nvrtd.design Blog

To start on the second prototype of the V-22 Osprey, I took the pair of KDS 450 helicopters and stripped them of everything but the main shaft housings and landing skids. Each rotor disc is 28" (711.2mm) in diameter. If I compare that to the full-scale rotor disk of the V-22 of 11.61m, I get a scale factor of 16.87:1. In Fusion360, I scaled a 3-view drawing of the V-22 to the full size of the model and measured the distance between the rotor shafts and came up with a scale value of 33.2". I modeled a connecting block in Fusion360 that utilizes the original bolts and pattern of the KDS helicopter to attach to each side. The connecting boom is a piece of 1/2" x 5/8" C-channel aluminum that is 1/16" wall thickness. I moved the control electronics over from the first prototype but redid the Arduino mixing code. I found some other PWM reading code that implements Pin Change Interrupts instead of the dedicated external interrupt pins which are very limited on most Ar...

I'm calling an end to the first prototype build for this project.  A few things changed between the first attempted flights.  I gave the thing a serious diet by: replacing the wooden boom with carbon fiber and redesigned/reprinted the motor mounts replaced the separate ESCs with a 4-in-1 drone ESC module replaced the Frsky X4R with a FrSky XSR replaced the 2S 2000mAh battery with 2x 1S 600mAh batteries in series replaced the Arduino Mega with an Arduino Micro generally lightened everything up where I could The new all-up weight is 217g, but it's still too heavy and the tolerances in these micro helis aren't good enough.  I tried a few hanging control tests, and there's so much slop in the control linkages that it ping-ponged all over and never stabilized. For Phase 2, I have a pair of KDS 450 helicopters that I'd like to use for the next prototype.  They run on 3S 2200mAh batteries and are certainly more capable of lifting a larger airframe.  Th...