Radio Controlled Starship Program

Description

I am making a fully functioning, radio controlled Starship that can take off vertically, skydive down, and land vertically. I'm using conventional RC servos, motors, and other equipment to make it happen on a small-scale model. To my knowledge, nobody else has done this before. It is a difficult engineering challenge, but that's what makes it fun.

Details

I started my Starship program the same way SpaceX did--with a Starhopper test platform. I learned many useful things from this exercise before I invested in real hardware for the Starship build:

With control via thrust vectoring (roughly) figured out, the next step was to translate what was learned on the Starshopper to a Starship. The Starship hovers with two slightly more powerful brushless motors, with the addition of fore and aft lifting surfaces that enable control in the descending skydive or belly flop mode:

A little more tuning on the starship is needed before we consider building a superheavy booster to launch it with...

For flight control and stabilization on this project, I'm using my open-source flight controller that is Arduino-based and runs on the Teensy 4.0 with MPU6050 IMU: Project Page

This project is released under the CERN open hardware license (strongly reciprocal): Home | CERN Open Hardware Licence

By using this project or files contained within, you agree to adhere to the terms within the CERN-OHL-S license.

Files

Canard FOAMBOARD X2.STL

Standard Tesselated Geometry - 1.64 kB - 12/12/2020 at 21:10

Download

Rear Surface FOAMBOARD X2.STL

Standard Tesselated Geometry - 684.00 bytes - 12/12/2020 at 21:10

Download

Nosecone X1.STL

Standard Tesselated Geometry - 692.86 kB - 12/12/2020 at 20:54

Download

Motor Mount X2.STL

Standard Tesselated Geometry - 167.95 kB - 12/12/2020 at 20:54

Download

Servo Bulkhead X1.STL

Standard Tesselated Geometry - 249.59 kB - 12/12/2020 at 20:50

Download

Components

2 × 2450kv Brushless Miniquad Motor

2 × 35a Brushless ESC

1 × 5043x3 Counter Rotating Propeller Set

1 × 1500mah 4s Lipo Battery

1 × 15a Turnigy BEC Flight controller and servo power

Project Logs

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More Flight Testing
Nick Rehm • 01/18/2021 at 15:32 • 0 comments

Recently got back out to the field with my repaired Starship from the last video. I wanted to get a better 'feel' for the aircraft while in freefall so I could make more informed design changes for the next iteration. Unfortunately, the last flight ended in another crash (my fault), this time much more spectacular.
Starship Video
Nick Rehm • 12/08/2020 at 20:25 • 0 comments

Found some free time today to get the video put together, so here it is now instead of tomorrow:
New Aero Surfaces and Paint
Nick Rehm • 12/08/2020 at 17:22 • 0 comments

After some flying, I decided it was time to change out the Mk1-ish aero surfaces to something closer to SN8 and finally give it some paint. Flight video tomorrow!
Foam Body Panels & Landing Pad
Nick Rehm • 12/02/2020 at 01:04 • 0 comments

Hover testing is coming along nicely; in my free time I turned the back of my cutting board into a landing pad for the big flight (with skydive maneuver).

I had to add foam around the body to give the 3mm carbon body spars some more torsional stiffness (tail was wagging due to differential throttle for yaw control). Video soon!
Starship Build Complete
Nick Rehm • 11/24/2020 at 15:34 • 0 comments

Just finished up the hardware build on the Starship prototype. I had the CAD model pulled up to help cross-reference as the parts came together. Most everything went together nicely, I just need to make some minor changes to some of the printed parts for better tolerances/additional features. I still haven't figured out a plan for landing gear--it will most likely be passive, but for now I think I'll just grab it out of the air. Stay tuned for a build video and parts files!

Now on to hover testing, then the maneuver never attempted before: the skydive.

Avionics bulkhead:
3D Printed Parts
Nick Rehm • 11/15/2020 at 01:02 • 0 comments

All the parts are off the printer and cleaned up. Just waiting on some carbon rods to arrive in the mail to complete the structure's assembly.
Starship Design Underway
Nick Rehm • 11/09/2020 at 15:48 • 0 comments

CAD design is finished--printing test parts now to verify tolerances, and parts are on order for the complete build.

View all 7 project logs

Build Instructions

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Building the Starhopper

Cutting out and gluing together the internal structure from foamboard:

Motors attached to 3D printed motor mount and hot glued to the structure. ESCs attached with double sided tape:

Connecting the servo linkage for the control surfaces:

Installing receiver and Teensy 4.0-based flight controller:

Internals wrapped in cylindrical foam and landing legs glued on:

Building the StarShip

Parts all designed in Solidworks 2020 and masses used to estimate vehicle center of gravity:

Print all the parts in PLA or ABS (quantities of each part listed in part name):

Install motor mounts to motor bulkhead with m3 hardware:

Install 4 SG-90 servos to servo bulkhead with hot glue and servo hardware:

Install electronics on electronics bulkhead with double sided tape:

Install servos in the nosecose and assemble canard hinge:

Slide all subassemblies over carbon spars of ~400mm length. Servo bulkhead placement is dictated by rear flap hinge. Pin all parts in place with hot glue. Cut out aerodynamic surfaces from foamboard and slide into hinge pieces:

Cut out foamboard to snugly wrap around outside and pin in place with tape so that it can be taken off later to access electronics:

Give it some paint:

Discussions

Kushal Neupane wrote 01/16/2023 at 16:41

Is there any alternative microcontroller for teensy 4.0?

Are you sure? yes | no

joshbruce wrote 03/09/2021 at 09:03

Just wondering, is there anyway you could create a servo-rod bending guide? Great project by the way!

Are you sure? yes | no

Andrew Green wrote 12/17/2020 at 04:28

It's an amazing project. I bet it takes a lot of time and effort but it worth it. Good luck! I will follow you for updates.

Are you sure? yes | no

thatrandomcatboi wrote 12/16/2020 at 13:31

Hello! I recently watched your starship video through Reddit and was astounded and am incredibly interested in building one myself, but i have no experience in coding and was wondering if you could share the code used? particularly for the free fall control surface part, as i am planning on using a different method for ascent from propellors, if you could share that would be greatly appreciated, thanks!

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Nick Rehm wrote 12/16/2020 at 22:25

Stock code is available here: https://github.com/nickrehm/dRehmFlight

Here is the only modification to the default code made within the control mixer function:

m1_command_scaled = thro_des - yaw_PID;
m2_command_scaled = thro_des + yaw_PID;
m3_command_scaled = 0;
m4_command_scaled = 0;
m5_command_scaled = 0;
m6_command_scaled = 0;

//trim values for takeoff
float LC_trim = 0.11;
float RC_trim = 0.89;
float LF_trim = 0.1;
float RF_trim = 0.93;

//trim values for skydive
float LC_trim_dive = 0.46;
float RC_trim_dive = 0.54;
float LF_trim_dive = 0.55;
float RF_trim_dive = 0.5;

//trim values for landing
float LF_trim_land = 1.0;
float RF_trim_land = 0.0;

float RTV_trim = 0.52;
float PTV_trim = 0.55;

float K_yaw = 0.4; //aero surface stabilization gain on yaw (roll in skydive)
float K_pitch = 1.5; //aero surface stabilization gain on pitch
float K_roll = 1.0;

if (channel_6_pwm > 1800) { //takeoff with no control surface controls
s1_command_scaled = LC_trim; //left canard
s2_command_scaled = RC_trim; //right canard
s3_command_scaled = LF_trim; //left flap
s4_command_scaled = RF_trim; //right flap
s5_command_scaled = RTV_trim - roll_PID; //roll thrust vectoring
s6_command_scaled = PTV_trim - pitch_PID; //pitch thrust vectoring
s7_command_scaled = 0;
}

if (channel_6_pwm < 1800 && channel_6_pwm > 1300) { //sky dive with full control surface controls
s1_command_scaled = LC_trim_dive + K_pitch*pitch_PID - K_yaw*yaw_PID + K_roll*roll_PID; //left canard
s2_command_scaled = RC_trim_dive - K_pitch*pitch_PID - K_yaw*yaw_PID + K_roll*roll_PID; //right canard
s3_command_scaled = LF_trim_dive - K_pitch*pitch_PID - K_yaw*yaw_PID; //left flap
s4_command_scaled = RF_trim_dive + K_pitch*pitch_PID - K_yaw*yaw_PID; //right flap
s5_command_scaled = RTV_trim - roll_PID; //roll thrust vectoring
s6_command_scaled = PTV_trim - pitch_PID; //pitch thrust vectoring
s7_command_scaled = 0;
}

if (channel_6_pwm < 1300) { //rear flaps retracted and stationary for hover slam
s1_command_scaled = LC_trim; //left canard
s2_command_scaled = RC_trim; //right canard
s3_command_scaled = LF_trim_land; //left flap
s4_command_scaled = RF_trim_land; //right flap
s5_command_scaled = RTV_trim - roll_PID; //roll thrust vectoring
s6_command_scaled = PTV_trim - pitch_PID; //pitch thrust vectoring
s7_command_scaled = 0;
}

Are you sure? yes | no

Radio Controlled Starship Program

Description

Details