Dynam DC-3 1470mm. FPV Video Link Crash

...that didn't end well

Having been doing laps of the paddocks with the Floater Jet in an effort to fine tune the mobius FPV system and maximise the range, I decided to give the system a try on the DC-3 because this would sit the transmitter further away from motors and battery than was possible in the confines of the Floater Jet.

I must admit having some misgivings about this venture as the DC-3, in this fixed-undercarriage guise anyway, is a rather unstable platform, having a tendency to nose up heading into the wind or on too much throttle, ending up in a dramatic stall as is ries to climb ever more steeply.

The flight went OK until, at the extreme of range, the DC-3 flew in the radio shadow of the tree bordering the field. Usually I'd been more careful and stood in the middle of the paddocks to  avoid just such an event. Being at the limits of transmission, the modest tree, that one which I have flown into numerous times, was sufficient to completely block the video signal. I cut power and it dipped a little, then started to climb.

When the video flashed back on all I could see was blue sky. Dipping down again, I have slight glimpses from the camera, desperately trying to compensate the increasingly wild flight of the Dakota.

Unfortunately the video never restored sufficiently, the signal failing again before, finally, there was just static as I stood, still holding the elevator down, just in case it may still help...

Dynam DC 3 Dakota 1470mm. Clouds.

...beautiful afternoon

My favourite flying conditions, usually, are when it's sunny with interesting clouds. This afternoon was also quite windy and gusty, not unpleasantly so but not ideal for the Dynam DC3 which isn't as stable and docile as one would imagine.

Nevertheless, with developing clouds sweeping across the field, it made for a wonderful backdrop to cruising the DC3 around.

Despite twin props, the DC3 doesn't even approach being rapid, so full-throttle flypasts are moderately brisk accompanied by a faint high-pitched whine.

But it's still good to punt around, and of course looks the deal even if it's nastier to fly than the full-scale original...

Dynam DC 3 Dakota 1470mm. With Ventral Mobius Camera

...a novel point of view

I'd never flown the DC-3 with an on board camera, mainly because I didn't want to have an ugly patch of velcro on top of the fuselage, and also being so rounded there's not really a good spot. And then there's the cockpit antenna which would get in the way.

Anyhow, the other day I decided I'd try something a little different; putting the mobius under the fuselage, slap bang in the middle of the wing section. I hadn't done a test run of this beforehand, but gave it a go nevertheless.

The result isn't bad, if a little closed-in, giving a nice view of the props. If I tried it again I'd put the camera a little more forward. The best bit, I thought though, was after landing hearing the motors winding down and seeing the props tick to a standstill...

Dynam DC-3 Dakota 1470mm. Spectacular Sunny Afternoon

...a pleasant sunny afternoon

Monday morning was grey and miserable but, just to be sure, I packed the DC-3 and Radjet. This was just as well because, by lunch time, the weather had cleared to a beautifully sunny and mild afternoon and I would have been most upset to have been flightless.

Happily I headed to the field with the afternoon winter sun flooding the fields with warm afternoon light as it began to dip towards the western horizon.

The DC-3 is a docile creature suited to slow flypasts and modest aerobatics, so I spent an enjoyable quarter of an hour doing just that. I managed a really nice touch and go as well as a fast flypast.

Being quite slow I have been pondering a few possibilities to see if it can be made a little speedier, but we'll keep those musings for another day...

Dynam DC 3. Low Flypasts & Misty Sunrise.

...beautiful morning for flying

Clear still mornings are perfect for flying and, when the clear night provides a light blanket of mist on the paddocks, it's even better.

The other morning was exactly that, and I had the DC-3 out for a bit of enjoyable low cruising around the field and over the misty paddocks.

The DC-3 is now flying very pleasantly; in fact it doesn't really do much more than that. Most of my aircraft, even the Raptor or the Canadair, have got a bit of grunt and, at full throttle are quite quick, even fast in the case of the latter.

The DC-3, however, with its factory-spec motors, is quite pedestrian. In fact, one could miss the difference between going from half throttle to full if one wasn't paying attention, so moderate is its performance. And that's with exactly the same battery as powers the also-twin engined Canadair.

And yet, punting the Dak slowly and gracefully around the field is quite entertaining, and you get to enjoy a variety of classic views; head-on, side view and, of course, the instantly identifiable outline of its beautifully curvy wings...

Dynam DC-3 Instability

...but no damage

The hot air balloons were out again this morning, their rotund forms dark in the distance as I crested the hill, the occasional bust of light from the burners illuminating what was otherwise a fairly dull and cloudy morning.

At the field things had brightened up a little, and I had the DC-3 lifting off easily and buzzing around the field. Towards the end of the flight I was playing around with it a bit more, with high-speed passes (or rather, full-power passes, as the Dak is fairly pedestrian) and some steep climbs, trying to get it hanging off the props.

During one of the latter attempts, the DC-3 went into an alarmingly severe spin, the first time its even done this. As usual, I let it drop to gather airspeed and it corrected itself almost immediately without requiring any correction from my side.

So, a little alarming but nevertheless good to discover that the instability exists, but equally that it's only evident in extremis and easily corrected, as long as you have a little height to spare...

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...

DC-3. Morning Clouds.

...surprise and delight

A couple of days ago the weather quietened enough to take the DC-3 along for a morning flight. Although calm enough to fly, a grey blanket of cloud and the imminent threat of rain wasn't a promising outlook.

A few large raindrops beginning to fall as I unpacked the Dak, determined to get a quick flight in if possible. Fortunately the rain held off and, more surprisingly, the heavy clouds has dissipated sufficiently for the dawn to illuminate firstly the adjacent clouds and then, a little later, those floating on the opposite horizon.

The clouds didn't clear enough to actually get any sun, so conditions were a little dull. However it was nevertheless a lovely morning's flying; a beautiful morning cloud show always turning an outing into a special occasion...

DC-3 at 70mm CoG

...and flying well!

Yesterday, I again nudged the DC-3's battery a little rearwards, with the front of the battery now a distant 70mm from the front of the tray, equating to a CoG of 70mm from the leading edge, and found the DC-3 still flew happily.

The take-off was really good, you never really know how well it's going to turn out, and I enjoyed buzzing it around the field, enjoying the clouds starting to catch the light of the rising sun, first those in the east followed by those in the west.

The Dak flies very easily now, although I will do some more experimentation with turns, where it can tend to go into a stall-type turn, perhaps just needing extra rudder to boot it around at lower speeds. Also, I'll also do some sore stalls and spins to see whether the the light nose leads to any instability at low speed...

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...

Dynam DC-3. Take-Off with Flaps.

...much better

This morning, after carting the DC-3 around in the car for two days, I finally had the opportunity to get the Dak into the air again with an immaculate morning; clear blue skies and absolutely still.

I'd decided that it needed flaps for take-off and perhaps then, once up to speed, retracting flaps and flying clean would be OK. As it turned out, I left the flaps on for the whole flight as it was flying quite happily with them deployed, and the additional lift transformed the Dak into a lovely easy flyer.

The Dynam DC-3 doesn't actually have flaps, but using dualaileron mix and plugging the aileron servos in separately you get flaps automatically configured, although I needed a bit of messing around with reversing to get everything working as it should.

I'm still a little concerned that it needs flaps and elevator trim to keep flying, so I might adjust the centre of gravity for the next flight and see how it goes; I think I'm at the front limit of what's suggested when it seems like I should be at the back.

At the moment the Dak simply plummets when you cut power, which makes it a nerve-wracking proposition if the battery runs low...

DC-3. OK So Lets Try Again.

...and see if we can get it


Following on from the first flight where the characteristics of the DC-3 were anything but the easy-flying plane I thought it would be, I'm now considering whether it needs to be flown like a real one - take-off with flaps and then high-speed cruising, in order that the plane's developing sufficient lift without having to be constantly on the elevator and throttle.

I had the DC-3 ready yesterday, but unfortunately that coincided with the end of two beautiful sunny and calm days, and the start of the wind; although that cleared the skies it didn't do much for my flying prospects.

Nevertheless I'm hopeful of getting the Dak airborne over the next few days to try out my theory to see if I've "got it"...

Dynam DC-3. First Flight.

...disappointment with a crash

I finished the DC-3 yesterday and today had been looking for the wind today to die down, being a beautifully sunny and mild day.

By early evening the wind has abated sufficiently to haul the Skybus off the desk and into the car. It's certainly the most appealing aircraft I've put together, with bags of character and that distinctive look that's known the world over.

Despite that docile appearance of the plane I was nervous; mainly because of the proximity of the props to the ground and taking off from grass exacerbating the risk.

At the the breeze was a little stronger than I'd like for an unknown aircraft, but I at least wanted to get the DC-3 taxiing. First attempts showed the wheels were catching on the grass but, after shifting the plane, managed to get it going and, with the Skybus buzzing along happily, I upped the power and eased off the elevator as it started lifting off.

My initial thoughts were that it flies like a bit of a dog. And, as the flight progressed, this impression didn't improve much; it seems cumbersome, doesn't turn easily and goes into a stall-turn when you try and power it out.

Added to this the moderately gusty conditions didn't help. Finally, thinking flaps would help, having set it up with dual-ailerons, I hit the switch and immediately regretted it; I'd set it up with negative elevator to balance the tail, but too much, which sent the DC-3 nosing down as if on an emergency approach.

Flicking off the switch, I cut power and readied for landing, it being on approach already after the flap incident. Expecting it to float in for landing, instead something went very wrong.

I'm not exactly sure what, although I'll get a better idea when I check the video of the flight, but the DC-3 dug in a wing tip and cartwheeled dramatically. I was expecting major damage, but this appeared to be limited to the dented wing tip, two snapped props (spares fortunately provided) and a dislodged motor requiring re-gluing.

So, the appeal of the Skybus rather tainted, it'll be a video review to figure out what happened before hauling it out for another go and trying to decipher the mysteries of flying the Dakota... 

Dynam DC3 Build

...starting to take shape

So far I haven't actually done much assembly of the DC-3, although I have done lots of spraying; I've decided to spray the wings, underside of the fuselage and horizontal stabiliser in aluminium metallic paint to mimic the general colour scheme of the commercial DC-3 airliners of the day.

Surprisingly, the spray-painting has gone quite well, even the tricky masking line of the fuselage. Now, with the painting pretty much done, I've just started the gluing process, with the first being the control horn bar of the elevator.

Next, I'll be gluing in the tail surfaces and then the biggie, gluing the wing halves together making sure that the incidence is correct and that they're set even...

Dynam DC3. Unofficial Unboxing.

...retro rocks

I'd been looking forward to taking a peek at the Dynam DC3 and pulling it out of the box certainly didn't disappoint.

The kit, the PNP version in this case, comes very well packaged inside a picturebox. Inside, the wings and fuselage are separately boxed, with all items also individually bagged. So, full marks on packaging.

The EPO moulding of all parts is very good, although in some cases the moulding spur hadn't been removed flush to the surface, but this is a minor gripe.

The props and heavy-duty nut have been upgraded since the original ugly-slow-fly two-blade setup, and the Dak looks a million dollars for it. The Dynam-badged three-blade props look great, the only negative being they're not contra-handed although this may just add a bit of crabbing character to the DC3's flight characteristics.

The undercarriage is fixed - no fancy retracts here, so the Dak always flies with wheels down, but it looks sturdy and the mounting configuration to the wing looks robust.

The removable canopy is large, giving good access to battery and receiver location. It engages into the fuselage at the rear with twin magnets at the front and can be surprisingly awkward to remove so well do the magnets engage!

The mounting of the engine cowlings is a rather tenuous arrangement using double-sided tape, with light handling enough to knock one out of alignment. I think this requires improvement to make it durable so it's not a continuous annoyance...