Some of our club members are also keen fliers of slope soaring gliders and we thought it could be of use to prospective new members and to our fellow club members to describe the hill sites in North Herts and East Beds that we use regularly in the hope that a few others might be tempted to have a go.

Hours of endless fun are to be had with any reasonable model glider, out on the hillside enjoying the excellent scenic views, the natural quiet surroundings and the free exercise walking to and from the sites. Slope flying is a very relaxing activity with no fuel or power packs to lug around, no motor starting problems and no messy model at the end of the session, unless you are unfortunate to land it in a fresh cow pat! Slope flying can be quite challenging and just as rewarding as flying a powered model. Careful use must be made of the prevailing wind conditions and any thermal activity to optimise the model performance. Aerobatics present a particular challenge as opening the throttle in an attempt to regain the height lost in manoeuvres will be found to be very ineffective!

The slight drawback of slope soaring is that it not only depends on the wind being of suitable velocity as in all model flying, but in addition it can only be indulged in if the wind direction is up the slope of one of the available hills. Us electric flyers find that slope soaring fits in well with our electric activities because when the wind is too strong for our lighter electric models it is sometimes ideal for slope flying. It also helps if you are retired or can get off work easily as suitable days for slope flying do not always occur on weekends! To give an idea of how often slope flying opportunities arise, a few years back when flying slope soaring gliders was our only model flying activity, we were averaging some 50 to 60 slope flying sessions per year. Now when the wind is light we fly electric models even though conditions might be right for slope flying, so that over recent years we have only averaged around 20 to 30 slope flying sessions per year.

SLOPE SOARING SITES
Slope soaring uses the upwards component of the wind velocity as the air blows up the slope of the hill to counter gravity and keep the glider airborne.The hills in this area are fairly modest affairs and so the model must be reasonably efficient aerodynamically, so forget the draggy airframes with high wing loadings. All the sites we fly from are on farmed land and livestock can sometimes be present, so do not forget to shut all gates that you open and leave no litter etc. Also no powered models of any kind, ( i.e. IC or electric ) can be flown on these hills and proof of insurance should be carried although we have never been asked to produce it.

The hill sites we normally use in the Herts/Beds area are Deacon Hill south of the B655 near Pegsdon village, Sharpenhoe Clappers above Sharpenhoe village near Barton-le-Clay, and Warden Hill east of the A6 road at north Luton. We have also flown from the Barton Hills near Barton-le-clay, but Deacon produces much better lift in the same weather conditions. We have yet to try Ivinghoe Beacon near Ivinghoe village beyond Dunstable.

The three sites we normally fly are each usable in different wind directions, and together cover the wind directions from just E of NE to just S of W, with very little overlap between sites, as detailed below:

Sharpenhoe Clappers: Principally NE winds, but usable in winds from approx. 23deg to 67deg. The car park is off the road between Sharpenhoe village and Streatly, at the top of the hill.The hill forms a long ridge which usually produces some strong lift even when the wind is light. The flying site is reached by walking along the path from the car park along side the wood, across the top of the hill in the direction of Barton village and finally passing through an iron gate onto the hillside overlooking Barton. To land your model you may sometimes have to pass back through the gate and land on the pasture on the hill top. There are usually a few walkers around so take care when landing. This site is managed by the National Trust. This is the only site we fly from that requires no hill climbing!

Deacon Hill: Principally N to NW winds, but usable in winds from approx. 293deg to 30deg. It is advisable to park your car in Pegsdon village near the Live and Let Live pub and not in the Icknield Way car park on the B655 as break-ins occur frequently at the latter car park. Access to the hill from the village is gained by going through the pub car park, walking along the B655 towards Barton for a hundred yards or so, then crossing the road and through a wooden gate into the meadow. You should then turn left, back on yourself, walking in the field alongside the B655 towards Hitchin. After passing through two more wooden gates turn sharp right and follow the hedge towards the bottom of the hill. Pass over a stile, turn sharp left and walk to the hill and up it to the top. By the time you reach the top you will realise just how unfit you are and you should make a mental note to do this walk a lot more frequently! Deacon is an excellent hill in NW winds. The lift is usually good and there are acres of flat hill top on which to land. The north facing slope is shorter, more uneven and the landings are more difficult. In a N wind it pays to walk back past the Trig Point and land on the open hill top. Walkers pass right through the launch points so again be careful when landing. Also there are sometimes grazing animals around. This is a very scenic site and is managed by a nature conservancy group.

Warden Hill: Principally W winds, but usable in winds from approx. 255deg to 295deg. Driving down the A6 from the direction of Barton towards Luton, immediately after entering the built up area of north Luton negotiate two roundabouts staying on the A6. Immediately after the second roundabout turn left up Warden Hill Road. Drive to the top of the road and turn left, parking on a gravel carpark outside some school gates and opposite some bungalows. Then walk along the path towards right hand end of the hill as you look at it. At the bottom of the hill pass through a gate and climb up to the top of the hill. You can fly from there but if the wind is dead on the hill it pays to turn north along the hilltop path towards Barton for about one hundred and fifty yards or so, through some bushes to a clearer area just before the Trig Point. Warden Hill probably produces the least lift of the sites we fly, but it forms a long ridge and is perfectly flyable. In stronger wind strengths the level of turbulence becomes noticable, but it is not too bad in wind strengths up to around 20 mph. The landings are a little restricted. You can land along the path on the hilltop, or walk back through the bushes and land on the open ground on the hill top. In an emergency you can land in the field behind you. Again there are usually a few walkers about. This site is managed by Luton Town Council.

In certain wind conditions other slopes of these hills can be flown but the flying is much more difficult and restrictive. More often than not there will be no other model fliers present on the above hills so frequency problems do not usually arise. If another flier should turn up then do not forget to check what frequency they want to fly on as soon as they appear as no peg frequency controls are operated. On a few occasions on Sharpenhoe Clappers there have been paragliders present. If they are there you must chat to them to ensure there is no conflict over airspace. We have flown with them several times and had no problems with them at all. They usually stick to the more northern end of the ridge near what they call the bowl and we keep out of their way down the more southern end. Should one of them wander into your airspace you must manoeuvre your model to keep it well out of their way or even land your model. You are unlikely to meet paragliders on the other hills.

The following comments relate to our experiences from flying the above hills and should not be taken as being applicable to all hills in the U.K.! Some hills in the U.K. are much higher/steeper/wider than our local hills and much larger/draggier/ heavier models may be flown.

WIND SPEEDS
Usable wind speeds for slope flying on the above hills are generally in the range 7 to 20mph, although in the right conditions and with a suitable model you can fly in winds as low as 3 or 4mph, or as high as 25mph. Even higher wind speeds can be flown but it becomes increasingly difficult and the enjoyment factor falls off rapidly.

SUITABLE MODELS
Because gliders are devoid of propulsion systems they provide the simplest and cheapest form of RC model flying. When there is sufficient lift the flight can last as long as the Rx and Tx batteries provide power. The slope gliders we normally fly have wing spans between 1.5 and 2m, and are of the sport aerobatic type. It is also possible to fly scale or semi-scale models of powered aircraft (without power of course), which are referred to as PSS models. Although very low wing loadings of say 6 or 7ozs/sq.ft. can be flown in light wind conditions, as the wind velocity increases the wing loading must also increase in order for the model to penetrate. For general flying a wing loading in the region of say 10 to 12ozs/sq.ft. is recommended, but a loading as high as 16oz/sq.ft. can be quite satisfactory on the right model even in the lighter wind strengths. Low aerodynamic drag also aides penetration and improves the efficiency of the model. A highly cambered wing section may produce good soaring ability in lighter winds but it restricts the speed range of the model and does not provide versatility in a slope soarer. As with powered models the aerobatic ability of the model is improved with a semi-symmetrical wing section or even a fully symmetrical section, although the latter may make retaining altitude difficult in lighter wind strengths Slope models generally should be robustly constructed. There is no point in light construction as ballast will have to be added to obtain a wing loading that will provide a useful penetrating ability. The additional weight might as well be employed in the structure to produce a stronger model. Hill sites are often rugged in nature and landings can sometimes be rough, particularly if the model lands on the sloping face of the hill. As in all types of model flying it is useful if the model comes apart in the event of a heavy landing to reduce damage. Construction using nylon wing bolts, frangible ply plates or rubber banded flying surfaces all help in this regard.

Thermal gliders can of course be flown from the slopes and provide good soaring performance. However they are not particularly robust, and not normally very aerobatic. For those who are not too sure of their slope flying skills, Phoenix make a range of EPP models that are hard to break. The Synergy Duet Sport and the Ban-SHE are typical slope aerobatic trainers. Many other manufacturers produce some very good ARTF models, although the fully moulded models become very expensive. If any of you still build your own models then spruce spars with sheeted wings and plywood sided fuselages are the order of the day. It is useful if your model is able to accommodate extra ballast in order to help penetration on windier days. Some of the more modern transmitters provide for air brakes which are very useful when landing a glider in a tight space.

DRESS CODE
No you do not have to wear a tie when slope soaring but you do have to wrap up warm. Standing on the top of a hill in a 15 to 20 mph wind in the cooler months of the year is not for the faint hearted, but the discomfort can be largely offset by suitable clothing. Even in the summer it is usually necessary to wear extra clothing on the hills. Think in terms of wearing an extra couple of layers on top of what you would need at our site in Letchworth. As the outer layer in the cooler weather we usually wear water proof trousers and jacket which keeps the wind out and keeps you dry if you do get caught out by the rain. Remember there is no shelter and no handy car to dive into! A warm hat, scarf and gloves are also required in the colder weather. It is beneficial to wear stout shoes or walking boots at all times of the year as the ground can be rough. At least the amount of equipment you need for hill flying is only a fraction of what you take to the Letchworth field to fly powered models, which is just as well as you have to carry it up the hill! We carry a small haversack containing our transmitter, a few odds and ends, and a flask of coffee. A mobile phone can also be useful, not only for possible emergencies, but also for ringing the wife to tell her that you will be an hour longer than you told her because you are having such a good time.

We hope that this article has been of some interest to both those who have already done some slope flying but not in this area, and those who have not tried slope soaring but think they would like to have a go. We can provide training for slope flying should your skills be limited, using the buddy lead system. We even have an old model or two that you can have a go on should you be interested to see what it is all about. Although controlling a model on the slope is much the same as flat field flying, the atmosphere on the slope is totally different. There is no throttle to open to make the model climb, instead you often have to work hard to gain height using whatever the elements present you with. With a glider things happen more slowly than with a power model and this leads to a more relaxing flying experience. Do not go away with the impression that slope soaring is boring however because it can be quite challenging especially when you start introducing aerobatic manoeuvres.

So if you are interested in having a go at slope soaring, or even flying a flat field glider (powered or otherwise), go to the club flying field and make contact with an experienced member. They will refer you to one of our experienced glider flyers who can then advise you on how best to proceed, before you part with any cash on equipment that may not be suitable.

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