Wizard of Oz (oz8472)

About this Plan

Wizard of Oz. Simple 4 foot glider for radio controlled slope soaring.

Quote: "James H Osborne describes his experiences with Wizard of Oz. A 4 foot simple glider for radio controlled soaring.

THERE are many areas in the British Isles highly suitable for the sport of slope soaring - and sport it is. We in Yorkshire are particularly favoured. The steep, heather-sprung Cleveland Hills offer slopes facing in every direction and they are deserted except for the kestrel hawks and jackdaws. The moors are excellent for the week end family picnics and we choose our sites according to wind direction and we can always fly as there is always a breeze on these hill tops.

On the slopes no one can complain of the noise or nuisance - no noise, no nuisance and no spectators except the sheep and kestrels - and they disappear the moment we put a glider up. We find the gamekeepers most friendly and very interested in our hobby.

Slope soaring is the ideal way to learn to fly a radio model - steady, stable flying for, minutes on end - no engine trouble, and for the expert, aerobatics are real fun - just imagine looping a glider and completing the manoeuvre fifty feet below your position - then climbing steadily upwards for two or three hundred feet.

Bruce and I have enjoyed this sport and relaxation for four years now and we have been fairly successful in interesting other modellers. Unfortunately many power R/C flyers seem to think that there is no challenge. They usually appear when conditions are ideal and throw their power models off the edge. These machines usually climb in the strong lift but are treacherous to handle and inevitably they crash - (no dihedral and not enough rudder movement). The disgruntled power men then stalk off muttering that there is nothing to slope soaring as 'anything' appears to soar.

The slope soarer is a highly specialised machine and requires an experienced pilot to put up a reasonable performance. The models we see flying fall into one of these three categories - they are usually any old power model, or scale types, or functional models for the man who likes flying and lots of it. Our models are in this latter class. Recently I have noticed a number of continental kit models and these combine good performance with semi-scale appearance. My criticism of these machines is that they are either light breeze types or gale force types - they are not versatile enough.

Requirements: In our views a slope soarer should not exceed four feet in span for single channel control. Larger models tend to be difficult to build, expensive, difficult to repair, difficult to transport and often heavy due to wing strengthening and centre joining methods and devices. I close the case against the large model by pointing out that a small model will turn tighter and needs less height for recovery after manoeuvring.

A glider must be very strong and simple to operate. Radio should be one of the small single channel relayless types operating on a 4-1/2 volt torch battery and using an Elmic Conquest escapement - 'bang-bang' control is a must.

The final requirement is that the model must be extremely stable and able to soar over a wide range of conditions ie from a very light breeze to near gale. This last need is extremely difficult to fulfil as most models seem to have their own rather restricted speed range and hence can only be flown successfully on a few days during the year.

The Wizard of Oz is a model specifically designed to meet with the above specification. The model is strong, four foot span, has a sheeted fuselage, sheeted leading edges and large enough compartments for any of the popular receivers and actuators. With a 44 volt torch battery, Terrytone, and Conquest actuator the weight is around 1-1/2 to 1-3/4 lbs giving a loading of 10 to 11 oz per square foot.

The model is quite orthodox but we have not yet considered stability and performance. Stability is taken care of by adequate dihedral angle and balanced side areas to give smooth turns. A preservation of at least 2° longitudinal dihedral angle ensures stability in this plane... "

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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