Due to the extremely high failure rate of shutoff's that rely on the loss of centripetal force to shut down the motor, they will no longer be allowed at the Grabber. The only shutoff's that will be allowed will be ones that are activated by the loss of line tension, and that is how they will be ground tested, no exceptions.
Examples are the piano wire type shutoff's used by Mel Lyne and Roy Glen, Sliding Bellcranks like Bobby Mears, Allen Deveuve's, and the H&R, others include Bill Maywald's, The Bellcrank Bullet, and Pete Athen's spring thing.
After 14 years of development and testing the evidence is overwhelming. The centripetal devices have proven to be extremely unreliable in a flyaway, and the line tension shutoff's have proven to be very reliable. At this point it would be negligent and reckless to allow the use of centripetal devices any longer.
Sincerely,
Jeffrey ReinBladder Grabber Contest Director.
For 10 years now, Norm and I have been co-record holders with fifteen each for the most stitches earned at the Bladder Grabber. That record was proudly crushed by Wayne McDaniel on Saturday with 20! Then I later saw a plane screaming through the pits and crash under a car right next to someone mounting a motor, I thought a chance for a new record just missed. Another flyaway flew about a quarter mile away and landed in the grass runway at the airport. A short time later I watched a real airplane land there. Another flyaway ran for about a minute and a half before dive bombing and landing six feet from a very busy intersection on highway 9. Another flew quite a distance before landing harmlessly in the field to the east. Moments later six parachutes with real people attached to them came floating to the ground. Another went into an uncontrolled helicopter spin. Quite fastenating to watch, but not nearly as much as the two hot air balloons that launched just to the north of us, with a light breeze taking them directly over the contest circle. Someone asked how many points for bell cranking a balloon? Preston's answer was "probably ten years". Four counts served conseculativly.
Every shutoff was tested prior to each match. One was severely damaged in a midair, but the other four were in perfect working order. ALL four of the shutoffs that were in perfect working order that FAILED were centripetal type shutoffs. We have been paying very close attention to the success and failures of all types of shutoffs over the last ten years or so. The conclusion is that at least 90% of the line tension shutoff's work in a flyaway. About 75% of the centrifugal shutoff's FAIL in a flyaway. What is the reason to use a shutoff if you know that it has a 75% failure rate? Just to pass rule inspection? There are about six types of shutoff's now that rely on line tension for their functionality. They cost anywhere from 10 cents to $25. Mel Lyne, Mike Rule, and Pete Athens all use a 10 cent version. A piece of piano wire that bolts to the motor mount, or in Pete's case, a simple spring with fuel tube running through it.
With the high failure rate of the centripetal type shutoff, we have decided that we can no longer allow the centripetal, (or centrifugal if you are over 50 years old) to be used at the Bladder Grabber. All shutoff's must rely on the loss of line tension when they are tested on the ground, no exceptions. If anyone needs assistance in finding the information on the six available shutoff's that will be allowed at the Grabber, feel free to contact me.
This page was upated May 3, 2007