I've been to Grattan once. Very nice track, getting a little rough in a few spots but overall one of my favorites. That picture is probably from a spot on the downhill back straight. It's at a wide open down hill section. And just before you have to break for a right hand 90 degree turn there's that jump like section. The faster guys can really fly over that hill and then land and break hard for the 90. The slower, scared guys break before the jump. But you really have to be moving fast to get that kind of air like the picture.
The one time I was there I saw Jay Springsteen racing one of the Harley roadracers. He comes down this long hill in first place in his race on the first lap, hits this jump section and his right hand comes off the handlebar as he lands. So he's got no brakes for the right hand 90 and goes straight off the track. He manages to keep it up but by the time he gets back on the track he's in last place - after the second wave comes by him. At that point he starts riding at an incredible pace. Passes everyone in both waves and takes first place overall. In an eight lap race. Harley should have given him a real roadracer back in the day. Or at least allowed him to ride another company's bike for roadracing. He could have been one of the best.