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Collapse on reflex


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Yes, this WAS 'pilot induced' as an experiment. By Tony Gibson from South Africa.

Full slow on the trims, (on an action GT) full speed bar, and loads of pulling on the A's.

SW :D

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I have had a few myself...

The most dynamic of which was on full speed bar, full fast. It was a full frontal collapse.

It popped out in less than a second, I lost 90ft in height.

SW :D

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I saw a guy flying no more than 100ft off the ground have a 50% collapse wich popped back out in a fraction of a second, the other half of his wing came straight in and did the same, it threw him around a bit but he must have lost no more than 20ft in height, when he landed we had to tell him what happened as it had happened so quick he did not have time to look up and see it.

Dave.

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  • 2 weeks later...

Flew Old Orchard Beach in Maine a month ago and the return trip was a cross wind fast trim run (on my Fusion) without wingtip steering lines. Crabbing with left brake on fast trim had the wingtip pulsing in and out in gradient. There was minimal forward speed without fast trim after the wind picked up and the choice was to land out or be vigilant of the impending collapse. Will not omit the stabilo line steering on a high hang point machine again, even if the wind on take off is favorable like this trip was.

Using brake on fast trim is a no no i know know, won't happen again because I installed an Epsilon 4 big ears kit for wingtip steering. Thanks to Todd who could be on the R&D team at any shop.

tipsteer on fast,

Marko D :wingover:

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Yes I am very fond of the ALC steering and also the TST setup, and the pilots who dare to experiment. Being a bit of a follower, I normally consider any mods should be made by the manufacturer when it comes to wings, we will see if the Prussic knot goes from the factory issue. Kudos to Dudek for implementing the ALC and more Kudos to Mr Carnet for breaking the ice.

The knot scares me that's all, same for brake handles through a non-netted cage...the smallish risk need NOT be there.

Scaredicat,

Marko D

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Fanman

I am sure it has been mentioned before on the forum but not sure where!

Can you point me in the right direction, or advise, about the ALC system you are using on the Revolution.

I never got on with the tip steerers (always seemed to be in the way) and would be interested to find out more about any alternatives.

Cheers

Eddie

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The first thing to say about doing the ALC mod is that it is taking the wing away from its certification so it is something that you do at your own risk having understood all the implications for yourself.

ALC uses a single separate line to be able to operate the outermost part of the brakes leaving the central majority of the trailing edge fully reflexed. The upper attachment is to a suitable brake cascade (I plan to use the connection where ES3 joins ET9 and ET10 which is where the outermost tertiary brake lines go up from the outermost secondary brake line). Production Dudek wings use a higher outer cascade but I find their ALC less responsive than when I have attached one cascade lower down. Dudek take this new line down to a height adjustable red ball before the line then ties on to a length of black elastic. The elastic goes through a small metal ring at the base of the B riser, then up through another metal ring at the top of the B riser before coming back to the lower ring again where it is tied off. The reason for this elastic is that the trim can then be extended or shortened while the elastic maintains the correct line tension. As the attachment is on the B riser, if you didn't have the elastic then the effect of letting out trim would be to apply both outer brakes.

Edited by Guest
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There is a slightly simpler way of rigging the lower end of the ALC lines. Instead of rigging the line via elastic through rings to the B line it can be connected to the trim tab buckle area. It will sit a little higher but as long as it is at the buckle or above it will not be affected by trim position. This simplifies the set up on the risers too.

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The effect of the ALC is that it gives you a different feel to the turn. I always find that turn using tip steering is very draggy causing a ponderous high yaw turn. The ALC gives much more roll than yaw which is much quicker responding feeling more 'fighter' like. Although the principle of the ALC is for use on faster trim settings it works well at all areas of the trim range without disturbing the airfoil shape over the key part of the wing and creating such large amounts of drag as when using regular brakes. If flying low level on fast trim then you can have the brakes in your hands (but unused) while actually using the ALC steering so that if you have an 'oh sh1t' moment then the brakes can be dabbed to avoid sudden unexpected contact with the ground!

Dudek wings no longer have TST fitted as standard (no need as ALC is way better) but have revised the principle into TEA (torque effect adjuster). This is a form of TST that can be engaged or disengaged (and latched on) pre-flight or at any point during flight to offset prop torque.

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Thanks for the in depth explanation. Other wing manufacturers use a similar steering on reflex wings is this a reasonable statement? The Paramania is not compromisiing reflex with steering at the fastest speeds and someone said this ALC steering does not take the reflex away but this sounds questionable to my unexperienced ear...how do you get to keep the cake and eat it too.

Performance - Stability we want them both.

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Not exactly. Tip steering preserves the reflex profile by creating drag at the tips from pulling the stabilo line (outermost B running to the trailing edge of the tip). ALC is using brake to the outside trailing edge (where the wing is more turned down) so yes the reflex is pulled out of this part of the wing when applied but the main load bearing part of the wing is still fully reflexed and resistant to collapse. No other manufacturer is doing production wings with ALC as yet AFAIK.

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