Flow infopage


FW5 flow
Competition model


FW5 flow
Wingspan [mm]:
1 500
Weight [g]:
from 255
Zone 52-21

After an intensive period of development, we present the successor model of our tried and tested series of Fireworks:

FLOW 5 is largely a new construction. Not only the long version of the name was changed, we also have integrated several novelties concerning materials, method of construction and aerodynamic design.

Numerous prototypes, more than 1000 test launches and many tireless helpers (special thanks to Robert Mayer) were necessary, before we
were satisfied with the overall concept.

Characteristics in brief:

Maximum performance and at the same time good handling were the most important facts for the design of the wing.

We chose Zone 52-21 as airfoil. It convinces in all sections of the flight, such as launch, speed and thermal.

The fuselage is very short, which results in excellent thermalling characteristics. The masses are concentrated in the middle of the glider to enable highest starts.

For more technical information read our building instruction (pdf-file 1,1MB)

Novelties for 2012:

Some time has passed since the development of FW5. We have gained much experience with the model, we could enjoy its strong points, but also explore potential for improvement. We have therefore carried on developing the model and added three additional versions to the range, especially designed for competition use. The three versions differ in terms of stiffness and weight, each version is optimized for use in a specific weather situation.


All the versions have the following improvements:

- stronger and stiffer spars
The fw5 has a large dihedral which is flattened during the rotation of the launch. Because of that strong throwers can hear a slight noise after releasing the plane. The strong spar avoids this flattening, which will increase the starting height.
- stiffer ailerons

- The boom is now 3 times stiffer against bending forces and also stiffer against torsion forces. The weight stays the same.
- Every version is delivered with a different fuselage length. These lengths fit exactly to each mass distribution of the different wings.
By that oscillating during the start can be minimized.

Vertical stab:
- The vertical tail is now free of momentum during the launch.
- It is stronger against breaking due to the new core material rohacell.

Horizontal stab:
- Is now stronger against breaking due to the new core material rohacell.

Take-off weight app. 265g Take-off weight app. 275g Take-off weight app. 285g

This light version has a carbon wing made of 39g/m2 IMS carbon fabric. This version combines excellent weight, high stiffness and durability for everyday flying.

for the medium wing we use 70g/m² IMS Spread Tow for the D-box and spread 55g/m² fabric for the ailerons.
Due to the carbon strengthened ailerons we could increase starting heights significantly compared with the normal version.

Bastian Jütte could reach the first place in the Austrian Championships 2011 with this version.
The full-spread-tow-wing is also made of 70g/m² IMS Spread Tow, which enables a good weight and very high stiffness.


Novelties October 2010:

Due to the experiences during the last season we still could optimize some details of FW5. Following changes will be integrated in series production from now:

There is more carbon in the spar. We now use UMS-rovings for this.
---> The wing gets stiffer. This is important especially for starting the glider with disc-launch.
The ailerons will no longer be elastic flaps. They are cut and mounted with adhesive tape. There is an extra layer of glass on the hinge line.
---> Die position of the hinge line is exactly defined, the ailerons are stiffer
We have new throwing pegs, which are designed ergonomically. (standard-version)
---> No pain in your fingers even after many launches.
On the bottom we changed the design to crossbeams.
---> better visibility

We use UMS-rovings in the boom.
---> The fuselage is stiffer, especially for lateral load, as you have it during the start.

The elevator has carbon reinforcements and a longer carbon joiner.
---> improved strength even for strong throwers

These improvements have cost app. 5-10g more weight. Thanks to the good initial weight the FW5 stays even though one of the lightest in his class.

Evolution of the model:

The new FW5 "FloW": When we started developing a new F3K-model, a lot of people told us about their experiences and successful improvements. Our problem was, that we could not get any evidence that these changes really brought a progress. So we tried to prove all of this with test flights. First of all we had to find a good testing method to get serious data. After several trials we chose a comparing method with a dlg that is started at the same time from a rubber. So we had starts with constant energy, which made it possible to judge the atmospheric disturbances as wind and thermals. The solutions of our test you will find in the magazine "Aufwind" and on our homepage.

The factors for a high start which we proved were (Performance such as L/D and minimum sink rate were calculated.):
- centered masses
- little masses
- little/high dihedral
- narrow wing tips
- little/high sweep back
- different aspect ratios
- different airfoils: HM51, AG foils, Zone foils, and mixes and strakes of these
- asymmetrical stabs
- stabs with higher aspect ratio
- different starting methods: steep or flat
- shorter boom

After about 1000 test starts we realized the most important points to start high:

- centering masses to keep the radius of gyration low
- little flying masses
- the priority of these two points: centered masses are more effective than little masses.
- The pilot has to start in different ways when the wind varies. This makes also a big difference.

The construction of the fuselage is a special novelty. It is produced as sandwich construction over the whole fuselage with airex und balsa as supporting material. This high effort in development and production is rewarded with fantastic weights of nearly 35g and simultaneously high stiffness.
The materials we used are:
- kevlar in the front for 2.4ghz receivers
- IM spread tow in the back for good stiffness
- airex sandwich in the front and balsa sandwich in the back for good strength
The fuselage is shorter in the back and the front to center the masses. Thermalling characteristics, especially agility and sensitiveness for tharmals have clearly improved by this. You can easily stay in the thermal by making small steering movements or change the turning direction with nearly loosing no height.
Nose made of kevlar for installation of 2,4GHz.
CNC-milled radio board with access from the side for tidy mounting and quick changing of servos
One-piece fuselage built with IM spread tow
Pre-fabricated threads for fixing the wing
The end of the boom is shaped for easy mounting of the rudder.
- Airfoil: Zone airfoils from 52-21. These airfoils are very suitable for high start and far distance flights.
- Wing geometry:
- Area: 22,4dm²
- Aspect ratio: 10
We chose again a more wide wing tip like the fw4 has. We made tests with narrow wing tips to reduce mass at the tip. The result was bad during flight and also the strength of the tip decreased extremely. So we had to add more material to reach enough strength. That means in the end we had more weight and worse flying performance. So we chose again the wide tip that circles great and forgives mistakes. Now you can dare to thermal very low and near to obstacles. This sensitive feeling for thermals is also supported by centering masses.
- Wing materials:
The D-Box is made of IM spread tow. We used more material in the middle of the wing to withstand the higher torsion forces and to center the masses. As the flying weight was near 250g, we could afford to integrate additional material. Further reduction of weight is not senseful, as the ideal conditions for a model like this (no wind, soft thermals) are very rare.
We used rohacell as supporting material to provide a smoother surface.
When searching the ideal place for the servos we first tried wing servos. As we needed some lead in the nose of the fuselage with this arrangement, the flying weight was 13g higher and also the distribution of the masses was worse. For this reason we came back to situating all servos inside the fuselage.
For joining of the ailerons there are levers to be hooked in on the downside of the fuselage. The servos are located in the fuselage.
Optimized distribution of the masses in the construction: More carbon spread-tow in the middle of the wing, the tubes in the ailerons are carbon at the inner side and glass on the outside of the wing. (wing of standard-version)
There are 4 colours for the wing to choose from: red, orange, green, blue
The colour assistent will help you to see how the painting will look like on the glider.

After all tests we finally returned back to our well-established FW4.2 stabs, as we had the best results with these tails. In addition, these stabs are very popular amongst our customers in the meantime. The reasons for this are probably the good functionality, low weight and the easy way of installing it.

The CFR-stabs are made out of moulds using carbon fleece. (standard-version)
The CFR-stabs are nearly completely pre-fabricated.
The mechanism inside the rudder for controlling the elevator is ready installed.
Easy installation as the boom is pre-shaped for mounting the rudder.
The elevator is dismountable.
ACCESSORIES (not enclosed in kit)  
We also offer completion of the kit for this model.
4 pieces of GP NiMH Accu 35AAAH are ideal for the power supply.
Protection bags for the wing

  • Shell construction, with airex and balsa as supporting material and carbon as outer skin. We used among other things IM-carbon (for stiffness in the boom) and kevlar (for installation of 2,4GHz).
  • Shell made of rohacell as supporting material and glass fabric or IM-carbon fabric as outer skin
  • Spar booms made of carbon / shear web made of balsa planked with glass
  • Shell made of balsa-sandwich with carbon fleece (standard version), core of rohacell with an outer skin made of glass fabric and carbon rovings (competition version)



  • Ailerons are cut and mounted with adhesive tape
  • Gap sealing of ailerons with adhesive
  • Screw mounting for wing is pre-fabricated
  • Openings in fuselage are cut, fitting of rudder is pre-fabricated
  • Kitparts (radio board, pushrods, levers, ballast etc.) are included in kit
  • GFR-stabs completely prefabricated apart from mounting the lever for rudder
  • The building instruction can be downloaded from the website.

Flow infopage