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big saab gripen crash

Old 09-18-2016, 07:09 AM
  #26  
Jgwright
 
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In english he said that "of course it is with an aviation certificate so that the certificate is for the pilot and also for the plane. So that there are a lot of steps while building and test flying the aircraft". Sorry my assumption was that it was a German Large Model Certification.


John
Old 09-18-2016, 02:02 PM
  #27  
cmp3cantrj
 
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Originally Posted by Jgwright View Post
A comparison with the Mosquito is not really a good one. This had a balsa core sandwiched between 2 ply sheets and was a composite structure.http://www.mosquitorestoration.com/gallery02.shtml The resulting fuselage half was a bit like a moulded canoe had great strength and did not need a large number of formers to stiffen it. Also look at the shot of the rear bulkhead with the fin attached. Similar construction was used on several WW2 German jet aircraft with ply skins on a light core.


John
I didn't make a direct comparison with the Mosquito. I merely said that the Mosquito proves that wood is a perfectly acceptable material - in response to someone who had suggested that the simple fact that it was made of wood was to blame.
I wasn't implying any similarity between this model (or any model) and the Mosquito.

Of course what you do with the wood is critical - but then that is true of any material.

btw wood itself is the original "composite material!
Old 09-18-2016, 02:21 PM
  #28  
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Turbinator, boomerangs, are wood!!

jose
Old 09-18-2016, 04:06 PM
  #29  
pkoury
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Originally Posted by invertmast View Post
makes one reconsider the idea of a 1/10 XB-70 valkyrie they are designing....
Seems to me the weight limit might be a contributing cause of the crash. The bigger models built to attend the event may sacrifice proper construction in order to meet the weight limits. Of course even a properly designed and constructed aircraft an be overstressed by pilot error. Remember the Airbus that flew into wake turbulence and lost its vertical stabilizer when the pilot danced on the rudder and overstressed the structure.
Old 09-18-2016, 04:45 PM
  #30  
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Really bad structural design. You can tell by how slow it took off that it has very light wing loading, unrealistic for a model this size. It flew like a foamie, and died like a foamie.
Old 09-18-2016, 09:55 PM
  #31  
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No doubt that aviation authorities in countries this aircraft performed are watching this with a certain interest.

Merlin II
Old 09-19-2016, 12:35 AM
  #32  
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Never good when something crashes. How ever I really don't see the problem more then for the owner of the plane. As long as all planes are flown according to the safety regulations a crash like this are spectacular but never really dangerous.

Also this year they moved the net back at least 10meters more which gave much better clearance to the spectators. Much more comfortable when flying and handling the planes before and after flight. Previous years they used to land just behind your back when you were preparing for the flight.

The really dangerous big plane accident I know of was the B29 crashing. But I would not blame that on the airframe....
Old 09-19-2016, 12:39 AM
  #33  
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Yes, it is very regrettable when an incident like this occurs, it really puts us under the spot light for all the wrong reasons.

A further reminder to ensure we have all the safety measures in place at displays, club meetings ect, and demonstrate to all concerned we are doing what we say we are doing.
Old 09-19-2016, 01:11 AM
  #34  
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Never good when something crashes. How ever I really don't see the problem more then for the owner of the plane. As long as all planes are flown according to the safety regulations a crash like this are spectacular but never really dangerous.

The ONLY thing worth talking about here was the safe position it crashed in. I'm sure it will be looked at why it broke up.
Old 09-19-2016, 01:34 AM
  #35  
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As long as all planes are flown according to the safety regulations a crash like this are spectacular but never really dangerous.
I think the same way. In fact, I am sure that a smaller and certified, proven, top quality model plane built by a professional builder is much more dangerous if it is flown in a reckless way or in a inappropiate place.
Old 09-19-2016, 03:30 AM
  #36  
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Originally Posted by Dave Wilshere View Post
How ever I really don't see the problem more then for the owner of the plane.I'm sure it will be looked at why it broke up.
Yes correct, but the person that signed off the certificate of airworthiness and paperwork for or on behalf of the CAA must not be forgotten. I'm afraid he must not be a happy chap either. Bottomline is that something is learned from this, why it broke up and how such could be prevented.
Old 09-19-2016, 05:47 AM
  #37  
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The story got the attention of Popular Mechanics http://www.popularmechanics.com/flig...ks-up/?ref=yfp
Old 09-19-2016, 06:37 AM
  #38  
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Absolutely, the UK's LMA is paying for a seminar in November to help these examiners understand what is required during the inspection

Dave
Old 09-19-2016, 08:43 AM
  #39  
David Gladwin
 
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[QUOTE

The ONLY thing worth talking about here was the safe position it crashed in. I'm sure it will be looked at why it broke up.
[/QUOTE]

..........and that is exactly why I have raised the isssue, so many times including at JMA meetings, of too many pilots ignoring the CAA recommendations of 50 meters spacing, a runway width, between the model and other pilots etc. ( and the doubters should read CAP 658 and the advice on the BVM web. site)

Just saying that because we have had no serious crashes causing injury or worse then we are operating completely safely is hiding our heads in the sand. We MUST be more proactive than this if we are to secure the future of this hobby.

The UK full size air show scene had not had a fatal (spectator) accident since Farnborough with the 110 breakup over 50 years ago.(IIRC) Then came the Shoreham disaster, as a consequence of which the air show scene here has been changed dramatically, even the Red Arrows could not display at Farnborough. The preliminary AAIB report makes sobering reading.

If, God forbid, we do have a serious accident, there will always be those who will say someone should have spoken up BEFORE this happened. Well, I have, and we have to see what can be learnt from EVERY significant accident, or even incidents which could, in slightly different circumstances, have been much more serious accidents.

We learned this in military and airline aviation a long time ago. If we really value our privilege of being able to fly model jets with few restrictions and little interference from our regulators, the CAA in the UK, we need to follow their lead instead of just carrying on as we are and trusting to luck.

Last edited by David Gladwin; 09-19-2016 at 08:45 AM.
Old 09-19-2016, 11:38 AM
  #40  
cmp3cantrj
 
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Originally Posted by David Gladwin View Post


"The ONLY thing worth talking about here was the safe position it crashed in. I'm sure it will be looked at why it broke up."


..........and that is exactly why I have raised the isssue, so many times including at JMA meetings, of too many pilots ignoring the CAA recommendations of 50 meters spacing, a runway width, between the model and other pilots etc. ( and the doubters should read CAP 658 and the advice on the BVM web. site)

Just saying that because we have had no serious crashes causing injury or worse then we are operating completely safely is hiding our heads in the sand. We MUST be more proactive than this if we are to secure the future of this hobby.

The UK full size air show scene had not had a fatal (spectator) accident since Farnborough with the 110 breakup over 50 years ago.(IIRC) Then came the Shoreham disaster, as a consequence of which the air show scene here has been changed dramatically, even the Red Arrows could not display at Farnborough. The preliminary AAIB report makes sobering reading.

If, God forbid, we do have a serious accident, there will always be those who will say someone should have spoken up BEFORE this happened. Well, I have, and we have to see what can be learnt from EVERY significant accident, or even incidents which could, in slightly different circumstances, have been much more serious accidents.

We learned this in military and airline aviation a long time ago. If we really value our privilege of being able to fly model jets with few restrictions and little interference from our regulators, the CAA in the UK, we need to follow their lead instead of just carrying on as we are and trusting to luck.
Which is why the preface to the BMFA GTBA/JMA gas turbine safety rules emphasizes the following point:


Pay attention to where and when aircraft are flown to
ensure the safety of people, property and the environment.


However if you read the CAP and the BMFA handbook you will find that the 50 metres is measured to the crowd line or pit line - not to the pilots' box which may lie inside it.

CAP 658 says:
At least 50 m clear of persons, vessels, vehicles or structures. This can be reduced to 30 m for take-off or landing. Other model operators and any assistants or officials may be within this distance; as may vessels, vehicles or structures under their control

Last edited by cmp3cantrj; 09-19-2016 at 11:41 AM. Reason: typos
Old 09-19-2016, 12:22 PM
  #41  
dbsonic
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Watching this in slow motion, the amount of destruction from flight loads/pressure is astounding. I was trying to identify the the spar system on the wings after both wings departed, and aside from the short center rod or tube, there does not appear to be much of anything there.
Old 09-19-2016, 04:31 PM
  #42  
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Originally Posted by dbsonic View Post
Watching this in slow motion, the amount of destruction from flight loads/pressure is astounding. I was trying to identify the the spar system on the wings after both wings departed, and aside from the short center rod or tube, there does not appear to be much of anything there.
Definitely appears the be very little structural members in the wings. I noticed that there was one carbon tube spar that seems like it is pretty far forward in the wing.

I am curious as to the construction of the aircraft and the manner that is assembled prior to flying. As evidenced in other videos of this aircraft, these maneuvers were something they usually done before. I can't imagine it had flown enough to be experiencing fatigue in the structure and either wasn't properly secured prior to flying or had been damaged...

Just kind of thinking out loud here.
Old 09-19-2016, 04:41 PM
  #43  
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Bottom of the page shows the rudder.

http://www.rc-network.de/forum/showt...sse-2016/page8

Regards,
Old 09-19-2016, 05:46 PM
  #44  
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What I find amazing is just how violent thin air can be. The aero loads placed on the structure after the fin folded, literally shredded it to confetti.

I wonder how fast it was travelling. From the video it looked to some speed on, but it must be hard to judge, being such a big model.
Old 09-19-2016, 05:58 PM
  #45  
radfordc
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[QUOTE=olnico;12258473]I don't think it is rudder flutter.
The pilot comes in at full power for a knife edge pass. Kicks the rudder in full travel.
The fin separates due to excessive aerodynamic loads. /QUOTE]

Same thing happened to the full size BD-10: https://en.wikipedia.org/wiki/Bede_BD-10

Fox's first prototype, N9WZ, was completed in 1994 and entered testing. Although it had been modified to incorporate the stronger tail of Bede's design, it broke up mid-air on 30 December 1994 when the vertical stabilizers failed due to a crossflow condition, killing Van Wagenen. The National Transportation Safety Board (NTSB) later concluded that Bede's fix was severely under-designed, and offered nowhere near the strength that had been calculated.[SUP][7][/SUP] Fox had not performed any testing to verify the redesign of the vertical stabilizer spars before continuing flight testing, instead relying upon the data provided by Bede.
Old 09-20-2016, 05:01 AM
  #46  
i3dm
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Originally Posted by Halcyon66 View Post
1/2 scale jet made of wood with a huge 40+ kg turbine. Hhhmmmmmm?
actually it had a 100Kg AMT Nike engine.
very sad incident.

on a brighter note, jetpower 2016 was awesome!
Old 09-20-2016, 05:15 AM
  #47  
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Any chance you could post on Jetpower thread some impressions of things that you found new and interesting? So far no one has posted anything. Flying is for me less interesting than the new planes / engines.

John
Old 09-20-2016, 05:18 AM
  #48  
i3dm
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Originally Posted by Jgwright View Post
Any chance you could post on Jetpower thread some impressions of things that you found new and interesting? So far no one has posted anything. Flying is for me less interesting than the new planes / engines.

John
Sure, can you link me to that?
Old 09-20-2016, 05:43 AM
  #49  
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Originally Posted by cmp3cantrj View Post
Which is why the preface to the BMFA GTBA/JMA gas turbine safety rules emphasizes the following point:


Pay attention to where and when aircraft are flown to
ensure the safety of people, property and the environment.


However if you read the CAP and the BMFA handbook you will find that the 50 metres is measured to the crowd line or pit line - not to the pilots' box which may lie inside it.

CAP 658 says:
At least 50 m clear of persons, vessels, vehicles or structures. This can be reduced to 30 m for take-off or landing. Other model operators and any assistants or officials may be within this distance; as may vessels, vehicles or structures under their control
Yes I am well aware of the allowance for pilots etc to be within the 50 meter rule. The question is, just how much inside is sensible ? Having seen, this summer, one pilot taking off between the runway centreline and the pilot box, then at about 10 feet, right I front of the pilot box, rolling to knife edge shows there can some seriously poor judgement. That was not the only case of close in flying, far from it. And just to be clear I am not concerned about the odd transgression, we can all do that, I am concerned at the repeated and deliberate close in flying by a minority.

I see absolutely no reason why some very simple rules, which accord with CAA guidelines cannot be considered the normal standard of operation at ALL jet event, each time, every time: Take off and land on or beyond the runway centreline with all other flying at or beyond the far edge of the runway. Dead easy to judge, dead easy to do, dead easy to manage and gives us all, pilots, spotters and spectators a reasonable degree of safety with little or no compromise to our enjoyment.

These were the rules at my last UK club, Rolls Royce MAC, and when I gave that safety briefing at one RR jet meeting at Hucknall , (sadly no more) I advised all that they would be enforced , we had no dissenters and an excellent meeting.

If if you read the AAIB Shoreham report and the subsequent changes to display distances initiated by the CAA in their bulletin., you will see that safety distances were considerably increased AFTER the event at Shoreham. What I am strongly advocating is that we all, always, conform to current CAA guidelines and good sense in the hope we can maintain our safety record.

I strongly believe, too, that, in the event of a radio fail safe, the engine should be shut down, not just go to idle after 2 seconds. I believe that is the norm in many countries, including the USA. Time we, in the. UK, caught up, and time , too, that, EVERY pilot gained a proper understanding of exactly how to set his fail safe. At a recent jet meeting one scrutiniser told me that almost 30% of pilots did not know how to correctly set the failsafe. That needs to change.

This Saab accident highlights just how quickly and unexpectedly things in aviation can go very wrong.

David.
Old 09-20-2016, 07:43 AM
  #50  
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