Basejumper.com - archive

A newbie posting in the technical forum. Please be gentle...

I have a general question regarding line length. Why are suspension lines as long as they are? I don't mean the control lines, but all the lines going to the canopy. I imagined that making these as short as humanly possible would reduce the chances of a line twist or entanglement, but I guess this isn't the case, and there must be legitimate reasons for why lines are as long as they are. Would someone mind explaining these to me, or point me someplace where I can read more about this?
Thank you

You're absolutely right.

The drawback is that reducing line lenght for a given canopy also reduce the projected area, because the canopy becomes more arced (the arc radius become smaller).

If you're really interested into technical aspects of ram-air canopies designing, there's a huge quantity of valuable information on www.paraglidingforum.com

here are some links:

How and why does the arc of a wing affect its performance?
http://www.paraglidingforum.com/viewtopic.php?t=9015

Aspect Ratio (flat & projected)
http://www.paraglidingforum.com/viewtopic.php?t=12600



edit: add links

Long lines also make the canopy less prone to diving turns. Think of swinging a very short pendulum or a very long one. It's much harder to get a long pendulum out to the side, which corresponds with a diving turn.

Michael

Also note that BASE gear manufacturers have come to various conclusions on this issue. When Basic Research (now Apex) re-designed the FOX into the Flik, the shortened the lines quite a bit (about 3 feet on my sizes). But when Consolidated Rigging (still Consolidated Rigging) designed the Ace and Blackjack, they went the other way, making the lines longer, per size than their previous canopy (the Mojo).

does this mean the flick opens faster??

No. Without getting into a debate about this and that canopy and manufacturer, I think that the pressurization characteristics are impacted more by other things (like trim angle, vent configuration, etc) and that line length is only one small variable that goes into overall pressurization characteristics (which is only one thing that goes into a "faster" or "slower" opening).