My daughter, her friends and myself have having a blast with @271828's Pull String Helicopter. But I had to see if I could take it up a notch. I have a bunch of 2204/2205 brushless motors and ESC's laying around so figured a powered version would be fun.

Since 271828 was kind enough to share his solidpart files I was able to open the hub in Onshape and remove most of it, then add a 5mm hole in the center and an opening sized to fit the nut on this particular motor (it's NOT sized to fit a standard 5mm nut as the only ones I had on hand had large flanges on them which made them too large to fit inside while maintaining the integrity of the hub.)

The Onshape project is here if anyone wants to modify this further:
https://cad.onshape.com/documents/120c05cbd1daa0960651817d/w/0259438f83c0697b2e8aff1b/e/799261b008764e4709b70116

I'm also working on a modification of the handle to mount the 220x motor on top and hold the electronics.

Right now I'm just using this with a 12a "simon series" emax esc because it the first small ESC I grabbed out of my parts stash. But I suspect an ESC with better active braking would work much better since it should allow for a quicker release of the helicopter. I'm just using a servo tester to control the motor, but when I get a bit of time want to switch to an arduino so you can just push a button and it will spin up then stop automatically. I tried it on both 2s and 3s lipos and 3s did seem to get a bit more altitude but not a lot.

Kind of thinking about making the handle able to hold to 18650 cells for power...but worried they can't put out enough current for this. Need to run some tests first.

Still working on modifying the handle - 18650's won't cut it...this thing is drawing 22amps on a 3s lipo. And this is just using a servo tester. Once I wire in a micro to make it pushbutton should get better launches since it can stop the motor quicker without the time it takes me to turn the knob:

https://www.youtube.com/watch?v=7OTZb2jl0rY