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  #1  
Old 05-11-2014, 09:15 AM
Norman CYYJ Norman CYYJ is offline
 
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Location: Victoria B.C.
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Default Performing Loops

I was up doing loops and rolls the other day with a average size guy(180 lbs).
At the top of the loop just before easing the back pressure off it felt like and sounded like someone hit the tail of the plane with a two by four. I landed and inspected the tail section, no damage or cracks. Tried again with different entry speeds and still this happened. I have never experienced this before have any of you? OAT was around 65 and alt. was 5500 asl.
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  #2  
Old 05-11-2014, 09:33 AM
andrewtac andrewtac is offline
 
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Location: Friendswood TX
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Were you doing multiple back to back loops. Maybe hitting your own prop wash? In other aircraft I've done it in level turns, but never vertical.
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  #3  
Old 05-11-2014, 09:42 AM
Norman CYYJ Norman CYYJ is offline
 
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No it happened on the first loop and I was already almost completely inverted easing the back pressure off. I have hit my own turbulence before horizontally and vertically and feeling was not the same.
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  #4  
Old 05-11-2014, 09:43 AM
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chepburn chepburn is offline
 
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You probably have thought of this already.... but did you look for an unknown object floating around in your tail area that came loose?
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  #5  
Old 05-11-2014, 09:49 AM
Norman CYYJ Norman CYYJ is offline
 
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Yes, I did look, there were no loose objects.
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  #6  
Old 05-11-2014, 09:59 AM
luddite42 luddite42 is offline
 
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Loose item in baggage compartment? I cannot think of anything except for a sizable piece of FOD that started floating around once you got into zero G territory at the top of the loop.
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  #7  
Old 05-11-2014, 10:00 AM
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Paul Tuttle Paul Tuttle is offline
 
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Check for oil canning on the bottom skin of the fuselage. I had a similar sound and that's what it turned out to be. It got my attention the first time or two.
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  #8  
Old 05-11-2014, 10:12 AM
gerrychuck gerrychuck is offline
 
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Location: Moose Jaw, SK, Canada
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When I was training in my old Cherokee 140 I would get a "bang" whenever we did a spin, and the top bulkhead panel separating the cabin from the tail cone would pop out. Happened every time, and definitely seemed to be a little oil canning in the fuse.
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  #9  
Old 05-11-2014, 10:24 AM
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Russ McCutcheon Russ McCutcheon is offline
 
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Quote:
Originally Posted by Norman CYYJ View Post
I was up doing loops and rolls the other day with a average size guy(180 lbs).
At the top of the loop just before easing the back pressure off it felt like and sounded like someone hit the tail of the plane with a two by four. I landed and inspected the tail section, no damage or cracks. Tried again with different entry speeds and still this happened. I have never experienced this before have any of you? OAT was around 65 and alt. was 5500 asl.
I outlined the key, low airspeed wile still loaded, the tail stalled, been there done that. More speed on entry and a little more G at entry will get you to the top before it slows to a stall speed. this happens a lot easier two up then solo.
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  #10  
Old 05-11-2014, 10:48 AM
luddite42 luddite42 is offline
 
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Quote:
Originally Posted by Russ McCutcheon View Post
I outlined the key, low airspeed wile still loaded, the tail stalled, been there done that. More speed on entry and a little more G at entry will get you to the top before it slows to a stall speed. this happens a lot easier two up then solo.
I'm unclear on what you are connecting, or what a "tail stall" is. You can stall, buffet, and snap airplanes every which way and not hear banging in the airframe. Oil canning is a good thought. Though this is definitely not a "typical" thing with RVs and aerobatics, no matter how you choose to fly through loops.
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