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4th Aug 2018 Junkers JU52 crashed in Switzerland

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4th Aug 2018 Junkers JU52 crashed in Switzerland

Old 7th Aug 2018, 02:31
  #121 (permalink)  
 
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Density altitude as KK says well above... think.maybe rotor effect too. iOW staggering about unknowingly far too near a stall and turning such a large span effectively downwind.
In some aviation circles, theres a term called 'tip stall' where the inner tip in a turn drags back and drops.
Unless a wing engine did just 'let go' which will likely be discovered if so...
So tragic... indeed, fate is the hunter.
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Old 7th Aug 2018, 06:42
  #122 (permalink)  
 
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Is there anybody here who has actually flown a Junkers with the "Doppelflügel" (Double Wing) aileron desgn? Like the Ju 52, T 29 or the Ju 86? It is a quite unique design with a fixed main wing and a smaller, moveable wing trailing the main wing which acts as flap and control surface. How efficient is it at low speed? Does it tend to reverse close to stall? Does it produce significant adverse yaw?
The Ju 52 has a relatively highly tapered wing and small ailerons, how forgiving is it close to stall?

There probably is a reason why this design disappeared post WWII.... And probably the end of Junkers is not the only one, as many other design features of german manufacturers were picked up by the aviation world.

Does anybody know the elevator trim system of the Ju 52? When hearing about the sudden dive, alaska air trim actuator failure comes to mind. First dive recovered, second dive fatal.
As BAZL does allow the Junkers to fly again, obviously they have ruled out technical failure already ?

When talking low density altitude, higher stall speed is only one aspect. What I found more remakable, especially in the mountains, is that the radius of any turn also increases significantly. You simply need more space to maneurve if the density altitude is high. Typically you do not notice this, but in the mountains it is a different story.
So you have 3 adverse factors: Higher stall speed, less engine power and less space to maneurve. Might be one too much...
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Old 7th Aug 2018, 06:49
  #123 (permalink)  
 
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Just for clarification: BAZL has never stopped the Ju 52 from flying. So no need for some permission to fly again.
Ju Air has only paused it's own flights until I think mid august.
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Old 7th Aug 2018, 07:08
  #124 (permalink)  
 
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Originally Posted by Volume View Post
What I found more remakable, especially in the mountains, is that the radius of any turn also increases significantly. You simply need more space to maneurve if the density altitude is high.
Not surprising. Your true speed is faster in less dense air. But as long as you fly IAS that should not be a big factor. Compared to higher performance planes you can still turn on a dime with that slow bird. I would be surprised if the PF did deliberately accelerated manoeuvres with a load of paying customers.
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Old 7th Aug 2018, 07:58
  #125 (permalink)  
 
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Originally Posted by Alpine Flyer View Post
An undated (and probably reprinted) factory sales brochure for the Ju52/3m lists the following data:

1980hp total for 3 BMW 132A engines

service ceiling 19030ft (20350 with variable pitch props), OEI 9520ft (10830 with variable pitch props)
(Can't tell from online pics whether props are variable or fixed pitch, looks more like the latter and absence of manifold pressure gauges on flight deck pics would also hint at that.)

MTOM 10t (22000lb.)
The Ju-Air homepage states max continuous 500 per engine, so 1500 hp total. MTOW is 10 t which gives 6.6kg per hp. The oldest version of a C172 had 145 hp on roughly 1000 kg MTOW, so the power to weight ratio is more or less the same! And then, Mr. Junkers designed a load carrier, not a sleak performer. The JU-52 is a drag queen. The very crew of the perished aircraft commented to that fact a couple of years ago in an aviation journal. The factory specs are irrelevant, they were issued during the Third Reich where engines were dispensable and propaganda important. Nowadays, an overhaul of a BMW radial leads to prohibitive cost for a non-profit operator. Though the homepage of JU-Air says the power is reduced due to noise considerations, but I think going easy on these motors is the real reason for reducing max. continuous. Some people quote also that the engines were modified to run on leadless Mogas. Now its anybodies own guess to what altitude you can climb with such a ship with a full passenger load on a hot day.
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Old 7th Aug 2018, 08:00
  #126 (permalink)  
 
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May well not be at all relevant to the subject of this thread but on the subject of mountain flying it is widely believed that the experienced captain in this accident thought they could out climb a slope ...and failing that thought they could turn inside a valley...

https://aviation-safety.net/database...?id=20031217-0
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Old 7th Aug 2018, 08:37
  #127 (permalink)  
 
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Originally Posted by EDLB View Post


Not surprising. Your true speed is faster in less dense air. But as long as you fly IAS that should not be a big factor. Compared to higher performance planes you can still turn on a dime with that slow bird. I would be surprised if the PF did deliberately accelerated manoeuvres with a load of paying customers.
Alll very true... but from what Ive noticed, IAS and turn rate when well away from ground rarely leads to stalls. Turning in close sight of ground and where wind gradient may exist is different... this is the regime of low speed and low altitude flight, and tight turns in gradient winds... gliding, microlighting etc.

Last edited by HarryMann; 7th Aug 2018 at 13:32. Reason: Meaning wrong.. re phrased
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Old 7th Aug 2018, 09:02
  #128 (permalink)  
fdr
 
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Sad end to an old lady and the occupants.

The photo geometry may be adding some foreshortening, but the aircraft would appear to be in a relatively nose high attitude. The attitude itself is not indicative of AoA, except that where there is limited performance, there is not too much opportunity to trade "speed for height". If any video survived the event, then it may be able to reconstruct the speed using broadband noise SPL, there is substantial airflow noise on these types of aircraft. Any engine faults may also be detected through video with a spectral analysis. The choices of causation for a steep flight path impact in clear weather are fairly limited, and will be able to be determined from the wreckage that remains. The State investigators will do a comprehensive analysis, and will most likely determine the probable cause of the accident.

Operating limited performance aircraft in rugged terrain can be challenging, even without other factors stressing the op. I for one would hate to see excessive regulatory response to the operation of the older aircraft types, they provide an insight into where we have been and thereby give some meaning to where we are. There is inherent risk, but then we dont get out of life alive, and we are here for the experience.

RIP to all on board.

PS, I still fly some WWII aircraft, and others around the Korean war vintage. They are different, exude character, but they are different.
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Old 7th Aug 2018, 09:32
  #129 (permalink)  
 
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I have a few hundred hours on the JU52. "Volume" asked about the elevator trim. The large elevator trim wheel has a selector to enable it to also wind down the flaps. I found the aircraft very forgiving and there was nothing unusual about the stall. We really have to allow the investigators to do their part in finding out what happenned to this remarkable aircraft.
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Old 7th Aug 2018, 09:50
  #130 (permalink)  
 
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"smoke" looks like grass to me



I think that this may be a better version of the image. Image is 790x444, make your browser wide enough for best view.

For the "smoke" to be such a wide trail at the aircraft a large fire would seem to be necessary. There is no sign of fire at the crash site.

Grass, not smoke.

This is still a very poor image, 20k jpeg. Someone may well have a better one.

Source -
"https://www.srf.ch/var/storage/images/_aliases/944w/auftritte/news/bilder/2018/08/05/node_16198592/178592648-2-ger-DE/bild.jpg"

Last edited by jimjim1; 7th Aug 2018 at 14:13.
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Old 7th Aug 2018, 10:39
  #131 (permalink)  
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Piz Segnas
This is a picture of the area in wintertime, the right summit is Piz Segnas. The sunny snowfield left of Piz Segnas has the same appearance as the "smoketrail" in the pic with the JU.

skadi
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Old 7th Aug 2018, 11:03
  #132 (permalink)  
 
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Cover of the PDF,

Not the first time in this place!

https://www.ju-air.ch/app/download/7...zette-2018.pdf
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Old 7th Aug 2018, 12:08
  #133 (permalink)  
sir
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Originally Posted by skadi View Post

Piz Segnas
This is a picture of the area in wintertime, the right summit is Piz Segnas. The sunny snowfield left of Piz Segnas has the same appearance as the "smoketrail" in the pic with the JU.

skadi
I agree. I think this view is Segnas from the Glarus side of the ridge, the Tschingelhörner would be to the right of this picture. This would be consistent with the claim the photo of the aircraft with ‚smoke trail‘ was taken in Chamm, Glarus and that is categorically not an image of the accident. The accident occurred on the other side of the ridge on the Graubünden side.
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Old 7th Aug 2018, 12:13
  #134 (permalink)  
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Originally Posted by sir View Post
I agree. I think this view is Segnas from the Glarus side of the ridge, the Tschingelhörner would be to the right of this picture. This would be consistent with the claim the photo of the aircraft with ‚smoke trail‘ was taken in Chamm, Glarus and that is categorically not an image of the accident. The accident occurred on the other side of the ridge on the Graubünden side.

I think, the lowest part of the ridgeline in the very right part of the Pic must be the Segnas Pass, so the crashsite is just behind.

skadi
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Old 7th Aug 2018, 12:25
  #135 (permalink)  
sir
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Originally Posted by skadi View Post
I think, the lowest part of the ridgeline in the very right part of the Pic must be the Segnas Pass, so the crashsite is just behind.

skadi
Agreed, the Hüttenwart (lodge keeper) at the Segnashütte said in his interview that the aircraft began a left turn before falling - for me a left turn would mean towards the pass / ridge as if attempting to make the crossing. No idea how close to the Tschingelhörner ridge side they flew though as they headed up that valley.
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Old 7th Aug 2018, 12:41
  #136 (permalink)  
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Originally Posted by sir View Post
Agreed, the Hüttenwart (lodge keeper) at the Segnashütte said in his interview that the aircraft began a left turn before falling - for me a left turn would mean towards the pass / ridge as if attempting to make the crossing. No idea how close to the Tschingelhörner ridge side they flew though as they headed up that valley.
The Hüttenwart stated in another interview that he was inside the lodge and didn't see the crash personally, but others did. So the upcoming report will definitely give some information of the flightpath short before the accident.

skadi
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Old 7th Aug 2018, 12:46
  #137 (permalink)  
 
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The limits of the accident photograph are as shown by my red box, ok the point of perspective is more to the right in the first but the same profiles are present.
You can clearly see the feature that appears to be smoke as a ridgeline.
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Old 7th Aug 2018, 12:53
  #138 (permalink)  
 
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Indeed. It's just grass. No smoke whatsoever.

[QUOTE=jimjim1;10217091]

I think that this may be a better version of the image.
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Old 7th Aug 2018, 14:52
  #139 (permalink)  
 
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But nevertheless a quite nose-up pitch for the old lady not currently climbing...
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Old 7th Aug 2018, 15:19
  #140 (permalink)  
 
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Does anyone know if the Martinsloch itself causes any odd wind phenomena? I came across a blog where someone walked/climbed to the Martinsloch and said (translated from German): "A poisonous cold wind blew through the impressive 19 × 17 meter hole. "
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