11-Dec-18 - 04:26 PM

Thermal Circle Text - Thermal Circle 02

Written by Hayden Daley - 13 September, 2007.

Due to long term illness I was hospitalised again, so the soaring circle has missed an issue. In this edition we will take a look at RC programming for competition sailplanes and their uses and some general information that will make the new comer to the competition scene enjoy the events more readily. I will also cover two different ways to create working water ballast for scale sailplanes. There is also two competition reports, the first is the Victorian State Championships and the second the L.S.F Tournament held at Jerilderie.

Programming for Competiton Sailplanes

Not all functions discussed will be available in every RC system however the functions covered can be found in the Futaba FC28, Multiplex 3030 and Profi 4000 , JR/Graupner MC18, MC20,MC22,MX22,and MC24. These systems all provide excellent programming options to fine tune and trim your sailplane for the best performance in the competiton environment. There are certainly other radios with glider functions but these high end systems are all excellent in the options they allow and through adjustability, get the best performance from you sailplane.

I cannot give exact details on how every radio is programmed so this is a broad over view of flight phase programmming and general programming for competition sailplanes, f3b, and this information also relates to straight thermal sailplanes.

There are three tasks in F3b, distance, thermal and speed, so three different settings will be required for optimum performance. To allow for these different settings three model memories will be required. When naming the model memories I use the model name with the designations of d, s ,t to indicate the model memory for each task with "d" standing for distance etc. Flight phases by there very name indicate different flying stages or different stages of flight. In all of these systems flight phases can be assigned to switches and they allow different settings to be switched in the program, in essence they are switchable phases that allow for the launch, reflex and task settings and landing settings to be activated without programming. The flight phase programming allows for landing settings to be set to the throttle and switched between during flight without physically programming. Launch, reflex and landing flight phases allow for all the differential settings, the trim of the model and offsets the raising and lowering of surfaces to be adjusted. Flight phases can also be assigned to the throttle stick to allow for adjustments to the landing settings. It is not uncommon for three phases to be assigned to the throttle for the landing task. Treat flight phases as a model memory within a model memory.

It is important when you begin your setup that all the servos are plugged into the correct position on the receiver. The most critical of these is the plugging in of the flaps and ailerons. With the MC24 Aileron must be plugged into the Aileron slot, the second aileron plugged into the gear slot or channel 5, and flaps plugged into channel 6 and 7. Without this the MC24 will not function the correct servos and it is impossible to have the correct adjustments. Other systems may be different, the Multiplex systems allow for servo assignment. But common to all of these systems is that If the servo is plugged into the wrong position assigned or not, the programming does not function correctly.

When programming your radio you will have to allocate flight phases before they will work. This is done through phase assignment. For example, if you wanted to have a two stage launch setting you would have to allocate two launch phases to your three position switch and the final switch position would be for normal flight. You will then have three fully adjustable settings activated and fully adjustable through your flight phase settings. This will allow you to set the first launch setting, flaps down etc, assigned to your switch, you can now launch and as you get further up the winch line you can then switch to your second stage or second phase and activate the different settings. Finally at the end of your launch switch to the normal flight phase or to your other task settings as required. When landing you will have the ability to set different down elevator, aileron differential, aileron to rudder mix as you apply crow braking. This will dramitically aid in hitting the spot during the landing task in different weather conditions through the trimming that can be provided through adjustment.

I know that the MC18 and MC 20 also have switchable model memories. In these particular radios you can set all your launch settings and others and then be able to switch model memories if weather conditions changed or adjustments were wrong. It was also an excellent way to run comparisons of different launch settings, speed settings, distance and thermal settings.

I have mentioned the function differential, this is the setting that allows for less down aileron when compared to the other aileron. One travels further up than the other goes down less. In this setting you are trying to make you sailplane turn in the most efficient manner. This is one of the most critical settings you will make in the setting up of your competition or other sailplane. I have found through experience that around 70% differential is a good place to start on most sailplanes. This will not be perfect but through experimentation you will acheive this most efficient turn. Adjustments to differential will also require changes to the aileron to rudder mix and with full span aileron to flap, all the surfaces working as aileron, that more rudder will probably needed.

If your model has a V-tail it is worth setting your travel adjust to 50%, this prevents over travel when full elevator and rudder are applied. With this setting you can only travel your servo 100% of its travel. When this is not set it is very easy to reach the mechanical limits of the pushrod system in your sailplane and cause damage to links both on the V-tail linkages and with the linkages at the front of the model. This setting does not apply to models without a V-tail.

Rudder to Aileron mix is another critical setting. It stops your model adverse yawing or side slipping whilst turning, again reducing efficiency. Aim to have the mix keep the turn with a little yaw as possible. This again will take time to find the optimum setting and remember when setting, the travel limitation on the servos and the mechanical problems that occur.

Differential is also used within the launch setting, to allow for the use of aileron in the launch stage. The best setting here is to have aileron differential set at 100% and to have aileron 1, flap 1 and flap 2 set to launch setting down and then to have the turning surface, the aileron controlling the model up the line with 100% differential, this surface then travels upwards only during the launch. This dumps less line tension during launch and provides excellent contollability.

Using reflex during launch will also require a phase assigned and to be switchable both on and off. Reflex aids most sailplanes during the “ping” or “zoom” at the end of the launch and it also helps your sailplane return from downwind by reducing drag. With this setting experimenting is again the best way to find the optimum setting, but 2 millimetres upward at the trailing edge is a good all round setting.

All computer radios have functions that are not used on every model that is flown, but if through programming you can improve the performance of you sailplane I believe it is worth experimenting to acheive this. You may find that different launch flap angles provide for a better launch or that during your landings more or less down elevator eases your approach to the spot. Making adjustments and experimenting is they only way to acheive the best performance from your sailplane.

Preparing for Competiton

This is an explanation of some of the things that long term competition pilots will already know, however this information will be helpful to the new comer.

It is important that you arrive at least an hour before the event begins. This will allow you to set up your winch, test models and to stop rushing around with little time, setting up models and other equipment. To do your best you must be relaxed and focussed and if you are not organised this will effect the way your score in the event. Everybody gets pre competition jitters, but these will reduce markedly as you fly in more events and gain expereince. There is nothing worse than models or equipment failing and affecting your place in the event. Also be ready for your heat. The contest director will assign each pilot into a heat for each round. This allows people to fly against other opponents and allows for frequency clashes. You should check the draw and be ready with your model, winch and key in the board for the start of the heat. Competion’s run more smoothly when this occurs.

It is best when wiring the servos in your sailplane that you use custom wiring when connecting servos. Soldered joins are hard to change in the event of a stripped servo and promote black wire corrosion when soldered. Custom wiring allows for the normal servo plugs to be used with your wing servos.

When shopping for servos for your sailplane, you should shop by kilograms of torque provided by the servos. 3.0 Kg torque with metal gears would for me, be the very minimum. As prices go up so does the KG of torque! It is false economy to put in low strength servos into a competition sailplane as there is nothing worse then going up the line with high tension and having a servo strip and the surface deflect or lock in place and end in a spiral or crash. The subsequent loss of control is not only dangerous but also expensive. Good servos will last a long time and are worth investing in, for the longevity of your model in windy weather.

This debate is endless but I consider for the increase in torque that it provides, if your servos can handle 5 cells it is worth gaining the “free” torque that this provides. You may have to charge at the field but the backup if a cell drops is important and for this alone I will always run 5 cells. I also believe that you should carry the largest battery pack possible within weight and balance considerations. High tension launches put incredible strain on servos and during launch the current draw is massive especially with digital servos. An 1100 Mah pack is a good size but will probably need charging after 5 rounds or so.

Competition flyers will often have many different winch lines, as they use different lines for different weather conditions. Lines are graded by poundage and by line diameter. Light lines generally used in light weather are around the 1.1 millimetre 175-225 lb range. In heavier conditions anything up 1.4 to 1.5 millimetre 250 lb line is used. Light lines are delicate and the really light lines are easily damaged and become unreliable and break eventually because of this. If you wish to launch alot, for example in practice, heavier lines would be more appropriate as they are more resillient and less delicate and provide many more launches per line than light line, so are the best value. However light lines have less line drag so launches are generally higher with lighter line, the line bows less during the launch and stretches more. When storing line or the night before competition you should soak your winch line in water. This cause the line to strech more and become more resillient during launch. Your line will launch better and last longer if you soak in water.

Large parachutes have a bad habit of taking of tailplanes if you over rotate at the top of the launch. If you have a large parachute it is worth trimming them down with scissors or buying a smaller parachute. They are also more reliable in windy weather, large parachutes also have a bad habit of exploding in windy weather with high tension.

Carbon fibre is reknowned for causing radio problems and has caused many costly crashes. If you do a range check and find that you have low range and glitches with your radio, carbon fibre in your sailplane may be causing this to occur. The first fix is to run dual conversion FM or PCM receivers. PCM will also help, but dual conversion will generally fix the problem. However, I had a Graphite sailplane that had a kevlar and carbon fibre fuselage that cased me many problems and the cure this time was to change to 40 Mhz. This was expensive and was a last resort but consider this if you have major hassles with this problem.

You will need to purchase two clocks, one that counts upwards for your flight duration and another for working time that counts backwards. Your clocks are important not only for competion work but are also helpful in practice. It is worthwhile timing all of your flights as this shows improvement in technique with an actual figure, the flight time.

Having your own “Spot” to practice spot landing is also a useful tool for improving your landings. A correctly made spot graduated in metres will allow you to make every landing that you make, a practice spot landing.

The Lomcevak Logger is a height logging device made in the Czech Republic. It is distributed in Australia by Model Flight in Adelaide. This is a minature presure sensitive height logger that down loads approximately 10 flights to a computer and plots launch heights, climb and descend as they occur during flight. When you download to computer the logger presents your flights as a graph allowing comparisons and is especially useful when setting launch flap as you can compare launch heights. The logger comes with a lead and software for PC based computers and is supurb for setting up new models. This device will allow you to optimise your sailplanes.

Some pilots that fly thermal competition will have two models with which they compete. The weather conditions dictate which model they use. They will use a lighter f3j type model, a graphite or similar in winds up to ten knots or so, and heavier f3b type model often with ballast in heavier wind conditions. This can provide an advantage as these lightly loaded models are easier to launch in light weather and hang around longer in these weather conditions. In opposite when the wind blows these lightly loaded models cannot handle the wind as well as a ballasted f3b type sailplane. Choose as to what the weather conditions are most like where you fly.

You must make sure that all surface on your model are fitted with linkages that are free of slop and that move with as little friction as possible. Friction cause excessive current drain and reduces torque, while slop can lead to surface flutter during your flight.

Your equipment must be legal. Winches have strict load limit based on current draw and batteries have a size limit. If your equipment is illegal you can be diqualified.

If you do not have the lathe skills and machinery to build a legal winch there is an Australian company that can build one for you. The name of this company is Airstrike and it can be found at www.airstrike.com.au. These winches are powerful, well made and used by alot of competition pilots for these reasons.

You must be a member of a club and have current insurance to fly in competition, without this you will not be allowed to fly. The M.A.A.A has insurance cover that covers all approved flying sites. If you have an accident without insurance, imagine the liability claim for causing serious injury or death with your model.

In the beggining you do not need moulded models to compete. You can fly in events known as R.E.S or rudder, elevator and spoiler competitions, which definitely means you will not need a moulded model. Although if you attend a few contests there are always models for sale and often at very good prices. It is also worth talking to pilots at competitions in regard to what sailplanes perform the best, if you intend buying a new moulded model. There is often different layups available, more carbon, glass wings, light weight versions etc. So use these events as a chance to gain knowledge before you buy.

Model Flight in Adelaide sell a moulded a model called the Neon Plus Mk 2, that is made in the Czech Republic. It has a wing span is 3.4 metres and the wing section is an old thermal classic the Selig Donovan 7037. This thermal model is supurb value for the begginner and I highly reccommend it, if you are a begginner, and what a cheap, well made moulded model. It is approximately half the price of all other aircraft in its class and size.

Another option when shopping for model sailplanes is to buy second hand sailplanes, and there is web site dedicated to this, so check out the Aussie RC Trading Page run by David Jones from the L.S.F. This is a web site where many sailplanes, radios and other secondhand equipment is listed with contact points to the seller of the item. It can be found at www.ozemail.com.au/~majali. This is free service, so feel free to advertise if you have equipment to sell!

The Southern Soaring League in South Australia and the R.C.G.A and V.A.R.M.S in Victoria as well as other clubs in other states hold regular competitions throughout the year. Check the internet for event details and call or email the clubs to find exact event locations and starting times.

Water Ballast for Scale Sailplanes

There is nothing more impressive in scale soaring than when a large scale sailplanes enter the circuit and dump a load of water. It adds realism and is not that difficult to add to most models.

The first way of acheiving this is with Rhom retract equipment. You will need a fuel tank, pressure cylinder, hose line and Rhom sevo operated valve and brass tubing. Fill the tank with water, connect up the lines and pressurise the pressure cylinder with the pump. When you are ready to dump water open the servo operated valve, the system pressurises and forces water from the tanks and out the lines to the brass tubing either out the sides of the fusealge or through the wings with a bend in the tubing and exiting through the root. There a couple of engineering issues here though that need to be addressed. Cable tie everything that has line this will prevent the system from failing and apply tape around the tank this will stop pressure deforming the tank and use tank clunks.

The second way of acheiving this is through the use of smoke pumps as used in aerobatic aircraft for making smoke. You will need two of these pumps, a fuel tank, hoses and brass tubing for the exit points. Use two clunks in the tank and choose the size of the tank you wish to carry in your model. Using the two pumps connect one to each clunk line and the route through to your brass tubing, in the position where you wish the water to dump. This method is by far the easiest to acheive as these smoke pumps have built in actuators which plug into your receiver and are easily set up on a switch for acctuation.

Both these methods work well, look good in flight, and provide a working way to help your scale sailplane penetrate better in heavier wind conditions. But be careful not to add to much weight, water is heavy!

Competition Report’s

The Victorian State Championship and Jereilderie Tournament reports come from Rod Watkins the president of the R.C.G.A. The Victoria state thermal glider championships were organised by the RCGA and run at the VARMS club field in Wantirna Vic on 21 March 04. This was once again a very successful event with an entry list of 17 competitors but unfortunately no visitors from interstate. The event was advertised as a two day event in the hope of attracting interest from interstate pilots but due to a lack of response, the event was reduced to one day.

The conditions were perfect with classic autumn light early morning lift making way to strong mid day lift followed by difficult conditions in the late afternoon. The event was flow with eight rounds and one drop score which placed the emphasis on consistent flying through out the day.

The final placings were decided in the last round of the day which caused many upsets. Former Jerilderie (double) champion Mark Doyle was caught out with a double line break and hence flight attempt from a low launch height. Mark’s attempt to get away from chasing a thermal downwind ended in disaster with a meeting between his Caracho and a low flying tree and a resultant badly damaged model. Not nice to see at any time.

The event was won by one of our up and coming young flyers, Theo Arvanitakis, flying his Ellipse 4 and Estrella with great skill through out the day. I think this event was Theo’s first victory in the RCGA league and surely not the last. Long time RCGA competitor, Graham Norman came in second by only the slimmest of margins, 3 points out of 7000, so congratulations to Graham too.

Click here to view the results...



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