Originally Posted by EK4457
I was about to start up my Tommohawk at the fuel pump when there was a large 'thump' behind us. Both me and my instructor turned to see that the Grob had ballooned up after initial contact with a dry and dusty 27L and was coming back down with an accute nose down attitude. The a/c then hit the grass to the left of the runway, nose first, and ballooned again. This happened another two or three times, each time getting closer to the tower
EK
I believe the technical description is 'porpoising'.