The Wire April 1997

Issue 7

April 1997

The Newsletter of Stratford Gliding Club


Club Diary

The following events are planned for the 1997 season:


28 April 7-day flying starts
5 May Bank holiday
19-23 May Sutton Bank
21/22 June Longest Day
7 July Club flying week
4 Aug Busy course week
11 Aug Club flying week
25 Aug Bank holiday
12 Sept 7-day flying ends


Seven-Day Flying

The instructors for the summer season are Jim Tyler and Don Carey, from Bidford. They’ll be on duty alternating weeks, doubling up when courses require it. Phil Pickett and Martin Greenwood will be sharing the winching.

Mary Benton will be running the kitchen. Opening times will be published in the Clubhouse.

There will be two weeks when we will not be taking bookings for courses. These are the first week in July and the second week in August. There won’t be an AEI evening on the Thursdays of these weeks, to allow for barbecues and the like. There will be instructor cover on these weeks, but the accent will be on solo flying. We hope that daily tasks will be set.


Aircraft News

All the Club aircraft have their CofA’s.

The K18

The K 18 has had its wings re-covered, and wing covers are being made to protect the superb new paintwork, courtesy of Mark and Phil.

The K13s

The instrument panels in the K13s have been rationalised, and they now all have the same layout.

CBW has been fitted with anchor points for ballast weights on the floor. If you need to fly with ballast, please use CCT or CBW rather than using less secure forms of ballast.


Safety Matters

Weak Links

When you attach the cable to the glider, remember to check not only the colour of the link, but also the centre hole. If the centre hole is deformed to an oval, the link is not up to strength and will soon break.

Battered aluminium channels can also bind on the bolt if the slot closes up, rendering the weak link useless.

In both cases, the link needs to be changed, and it should be done during the cable Dl.


The only acceptable way to signal from the launch point to the bus is using a bat. There are two bats, one for each launch line, so there is no excuse. Controllers will only respond to the bat.



Over the winter, the Club’s engineering group have done an enormous amount of work on the ground kit.

We’ve bought a new Land Rover retrieve vehicle, and Old Faithful has been refurbished. The Safari is also serviceable again.

Both winches have received a lot of attention over the winter. The gearbox on Doris has been replaced (several times, in fact, through no fault of our own), as a result of damage caused by the incorrect use of engine oil instead of transmission fluid. Other work carried out includes re-engineering of the drive train on Taffy and improvements to the control systems.


The Site


The generator has been moved to its new housing, and the site electrics have been upgraded. A remote start/stop panel has been fitted in the Clubhouse. Thanks to Barry Monslow and his helpers for this.


The Clubhouse was damaged by a water leak during the very cold weather in January. The water was left on and a pipe in the kitchen burst. It took the better part of a month for the Clubhouse to dry out again.


An area of the field at the West end will be stripped, levelled, and seeded during the spring. This is the start of an ongoing programme that will last several years.

Richard’s Land

There is a region on the South side of the field, between the two hardstanding areas, that we don’t rent from Richard Hobbs. The Northern edge is marked with paving slabs, and the Southern edge is the peri track. This is the area where we usually herd the sheep.

Richard doesn’t mind if we use this area occasionally, for example to land on if really necessary, but we shouldn’t use it otherwise. Aircraft have often been retrieved across this area unnecessarily, and sometimes the cable run has crossed the edge. Please take care to avoid this wherever possible.

Rigging Area

The new rigging area has been levelled and seeded, and the grass is beginning to grow. The area has been fenced off and the old fence will be taken down in due course.

We’ll start to put down anchor points for trailers as soon as the ground has settled.


Club Notices

No Smoking Areas

Please, don’t smoke in the hangars, clubhouse, workshop, or top of the bus. Cigarettes don’t mix well with aircraft, food, or battery acid. Smoking is acceptable everywhere else.

Second Flights for Visitors

Second flights are subject to availability, of course. Often, we don’t even try to sell second flights, especially on busy days, even though they can be a good way to get new Club members.

On Air Experience Evenings, we always try to sell second flights, but availability is much more limited by the onset of darkness.

The cost of a second flight has been increased to £10, but this price can only apply if the flight is taken on the same day.


If you’re first at the field and unlock the main gate, please scramble the padlock afterwards. We suffer from occasional fly-tipping and not giving away the combination might help a little.

Car Insurance

Some important and not very advantageous changes have come to light regarding insurance exclusion clauses concerning “airside” accidents. “Airside” appears to be defined to be any part of any airfield. The situation is quite complex, and you certainly need to check the small print. If in doubt, ask your insurance broker.

This was brought to light by the BMFA, the British Model Flyers Association.

Neil Campbell

Disabled Visitors

We occasionally get disabled visitors who would like to fly with us. The only valid grounds for refusing them a flight is safety, and any other reason is discrimination and therefore illegal. If you have any doubts about safety, talk to the Duty Instructor.

Who’s Done What

Penny Broad went solo on Easter Saturday. On the same day, Peters Jones and Blair landed out in a K13 at high key point, having failed to get back from 1200′. The only damage was an overstressed vario needle where it hit the stop at 12kts of sink.

Pete Fanshawe and Steve Brown now have motor glider instructor ratings.


Flying Fees

We would like to thank some Members who think that computers can reduce our workload in collecting flying fees, payments for T-shirts, telephone, TLVs, courses, and all the rest.

But we still haven’t found a program that will empty cash envelopes, reconcile the sums against the log sheets, and check the details on cheques. This is where Club members can make a difference and reduce our workload. Please:

  • When you use a cash envelope, fill in the log sheet number, flight number, and amount. This even applies to syndicate aircraft.
  • When you pay by cheque, put the same information on the back of the cheque. Check the cheque details.
  • Check that the Log Keeper has filled in the right amount for your flight.
  • If you are one of our few Log Keepers, please remember that somebody has to read the sheets afterwards. Some people seem to think we can read Greek.
  • Please pay on the day you fly. This will save you the embarrassment of being chased around the airfield by the Club debt collectors.

We hope that this doesn’t offend the majority who do all the above. It’s aimed at the minority who don’t, so please help us. Thank you.

Sandra & Roy Wood
Club Bursars


From The Net

100k World Record

Jim Payne, in California, has set a new World Record for a 100k triangle of 217kph. A claim last year of 235kph was rejected by the MC because of a controversial interpretation of the Sporting Code related to the rules governing a finish point which is not the same as the start point. So he went out and did it properly this time.

2l7kph would have got him round the Club triangle in 29 minutes, provided that he could have gained the 14000 ft that he used up in the process.

Air Sports Live On TV

The 1st World Air Games, to be held at 8 sites in Turkey from 12 to 21 September 1997, and embracing the sports of gliding, ballooning, parachuting, aeromodelling, general aviation (air rally flying and long range air race), aerobatics, hang-gliding and paragliding, microlights and helicopters, is already guaranteed to be the largest ever international air sport competition and indeed the biggest of all sporting events world-wide in 1997.

Another important first for the World Air Games will be extensive live international TV coverage. Eurosport has agreed to carry up to 16 hours of transmission from the World Air Games.

The Polish manufacturer of the PW5, PZL Swidnik, has generously offered a brand new World Class Glider as a prize for the World Air Games Gliding Champion. The World Class is a single-design class created by the FIA to bring down the costs of competition soaring. All pilots will fly identical PW5 World Class gliders.

The THK’s brand-new air sports centre at Antalya on the Mediterranean coast will be the site for the World Air Games Aerobatics Championships – both for powered aeroplanes and gliders. This will be the first time ever that world class events for the two categories take place simultaneously at the same site.



As a Club, we have well-defined procedures for dealing with visitors who turn up wishing to fly on Club flying days. There is general agreement that these are as good as we’re going to get without hiring a full-time Club Manager. Nevertheless, they still go wrong occasionally, and when they do, everyone suffers: the visitors feel unhappy, the members on site feel that they’re working when they just want to fly, and the committee suffer from very bent ears.

The way we’ve been handling things for the past two years, and will continue to handle things in 1997, is this. There is a rota of AEI pilots, and there should be two on duty every Thursday, Saturday, and Sunday throughout the year. They have one K13 available for their use for flying visitors, and it is their responsibility to organise the aircraft and the visitors. There is a separate flying list for visitors, kept downstairs on the bus, and the list is closed when there are six people waiting. Any further visitors are told that they may wait for the list to reopen, but that there is no guarantee that they will be able to fly.

This really only applies to busy days, and in any ease, the Duty Instructor can use his common sense to adjust things for the greater good. There is certainly no need to leave aircraft and cables unused just to conform to these rules.

Things go wrong when visitors’ expectations are too high, and this can happen because of things said when they arrive on site, or because of things said on the telephone. Any commitment made by a Club member is made on behalf of the Club, and recently visitors have been loudly insistent that we honour their perception of these commitments, so please be careful what you say and how you say it. (One of the most insistent groups of visitors come from Red Letter Day. They pay much more than we charge, and they often have to travel a long way. Because of this, we’ve decided to end our agreement with Red Letter Day.)

When visitors turn up on site, it’s the responsibility of the Duty AEIs to welcome them and explain things. However, the Duty AEIs are often busy, and we ask all members to welcome visitors. However, please don’t tell them they can fly until you’ve checked the list, and if you’re not sure, ask. On the phone, explain that we can’t take bookings, and if they come along, we’ll do our best but there may be a queue. Please don’t mention second flights or minimum and maximum times, just pass the buck to the AEI pilots.


Speed To Fly

A glider’s polar is a graph of its sink rate through still air against its airspeed, from stall speed to Vne. Here’s an extremely unrealistic polar to illustrate the point, probably from a high-performance T21.
Speed To Fly (STF) is the speed to fly to get from A to B with the least height loss on a day with a particular ‘Average Thermal Strength’ (ATS), and is determined from the polar, thus:

  • Start from the ATS on the Lift axis
  • Draw a tangent to the polar
  • Where it touches, draw a vertical line up to the Speed axis
  • That’s the Speed To Fly

This technique is how the MacCready ring works: you dial in the ATS and the vario indicates the STF. MacCready rings may be calibrated for a particular aircraft, or they may be set up for a typical polar.

Up to a point. These methods give you the Speed To Fly in nil wind, which is an uncommon situation. When there’s a headwind or a tailwind, the polar can still be used to find the STF: instead of starting at ATS on the Lift axis, offset the starting point to the right for a headwind or the left for a tailwind. There’s nothing you can do with the MacCready, though, except to know a few facts.
And what happens in a cross-wind? Even in a 90° cross-wind, where there is no component in the direction that you want to fly, the result isn’t the same as flying in nil wind, because you need to fly further through the air to get to your target. The polar doesn’t give the result directly, because you need a 3-D graph to get the result. The maths gets a little difficult too, because the polar is an experimental graph rather than being a formula.

Here are some real figures, for a Discus. (These figures are taken from an article in Gliding Kiwi).


ATS  Wind  Head  Cross  Tail 
2 0 72
2 10 76 71 68
2 20 82 70 66
4 0 85
4 10 90 84 80
4 20 96 83 77

This table says: if your STF in nil wind with ATS 2kts is 72kts, then in a 10kt wind, your STF will be 77, 71, or 68kts, depending on wind direction. And so on.

If you have a polar for your aircraft, you can use it to get the nil, head-, and tailwind figures, and extrapolate the cross-wind figures from this table: one knot less than the nil-wind figure per ten knots of wind. If you don’t have a polar, or it’s not your aircraft that you’re flying, +5kt per 10kt headwind, -3kt per 10kt tailwind isn’t a bad rule of thumb.

None of this is precise, of course, because ATS is an estimate, normally far too optimistic (most pilots succumb to the temptation to use the Maximum thermal strength), and anyway it depends on the pilot’s skill and the state of his leading edge. However, it should give you an idea of how to adjust the MacCready reading to fit the conditions of the day.

Geoff Butler


The View From The Back


Winter hasn’t been too bad, and at least we’ve flown for more weekends than we could have reasonably expected to.

The field hasn’t been chewed up by the Land Rovers and Tractors, or by gliders landing and ploughing a nice straight(?) furrow in the field. (In past years, we’ve normally had to spend the first hour of post-flying darkness to clean and hose the gliders before packing them in the hangar).

Yep, winter hasn’t been too bad, and now we have the summer to look forward to. There will be more members wanting to fly, more gliders both in the air and waiting to be launched, and more visitors. Especially visitors!!

We all know we need visitors and indeed we welcome them. They provide a much needed. boost to club funds, which brings me to my subject.

Do you know what I really like about Gliding? Unlike individual sports such as golf or tennis, it needs good teamwork (especially on a winch site) to get everyone launched: we do actually help each other. I’ve already discussed the roles needed to get a single glider in the air in the last issue.

Usually there are enough volunteers (I hesitate to say “plenty”) on a flying day to fill these jobs. The reward is your turn to fly at some point in the day. However there are other times when we need the volunteers, but the reward is not so immediate: Air Experience Evenings.

We need teams to man the evenings. This year we are running fewer but larger teams. According to the February issue of S&G there are 125 full flying members in the club. With six teams, each available for one evening a fortnight, we should have twenty people per team. We’ll be lucky to get to get ten! Why??? I know many people work late or work away, but half the club??

Without these evenings, fees will go up, many prospective new members won’t get a chance to try the sport, and those that have decided to join will do so at other clubs. The evenings provide for the present and future of the club in so many ways.

This year we’ll be asking for volunteers to help on these evenings. Please put your name down and be a part of a team, or, maybe, more than one team.

It’s great fun hosting a dozen or more wide eyed, often worried, always excited, visitors. They always enjoy the experience. That’s the reward. We want our visitors to see the club as a team.

Be part of it!


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