Dialling in the reflex

Reflex added to the wing in the form of a 10mm up elevator mechanical trim setting 

Following the troubles I had with my maiden flight, Ted suggested that instead of changing the trust angle or the CoG that I should add some reflex to the wing ...... I said do what?!

Apparently all flying wings inherently want to tumble AoT because the CoP is behind the CoG. In order to stop this from happening you need to add an extra downward moment to the wing in order to get it to fly level, ie just what the tail section of a standard config airframe would do. If the aircraft designer has done his job well then this will already be part of the aerofoil, however as is the case with most models this does not happen and it's up to the pilot to add mechanical up trim.

So I grabbed to ruler and the allen key, loosened the control horn and adjusted the elevators so that they both had 10mm of up trim as their neutral position.

The plan now is to fly the Skywalker X5 and see how much electronic trim is required to get it to fly stable and then from there we'll adjust the mechanical trim again.

We will sort this out on the next flight along with developing a solid launching technique, I can't expect Stu to be available to launch her for me every time I want to go for a fly. :)

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Skywalker X5 first test flight

The big first launch

The build was finished and I'd done a few static tests at home, now it was time for the real deal. Testing grounds are a large public open space reserve in Woodbridge. Conditions where great, 7am, 12km/hr wind from SE. We had Cam as the cameraman and Stu as the launcher.



Basic setup

I was quite anxious about this launch as on the forums a lot of Skywalker X5 users had complained about troubles with 'torque roll' on take-off. Also (on the forums) a lot of users had complained about stability issues and the poor flight characteristics of this airframe.

We completed two glide tests (no power) and she flew great. Stu and I discussed the torque roll issue prior to take-off and decided a half throttle launch would give us the best chance of limiting any adverse roll. We also decided that if she didn't have enough thrust to take-off on half throttle that I'd kill the power, glide her down and then we'd start again. I've had too many wing overs on take-off with other airframes to risk it on this one.

Well, I'm not sure if the guys on the forums got it wrong or I just got it right because she took off with stacks of authority, dead straight and no signs of a torque roll. :)



The boys before the flight

Whilst I had her balanced correctly (to the 260mm CoG point) she still felt a little nose heavy, needed constant up elevator to stay level. However she was very slick in the air and flew really quite fast (for me anyway) even on 2/3 throttle. I was very nervous flying her as she would quickly fly to the edges of visual range. Despite being nervous we managed to have 2 successful launches and test flights, landings were fast but on an acute angle so the airframe handled them very well.

Overall I don't think I could have asked for a better maiden test flight. Thanks to Cam and Stu for their help and guidance on the day. I also need to thank Ted for his guidance with the build and sorting out the twisted elevon.  

Before next flight I'd like to try balancing her with a more rearward CoG and she how she handles then. Also with the full white colour scheme I found it hard to tell her orientation in the air, especially with her moving so fast. So I'll paint the winglets to see if that helps.

Maiden launch of the Skywalker X5

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Skywalker X5 - Phase 1 build and setup

The finished product - Skywalker X5 fully built

Overall it was a straightforward build, no major surprises. I think the finish on the EPO foam is ok but not as good as other models I've had. I am however a massive fan of the wing design, the Skywalker X5 has some real curves and looks more like aircraft than the flat wings that dominate this category.

Here is a list of the specs;

ESC: Turnigy 40amp Plush
Motor: Turnigy Aerodrive D2826/10 1400KV
Prop: Master Airscrew 7x4
RC Rx: ORX 6 ch 2.4 Ghz
Servo: 2 x Hextronic HXT 500
Battery: 2 x Turnigy 2200mAh 25-35c 3S
Wing area: approx. 22dm2 (0.22m2)
AUW: 970g

I've installed component just as the manufacturer has suggested, 2 x 2200 maH batteries in the front compartment, the camera will be mounted into the middle compartment and the Rx and autopilot will go in the rear compartment.



The main trouble I had was that elevons was quite twisted (and the hinge was ripped) during shipping I assume. I contacted Ted and he suggested pouring boiling water over it and then massage/straighten it up. This worked well and it wasn't long till the elevon was around 95% fixed.


Double adapter




For now I have only mounted the Rx in the rear compartment, however I have placed some coins in there as ballast to represent the APM. That way I can do initial testing with close to the planned AUW. I have also placed coins as ballast for the uBlox GPS.


The Rx and coins to act as ballast for the APM




I think one of the best features of the Skywalker X5 is the way that the hatch is fixed to the airframe. Double screws that screw into plywood bulkheads, creates a very, very strong fixing and helps to provide rigidity to the fuselage. The only thing I am concerned about is the screws (they are small) and when I un-screw the hatch in the field that I'll loose them in the long grass! So I hot glued a couple of plastic drinking straws into the screw holes. Now I can still get my screwdriver in however the screws can't fall out.

Straw glued into the screw hole to stop screw falling out in the field

I had a look at the foam hinges and was not really impressed so decided to create tape hinges but sticking vinyl tape on both sides of the elevons. I've been really impressed with how this system works and can see that it's infinitely more robust than foam or even plastic hinges.

The stock recess for the ESC is in a great location, I just love how Xen Skywalker have designed this, however it wasn't deep enough to have a flush finish. So I pulled out the trusty modelling knife and made a deeper recess. I plan to create an ESC cover in future that has air vents for better ventilation but for now the ESC is simply covered by a piece of vinyl tape.


Tape used for wing hinge

Coins on motor mount for uBlox

Deeper recess












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