Uncontrolled Loops Elevator failure

Le samedi 29 septembre 2018 17:45:07 UTC+2, Nick Kennedy a écritÂ*:
A couple of observations from the cheap seats:
It sure looks like to me over the years there have been way too many Shempp Hirth Open class gliders going in; now with a latest rash of two seat motor equipped ships losing control and coming apart in the air for no obvious reason.
I have NO faith in the NTSB getting to the bottom of any of this. AFAIK the Nephi Arcus fuselage is still in the forest up by Monroe Peak Ut. I thought a loss of control surfaces was a major red flag and cause for a real investigation. Kinda hard to do a investigation when the fuselage after 3 months is still in the woods.
Concerning the Glider Bob Saunders Stemme NTSB investigation and final report,I found to be shallow and half assed at best. I never went to the crash sight, I wish I had now, to look at it with my own eyes to see what really happened. See where the engine switch's were and the engine controls etc etc.
Jonathan stated he knows of 7,7!! Nimbus 4's that have had the wings come off in flight, Holy S*%#t that's a lot!
These gliders we fly are built and stressed tested to take huge loads and most of the time do quite well; why are some coming apart? Design defects? FOD? Poor Maintenance, incorrect assembly, poor piloting skills? All of the above?
Or are all these accidents just the actual statistical odds catching up to us?
I wonder as several of these ships have obviously had control failures. And that is a tough nut to swallow. If I thought there was any history of my LS3a failing me I would not fly it, period. But people continue to fly those 2 place Shempp Hirth ships with and without motors, god bless them, they are braver than me! But this point I would not climb in one, but that's just me, there I said it. Something is obviously screwed up in those planes..
Keep the rubber side down and the shiny side up.

In any open class two-seater, once you've done a full turn in a spin, you are very likely to lose your wings.
The angular momentum of these wings plus the fuselage is about 4 times higher than that of a 15 m ship, but the rudder is only twice as large - so it will take more twice the time to stop the rotation, all the while accelerating vertically. Little chance *not* to exceed vne.

If the fuselage bows down under positive G's, that would reduce the declanage and therefore reduce the up elevator requested. If the pilot is looking at rocks and trees where the blue sky should be on his canopy, he's going to pull even harder to make the rocks go away. More bowing down reduces the angle of the horizontal stab even more and reduces the requested up elevator. Is this the reason these big ships end up going so fast? He's pulling back, but the ships going faster and faster and soon the wings start bowing up. I remember flying with the Chase 101 (no composite structure, solid foam wings with glass covering) the pilot got into a spiral dive and the wings bowed up in a big U...........sound familiar? Anyway, the pilot bailed out and later reported that the ailerons wouldn't roll him out of the spiral. Think about it, they're little more tip rudders when in the vertical position. Our composite toys are quite flexible structures, I watched a Discus land in a barley field, he touched down about 40 knots, caught his left wing in the barley and spun around. The fuselage bowed like a banana and the T tail laid over about 45 degrees. The ship came to an abrupt stop at about 180 degrees and the T tail snapped back up to vertical and just sat there and quivered for second or two! I don't have to worry too much about all this because my Genesis doesn't have a boom, but it does have a ballistic parachute! If I were still flying a big ship, I'd make damned sure one of us had his head out of the cockpit AT ALL TIMES!
My, how I have rambled on, sorry.
JJ

On 09/29/2018 09:45 AM, Nick Kennedy wrote:
A couple of observations from the cheap seats:
It sure looks like to me over the years there have been way too many Shempp Hirth Open class gliders going in; now with a latest rash of two seat motor equipped ships losing control and coming apart in the air for no obvious reason.
I have NO faith in the NTSB getting to the bottom of any of this. AFAIK the Nephi Arcus fuselage is still in the forest up by Monroe Peak Ut. I thought a loss of control surfaces was a major red flag and cause for a real investigation. Kinda hard to do a investigation when the fuselage after 3 months is still in the woods.
Concerning the Glider Bob Saunders Stemme NTSB investigation and final report,I found to be shallow and half assed at best. I never went to the crash sight, I wish I had now, to look at it with my own eyes to see what really happened. See where the engine switch's were and the engine controls etc etc.
Jonathan stated he knows of 7,7!! Nimbus 4's that have had the wings come off in flight, Holy S*%#t that's a lot!
These gliders we fly are built and stressed tested to take huge loads and most of the time do quite well; why are some coming apart? Design defects? FOD? Poor Maintenance, incorrect assembly, poor piloting skills? All of the above?
Or are all these accidents just the actual statistical odds catching up to us?
I wonder as several of these ships have obviously had control failures. And that is a tough nut to swallow. If I thought there was any history of my LS3a failing me I would not fly it, period. But people continue to fly those 2 place Shempp Hirth ships with and without motors, god bless them, they are braver than me! But this point I would not climb in one, but that's just me, there I said it. Something is obviously screwed up in those planes.
Keep the rubber side down and the shiny side up.


The NTSB prelim said the wreckage debris field from Nephi was about a
mile long and taken to a secure facility for analysis. I assume this
includes the fuselage?

On Saturday, September 29, 2018 at 8:45:07 AM UTC-7, Nick Kennedy wrote:
A couple of observations from the cheap seats:
It sure looks like to me over the years there have been way too many Shempp Hirth Open class gliders going in; now with a latest rash of two seat motor equipped ships losing control and coming apart in the air for no obvious reason.
I have NO faith in the NTSB getting to the bottom of any of this. AFAIK the Nephi Arcus fuselage is still in the forest up by Monroe Peak Ut. I thought a loss of control surfaces was a major red flag and cause for a real investigation. Kinda hard to do a investigation when the fuselage after 3 months is still in the woods.
Concerning the Glider Bob Saunders Stemme NTSB investigation and final report,I found to be shallow and half assed at best. I never went to the crash sight, I wish I had now, to look at it with my own eyes to see what really happened. See where the engine switch's were and the engine controls etc etc.
Jonathan stated he knows of 7,7!! Nimbus 4's that have had the wings come off in flight, Holy S*%#t that's a lot!
These gliders we fly are built and stressed tested to take huge loads and most of the time do quite well; why are some coming apart? Design defects? FOD? Poor Maintenance, incorrect assembly, poor piloting skills? All of the above?
Or are all these accidents just the actual statistical odds catching up to us?
I wonder as several of these ships have obviously had control failures. And that is a tough nut to swallow. If I thought there was any history of my LS3a failing me I would not fly it, period. But people continue to fly those 2 place Shempp Hirth ships with and without motors, god bless them, they are braver than me! But this point I would not climb in one, but that's just me, there I said it. Something is obviously screwed up in those planes..
Keep the rubber side down and the shiny side up.

Just wanted to say, in almost 1700 hours of glider time, I have about 400 hours in s single seat N4 and about 100 in two different N4D's, one motor one pure sailplane. The hours in these long wingers are the most pleasant of my soaring career, especially the two place nimbus 4D. These aircraft are not easy to fly, but they fly magnificently! Have never flown 21 or 23 meters, but the 26.5 meter birds can efficiently dolphin fly for hundreds of kilometers, something you just can't do in a std, 15m or 18m bird. Plus they are graceful and beautiful, but a bit of inattention can leave dwindling options. They are like dating a super model, I imagine.