On September 1st, 1973, I came within an eyelash of getting killed in my RS-15 sailplane.
It started with a normal takeoff on the third day of Region 6 contest at Ionia, Michigan. The first indication of trouble came when I was unable to stay above the towplane's skip-stream. My first impulse was to release, but when my ship slowly climbed into position I attributed the poor response to the left crosswind coming over the hill at the side of the runway. As the towplane established its climb the RS-15 just wouldn't follow. A quick glance at the base of the stick confirmed that it was all the way back and not jammed by the parachute. At this point I pulled the release.
With the stick all the way back, the ship continued down in a shallow dive until it hit the ground. The hydraulic shock struts cushioned the impact very well, but when the tail went down, the ship zoomed back up to fifty or sixty feet in spite of full forward elevator control. At this point, the nose was swinging to the left so I applied full right rudder. The ship went into a violent dive which continued to steepen in spite of all corrective efforts.
I struck the ground at about 80 mph with the nose down nearly 30 degrees convinced that neither the ship nor I would survive the impact. The crash was deafening. It stopped the launching and gained the attention of everybody on the airport.
When the dust cleared away I looked around and was surprised to find that the wings, tail suraces, boom and pod were relatively intact. Unbelievably, I was uninjured! (Two days later my neck and chest were pretty sore from the tremendous deceleration and consequent restraining forces of the shoulder harness.)
Inspection of the control system revealed that the left ruddervator was disconnected. Like all HP designs, the ruddervators can't disengage from their actuators unless they are rotated beyond the vertical folding position.
Lots of volunteer help at Ionia assisted in the assembly. This is probably when it was disengaged. We made a control check just before takeoff and all surfaces moved. This proves that moving the controls is not a safe check on V-tailed RS and HP sailplanes (and probably is not anymore reliable on other types of sailplanes) because a disconnected control rod can push its bellcrank and make its surface move. I have always relied on my crew to visually inspect the ruddervator drivers when tail surfaces are unfolded and pinned. As a result of this accident it was discovered that even though they understood the actuating mechanism, they didn't check for proper engagement because I hadn't told them to.
This experience indicates that every pilot should personally check all assembly controls and attachment fittings before each flight whether he flies a HP, RS or any other sailplane. He may find that he has not properly trained his crew or that someone else less skilled has helped and left a dangerous situation for him to discover the hard way.
A thorough personal preflight check may save a life -- you own.