Video

[deltaman]

2004: It seems to me that Davis is far forward for a 2 points (as his anchor point on a double surface) http://ozreport.com/pub/fingerlakesaccident.shtml

How will I avoid this problem in the future? I will tow only from my shoulders. I won't let the tug pull me forward quite as much (just enough to clear the barrel of the release). If I'm towing with a double V-bridle, I will barely pull in at all, in fact I will lock my arms with the bar at around my face and make sure that I am not pulled forward too much (get in the position where the bar would be to be between minimum sink and best glide).

Looks like you guys just forced the glider off the cart too soon. It doesn't appear that the keel has lifted off the support at all when the decision is executed.

We didn't force the glider but maybe we leave the cart too soon. No wind and a slow tug acceleration.
I think
1- we had a bad angle on the cart too
Single surface are tricky. The angle should be set with the 2nd or 3rd batten, wing already inflated and (big) keel pocket tight ..and not relative to the keel angle.
2- I told the student: "don't pull" just after leaving the cart ..and I think I did it !!..

[Tad Eareckson]

It seems to me that Davis is far forward for a 2 points...

He is.

How will I avoid this problem in the future...

What he WON'T do, under ANY circumstances EVER, is use a release which allows him to abort a tow in an emergency situation - which is just fine with me.

I told the student: "don't pull" just after leaving the cart ..and I think I did it !!

Oh well, people have gotten in a lot worse trouble by pushing.

[deltaman]

http://www.youtube.com/watch?v=MlIGsgNFRWM

[Tad Eareckson]

Yep.

http://www.kitestrings.org/post2207.html#p2207

Comes out of the cart at Mach 5 and SLAMS into the propwash. Towing out there in the desert, like it or not, you get to see it and see it in a big way - big ol' cloud of dust and rocks.

And you're wondering why he breaks his weak link???? Are you kidding me?

Think about it. He's going a million miles an hour under huge (relatively speaking) line tension as he comes blazing out of the cart - struggling to stay down - and slams into turbulent air. Hell yes he's going to break his weak link. That's what it's there for!

He subjected it to massive loading. (The shock loading a weak link sees as you hit the propwash is far greater than people appreciate.) That's why he has it... it's doing its job.

And he's not using a fin.

[deltaman]

[miguel]

Not poking fun but not understanding the concept.



Propwash extends in a diminishing continuum starting at the prop and extending rearward until it diminishes some distance behind the aircraft.

Downwash from the wing hits the ground and becomes more turbulent and this turbulence extends rearward also diminishing with distance.

Seems to me that the propwash/downwash turbulence should be pretty uniform at the cart from the cart level to about where the weak link breaks.

Seems that the weak link is too weak and needs to be strengthened.

Flame away, I have my asbestos britches on.

[Tad Eareckson]

Not poking fun but not understanding the concept.

Hate to contradict you but you're understanding the concept just fine.

Seems to me that the propwash/downwash turbulence should be pretty uniform at the cart from the cart level to about where the weak link breaks.

I've towed behind 914 Dragonflies a zillion times and if I ever got hit by anything it wasn't at a detectable enough level to have created a memory.

And compared to the crap you have to fly through to get to altitude on a good thermal day...

Even with a loop of 130 pound Greenspot on a two point bridle which - AT BEST - puts Yours Truly (320 pounds) at under 0.8 Gs (off the bottom end of the FAA legal range) you can get beat up badly enough on tow to really feel it the next day.

Seems that the weak link is too weak and needs to be strengthened.

Yeah. It needs to be quadrupled. But don't ever say that too loudly if you have any future plans of flying at a US aerotow park or wanna be able to post on the Jack and/or Davis Shows.

Flame away, I have my asbestos britches on.

With the possible exception of Allen, you have no enemies here on this one.

[Zack C]

In case you're wondering why he brought prop wash up to begin with...
http://www.kitestrings.org/post2207.html#p2207

Zack

[miguel]

thanks for the 411.

[spark]

http://www.youtube.com/watch?v=RYP9Rkh-YbI
Scooter Tow
hanpara - 2011/01/15
2011.01.08
dead