A model airplane still should look like a real aeroplane! So, after a while, we let ourselves to be attracted by a model with a "fleshy" fuselage.

Extana looks like a cross between an Extra and a Katana, thence its somewhat exotic name.

The roomy fuselage allows for use of any type of battery available. Also the five-cell LiFePO4 2300mAh will fit inside easily. As the wing is detachable, in two pieces, also the transport brings no problems. 

The model has a pleasant flying behaviour, low minimum speed and sufficient excess of power for 3D aerobatic figures. Due to the nimbleness and controllability and low landing speed it is still suitable for the backyard flying. The hand launching is easy and the model handles easily also a landing into a taller unmown grass.

The design allows for testing and operating the taileron function, i.e. direct lift control by changing of the wing camber, using ailerons deflecting together in the same sense and mixing this feature with the elevator deflection in the opposite sense.

What you need

RC set

• Transmitter             minimum of four channels

• Servos  3*                            e.g. HS 81 (17 g) rudder + ailerons

• Servos  2*                            e.g. HS 65HB (11 g) elevator

• Receiver                              e.g. Rex 7 (20 g)

• Split cables                         2 x elevator, 2 x ailerons, 1x rudder, 1x controller

• Motor                                    AC 135-180 g

• Controller                            AC, min. 40 A current (JETI Spin 44)

• Propeller                              e.g. APC E 12/6 - 14/6,5

• Accumulators                    LiPol, LiFePO₄, 2300-3700mAh, (260-400 g)

A list of further necessary material: epoxy glue, medium thick cyanoacrylate glue (well proven is the Flash brand), connectors to accumulators.

A list of necessary tools: modelling knife, soldering pistol, nippers...

EXTANA - Weight analysis

The practically tested powerplants/propulsion units;

the units are listed in a decreasing order of suitability.

1. Motor PJS 1900, 1038 RPM/1V, mass 132 g

   Controller                              JETI Spin 44

   Propeller                               APC E 12/6,5

   Accumulators                       4 x LiFePO₄ 2300 mAh /30C A123 Systems

   Advantage : one set of accumulators suffices.

    

2. Motor PJS 1900, 1038 RPM/1V, mass 132 g

   Controller                  JETI Spin 44

   Propeller                               APC E 13/6,5

   Accumulators                       3 x LiPol 3700 mAh /20C Shark Power (PQ)

   Advantage: longest duration of flight.

    

3. Motor PJS 1500, 765 RPM/1V, mass 132 g

   Controller                  JETI Spin 44

   Propeller                               APC E 13/6,5

   Accumulators                       5 x LiFePO₄ 2300 mAh /30C A123 Systems

    

4. Motor PJS 1500, 765 RPM/1V, mass 132 g

   Controller                  Jeti Spin 44

   Propeller                               APC E 13/6,5

   Accumulators                       4 x LiPol 2500 mAh /20C Shark Power (PQ)

How much energy do various sets of accumulators have?

To power a model it is possible to use various sets of accumulator of various capacities, but with a different voltage. The decision what propulsion to choose is not always a completely rational one. Usually our decision-making is influenced by our actual ownership of some part of the propulsion, charging, price etc.

In a table it is clearly shown how some set can supply most power. In the real life also the gross mass of the model (mass of a certain accumulator set) plays a role, as does the real quality of the accumulators. It gives us a general idea, however. 

 From this aspect the LiFePO₄ batteries do not look like a winner, yet the practical experience puts them into the first place. The shorter duration of flight is compensated by the speed of charging and the possibility to operate with only one set of accumulators.

List of parts in the kit :

• 2 x wing half of EPP

• 2 x wing spar (carbon tube of 10/8 x 500 mm dimensions)

• 1 x wing joiner (dural tube)

• 2 x securing hook

• 2 x securing rubber loop

• 2 x wing spar plugs of EPP

• 2 x wing pin 5x80mm

• 1 x fuselage of EPP

• 1 x fuselage belly (forward part)

• 1 x undercarriage support of plywood

• 1 x motor bearer of glassfibre

• 1 x tail skid of EPP(in two parts)

• 1 x tail skid stiffener/support

• 1x undercarriage spring

• 2 x wheel

• 1 x securing tube for the undercarriage wheels or 2 x Quicklock

• 1 x accumulator tray holder (plywood with a small hole)

• 1 x accumulator tray (plywood rectangle)

• 1 x accumulator tray (plywood with a hole)

• 3 x wooden strip of 3x10 mm (accumulator tray)

• 1 x screw

• 1 x elevator of EPP (pair)

• 1 x vertical stabiliser of EPP

• 1 x elevator stiffener, carbon 1 mm/1000 mm

• 1 x vertical stabiliser stiffener, carbon 1mm/ 500mm

• 11 x movable surface hinges

• 4 x plastic control horn (ailerons, elevator)

• 1 x glassfibre rudder horn

• 1 x rudder control rod

• 2 x fork (rudder)

• 4 x control rod, 1mm diameter (ailerons, elevator)

• 1 x securing tube for control rods

• 1 x cockpit canopy

• 2 x canopy holder (glassfibre)

• 2 x canopy holder (plywood)

• 2 x canopy screw