Pike Prestige 2PK F5J model 1350g Normal version

Prestige 2PK Normal version F5J Electric glider - RTF weight 1350g – 1480g, stiffness of the spar – 50%

Sold and backed up by the Exclusive Samba AU agent since 2002

The basic model is supplied with the complete servo wiring loom, wing, tail and fuselage protective bags, linkages and quick links for all surfaces.

Colours can be specially ordered according to the scheme and colours shown. Fluoro colours cost extra.

Talk to our sales team.

Optional Extras

• Fluoro colours + $50

• Non standard colour scheme + POA

• Ballast Set + $79.99

• 8 degree wing joiner (1) + $29.99

• IDS Set to suit flap/aileron installation (1) + $25

• IDS servo installation at factory (1) includes frame and labour (no servo incl) + $100

• Servo installation into fuselage (2) no servo incl + $79.99

• Model can be ordered with a 30mm nose cone at no extra cost

• The factory can supply and install servos at competitive prices

First of all thanks to our good friend Philip Kolb for designing an exceptional model in the F5J world. He was not influenced by various fads in the F5J scene and used all his knowledge, experience and the best available software to construct the amazing PIKE PRESTIGE 2PK.
To this we added the full rohacell core to the design, the whole model is made in heated aluminium moulds to a very high temperature. This technology creates a light, strong and stable platform that will provide years of flying.

It is worth mentioning a few properties we have found very nice after flying this model for a while.

Circling

In circling the model as expected did not have a need for extreme dihedral joiners since the aerodynamic design and airfoil changes does that work in a better way than increasing dihedral. It was first produced with 6-degree tip joiners and then we added an 8-degree alternative. It has also been flown a lot with 6-degree joiners with good success in low altitude thermalling at EC F3J 2019. There should be no need for extreme joiners though this is again a personal preference.

Circling camber can be extreme (5-8 degrees) while still maintaining speed because of a new tail design that keeps the energy better (less drag). This means a high bank angle is possible and yet you can still keep the high lift in a tight thermal.

The large and newly designed rudder makes it possible to yank the model into any thermal you find.

Penetration

As you will find described in the designer Philip Kolb’s writeup the penetration in all camber settings is very good because of the new tail design. Now you can change the camber at any point without losing flying energy as we see with many other airfoils. The model now just speeds up to the desired speed/camber setting and keeps that for a trip over the whole airfield through lift and sink. Night and early morning testing have shown sink values as good as 0,35-0,4m/s in distance mode (1mm up along the whole trailing edge and measured by altimeter). That means search mode for thermals is very efficient and provides a fantastic glide ratio. Flying in full camber in the same conditions gives sink values in the range of 0,25-0,3m/s but less area is covered.

Landing

Landing the Prestige 2PK is easier than ever. No aileron setup is needed (aileron goes to neutral when brakes applied). Only flaps with elevator compensation. Still, the model slows down to a crawl and pushing over is easy as the new elevator keeps the energy well even with full flaps applied. The rudder is also better and bigger and with the new high dihedral middle and aerodynamic airfoil changes, it corresponds well to rudder input and is not as much affected by sidewind as earlier models. Though it should be said that the lightest layup has very light tips and heavier tips (inertia) might be preferred if the landing area has lots of sidewind and/or turbulence.

The nose is removable. It is made longer than needed and can be shortened ( max. 100 mm) according to engine weight and lipo. Install equipment and shorten nose to fit preferred CG. The original nose has a diameter of 32 mm. It is designed to fit cheap and reliable outrunners for lighter versions. We also produce a nose cone with a slimmer diameter of 30 mm to suit smaller, slimmer motors.
The servos and receiver are located in the fuselage under the centre wing panel therefore there is enough space in the front for the motor, controller and lipo. Battery size from very small and up to 2300mah can be used as much care was taken to design a very thin but almost square fuse in the front area.

The complete wire harness is pre-built into the centre panel and the central connector plug is pre-installed. The wire harness for the fuselage is also delivered ready-made.

Servo compartments in the wing are laminated on all sides with carbon fabric, so a very strong box has been created in which the IDS system from servorahmen.de can be mounted. We recommend installing IDS for KST X10 mini, JRDS 181 or 189, Mks 6130 for flaps and MKS 6110HV in the tips. For the fuselage, suitable servos sized like MKS 6110 HV work well.

Some words from designer Philip Kolb

Fundamentals of the  design:

Since there is no towing in F5J, the structural challenge is significantly less than in F3J and the design parameters quite obviously are different. There is no need to design a light, stiff and strong spar. This by itself lowers the structural weight of the glider. As well the wings don’t need to be as thick as on an F3J glider out of the same reason – there is no need for a very strong spar to take the occurring high g-loads. In line with this, low flying weights and the resulting low Reynolds numbers call for the use of very thin airfoils.

Nevertheless, an F5J glider due to the rule set can be exposed to flying conditions from absolutely calm air to wind speeds up to 12m/s. For being competitive even in high wind conditions there is a definite need to be able to vary the wing loading of the glider no matter how sophisticated the aerodynamic design of the glider is.

Therefore great care was taken to optimize the design of PRESTIGE-2PK to perform over the whole range of possible flying conditions. Great emphasis was put on the fact that PRESTIGE-2PK actually can handle a lot of ballast very well. To achieve this goal the airfoils of the wing - even as they are very thin – need to be able to provide a high maximum lift coefficient. To achieve this goal a high (but not super high) aspect ratio wing showed the best results, leaving sufficiently wide chords to optimize the airfoils for both, the low speed (low wing loading) case as well as the high speed (high wing loading) case. In the end, the Aspect ratio came out to be 19.2 at 3.9m wingspan. To reduce induced drag with this fixed span the planform was optimized to be as elliptical as reasonably possible. It thereby features a relatively high taper ratio (this measure even helps to lower the weight and inertia in the outboard area of the wing and thereby achieve better manoeuvrability), which in return was counteracted by using a considerable amount of washout twist in the outboard wing panel to achieve docile stall characteristics and a minimal turn radius for thermalling.

Airfoil explanations:

Like with any modern model glider-design the wing features optimized airfoils along its span, taking the local Reynolds numbers into account. For the PRESTIGE-2PK 7 different airfoils were developed and optimized along the span. One criterion was to determine the optimal flap chord. On the one hand, substantial laminar flow which should not be tripped by the hinge line or the gap between wing and flap should be achieved. On the other hand, positive flap deflections should result in minimal curvature change on the upper side of the wing when cambering up the airfoil. The former calls for relatively narrow flap chords and definitely has advantages when flying at higher speeds while the latter shows advantages when putting more emphasis on very low flying speeds.

In the end, 28% flap chord reflected a very wide optimum solution for PRESTIGE-2PK. The wing-planform thereby was developed to maintain the 28% chord depth of the flaps and ailerons all along the span.

To enhance performance, modern airfoils used at low Reynolds numbers (like on almost all F3K, F3J and F5J aircraft) feature a so-called “kink”, which means, that the lower side and the upper side of the airfoil are not continuous and smooth at the same time. This allows for a wider envelope of flap angles to be used - especially positive flap angles to camber up the airfoil - because this measure results in a less steep and abrupt pressure recovery on the aft upper side of the airfoil.

Due to the unstable boundary layer conditions at low Reynolds numbers this steep and abrupt pressure recovery on the aft part of the airfoils upper side can cause significantly higher drag as a result of large laminar separation bubbles and thereby a loss of performance especially when circling slow at steep bank angles – which is mandatory in F5J!

For the PRESTIGE-2PK the kink in the airfoils is developed like follows:

The wing airfoils have no continuous smooth surface on the bottom and top at the same time. When the lower surface is clean, the wing is in a configuration optimized for low lift coefficients, thus for fast-flying (i.e. fast cruise when heading towards a thermal through the sink or under motor power when climbing at the same time is not desired). After using 2 degrees of camber flap out of this configuration, the upper side of the airfoils is continuous and smooth.

The tail configuration of the PRESTIGE-2PK is a derivative of the original PRESTIGE. The sizing of the tails and the development of the tail airfoils were undertaken by following aspects of docile handling and reducing drag at the same time. Six non-symmetrical airfoils were developed along the half span of the horizontal tailplane and similar to the wings’ airfoils were optimized according to the local Reynolds numbers at each spanwise position. The airfoils for the horizontal tailplane are in fact slightly different from the ones used on the first PRESTIGE. Now that stabilizer and elevator are built in solid core technology (on the PRESTIGE the stabilizer part was still built in hollow moulded technique), the airfoils on the horizontal tailplane could get thinner considering the very low Reynolds numbers and to save weight on the rear part of the fuselage to keep the inertia as low as possible.

To achieve very precise pitch control a hinged elevator was chosen, but as an F5J-planes’ elevator is pulled up very often, a relatively wide elevator chord was used. This kind of combines the positive aspects of an all-moving horizontal tailplane and a hinged elevator – low drag on the one hand side, precise control on the other. As mentioned, the elevator of an F5J-plane sees major up deflections while pulling tight thermal turns, therefore the airfoils for the horizontal tailplane were specially designed to produce low drag for exactly this configuration. The customer just needs to understand, that for this elevator tailplane very precise high-resolution servos and a slop free linkage are mandatory to reach the actual precision this elevator can deliver.

Different from the horizontal tailplane, the vertical tailplane needs to deliver substantial lift force to counteract and damp sideslip motions. The sizing of the vertical tailplane as well as the sections therefore primarily were chosen to achieve very good yaw damping. Thereby the symmetrical airfoils of the vertical tailplane cannot be extremely thin in order to still provide large maximum lift coefficients. The thickness of the seven vertical tailplane airfoils thereby varies from 7% to 5.3%. They are very similar to the ones used on the first PRESTIGE as there was not much room for further optimization.

All in all, I really do hope that the new PRESTIGE-2PK will perform well for you in F5J and make lots of F5J pilots happy with its performance and handling qualities. It should meet its design purposes to be a worthy successor of the PRESTIGE, as this is still the nicest plane to fly I’ve ever flown.