The design of the e-Go Single Seater
The e-Go stems from Giotto’s desire to design a canard aeroplane with efficient aerodynamics, great visibility and offering the pilot a very safe and enjoyable flying experience.
A key design consideration from the outset has been for the aircraft to operate efficiently and get good performance from modest engine power. The large mainplane offers good low speed handling and achieves the 35kn minimum handling speed, required for an aircraft to be approved as a microlight in many countries, without the need for flaps which can be complicated in a canard design.
The following are a few of the characteristics designed into the e-Go.
Firstly on the performance side, the nose down pitching moment increases with speed, the aircraft rests increasingly on the canard wing of higher aspect ratio and the mainwing is unloaded. Thus at speed, the aircraft flies on the higher aspect ratio front wing while load on the main wing is kept to a minimum and the efficiency is improved. In the cruise at 90kn the canard is providing around 70% while close to the stall the front wing is relatively unloaded with around 30% of the lift.
Fins turn the planform of the main wing into a more efficient higher aspect ratio equivalent one while also providing some fwd force (thrust) in flight due to the direction of the lift acting on them hence helping reduce the overall wing drag.
The result is that the e-Go achieves a similar cruise speed to many of the fastest conventional aeroplanes using the same power and half the wing area (although these are often either stuck with higher stall speeds or require the extra complexity of powerful flaps).
And the larger overall wing area provides a generally more benign aeroplane.
Also, while canard aeroplanes with high wing loadings generally require high coefficients of lift on the front wing which may bring problems with contamination such as insects, the lower wing loading of the e-Go allows a much less sensitive aerofoil with the added safety benefits. Low wing loading is generally considered to give a rough ride in turbulence but somehow (I won’t argue the laws of nature) the e-Go manages to stay pretty comfortable to the pilot.
Another attribute of the e-Go’s aerodynamics is that the aircraft has a remarkable rate of role. The ailerons are very effective and nicely weighted. Despite the size of the mainplane the aircraft can be snap rolled well and this has been a feature really enjoyed by the test pilots from the outset. The canard also tends to lift the nose around a corner rather than having a tailplane push the back out of a corner. This result can be felt in the form of responsive handling and that aircraft can regularly perform a full 360deg turn in around 7 seconds. In these manoeuvres the decreased canard angle of attack in the pull-up keeps you safely away from stalling it too.
The pilot’s impression has been one of the key points to go with the aerodynamics and performance.
So, besides the outstanding visibility which was one of the main drivers to the aircraft’s layout, the CG is set right in the chest of the pilot who is therefore at the centre of the action and clear visual cues are built into the configuration of the aeroplane so, as the instrument panel rises to hide the horizon in level flight, the pilot is made aware that the canard is about to stall. At the other end of the range, the sound of the wind is clearly audible above the engine noise to witness higher speeds. To allow the pilot full appreciation of the flying experience, the aircraft instrumentation, while as comprehensive as MFD units can be, only includes a couple of buttons!
The e-Go is made almost entirely of carbon composite materials. This results in a very stiff, strong construction but at very low weight. The carbon is made up of layers of material and these layers are sometime separated by thin foam cores that help provide rigidity. In areas needing significant strength, such as the longerons and wing spars, many layers of carbon might be used, up to 20 layers, but in other places we can be down to a single layer. Again, by using what is appropriate at each location weight can be kept to a minimum. The whole fuselage shell, as it comes from the mould, weighs in at just 6.3kg. Some of the flying surfaces additionally have an inner core of lightweight foam. The foam is often hollowed out to save more weight. This approach is often more associated with wet, inside out, layup construction but for the e-Go there are moulds that are used to form the outer skins and the moulds are again used after the foam cores are installed so that the whole wing is compressed into shape and then oven cured. The low distributed aerodynamic loads also allow these low density materials to contribute structurally to the aircraft’s airframe.
The overall shape of the fuselage as well as that of the longerons, the seat and instrument panel support arch add to the protection of the pilot providing elements that are forced to crumple by their shape and absorb energy during impact.