Yet another Skywalker build

[electricmick]

Just started putting it together so I thought I would document it so others can learn from my mistakes as usual.

The shopping list:

Skywalker 163cm wingspan FPV foamy: http://www.bevrc.com/skywalker-168cm-epo-airplane-version-iilimit-time-offer-p-17.html

Motor: TGY AerodriveXp SK Series 35-36 910Kv / 310w  http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7074

ESC: Mystery 40A Brushless Speed Controller (Blue Series) http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9482

9x6 prop and a 5000mAh 4S battery

4x HS-65MG servos. I originally intended to use HXT900 as I had them but decided it was too expensive a plane to trust to cheap servos

I will use my trusty 1.3Ghz video, OSD Pro combo and Hitec Aurora 9 2.4Ghz radio for now, I am still waiting for Eagle Tree to release the Eagle Link for conversion to long range.

For stabilisation: FY-20A http://www.feiyudz.cn/a/gb2312/product/Flight%20Stabilization%20System/FY-20/2010/0802/3.htmland and AHI http://www.firstpersonview.co.uk/on-screen-displays-osd-gps/s-y-link-eagle-tree-to-fy20a-interface

The build:

I spent a long time reading threads on here and RCG, laying out what would go where and planning everything. I like to do this slowly and I am forever changing my mind what to do. There is never the perfect solution, just lots of different compromises.

Finally got the glue out and started to put it together. Following many tips from the RCG thread, I strengthened each wing with a 300 x 4.5 x 1.4mm carbon strip from between the two main spars out to well beyond the aileron servo. I put these in with medium foam safe CA and then sprayed the kicker, this worked well.



I opened out the channel normally used for the Vtx cable and added a large diameter carbon tube so I can feed cables through this later or change the configuration at any time. I found the tube in my box of junk, for those eagle eyed it is the remains of a carbon tail boom from a TRex 450 that ended it life some time ago, doing the funky chicken.






The glue is drying on the fuselage as I type. I noticed that when I put the sides together using the supplied glue it was easy to take any twist out of the tail relative to the fuselage by over-twisting then it relaxed to the right place. This would not have been so easy with CA or contact adhesive.




So far so good.

[Coyote]

Nice thread Mick, looking very good so far, very usefull links :)

[mark1975]

Very very nice will watch this one closely..

[bignose13]

looking good, i'd think twice about using only a 40 amp esc though, go for something like a 60 or so

[electricmick]

Thanks for the comments, you got me worried over the ESC so I just installed the motor on a temporary mount and tested it using a 10x5 prop and a 4S 5000mAh battery. WOT gives 330w and 21A so the 40A speed controller is plenty big enough. Good as I have already bought it. Feels like plenty of thrust and a lot quieter than the Easy Star with a 6x4 screaming away. I am going to modify the mount so I can use a 10inch prop, size matters, apparently.

[electricmick]

Make a bit more progress today as it was too windy to fly.

Installed the GoPro on the nose.



The 1.3Ghz Vtx is mounted up on top, nearly went for the wing tip but too complicated for now. As it needs 12v I made a voltage step down using 5 1A diodes in series, produces 12.4v on a 4s battery but it gets hot so I may think again. I hate two batteries, bad enough using the one in the GoPro, I would prefer to power that from the main flight battery as well but not sure how, it has a mini-USB for charging but no idea of the voltage or the pin configuration.

Any good ideas for a simple, smooth 12v regulator for the Vtx and another one for the GoPro?



Nice big hole in the side of the fuselage gives access to all the stuff, only a receiver installed so far.



Installed the newly repaired and working FY20A underneath the wing, right on the CofG.



Motor and ESC installed and working well, the ESC hardly gets warm even using the switching BEC





Tested everything and all OK so far, nice clear image with no lines from the ESC. I used a ferrite ring on the ESC lead to the receiver but did not try it without it.

That's all for now folks! Time for a drink......

[mark1975]

God there big arnt they its swallowing the gear lol ..nice build though keep um coming ..

[n00b@FPV]

i have 2 batterys in mine.
i had a light battery for camera trying to save weight but actually needed a larger one for c of g
also bin looking for a 14.8 to 12 step down but i haven't found anything

[electricmick]

A bit more progress on the Skywalker as the weather is so bad.

Tested the FY20A stabilisation system - all working well.



Installed the Eagle Tree OSD Pro, eLogger, plus GPS, Airspeed and Altitude sensors, including the Prandtl pitot tube.



Connected it all up and wow video straight away and eventually acquired a GPS fix in the apartment, close to a window. All appears to be OK. Gently blew at the pitot tube and achieved 70kph. He he.



Almost ready to fly but there are some horizontal lines on the video as the throttle is opened, a sign of RF noise coming from the ESC. I am still using the power feed for the receiver and OSD from the SBEC within the ESC via a ferrite ring but this is not smooth enough. Hopefully a delivery from HobbyKing will be here soon including a UBEC which might be smoother. If not, then I need to make or buy a L-C filter for it. I prefer to use a separate UBEC just in case the ESC dies.

Spend the whole day today updating firmware, doing the Eagle Eyes pan/tilt calibration, setting up and testing RTH via the simulator. Eventually happy with everything, just need to clean up the video feed and it will be ready for the clear blue yonder.


As for a switching regulator to produce 12v, I found one here:

http://www.dimensionengineering.com/

So I have two on their way to me, let you know how they do.

[Gadget Man]

Looking very good

[Coyote]

Very nice build. Theres so much room in there for gear its incredible with the Skywalker. 

[electricmick]

Just tested out the 3A 12v regulator from http://www.dimensionengineering.com/ driving the Vtx from the 4S flight battery.

Excellent result, stable voltage output, no lines on the video and runs super cool. A good find.

[electricmick]

Finally the weather was good enough to get the Skywalker into the air for the first time. The first flight was LOS to check out everything. After launch it need no trimming at all and behaved very docile, the climb rate is not rocket like but good enough for me. I engaged the FY20A and it worked very well in the gusty wind conditions, very pleased. At one point in the flight I held in full left rudder until the Skywalker entered a spiral dive then let go of the sticks, great recovery to straight and level flight. This is the video:

Skywalker maiden 22 April 2011

I then did a 22 min FPV flight which used 1800mAh from the 5000mAh battery. Checked out the RTH which worked really well on the default settings, The only tweak I will do is to increase the gain on the aileron stabilisation on the FY20A to damp out some oscillations induced by the rudder under climb power. Later in the flight got some glitches from the RC and the RTH engaged and turned the plane round, the RC picked up again. Nice to know it all works as designed. No video of the transmitted images as my recorder was playing up, jittery image and lots of hiss.

[llessur]

Hi electricmick,

Nice post, Ive also been building a Sky Walker for fpv, and been following your posted photos with interest. I've been considering the FY20A more for the fails safe aspects of return to base than the stabilization's. The only thing thats putting me off is the cost, would you say this is an essential to protect the investment in the plane?

My spec is

Sky Walker
DX6i
6100 rx
KMS Quantum 2814 /09 830 motor
Ripmax Dragon 45 A ESC
5.8 Ghz VTX 200mw
2x 2200 11.1v lipos in parallel

Also fitted landing gear and tail wheel and added 3mm carbon rods to the wings( my was supposed to be the new version with the additional carbon rods installed)

[Coyote]

Nice first flight, looks very stable :)