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Model gliders - 2 metre span electric powered glider
The 2 metre span electric powered motor glider. This aircraft has done many hours of flying and here can be seen undergoing some maintainence work.
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Orange solarfilm is being used to re-cover the glider, replacing the original fibafilm.
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This model glider which is my own design came about as a requirement for an easily launched thermal soarer which didn't require the use of an elastic bungee or winch for launching from flat flying fields.
The glider uses all built up balsa construction and was built to a suitable size and weight to make use of cheap 540 type electric motors and 7.2v model car battery packs.
The fuselarge uses 1/4" balsa in a standard box construction with ply doublers at the front. The main wing is a conventional balsawood rib and spar construction with sheet balsa at the leading edge as per the picture. Tail surfaces are sheet balsa with lightening holes cut in.
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The front end during re-covering shows the ply doublers and the 540 electric motor mounted in the nose.
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Partially covered fuselarge on the model glider shows the 1/4 inch square balsa framework and the control runs.
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The model glider uses three channels of radio control operating the rudder, elevator and motor controls. A closed loop system is used for rudder control using control line wire, elevator control is achieved by the use of a plastic push rod cable (snake). Finally the motor uses an electronic proportional speed controller. No ailerons are fitted to the glider, the wing has sufficient dihedal incorporated to give roll stability and rudder authority.
These pictures show a recent rebuild and re-covering where I modified the aircraft slightly. The glider originally was covered in fibafilm which after several years of service had slackened in places, warps had also began to creep into the wing. In an attempt to improve matters the old covering was removed and balsa diagonals fitted to the wing to hopefully brace out the warps.
The model was then covered once again, this time using solarfilm.
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The wing on the building board being fitted with some diagonal braces. These are being added in an attempt to remove a warp and also increase the rigidity of the wing.
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The model glider after the modifications and re-covering in solarfilm have been competed.
The aircraft now sports a wireless video camera on the canopy, ready for some video picture experiments.
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Under power the glider can climb at a reasonable rate under full power, a good altitude for gliding to commence can be achieved in two or three minutes climbing. Once at height powering off the motor allows the prop to fold up and it's thermal hunting time.
The gliding performance of the model is very good, height loss while searching for an updraft is slow and forward speed can be kept low. Once in a good thermal the model can soon gain height very quickly to the point when it is getting quite a challenge to spot. It's very important not to loose sight of model under these conditions as you may never regain eyebal contact.
Sometimes it's more important to loose a strong thermal than find one if you want to keep your model glider.
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Model glider page two
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