Design 
Jerzy Krawczyk, in addition to Ekolot’s Junior and Topaz, has several light aircraft, cropspray, and sailplane designs to his credit. In creating the Elf he has employed composite sandwich and carbon structures to achieve the exceptional strength and durability required to pass UK BCAR Section ‘S’ airworthiness certification.
The Elf meets all of our original design criteria, is a delight to fly, and possesses exceptional soaring capabilities.
Engine
Our prototype used
the JPX 330 engine which, unfortunately, was withdrawn from production
in 2006 after over 20 years in the market. Fortunately, Compact Radial
Engines in Canada has produced a very similar unit for us. This is
20% more powerful than the JPX and also employs a clutch which
eliminates folding prop ‘chatter’ on start-up and allows the prop to
fold whilst the engine is on idle.
This engine has displayed excellent, instant re-start capability and has run faultlessly in duration testing.
Control
The Elf employs full span flapperons, and airbrakes, and has excellent rudder/stick co-ordination. The NN17-18 aerofoil possesses mild stall characteristics and overall, the handling conveys a strong sense of stability and security to the pilot.
Specification and Performance
Special Note: Engine-on performance figures shown are as tested on our prototype with JPX engine and 116cms prop.
Production aircraft will have the more powerful Compact Radial engine and a 126cms prop for which we project a climb rate of 500 ft/min.
Engine off, the Elf with it’s 120 ft/min sink rate is capable of slowing down to exploit the slightest lift and core the smallest thermal. This is where the fun and skill challenge begins and where, if the pilot falls out of lift into sink, he can be confident of a quick engine restart and climb back to the area of lift.
Specification
|
Weight: |
145 kg (with BRS) |
|
Gross Weight: |
260 kg |
|
Area: |
10.8 sq/m |
|
Span: |
11.2 m |
|
Length: |
5.7m |
|
Aerofoil: |
NN18-17, mild, stable stall unaffected by rain or insects |
|
Engine: |
24 hp ‘Boxer’ |
|
Prop: |
1.26m, folding |
|
Fuel Capacity: |
15 litres |
|
Proof Load |
+6 : -3 |
|
Pilot Limits |
Height 1.9m (6’3”) |
|
|
Weight 100kg (220lbs) |
Performance
(Flight Tested with JPX Engine)
|
Cruise: |
50 mph at 5,100rpm |
|
Max Climb: |
400ft/min at 30mph* |
|
Stall: |
27mph |
|
Best L/D: |
26.4:1, 150ft/min at 45mph |
|
Min Sink: |
120ft/min at 39 mph |
|
Airbrake: |
300ft/min at 45mph (13:1) |
|
Fuel: |
4.5 litres/hour |
|
Note: |
We reserve the right to change specification and performance details without notice. |
*Estimated at 500ft/min with Compact Radial engine.
U/C Option A (Grass
Operation)
(click to enlarge)
U/C Option B (Grass
and Tarmac Operation)
(click to enlarge)
Transport and
Assembly
The Elf can be transported in its custom trailer and is a two-man 15-20 mins assembly. Controls are self-locking and each wing has two mainspar, and one rear spar pin. Tailplane attachment is by two bolts and a control horn bolt and nut.
A special tool is supplied for pin extraction during disassembly.
Operation
If unloaded from a trailer, the Elf requires two-man assembly. If hangered, the Elf is a one-man arrive-and-fly aircraft which can be taxied out to take-off.
Important: The Elf is offered in two undercarriage configurations.
a) Narrow, twin wheels with nose wheel and no brakes, as on our prototype for grass strip operation.
b) Carbon spring axle, wheel brakes, tail-dragger. For grass or tarmac strip.
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