UK RASP Ridge Day Tool: the hang gliders’ version
Back | HomeI’m interested in compiling a version of the ridge day tool for hang gliders (and a third for paragliders — can’t really leave you out 
).
I personally think the ridge day tool is the best thing since sliced bread but I’m not sure it’s used that widely.
However I have a friend who hang glides and apparently this site is quite well known amongst them, so I’d like to extend the ridge tool to cover them too.
So if you have a favourite ridge and would like a tool that can scan seven days of forecasts and tell you when that ridge may be working, what I need from you is:
- Site name
- The lat/long in decimal form (e.g. “52.3675,-1.2433”), to four decimal places
- The wind speed range (in knots) and the wind direction range the ridge works in (e.g. “300-350”)
I have a suspicion that the wind speeds will be fairly fixed — something like 8-15 knots for paragliders and 10-20 for hang gliders? Do educate me though!
Either leave a comment with the info below or use the “e-mail me” link on the left.
Hi, it would be really useful to extend your ridge day tool for Hg & PG pilots,
I fly mostly in S wales so you have a couple of our main sites covered ( the Bluff & Pandy, ) but extending it to the Blorenge :
51º 48.2’N
3º 03.1’W
and is flown from 290º - 135º. Ypu already have the appropriate windspeed ranges - I presume you make due allowance for compression at take off, as this is the critical speed to determine if the site is flyable. Our main westerly is Merthyr
Latitude: 51º 43.4’N
longitude: 3º 20.1’W
which is flown 225º - 293º.
See http://www.sewhgpgc.co.uk/sites/ for our sites. We could link from this to the relevant RASP ridge day tool page
Thanks, that’s useful. The person who developed the ridge tool (who likes to stay anonymous) is looking into setting it up to scan for a range of wind speeds, rather than meeting a simple minimum — no point reporting “ok” for a day if the wind is actually 40 kt!
Speed-up over hills *is* modelled by the model, but probably not enough as the model only has data points every 4 km — therefore fine terrain detail is lost, and the compensation is not ideal.
One day — maybe in a few years — it might be possible to model the UK at a resolution of 2 km, which would be a distinct improvement. There’s a lot of technical hurdles though.
I was a little surprised and delighted to find that both Shobdon and Wapley were working today. My glide computer calculated the actual wind a bit above the hill top (around 1500 amsl) as 8-10 knots 350 degrees true and this matches the ridge tool prediction closely. The ridge tool was not showing any soaring for these ridges today and that is not surprising because when I specified the wind strength and direction for these ridges to you I specified 15 knots minimum. When you think about it you need less wind strength when it is directly on the hill and more when the wind is oblique. Does the ridge tool allow for this?
I think perhaps we could fine-tune the parameters for Shobdon & Wapley to specify a lower minimum wind speed of 12 knots rather than 15. I think that they only worked today in 8-10 knots because the air mass was particularly unstable and I wouldn’t want to rely on them working below 12 knots as a regular thing.
Perhaps the ridge tool can vector the wind speed, it already knows which way the ridge is facing. So a simple calculation on the total wind speed would yield new minimums for the ‘onto ridge’ component.