More auto tuning

After my last adventure discovering the in's-and-out's of auto-tuning I contacted my mate in Canadia DWGSparky for advice on taming the Skywalker X5 and getting it 'tuned'.

As always he had lots and lots of advice, I soon learnt that the auto-tuning was one of the most important parts of setting up the APM functions and that sometimes they can take quite a while to get right.

Armed with my new found knowledge I set back to the flying field, this time with Stu to help monitor Mission Planner.

Unfortunately we had the same troubles as last week. After many tests the auto-tune mode of virtually unresponsive and the RTL would send the X5 into a terminal death dive.

Frustrated I gave up flying for the morning and sat back drinking my iced coffee watching the other boyz fly. At least the scenery was calming.

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Auto tuning

It's been nearly two months since I last flew the Skywalker X5 (been busy working on the house and garden) so I took her up for a re-familiarisation flight to see how rusty I was after such a long break. It was like riding a bike, no problems at all. :)

Now that the airframe tuned for basic RC it's now time to work on the auto-tune function to get the APM working efficiently. So today the task at hand was to get started on the auto-tuning function.

I started by assigning three flights modes, manual, stabilize and FBWA to see how they performed. Stabilize seemed to work quite nicely, it took the edge off flying the 'squirrelly' X5 and the FBWA mode seemed to work with the bank limiting obvious. Once these flight modes were tested I bought her in and re-assigned the stabilise mode to Auto-tune and FBWA mode to RTL.

Thing's didn't go too smoothly this time around. The auto-tune mode was extremely tough to get any response from, when I changed into the mode the X5 became extremely sluggish and almost impossible to manoeuvre. I moved the control surfaces hard left, hard right and it took several seconds before the X5 could turn around. The speed at which the X5 flies across in front of me meant that I could only attempt an auto-tune mode for about 12-15 seconds before turning it off to do a 180 and fly back in the other direction.

I really wasn't sure if I was getting any 'tuning' done so thought I'd see what happened when I flicked to RTL. The first time I tried it seemed to work, with the X5 changing direction and heading over roughly to where the RTL point on the Mission Planner was set, however it overshot the position, did a slight turn and started to fly away. I panicked and switched back to manual mode.

When I tried RTL again instead of heading to waypoint, the X5 pitched up, did a hard turn and then nosed hard down and increased throttle. I switched back to manual immediately and bought her in.

It seems that auto-tuning was going to be a little tricky.

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First flight with APM

First flight of the Skywalker X5 with APM

Today was the big day, the first test flight for the Skywalker X5 with the APM mounted ..... and it all went superbly! I didn't jump in the air once all the tests were complete, but I did let out a loud WOO HOO.

Firstly I took her up and re-trimmed her in manual, it was a little gusty but got there in the end. Once I was happy with the trims, I tested changing mode to 'stabilise' when I was flying into wind and at altitude. All went fine, there was some difference and she felt like she was definitely tracking a little better. After that I tried 'FBWA' mode and found that one a little un-nerving. The Skywalker X5 is a squirrely thing to fly and when I suddenly didn't have as much control authority as I am used to I got a little scared. Anyway the bank seemed to stop and hold at somewhere around 40 degrees I'd guess and similar with bank, so FBWA seemed to work.



All the gear needed, X5 with APM installed, laptop with Mission Planner, 9XR Tx and backpack

I then bought her in and had a break while Harry and I checked over everything. By this time Stu and Paul arrived at the field so at last I had someone who could monitor the Mission Planner while I flew. I changed the FBWA mode to RTL and took her out for another go. Oh, I made sure a new home point was correctly placed in the Mission Planner and loaded onto the APM.

The launch was a little scary (its ok I was expecting it) as I had just trimmed her for level flight. It was just a slight nose down launch until she got about a foot off the deck then she powered away and climbed just fine.

We went through the first 2 modes again to make sure all was right, and Stu was calling out the G/S, altitude, flight mode etc every so often, all seemed to be working well as what was happening in the air correlated with what was on the laptop screen. The Mission Planner did seem to freeze a few times, but within a few moments came back to life, still not sure what that's about. The time was right so I clicked the RTL (again on and upwind leg and at altitude) and guess what?...... she took herself back over to the position I had marked on the map and started circling! Absolutely exhilarating to watch but again a little un-nerving when you don't have to be hyper focussed on keeping the flying brick airborne. It was only a quick RTL test I didn't have the courage to let it go on for long and shortly after I decided to bring her in, "quit while I am ahead" is exactly what I said to myself!

A massive thank you to David DwgSparky from DIY Drones for all his guidance with setting up and tuning the APM, I really don't think it would have been a success without his help and also to Stu for his expert monitoring.

I'm guessing I'll be doing a few more flights just like this one to get comfortable with the different modes and confident the RTL is going to work correctly and for extended periods of time. This is turning out to be a very exciting adventure.



My trusty co-pilot Harry helping to do pre-flights

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Fully loaded circuits

Coming in for a landing with the Skywalker X5

Now that I have the Skywalker X5 at it's predicted full weight for UAV work (using ballast) I thought it was time to take her our for some circuits to trim her up and get her dialled in.

The new control rods and connections worked a treat, very responsive and I can definitely notice the difference.

Check out the video below;

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Replacing the control rods

The new updated control rods and connections for the Skywalker X5

I have been chatting with David from Air-Vision-Air this last week or so and his biggest tip for setting up the Skywalker X5 well was to replace the control rods!

So I placed my order with HobbyKing, waited a week for it to arrive and today had the time to both switch over the plastic gear servos for new metal ones as well as upgrade the control rods and connections.

I may have gone a little overboard, it all seems to be very heavy duty now compared to what I originally had. That said, geez the control inputs are rock solid now, there is absolutely no 'slop', which is what I had previously. I'm looking forward to taking the X5 out now and seeing the difference.

Thanks David for your advice.



Rock solid control input now, now 'slop' between the servo arm and the elevon control horn

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Loading her up

The 'mockup' of the Canon S110 camera I plan t use.

I felt it was time to load the Skywalker X5 up to the final AUW I expect for when she is flying with APM and camera. So today I created a mock camera out of coreflute, the same size and weight as the original and have mounted that in the Skywalker X5. It's AUW is now 1.25kg.

The 'mockup' camera fitted into position ready for test flight.

It was an anxious first launch now that she was an extra 200g heavier. However it didn't seem to make too much of a difference. We had an 8 knot wind from the SE but all went well.

I took her up for a couple of circuits to trim the Skywalker X5 out at the new weight. It didn't really need much at all, I'm guessing because I balanced her correctly before flight. A couple of extra hand launches and landings to check everything was right and I was happy.

One thing I did notice was that the Skywalker X5 was more stable in the air this time, she wasn't being bounced around like before. This extra weight could be a good thing.

The Skywalker X5 was super stable with the new AUW of 1250g

I only took her up for a few quick circuits as I had Harry with me this morning so we had 'other' more important things to do like run around the paddock and explore the creek line!

All up the Skywalker is launching and flying very well with a new AUW of 1250g.

Harry uncharacteristically shy during a photo shoot

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Basic aeros - testing the flight envelope

Stu and Jas prepping for the flight

Under Stu's guidance I thought I'd run through a few 'basic aeros' today, both to increase my flying skills and test the flight envelope of the Skywalker X5. I have no carbon fibre spars reinforceing my wings so I was interested to see just what they could take.

I wasn't sure how we were going to go as I have very minimal throws on my controls (20%) and I haven't setup dual rates.

Doing a loop was no problems at all, she handled that just fine. However I tried doing a roll and that didn't work, all I got from that was a wingover and a steep bank towards the ground! I might try again next week and this time I'll program in dual rates and test the high rates out.

So I called it quits and decided a few loops would be good enough for me, a successful morning of flying is a tick in the box for me.

Setting up for a loop with the Skywalker X5

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Round and round we go

A stiff hand throw and the Skywalker X5 takes flight 

Hand launching the Skywalker X5 has proved to be the toughest part of testing so far. Getting a reliable launch is a real challenge, she doesn't handle crosswind well and needs a dang hard throw to get her moving.

So today I thought  I'd take the X5 up for a series of circuits, to get as many hand launches in as possible. The drill was launch, do a couple of circuits, land and then repeat. This not only gave me plenty of practice at what is required for a successful hand launch, it also gave me an opportunity to hone my landing skills.

The real gem that I discovered was that after about 20min of running time the batteries started to run lower and hand launching became very dangerous because the takeoff thrust was noticeably less. Not that this is likely to happen in a 'real world' situation, but it's an excellent piece of flight performance data to know.

It wasn't the best landing of the day!

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Beefing up the motor mount

The beefed up motor mount just prior to installation

I've had one too many 'poor launches' which have sent the Skywalker X5 cartwheeling across the field, this has resulted in the top screws being ripped out of the motor mount!

The broken Skywalker X5 motor mount

I guess it was inevitable, whilst the bulkhead for the motor mount glues well to the airframe, the bulkhead it's self is only a thin piece of ply. I expect only one or two screw threads to be gripping the ply and the rest are just sitting in the foam.

Anyway, I decided to 'beef' it all up with a set of longer screws, wall plugs and metal washers and have glue four wall plugs into the foam and have used longer screws.

Hopefully the combination of the new beefed up motor mount and successful launches in future will mean that I have no more problems.



The components used to reinforce for the Skywalker X5 motor mount 

Wall plugs, longer screws and metal washers, all part of the new motor mount

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Stall and spin testing

Pulling the Skywalker X5 up into a stall to create a spin!

Today I had scheduled to do some more flight testing, I needed to see how the Skywalker X5 would behave in a stall and spin. This would be my first time ever testing a model aircraft in a spin!

Overall I was pretty happy with the testing for a couple of different reasons.

Initially I took the X5 up quite high and then started throttling back and giving her up elevator until she stalled. Most of the stalls were quite mild and I could hardly notice much more than a slight nose drop, I was happy with the results.

Next I tried a stall at a lower altitude as well as on a downwind leg, this is where things turned a little pear shape! Yep she stalled alright and she spun, quite hard, what made things worse was that it caught me by surprise, I panicked and instinctively pulled up on the elevators hoping to pull her out of the spiral dive ..... you can guess what happened next can't you, yep she spiralled all the way to the ground head first, POP!

When I went to investigate the damage I was pleasantly surprised, a very slight crinkle in the nose but that was it. I did a five minute check over everything and decided it was all ok and hand launched it back into wind, no worries she took off like a dream. The X5 is one tough mudder!

So, I had received my wake up call and luckily had been given and second chance. Undeterred I took the X5 but up to altitude and induced a series of full spins and recoveries, this time keeping my cool and using the correct spin recovery technique. I have the X5 with a forward CoG so the technique for me was simply let go of the controls, within one full spin rotation the X5 had built up enough airspeed and had broken herself out of the spin, all I had to do was pull up.
 and the recovery was complete.

I continued with the spin recovery practice for a good ten minutes, entering the stall and then a spin  and then recovering. Sometimes I even held the spin for a good three, four maybe five rotations (just to see how she would handle it) before starting the recovery procedure. I declared it a successful testing session and bought her in. I haven't built up the courage to try a low level spin again yet but I will try one again soon.

Next on my list for the flight testing is basic aerobatics, you never know I may need to call on my newly found spin recovery skills then.

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Visibility markings

I added some cloth tape to both sides of the wings in order to give the Skywalker X5 some better visibility when she's in the air. Often with the glare from the sun I would momentarily loose ..... which can be un-nerving. I think I have solved this with some clear markings.

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Fixing the hatch lock down

Everything you'll need to complete this task

The hatch lock down screws have slowly been getting harder and harder to tighten. I'm not sure whether I failed to align them correctly when building the Skywalker X5 or not. Anyway it seems that the screw is made of a harder steel than the bolt/nut and what is happening is the bolt/nut is slowly getting crossed threaded. I think I'd prefer that is was the other way around, the screw broke before the nut as the nut is the one that is cast/glued into the airframe!

The old system with bolt/nut glued under the plywood bulkhead

So I cut the plywood bulkheads off the base of the hatch and took the stock bolt/nut out. I then got a couple of M3 screws and nuts from the hardware store, re-aligned and glued them into place.

I used longer screws and put a nut at the right length along the screw as to tighten the hatch properly. Hopefully this will also help with me not loosing the screws in the field as this time they are longer and therefore easier to find in the grass.

The new system with longer screw, locking nut and double bolt glued to the plywood bulkhead

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Takeoff and Landing Tests

Skywalker X5 initial flight testing

Cousin Tye dropped in today on his way from Alice Springs to Bunbury ..... so it was a good excuse to go for a fly.

Wind was a westerly at a gentle 10km/h today. Today we trimmed the Skywalker X5 up a little more and practiced hand launching as well as landings.

First off the X5 seemed a little tough to trim but we persisted for a few minutes and in the end she flew straight and stable. I'm still getting used to her speed. Landings were straight forward although I can probably come in with less airspeed.

Overall I was very happy with the flight testing, I'm getting more confident with the X5's handling and my abilities. Next time will focus on hand launches and landings again but see if we can test stalls and spins as well.

Successful hand launch

Launch, circuit, go-round and landing

Last landing of the day

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Launching challenges

Catapult bungee setup for launch

Launching wings has been a bit hit and miss for me, until I got my confidence I would often get a wing over and cartwheel them into the ground. Because of these past experiences I was quite nervous about following up on Stu's successful first launch of the Skywalker X5. Developing a system for launching it reliably by myself I knew was going to be a challenge and may possibly involve a few crashes.

I had a bungee catapult in the cupboard so thought it could be a way of getting airborne with the least amount of heartache. The thing with bungee catapults is that they help to give a more consistent launch, something that hand launching is not known for.

So Harry and I built it in the morning (didn't take long) and tested it on the back lawn. I loaded the bungee about half way, connected the X5 to it and got Harry to trigger the foot pedal on my command. The very first time we did it Harry got a little overzealous and stomped on the foot pedal as soon as I asked him to come over and get ready, lucky for me the bungee barely had enough in it to get the X5 off the frame and it flopped onto the grass unharmed. the couple of tests were a little more controlled and we got it to launch a metre or so into my open arms (very serious wicket keeper pose).

With initial tests complete we headed to the Woodbridge flying field for the real deal. It was 32 degrees, the wind was E/SE 19km/h gusting to 27km/h so we had a nice breeze to head into.
The bungee catapult launches were not that successful, all of them resulted in wing overs and one with the X5 doing three cartwheels over the grass, the only saving grace was that I had the wisdom to make them all no-power launches so the inertia was low.

Fed up the bungee catapult I decided to give the old hand launch a crack. Again I decided a few power off glide tests would be prudent before trying a full power launch. The first attempt resulted in a mild right hand wing over but I just managed to recover. I trimmed the aileron and tried again, success! Three more just to make sure I had the right system and all was looking good. I then went the 3/4 power hand launch and she went off like a dream.

She climbed quite quickly and I noticed that the up elevator I had set last week was too much as I could barely make her fly level. I gave her full down trim and the Skywalker X5 felt much better. I flew a couple more circuits, flying across in front of me where I could see how she was responding. Trimmed her up a little more and other than being bounced around a bit by the wind was happy with the end result. I'll now make the current trims permanent mechanical trims and put the Tx trims back to neutral.

It was an excellent flying session and I'm very pleased with what I have learnt. I was really hoping I would be able to reliably launch the X5 without a bungee catapult, for such a small airframe I thought it was going to be a shame to have to lug all the extra gear around. So I'm happy that the catapult didn't work for me but the hand held launching did. The catapult can go back in the cupboard and may come out when I get a much larger airframe to launch.

The next step is to continue to work on perfecting the hand held launch, confirm that the latest settings give a stable flight and practice landings. Hopefully I can get back to the field this week for a good 30min flight of simply taking off, flying a circuit or two then landing and repeating that process over and over again.

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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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