Junkers Ju 87 withstand dives of . The Jumo 211D in-line engine was installed, replacing the R-1s Jumo 211A. Due to an increase in overall weight by , the Ju 87 R-2 was slower than the Ju 87 B-1 and had a lower service ceiling. The Ju 87 R-2 had an increased range advantage of . The R-3 and R-4 were the last R variants developed. Only a few were built. The R-3 was an experimental tug for gliders and had an expanded radio system so the crew could communicate with the glider crew by way of the tow rope. The R-4 differed
Grinnell Aeroplane Grinnell Aeroplane The Grinnell Aeroplane Company was an American aircraft manufacturer based in Grinnell, Iowa, that built aircraft prior to World War I. The company was formed to develop the "Scout" aircraft designed by Billy Robinson. Robinson trained at the Max Lille school in Cicero, Chicago as a mechanic, learning to fly Wright aircraft and Nieuports. He worked for a brief time as a partner in the National Aeroplane Company before leaving to Iowa in 1913. His custom built parasol was the first to fly airmail from Iowa, setting a non-stop distance record of 390 miles. In 1914, the Grinnell