This one was a surprise to us. Conditions were good, the pilot
competent, and his flying wasn't overly aggressive.
During the second
run of the 2012 U.S. Pylon qualifier, Michael Mixer was making
good time and looking smooth. He had been practicing and it
showed. I was recording and was impressed at how far his skills
had come and how relaxed he seemed to be on the course. It may not seem like
hanging on full speedbar is particularly challenging but doing so
smoothly, while making turns, coming on and off speedbar at the right
time, can be
more difficult than you think. He was smooth, fast, and making good race
First a few notes.
1) The Velocity Recon is a reflex wing where the tip
steering pulls approximately the outboard 20% of the trailing edge.
That's more than most reflex wings. There are also stabilo steering
toggles which are intended to be used on full speedbar but tare not
very effective, so competition pilots frequently push it by using tip
steering that activates the outboard brakes, in spite of increased risk. This
is essentially a prototype and, as such, remains up to the pilot to explore
2) The wing has little history of competition so
its behavior in this condition is not well understood. As of this
writing I have seen no pilot manual and doubt one was available at the
time this occurred. But even if there was one it doesn't mean this
subject would be covered. In a user manual for the Ozone Viper 18 it is
not mentioned because they only sell that wing to competition pilots who
know the risks and are on their own to explore its limits. That is, I
suspect, the situation with the Recon.
by Rick Hunts (below) shows that Mike is, in fact, using the tip toggles
which backs up what the pilot says (not using main brakes).
4) There was sand in the trailing edge, probably about 3 pounds per
side give or take a pound. You can see it in the video and witnesses
reported it while he was flying. Also, some witnesses reported some
"flapping" of the trailing edge although I could not tell anything more
than normal brake input and his hands are moving in small, frequent
amounts. It is, however, not uncommon to get some flapping when there is
sand in a wing and the witnesses were in a better position to tell.
On full speedbar, trimmed full fast, it came out of the blue. Just as
he started the second big turnaround, 25 feet high, a burble, possibly
from the pylon, pushed a little piece of the left wing down, breaking
through the minimal lift opposing it and started a cascade of actions
that, once begun, left no chance for recovery. As that little section
folded down the fast-moving slipstream pushed it down and back, pulling
more fabric with it until the entire left side was completely folded
down and back. It looked like the left side just "let loose".
Inertia did the rest, flinging him forward, up and left. He let off
the speedbar and power immediately, within a few tenths of a second, but
he was now along for the ride. I watched it step by step as did a number
of others (some will be on YouTube, mine will be in video 3, if not
sooner). You can clearly see the trailing edge deflected consistent with
main brake application prior to the deflation.
The wing reinflated when he was pointed straight down, about 25 feet
high, and swinging counter-clockwise. He impacted mostly face down but
on his right side then bounced and landed on his back. The bent-up cage
is testament to the paramotor having absorbed a lot of impact.
The most direct cause appears to be a combination of trailing edge
deflection and the rollout that was occurring which would have
redirected the airflow slightly downward, was enough to start a front
tuck of the left 1/3 of the wing. Being at full speed meant that, once
the tuck started, fast moving slipstream air pulled much more of the
wing down and led to the dramatic result. Contributing factors may have
been: 1) Tip Steering system that applies brakes over a relatively wide
range of trailing edge, 2) Sand in the wing, 3) Rotor from the pylon.
Regarding the wing's
tip steering affecting more of the trailing edge. I can
attest to this because, during my review, I noticed that I was able to
control pitch with the tip steering. That's quite handy, actually,
unless it destabilizes the outer part of the reflex airfoil. Testing
would be in order and, if I get a chance to fly the 22 again, I will do
the testing up high.
1. Don't fly the Velocity Recon
on full speedbar using any brake input including the tip steering. It
may work for some time but you are, in fact, far closer to a potentially
catastrophic collapse. Use only the stabilo toggles (see diagram
above right) when on full speedbar. There are quite possibly other reflex wings with
this same behavior but they have not been pushed as hard. Stabilo
steering has never, to my knowledge, caused this to happen so it should
be reasonably reliable. If you do test your wing (whether the Recon or
other glider) be prepared to do your test up high.
I flew this wing just like Mike did, using the tip steering,
when I reviewed it and was under the impression this would be OK.
Obviously it is not. Like the Hadron, when on fully speedbar and trimmed
fast, steering is only to be done through the Stabilo togles.
2. If you have sand in your trailing edge, avoid flying trimmed fast
and never use the speedbar. Look at the trailing edge, if it's
deflected, you have enough sand to worry about.
About sand in the
Here is an article with video from the German Certification
organization DHV about sand in the wing.
Here is the Accident Report. In the case of this accident,
approximately 3 pounds of sand in one stabilizer was found to make a tip
collapse and cravat more likely. Although this strongly suggests that
sand in the wing is more dangerous than most thought, these two
accidents are essentially unrelated. Michael's wing did not cravat and,
in fact, recovered almost right away. But the sand could have been a
factor because it would pull own on the very trailing edge just like the
brakes would do.
3. Realize that,
whatever wing you're flying, just because it hasn't collapsed on full
speedbar doesn't mean it's not about to. Michael had practiced a fair
amount and had never had anything like this. He was, essentially, doing
everything right and still this happened.
4. Consider reducing the
amount of inboard tip steering line connections.
Michael hit in the sand going probably 25 mph. Had he hit one of the
many solid objects nearby it would have likely been fatal. Had he not
been in such great shape it might not have gone so well, either. We are
lucky to still have him. Hopefully he will come back to continue his
contribution to the sport, it would be sorely missed. Whether he
competes or not is something that will no doubt be a big topic of debate
with him and his wife! If he does compete again, look out. I'll bet
there will be no sand in *his* wing.
If you fly on speedbar while trimmed fast, do NOT use
the main brakes! Don't use any brakes that engage the trailing edge,
even if just the outer 15%. Or if you do, experiment up high and by
flying through your wake. You may do it successfully a 100 times but, in
reality, be very close to a catastrophe.
Read the manual, if available, to learn about any dark
corners. But realize that, on uncertified wings, those corners may not
yet be fully explored.
A note for free flyers. I'm told by an experienced
free flyer that, in the past few years, they realize that the same
phenomena is true on their (non-reflex) wings--brake use on full
speedbar makes a collapse more likely .