Graham Jones has again arranged for a PSC summer Curry night at the Sun Inn in Chipping on the 14th August 2015 at 7:30pm. If you would like you go can you please let Graham know, either by the Facebook event or via email to gkjones@btconnect.com.
Last years event
9 March at 20:00
Boatyard Inn. Bolton Road Riley Green. PR5 0SP.
Pre Flight Planning. Dave Evans.
Subjects to be covered.
Weather assessment.
Flying site assessment.
Reason to fly.
Task planning.
Flying with others.
XC Planner.
Instruments.
Recording and entering flights.
Planning for competitions.
It is now getting flyable at last!
The time has come to warn newcomers that spring thermals can be rough, and that particular care is needed when flying near to the hill on cold, clear bright days. These days are when the condition of the air favours small, fast moving thermals that can tip your glider to angles that you may not have flown at before.
Avoiding the technicalities of thermal formation and behaviour you must be aware of the following:
When a bubble of air starts to rise, a circulation is set up in its outer “skin” by the combination of friction between the rising air and the air surrounding it and convection caused by the warm thermal being cooled by contact with the cooler air around it.
In addition, as the warm air rises, cooler air descends to replace it. Thus, loosely speaking, there are three areas to concern us.
A. In the middle where the air is rising
B. Around the edges of a thermal, where the air is turbulent and where the circulation causes the net upward flow to be much less then in the core
C. Where the airflow is downwards.
So, when you fly along a radius into a thermal that is ‘out in space’ you will usually feel sink first, followed by the turbulence with some lift then the really useful up flowing air in the middle.
What happens when this thermal up the face of a hill. The shape is probably distorted as shown, and depending on the gradient of the hill, the thermal may break away from the face part way up.
In the occasional extreme case, we can have a situation as
above where the circulation at the ridge side of thermal may be augmented by downward flowing air being sucked into the bottom.
When the thermal is large, your glider may be wholly or mainly in one of the regions A, B or C with a fairly gentle transition from one to the other. When the thermals are small your glider may span all three of these regions.
If you are flying close to the ridge and you pass tangentially through a thermal, as shown above, your glider will be tipped violently towards the hill. Even if there is no down flow between the thermal and the hill, the first time you experience strong lift under one wing tipping you towards the ridge you will probably wish you had tried golf instead.
The above information has been condensed from articles by John Klunder, Bill Walmsley and Jonathan Gill.
The Thames Valley Hang Gliding Club’s annual safety and repack event, The Big Fat Repack, is on Sunday 15th March 2015.
The Big Fat Repack features:-
Click here to book now; if you want to see more checkout the videos of past events and our website. If you have any questions please feel free to contact us.
There are still plenty of places. Everyone is welcome; club members, BHPA members and even non BHPA members; please encourage your friends to join us. Non BHPA pilots will need to purchase a day membership at £15.
Hope you see you on the day.
Best regards,
The BFR Team
