Composite Helicopters KC518 Adventourer
"The reason we were over the water is because we are still in our flight evaluation phase, if you like." ??? Does not compute !
Extremely expensive prototype under development and yet it's okay to risk losing it in the salty sea. The engine didn't fail completely and it could almost certainly have been put down somewhere upright and on dry land with absolutely no ensuing damage, had it been close to the shore.
The carbon fibre airframe won't be affected by salt water immersion, but most of the alloy components will probably need replacing. Even short sea water exposure can initiate surface micro-pitting to bare metal.
Were lifejackets being worn by the occupants? What was the assigned crew function of the young woman on a development test flight? Would insurance have covered her in the event of a tragedy?
All credit to the pilot for executing a successful restricted power landing, but I suspect that the investors are going to want answers to the above questions. Watch this space.
Extremely expensive prototype under development and yet it's okay to risk losing it in the salty sea. The engine didn't fail completely and it could almost certainly have been put down somewhere upright and on dry land with absolutely no ensuing damage, had it been close to the shore.
The carbon fibre airframe won't be affected by salt water immersion, but most of the alloy components will probably need replacing. Even short sea water exposure can initiate surface micro-pitting to bare metal.
Were lifejackets being worn by the occupants? What was the assigned crew function of the young woman on a development test flight? Would insurance have covered her in the event of a tragedy?
All credit to the pilot for executing a successful restricted power landing, but I suspect that the investors are going to want answers to the above questions. Watch this space.
Last edited by Colibri49; 10th May 2013 at 23:32.
SALFEFC
Great job by the Pilot, well done 
welcome to the Club 
Successful Autorotative landing following engine failure (swimming away) Club 
Land Happy Always
welcome to the Club Successful Autorotative landing following engine failure (swimming away) Club Land Happy Always
Last edited by Vertical Freedom; 11th May 2013 at 23:51.
"The reason we were over the water is because we are still in our flight evaluation phase, if you like." ??? Does not compute !
The carbon fibre airframe won't be affected by salt water immersion,
What an age in which we live when a day after an incident the manufacturer releases onboard images complete with a description of the event.
Good stuff, better to get your own message out which then becomes the content of social media, rather than have ill informed opinion run amuck.
Mickjoebill
Good stuff, better to get your own message out which then becomes the content of social media, rather than have ill informed opinion run amuck.
Mickjoebill
"It does if you cannot fly over a built up area by being in experimental category."
This had occurred to me, but why fly over either a built-up area or the sea while performing development test flights? From Google Earth there would seem to be no shortage of open land between the concentrations of buildings.
The answer to the question about lifejackets should clarify whether the test flying programme was intentionally being performed over water because of unavoidable built-up areas.
Again, it would be interesting to know whether the young woman was an assigned crew member and whether she was covered by insurance.
NDT carbon structures would apply after heavy impact with land or water and doesn't address the question of whether the aircraft ought to have been so far out from the shore.
This had occurred to me, but why fly over either a built-up area or the sea while performing development test flights? From Google Earth there would seem to be no shortage of open land between the concentrations of buildings.
The answer to the question about lifejackets should clarify whether the test flying programme was intentionally being performed over water because of unavoidable built-up areas.
Again, it would be interesting to know whether the young woman was an assigned crew member and whether she was covered by insurance.
NDT carbon structures would apply after heavy impact with land or water and doesn't address the question of whether the aircraft ought to have been so far out from the shore.
Colibri, due to NZ accident compensation legislation, the insurance question isn't really applicable.
It seems to me unlikely they would want to fly that fuselage again though. Given the millions they have put into this project, I expect a couple of hundred k in the fuselage is not worth risking flight. It would make a good gate guardian now.
It seems to me unlikely they would want to fly that fuselage again though. Given the millions they have put into this project, I expect a couple of hundred k in the fuselage is not worth risking flight. It would make a good gate guardian now.
Quote from tartare: "For a tiny nation, NZ punches well above it's mechanical engineering weight."
Let me make it clear that I totally agree with this statement. That replica of a Mosquito WWII bomber is awesome. Furthermore the world's best electric VP propeller for light aircraft comes from Airmaster in NZ and that isn't only my opinion.
I have family in the Auckland area and it seems to me that NZ has the greatest per capita enthusiasm on the planet for aviation in all its forms.
So what's my gripe? Carbon fibre and lightning. For my recreation I fly an aircraft built of glass fibre composite and I'm very aware of how totally a lightning strike could shatter/pulverise the airframe.
I believe that the same applies to carbon fibre composite structures, which is why components of airliners built by Airbus and Boeing have metal mesh or perhaps other metalised layers embedded in the carbon fibre to dissipate static electricity and lightning strikes.
Furthermore there is the phenomenon of "helicopter triggered lightning" which is being promulgated by the UK Met Office and updated frequently throughout each day for North Sea helicopter operators to plan with. It takes account of a temperature band around the zero degree isotherm and other factors. No flight is allowed in red areas and amber areas are treated with caution.
From what little I understand of this fairly new science, helicopters with composite blades are far more likely to trigger a lightning strike than are aeroplanes. Perhaps due to air friction over the spinning blades which might excite more static electricity than airframe components.
Even if the KC518 doesn't have composite blades, I hope that they're doing something to dissipate static electricity in the fuselage. Failing that, they should be making clear on a prominent page in the flight manual the importance of avoiding potential lightning conditions.
Let me make it clear that I totally agree with this statement. That replica of a Mosquito WWII bomber is awesome. Furthermore the world's best electric VP propeller for light aircraft comes from Airmaster in NZ and that isn't only my opinion.
I have family in the Auckland area and it seems to me that NZ has the greatest per capita enthusiasm on the planet for aviation in all its forms.
So what's my gripe? Carbon fibre and lightning. For my recreation I fly an aircraft built of glass fibre composite and I'm very aware of how totally a lightning strike could shatter/pulverise the airframe.
I believe that the same applies to carbon fibre composite structures, which is why components of airliners built by Airbus and Boeing have metal mesh or perhaps other metalised layers embedded in the carbon fibre to dissipate static electricity and lightning strikes.
Furthermore there is the phenomenon of "helicopter triggered lightning" which is being promulgated by the UK Met Office and updated frequently throughout each day for North Sea helicopter operators to plan with. It takes account of a temperature band around the zero degree isotherm and other factors. No flight is allowed in red areas and amber areas are treated with caution.
From what little I understand of this fairly new science, helicopters with composite blades are far more likely to trigger a lightning strike than are aeroplanes. Perhaps due to air friction over the spinning blades which might excite more static electricity than airframe components.
Even if the KC518 doesn't have composite blades, I hope that they're doing something to dissipate static electricity in the fuselage. Failing that, they should be making clear on a prominent page in the flight manual the importance of avoiding potential lightning conditions.
Last edited by Colibri49; 11th May 2013 at 11:42.
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Composites and lightning
C49
I think that the composite lightning strike issue is overplayed and results from incorrect definition of testing requirements. If you test a composite panel in isolation with simulated lightning strikes, then yes there is damage and yes if you add a mesh the problem is mitigated. However many years ago I saw some test results from a French manufacturer of military jets where they tried testing composite panels but had them mounted in a metallic frame, in a similar manner to how a composite panel is bolted to an airframe, and they could not get the lightning to hit the composite area. It would always hit the metallic support frame. They also tried using a metallic strip around the panel which was grounded to the sub-frame using fasteners and had the same effect.
I have never liked the mesh approach because it is damned near impossible to implement a repair to the structure and then restore the mesh conductivity.
Regards
Blakmax
I think that the composite lightning strike issue is overplayed and results from incorrect definition of testing requirements. If you test a composite panel in isolation with simulated lightning strikes, then yes there is damage and yes if you add a mesh the problem is mitigated. However many years ago I saw some test results from a French manufacturer of military jets where they tried testing composite panels but had them mounted in a metallic frame, in a similar manner to how a composite panel is bolted to an airframe, and they could not get the lightning to hit the composite area. It would always hit the metallic support frame. They also tried using a metallic strip around the panel which was grounded to the sub-frame using fasteners and had the same effect.
I have never liked the mesh approach because it is damned near impossible to implement a repair to the structure and then restore the mesh conductivity.
Regards
Blakmax
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Has anyone begun doing experiements with bamboo? I feel dumb for asking this question, because it seems almost laughable, but I have read reports about the superior strength that it has over steel and I can't help but be reminded of the wooden blades of the Bell 47. Just curious.
C49,
NZ is still a free country. The owner was flying his own helicopter and within the bounds of the regulations he can do whatever he wants with it.
Placarded as follows:
WARNING – EXPERIMENTAL
THIS AIRCRAFT DOES NOT MEET THE
NEW ZEALAND AIRWORTHINESS
REQUIREMENTS FOR STANDARD OR
RESTRICTED CATEGORY AIRCRAFT.
PASSENGERS FLY IN THIS AIRCRAFT
AT THEIR OWN RISK
In accordance with AC21-3 - Civil Aviation Authority of New Zealand
NZ is still a free country. The owner was flying his own helicopter and within the bounds of the regulations he can do whatever he wants with it.
Placarded as follows:
WARNING – EXPERIMENTAL
THIS AIRCRAFT DOES NOT MEET THE
NEW ZEALAND AIRWORTHINESS
REQUIREMENTS FOR STANDARD OR
RESTRICTED CATEGORY AIRCRAFT.
PASSENGERS FLY IN THIS AIRCRAFT
AT THEIR OWN RISK
In accordance with AC21-3 - Civil Aviation Authority of New Zealand
Blakmax,
If you have the chance take a look at an EC135 tail.
Numerous issues with copper mesh over carbon interfaced with alloy components - nightmare! In some places bare alloy onto bare copper! WTF?
Carbon fibre boats are also fun if you forget that carbon is a very good conductor on its own.
I have never liked the mesh approach because it is damned near impossible to implement a repair to the structure and then restore the mesh conductivity.
Numerous issues with copper mesh over carbon interfaced with alloy components - nightmare! In some places bare alloy onto bare copper! WTF?
Carbon fibre boats are also fun if you forget that carbon is a very good conductor on its own.
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just thinking out aloud regarding composite structures and lightning strikes, couldn't a metal film mesh decal or simply lines of conductive metallic paint be applied to the outside of the composite structure and then painted over with normal livery to achieve the desired protective function?
The church I used to walk through to take a shortcut to work used to only have a very thin earthing wire that ran to the top of the steeple to take the load when lightning striked.
The church I used to walk through to take a shortcut to work used to only have a very thin earthing wire that ran to the top of the steeple to take the load when lightning striked.
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Thanks RVDT, so it's fair to say that there is already a proven and simple solution for protecting composite structures from lightning strikes. Perhaps it's application is not widely known by manufacturers of lightweight composite aircraft as I cannot imagine this to be a prohibitively expensive item to implement.
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RVDT
I haven't seen an EC135 tail but by your description maybe I should.
Catlletruck (love the tag!) If you calculate the weight of the decal and adhesive, maybe that approach is about the same as embedding a copper mesh in the composite resin. I still think the issue is being determined by limitations in defining the test parameters.
Let me give you an analogy. There was a fellow traveling on a bus in an Astralian city and he was tearing a newspaper into tiny pieces and throwing them out of the bus. The conductor said, "I noticed you throwing paper out the window. Stop that, it is littering!" To which the fellow replied "But that is to scare away the elephants". The conductor says "But there are no elephants at all in Australia". The reply? "Effective isn't it?"
If you set out to measure the results of an ill-defined test, you get the outcome you want.
If you want to discuss the stupid justification for removing cladding from aluminium alloy surfaces before bonding, I would be happy to oblige. Yet anther example of ill-defined test parameters, and this causes heaps of needless work for repair technicians and increases the risk of corrosion dramatically.
As far as inspecting the structure after immersion for impact damage this can be easily achieved by ultrasonic inspection by A, B or C scan methods. The warning I would offer my NZ friends is that if damage is detected, please do NOT under any circumstances use injection "repairs". You may in fact REDUCE the residual strength of the laminate.
Regards
Blakmax
I haven't seen an EC135 tail but by your description maybe I should.
Catlletruck (love the tag!) If you calculate the weight of the decal and adhesive, maybe that approach is about the same as embedding a copper mesh in the composite resin. I still think the issue is being determined by limitations in defining the test parameters.
Let me give you an analogy. There was a fellow traveling on a bus in an Astralian city and he was tearing a newspaper into tiny pieces and throwing them out of the bus. The conductor said, "I noticed you throwing paper out the window. Stop that, it is littering!" To which the fellow replied "But that is to scare away the elephants". The conductor says "But there are no elephants at all in Australia". The reply? "Effective isn't it?"
If you set out to measure the results of an ill-defined test, you get the outcome you want.
If you want to discuss the stupid justification for removing cladding from aluminium alloy surfaces before bonding, I would be happy to oblige. Yet anther example of ill-defined test parameters, and this causes heaps of needless work for repair technicians and increases the risk of corrosion dramatically.
As far as inspecting the structure after immersion for impact damage this can be easily achieved by ultrasonic inspection by A, B or C scan methods. The warning I would offer my NZ friends is that if damage is detected, please do NOT under any circumstances use injection "repairs". You may in fact REDUCE the residual strength of the laminate.
Regards
Blakmax
Last edited by blakmax; 12th May 2013 at 10:12.
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The church I used to walk through to take a shortcut to work used to only have a very thin earthing wire that ran to the top of the steeple to take the load when lightning striked.
They thus "milk" the charge from the ground and disperse it in orderly fashion towards the hand of God without waiting for the fist of Thor to smite them a mighty blow.
Often you will see a strong blue stream of what looks like light heading skywards from the sharp high point on the building at the end of the copper wire as a storm approaches.
tet.
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blackmax
I think you proved the point you were trying to make, but I'd disagree with the result. That airframe manufacturer should have been testing the panels as they would be installed. I'd be very surprised if in any real-life application the metal frame would be exposed like in the test.
The little first-hand exposure I have had to this is from friends who were flying the Emb145. They had a lightning strike in a composite wingtip in cruise and the result could best be described as a broomstick of fibers. The composite did take the hit.
The repairability of the conductivity isn't something I had thought about enough. Thanks.
C49
I think that the composite lightning strike issue is overplayed and results from incorrect definition of testing requirements. If you test a composite panel in isolation with simulated lightning strikes, then yes there is damage and yes if you add a mesh the problem is mitigated. However many years ago I saw some test results from a French manufacturer of military jets where they tried testing composite panels but had them mounted in a metallic frame, in a similar manner to how a composite panel is bolted to an airframe, and they could not get the lightning to hit the composite area. It would always hit the metallic support frame. They also tried using a metallic strip around the panel which was grounded to the sub-frame using fasteners and had the same effect.
I have never liked the mesh approach because it is damned near impossible to implement a repair to the structure and then restore the mesh conductivity.
Regards
Blakmax
I think that the composite lightning strike issue is overplayed and results from incorrect definition of testing requirements. If you test a composite panel in isolation with simulated lightning strikes, then yes there is damage and yes if you add a mesh the problem is mitigated. However many years ago I saw some test results from a French manufacturer of military jets where they tried testing composite panels but had them mounted in a metallic frame, in a similar manner to how a composite panel is bolted to an airframe, and they could not get the lightning to hit the composite area. It would always hit the metallic support frame. They also tried using a metallic strip around the panel which was grounded to the sub-frame using fasteners and had the same effect.
I have never liked the mesh approach because it is damned near impossible to implement a repair to the structure and then restore the mesh conductivity.
Regards
Blakmax
The little first-hand exposure I have had to this is from friends who were flying the Emb145. They had a lightning strike in a composite wingtip in cruise and the result could best be described as a broomstick of fibers. The composite did take the hit.
The repairability of the conductivity isn't something I had thought about enough. Thanks.
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Composites and lightning strikes
P'n'A
You do make a valid point, but that is a design issue. As long as manufacturers make composite panels which fasten onto flat airframe members, the substructure will not be exposed to lightning contact. However, the fasteners certainly will and it is my experience that even on metal structures lightning access points often are fasteners attached to sub-structure, unless there is a very large area of non-connected structure.
With chem-milling techniques it would be easy to leave a small ridge of metal at the joint of fuselage panels such that lightning would preferentially attach there.
In the "toothbrush" failure mode you describein the wing-tip example there is probably no metal at all, and for such structures maybe the addition of a lightning tracking path metallic option (even the decal suggestion mentioned before) would be a better option than just letting nature take its course with the consequent toothbrush result. Even something like a metallic leading edge abrasion strip would do that task. Heaven forbid, maybe the mesh option would be appropriate but someone please explain how you would repair the region? At least with a conductive decal, you could rip it off and replace it. You may need to do a local repair for the strike zone but at least the restoration of lightning protection would be definitively better.
Regards
Blakmax.
You do make a valid point, but that is a design issue. As long as manufacturers make composite panels which fasten onto flat airframe members, the substructure will not be exposed to lightning contact. However, the fasteners certainly will and it is my experience that even on metal structures lightning access points often are fasteners attached to sub-structure, unless there is a very large area of non-connected structure.
With chem-milling techniques it would be easy to leave a small ridge of metal at the joint of fuselage panels such that lightning would preferentially attach there.
In the "toothbrush" failure mode you describein the wing-tip example there is probably no metal at all, and for such structures maybe the addition of a lightning tracking path metallic option (even the decal suggestion mentioned before) would be a better option than just letting nature take its course with the consequent toothbrush result. Even something like a metallic leading edge abrasion strip would do that task. Heaven forbid, maybe the mesh option would be appropriate but someone please explain how you would repair the region? At least with a conductive decal, you could rip it off and replace it. You may need to do a local repair for the strike zone but at least the restoration of lightning protection would be definitively better.
Regards
Blakmax.
Last edited by blakmax; 13th May 2013 at 12:16.
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There are not a lot of new projects like this one in the heli world so after those bad times, I wish to offer my encouragements to the team !
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There are not a lot of new projects like this one in the heli world so after those bad times, I wish to offer my encouragements to the team !
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Last edited by HeliHenri; 13th May 2013 at 12:40.