Flitetest X-57. Take 2.

...a long time between drinks

After a long hiatus the X-57 is back in the air and flying OK.

The issue I'd had initially with unbalanced thrust turned out to be only an over-tightened motor mount - backing off a couple of screws was all it took to get the slow motor spinning up to speed.

However, the wings still seem to be generating too much lift, with the X-57 soaring with even modest throttle settings and fairly wanting to loop with anything more than that.

In fact, I had to fly it with negative elevator trim just to try and get it flying level-ish. For my next try I'll use a heavier 4S 3000 to try and even things out a bit.

This may help it fly level and so help to eliminate the problem of the big disparity between power on and power off flight and allow it to glide properly with a bit of airspeed. At the moment when you cut the throttle it stalls which makes trying to land it, well trying...

Radjet 800. First Flight.

...back better than ever

The arrival of the Radjet, my second and a replacement for the much loved and even more battered original, was much anticipated. The pretty original had been the subject of countless crashes as I struggled to learn the secret of getting it into the sky.

Along the way I learned about the delicate balance required with speedsters, and not to get the Radjet into flat spins form which it struggles to escape. I also learned, and relished in, the Radjet's capacity for rock-solid performance and high-speed stability.

My arrival of MkII caused some angst as nearly a year had elapsed since it's predecessor had retired after the incident with the sapling. Fortunately, and remarkably, my lessons learned were so entrenched that the pretty speedster launched and flew virtually perfectly.

Something that I never had the opportunity to appreciated before it was pummeled through launch training, was just was cleanly the Radjet flies, swift cruise at half throttle and effortless acceleration out of dives.

So, despite the nervous anticipation, the Radjet is back and reinforces my perception that this must be one of the best-value foam speedsters around...

Rarebear Funfighter. First Flight.

back in business...

The Rarebear was my second fast plane, after the notoriously hard to launch Radjet. Despite its diminutive caricature proportions, it was blindingly fast and flew on rails. However, as happens, it had it’s share of incidents, including a near lipo fire and a high speed excursion through a barbed wire fence. Finally, battered and weakened beyond stable flight, it was retired to the wall and gradually stripped of it’s internals for new projects.

So it was with great excitement that I came again to consider another Rarebear to join the flying corp. The first time round I’d chosen the PNF version, in the rather dull white and brown livery, but this time I got the ARF kit, unpainted and without decals. This time also I changed the battery; last time I went with the “ballistic upgrade” 45-90C which, when combined with the diminutive current-junkie funfighter motor, makes for epic speed and addictive noise. However it was far too fast in reality, so this time I chose the same 850mAh 4S battery, but in more sedate 25-50C form.

Also, I had a bit of fun rendering the Rarebear into its donor Bearcat regalia; Navy decals with pacific blue paint (a few shades lighter than the real thing). Overall I thought it looked great. Also, importantly, I applied tape to all the hinge lines (excluding the rudder which doesn’t function) to avoid a repeat of the “missing bits” episode of the original.

So to the first flight. Yes, I was nervous. The Rarebear is small, fast and can kick on launch, so certainly not to be taken lightly. So it was with some trepidation that I threw it up on about half throttle and held my breath.

As it turns out, the rare bear was very well behaved, climbing sweetly into the sky; a little steeply because I’d set the elevator up a bit and, after it had levelled off, flew absolutely beautifully, straight and stable, turning with characteristic crispness and climbing with absolute disregard for gravitational dynamics.

In all, the first flight was excellent, the little ‘bear even slowing up for landing without a hint of wing drop, so I’m now looking forward eagerly to pushing the limits towards full throttle, enjoying the subdued howl of the little fighter across the kangaroo paddocks…

Fox Glider with Funfighter Motor.

...back with avengeance

The little Fox glider is a beautiful flier, however mine has always suffered from motor vibration. Even the addition of a supplementary firewall didn't make much difference, so the little Fox was eventually consigned to hang on the wall whilst I decided what to do.

Help came in the form of the forced retirement of the Radjet, and I transplanted the Funfighter motor I'd installed there into the Fox. To complement this I'm using a 1500 4S Zippy compact battery, lightweight enough not to tax the speedy motor but large enough to provide generous flight times for the sleek Fox.

The result is speedy, the slippery Fox now genuinely fast and very quiet, the Funfighter motor providing it with landscape-traversing speed and generous, although not unlimited, vertical climb.

So all in all a simple and very successful transplant, the Fox glider flying with the Radjet's heart...

SR71 Blackbird. First Flight.

...blackbird of noisiness

The SR71 is a Parkjets design, one of those "stickplanes" which combine simple construction with characteristic design cues that define the aircraft.

I chose to do the 125% version, giving a wingspan of 840mm and a length of 1250 and making it quite an impressive aircraft.

I chose to power the Blackbird with a funfighter motor I'd liberated from my old Rarebear. This motor is a little under-specced for a plane this size, yet it managed to give the SR71 a decent turn of speed nonetheless. I was going to use a 1500 4S lipo but, unable to get CoG sorted, opted for a heavier 2200 4S to balance things out.


My main concern approaching launch was not it's flight characteristics which, being a large delta promised to be benign, but the proximity of the handhold to the propellor! Fortunately this concern was unfounded, and the SR71 took to the skies beautifully stably.

As the Blackbird accelerated away, it became apparent that this is a very noisy plane, even noisier than the Radjet with the same motor...

Fun With the FT Viggen.

...fast and fun

The Viggen has proved to be a great addition to the fleet, being fast stable and distinctive in the air. And, all this despite it being my first Flitetest build.

Most amazingly is how easily, and stably, it launches; being flat underneath you have to launch it underhand and yet it climbs stably without threat of stall or spin.

It's benign characteristics are a combination of it being a delta, but also certainly due to the calming effect of the canards, keeping the nose up and reducing the load on the wings.

You can turn the Viggen as sharply as you like and it won't do anything nasty. In fact, so effectively will it turn that it's almost like it has vectored thrust, being able to keep on looping almost about its own length.

And it's quite quick too; my version runs a common-or-garden ebay fan with a 50A ESC and is good for about 100kph. You could load it up with a 12 blade fan although I'm not sure how much aero load you'd want to put on a foam board plane...

Firstar V2. 70mm EDF Conversion.

...flies and sounds better

The flight performance of the Firstar has been very disappointing, mainly I think because of the effect of the negative thrust angle which effectively just increases the wing loading.

So, like I'd long considered with the Floater Jet but never actually did, I've replaced the pusher prop with a low-mounted 70mm EDF installed directly on the body mount used for the stock motor tower with large cable tie straps screwed in place.

The EDF is rated at about 1.2kg thrust, far more than required, so I'm only running it at 60% speed on a 3000 4S lipo, which is more than adequate. In conjunction I've also replaced the stock 30A ESC with a 50A unit.

The thrust line of the EDF is virtually through the centre of lift on the wing, and this shows on launch with the V2 flying straight and then beginning to climb as the speed climbs, in stark contrast to its behavior with the tall pusher prop where it always nosed in and was reluctant to climb.

The much sleeker form, with the tower and foam shroud, means that it's also faster through the air, if required, and glides very well. And, if you needed more benefits, it also sounds brilliant...

Flitetest Viggen. First Flight.

...no bites from the vegan

Preparing for the first flight of the FT Viggen I was both excited and nervous; it looked to be a great flying plane made a little more forgiving with the canards. However, having a completely flat underside, it was also the first plane that I’d ever have to launch underhand.

So, as I’ve done several times before, I headed into the depths of the paddocks to a launch spot with long grass, just in case I needed an arrestor bed. As it turns out not really but it didn’t hurt since, at my first attempt, the trajectory was too flat, and the Viggen simply disappeared gently into the foliage.

The second attempt was good, the Viggen holding an upward attitude till I could bump up the throttle and then it was on its way.

Stinger Ready to Go

...hopefully it will be good

The Stinger has been reconstructed with its new fuselage and replacement fan unit, fitted with a zen-first R615X receiver  and, just yesterday, received its new Nanotech 2200 4S 45-90 power pack.

Apart from it looking sharp and new with the replacement fuselage, and interest in how the new DSMX receiver will work, it's the performance impact that the big nanotech will make that I'm most intrigued in.



And it is big; in fact it's too wide to fit easily into the fuselage, bulging the foam past the matching form of the canopy. I'm hoping that in due course the foam will compress a little to reduce this distortion but there's no denying that there's a lot of battery there.

My experience with 4S nano's on my Rarebear indicate that they offer substantial performance improvements, although I'm not sure whether, in this case, the additional grunt will be offset by the increase in mass over the 1800 40C Zippy I used previously.

Anyhow, I'm very interested to try out the reborn Stinger. I had, in fact, been hoping to get it out this afternoon for a test run but the weather wasn't cooperating with overcast and windy weather. Lets hope there's a mild and sunny afternoon in the offing soon...

Radjet. New Look. Big Battery.

...good and not so good

The little 850 4S lipo that had served the Radjet well finally went to battery heaven which left me pondering what to do. However, with the Stinger in pieces under the table awaiting a new fuselage, the obvious option was to adopt that.

I'd flown the Radjet once before with the 1800 4S; it flew OK although the battery is a little oversized, and it also didn't quite fit in with the small hatch I'd made to fit the battery in with the Radjet's reconfigured nose.

So I made a second magnetic hatch, which allowed the big battery to be inserted with ease, being pushed into the front fuselage just enough to secure it and allow balance to be set.

As before, the extra weight shows, with the Radjet needing a little up-elevator trim to compensate. Also, although the battery has a 40C rating, it still doesn't deliver the kick that the little 45-90 nanotech does.

But the Radjet still flies well and, with its sleeker lines, isn't much off the pace. A bonus with the big pack is that the Radjet now flies flat out for longer...

Ultimate Stinger Smash

...now I know why I was cautious

Yesterday morning I packed the Stinger for its inaugural outing with its latest colour scheme; the two red stripes supplemented with a third stripe in black, which I hoped would embolden the graphics as well as broaden it.

The morning was beautiful, cool and still with hints of mist on the lower ground. I managed to launch the Stinger a little straighter, although with a minor wobble, and I had it swooping across the field and climbing steeply into the air.

The supplemented graphics seemed to be working better, so I decided I'd be a little more adventurous with the flight manoeuvres. Despite the thrilling sound and dashing looks, I usually fly the Stinger quite conservatively because of the orientation issue; in fact flying on the Radjet turned out to be much more entertaining.

I did a few high-G pulls and then looped the Stinger down for a low pass overhead. However, when it was coming down, I somehow got confused as to which way it was facing. I'm not sure whether it was that I could see the reverse markings through the wing, but the split-second mystery was enough to cause panic, hitting full elevator in a desperate hope for salvation.

I'm really not sure exactly what happened then, however I do know that shortly afterwards the Stinger smote the ground mightily, disintegrating into high-speed debris. I'm thinking it's going to need a new fuselage...

Radjet Test Flight with 4S 1800 Battery

...without disaster or mishap

This afternoon was gorgeous and sunny, slightly warm with a gentle breeze from the south west, perfect for letting the recently-refurbished Radjet loose with its boisterous battery pack, the 1800 4S 40C borrowed from the Stinger.

As mentioned previously, I'd had several concerns relating it being too heavy with the oversize battery or simply bursting into flames due to the ESC being overworked. Fortunately, neither happened, with the Radjet taking to the skies without incident and flying well.

I did a few circuits before bringing it down, needing to make a few adjustment to the elevator settings after the servo change, and also to dial in a little more expo with the new servos having a bit more travel than before. Having sorted out the details, I threw the Radjet up again to give it another run.

The battery, significantly larger than the recommended 1300 and substantially larger than the 850 I'd been using, is rather oversized for the power system and changes the characteristics of the Radjet into something of a grand tourer. I think a 1300 4S battery is probably the ticket, providing enough current and flight-time without carrying any excess.

So, while this exercise answered one nagging question, it also raised another; considering it can comfortably carry the 1800, what if you uprated the motor and the ESC...

Radjet with Big Battery

...and a servo upgrade

Following my conversion of the Radjet to give it a battery hatch for easier insertion of the chubbier 4S batteries, I was playing around the other day and discovered I could actually get an 1800mAh battery in without much effort. This was rather remarkable and something I had thought of doing before but never taken much further as I thought it unfeasible.

My concerns are that the sustained current supply from the larger battery might overwhelm the stock ESC, and the other that the additional weight might cause issues with the Radjet, especially on launch. Regarding the former, the 1800 is a 40C while the little 850 is a 45-90C, so I don't think there should be too much difference, except for duration. To hopefully reduce the heat-load, I have installed an extra cooling port (slurpee straw) directed straight onto the ESC and of course the Radjet runs without a canopy these days.

In the case of the latter, I think the Radjet should be OK with the mass, considering the Stinger runs with this battery on a smaller wing area and with a heavier body.

I've also replaced the original wing servos with Turnigy TG9z's due to these stripping when I pancaked the Radjet on its most recent flight. I'd bought these servos as the HXT 900's were out of stock and, while expecting much the same, I was amazed when first powering these up at how quiet they were in comparison. I gather these are not quite as strong as the HXT's, however they should are well rated and sound super-smooth!

So, since today was just way too windy from start to finish, I'm hoping that I might be able to get the Radjet into the air tomorrow and see how it goes...

Rarebear Best Battery

...finding the sweet spot

I'd bought the Rarebear along with the suggested "ballistic" upgrade battery, the 4S nanotech 45-90C, which promised incredible performance. They were quite right, except the little plane end up being so fast that I can't possibly fly it at that speed, spending most of the time just over half throttle and occasionally bumping it to around two-thirds.

However I have done a battery swap with the Radjet, flying that on the little 4S's and running the Rarebear on the 3S 1300's. This afternoon I flew the Rarebear twice, firstly on a 25-35C and then on a 25-50C. One wouldn't expect much difference, however the 25-50C is, in my opinion, the perfect battery for the Rarebear; it makes the plane significantly fast enough to keep you on your toes but remains controllable enough to make super-low flyby's at full throttle, which is how I like to fly my fast planes.

Anyway, so I think the swap will be permanent, the Rarebear happily swooping around on the 3S and the Radjet screaming around on 4S...

Radjet on 4S Battery

...giving the Radjet a bit of zing

I took the Radjet out this afternoon, having fun surfing a strong northerly breeze. Having depleted both batteries, and thinking the conditions a little extreme for the Phoenix, I pondered what i could do. Mentally reviewing my other spare batteries, one possibility presented itself.

The Radjet has been getting a bit slow lately; I'm not sure why but not being able to access the ESC or motor, I haven't been able to do any checks. My thought now was to try it out with one of the Rarebear's batteries; although diminutive they are four cell, which would give the Radjet a bit of a kick. Or make the ESC explode. Or melt the motor.

The 4S batteries are quite chubby, not unlike the Rarebear itself, so this was the first test. Amazingly enough, the battery fitted in the Radjet's fuselage, just. The next test would be when the power was connected. Actually, plugging in the battery had the ESC giving an extra beep, encouragingly recognising the extra cell in the battery.

Having given the controls a quick check, I flipped on the power somewhat hesitantly, not really knowing what to expect. The motor spun up, a little more energetically, then I cranked it up to two thirds and heaved the little plane skywards.

Hitting full power about halfway through launch, the faster prop speed was immediately obvious, as was the energy with which the Radjet was carving up the skies. While not massively fast, it was still considerably faster, and the return of its crackling propellor note was most welcome.

I think the 4S will be a regular occurrence with the Radjet from now on, turning the radjet back into the hooligan it always was...

Stinger 64 First Flight

...and no crashes!

Today I had the first flight of my Stinger 64 EDF, running in on a Zippy Flightmax 1800mAh battery, although I believe some people fly it with a 2200mAh power pack.

The first launch wasn't good; I'd watched some launch videos and concluded that it needed full power as well as some correction for roll on launch. Well, it does need full power but the roll correction's a another story.

I'd launched it in a similar fashion to the Radjet, with about two-thirds right aileron. I'd also read that the Stinger was quite sensitive to control input, so I'd set it on low rates with expo. It turned out that the torque reaction wasn't nearly as severe as I'd expected and my low rates were still much too high for aileron.

The result was that, on the first launch, the Stinger was inverted at about four metres above the ground. Fortunately, with experience in this regard with the Radjet, I was able to correct it and then bring it in for a landing. I launched it again, without dialled-in aileron, which was OK, needing just a dab of correction.

The ailerons continued to be extremely sensitive, flying on full power, leading to a few harrowing moments, although fortunately I managed to keep it in the air. My first impressions of the Stinger, aside from the over-sensitive controls, were that it was fast but not super-powerful.

Having said that, its climb rate and general pace were quite impressive, and the EDF sounds really good. The landing wasn't great - I over-flared it on approach, but still got it down OK.

So, for the next flight, I am setting both ailerons a tiny bit down to give a bit of extra lift, and I'm going to add a little up elevator. I've also set my rates down by ten percent. In combination, that should make the Stinger a little easier to control and more fun to fly...

Stinger Assembled

...but servo centering still a pain

I finished off the assembly of the Stinger 64 EDF today; a very nice quality kit that goes together well. The only piece that doesn't really fit is the pink trim bit that fits between the fuselage spine and the tail.

Something I wasn't sure about was the installation of the EDF, as I suspected the fan, or at least the cowling, would vibrate. So, to be on the safe side, I hot-glued the cowling to the fan housing in a few places, and then glued the cowling into the fuselage before I installed the wing.

The only thing that was a pain, although not unique to the Stinger, was the servo centring. In the past I've had to reinstall the servo arms so that they're centred once the plane has been powered up. I thought I was missing something, but checking a few videos of this subject seemed to confirm this.

The problem is that, in the case of the Stinger and the Walrus, the servos are installed in recesses without access to the servo arm, so I ended having to cut a section of foam out from one tail servo. In the case of the tail there's no option as, like flaps, they both move together and there's no trimming option.

I have read about a servo tester which includes a facility to set your servo to the centre position. I think this lets you set the centre position so as to install servo arms prior to installing the servo on the plane, however it doesn't help with servos already installed on a plane. 

Perhaps the plane manufacturers should use this instead of just randomly installing the servo arms...

Rarebear Ready

...not sure I am though

The Rarebear has been assembled, not that the assembly required is that extensive - just the vertical stabiliser/rear fuselage and horizontal stabiliser. The extra bit of fiddling around that was required in this case is to fit the 850mAh 4S battery into the front compartment. While this is just a matter of removing foam, it is rather annoying, especially as this is the ballistic upgrade they suggest...

Nevertheless the chunky battery is now accommodated, the ESC slotted in and the controls hooked up and trimmed. I have run up the motor and it's ferocious. The manual suggests launching the Rarebear at full throttle on a 3S pack, so perhaps three-quarters would be appropriate with the 4S.

Anyway, hopefully the breeze will drop tomorrow and I'll give it a go at the paddock where there's lots of clear space. I think I'll need it...