XBow²

Pure flying wing!
Its 1.2m (47") span easily allows for transportation ready to fly
Extremely robust with multi-layer full carbon construction and lack of fuselage
Quick and cost effective build with only 2 servos

Conceptual design

The original concept of the Bow goes all the way back to the year 2014. The goal has been  to design the most simple flying wing with high lift capabilities for dynamic flight performance on less than ideal slopes. From 2019 on, several teams have build multiple prototypes out of different mould sets and tested those in all kinds of conditions. In 2020, we finally consolidated all the experiences and feedback into the completely redesigned XBow².

Uwe Heuer redeveloped the set of airfoils based on Peter Wicks latest Airfoil design with the following set of requirements: 

Further increased flight dynamics and higher terminal velocity

Predictable stall behaviour in all stages of flight

Maintaining the good thermal flight performance and broad flight envelope

CAD

The aerodynamic specifications have been translated into an aircraft design using "engineering best practice":

  • All airfoils are aerodynamically smoothed
  • The single piece wing allows for easy transport ready to fly
  • A very compact design reduces cost for manufacturing and logistics and allows for a very reasonable retail price
  • Tail boom and tail are plugged into each other and secured by tape. By this design, risk for damaged from hard landings is greatly reduced
  • Optimized tail geometry for less drag and minimized heading deviation
  • Perfectly straight hingeline minimizes servo forces
  • All openings for servos, RC install and battery are large enough for easy access

Layup

Wing and tail are manufactured for daily use in all conditions. The lack of fuselage requires weight in the front to balance the CG anyways, so we rather invest in strong laminate than in dead weight. Leading edge and D-Box are strongly reinforced with carbon and aramid and mostly survive even  "tree landings" without damage.
Load distribution points to the tail boom are also reinforced to make the easy-to-replace tail boom carbon tube the weakest link. 
We are not doing epoxy gap seals on the flaps to to weight reasons, but you may do tape seals if you wish (like in F3K). 

Slope

Created with Sketch.
  • ~750g take off weight
  • For light to strong slope soaring conditions 
  • Bungee starts (up to 200m!) and thermal flying in good conditions if you are lacking slopes
  • Carbon-Aramid hardshell in D-box, up to 5 layers in the center, 2 layers in the tips
  • Rear part of the wing made of carbon sandwich construction  (160g/m² Carbon, 1mm Airex, 50g/m² Glass)
  • Extra carbon reinforcement patches for highly stressed areas


ST Light

Created with Sketch.

Light layup (available soon):

  • ~600g take off weight
  • For light and moderate conditions on the slope
  • Bungee start for thermal flights if you are lacking slopes
  • 80g/m² Carbon Spread Tow, 1mm Airex, 50g/m² Glass
  • D-box, Nose and openings reinforced with 160g/m² Carbon


Tail

Created with Sketch.

The tail in ST Light and Slope version is equally laminated very light in 60g/m² Carbon Spread Tow, 1mm Airex, 50g/m² Glass. 
In DS version, we are using 160g/m² as outer layer and added reinforcements.


Graphics

Our models are manufactured in high-end clear carbon construction. Graphics are cut from Oracal 751 high performance cast foils and applied wet to the surfaces. You can choose from a big variety of colour combinations, replace the decals if damaged and even change the colors later on.  We can also apply Oracal 6510 neon colours for increased visibility. However, we only recommend them for secondary colour due to higher thickness and weight. Additionally, we recommend using different colours top and bottom. 
The individual pilots name may also be applied. Don't hesitate to ask for help when chosing the colours. We may provide you with real photos of your individual color combination if you are unsure. 

Prices and lead times

Created with Sketch.

updated 13. June 2020

Due to the high demand at start of production, the lead time is currectly approx. 7 months.
Please contact us to get on the pre-order list (non-binding and free of charge).
We will contact you prior to your production slot to confirm your order.

Prices (incl. 19% VAT)

Slope: 

449€


ST Light:

499€


Protective bags for wings and tail:
59€

Shipping fee excluded, will be calculated depending on destination



Scope of delivery

Created with Sketch.
  • Wings and tail in selected layup. Flaps prepared and working
  • Decals applied in selected colour scheme (2 colours each, top and bottom)
  • Carbon tube materials for tail boom interface
  • Tail boom made from 10/9mm carbon tube
  • Spare tail boom
  • CNC cut carbon flap horns
  • Covers for RC-hatches, laminated from molds



Recommended equipment

Created with Sketch.

Especially with flying wings, strong servos without any slop in gears or linkages are a must. This RC equipment proved to be working perfectly:

2x KST X10 mini in servo frames with counter bearings
Standard receiver with max. 10mm thickness, long antennas recommended
2s Lipo with approx. 800-1600mAh (from around 10mm thickness, you may need to split and unfold the battery)

Build and Settings

Created with Sketch.

Full build documentation pending

Center of Gravity: 
89mm from leading edge center point
Precicely balanced, model upside down and levelled

Slope/Thermal phase: 
Flaps 0.7mm up
Travel, measured on inside edge:
Aileron: 9mm up / 6mm down
Elevator:  5mm  up / 3mm down
30% expo

Speed:

Flaps 0.5mm up
Travel, measured on inside edge:
Aileron: 9mm up / 6mm down
Elevator:  5mm  up / 3mm down
30% 

DS:
Flaps 0.5mm up
Travel, measured on inside edge:
Aileron: 7mm up / 4mm down
Elevator:  4mm  up / 2.5mm down
30% expo


Please use the contact form for any inquiries. We will come back to you within a day.

Pictures and videos of XBow²

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Build instructions

The complete build instructions is work in progress and will be updated on a regular basis. Please download always the latest version by clicking the link below.