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    • Gary B

      Meteorology For Glider Pilots

      By Gary B, in Articles,

      Sitting snowbound in the house waiting for winter to end my mind is wandering to the flying field on a nice sunny day! Part of the daydream is plotting how to read the weather for soaring.
      I used to teach trainee glider pilots basic meteorology to get them through the ‘Bronze C’ examination, as part of my Private Pilots Licence training I also had to take an exam on meteorology. The difference between the two exams is that the glider pilot one is aimed at understanding soaring conditions and the PPL one is aimed at keeping the pilot out of trouble.
      Chatting with other F3J pilots at competitions last year showed that there are different levels of understanding of the weather, perhaps it is a boring subject but knowing a few basics might help.
      Right then! Meteorology is a big subject but what we need to know as model glider flyers is manageable. Being able to read a weather chart is a very useful skill and probably more obviously, reading the actual conditions by looking at the sky at the flying site is the other.
      Unavoidably there are some technical terms but I will try to explain them as simply as possible as we go along! Apologies if this is ‘egg sucking’ for some, it’s aimed at readers with limited knowledge of the weather.
      Air mass
      This is the term to describe a very big lump of air! We say ‘the air mass is coming off the sea’ or ‘the air mass is stable’. The British Isles has a maritime climate (greatly affected by the surrounding sea), air can come from four general directions, Polar Maritime (Iceland, cold and wet), Polar Continental (Norway, cold and dry),  Tropical Maritime (Bay of Biscay, warm and wet) and Tropical Continental (France/Germany, warm and dry). There is a fifth direction now, Arctic, you can guess what kind of air comes from there!
      Pressure systems   
      We have two general types of pressure systems in the UK, low pressure (also known as a depression or ‘low’) and high pressure. Air always moves from the high pressure area to the low and the systems rotate due to Coriolis force (caused by the Earth’s rotation, the same force that makes your bathwater swirl down the plug hole!)
      Atmospheric pressure is measured in Millibars (mb), the worldwide average sea level pressure is accepted as 1013 mb.
      Fronts and troughs
      A front is the leading edge of an air mass, several hundred miles long and up to 100   deep, there are three types, warm front, cold front and occluded front.
      A warm front generally means dull, damp conditions with stable air (overcast and raining!) where a cold front will be drier with unstable conditions (very likely to be thermic).
      An occluded front is a mixture of both warm and cold fronts. The areas behind fronts are called ‘sectors’ so we say ‘cold sector’ or ‘warm sector’. German glider pilots call the cold sector ruckseiten wetter, literally ‘back side weather’. What they mean is the back side of the cold front where thermic conditions are best.
      A trough is an isolated line of low pressure, often associated with stormy weather.
      Lapse rate
      Sounds technical but it is just the change of temperature with altitude! If the air mass is wet (saturated lapse rate) the temperature will decrease approximately 1.5 degrees C per 1,000 ft of altitude and if the air mass is dry the temperature will decrease 3 degrees C per 1,000 ft. The way to remember this (if you really want to!) is that drei (dry) is German for the number three. These are very general numbers, the lapse rate varies depending on the actual humidity of the air mass.
      Under high pressure conditions there is often an ‘inversion’, this is where the temperature increases with altitude (the reverse of normality) and prevents thermal activity or limits its height. You can often see this as a purple haze where pollution is trapped in a layer.
      Dew point
      The dew point is the temperature that water vapour condenses into visible liquid water (i.e. a cloud!). This temperature relates to an altitude so we can work out what height the cloudbase will be (using lapse rates).
      Technical again but very simply imagine that the ground level temperature is 10 degrees C, the air mass is saturated (humid) so it has a lapse rate of 1.5 degrees. If the dew point has been predicted as 4 degrees then the cloudbase will be 4,000 ft (10 minus 4 equals 6, 6 divided by 1.5 equals 4).
      The difference between the ground level temperature and the dew point is known as the dew point depression, the bigger the number the higher the cloudbase. A high cloudbase indicates large, strong thermals, in the UK a summer cloudbase of 5,000 ft is fairly normal, Germany can be up to 9,000 ft (hotter land mass) and Australia can go to 12,000 ft plus.
      A related rule of thumb that works well for soaring prediction is the difference between the lowest overnight temperature and the maximum expected the following day, a cold night followed by a hot day usually means strong thermals.
      Orographic cloud
      Related to the dew point is orographic cloud, this is the mist that suddenly forms on slopes (usually after we’ve walked a mile to get there!). As the air rises up the slope it cools and if the dew point at your level decreases then cloud will form suddenly from nowhere, this can be quite dangerous for full-size glider pilots, the brief is to know what direction is needed to fly away from the hill and use the compass to do that (swiftly!).
      Insolation
      Not to be confused with insulation this is the amount of sunshine (Sol) that the ground is receiving, a south facing slope gets the sunbeams directly on it and heats up, often making the air rise up the slope without any wind, this is known as Anabatic wind. It’s enough to keep full-size gliders airborne in the Alps and can be used for light weight models on our smaller slopes.
      Cloud cover has a marked effect on insolation, if the sun can’t heat the ground then the thermals will die or decrease in strength. Late afternoon ‘spread out’ or ‘over development’ (becoming overcast) is common in the summer and is the curse of cross-country glider pilots. Out of interest cloud cover is measured in Oktas (eighths) so a half covered sky is reported as four Oktas.
      Diurnal variation
      Diurnal variation is a posh term used to describe the difference between day and night weather conditions that are affected by the sun. Obvious effects are the drop in temperature at dusk and a drop in the wind speed which free flight model flyers wait for when they are trimming.
      Hot air balloonists fly in the mornings and evenings, taking advantage of the effect.
      Perhaps bundled in with this is ‘maximum heating’, the time when the ground has got as hot as it is going to get, usually taken as 1 or 2 o’clock, slightly after the sun has passed its highest point in the sky (Zenith!).
      Weather charts
      The nice pictures provided by the BBC and Met Office are good enough for us. This one is from June 2012.
      Weather chart from the BBC

      Chart explanation and notes:
      Isobars: Isobars are lines connecting areas of equal atmospheric pressure, the closer they are together the windier it will be. On the chart they are the thin black lines with the millibar value written on them.
      Fronts: Warm fronts are marked in red with semi-circles facing the direction of movement, cold fronts are blue with triangles (icicles!) also facing the direction of movement.
      An occluded front is shown in purple with a mixture of semi-circles and triangles.
      Trough: A trough is shown as a thick black line (over France).
      From this chart I would expect good soaring conditions in Brittany and Cornwall.
      At the flying site
      Armed with all this gen we have looked at the charts and decided that it will be good for a trip to the field (lots of thermals) or slope (lots of wind and thermals!).
      There are still some weather related decisions to be made at the flat field flying site, ‘reading the air’ is often mentioned in model soaring books. What this means is taking a few moments before launching to work out where the best lift might be and formulate a plan to get there without losing too much height.
      On a good day there is a thermal under every cumulus cloud, a problem for us is that the thermals rise from the ground at an angle due to the wind so their source is probably quite a distance upwind, directly underneath a cumulus cloud is likely to be sinking air. It might be worth having a look above or downwind to see if a cloud is sitting on a thermal column that is much closer. Quite a guessing game but it’s the part of the sport (F3J) that I enjoy the most and still have a lot to learn.
      The strength of the wind can vary throughout the day, probably the biggest effect I notice is in the lower end of the landing circuit, too much spare height with no headwind makes hitting the tape tricky! I have watched many full-size gliders land downwind, quite remarkable at an airfield with two very dayglo orange windsocks!!
      I hope this article is useful, there is obviously a lot more to it, meteorology is covered in the older soaring books by Dave Hughes and George Stringwell etc, not always easy to get hold of nowadays. A very good book is ‘Meteorology and Flight’ by Tom Bradbury, available from the British Gliding Association online shop or Amazon etc.
      If all else fails follow the birds, there’s a friendly Red Kite at my home field!
      Cheers
      Gary Binnie

    • Austin

      Tribute to Al Wisher

      By Austin, in News & Information,

      Al “Blue Beast” Wisher
      I first met ”Big Al” shortly after I joined Basingstoke Model Aircraft Club (BMAC)  around 1973 or 74.  I had built a Monterey 100 inch soarer (Radio Modeller Plan). Al had agreed to teach me to fly on Basingstoke new common.  I remember that first short trimming flight well. I gave the model a reasonable throw down the slope on the common, it flew very well and landed at the bottom.  I retrieved the plane and returned to where Al standing was with the Transmitter. “Now reverse the elevator” he said. Yes he had flown the Monterey perfectly down the slope reversing the elevator stick direction to compensate for my error.  Over the years I have taught a fair number to budding new pilots to fly, the first thing I do to this day before that first launch is to check the elevator for correct direction of movement, something’s  you never forget.
      At the BMAC AGM that first year Al who was Club Chairman was re-appointed. However, there were no volunteers for the Secretary’s job (sounds familiar).  Al simply looked across at me and said I helped you to learn to fly, so its your turn to help me, you’re now the new Club Secretary.
      I'm sure many of you will know that prior to flying radio controlled gliders, Al was a free flight champion having a number of “A2” designs published including the Wishbone, published in the May 1964 edition of Aeromodeller.  With the advent of proportional radio control systems Al turned to RC gliders, becoming one of early founders and promoters of the British Association of Radio Control Soarers.
      I believe his first model was a 2 meter model from a well known German company. He entered and flew in his first competition (BARCS Southern Area), without any prior tuition or practice and yes he won.
      Al was at that time employed as a representative by a large company of shop fitters. He would often be up early in the morning and drive to Birmingham for a 9am meeting, thus enabling him to be back in Basingstoke by early afternoon.  He would then be out as usual on Basingstoke common with his plane and bungee practising in all weathers.
      Al was probably best known for his large blue coloured rudder/elevator competition soarer called “Blue Beast”. BMAC used to hold a static competition in April each year to see who could produce the best looking model in each category. Well Al brought along this big blue coloured machine for the glider category, when it was assembled somebody remarked “that’s a big beast”. Hence the name of “Blue Beast” came about.
      Al formed his own competition team to fly in the BARCS league. This comprised Ken Glynn, Norman Elliot (who passed away this August),even persuading Norman to move from Mitcham to Basingstoke to be in the team,  Peter Lee (also deceased), myself and later on Adrian Lee to fly against Chris Foss, Ricky Shaw and many others in the BARCS league. At times Al would fly in the Midlands league, taking his wife as timer/spotter leaving his son Paul to stay with me and my family for the weekend.
      Al eventually moved up north, I assume with his job and he eventually settled in the Bolton area.  By then my job was taking me to South Asia for long periods of time so I lost touch with him. I did however manage to make contact with Al in September this year as I was at the time writing an article for the Thames Valley Silent Flyers (TVSF) magazine about Norman Elliot who flew in free flight competition with Al many years previously.
      Declining health over the last ten years meant that Al was unable to fly as much as he would have wished, and he died in mid-December, 2012. He leaves a legacy which means that he will not be forgotten.
      Clive Learwood
      ThamesValley Silent Flyers

    • PeteMitchell

      The Impossible Repair

      By PeteMitchell, in Articles,

      It’s that time of the year when enforced hibernation makes many of us think about repairing some of the previous season’s damage.  Having had more than my fair share of dramas over the years, I have come to realise that more often than not, what seemed like a total right off at the time is with care, repairable.   Every disaster is different and not all moulded models are the same, but here is what I did to rebuild a wing tip.
      The model is an Electra F5J 3.7 mtr thermal soarer.  It’s  construction is the usual hollow moulded epoxy/ carbon/foam/glass sandwich, and is of a fairly light weight.  The tip in question was almost totally destroyed in the arrival when my radio link failed, which was traced to a faulty Lipo  The model rolled inverted and quickly disappeared behind trees about ¾ mile from my flying field. I was fortunate that apart from the fuselage tail boom being broken, this was the only significant damage.
      To start I cut away as much of the remaining damage as was needed to enable me to decide if a repair could be done. This photo shows my first attempt to piece the bottom surface together with scraps of thin carbon. This did not really work.

      As the main spar and the aileron spar had to be replaced I decided the best repair would be a ‘traditional’ balsa rebuild, but with carbon reinforcement. I started by making a paper template from the other good undamaged tip. The template idea was also dropped as the work progressed.

      As the repair progressed, the missing moulded surfaces were replaced with balsa sheet and I decided to make the tip from foam. I thought this was the only way I could reproduce all the curves. I cut a rough shape from blue foam and epoxied it, with carbon pins, to the rebuilt tip.

      This shows the underside as I start to sand the repaired area, and foam tip, to shape.

      Once the repair had been sanded to an overall smooth finish I wanted to complete the repair without adding any more weight than was unavoidable. I thought that to try to replicate the models colour and finish was a waste of effort and decided to use Textreem spread tow carbon. This is the material used in many of the lightest thermal soarer’s.  
      I coated the surface of the repair with wing skinning epoxy and laid the cloth on to it. The epoxy soaked through the cloth and I removed as much as I could by much blotting with kitchen roll paper. Once I had the epoxy evenly spread through the cloth and it all looked ‘dry’ I covered the completed area with  a thickish polythene cut from a rubble sack. I then carefully pressed this down all over onto the carbon with fingers and the edge of a credit card. Once again the epoxy that remained came through the cloth to the surface.
      To finish off I covered the job with as many magazines and weight as I could balance on the work bench and left it overnight to cure.  The picture shows the underside after sanding and trimming.

      I covered the underside first because the tip needed to be strong enough to allow the top surface to be sanded to its final shape. Once this was done the same process was followed which can be seen in these last two photos.

      The model had this repair plus a smaller one on the other tip and to the fuselage boom. The total gain in weight is approx. 40g which I thought was pretty good. The repaired tip is approx 25g heavier than the other, but as far as I could see it did not show in flight.

      If you are in a similar situation, I hope these few words will help you make a start on that ‘impossible’ repair.
      Peter Mitchell
       
       

    • Austin

      Radioglide 2012 Report & Results

      By Austin, in Radioglide,

      Radioglide was again affected by the weather, although we did enjoy 3 full days flying out of the four offered by the extended bank holiday. This was slightly frustrating because the normal time for the event, end of May weekend enjoyed beautiful weather. However this year the bank holiday moved back a week so we, along with much of the rest of the Nation, suffered a very wet Sunday, forcing the cancellation of the Multi-launch event. This was unfortunate as it removed an opportunity to see how the electric launched gliders (now with a 150 meter height limiter cut off) performed relative to the winch launched pure gliders.
      Saturday started off with low cloud and light drizzle but the rain stopped quickly and the cloud base lifted enough early on to allow a prompt start to the F3K league competition. This  event shared the field with Electric Launched Gliders (ELG) which had to wait for conditions to improve and allowed us to marvel at the launch heights now being achieved by the DLG’ers.
      I can’t give a detailed report on F3K as I was on the other side of the field but 11 pilots flew 8 rounds of the various tasks available. One score was dropped for the final placings, with Richard Swindells inevitably taking the win with 6962 points followed by Martin Halston and Simon Jones.
      After the delayed start for ELG, good air was to be found and most slots flew out the ten minutes. Indeed almost uniquely for an ELG competition there were no re-launches whatever during the event. The entry was very low for a national status competition however the standard of flying was high – the winner Cliff Hannam returning a perfect score of 6000 closely followed by Peter Allen who might also have achieved a 6000 score if he had not, by mistake, touched his motor control on final approach so turning that flight into a zero score. All “Open Class” ELG entrants flew moulded models, Pike Perfects being much in evidence, used by the many of the competitors, including Cliff Hannam, with Storks, Supras and Pulsars in evidence. The shared field (with F3K) worked without any problems.

      ELG Prize winners L -R Robin Sleight (Restricted Class) Peter Allen (Open runner up) Cliff Hannam (Open Winner) Terry Pelling (Open Third)
      The F3J competition on Monday enjoyed the best of the Bank Holiday weather and also had the largest entry.  The competition was one of the “National” status events for the BMFA F3J team selection league but the bulk of the entrants were the regular flyers in the BMFA Southern group of F3J events.  With a modest northerly breeze, conditions were good albeit cold for June and virtually all slots flew out.  
      The competition ran along smoothly and the scheduled five rounds were completed in good time to allow a two slot fly-off of the top five pilots going into the fly-off were Graham Wicks, Colin Paddon, Chris Glover, Peter Allen and Mark De Vall.  As always the fly-off produced some outstanding flying and the old master of such events, Colin Paddon beat Graham Wicks by a small margin to once again get his name on the Radioglide premier trophy.
      Without exception as one would expect, all models were moulded. Neil Jones was campaigning the new Pike Perfection from Samba Models. Samba must employ someone well versed in English language superlatives as they have, with the Pike series, progressed from the Pike to Pike Plus, Pike Superior, Pike Perfect and now the Perfection!  An interesting model with an ultra thin, tall fin and rudder, the latter being unusually large. The latest Xplorers, Tragi Clusters, Supras and Maxas were all on show, with a smattering of older Shadows, Graphites, Starlights  and Experience Pros.

      F3J Fly Off  L – R Colin Paddon (Winner) Graham Wicks (Second) ‘Fozzie’ Devall (Fifth) kneeling  Chris Glover (Third) Peter Allen (Fourth)

      Colin Paddon, Winner F3J
      The forecast for the 100S event on the Tuesday was also far from promising with rain forecast in the early afternoon and a 12 to 15 mph southerly wind blowing. However, urged on by CD Peter Allen, a very prompt start was made to the flying and a light drizzle had only just started by the time of the final two slots of round five. These final slots were completed without problems but by then it was obvious that serious rain was on the way (the forecast was very accurate!) so the round scores were used to calculate the final positions.  
      In spite of the overcast sky, many slots were flown out – primarily due to a wave type of lift rather than normal thermal and some of that lift was quite powerful but good penetration was essential to reach the area where the wave lift might exist. As usual with 100S competitions, Trackers were much in evidence but there was also a range of other models, all proving competitive including a couple of Eliminators as well as a Chieftan flown by Garry Binnie and Sagitta by Robin Sleight providing some ‘Classic’ competition.  
      In the end however both the first two places were eventually taken by Tracker flyers with Radioglide newcomer Mick Thorpe taking first place and narrowly pushing Alan Morton into second spot.  The many outings in the Peterborough series of 100S events obviously does help the scoring of flyers such as Mick and Alan, relative to many of the other competitors who only fly 100S models on an infrequent basis – could be that there is a message most of us could take from that; the more you fly a specific class, the better you will tend to be!
      So all in all not a bad weekends flying for the many, made possible by the efforts of a few. Peter Allen once again secured the field for us, along with toilet facilities, took in the entries, laid out flightlines as well as CD’ing 100s. Neville Warby and his magic van were there with equipment for the 100s comp. ‘Uncle’ Sydney Lensenn bought his quiet, polite and efficient tones to running the F3J event, matrixed by Mike Raybone and was very ably assisted by Gill Glover in the tent, scoring. Where would we be without the many ‘better halves’ who help out at competitions. Simon Jones CD’d the F3K event assisted on scoring by Tony Beckett. We hope this marks the return of F3K to the Radioglide calendar. And last but not least Robin Sleight, who ran the ELG event and kept an eye on everything throughout the weekend.
      ELG Scores
      *Flying a “Restricted Class” Model (2 M Span)
      Note all models flew with height limiters (no 200W/Kg models)
      All the Open models used the RC Electronics Height Limiters, CAM limiter in the 2M model
      table.tableizer-table { border: 1px solid #CCC; font-family: Arial, Helvetica, sans-serif; font-size: 12px; } .tableizer-table td { padding: 4px; margin: 3px; border: 1px solid #ccc; } .tableizer-table th { background-color: #4297C9; color: #FFF; font-weight: bold; }
      PosNameDrop 1 TotalRND 1RND 2RND 3RND 4RND 5RND 6RND 71Cliff Hannam60001000100010001000803100010002Peter Allan59411000100094110001000100003Terry Pelling583598492999898494053110004Ray Gadene5797990978722100088110009485Glyn Chambers577694196867095210009269896Terry Weeks5688961100010009567997919727Martin Bell5507992761100093264982210008Graham James5068100056673258610008359159Robin Sleight 2M*4699636829921670672663944F3J Preliminary Rounds
      table.tableizer-table { border: 1px solid #CCC; font-family: Arial, Helvetica, sans-serif; font-size: 12px; } .tableizer-table td { padding: 4px; margin: 3px; border: 1px solid #ccc; } .tableizer-table th { background-color: #4297C9; color: #FFF; font-weight: bold; }
      PosNameRaw ScoreRnd1 DurRnd2 DurRnd3 DurRnd4 DurRnd5 DurPenlty1Wicks, Graham4990.4995.3100010001000995.102Paddon, Colin4973.510009831000995.599503Glover, Chris4830.2990.21000986.3999.9853.804Allen, Peter4781.81000996.9993.81000791.105Devall, Mark4760.3984.11000790.2986100006Osbourne, Ozzie4757.3998.2781.51000985.3992.307East, Dave4640.1982.11000796.5994.586708Dart, Kevin4638.61000644.7993.91000100009Beale, Kevin4629.6998.4882.9774.8999.4974.1010Guerrier, Austin4555.910001000865.4997.8692.7011Duff, Ian4497.6999541.5983.3973.81000012Jones, Neil4486.9862.8993.2856.41000774.5013Binnie, Gary4472.7979.7949.21000965.4578.4014Dickenson, Bob4419.7867.6894.9657.2100010003015James, Graham4249.1961.1863.1621.9988.8814.2016Warby, Neville3981.2862.6723.6782.5923.1689.4017Borowski, Andre3972.51000824.1730.7998.3419.4018Philcox, Cengiz3845.1555.6950595.8801.1942.6019Pelling, Terry3984.6420.3846.81000879.583830020Boorman, Colin3612979.6578.9553.3993.7506.5021Sleight, Robin3426.1540.3814.4864.5559.3647.6022Lipscombe, Alan3358.9648.4562.3776.4731.7640.1023Thorpe, Mick3594.8652.4923.3560.2980.6478.330024Goddard, Ken2979.4927.5411.5538.5464.3637.6025Satinet, Tom2898.50698.2774.6726.5699.2026Hannam, Cliff2664.30673.4990.9010000F3J Fly Off Scores
      table.tableizer-table { border: 1px solid #CCC; font-family: Arial, Helvetica, sans-serif; font-size: 12px; } .tableizer-table td { padding: 4px; margin: 3px; border: 1px solid #ccc; } .tableizer-table th { background-color: #4196C8; color: #FFF; font-weight: bold; }
      PosNameScoreRnd1 DurRnd2 DurPenlty1Paddon, Colin20001000100002Wicks, Graham1925.3982.4942.903Glover, Chris1522.4593.8928.604Allen, Peter1494.9614.6880.305Devall, Mark1298.5583.4715.10100s Scores
      table.tableizer-table { border: 1px solid #CCC; font-family: Arial, Helvetica, sans-serif; font-size: 12px; } .tableizer-table td { padding: 4px; margin: 3px; border: 1px solid #ccc; } .tableizer-table th { background-color: #4297C9; color: #FFF; font-weight: bold; }
      PosNameScoreRND 1RND 2RND 3RND 4RND 51Mick Thorpe4980.810001000984.6996.210002Alan Morton4946.110001000946.1100010003Jon Hullett480010001000100080010004Ken Goddard47831000998.1897.9940.2946.85David Leech4727.7770.210001000992.3965.26Al Lipscombe4422.9876.8975982.8598.1990.27Nevillle Warby4364.6720.5864.61000893.6885.98Graham James4221806.6886.4100010005289Glynn Chambers4048.7666.71000852.5826703.510Robin Sleight4044.1807.7646.2942.2100064811Mark Devall3968.7745.3935.1624.2664.1100012Terry Pelling3940.7407.1637.61000100089613Bob Dickenson3888580.2992.3779.7671.2864.614Robin Sleight (Classic)3707.1661.9818.8869.2591.276615Gary Binnie (Classic)3356.2605.6978.9700472.4599.3F3K Results


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