Scratch-built flight vehicle · Rev 2
Single-print airframe / RP2040 avionics / live downlink
Overview
A second-generation airframe keeping the same avionics as Mark-I, but with a much lighter monolithic frame.
Mark-II keeps the flight and ground electronics that were proven on Mark-I and rebuilds everything structural around them. The body, fins, nose cone, base adapter, motor mount and ground-station enclosure are all printed in-house. The only part not made from scratch is the motor.
The headline change is the airframe: fins are now printed as part of the body instead of being glued on afterwards. That removes every fin joint as a failure mode and takes roughly 40 g and 50 mm out of the vehicle.
Vehicle · Side elevation
Six assemblies, nose to tail. Scroll to walk the stack.
01 / Nose fairing
A printed ogive cone in white PLA. It is hollow and carries the entire flight computer, so the nose is both the aerodynamic surface and the payload bay. Printed in one piece with no infill in the shoulder, it stays light enough that the vehicle's balance point sits well ahead of the fins.
02 / Payload
Carried over unchanged from Mark-I: an RP2040 microcontroller with a barometer, altimeter, gyro and GPS, on a single LiPo cell. It samples the flight, drives the ejection event and streams every reading down the wireless link in real time — nothing depends on recovering the vehicle to get the data.
03 / Base adapter
The nose sits on a flexible TPU adapter that plugs into the body tube. Printing it in TPU instead of a rigid plastic gives the joint a friction fit that holds under boost, lets go cleanly at ejection, and survives being landed on. It is also the anchor point for the shock cord — the nose, parachute and body stay tied together as one.
04 / Recovery
A hand-cut parachute roughly 15 inches across, made from garbage bag liner and shroud lines, packed into the forward body tube above the motor. The ejection charge pushes the payload and parachute out through the nose; the elastic shock cord takes the shock so the airframe doesn't.
05 / Airframe
The biggest change over Mark-I. The fins are no longer separate parts glued to the tube — they are printed as part of the body, so there is no adhesive, no fillet, and no fin-joint failure mode. Removing that hardware and tightening the layout took roughly 40 g off the vehicle and 50 mm off its length.
06 / Motor mount
A small copper tab is set into the base, bent in just far enough to catch the motor and no further — it holds the casing without sitting in the path of the burn. That closes a gap found in earlier flight testing: at ejection, the same pressure that pushes the payload and parachute forward can push the motor straight out the back instead.
Hardware
White PLA cone, blue TPU base adapter, shock cord and shroud lines. Shown apart and integrated — with the flight computer inside, the whole nose lifts away as one unit at ejection and comes down under the parachute.
An RP2040 carrying barometer, altimeter, gyro and GPS, wrapped in Kapton and flown on a single LiPo. This is Mark-I hardware, unchanged — the point of Mark-II was to improve the structure around a known-good avionics stack, not to debug two things at once.
Black PLA. The fins come off the printer attached to the body — no gluing, no alignment jig, no added mass at the joint. Mark-I needed each fin bonded on after the fact, which is where both the weight and the length went.
The one place copper shows up. A small tab set into the base bends in just enough to catch the motor and hold it there, while staying out of the way of the burn. Ejection pressure can then only go forward, into the payload and parachute. The motor is the single component on this vehicle that wasn't made in house.
Ground segment
The receiver is Mark-I electronics in a new printed grey enclosure: a flat, low box with a moulded-in antenna mast and a single USB port to the laptop. It sits on the ground at the pad, holds the link through the whole flight, and hands every packet to the ground station software.
Ground software
Custom ground monitoring software. It listens to the wireless downlink, draws the vehicle's position on 3D terrain, and writes every packet to a launch log — the whole flight path plus altitude, pressure, GPS and link metrics, as received.
.log that can be reloaded and re-flown afterwards.Flight test
Mark-II footage goes here as it is flown — pad camera, onboard telemetry replay, and recovery.
Drop clips into assets/video/ and add them to the FLIGHTS list at the bottom of index.html — each entry becomes a player in this grid.
Revision
| Item | Mark-I | Mark-II |
|---|---|---|
| Fins | Separate parts, glued to the tube | Printed as part of the bodyNo glued joints |
| Dry mass | Baseline | About 40 g lighter−40 g |
| Length | Baseline | About 50 mm shorter−50 mm |
| Motor retention | None — motor could back out during ejection | Copper tab set into the baseFailure mode closed |
| Flight electronics | RP2040 avionics stack | Same stack, carried overUnchanged on purpose |
| Ground electronics | Mark-I receiver | Same receiver, new printed grey enclosure |
| Sourcing | Scratch-built | Scratch-built — everything except the motor |