[Free]

Try this: go upright, grab the downtube about 2/3 of the way down. Pull your body over as far as possible and kick your legs out beyond the downtube plane. Not only can you do this quicker than when prone, you can get your effective weight further away from the midline than if prone.

Try it sometime.

I believe I have used such a technique a long time ago..
It was newish Hang 3, first tow/flight landing a new Axis 15 and caught a little rotor off a levee, trying to land close for a re-tow.
I was upright on final and I had to radically hug the downtube because I was not getting the roll response I needed.

Seemed to me at the time as a good reason to stay on the basetube longer (and not getting behind the levee)instead of needing such a spastic emergency response.

I also remember another spastic leg kick to the outside of a low turn to final in order to complete/level the turn.
It worked but it was not pretty. Had gone to the downtubes early because worries of a new pod harness...
It was a set up for landing downhill at Hensons to be close to the ride back up the ridge.
Convenience seems a common theme/problem here..
I can't remember why we weren't landing in the bowl on a north day.

[ZackC]

...without going to the trouble of reviewing or thinking I'd say that you probably DO have more roll authority up on the downtubes - FOR ANY GIVEN AIRSPEED. But you don't see people at aerobatic competitions going vertical and grabbing high to roll hard - you see them staying prone and stuffing the bar to make the glider REALLY responsive.

http://www.kitestrings.org/post172.html#p172

Zack

[Bob Kuczewski]

Rick, thanks for stirring this up. I had mostly given up on the people here.
I had hopes for reaching out to Bob, with a simple physics conundrum but even a blatant
physics impossibility was not enough to break through the years of government indoctrination.
Steel core building can collapse at the speed of gravity if the government says so.
One physical impossibility is not enough evidence that the truth is not being told.

Hi Warren,

I took the time to actually write a computer program to help analyze the data from the video that you felt was the "smoking gun" regarding the collapse. I posted my analysis, the program itself, and my results here:

http://ushawks.org/forum/viewtopic.php?f=2&t=881&p=3861#p3860

In fairness to me, I've spent a lot of my own time trying to diligently follow your arguments. But as an engineer, I can't say that I've seen any "physical impossibilities" here. The data is consistent with a collapse ... in my best opinion. I'm sorry, but you just haven't provided anything to convince me otherwise.



With regard to roll authority, I think it's much harder to shift your lateral center of mass quickly in the prone position than in the upright position. When you're upright, your arms are able to directly shift your center of mass by pulling. But in the prone position, the center of mass must be moved by differential pressure of the arms where the center of mass (hips) has the greater mechanical advantage because it's located so far from the center of torque (midpoint between hands on the base tube).

Actually, that last sentence really clarified it for me. Imagine a crescent wrench trying to turn a bolt. There are four elements there ... the bolt to be turned, the jaws gripping the bolt, the force applied to the wrench, and the distance between that force and the bolt (sorry, but I don't have time to draw a diagram right now).

Now imagine that the crescent wrench is trying to push your hand by twisting against the bolt. That's what's happening when you try to use your arms (jaws of the wrench) against the base tube (bolt) to twist your center of mass (hand applied to the wrench). You can see that your hand on the crescent wrench has a tremendous mechanical advantage over the jaws at the bolt. So the jaws at the bolt would have to work very hard to be able to overcome the force on your hand. That's why it's much harder to shift your center of mass (hips) using your arms against the base tube when prone.