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Jet nose cone caves in mid-flight

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Jet nose cone caves in mid-flight

Old 8th Jul 2008, 14:26
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Granted I am not a pilot and generally visit this forums to learn about
real aviation from alleged professionals. Normally I don't comment on
matter outside my experience. However being a professional structural
engineer I know that whatever struck the cone of this aircraft was no
bird or lightning strike. Any structural engineer or anyone with experience
in impact assessment looking at the cone of this aircraft would readily
identify 3 specific points of impact which could only be made by a solid
rigid object. I supposse your total ignorance in these matters reflects
your useless reply.
people that live in glass houses shouldn't throw stones.

One has to consider the layup of the cloth used to make the cone shape as well as the structure immediately behind it (radar equipment).

While considering the possibilities of an inflight collision (birds, etc.) there are also air loads on the dome both of which have an effect of buckling the dome inward. Buckling deformations/fractures on such a dome shape result in a great deal of varriations so I wouldn't be too quick to assess 3 discrete points of impact.
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Old 8th Jul 2008, 15:05
  #22 (permalink)  

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could be worse - could have been 20mm sparrows...

(sorry, was watching "Thirteen Days" last night - I'll get me coat)
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Old 8th Jul 2008, 16:34
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Three point of impact on a straight diagonal line....Ok - I've given you my opinion, Let's wait for the official explanation for this "rare" occurrence, assuming they'll ever give us one.
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Old 8th Jul 2008, 17:52
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Since these nose cones usually are made of fiberglass or
similar, maybe it got hit by a vehicle on the ground before flight
weakening the structure - just a wild guess..

M
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Old 9th Jul 2008, 01:46
  #25 (permalink)  
 
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A P-3 from NAWC-23 at Dallas Love Field had a crushed nosed cone and did an emergency divert into Davis-Monthan AFB a couple of years ago, lightning was mentioned in more than one account but these guys don't give out much information when they fly:

Photos: Lockheed P-3C Orion Aircraft Pictures | Airliners.net
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Old 9th Jul 2008, 01:55
  #26 (permalink)  
 
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I seem to recall some years ago at LHR, a truck drove into the radome of a BA 757 and then drove off.

The crew did not notice the damage and took off and only realised something was amiss when they could not pressurise the a/c and were getting cold feet !

The impact had damaged the pressure bulkhead as well as the radome.

The vehicle driver was subsequently fired.....

No organic remains visible on this particular radome. Ground damage me thinks or possibly pre existing delamination which then failed on the incident flight.
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Old 9th Jul 2008, 02:44
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Whilst I was flying P3B/Cs in the RAAF, we had two instances of nose radome damage, one where three pelicans (in formation) collided with the nose of the airplane, two into the radome, smashing it to pieces (worse than the P3C pic earlier), one of which penetrated the fwd pressure bulkhead and punched out several engine insts and splattered the pilot, similar to that RJ pic. The remaining bird hit the CPs windshield, very lucky, since thats the strongest part of the airplane, and just bounced off.

The other instance was during a very violent hailstorm inflight, miles downwind of the cloud source (I learned something there!), which resulted in the nose radome folding inward, very similar to the B757 pic shown.

Cheers...FD...
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Old 10th Jul 2008, 23:59
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Maybe it hit a UFO???
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Old 11th Jul 2008, 01:56
  #29 (permalink)  
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UFO? This person thinks so . . .

"Most likely not another word will be heard about this incident. Government officials wouldn’t want to “alarm the public” by making them aware that unauthorized spacecraft could easily collide with any plane they fly on, and possibly completely destroy it."

Data4Science.net
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Old 11th Jul 2008, 03:43
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Algy,
It was real - I've seen it in BA service e-mails but it's on a CL604 (the displays on an RJ are portrait not near-square like the Challengers') and the CF34s are too close to the camera for a CRJ too. Just wish we had FSRs like the one in the picture!
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Old 11th Jul 2008, 05:03
  #31 (permalink)  
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Not at all unusual. Sometimes you see an aircraft with a different coloured radome that has been borrowed as a pool spare from a pool partner airline. I can recall two instances of shattered or stoved in radomes due to lightning strikes or hail damage during my flying days.
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Old 11th Jul 2008, 07:14
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Eboy said....

"UFO? This person thinks so . . .

"Most likely not another word will be heard about this incident. Government officials wouldn’t want to “alarm the public” by making them aware that unauthorized spacecraft could easily collide with any plane they fly on, and possibly completely destroy it."

Data4Science.net

Aviate adds.....

Ted Twietmeyer - Google that name!
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Old 11th Jul 2008, 08:14
  #33 (permalink)  

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Skywreck,
Are you suggesting some sort of conspiracy? Radomes fail occasionally, usually for the more rational reasons stated earlier on this thread. I've seen some rejected for excessive moisture content and lightning damage; it happens.
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Old 11th Jul 2008, 08:42
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collapsed radome

Like 40 years back on a Britannia out of Istambul to Bombay we entered cloud and picked up a load of static; blue lights on windscreen and props, increasing noise on the vhf, till BANG a lightning discharge off the nose. Radar stopped working as the dome partly collapsed. The really interesting thing was the rest of the trip our True airspeed increased by 5 knots.
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Old 11th Jul 2008, 10:31
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Radomes

I blame it on Companies buying cheap Taiwanese radomes.

Let's face it, Wilyflier, any alteration to a Britannia airframe
would have been an improvement to it's aerodynamics!!!

Bring back the DC 8.

Last edited by Storminnorm; 11th Jul 2008 at 10:44.
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Old 11th Jul 2008, 11:31
  #36 (permalink)  
 
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3 specific points of impact which could only be made by a solid
rigid object
Wing bone/beak/wing bone

My birdstrike post was only a suggestion for pete's sake
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Old 11th Jul 2008, 11:44
  #37 (permalink)  
 
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Algy??
That's a simpic!!
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Old 11th Jul 2008, 12:01
  #38 (permalink)  
 
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wilyflier:
The really interesting thing was the rest of the trip our True airspeed increased by 5 knots.
Slippery when electrically (dis)charged! UFO stuff, no doubt about it...

GD&L
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Old 11th Jul 2008, 13:04
  #39 (permalink)  
 
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Bus429

It is my considered opinion that the dome was hit by some rigid object
at three points, the central point created the deepest impact which
imploded the dome and the subsequent stress/tension cracked the
fuselage. The rigid object would in my opinion not be straight or
circular but rather triangular or of irregular shape.

As for bird strikes and the like, that would have caused a greater deal of
damage and left a great deal of evidence, as shown in some of the pictures
posted in this Forum of similar incidents. Considering how thin the fuselage
is I would say that in this case the impact wasn't head on and at high speed but rather a sideways strike which just grazed the surface.
A full impact would have removed the frontal cone in its entirety and left a gaping hole.

As for UFOs and the like, I couldn't say. Perhaps the event ocurred at some
point before take-off or after landing, and it's possible someone doesn't want to take responsibility, who knows. My initial post was meant to comment on the fact that it couldn't have been a bird/lightning/hailstone
strike as those tend to leave a different type of signature/damage.
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Old 11th Jul 2008, 13:37
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Was once called out to assay a mysterious "thump" that occurred 400' agl at each take-off on a Fokker 100.

Thought it might be oil canning of structure either due to dynamic pressure loads or aircraft internal pressurisation loads. Got the pilot to fly slow climb one sector, fast the next to see which.

Turns out it was related to dynamic pressure - went and looked at the nose radome (which several people had looked at before) and it was pristine, looked like it had just left the showroom.

Don't know what did the original damage, but it was wrecked on the inside - damage had likely been made worse by repeated indentation during flight (which caused the "thump" and went away on the ground) and moisture ingress (repeated freezing & thawing expanding an area(s) of delamination, causing more water ingress etc).

Fact is, any or all causes could have happened to the radome under discussion at various times - lightning, birdstrike, delamination, moisture ingress, ramp rash, inappropriate repair etc. - and it could have appeared to passed muster while being badly compromised. And any one of those events could have precipitated the final failure too, quite possible a long time later, where on a good radome perhaps they wouldn't.

An issue of concern to engineers like me is that lots of composites behave this way - they can look good from the outside (the direction from which they have been hit) while being trashed on the inside. If you've seen the number of dents on and around cargo doors you'll be wondering how we'll cope with carbon-plastic fuselages on the A350 & 787. I don't know the answer.
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