The Street Glider, a new kind of Hovercraft from billyd

Here is a short demo of the street glider
https://vimeo.com/659992058

Note: You will need a printer with at least a print area of 290mm x 280mm in X and Y. This is the bare minimum size. Perhaps I will design some split models in the future, but it will be difficult to do and make it come out as well as the one piece version.

Update 12-19-21 Added build instructions and an exploded view of the build
Update 12-21-21 I have removed the work in progress designation but upgrades will continue to appear as I gain experience with this model.
Update 12-22-21 Updated build instructions. Please re-download small errors have been corrected.
Update 12-23-21 More corrections to build instructions and hardware list
Update 12-26-21 Still more tweaks to the build instructions
Update 12-27-21 Yep I changed the build instructions again just a couple of typos and omissions.
Update 12-29-21 This time I really think the build instructions are finished. geez lol.
Update 1-2-22 Added two piece skirt. This design must be glued together with loctite 406. By making it in two pieces, the bottom half can be printed flat to the bed, allowing for much better bending strength. Updated build instructions to include two piece skirt assembly. Added loctite 406 to the hardware list.
Update 1-8-22 Revised Diff All with better PIDs for the default 6s setup. You may need different PID settings depending on your setup.

I printed a hovercraft from thingiverse recently by jscaylor (thing:2700850 thanks for the great design and inspiration to do this project!) and I really liked it, but it was lacking in a few areas from a performance standpoint. And also, the garbage bag used for the raft constantly required replacing and was difficult to install.

So I decided to develop my own hovercraft. I designed this from the ground up and I believe it is completely original. The rudder system is similar to other 3d printed designs, but I made some changes to how they are installed, and created them from my own original profile design. So at best they were inspired by previous designs, but different enough for me to call them original work. All other facets of the design were created solely by me (with the exception of the XT60 panel mount see below). I am unaware of any other model rc vehicle quite like it. This design uses a skirt with fingers printed in one piece in TPU instead of an inflatable bag. It will last longer, and screws in place for easy replacement.

One of the problems with hovercraft is when you have minimal drive thrust you have very little steering authority if any. Also alot of unwanted yaw is created by the various props required to drive a hover craft. While some have used counter rotating props to combat this, I have taken it a step further, a flight controller and INAV firmware!

The Street Glider uses a stack consisting of a flight controller, and a 4 in 1 esc (with a pdb). It uses four brushless 2005 size 2800kv motors, two for required pressure for hovering, and two for the drive thrust, all using triblade 3" props. Installed in the flight controller is open sourced INAV firmware using the rover mix with customization (I will share my configuration). The flight controller uses it's brains to help drive in a straight line when the pilot desires it (does it hands off), as well as provides for tremendous turning response in yaw, regardless of drive thrust or speed. It accomplishes this by using all four motors in a turn (along with the traditional rudders), with the hover thrust motors using different speeds to create a torque bias, and the drive motors using speed differential thrust to increase the turning rate regardless of forward velocity. You can spin this hovercraft standing still in a circle, and stop on a dime by quickly spinning 180 and using drive thrust to stop. Yes you stop like this in any hovercraft, but with this design you do it nearly instantaneously and you don't need drive thrust to initiate the turn. The amount of control is incredible.

The only downside of this design is it needs to stay on firm smooth terrain or paved surfaces (for now, because I hope to continue to improve the skirt design in the future to handle larger obstacles). It will handle small bumps and elevation changes, But anything taller than 1/2 of an inch will probably stop it. So it's not really a true hovercraft. Think of this more of a street glider racer. In fact that's what I call it. And it's very fast. My electrical setup (details in the files section) can handle from 4 to 6s batteries. On 6s it is absolutely a screamer and a blast to drive.

This design makes extensive use of heat set inserts and plenty of hardware throughout to join the pieces together. I made this with an eye towards premium quality. The only place where screws self tap is the rudder sync bar to the rudders.

Finally I am by no means an expert in INAV so my configuration is just the tip of the iceberg as to what can be done by those with more experience. And I am anxious to see what users come up with as improvements to the firmware setup in the future. It is my hope we can continue to improve this design over time.

ps Thanks to fuzebox for the xt60 panel mount design (thing:5019436) which I use in this project.