RC Starhopper

[NickRehm]

In anticipation of SpaceX's sn8 15km starship hop, I've decided to start my own space program

First up, we need to start small, so I'll be building the famous 'starhopper' vehicle:

After this, I would like to move to a full 'starship' that can fly up vertically, parachute down, then land vertically again. In the spirit of VTOLs and RC, I'll be using brushless motors and props instead of rocket motors

The internal structure is just a '+' type construction from dollar tree foam that will allow for two counter rotating motors, and two control surfaces for roll and pitch control:

The motors are supo 1000kv with 8x4 props, might move up in prop size later to 9x5:

I'm using two 12a blheli ESCs and the Teensy 4.0 with MPU6050 as my flight controller using my dRehmFlight code: https://www.rcgroups.com/forums/show...-Stabilization

I wrapped the outside with more foam for that beautiful water tower look, and added landing legs reinforced with 1/4" dowels.

Height is about 20" and diameter of main frame is about 12". I wanted to go a little bigger than my power system so there is some flexibility with prop size. Also wanted plenty of room to mount the electronics, as close to the top (between the two motors) as possible, so that the control surfaces will have a larger moment arm for control. I've done some test flights in my living room to test control gains and have it flying pretty well. One thing I'm learning with these types of vehicles is that they need crazy high gains with quite a bit of damping term. Waiting on some 9x5 props in the mail to test out for more thrust, as I'm approaching the upper limit of max TOW before I paint her up.

Stay tuned for flight footage and more details on the build

 

[the rc project]

This is sick!

 

[LitterBug]

You could easily mod this a bit and have a flying Frosty the Snowman too.... ;-)

 

[L Edge]

If you do clockwise, counterclockwise motor directions you will resolve some of your problems on liftoff. Built a Sidewinder missle that was able to lift off and land with no problem.

 

[NickRehm]

If you do clockwise, counterclockwise motor directions you will resolve some of your problems on liftoff. Built a Sidewinder missle that was able to lift off and land with no problem.

yup, currently set up for counter-rotating. I get ok yaw control authority with stabilized differential throttle

You could easily mod this a bit and have a flying Frosty the Snowman too.... ;-)

Was planning on a VTOL Santa's sleigh, but might have to repurpose this too haha

 

[L Edge]

yup, currently set up for counter-rotating. I get ok yaw control authority with stabilized differential throttle


Was planning on a VTOL Santa's sleigh, but might have to repurpose this too haha

Are you going to explain what you are controlling(yaw, pitch, roll) for the FC viewpoint? Would be interesting. For the yaw control(vert?), are you saying that your going to vary the 2 motors?

 

[NickRehm]

Here is the control mixer I'm using within my code (base code available here: https://github.com/nickrehm/dRehmFlight):

Both motors get raw throttle command from me, and differential rpm for yaw control (from PID controller). Then each control surface gets roll and pitch stabilization from the PID controller such that my stick input corresponds to stabilizing on an angle setpoint. I'll have a video by the end of this week explaining things a little better + some flight footage

 

[NickRehm]

Finally some flight footage... + a little extra

 

[NickRehm]

Starting the starship build this weekend... not sure if I should start a different thread since this will be a totally different vehicle...?

 

[NickRehm]

Some progress on the Starship

 

[the rc project]

Oh this just got really cool really quick!

 

[NickRehm]

Hover testing 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)

Had to add foam around the body to give the 3mm carbon some more torsional stiffness (tail was wagging due to differential throttle for yaw control). Video soon

 

[NickRehm]

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! https://www.youtube.com/channel/UCPe7XrmOPtz4OjL6KGtvJMA

 

[NickRehm]

Found some free time today to get the video put together, so here it is now instead of tomorrow:

Fingers crossed for successful full scale flight test this evening!

 

[Ryan O.]

Found some free time today to get the video put together, so here it is now instead of tomorrow:

Fingers crossed for successful full scale flight test this evening!

Nice job with the Starhopper and the SN8 less than half an hour till the full scale launches if everything goes according to plan!

 

[NickRehm]

Nice job with the Starhopper and the SN8 less than half an hour till the full scale launches if everything goes according to plan!

scrub :/

but another reason to be excited for tomorrow

 

[Ryan O.]

scrub :/

but another reason to be excited for tomorrow

Yeah, I I'll have NSF's, Everyday Astronaut's, WAI's, and SpaceX's streams up on different tabs tomorrow so i don't miss it incase one goes down We also got some cool audio and video from Hopper's cameras and the ones on SN8, which is cool in itself. Although hopefully that piece of something falling from the raptor closest to the camera wasn't a part of the Raptor, although that would explain the scrub

 

[PsyBorg]

Nice start mate. That already looks pretty stable. That first video sequence looked near perfect except for what I think is pitch gains. You can see it with the look down footage where the motor is oscillating quite a bit.

It laid over nicely and was more stable then other attempts I seen other people start with, I think you are on the right track with the fins forming a dihedral.

Maybe paint the under side a different color for orientation as it is horizontal. That way it would be easier to make adjustments as there is no guess work needed from unstable or nervous launches where you might lose track of what axis needs adjusting.

Final thought.. when I used to launch rockets we always had to lean the guide rail over at a pretty significant angle into the wind to make the rocket be over the launch pad at the apex of the ascent. Maybe pre load the pitch or roll at launch to do that as a flight mode thing then once its in full motion flip to a normal flight mode then the third mode at the apex to lay it over for decent.

 

[NickRehm]

Maybe paint the under side a different color for orientation as it is horizontal. That way it would be easier to make adjustments as there is no guess work needed from unstable or nervous launches where you might lose track of what axis needs adjusting.

Final thought.. when I used to launch rockets we always had to lean the guide rail over at a pretty significant angle into the wind to make the rocket be over the launch pad at the apex of the ascent. Maybe pre load the pitch or roll at launch to do that as a flight mode thing then once its in full motion flip to a normal flight mode then the third mode at the apex to lay it over for decent.

Great idea with the paint... might do the underside black so it's easier to see.

Yea, will need to be more mindful of wind next time I go out to fly. I will try to launch into the wind and then do the transition into the wind as well, hopefully will land me close to where I started

I also want to strap an fpv cam to it and try much higher altitude so there's more time to test the control surfaces in an extended freefall

 

[CrazyFastFlying]

Hey, this project it really cool! I'll be watching this thread!