R-38 Pneumatic Bourke Engine

myminifactory

The R-38 is the third rotary engine developed after the R-66 and R-52. It measures 38 x 38 x 48 mm³, making it the smallest in this series so far. The R-38 also boasts the fastest design and better airflow through 4 mm pneumatic tubes than its larger counterparts. Detailed instructions can be found on Thingiverse. The crankshaft is entirely metal, with a 3 mm crank radius that results in a piston stroke of 6 mm. With a piston surface area of 16 x 12 mm², which equals 1.92 cm², the R-38 yields a piston force of 38 N at 0.2 MPa (2 bar) pressure. Together with this, the theoretical torque is 110 Nmm at 0.2 MPa. Filament sponsorship is provided by Fillamentum, using all PLA in three colors: Everybody's Magenta for the rotor, Pearl Night Blue for the housing, and Gold Happens for the bearing cage.