This is the second aerosan helicopter, based on the NKL-6.
I decided to make it a coaxial, similar to the
Yakovlev EG:
![](https://sites.google.com/site/stingraysphotoarchive2/_/rsrc/1339207381464/home/%D0%AD%D0%93-21_edit.tif)
I was dreading either scratchbuilding in plastic or designing the rotor assembly in 3D - but in the end it was relatively easy.
Using that picture of the Yak EG and a side-view line drawing, I made a coaxial rotor assembly that's similar. I printed the parts out today:
![](https://i.imgur.com/mETupiQ.jpg)
Some of the support arms for the main rotor mast stuck to the supports used to print the assembly, so I replaced them with styrene rod. The balance disks on the rotor arms also suffered some distortion from lack of support during printing, but since they all came out with the same error... I decided to call it a "design feature" and not a bug. Here it is assembled:
![](https://i.imgur.com/Gir0HhS.jpg)
The top rotor turns as well:
![](https://i.imgur.com/IRYRzvA.jpg)
Overall, it came out OK. There are some issues, but not enough to beg a reprint. The blades themselves will be made of either styrene or paper. 3D printing them in resin or in ABS on the FDM printer is probably more trouble than it's worth.
I'm pretty far along with the interior and the large radial engine - a Shvetsov M-11 - which is the same engine used on the Yak-EG. The pilot's seat is just putty. I figured the pilot would need something more comfortable than wooden slats to sit on. I also added a plastic rod as a fuel line:
![](https://i.imgur.com/LPiiTYz.jpg)
Here's the engine close up. I may add ignition wires but the kit engine is pretty nice OOB:
![](https://i.imgur.com/MxclPWm.jpg)
I mocked up the engine and rotor placement. I still need to come up with an engine mount and a transmission for the rotors:
![](https://i.imgur.com/YzUTBNk.jpg)
The windows in this kit aren't as bad as in the KM-4:
Still, I cut them out and glued them in place.