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  #51  
Old 06-03-2013, 09:11 AM
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smokyray smokyray is offline
 
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Default CFIT...

Quote:
Originally Posted by Jamie View Post
I am dissatisfied with the report. I'm not saying that the final conclusion from the report was wrong, but that the information made available to the public was shallow and useless -- the entire point of these reports is to improve safety
Jamie,
It's always tough reading reports after the fact, especially when it's a bro, it never gets any easier. Imagine burying 14 of your bros over a 25 year career, combat and training, many of them "CFIT inconclusive".In this case the report lends a classic "stall/spin" scenario or as they say, "controlled flight into terrain" CFIT.

Having spun numerous RV's and having spun several RV7's at various CG's, the spin entry and recovery is very straightforward even if inadvertently entered. Unusual attitude training and spin recovery is something everyone should practice or at least have demonstrated. Regardless of what they were doing or what happened, the end result was the same.

Lesson? Vigilance: Fly the @#$% Airplane, all the time...

V/R
Smokey

Last edited by smokyray : 06-03-2013 at 09:21 AM.
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  #52  
Old 06-03-2013, 09:30 AM
sandifer sandifer is offline
 
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Quote:
Originally Posted by Brantel View Post
What would cause a pilot with this experience level in a RV end up in such a spin?
There can be many reasons, including letting passengers fly. This is not intended as speculation on the accident pilot's experience, but ending up in a spin is not the biggest issue. Recovering from the spin is the biggest issue. Even experienced aerobatic pilots can occasionally depart controlled flight if trying something new. That alone is not a problem. Spin recovery experience is all that matters when one finds themselves in an accidental spin.

A pilot can have lots of experience flying, and even lots of experience doing aerobatics, but if they do not have significant experience (and currency) with emergency spin recovery in all spin modes, they can possibly become a statistic. Many experienced aerobatic pilots have died after failing to recover unusual spin modes. Most have been a result of confusion and improper inputs. If not experienced and current with emergency spin recovery from all spin modes, a lifetime of flying will do little to prepare a pilot for an encounter with an accidental and/or unusual spin mode.

Last edited by sandifer : 06-03-2013 at 03:17 PM.
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  #53  
Old 06-03-2013, 06:49 PM
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Called AFS...the slip value is acceleration-derived; the unit is G, not degrees.
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  #54  
Old 06-03-2013, 09:42 PM
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rocketbob rocketbob is offline
 
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Originally Posted by cguarino View Post
At -60 degrees pitch the aircraft is a .5g until you pull on the stick. Then the g load will increase as you pull the stick until an accelerated stall. What do you mean you can't pull 2.4gs at -60 degrees?
Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
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  #55  
Old 06-03-2013, 11:25 PM
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Quote:
Originally Posted by rocketbob View Post
Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
No, but maybe the plane could have started a dive *before* the data point was recorded, and been in the process of pulling out of a dive (nose 60 degrees below the horizon, upright) when the data point was logged?
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  #56  
Old 06-04-2013, 01:05 AM
Mounz Mounz is offline
 
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@ Rocket Bob - pitch has no relevance as to the amount of g you can pull. Check the data again and you will notice that the aircraft was basically vertically banked in a nose down (-60degrees) attitude. All you have to do is haul the stick into your gut and - voila you will pull g. Try it in your borrowed 6. Consider the aircraft skidding and the airspeed increasing in this nose down knife-edged dive and the sustained g seems to support the accelerated deep stall theory. I would suggest you try this manoeuvre with plenty of altitude to spare! Possibly simply unloading the aircraft and taking the feet off the pedals may have had it flying again. It's just so easy to speculate from the comfort of an armchair.
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  #57  
Old 06-04-2013, 01:33 AM
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John Clark John Clark is offline
 
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Quote:
Originally Posted by Mounz View Post
Possibly simply unloading the aircraft and taking the feet off the pedals may have had it flying again. It's just so easy to speculate from the comfort of an armchair.
Looking at the data, I see the same scenario. A common, but very wrong, reaction to a spin is full up elevator because the airplane is descending, and rudder to fight the rotation. just releasing the back pressure can cure the problem, but without training it is counter intuitive to relax the back pressure, let alone push forward when the earth is rushing toward you. And yes, this opinion is coming from the comfort of a ground bound chair.

John Clark ATP, CFI
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  #58  
Old 06-04-2013, 02:56 AM
scsmith scsmith is offline
 
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Default slip in 'g's

Quote:
Originally Posted by DanH View Post
Called AFS...the slip value is acceleration-derived; the unit is G, not degrees.
I was lying in bed thinking about it, and this is exactly what occurred to me. No beta-vane, they must be measuring slip as a lateral component of the gravity vector. Thanks Dan for confirming.

Two tenths of a g lateral acceleration......that's a spin.

The normal-acceleration varies between 1 g and 2.4 g's during the time there is so much lateral acceleration. This suggests a rather dynamic flight situation, such as the early stages of an evolving spin, where the spin axis is not vertical yet. The nose may be oscillating between -90 and -30 in pitch, with the sparse data sampling happening to catch a -60 on the way up (2.4 g) and then again on the way down (1 g). Admittedly, this last paragraph is speculative, but it does seem to reconcile with the available data.
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  #59  
Old 06-04-2013, 06:36 AM
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N355DW N355DW is offline
 
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I can't speak to the spin characteristics of an RV as I have never spun one, but the nose oscillating between vertical and maybe 30-40 degrees below the horizon is very typical of a spin in all other types of planes I have spun. At even points in the spin (1 turn, 2 turns, 3 turns, etc) your nose will be the high point, at the half points you will be closest to vertical. At the quarter turns you will appear to be yawed in reference to straight down, and the attitude halfway between vertical and the highest point. That is why competition pilots will prefer a 1&1/2 turn spin in a freestyle sequence, it allows the easiest transition to drawing a straight vertical line after the spin.

So if the characteristics of an RV are similar, I suspect a power on spin at low altitude is a good bet in this case.
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  #60  
Old 06-04-2013, 07:06 AM
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skylor skylor is offline
 
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Quote:
Originally Posted by rocketbob View Post
Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
Bob,

Here is some data from a test scenario that I flew last night for you to ponder:



Note the increasing negative (nose down) pitch while pulling over 3 g's...

Skylor
RV-8 N808SJ
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