After going through the oily routine of fueling up, priming, connecting
the life support cable and spinning up the starter motor, I carefully
carried the buzzing Ripmax Gambler over to the flight line, and set
it down onto the grass runway. Hoping the little OS40LA motor would
not stall, I prepared myself for takeoff.
Sitting just ahead was a interesting looking plane, about to gun the
motor. From memory it was something like a Limbo Dancer, or a Panic.
I cast an eye over the brightly coloured plane, and in a way that is
difficult to describe, it looked purposeful. Whilst admiring this machine,
it was then that I noticed that his motor had stopped. I held back,
waiting for him to step out and collect it from the runway so I could
proceed. But he did not. Instead the prop whisked itself up into a frenzy
and dragged the plane upward into the blue yonder.
I was impressed to say the least. Obviously electric - but what a performance.
first RC plane, about 9 years ago, was an electric glider. It clawed
it’s way up, puffing away on a brushed 540 motor and 6 Nicad cells.
Sometimes only level flight was possible from a hand throw, and that
kind of fun does not last very long. Hence, I’ve been flying glow
motor planes ever since, but clearly, as this plane demonstrated, significant
developments have been made in the electric flight arena whilst I wasn’t
I don’t remember my own flights that day, but as I wiped away
the oil and grime using my scented baby wipes, I pictured this guy just
landing, slotting it into the car, and going home to the hanger; pristine
and ready for the next time. Looking back, it was then that something
sort of clicked.
It was clearly possible to fly sizeable airplanes on electric power.
The attractions were thus. The motor would start first time every time,
it would not stall in flight, the model would come down clean, it did
not need all the glow motor paraphernalia to start, and it had the added
benefit of being quiet. Being an Acoustics Engineer living in a noise
sensitive World, this feature was particularly appealing. In fact I
remembered that there are no timing restrictions for electric planes
at our site. Great!
of a new project
So, I set myself a brief, did my research, trawled the internet, set
up big Excel spreadsheets, and started buying Quiet and Electric Flight
magazine, a dedicated electric (and gliding) flying magazine. What I
wanted was to build a plane from a kit (that narrows things down a bit!),
a plane that was very slow and basic so that I could learn the characteristics
of the brushless electric flight system without trying to master another
plane as well, and finally something that had a bit of charm.
To cut a long story short, I narrowed it down to either the Junior 60,
a vintage dihedral high wing plane with rudder and elevator, or the
Piper Cub. The Junior 60 won out, and the build commenced. It took about
8 weeks to complete, and being tight I decided to try it out with parts
I had around me - an old buggy motor of fairly hot wind (16 triple I
think), hooked up to a 3:1 gearbox with power from 8 SubC Sanyo Nicads
of 1600mAh capacity that I had bought many years ago in an attempt to
boost the performance of the afore mentioned electric glider. I flew
the 60 that same day, and in essence it was nearly a total disaster.
I did get the plane home in one piece, but the flights (or controlled
crashes) clearly needed working on. In short I needed more power and
more rudder area.
For legal reasons (!) and to be fair to Ben Buckle kits, this plane
was originally designed for free-flight, then later it was used with
a small diesel engine to putter around the sky on calm evenings. I,
on the other hand, was flying it in a stiff breeze, off fairly long
grass, and with insufficient power, all of which was entirely my own
fault. I also found out that there was an electric version available
which would have made life easier than converting the diesel kit!
to the drawing board
So, the plane was grounded, and much time passed with other jobs around
the house being carried out instead. I gemmed up some more on brushless
technology, Lipos, and the like, and before long it was time to open
the wallet! I had heard good things about John Emms at Puffin Models
so gave him a call. He recommended a Mega 20/30/3E brushless motor,
coupled with a Jeti 40 advanced brushless controller and a maximum of
12x6 prop. As long as my existing 8 cell SubC Nicad pack was in good
order it would be sufficient.
Parts duly ordered, I then set about enlarging the rudder area. I did
this by fixing a piece of card to the fin and drawing around it. I then
removed the card and sketched a rudder with about twice the area (mainly
stretching rearward, but also vertically to try to keep the thing looking
proportioned). I was also keen to keep it lightweight, being at the
tail end of the plane. The originally rudder was a solid sheet, so I
cut most of it away, keeping a hinged vertical strip into which I tenoned
in some horizontal rearward pointing strips in the same style as the
fin, keeping the whole thing looking homogenous. I figured that replacing
a solid small rudder with a built up larger rudder would negate most
of the weight gain. This process turned out to be quite tricky as it
all had to be grafted onto the rest of airplane, rather than making
parts on a flat plan.
to the patch
With all shiny new parts duly installed, it was off to the patch again.
This time, however, things were different. Oh, there was still a stiff
breeze, which grabbed the right wing on take off and cartwheeled the
little plane off to the left on the first attempt, but I was determined.
I picked her up, went back to the start, and waited for a lull in the
wind. I waited and waited and waited, then suddenly there was a drop.
Right, here we go. It was obvious there was plenty of power this time
round, and I had also noticed that a bit of right rudder was needed
to keep her straight; a resultant combination of gunning the motor,
more wash from the much larger prop, and double the rudder area for
the wash to twist into. I made a mental note to add some right side
thrust to the initially straight ahead installation.
Due to the strong headwind, and full throttle antics, she was airborne
in less than 5 meters. With no elevator input on my part, she was climbing
strongly at about 30 degrees. I backed off the throttle – and
the nose gently dropped. Catching this slightly on the elevator and
adding some power back in again allowed me to steady the ship for the
first turn. This was uneventful and felt just right. Doubling the rudder
area had given me the perfect amount of authority, and with 50% expo
dialed in I was turning comfortably this time round. The next few circuits
were a bit up and down to be honest, as applying even small amounts
of power would make her pitch up noticeably, and backing off would drop
the nose again. I made another mental note to add some downthrust, along
with the right side thrust already noted. I also thought about moving
the C of G forward a bit because the glide was neutral / a little nose
It was soon time for a landing, and she came in fairly well, but despite
full elevator for the flair out, it basically didn’t happen. I
made another note to double the area of the elevator as well, to match
the larger rudder. I could already sense the hostilities should any
traditionalist one get a good look at the deviations I was planning.
Going through my mental notes, the motor was raised slightly and downthrust
added, together with some right side thrust. I don’t have an accurate
figure but it can’t have been more than a few degrees for each
axis. I then set about enlarging the elevator. In the kit this is a
solid piece of balsa, so I cut a lot of it away, leaving a long strip
still glued to the mylar hinges. Into this strip I cut some mortice
slots, and tenoned horizontal balsa strips rearward, finishing off with
a trailing edge piece to complete the built up elevators. All of this
build work was done on the plane, using a flat surface underneath to
keep the structure flat. With these modified feathers I found that I
had added hardly any weight to the tail end, which I was pleased about.
She was ready for another outing, so it was off to the strip.
This time I had a bit of an audience. It was a still warm evening, and
I was not alone in thinking I could sneak in a week-night flying slot.
Slightly nervous due to the bumpy flights I’d had so far, I placed
her on the strip and prepared myself for the flight. This time I new
there was plenty of power. I also knew I had enough authority, and that
the thrust lines were more favourable. So I opted for a more graceful
takeoff, slowly sliding the throttle forward to about ¾, and
waiting for the speed to build. A few moments passed, with very little
rudder correction required this time, until she nosed up into the air.
Much more satisfactory!
After a few settling circuits, playing with the trims incessantly to
find the optimum setting, I set up a low and slow pass down the strip,
right past my eye line. There is something wonderful about that moment
when a collection of wood and electronics, assembled together into a
certain order, magically defies gravity and hangs in the air, just there.
With the transparent film covering it was possible to see all the structure,
the electronic bits, and through the generous side windows I could make
out the pilot. Ok, so he was marginally the wrong scale, and probably
wondering why he was in a vintage plane rather than a jet, but still,
I’m sure he was just glad to be flying - as was I.
The enlarged rudder and elevator were giving me perfect control, and
at about ½ to ¾ throttle she held a fairly constant height.
This plane turns beautifully, and since everything happens quite slowly,
it quickly settles into a relaxing and restful experience. I heard a
few complimentary murmurs from those behind me in the pits, and as I
found out later, almost everyone gathered there had a Junior 60 tucked
away somewhere. Had I started a local renaissance?
Barely 5 minutes had passed and it was time to land. Not because of
the battery, but because it was getting late. My intention had been
to get some air under the wheels, and prove to myself that it was almost
There never seemed to be a decent weather window, so, being the impatient
type I eventually went out into another stiff breeze and slightly overcast
sky. The upwind leg was slow but sure, followed by a whisked away downwind
leg – but the plane really needed a calm warm evening to get it
into a nice slow groove. Idly running this thought through my mind I
turned downwind and opening the throttle. The response was somewhat
muted - had the battery gone already? It had only been 3, 4 or come
to think of it probably 10 minutes of battling the wind. Yes, I probably
had run it just one lap too far, and was now tasked with bringing it
down at the end of the strip, into the strong wind with a definite ‘I’m
landing now!’ glide angle. With a slightly early flair, and a
hop skip and jump, she was down.
Well, I’ve learnt a lot about electric flight since this conversion
a few years ago, with several successful own design planes to my name.
Who knows, I may write a bit about the development of these too.