The Elipsoid

George Whelan

Just before last Christmas I decided to give myself an early present. Reading through a pile of mags I came across an advert for the Elipsoid, a 2.8 metre span electric sailplane. I had no previous inclination for electric soarers as the ones I had seen were usually small, fragile and overloaded ARTFs that had low performance and crash survivability.

The Elipsoid is a different kettle of fish, sleek, well-made, 2.8m so potentially good soaring performance, and inexpensive at £125 almost-ready-to-fly. I went onto the Internet and tracked one down to Europa Sailplanes in England. A phone call to said company elicited that they had a batch in transit that would be in any week. I duly sent a note and a deposit to secure one. In between Christmas and New Year the package arrived. Perfect timing.

Initial impression of the kit was what a beauty, white glass fuz, wings and tail group in royal blue, a complete hardware kit of bits and a couple of A4 sheets of instructions. I know there are now several of these kits in the club, but I will tell you in some detail how I built mine. The first stage of building was to decide what needed changing. The conclusion was that the battery tray was not in the best location. I re-designed this and incorporated it into the servo tray but in the end actually reverted back to the original! Over the past 5 or 6 years I have gone away from trying to glue or glass fixtures into glass fuz's as one hard landing and flex usually loosens the attachment. I now make all my internal fittings out of 1/4" ply and fix them in using chrome servo screws through the fuz wall. So, 1/ 4" ply servo tray fabricated and two 1/ 4" x 1" lugs glued to the battery tray, I installed all the gear loosely, fitted the wings and tail and put the model onto the C of G balance jig. The instructions indicated what appeared to be a very forward balance point. I decided to move it further back so I juggled the battery and servo's to give me the approximate balance I wanted. I marked up the location of the servo and battery tray and screwed them in with the servo screws.

The tail group is controlled by snakes. These I taped together with masking tape every 3 inches, applied epoxy and lowered them into the fuz down the opposite side to which they exited at the rear. I changed the motor mounting plate (ply in the kit) to one made of PCB as I was going to install a brushless motor and the pre-drilled holes didn't match my motor. This plate was inserted from the inside and was sized so that it fitted 3 mm from the nose. The reason for this was that I wanted a fillet of epoxy and cotton flock on both sides of the mounting plate, it also meant that I could use the hex screws found in computer chassis to mount the motor. I didn't use the wing servo covers provided, I stuck my servos to a couple of Proops mounts with double sided carpet tape and ran in the extension wires. Once everything was in and connected it was time for the big switch on and servo checking. Everything looked fine and the C of G checked again.

So to the field. Model assembled and pre- flight checks carried out, so no more reasons to delay the launch. Norrie Kerr did the dirty deed. Motor on and away she went, a minor trim change and she went up in awesome fashion. After a couple of minutes the bicycle clips were slackened and I began to relax and explore the envelope, as they say. Elevator is quite sensitive so I might dial in some expo next time, aileron response was nice, the Elipsoid is neutrally stable at this C of G, ie it stays where you point it. The transition from power to glide was no problem, just level out and throttle back, no noticeable nose drop.

Time to land. A very long glide but not too fast. Change the battery and up for a second flight. Some good thermals coming through. This glider does not slow down very well. It likes to motor around the sky, which is ideal for thermal hunting. After about 45 minutes I decided to land, again a long flat glide into the grass. I must try and mix in some aileron braking.

I re-launched for another flight. This flight was not great, something was awry, so I made a safe landing and decided to head for home to carry out some checks. I also needed to find out why the motor brake wasn't operating; with the propeller windmilling around in front it was like putting on a brake. Subsequent investigation revealed the 1/8" ply battery backstop had detached, allowing the battery to move back. This has since been replaced with a piece of 10mm square pine.

I have also now removed the snake linkages and installed pull-pull (closed loop) on rudder, and, via a bellcrank, to the elevator. This gives a more positive control response. Over the next couple of flying sessions I am going to spend some time optimising the trim as I am sure this model can soar with the best. You get real glider performance without all the launching hardware you need to cart around.

This model in terms of bang per buck is definitely eleven out of ten!