing

I am not actually done glueing all the parts together, as I am still waiting for my epoxy resin to arrive. As of now, I’ve only glued the fins to the body to make the steps later on easier.

You might ask yourself why I won’t just use my normal “everything”-glue..
And the answer is pretty simple actually.
Epoxy is way stronger, and I want to be sure that nothing will rip apart during the flight.

This means, I will use some epoxy on the fins and the engine block.
The nose cone should fit snuggly but I am not going to glue it to the body, as it needs to be loose, for the parachute, which ejects through the top part of the rocket.

Painting it

I’ve tried to keep the design pretty simple. I started by spray painting the whole body black. Then I added the white lines just to make it look kind of interesting. I also added some splashes from a toothbrush dipped in paint, so that it looks like there a little stars on the rocket ^^ ⭐

The Rockets name

It’s called LF-3. LF because it’s flying low and I switched the letters around, because it just seemed more interesting to me.
And 3 because it is not only my lucky number, but the 3rd prototype of my rocket designs.

Recording problems

Sadly, I’ve lost a lot of footage of me for example spray painting the body, cutting the parts etc. because my phone kept disconnecting from the wifi when I was working outside :/
That was about 2 hours of extra footage, that were lost..

WHAT’S NEXT?

Next I’ll be glueing again, assembling the rest of the rocket. I will also make some fire resistant wadding to protect the parachute during ejection :>

ENGINE BLOCK TEST 1 + 2

Well.. uhh

My Engine mount could not withstand the motor’s force -_-

THE FLIGHT COMPUTER

I’ve been working on the electronics and software for the rocket, and honestly.. this part was probably even more annoying than designing the rocket itself 😭

The flight computer is based around an ESP32-CAM, with the camera running separately from the sensors. Core 0 handles the camera and video, while Core 1 handles the MPU-6050, BMP280, flight state and telemetry.

THE FLIGHT COMPUTER

The main idea is pretty simple.
The MPU-6050 measures acceleration and rotation, while the BMP280 measures pressure and therefore altitude. The ESP32 then uses this data to figure out what the rocket is doing.
There are currently different flight states:
IDLE -> ARMED -> BOOST -> COAST -> APOGEE -> DESCENT -> LANDED
So basically, the computer is constantly asking itself:
“WHAT IS THE ROCKET DOING RIGHT NOW??”
The sensor system runs at 100 Hz for the MPU-6050 and 50 Hz for the BMP280, so it should get plenty of data during the flight.

CALIBRATION 💽

And this is where I found one of the bigger problems.
Originally, the computer automatically started a calibration when it booted. It would tell me to keep it still, wait 3 seconds, and then take 500 samples from the MPU-6050.
But that isn’t really what I want.
I don’t want the calibration to happen whenever the ESP32 starts.

I want to put the rocket exactly where I want it, then press a button:
START POS

And that’s it.

The computer takes the current sensor values and uses them as the starting reference.
So the current position becomes the calibrated starting position, and the altitude gets reset to the launch position as well.

This also makes way more sense for the rocket because I can power everything on, put it on the launch rail, make sure everything is positioned correctly and then press the button.
Much better.

LASTLY

The code was horrible to write. I hope that it was worth it in the end, as I really want a video and flight data in the end of the first flight.

Next up is the assembly of the rocket, sanding, painting and glueing, yeah!

Like and Follow ig

PROTOTYPE 3 AND MODELING THE IMPORTANT PARTS

My parts arrived some time ago! But sadly, some of the parts, that I needed were sold out the point I ordered :(

Last Design, WAY TO POWERFUL

When I checked my last rocket, with the inputs of the only motor I could get, I noticed something problematic… I accidently had 1 parameter wrong. The thickness of the cardboard body tube. Thats why it was weighing >1kg. I fixed it, ran a flight simulation again.. AND HOLY MOLY IT CRACKED 300 METERS -> ~984 FEET

And there are legal limits, which is why I redesigned the rocket and ordered smaller C5-7 Motors.

THE NEW DESIGN

It’s perfect. I love it. It looks beatiful. The fins. The Nose cone. Everything. Slimmer, more dynamic and it perfectly hits ~100 meters.
But again.. there is just a slight problem..

Ejection 💥

But sadly, the ejection isn’t perfect, as the parachute ejects 7s after launch. This means, after the rocket reached its apogee, it falls for a certain amount of time and accelerates.
AND IT DOES THIS TO LIKE 100KM/H -> ~62 MPH

That’s why I calculated, if the parachute and shock cord could save the rocket. And yes (hopefully).

Calculation for it

Rocket mass with motor: 0.15kg
Acceleration: 184m/s^2

F =m*a
F = 27.6 N

This means, my shock cord needs to withstand this amount of force, right after the parachute unfolded.

Shock Cords max. weight: 14.5kg
With knots: 14.5*0.5 = 7,25kg

1N ≈ 0.102 kg (102 g)
Thus:
 27.6N = ~2.814 kg

2.814kg < 7.25kg -> therefore, we're good. (as long as the parachute doesn't rip)

3D PARTS

Yes yes, the new parts.
Most of the time I spent thinking and researching about exactly these parts. I did A LOT OF IT not recording. Probably more then 5-10 hours 😭.
But thats what I came up with:

The Motor mount.

The long tube-like part is the motor mount.
It well.. Mounts the motor to the rocket. The rectangle like hole is for using a retainer clip, that I will be making out of a thin aluminium strip. The circular hole (not visible from this side of the image) is for threading through the shock cord, which will be secured using a monkeys-fist knot. The motor is printed out of PETG.

Nose Cone 🔝

I love this part. It’s the tip of the rocket.
Its made up of 2 Parts. Firstly the top part, which has 2 holes, that are both for electronics.
The hole on the side is for a camera and the hole on the bottom is for inserting the electronics into the cone. Its also for attaching:
The bottom plate. It’s secured by 2 long M3 Screws and has a hole as well for securing the shock cord.

Currently, all of the 3D parts are untested.
I’ve only printed test rings to see if they will fit inside the cardboard body tube (now using a thinner tube btw)

Yeah! Thats it for today, please follow my project :D

DEVLOG 3: MY ROCKET IS STABLE NOW (I hope so at least)

It took me a quite some time, but my prototype is finished now.

What changed?

The rocket is way more stable now and a lot smaller than before. Also, I’ve also done proper research for a rocket motor I can use and how to actually build it into the rocket.
It uses a G-Class Motor, which is quite strong. If I didnt use a board computer and made the rocket even smaller, I couldve reached way higher altitudes.
But It is what it is

Stability

As I already said, THE ROCKET IS MORE STABLE.
The goal stability of a rocket this 1-2 calibers.
My rocket has a stability of 1.36 calibers, which is stable enough 😎

Altitude

The rocket reaches an altitude of around 96 meters!!! That’s actually really close the the max limit it is allowed to travel (laws ).
Oh, and in freedom units its like 54,8571428571 Bananas or 300 feet 🦶.

Whats next?

Next, I will need to:
Make the 3D Models of:

• The Centering Rings
• The Fins
• The Nose Cone

Build the Electronics and Code for:

• The Flight Controller
• The Camera

Sew and Calculate:

• The Parachute

AND I ALSO NEED TO WAIT UNTIL 2 MORE PARTS ARE IN STOCK AT ONE OF THE ONLY MODEL ROCKETRY VENDORS IN GERMANY GRRRR

Devlog 2: Rocket designing

Today, I’ve been searching for more fitting parts.
I also used OpenRocket in order to plan the construction of the rocket and to do flight calculations.

I’ve also learned that parachutes are god damn expensive, which is why I’ll probably make my own from nylon fabric.

How did I find this out?

While plotting the calculations for the rocket, there was a spike in acceleration, since the parachute’s diameter was too small. Therefore I needing a bigger parachute.

Yeah!

Other things I might need to do:

• Shorten the body
• Change the Rocket Motor
• learn how to actually fit the motor in with the rings securely
• learn how to secure the nose cone with the shock cord and the deployment of the parachute

Devlog 1: Rocket

Today, I’ve spent most of my time searching for the right parts for the rocket.
I felt that I needed a lot more research, which I’ll be doing without recording. :/

I plan to install a camera in order to record the flights as well as an IMU to measure how far the rocket went.
Maybe even a Piezo, so that the rocket is easier to locate after it landed.

Do you have any other ideas on what to add?
Maybe any tips? :D

Here is an extract image of the partslist that I am working on rn