Uncontrolled Loops Elevator failure

Don’t give up, keep evaluating. Find the answer. This is important.

R

On Friday, September 28, 2018 at 6:50:58 PM UTC-4, Retting wrote:
Don’t give up, keep evaluating. Find the answer. This is important.

R

If the stick was full back(it may not have been), the loop would be tight enough that it would not seem like the second, or third, would have been at a much greater speed.
I've done enough loops in high performance gliders to know that if you don't relieve the pressure a bit at the beginning of the down portion you run out of energy on the following up portion.
I wonder if this was a spiral that looked like loops from the point of observation. In a spiral the speed will increase and loads will rise until failure.
It is very possible nobody was flying due to GLOC.
FWIW
UH

That seems plausible. An inclined spiral may look like a loop without robbing all the energy at the top. It is hard to imagine a jammed elevator control situation that would result in continuous loops that didn’t end with a stall at the top rather than over-g at the bottom. Worth spending some time to think about the dynamics of a full-aft stick versus witness accounts. They may not line up exactly right.

If the witness accounts are remotely accurate G-LOC would be plausible as well.

An awful mystery.

Andy Blackburn
9B

Not that is adds to the discussion, but by my count there have been 7 Nimbus 4D’s that have suffered spin/spiral wings break off.
The owner of a local N4D replace a metal bracket thingy in the elevator assembly on his 18 year old glider, it was the same part number for a
Dou discus and Arcus. Lots of common parts in the tail feathers of all twin place S-H gliders. Sure would be nice to know failure mode.

To add to the possibilities. In Denmark we've had a couple of cases of poor welding joints.
One Arcus had the air brake triangle coupling to the fuselage horn fail due to poor welding quality on top of the triangle being poorly designed. The pilot got in control of the plane by pulling the other brake and landed safely. After this it turned out SH didn't know whether the right triangles were installed in our Duo. They'd been mixed up between Duo's and Arcus's and apparently they're different.
Another Duo Xlt had the airbrake pushrod separate in the fuselage due to poor welding. This didn't result in an AD.
To a worrying extent the the learning feedback in European aviation is malfunctioning. The authorities are the ones supposed to address this.

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.

All of this horribleness points to one particular conclusion in my mind. Personal parachutes are not a satisfactory solution in way too many situations. We need to have whole aircraft chutes -- period. I think in most of these cases, actual and speculated, there would have been opportunity to activate a whole aircraft system.

All of the manufacturers need to get on the ball. GP gliders is now doing it. I have a whole aircraft system in my Lambada. I feel safer because of it. There have been at least two saves in Lambadas alone.

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?