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https://aviation-safety.net/wikibase/wiki.php?id=214957
http://www.kathrynsreport.com/2018/0...-accident.html
I hadn't seen this posted, I just found out myself. Lost the left wing in flight. The aircraft was featured late in the week at Oshkosh this year. Terrible news.
This was heartbreaking news. I spent some time with Lance and wrote a feature about him and his airplane in the April issue of Sport Aviation. He was a lot of fun to talk with, and the work and dedication that went in to his airplane were an inspiration.
Condolences to his family and friends.
Hal, was this the small jet act that flew at Airventure?
Accidents are the all too often and all too real sad part of our kind of aviation. Try as we might , they just keep happening. We can promote the idea of safe flying ,but an objective and honest look would have to see that as a goal, not in reality. The accident report is so early that we dont know in depth, other than a wing came off at low altidude, We dont know if that was a case of a problem in design or construction or pilot overstressing with high g's. We do know that it was a one of a kind design outside the normal proven, more safe and maybe more boring types like a 172, and likely was being flown in higher performance use like acro with more stress and requiring higher level of piloting skill. You can do a lot of fun things, play football, ski race, etc and you are most likely going to be injured, maybe seriouly, but not fatally. Only something else like 200 mph motorcycle racing is really life risking.
I shot some video of it at Oshkosh.
https://www.youtube.com/watch?v=1TxydAnS2oE
The report is out
https://www.ntsb.gov/_layouts/ntsb.a...th=9&year=2018
Does anyone know if the wings were built per Long EZ plans or if they were modified in any way?
No, this was an airplane that was originally inspired by a Long EZ but got bigger and beefier as it was modified for turbine power.Quote:
Originally Posted by Bill Greenwood
He used a modified and updated E-Racer wing with blended winglets.Quote:
Originally Posted by Mike Switzer
Hmm.. I would think that would be plenty strong unless there was some sort of defect.Quote:
Originally Posted by Hal Bryan
Strong enough, almost certainly. But from the facts so far available, the issue appears to be more one of stiffness than of strength, in particular torsional stiffness that increases flutter resistance.Quote:
Originally Posted by Mike Switzer
The kinetic energy available to do aeroelastic mischief is proportional to the square of the velocity. Once you get up above about 200 knots, that curve is awful steep, and once flutter starts it can tear things apart astonishingly quickly.
[QUOTE=BoKu;72832 and once flutter starts it can tear things apart astonishingly quickly.[/QUOTE]
Bingo!
That "wave like movement" or flutter the witness reported might be bending. Happens more in long flexible glider wings, I think.
I agree, I would suspect a defect that led to failure.Quote:
Originally Posted by Mike Switzer
Yea, my thinking is that some of the ERacers with hopped up engines go way faster than he was at the time of failure.Quote:
Originally Posted by martymayes
If I remember correctly this aircraft had an incident a while back where a downwind landing was necessary. The brakes caught on fire, licking the under-slung tanks and wings. No significant damage was observed at the time. I wonder if the heat caused unseen delamination in the wing skin allowing it to flex.
This is so sad. I thought this aircraft was so cool this summer at Oshkosh. I hope they figure out exactly what went wrong. I didn’t know the pilot but his creativity, ingenuity and outright skill were on full display at Oshkosh flying this amazing aircraft. My thought and prayers go out to him and his family.
I would really like to see if they can find a definite cause of the failure, unfortunately due to the post crash fire & the construction methods used, that may not be possible.
I think it would be hard to say how fast he was going on that last pass. So far as I know, no video has yet surfaced, and it is way too early for the NTSB data recovery team to have gotten anything out of the avionics.Quote:
Originally Posted by Mike Switzer
--Bob K.
My gut feeling is this pass was considerably faster than what was claimed. I can not see how this plane would only be flown at speeds a near stock piston powered version can make a pass at.
NTSB has the outer wing fragments to look at. Being the failure happened there they can learn allot how delaminations and control surfaces failed. They might not be able to analyze the flutter characteristics or the bending loads induced to the wing from the winglets at this point but can look at how flutter or other loads tore the structure apart.
Myself, I do not like the four pods under the wing, the airflow between them at speed could well create problems. But it was not the inner wing section where the failure started so I do not expect the pods were a cause.
FWIW I have a Long EZ here in my yard. The airfoils selected and the lack of balancing of control surfaces may be fine when flown at 200 but I personally would not fly this at 300+ without allot of design changes.
I'm not going to speculate on the crash cause, but I want to correct an inaccuracy (and I'm pretty sure we've had this discussion before). Long-EZ's (and all Rutan derivative canards - Variezes, Long-EZs, COZYs, Berkuts E-Racers, etc.) have 100% or more mass balanced elevators and ailerons. If the one in your yard isn't balanced correctly, well, that's not a fault of the design. The only surface that isn't balanced is the rudder, and that's because it only moves outboard and has a hard-stop for inboard movement.Quote:
Originally Posted by CharlieN
Correctly built EZ's have been flown and tested to 240 KIAS - possibly higher - without issue. But as has been pointed out, this was NOT a plans built EZ of any type - it merely resembled one.
Stupid question, what material is the wing made from? How about the spar and inner structure? What area failed?
A LongEz from which the plane was derived is made from styrofoam, fiberglass cloth and epoxy resin. This plane was beefed up to be "stiffer" which suggest maybe some carbon fiber cloth was added. The spar web and spar caps are the same materials. Not clear yet where the failure originated.Quote:
Originally Posted by enginesrus
All materials I would not care to trust keeping me so high off the ground. Its bad enough thinking about some small bolts taking some huge stresses, I'm just not a composite fan, and for real Styrofoam? Maybe good material for cushioning items in a box for shipping, but there is no tensile or bending nor shear stress capabilities with that material that I know of. And fiberglass? I've seen way to many kenworth size truck hood fender combo's with major cracking in very low stress area's.
Wing separation is a no brainer on that one.
You realise... Nevermind.Quote:
Originally Posted by enginesrus
If you don't know what you're talking about, it's better not to say anything.Quote:
Originally Posted by enginesrus
The foam is just to help mold the skin to the right shape. It does not carry any structural load except to resist oil canning and local buckling, which are all small forces.
I don't think that's exactly true. I'm not an engineer, but I'm pretty sure that the foam is indeed loaded in shear as it reacts lift loads out of the skin and into the spar. An engineer like Marc Z. could tell us for sure, and probably exactly how much.Quote:
Originally Posted by David Lewis
--Bob K.
You have heard of SpaceShipOne?Quote:
Originally Posted by enginesrus
Many small boats ,from sailboat to powerboats to kayaks etc are made of fiberglass and they work well, I think they might be a little heavy in thick sizes for airplanes. As for strength, think of the pounding a ski boat takes in normal day of hitting waves and wakes and they dont redily crack. Think of the pounding a surfboard takes and it is often a foam core for shape with glass wraps around it for strength.
Eh, a little bit, but Mr. Lewis is pretty much correct at least in the case of the blue flotation foam used in the wings, canard and winglets of canard aircraft. Mostly, it's there for ease of fabrication (gives shape without a mold) as well as supporting the skin against sheet buckling.Quote:
Originally Posted by BoKu
Well, if we had an engineer like Marc Z. hiding somewhere around here, maybe he could tell us for sure (and how much), but thankfully, I know of none. Marc Z. himself, however, cannot tell us for sure (or how much) - only what his understanding of the situation is :-). Which is that the actual shear transferred by the foam is a very small percentage of the total, if even measurable.Quote:
Originally Posted by BoKu
However, the facts are clear that composite materials (foam, fiberglass, epoxy) are completely capable materials for the construction of both experimental and certificated aircraft, when designed and used appropriately.
This is the 21st century and composites are in. Boeing is having good luck with the 787. Airbus over in Alabama is doing just fine with the A 320. When the Sikorsky 76 hit the market, I got checked out in the type. (before there even was an "A" model.) The structure forward of the MLG is Kevlar honey comb. Its called the Kevlar Komet. I've seen some of these AC take some horrible hits, flown into the ground or rolled over. They were all put back in service. There are at least 3 nations that use these as combat aircraft. No problem with structures. Our civilian models got hydraulic and electrical upgrades however from lessons learned in the military ops. This type weighs in lighter than semi monococ aircraft, but a lot tougher. And they don't corrode.
I'm glad to see that several posters to this thread are looking at aileron flutter. If that turns out to be the cause, it doesn't matter how much you up grade the hardware or even make the wings of plate steel.
Bob