This wind load information was produced by Bill Snapp. Bill is an engineer and the builder and owner of a beautiful RV8A. We thank him for the time and effort that he has so kindly volunteered. Bill has helped us better understand the anatomy of high energy wind events and why the Gust Buster system works so well.
Gust Buster Engineering Information
Want to sleep better at night when your airplane is on the ramp in the wind? Use a Gust Buster Gust Control System and you will, here’s why.
RV rudder damage as reported by RV owners indicates that damage will occur during wind gusts of 50 kts. or more, (the exact wind velocity that damage occurs is not known, 50 kts or a bit less). In most of the cases we know of the wind was in the neighborhood of 90 degrees to the rudder and the rudder was locked when the damage occurred. In some cases the locking device failed in other cases the locking device did not fail but in either case the rudder was damaged. No doubt the bulk of the damage happens during the sudden and significant load increases of the gust.
How the Gust Buster Mitigates the Threat
During high energy wind events the Gust Buster allows the rudder to move against spring pressure to or near the airplanes mechanical rudder stop (appx. 35 degrees). Engineering information reveals that if the wind is 90 degrees to the rudder during the wind event, (worst case scenario) and the rudder is allowed to move to 35 degrees of deflection, the wind load on the rudder will be reduced by at least 19%. A wind gust of 50 kts. produces 71 lbs. of force on the RV7, 9 and 10 rudders. With the rudder deflected 35 degrees the wind load is reduced to 58 lbs of force. *
The Advantage of the Springs
1) In most cases the compressed spring becomes the rudder stop sparing the airplanes mechanical stop from any abuse, (this is the case when the rudder control is used on the rudder pedals that the cables are connected to). 2) The springs also act as shock and energy absorbers during gusts when the rudder is most vulnerable to damage. 3) Depending on the type of airplane the spring will absorb approximately 40 lbs. to 49 lbs of the force on the rudder while it is compressing during rudder travel.
Bottom line, your chances of flying your airplane home on schedule after a high energy wind event with a well rested pilot at the controls goes way up if you use a Gust Buster.
*Engineering information supplied by Gust Buster customer, RV 8 builder, owner and engineer Bill Snapp. We are grateful for his professional help and friendship.