if i loose a winglet ??

[matteo zangi]

hi folks

i need an opinion from you

can a cozy mk IV fly in safety (well! land safely as soon as possible ) if i loose a winglet during a flight ?

thanks matteo zangi

[Marc Zeitlin]

hi folks

i need an opinion from you

can a cozy mk IV fly in safety (well! land safely as soon as possible ) if i loose a winglet during a flight ?

thanks matteo zangi

It is extremely unlikely that it could. While no COZY has ever lost an aerodynamic surface in flight, a Vari-Eze or Long-EZE (don't remember which it was), lost a winglet in flight, due to an extreme builder error (he had apparently left the peel ply in the main structural layup that held the winglet onto the wing). After 40-50 hours of flight, the winglet departed and the plane crashed.

 

So, the evidence would apparently indicate that controlled flight in such an asymmetric configuration would be problematic at best.

[Spodman]

Canard Pusher article

 

"...we had yet to hear of an in-flight failure of a Rutan design - until June 21st when the caller described a winglet ripping off a VariEze at 200 + mph during an airport buzz job... The cause was tantamount to leaving the wing attach bolts off your Cessna and expecting the fairing strip to hold the wing on... The aircraft yawed, rolled, and pitched up 90 degrees. The calculated 13-g loads did not fail the wings but twisted the fuselage enough to shed most of the Plexiglas from the canopy frame. The aircraft impacted inverted on the prop and top cowling... with lay-up #8 omitted and with lay-up # 9 not extending to the lower skin, the only structure opposing the bending was the foam core..."

 

And so on, it probably didn't all fit on the builder's tombstone... I don't know if excessive speed contributed to the loss of control.

 

Just because there are two winglets, one is not a spare I guess.

[CBarber]

Wow, what an extreme example. It made me pause and REALLY try to think about my past layups and peel ply again. Howerver, since peeling off peel ply in the morning is kinda like a mini Christmas to me, I think it very unlikely I have forgotten any.....I hope <g>. Also, I tend to only use peel ply on the final lay-up.

 

Now, all that being said, until I actually built/attached winglets I was curious how they stayed on. Now that I know about composites (well, kinda know) I have no concern in that area. I am much more concerned about a bolt loosening or pulling out of its threads (such as on the canard) than a good composite bond failing. I would think, other than what is mentioned above, that the only way to loose a winglet is to have someone elses wing strike it. It is impressive how solid the winglet joint on my Velocity is.

 

Also, there is a modified Velocity (the Firefly) which has no winglets. It uses to verticle stabilizers off of booms just outboard of the fusalage, one on each side of the prop.

 

All the best,

 

Chris

[Wayne Hicks]

Going from memory, the Cozy IV winglets are designed to withstand being forced into the wind sideways at something ridiculous like 199 MPH (I believe it was MPH).

 

When Rutan did his destructive testing on the volunteered Vari-Eze, the winglet was loaded to well over 16 G's. (Again, going from memory.) While it's not exactly a Cozy winglet, it shares the same heritage.

 

On the peel ply, I was always perplexed as to how someone could be bone-headed enough to do a layup over peel-ply. That is until it happened to me -- TWICE! Once while forming the landing gear tabs and once on the glass-to-glass overlap on the leading edge of the wing.

 

So now I either use colored peel-ply, or mark the stuff with red X's to ensure I never do that again.

 

I agree with Chris' Christmas method of peeling it off ASAP.

 

....Wayne Hicks

[Spodman]

Just to show there is some good news in the Canard Pusher, here's an article where they tested a canard to destruction (with 400 witnessess!) with ...one bag short of a 14 g load on each side...

 

"...there was not one tension failure. The attach points (lift tabs) did not fail."

 

Information from 20 years ago like this gives me a lot of confidence in the Cozy, I like the comment in the other article that the Vari-eze was designed with poor workmanship in mind

[Jon Matcho]

From CP45, Page 3, July, 1985

This was 1725 lbs. on each side, for a total load of 3450 lbs hanging on those little lift tabs!!

That is rather impressive, but I wonder what can be supported in the oposite direction (downward force). The reason I ask is so that I just might have a place to sit when my plane is parked.

 

I didn't see anyone sitting on their canard wings at SnF.

[Dan Tomlinson]

Sure did! But I won't tell on Marc!

 

To be fair, he was inboard!

 

/dan

[birdman]

if i'm not mistaken, voyager lost a winglet on take off due to wing droop from fuel load resulting in the bottom of the structure being ground off. the winglet dangled for some time and they shook it loose- however voyager has two verticle stabilizers and the winglets do not appear to be as critical as in the e-z family. just build it right and don't forget to peel the peel ply!(i like the idea of marking it in color- we don't want to be building our coffins!)

[Jon Matcho]

I caught the last few minutes of a story about an F-15 losing an entire right wing in flight, but making it back to base. The pilot couldn't figure out why he couldn't get his airspeed down for landing. He didn't know that he lost a wing until he landed, when he said, "If I saw that I'd have ejected."

 

Here's the story: http://www.uss-bennington.org/phz-nowing-f15.html

 

And here is another similar story: http://www.richard-seaman.com/Movies/Aircraft/MilitaryAccidents/F18TopGunMidAir/

[Spodman]

Voyager lost both winglets from takeoff damage. They dragged because of three last-minute changes to the u/c trim & fuel load.

 

After takeoff the right winglet was waggling on its wires and a bit of glass, then folded back almost on the top wing surface, so they purposely broke it off in a sideslip. The other fell off in turbulence a bit later.

 

It was just luck they didn't lose a fuel tank or two, there was a few feet of wing added for balance after the fuel system was finished.

 

Despite the shiny new-age look of the Voyager, its flight was just as significant, just as on the edge of possibility, and just as on the edge of hairy disaster as anything from Alcock & Brown, Lindberg or Kingsford-Smith.

[Wayne Hicks]

The Voyager's winglets were very very small compared to the length of the wings, and as such, functioned more as endplates rather than as how Whitcomb had intended them. That's why the loss of the first winglet did not significantly impact the already ill-handling nature of the Voyager.

 

Furthermore, the Voyager's winglets did not serve as the rudders. Voyager employed a more convential vertical stabilizer/rudder set-up on the aft ends of the booms.

 

Big difference when compared to losing a Cozy winglet.

 

...Wayne Hicks

[Dan Tomlinson]

There would be a huge difference between losing a lower winglet which I suspect would come off relatively easily, and the main upper winglet which would be "difficult" to remove - chainsaws etc come to mind!

 

Just completed mine, and the plans indicate 90 degree slip at 170 kts I believe (plans in hangar) for the upper winglet. Consider the 9 ply, 30 inch wide "tapes" that hold it on both top and bottom, inside and outside - 27 plies directly attaching each one?

 

Grinding through that much pure glass would definitely take a "lot" of dragging.

 

That's the upper winglet where the rudder is. It is a critical flight surface, and would be aerodynamically equivalent to losing about 3 feet off the end of the wing, but highly unlikely!

 

The lower winglet (below the wing) would grind off or possibly even break off relatively easily, and is only lightly attached. However, you'd still notice it as it would change the stall speed of that wing slightly, but the aircraft would remain completely controllable without it. Some aircraft have been built without it against the recommendations of the designer, and flown successfully. It's purpose appears to be largely as an air dam to keep the lifting air under the wing and limit vortices developing off the tips.

 

Why worry about something that's highly unlikely? Why spread ugly rumors about losing wings?

 

Just keep the pilot side up on landing!

[Spodman]

New information from the old CP44:

 

"A Florida Long-EZ was substantially damaged when it struck two power

lines while flying level at approximately 140 knots, between two

islands. The lower power line removed the main gear entirely,

including the attach fittings, some lower fuselage structure and some

of the prop. The upper power line cut the upper left winglet off just

above the standard rudder. This piece was recovered by fishermen and

measured 37" at the leading edge and 27" at the trailing edge. The

pilot reported that the impact felt like light turbulence!!

The aircraft was put into an immediate climb. The pilot managed to fly

at 600 feet using nearly full right aileron and full right rudder, for

a distance of 4 miles over saw grass and trees to a power plant. A

1,500 foot strip of rock and dirt was chosen (all that was available)

and a normal off field landing was executed. The pilot was not aware

that the main gear had been torn off, so he put down the nose gear and

speed brake. The Long-EZ was damaged in the crash landing, but both

people on board suffered only bruising from the seat belts and shoulder

harnesses. The aircraft was losing altitude and thrust even though the

engine was developing good power, due to prop damage. The pilot did a

really excellent job in keeping his cool and flying the airplane."

 

"...just above the standard rudder..." means 2/3 to 3/4 of the fin gone! Looks like control authority may be a problem is any more goes. You would probably need Dan's chainsaw to get the whole thing off. What an amazing crash