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05-19-2011, 01:14 PM
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Join Date: Jan 2009
Location: Denver, CO
Posts: 590
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Quote:
Originally Posted by Bavafa
I saw the same number which I can not even imagine what must have been like over 10K FPM decend.
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It actually states a max rate of 12,000 fpm...which comes out to about 136mph if my math is correct.
__________________
Ron Duren
Mechanical Engineer
"SportAir PhD"-RV Assembly/Composites/Electrical
Denver, CO (KBJC)
RV-7 'Tip Up'
Flying!! as of 3/16/14
IO-375/ WW 200G-CS/ SkyView/ Dual P-mags
N531R "Wablosa" Wings of Red
http://www.ronsrv7project.blogspot.com
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05-19-2011, 01:25 PM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by RV7Ron
It actually states a max rate of 12,000 fpm...which comes out to about 136mph if my math is correct.
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Plus, the forward speed.
L.Adamson
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05-19-2011, 01:46 PM
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Join Date: Aug 2005
Location: OKC, OK
Posts: 687
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Sure looks like flutter
Flutter sure seems to be the probable factor here, the way I see it. The extreme degree of damage; the high airspeeds, and the heavy rudder all indicate/contribute to a likely flutter incident. The pilots apparent inexperience in aerobatic flight may also have been a contributor. Finally, the video DID reveal a sudden onset of airframe vibration during the high speed pull out:
Quote:
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During a pull-out from a rapid descent, there was a sudden onset of an airframe vibration (shuddering around the longitudinal axis), which was followed by a yawing motion, a roll and ground impact.
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The report talks about overstress as a possible cause for the rudder failure, but I don't think that's a likely explanation, in and of itself. I think, given this pilot's limited aerobatic flight experience, he *may* have ham-fisted the rudder while attempting to follow lead, thus creating the excitation event himself. At any rate, something induced the flutter incident (if it was indeed flutter), be it pilot, wake turbulence, or another external factor.
__________________
?The important thing in aeroplanes is that they shall be speedy.?
- Baron Manfred von Richthofen
RV8 under construction
RV4 - Sold
United B777 FO, Chicago
Aero Engineer
RV8
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05-19-2011, 01:55 PM
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Join Date: Mar 2006
Location: Ft Myers, FL
Posts: 276
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In flight breakup
With all respect to the deceased party, it appears this subject dovetails quite appropriately with the missives from Van regarding safety concerns. The speeds being flown by this pilot are extremely fast for an RV-7A and certainly overstressed the empennage. The laws of physics apply to all. The biggest concern here is that, potentially, activities such as this are what could wreak the greatest havoc on the homebuilt aviation community at the hands of the feds. Exceeding Vne is pilot error not a design flaw in the airplane but some individuals in positions of authority would look at this as an opportunity to take draconian measures to limit our chosen lifestyle. What I take away from this is that it is imperative that we all use our heads and not think that since we are building experimental aircraft and are exempt from some of the stricter measures imposed on certified aircraft manufacturers that we are somehow also exempt from the laws of aerodynamics. An airplane crash gets the attention of many individuals in positions of authority who can adversely affect our ability to fly.
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Bill Near
RV-7A Flying
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05-19-2011, 02:01 PM
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Join Date: Jul 2005
Posts: 1,347
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That has to be chilling video to watch.
And yes, wake encounters in trail can be unnerving and maybe more dangerous than I thought.
__________________
Mike W
Venice, FL
RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
N164WM
N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
Last edited by fl-mike : 05-19-2011 at 02:04 PM.
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05-19-2011, 02:23 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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Before this report, I had a ton of concern about what really happened in this accident. The report settles this in my mind. There is no design flaw associated with this accident.
These planes are not indestructable and this event/report as sad as it is proves it.
Know the limits of yourself and your aircraft!
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05-19-2011, 02:41 PM
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Join Date: Sep 2007
Location: pittsburgh pa
Posts: 533
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I agree with most things said here
I do not believe that exceeding Vne with a slightly mis-balanced rudder was the total root cause. If it were, Kahuana and others like him (no offense - I like speed and Rockets and horsepower, and the whole shebang too) would have all experienced similar fates. And un-balanced -3, -4 and -6 rudders would be fluttering all over the place at the mere hint of exceeding Vne (and they don't seem to be).
Again there were certainly other causitive factors - ham-footed rudder excursions, exposed balance horns to high (Vne++) aerodynamic loads, out of balance flight, reduced structural margins (maybe due to the rudder trim tab), flight through wake turbulence, to name a likely few.
And yes it does relate to the movement for improved safety under current discussion. This low time pilot, God rest his soul, went into a far corner of the envelope on little more than a whim. That is not good headwork. It is something we are all capable of doing. We must promote an atmosphere where that kind of excursion is less likely to happen.
This death was preventable.
__________________
Gary Reed
RV-6 IO-360
WW 200 RV now an Al Hartzell for improved CG
Last edited by gereed75 : 05-19-2011 at 02:44 PM.
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05-19-2011, 02:46 PM
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Join Date: May 2007
Location: Quincy, Florida
Posts: 680
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agree
I agree 100% with Bill Near's comments. Every decision we make flying our airplanes adversley effects others if our decision is a bad one.
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05-19-2011, 02:52 PM
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Join Date: Dec 2006
Location: Sumner, WA
Posts: 722
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I too felt relieved when reading the report. Not because I never make mistakes but just knowing there was a lot more to the story than flying along and having your tail come off.
__________________
Jeff Bloomquist
Sumner, WA
PP-ASEL, IR
RV-7A
Flying
1150 Hours
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05-19-2011, 02:52 PM
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Join Date: Jan 2005
Location: Chandler, AZ
Posts: 2,904
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Missed it.
Quote:
Originally Posted by Jamie
The report was quite clear in this regard.
Top of page 4:
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Thanks Jamie, I missed that somehow.
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Darwin N. Barrie
Chandler AZ
www.JDair.com
RV-7 N717EE-Flying (Sold)
RV-7 N717AZ Flying, in paint
EMS Bell 407,
Eurocopter 350 A-Star Driver
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