2005 Masters maneuver #4 - Warning

[Rcmaster199 at aol.com]

Maybe I am thick and don't get it. WHAT IS IT with this  maneuver??
 
This is about as easy as the top snapping one to do right. My  Temptress tube 
is aluminum and Im not bending tubes. What gives?? I did 15 or 16  of these 
back to back to back to see what the hubbub's about and didn't see an  issue. 
 
Are you talking 100's here or what?
 
MattK

 
In a message dated 1/7/2005 7:41:21 PM Eastern Standard Time,  
pattern4u at comcast.net writes:

This is a sort of public service  announcement, or at least please regard it 
as a "Heads-up".
 
For all of you who are flying or will be flying  the Reverse Avalanche you 
might want to check your wing tubes and phenolic  tube wing supports.
 
It seems that if you go into the snap a bit hard  you can bend your wing tube 
or, in the worst case scenario break, your wing.  The plane is pulling some 
G's at the bottom of the loop and then you  add more by putting in a lot of 
elevator to get a good break for the  snap.
 
Last year I had several incidents reported to me  and my initial reaction was 
to say that they were probably not flying the  maneuver correctly. "You need 
to slow the plane down at the bottom of the  loop", I said. I must add that 
what I said did not impress an  FAI and pilot and District masters champion very 
much. :-(
 
So strapping on my asbestos underwear I decided  to do some testing of my 
own. At the end  of November 2004 it was nice here in NJ. I took the Focus-2 and 
the  Temptation out for a day of Masters 2005. Both planes were inspected for 
tube  tightness and the wing covering touched up with the glove-iron.
 
Twelve flights later and an average of 10 reverse  avalanches in each flight 
I went home thinking all was well. (It got cold and  a bit dark too).
 
Back in the shop the first thing that I  noticed was new wrinkles in the 
covering on the Temptation wings. Nothing  was loose. To test this I put the 
wing-tube in the wing and leaned on it a  little. All was well but I was beginning 
to think that the wing must  have flexed to cause the covering to loosen up. A 
bit like what the  covering sometimes does around the aileron horns. It this 
case it was at the  roots above the tubes - both sides.
 
Then I turned to the Focus-2 wings. Not good! The  wing-tube could now be 
moved up and down and I could hear foamy crunches in  both of the wings. Both 
wings have Carbon tube  wing tubes and it dawned on me that they could not bend 
(much) or stay bent.  That is why I had not seen this before. The forces were 
applying  themselves to the ends of the wing tubes. I opened up both panels and 
added  epoxy and micro balloons to stabilize the sub ribs. It was an easy 
repair but  could have been a lot worse if I was not looking for it.
 
I am advised that stress damage is  cumulative and that it does not show up 
initially. It certainly had  not revealed itself while I had been demonstrating 
the 2005 schedule over  the late summer of 2004. So where does this leave me? 
 I think we have a  potential problem that requires frequent preventative 
equipment inspection  depending upon the planes that you fly. If you can slow 
down your plane and it  is at around 10 lb you may never see this happening.
 
I would strongly advise checking your  wing with the wing tube in place to 
look for tube movement. Also look for  straightness if you have an ali-wing-tube.
 
This situation is a bit unique for me. It is the  first time I have been 
involved with a maneuver that you don't know you  are doing it wrong unless you 
fly it that way too many times. And then only if  the wing shows damage or even 
worse it breaks in the air.
 
Regards,

Eric Henderson.
 
P.S. The only time I remember seeing a reverse avalanche before is  in the 
hardly flown? current FAI Finals  schedule.



 
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