GeeBee R3 750mm TRILOGY. PART 2: The Build

...so how does this work?

The GeeBee is a nice-quality kit, with solid EPO fuselage making it a smarter-looking proposition than a Rarebear, for example. While having a simple screw-together construction, it does however its construction poses a few questions.

How does the battery setup work, and where's the best spot for the receiver?

The first question is a puzzler, for me anyway having only had planes with unfettered access to the battery. Obviously, unless you're happy remove the wing every time you fly it, you need the ESC lead to remain in the battery hatch so it's accessible through the small hatch opening.

This I found achievable by mounting the ESC against the side of the fuselage, preventing the lead from falling back into the fuselage. This setup seems quite reliable, although packing the battery in and then feeding in the lead and connectors is still squeezy and awkward.

Regarding the receiver, in this case a twin-antenna Orange R615x, I mounted it in the central fuselage cavity which corresponds to a cavity in the wing moulding above. And, connecting all the servos from the back and the ESC from the front gives a very neat installation.

Next challenge is the bracing wire; five pairs of different length wires needing to be clipped into tiny hooks. Fifteen tediously fiddly minutes later I was finished.

The last trick was spinner and propellor. The latter simply gets tightened with a nut, with the spinner base in behind it. Then the spinner is installed; it comes with double-sided tape but, really, that's never going to hold. So I superglued it in place, with cardboard slipped in behind the base to keep it spaced off the cowling.

With everything in place the little GeeBee was looking good...

Dynam DC-3 And The Battery At The Back

...it's finally finished its migration

This afternoon I finally moved the DC-3's battery right back against the stop and gave it a fly. The only other change was that I flipped the battery around so that the leads were facing forward, so that I can connect the plug without having to remove the battery.

With the leads now facing forward the final move hasn't made much difference, with the centre of gravity at 75mm. The main bonus is that no care is required installing the battery; just slide it right back and you're done.

At 75mm CoG the DC-3 takes off very easily; it basically floats off the ground within a few metres, and it will cruise steadily at a fraction over half throttle. It's glide is also improved, although with power off you need significant elevator input to offset the effect of the wheels, but this would even be the case if you were coming in to land with retracts.

With the elevator now on on 100% travel, the Dak is fully controllable on landing, the final mass shift now allowing it to be floated onto the ground in a most pleasing manner, and provides a margin of safety for correction if you misjudge the sink rate a little.

The only drawback is that the Dak becomes light in the nose at low speeds, mainly evident when cruising into the wind. Here the extra airspeed gets it climbing and, without correction, the climb gets steeper as the negative moment from the undercarriage diminishes with reducing speed.

Left unchecked, the Dak will go into a spectacular vertical stall and then wing-over into a dive. Apart from that it is completely stable; all the aerobatic and stall maneuvers I've tried have not managed to induce any sort of spin or other unstable characteristic.

This seems a small price to pay for much improved behaviour of the Dak by having the battery at the back...

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...

Dynam DC-3 and The Case of The Receding Battery

...and where it stops nobody knows

Having established that the DC-3 was very nose-heavy on its first flight, I have been gradually moving the battery rearwards and assessing the change in flight characteristics with each change.

My ultimate aim was to get the DC-3 to glide reasonably well power-off, however with the amount that I've shifted the battery and with it still being nose-down, although much less than before, I'm wondering whether I'll have to settle for "most improved".

The battery has so far receded a substantial 70mm from its initial position hard up against the front of the recess, and the CoG is now somewhere south of the maximum 65mm suggested by Dynam. Makes me wonder whether they actually ever flew it or whether they just stuck with the theoretical figure and let you figure it out the hard way.

While I understand that CoG is not something made up, the moment-effect of the undercarriage is obviously substantial, exacerbated perhaps by the low-wing configuration of the Dak. And, despite having overstepped the CoG limit by a mile, the Dak is still completely stable; this morning I put it through a series of loops, rolls and stalls and not once did it suggest that it was going unstable or enter into any sort of spin that would have indicated a too-light nose.

And the Dak has been flying much better for it; now happily cruising around at about a third power, and turning much cleaner than the stall-turns evident it its first flight. So I think I'll continue inching the battery backwards, although in much smaller increments, until I've got it flying level without elevator trim, and perhaps even gliding a little better...

DC-3 Centre of gravity

...getting there slowly

This morning I had the DC-3 out again at the field, this time with a revised centre of gravity. The instruction manual indicates 60-65mm and I've been flying at around 60 which clearly doesn't work.

To  correct things I moved the battery 30mm forward which put the cog at pretty much 65mm. Not exactly sure how much difference this was going to make, I left the flap setting and elevator trim unchanged just to be on the safe side.

The takeoff was good, the Dak easing off much more easily now, then started to climb and didn't stop until it was pretty much trying to go vertical. So, clearly, the mass shift makes quite a bit of difference.

After a little panic. I managed to the Dak straight and landed, then I reduced flaps and the elevator trim before trying again.

This time things were much better, wing the Dak cruising around happily. It's still too nose-down to glide very well, making me think I'll ease the battery back a centimetre or two and see how that goes...

Fun with the Trainstar

...I've changed my mind

This morning, cool and overcast with just a hint of a northerly, I took the Trainstar to the field for its second fly back on its wheels. Having suspected the large battery, fitted to give it a little extra punch and duration in floatplane guise, to be a bit heavy it its native guise, I switched to the regulation power pack and sent the Trainstar on its way, needing to give it a nudge to get it rolling in the longish damp grass.

As before the Trainstar was flying nose-down, needing a few clicks of up trim. However, flying it whilst in the process of trimming it, I discovered that it's actually quite entertaining flown needing a little up elevator, like I do the Radjet. What this does, instead of it wafting around the sky, is to change the high-wing cruiser into a ground-hugging machine, flying in low and purposely, not unlike its high-speed brethren except at about a third of the speed.

The lighter battery, also located further back to balance a little better, seemed to make the turns a little cleaner as well, although the Trainstar still drops like a brick as it turns as well as tightening turns as well both of which make it challenging to fly.

I understand that this is a trainer and that good training aircraft challenge you so that you can learn. Nevertheless I'd be amazed if someone could actually to teach themselves to fly with this plane, its got that many quirks...

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...

Radical Dude

...thats hot!

Following on from the successful motor transplant in the Radjet, I wanted to give its very-battered nose a bit of reinforcing, consisting as it did of fragments of foam superglued and bounded by tape, which basically holds everything together. Due to missing bits, however, superglue wasn't really working anymore, however I had a great idea - hot melt!

I have tried this out and it worked brilliantly - basically I have injected all the cavities between the foam pieces full of hot melt which, due to its bulk, fills the voids and bonds everything together. So now the Radjet nose is about as rigid again as it's ever been, although still not quite as pretty as it once was.

I've also wanted an easier way to fit the chubby 4-cell batteries as, in the past, I've had to forcefully ram these into the fuselage. Having some unused hatch hinges and some recently arrived, and long overdue, magnets I've decided to make a battery hatch a bit back from the canopy opening.

So far I've just fitted the hinges to the hatch, then I'll glue this to the fuselage and finally install the magnets, probably hot-melted in place and covered with felt tape to prevent them pulling out.

That will almost complete a substantial overhaul of the high-flying speedster, the last thing it needs in a canopy. If only they stocked spares for the 800...

In the Interim

while the weather is wild...

The extreme tranquility of last week has, unfortunately, been replaced by gusty winds forecast to last for the rest of the week. As such, I haven't ventured out to fly anything, least of all the floatplane.

The larger batteries for the latter are on there way, and I'm looking forward to familiarising myself with the Trainstar floatplane characteristics a bit better. The new batteries should provide significantly longer flight times, but I also think that a more considered flying regime will help keep the chubby floater in the air for longer as well.

Finally in the process of reconstruction, now that I've received the replacement ducted fan, adhesive accelerator and the urge to do it, the Stinger is resuming shape. The pace of the reconstruction is slow as I'm making sure that each rip and crack is properly bonded before proceeding to the next, but also the warnings on the accelerator pack have me evacuating the room after each burst of strawberry-scented aerosol.

The foam should go back into shape reasonably well, and I think I'll smooth out the joins with a bit of filler. The only question marks are against the motor and the servos as to whether those survived the massive impact unscathed. Anyhow, we'll know that when the body has been restored and I get the electrics connected up again...

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...

Trainstar Battery ESC & Receiver Packaging

...there's lots of room

The Trainstar has a very roomy fuselage, so there's bags of room for your equipment. The battery is housed under the nose, held in place with velcro and a velcro strap. The supplied ESC also gets mounted to this tray, alongside the battery.

Under the wing is a huge cavity for locating your, um, receiver and satellite reciever, if you want. The picture is taken from the underside as I have the wings attached. 

As I said there's lots of space...

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...

A New Experience

...which ends well, but in the paddock

This morning was lovely, calm and cool, with the sun just rising as I unpacked the planes. I took the Floater and the Radjet, with the former being backup as the latter can sometimes be a little unpredictable.

As it turned out the little jet launched smoothly and flew beautifully, now nicely balanced and flying straight despite it's torrid history of traumatic crashes and endless repairs. It's more predictable behaviour also makes landing easier, bringing it in on a nice long gliding approach and dropping it gently onto the dewy grass.

Having the Floater I decided to throw that up as well for a more relaxing finish to the morning's flying. Well, it ended up as more of a walk as, with the Floater turning back from the paddock, it began to fly lower and lower. Adding more power to counteract what is often an area with sink, the Floater seemed to make no response and eventually glided down for an auto landing.

Reaching it eventually, after a walk across the field and a hop over the fence, the cause was apparent - flipping the power on, the prop spun up momentarily before lazily winding down.

I'd forgotten to charge the batteries...

Short Circuit

...toasting my electrics

I swapped out the Phoenix ESC's only to discover the new unit was overheating as well. During the brief window of functioning, I checked the controls and found no response from the ailerons, pointing to a short circuit of some description.

I thought the most likely potential to be a smashed servo, however it turned out to be stripped wiring on the servo lead as a result of the crash. Foraging around in my packets of spares I found enough extension leads to make up the length, so now everything seems to be going OK.

Unfortunately, having had to strip the propellor, motor and battery tray out and reassemble them, I wasn't able to finish the wing repair on time. However I am hoping that, with no major unforeseen issues (like not being able to get the wing back on), I should be able to finish the reconstruction this evening and hopefully have the Phoenix 2000 ready for its test flight tomorrow...

First Flight with 2200mAh Battery

...and the carbon prop

The weather this morning had calmed sufficiently to venture out with the Walrus for a flight. Not just any flight, the first flight with the 2200mAh battery installed in the nose.

The Walrus assembly instructions do not provide any particular clues regarding location of the battery. In an attempt to resolve the packaging issues, I had fabricated a battery tray directly behind the motor. This layout is similar to the Phoenix 2000 and worked well with the 1800mAh battery I'd been using.

Lifting the Walrus out of the car I could really feel the extra thirty grams of the larger battery, located well in front of the wings. However I held my resolve not to change-out the new battery for the smaller unit sitting in the car, and headed out. There was a moderate breeze blowing which would help the Walrus to get flying quicker, which was good.

All connected, I set the throttle generously and heaved the Walrus up. I was prepared for various scenarios, being prepared to hit the flaps if necessary to get a bit of emergency height, and perhaps having to nurse the gravid Walrus onto a high-power approach to prevent it from nose-diving.

My concerns, however, proved groundless as the Walrus soared into the air without a hint of imbalance or labouring under the heavier load. If anything, the heavier battery gives the plane a more planted feel in the air, and the higher output combined with the larger carbon prop transform the Walrus from an intermediate trainer to a sports tourer. It's performance is now much more three-dimensional capable of higher speeds and sustaining steep climbs.

With the good news of power and speed one would expect a nasty compromise on approach. However I am relieved to report that the Walrus floated into the breeze for landing absolutely happily, for a landing as easy as any...

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...