Monday, September 15, 2008

Sprogs

A little while ago this great insight into hang glider stability was published on You Tube. If you are a Hang Gliding nut then it is fascinating :
link : Gerolf on Sprogs

I have played with my own sprogs, with varying results, and never feeling very comfortable about doing the adjustments and following test fly. The video inspired me to go buy a $40 digital level and make some measurements.

First set the glider up VG full tight and get the base tube level. I think still air is probably necessary. I was surprised how big of a wedge was needed to compensate 1° of tilt.
Get the keel level.Take the measurements. For me the inside left and right were both 4.3° Outside left was 6.2° Outside right was 6.6°.
Note: results for litespeed RS3.5
I will get to measuring a couple more litespeed S4 models soon.

2 comments:

Mark Dowsett said...

Hi Ben - what is the make and model of the leveler you got? And what sort of store did you pick it up at? Would a Home Depot carry that sort of thing?

I'd like to get one.

wind burns & earth turns said...

Hi Mark,

The digital level I got is made by Husky the 20 inch model.
It was about $40 at Home Depot.
I just measure my old Litespeed S4 and found it to be horribly asymetric and low. I was measuring just infront of the collar where the wire comes in - but I don't know if that is in line with Gerolfs technique. Depending on where one measures the results can vary 1.2 degrees.