Hey John, I'm out of KCFO and have been looking for a EZ for my commute while I'm building my Velocity. Mind reaching out to talk about your bird?

Thanks,

Kris 

1 hour ago, Ron D said:

I heard the 2.5g restriction was due to a less than perfectly built spar cap failing ... Is that about right, that it's basically two different issued, but the load restriction came from the build quality problem?

My interpretation is the same as @Kent Ashton's - the "G" limit restriction was due to corrosion, but obviously any defects in main spars will be problematic as well.

1 hour ago, Ron D said:

Has anyone ever had success with NDTing the attach fittings?

I am not aware of anyone who's ever done X-Ray or Ultrasonic inspections of the wing attach fittings. I suppose it's theoretically possible to check for corrosion that way, but you'll learn almost nothing about the spar cap deficiencies.

14 minutes ago, Kent Ashton said:

However, a 21 year old Vari that was load-tested was said to reach 7G...

And I've destructively tested an old VE that had been sitting in Bakersfield (desert, for the most part) for many years, and it failed (wing attach fittings) in the 7.5G - 8G range. NOT due to corrosion but due to the attach screws tearing out of the spar caps. Since the plane was a 5G plane and the safety factor would have been somewhere in the 2X - 3X range, one would expect failures in the 10G - 15G range (and I've heard of at least one VE that failed around 14G), but 7G - 8G is completely unacceptable performance. There's a reason that no airplane uses the VE wing attach fitting scheme (other than the VE).

17 minutes ago, Kent Ashton said:

I have never owned a Varieze but I wouldn't fret much about build quality if the plane appears to be well-built...

While I've flown a VE, I've never pulled more than 1.5G, and this attitude makes me a bit queasy. The problem with wing attach fittings is that what they APPEAR to be is completely meaningless wrt structural integrity.

19 minutes ago, Kent Ashton said:

I cannot recall a Varieze inflight failure attributed to the attach-fittings.

There has been one in-flight failure of the upper attach plates due to corrosion. The wing failed upward by a few degrees, and when the pilot landed, the wingtip collapsed onto the ground. No injuries.

Given that I've personally seen 4 sets of corroded wing attach fittings that came out of flying VEs (and posted pics, IIRC) and that there are only a few hundred VEs still flying, I am extremely sensitive to the question of whether a VE with unknown build quality and provenance is an appealing purchase. That's a HUGE catastrophic failure rate.

If one is building one from scratch (and there may be a few of those in process, still) one has the ability to adjust for the known deficiencies in the design, but it's still a question mark to me.

I do not think the 2.5G suggestion was due to build quality but due to corrosion found on the wing attach fittings.  See this in CP53-7 but there are 110 mentions of "wing attach" in the Canard Pushers so read more about it.    http://www.cozybuilders.org/Canard_Pusher/1987-10_cp-53.pdf

However, a 21 year old Vari that was load-tested was said to reach 7G but the article does not say how the airplane was stored   http://www.cozybuilders.org/Canard_Pusher/RAF_LE-Structural-Test.pdf

Here is a video of a guy who took the fittings apart but doing it on a flying airplane does not look practical to me.  https://youtu.be/FEftp5OT1-A?si=IDJlm9UUswTFJ-eJ

I have never owned a Varieze but I wouldn't fret much about build quality if the plane appears to be well-built.  Most builders are careful and there is not much history of failures of any of the Rutan canards due to build quality.  The issue of the corroded fittings is more difficult.   I cannot recall a Varieze inflight failure attributed to the attach-fittings.  Maybe some have been grounded because the owner saw something there.  I don't know.  For me, if the airplane had been hangared during its life, I'd think I would take a chance on it and fly it conservatively. 

Thanks to Marc for preserving these links on the Cozybuilders website.  He will certainly have more practical experience with Varis than I have.

Am 12.3.2021 um 16:46 schrieb Marc Zeitlin:

[...]

Now, given the wing attach fitting corrosion issue, RAF lowered the limits to +2.5G and -1.5G, based on nothing other than "sh*t - we don't know what to do about this, but the wing attach fittings might be substantially weaker than planned". It was intended to be a temporary change while a fix was developed, but no fix was ever developed by RAF.

So, I have to ask: I heard the 2.5g restriction was due to a less than perfectly built spar cap failing and RAF worrying that other builders may also have built poor quality spars due to instructions lacking in clarity or whatever. The massive corrosion was then found when inspecting the failed spar. Is that about right, that it's basically two different issued, but the load restriction came from the build quality problem?

I'm asking because there are some VariEzes which spent their whole life in dry hangars far from the sea and I've also seen some with alodined attach fittings, so there should be less chance for corrosion, but who knows about how the spar is built? And on the other hand, some builds were supervised by certified mechanics and had to endure limit load tests, so the build quality is probably okay but the corrosion issue still looms...ugh.

Has anyone ever had success with NDTing the attach fittings?

vor 11 Stunden schrieb jridge:

I think you mean flaps?  The Cozy does have ailerons.

Not easy to integrate flaps into a canard design. Starship had a variable sweep canard to deal with the shift in trim when flaps were deployed. Maybe one could build a flapevator canard with some complicated linkages to keep trim in check, but I'm not sure if it would even be possible to ensure the canard stalls first in all configurations.