US Hawks Hang Gliding Association

http://jmrware.com/articles/2008/leverlink/LeverLink.html
A spectacularly interesting idea for control enhancement by Jeff Roberson.
Discussion welcomed.
Especially by people who fly BFGs.    
You know who you are.    

Very interesting and a good idea, in my opinion.

However, I don't think he may be aware of the solution we used before the floating keel pocket and crossbar became available on manufactured gliders and we wanted to improve our glider's roll control and keep it flying a few more years before upgrading.

We made our flex wings roll easier by running a cable from wing tip to wing tip which passed through a pulley that was mounted in front of the nose of the glider. When the pilot moved to the right, let's say, it would weight the right wing panel, forcing more billow, and pull that right LE tip inward which would pull the left wing tip outward via the cable and that would tension and flatten the left wing panel. This greatly improved roll response to weight shift.

This was used by individuals, including myself, to make an old style flex wing, without a keel pocket or floating crossbar, roll easier and preform more like a more modern flex wing that did have these features. It would now seem that his method then takes the modern glider a step above the keel pocket and floating crossbar roll performance, especially for tight sail competition style gliders. It is like a combination of our old tip to tip cable system and the newer keel pocket and floating crossbar.

Before I put the tip to tip pulley cable on my WW SST it was sluggish in roll response. After I built and installed the pulley cable system it was much improved.

I bring up the tip to tip pulley cable because I think it was an important step in the improvement of flex wing roll control that has been lost to hang gliding history and it worked quite well to improve our old non-floating flex wings.

Since I got back into HG, recently, I've wondered what the "tip to tip" pulley cable system would do for a modern floating sail glider. Hmm.....I might try it on my Condor 330.

Frank Colver

First consider a French Connection mounted parallel to the crossbar.
The more complex a system, the more that can go wrong.
Something going wrong in roll is harder to correct than something going wrong in pitch.
And likely more disastrous.
I have never had a problem with a French Connection in pitch.
But I've never tried one in roll, although others have with success.

The beauty of the "tip to tip" pulley cable system was that if it broke you were just back to what you had been using before making the mod. It was so simple that sticking would not be a problem because even if the pulley wheel froze, and wouldn't turn, the cable would still be able to slide across it. If somehow the cable came off the pulley wheel, then again, you would just be back to the original glider, with this slack cable going from tip to tip.

I never did have a problem with it but it was more stuff to consider on the glider. So far. I have not seen any photos I might have taken showing the system. Also, I don't remember who originally told me about this method but it sure didn't take me long to adapt it to my SST after hearing about it. After that I had a lot more roll authority.

My first test flight with this system was at Escape Country.

I like things that can fail without causing disaster.

Frank

Rick Masters wrote:...http://jmrware.com/articles/2008/leverlink/LeverLink.html
A spectacularly interesting idea for control enhancement by Jeff Roberson.
Discussion welcomed.
...

I am the author of that article and originator of the LeverLink idea. Thank you for your interest!

I still think this is an exceptionally good idea and I'm surprised the designers in the industry haven't recognized its significance and run with it. Every couple years or so, I google: "leverlink hang glider" and see if anyone is discussing the idea - its mostly been ignored. I did miss this thread, but have now found it. Thus, I registered as a "Hawk" and here I am!

Jeff Roberson
Monroe, UT

p.s. Before discussing any specific ideas, I would humbly ask that one first come up to speed by reading what's already been discussed, particularly the three threads that I linked to in the "Forward" section of my article. e.g. It is my position that the roll portion of the double french connection "pif-paf" does not employ the Leverlink principle (as I understand how it was mechanically connected to the glider - I never got a definitive answer as to that question).

Hi Jeff (not "Jim" ... thanks Scott),

Welcome to the U.S.Hawks where our new motto is:

Come on in for the Rock 'n Roll ... stay for the freedom and the flying.

I don't know if Rick is doing any design these days, but I do know that Frank Colver is actively working on a new design intended to be easier for beginners to get started. Frank is USHPA #7, so he goes way back in the sport. He's trying to keep his glider as simple as possible and had shortened the span to make it easier to control roll at launch. You might try to contact him as he gets closer to building the first full scale glider.

Here's a topic where Frank began discussing his design:

    https://ushawks.org/forum/viewtopic.php?f=2&t=2967

You'll find some unfortunate differences of opinion in that topic (politics), but It's a good place to start. Maybe Frank can incorporate your idea to get his desired roll response without sacrificing so much performance.

Either way, thanks for landing here at the U.S. Hawks.   

Ah, . . . Bob means Jeff.

wingspan33 wrote:Ah, . . . Bob means Jeff.

Thanks Scott. I added the correction to my post.