Accident in Namibia, SH Ventus 2cxm

The news of the crash in Namibia on the 11th January 2016 was published yesterday.
http://www.republikein.com.na/ongelu...r-lodge.262951

Summary in English:
A French couple bailed out of a Nimbus 4DM (German registered D-KCTI) near the Bitterwasser Lodge, on the 11th January 2016 at 15:40 UTC (16:40 local).

According to the report the left wing dropped while thermalling and recovery was not possible. My assumption is that this was another Nimbus 4 in flight break up during spin recovery.

The 65 year old male sustained minor injuries while the 60 year old woman suffered no injuries. They managed to bail out at about 700 meters AGL.

"My assumption is that this was another Nimbus 4 in flight break up during spin recovery."

How many of these have there been?

Boggs

Le vendredi 15 janvier 2016 16:12:36 UTC+1, Waveguru a écrit*:
"My assumption is that this was another Nimbus 4 in flight break up during spin recovery."

How many of these have there been?

Boggs

Some. Spiral dives and spins with 25m+ gliders go with a huge chance of not being able to recover inside the flight enveloppe. The moment of inertia of these gliders are massively higher than with a 15m/18m glider. They take longer time to stop the rotation, while airspeed increases very rapidly.

Bert
Ventus cM ZW

How can they get certification if they come apart recovering from a spin?

Boggs

Le vendredi 15 janvier 2016 17:44:12 UTC+1, Waveguru a écrit*:
How can they get certification if they come apart recovering from a spin?

Boggs

You can recover from a spin, but you'd need to be sharp. You miss a beat, you'll loose a wing.
Not sure whether a glider 25 m is required to undergo spin testing for certification.

On Sunday, January 3, 2016 at 3:39:58 PM UTC-5, smfidler wrote:
http://www.az.com.na/unf-lle/schweiz...ngl-ckt.428806

25 m certification; I would chance a guess that the spin recovery
test is done by a very experienced (possibly test) pilot.

John F

An old, no longer bold pilot.

Actually my Nimbus 4 was an honest spinner. Once while thermaling in a valley very close to the moutons a gust tried to get a spin developed, normal recovery. Prior to this I had done a number to spin entries followed by normal recovery. I never let a spin develop as i would not in normal flying either. There is a wait time while you wait for a control surface to dig in, but all in all I thought it was honest a normal. I also have several hundred hours in a Nimbus 4D. I found the 4D flew considerabily different than the single seat Nimbus 4.

The rigging is very important on a Nimbus and when I first got mine is was rigged horribly and flew horribly. Fixed the rigging and it was a beauty to fly.

On Friday, January 15, 2016 at 9:01:21 AM UTC-8, Tango Whisky wrote:
Le vendredi 15 janvier 2016 17:44:12 UTC+1, Waveguru a écrit*:
How can they get certification if they come apart recovering from a spin?

Boggs

You can recover from a spin, but you'd need to be sharp. You miss a beat, you'll loose a wing.
Not sure whether a glider 25 m is required to undergo spin testing for certification.

Just like any other certified glider according to the European CS-22 norm, a 25+ m glider has to undergo successful spin tests, including tests with asymmetrical water ballast. That's how the Eta glider used for certification broke up some years ago: when getting out of a spin with full ballast in one wing, the other empty, the fuselage couldn't resist the torsional load and failed.

Excerpt from the CS-22 rules:

Spinning

CS 22.221 General

(a) Compliance with the following requirements must be shown in all configurations and, for a powered sailplane, with the engine idling. For sailplanes equipped to carry water ballast, the demonstrations of sub-paragraphs (b) to (g) must also be made for the most critical water ballast asymmetry that might occur due to any single malfunction or due to lateral accelerations during a spin.

(b) The sailplane must be able to recover from spins of at least five turns or such lesser number at which the spin changes into a spiral dive, by applying the controls in a manner normal for recovery and without exceeding either the limiting air-speed nor the limiting positive manoeuvring load factor for the sailplane. Tests must be conducted with wing-flaps and airbrakes neutral (see AMC 22.335) and with:
(1) controls held in the position normal for spins;
(2) ailerons and rudder used in opposite directions;
(3) ailerons applied in the direction of rotation.
In addition and where applicable, tests must be conducted in critical combinations of airbrake extension, wing-flap deflection, waterballast including trim water-ballast and with the powerplant extended or retracted. For wing-flap positions for which a VFE limitation is established, the flap position may be adjusted during recovery after the auto-rotation has stopped. (See AMC 22.221 (b))

(c) A sailplane, in the configurations certificated for intentional spinning, must be able to recover from any point in a spin as defined in CS 22.221(b) in not more than one additional turn. In those configurations not approved for intentional spinning, sub-paragraph (d) must be applied. (See AMC 22.221 (c), (d), (e) and (f))

(d) A sailplane in the configurations not certificated for intentional spinning, must still be able to recover from a spin as defined in CS 22.221(b) in not more than one and a half additional turns. (See AMC 22.221 (c), (d), (e) and (f))

(e) In addition, any sailplane must be able to recover from a one turn spin in any configuration in not more than one additional turn. (See AMC 22.221 (c), (d), (e) and (f))

(f) The loss of altitude from the point at which recovery is initiated to the point at which horizontal flight is first regained must be determined in all of the above mentioned cases. (See AMC 22.221 (c), (d), (e) and (f))

(g) It must be impossible to obtain uncontrollable spins with any use of the controls.

CS 22.223 Spiral dive characteristics
If there is any tendency for the spin to turn into a spiral dive the stage at which this tendency occurs, must be determined. It must be possible to recover from the condition without exceeding either the limiting air speed or the limiting positive maneuvering factor for the sailplane. Compliance with this requirement must be shown without the use of air brakes.

Curiously enough the ASH-26E is not certified for spins.


On Friday, January 15, 2016 at 1:51:30 PM UTC-8, wrote:
Just like any other certified glider according to the European CS-22 norm, a 25+ m glider has to undergo successful spin tests, including tests with asymmetrical water ballast. That's how the Eta glider used for certification broke up some years ago: when getting out of a spin with full ballast in one wing, the other empty, the fuselage couldn't resist the torsional load and failed.

Excerpt from the CS-22 rules:

Spinning

CS 22.221 General

(a) Compliance with the following requirements must be shown in all configurations and, for a powered sailplane, with the engine idling. For sailplanes equipped to carry water ballast, the demonstrations of sub-paragraphs (b) to (g) must also be made for the most critical water ballast asymmetry that might occur due to any single malfunction or due to lateral accelerations during a spin.

(b) The sailplane must be able to recover from spins of at least five turns or such lesser number at which the spin changes into a spiral dive, by applying the controls in a manner normal for recovery and without exceeding either the limiting air-speed nor the limiting positive manoeuvring load factor for the sailplane. Tests must be conducted with wing-flaps and airbrakes neutral (see AMC 22.335) and with:
(1) controls held in the position normal for spins;
(2) ailerons and rudder used in opposite directions;
(3) ailerons applied in the direction of rotation.
In addition and where applicable, tests must be conducted in critical combinations of airbrake extension, wing-flap deflection, waterballast including trim water-ballast and with the powerplant extended or retracted. For wing-flap positions for which a VFE limitation is established, the flap position may be adjusted during recovery after the auto-rotation has stopped. (See AMC 22.221 (b))

(c) A sailplane, in the configurations certificated for intentional spinning, must be able to recover from any point in a spin as defined in CS 22.221(b) in not more than one additional turn. In those configurations not approved for intentional spinning, sub-paragraph (d) must be applied. (See AMC 22.221 (c), (d), (e) and (f))

(d) A sailplane in the configurations not certificated for intentional spinning, must still be able to recover from a spin as defined in CS 22.221(b) in not more than one and a half additional turns. (See AMC 22.221 (c), (d), (e) and (f))

(e) In addition, any sailplane must be able to recover from a one turn spin in any configuration in not more than one additional turn. (See AMC 22.221 (c), (d), (e) and (f))

(f) The loss of altitude from the point at which recovery is initiated to the point at which horizontal flight is first regained must be determined in all of the above mentioned cases. (See AMC 22.221 (c), (d), (e) and (f))

(g) It must be impossible to obtain uncontrollable spins with any use of the controls.

CS 22.223 Spiral dive characteristics
If there is any tendency for the spin to turn into a spiral dive the stage at which this tendency occurs, must be determined. It must be possible to recover from the condition without exceeding either the limiting air speed or the limiting positive maneuvering factor for the sailplane. Compliance with this requirement must be shown without the use of air brakes.

On Friday, January 15, 2016 at 1:58:38 PM UTC-8, Jonathan St. Cloud wrote:
Curiously enough the ASH-26E is not certified for spins.

And the reason for that would be, what in Aviation is known as common sense. You want engine oil spilling over a possibly warm/hot exhaust? An engine bay fire?

The ASH-26E handles beautifully, I expect it to recover from a spin very well. Certainly all pushing I have done both with and without an engine installed, it was just great.