FT Cruiser X-57. First Flight.

...hey I made an X-plane. sort of...

Having seen NASA's intriguing X-57 Electric Research Plane, I decided to converted Flitetest's twin-engined FT Cruiser into an RC version of NASA's experimental plane, featuring twin electric motors mounted in the wingtips.

The X-57 actually features 14 motors, twelve small motors with folding props mounted in the leading edge of the wings providing supplementary power for takeoff. The two larger motors installed in the wingtips provide the high-speed cruise propulsion.

I wasn't going to be wiring up fourteen motors, so I dispatched with the dozen leading edge units favouring the simpler hand-launch solution. I used small 89W quad motors (1806 2300kv) running at on a 3S 2200 battery. The propellors are 5x3 props, swinging inwards sweeping air onto the top of the wing to counteracting the wingtip vortex.

This is one of the main benefits of the wingtip design, a second being that the concentrated wingtip flow feeds into the propellor, increasing the dynamic thrust. Finally, additional thrust is generated by virtue of the outside sweep of the prop being unimpeded by the presence of a wing; the prop wash goes into free air.

The modified FT Cruiser with weighs 940g all up, or 749g without battery compared to the spec mass of 766g. The 17g difference is due to reduced wing size, one less servo (rudder servo ditched in favour of differential thrust) and smaller motors. However, 7g ballast had to be added to the nose for CoG correction due to the motors being set rearwards compared to the standard Cruiser configuration.

The motors generate a combined 710g of thrust as installed, sufficient for cruise but certainly not 3D flight. Static thrust of a commercial aircraft is a quarter of its loaded weight and around half of its empty weight. In the case of the xCruiser this would equate to 235g to 470g respectively. So it's comfortably powered in aircraft terms although less so in RC terms where closer to 100% is nice-to-have...

Power Up

...a battery of changes

My spare battery, having thus far survived several crashes in the Floater Jet, finally succumbed to serial abuse when I forgot to disconnect it after a flight. As usual with depleted batteries, I bumped up the voltage by charging it on the Accucell charger as a NiMH, then switching over to LiPO-charge. However, this time, the charger only recognised two cells.

I'm not sure what has happened, but checking the voltage on the balance lead of my good battery in comparison confirmed that one cell was giving no voltage. I have checked to see if perhaps there was a short or something with the leads on the individual cells but have had no luck.

So I've ordered two new batteries, opting for 2200mAh Turnigy units. This is the same rating but a larger capacity than my current 1800mAh battery. The main reason for the upgrade is not the capacity but the curious fact that the 2200mAh battery is shorter than my the 1800mAh, which only just clears the servos arms at full travel, even when pushed right up against the motor.

One concern, though, is that it weighs about thirty grams more than the 1800mAh battery, and it's located right up front. This is also the reason I didn't go for a higher C-rating, as these each weigh progressively more.

What may offer compensation for the increased mass is that I've noticed that the Walrus seems to generate more lift with the carbon propellor, perhaps because the larger spread of prop-wash from the bigger diameter generates more lift from the wings? Anyway, the batteries are still a few days away so we have time for some subconscious deliberation before then.

However, I'm generally thinking that the first launch will be with a good throw and plenty of power, just to make sure it doesn't plough in...

Carbon Fibre Propellor on the Walrus

...and it looks groovy

With the parcel safely retrieved from the post office, I fitted the 10x6 carbon fibre prop to the Walrus last night. It was really easy to change the blades, just two screws to be removed and taking only a couple of minutes.

The blades fit perfectly and look brilliant. They are quite a bit bigger than the standard Walrus blades but I tried running the motor and it handles the extra load quite happily.

The finish of the blade is much better than the plastic original which, to be quite honest, is quite crappy. And, of course, the carbon weave looks good...

Serenity at High Altitude

...an extraordinary flight


I had a completely serene flying experience this morning.

The weather was heavily overcast with a multitude of textures and colours of heavy rain clouds covering the sky. It was almost completely still with just the slightest suggestion of a breeze on the ground with a feel of the moisture in the air.

I threw the Walrus up and did a bit of aerobatics to warm up the servos and them did a run over the kangaroo ground to see how they were doing. Having completed these missions I was wondering what was next, so set the Walrus with a hint of up-elevator with moderate throttle and let it go.

With the cool morning air the Walrus climbed quickly and steadily until it was just a snippet of a plane high in the air, communing with the clouds.

A wing of Sacred Ibis flew over in a perfect V-formation heading north, their pale colouring contrasting with the dark clouds above them.

I took this restful opportunity to take the first ever photo of the Walrus flying as up till now I haven't wanted to take the risk...

Propellor Held Hostage

...noooooo!


Came home this afternoon to find a delivery card for a parcel - my carbon propellor, excellent! It was ten past five, and the post office closes at five. Gnashing of teeth, kicking of things...

Very annoying as I would get good use out of the propellor on the Walrus, while it would be of absolutely no use to the post office, so really I should be allowed to go and get it based on these grounds.

Seems a reasonable-enough argument I think...

Warping Walrus

...wing warping of the unexpected kind

The sudden onset of warm weather has had an unexpected outcome - the Walrus has gone soft!

I've had the plane in the back of my car virtually since I've had it with little ill effect. However, with the last couple of days been moderately warm (only in the low twenties) the right wing tip has warped where it was pushed against the car. This caused the Walrus to have a right turn yesterday, and this afternoon again although worse.

I have taken to putting in a few cushions to, well, cushion and support the plane so there is less stress on it. I wonder if this is a common issue, and if there is some solution to the problem? The obvious remedy is to not have it in the car, although this would also mean forgoing the best opportunities to fly. 

So I'll have to give this some thought. Perhaps some sort of aeroplane bed?

Ridge Flying

...but not terribly successfully

I tried out a bit of ridge flying this afternoon, hoping to get some lift from the gentle southerly blowing up the bank to the sports fields. It's not hugely elevated - perhaps fifteen metres or so, but I was hoping it might be sufficient to generate at least model-sized wave lift.

It was the first afternoon that I've flown the Walrus, in fact I think it's the first time I've flown anything in the afternoon, so I was a little nervous. Warm, breezy...

I launched the Walrus directly onto the ridge and it was immediately apparent that this wasn't going to be an afternoon in the park. Despite the breeze fairly smooth and gentle it still make flying conditions fairly challenging. It also didn't help that there was a large tree just at the edge of the field, in the middle of what would be the optimum ridge flying route.

So I flew the Walrus for a while trying to get some lift but eventually gave it up, any lift that might have been there certainly not compensating for the effort and risk. So I turned back over to the field to end the afternoon's flying in more gentle conditions...

In the Air

...with a little help from providence

I arrived at the field this morning to find it absolutely still and calm, a perfect sunny morning. So I happily unloaded the Walrus and set about getting it ready. I plugged the battery in then switched on the radio. The receiver lights came on but there was a lot more beeping than usual, and then the ESC started playing tunes...this was definitely not right.

A quick glance at my transmitter solved the riddle - it had shifted in the car over the weekend and the throttle was on full, setting the ESC in programming mode. Hastily I flicked the throttle off and checked the controls. Everything was working, excellent. Holding the Walrus aloft for pre-flight throttle check. No response. I'd somehow reprogrammed the ESC to isolate the motor.

So, standing at the field with a plane on a perfect flying morning, unable to fly because I'd disabled the plane...

I set about trying to reprogram the ESC with little hope of success, considering there are about half a dozen options identified only by a sequence of tones. First attempt made no improvement. Deep breath, yell of frustration and then try again. 

Mentally picturing when I had changed the throttle earlier, I pushed the lever down and then powered the transmitter off and on.

Lifting the Walrus up I flicked the throttle and success! The propellor powered up, and we were back in business. Prayer of thanks and the glider was flying into the clean morning air...

Maybe Tomorrow?

...looking good for calmer weather

Today was breezy from start to finish, so flying wasn't even in the picture. However the wind has now died down and tomorrow morning is forecast to be calm, so we should be good to get into the air again.

I'm wondering whether to fly at the paddocks or go to the sports fields, where I had that really good flight. That makes me want to return there, but on the other hand there's the possibility that if I fly there again it might not be so nice again. I might just see how I feel tomorrow...

One thing I want to try is flying inverted. I've done a few barrel rolls, which the Walrus really well, so I might see if I can do half a roll and see how it goes staying upside down. I could even try a negative-G pull-up...

The Best Made Plans

...end up sleeping-in on a Saturday morning

Well, so much for flying with the hot-air balloons. I woke up at quarter to seven this morning and lay still, checking of I could hear anything outside. No branches rustling, no gusts of wind against the window. All seemed quite and peaceful about. 

Also very peaceful under the blankets. Too peaceful. Not to mention warm and snug. I'd gone to bed too late the night before so didn't feel like getting up. Plus the impending disruption of the tiler made for less than conducive circumstances to bolt out of bed and dash off in search of an empty field.

So tomorrow morning, if it's calm, I plan to take the Walrus out to the field and do a little flying. And the hot air balloons might be there again...

Grounded

...by the windy weather

Been a few days now on the ground with the windy weather putting flying out of the question. So I am settling for enjoying happy snaps on my desktop picture, this is the one I'm enjoying at the moment

I have also enjoyed not having to fix gliders I've smashed and hope things stay this peaceful. I have been giving the Walrus free reign when possible, but have also been very sure I'm not pushing my capabilities without ample scope for recovery, in case anything should go wrong. I also haven't dared take a photo of the Walrus in the air lest that should be tempting providence just a little too much.

So, it looks like suburban flying will be on the menu, it's just a matter of coordinating weather and time. Tomorrow morning looks like it may have potential. If it's calm we might meet the hot air balloons again, and I'll make sure to switch the camera on this time...

Retrovision

...looking back at my happy snaps

Looking out of the skylight at home I could see the tops of the trees heaving about in the wind, so definitely no flying this morning, unfortunately.

I was looking  through the Walrus splurb again last night and saw that it's actually mentions the aircraft's capability to fly extremely slowly with flaps down. Well, seems we both came to the same conclusion, except that I haven't had a chance to give it a go as a flight aid as opposed to just for landing.

As an antidote to lack of flying I have taken to using my flying photos as a background on my work computer. I've currently got this gorgeous image of the Phoenix 2000 cruising in past a burnished sunrise...

Its nice to look back through these photos to relive the exquisite sunrises, misty mornings and serenity of the gliders' flight...

Evening Rain

...four seasons in one day

The breezy morning turned into an immaculate day, becoming an overcast afternoon which  developed into showers, finally becoming an evening of settled rain. At this rate I can't see much change of getting into the air tomorrow.

Anyhow, it's nice to be inside listening to the patter of rain on the roof and garden, particularly as it's been a week or two since we've had any rain to mention...

Antenna Fix

...put a pin in it

The pin had somehow fallen out of the antenna joint on my DX5e, meaning the end piece would often come loose while setting the angle. I wasn't sure where I could find a replacement pin and didn't want to  have to buy a whole antenna replacement kit.

Foraging around in the cupboard I came across a cheap household fasteners kit, which included a slim black nail, a near perfect fit for the hole, slightly tight so it wouldn't fall out. It was a little too long, but a quick trim with a pair of side cutters sorted that out.

Now the DX5e's antenna's sorted out, I hope I can fix the chatter issue with a bit of a clean-up of the aileron potentiometer...

A Bit Too Windy

...so we'll just have to think about flying for now

No flying today unfortunately as it was too windy. I stopped in at the field just to be sure, but one look at the treetops waving in the wind was enough to convince me to turn around!

I have reduced the flap travel from one hundred percent to sixty five. I haven't checked this on the Walrus yet as I reprogrammed it while I was waiting at a traffic light. Anyway, I'm very interested to try as I think this will give the best of both worlds at the flip of a switch! Well that's the theory anyway, hope to be able give it a try soon...

Raven' On

...up with the birds

Had a lovely flight this morning, with just the gentlest of breezes coming through. With my revised control settings with expo now at a more pedestrian forty percent, I managed my first loop in the Walrus and my first ever barrel-roll!

In a repeat of my first flight in the Phoenix 2000 I had a couple of ravens chasing the plane. I was a little too far away to be able to judge the distances well, but I had a little play with the birds which was fun.

On my first approach for landing I deployed the flaps when the Walrus was above the field. The result was the plane rearing nose-high, another repeat of my early Phoenix flights.

Fortunately I managed to recover to put the Walrus down for a landing which was a little rough, but functional. So I think I'll be moderating the flap travel so the effects are a bit muted as we definitely don't want a repeat of that again...

In a Flap

...and a bit of flying

I managed to get the Walrus up this morning, although the breeze was already starting to pick up by that time.

I had a minor incident this morning when I accidentally launched with flaps deployed. I must have snagged the lever, most likely when setting the throttle for launch. Anyway, it went up fine, as you would expect with the extra lift, but then went very floaty and nose-up, a bit like the Floater Jet flies.

I turned it around  into the wind when I spotted that the flaps were deployed, immediately explaining its strange behaviour, so I just shut off the power and pushed the nose down to bring the Walrus in for an unscheduled landing.

A quick check there were no other issues and the Walrus was back in the air, climbing steeply into the steady breeze then turning into a large bank over the paddock with the cattle enjoying their breakfast. The strong breeze quickly pushed the glider downwind and my efforts to bring it back were making little success.

Trimming the nose down a little helped it push through the breeze more successfully, and I felt most relieved as it again approached the field. As always, losing track of the Walrus' orientation at distance is a constant risk, and I'm sure the odd false input will be evident in the videos!

The final bit of fun was trying to get the Walrus down. Having successfully cleared the fence without collecting either the tree or posts I deployed the flaps to steady things down and hopefully settle the Walrus down with the extra drag. However the clean air-frame, even with the RD32 camera atop, continued to surf the breeze until it was clear I wasn't going to make landfall before I reached the bank, so I powered round in a mini circuit for another go, the flaps making the downwind transition flawless. 

I eventually got it down, next to the almost-empty duck pond, a good end to some challenging  flying in the breeze...

Zen Flying Official Trailer

...watch it on YouTube

I had hoped to sneak in a flight this morning but the weather was blustery. And it hasn't improved since, with the metrology reporting wind speeds in excess of sixty kilometres per hour. At that rate the Walrus would have slowly receded into the distance... 

However the day has not been wasted, with cheeryman creating an impressive Zen Flying Official Trailer.

I'll certainly be watching the weather to get the Walrus and camera out to have a good fly, and to collect some video footage which I must admit to enjoy watching afterwards.

I can certainly understand the appeal of FPV flying...

Dodging Lamp Posts

...a brief run on a slalom course

This morning was fairly calm so we headed out for a quick fly with the Walrus, the challenge being to find an empty local field with enough room to move.

We ended up at a large sports ground with three fields end-to-end, promising enough except for the floodlights dotted around. My concern increased soon after launch with a turn to miss a post on the right soon followed by an even sharper turn by the Walrus to avoid its adjacent colleague on the left.

One lap around the pylon circuit was enough, and I brought the Walrus in to land, having to fly around another post in the process. Already freaked out, I mis-corrected the incoming glider's wing-down attitude with an extra dose of the same, resulting in a mild ground loop. No damage, just not particularly elegant.

The control response was also still a bit fast for me, although I again didn't have much opportunity to get comfortable with the plane. I've now set the exponential rate up to forty percent, so we'll try and see if that's sufficiently moderate.

Anyway, I have another field in mind which may be more accommodating, so here's hoping for another window of calm weather...

Too Sensitive

...the expo setup's all good

Last night I set the expo rate on the controls - easy now I'm got used to finding my way round the menus on my DX6i. I set the rate at plus thirty percent which seemed to work well, although I was only flying the Walrus on the desk.

So the controls now look promising, easier to control small movements but still leaving good travel for big manoeuvres, which sounds like a good setup. Now just hoping for another flyable window - very blowy again this morning unfortunately...