air space
is the page for your articles - kit and equipment reviews, show reports, model flying tales both serious and amusing, nostalgia - in fact, anything at all that is likely to be of interest to fellow enthusiasts in the model flying world.


Record breaking in the Sixties

Barrie Pursloe

I started flying in the late fifties with a ground-based transmitter, single channel, valves and dry batteries. Flights were invariably short (sometimes extremely short!). By the early sixties we had progressed to hand-held transmitters and transistors had begun to appear. This progress made longer flights more feasible, limited now by engine duration. However, at about this time we "discovered" slope soaring. With this "new" form of flight, given a suitable slope and a fair wind, duration was only limited by battery life.

Click image for larger view

So it was that a group of Manchester based R/C flyers set about breaking the duration record for R/C slope soaring. The result is shown in the photograph, right - a certificate signed by Lord Brabazon of Tara no less!

The photograph, right, was taken as an official record of the flight. Note the strap over my shoulder from which was slung a lead acid motor cycle battery to power a transistorised inverter producing 135 volts D.C. thus doing away with the need for very expensive and short lived high tension dry batteries. Note also one of my mother's shopping bags which served as my toolbox.

The flight itself was pretty uneventful, well; thirty-four years on I certainly don't remember any serious problems. It was terminated by the wind slowly dying as evening came on; the trusty E.D. four channel (two function) reed set functioned just fine. The receiver was a "super regen." type and would pick up any transmitter in the 27 Meg band, hence we only flew one model at a time in those days. The model was an enlarged version of a published design (enlarged to carry the necessary weight of dry batteries) but, sadly, I have long since forgotten what it actually was. If any readers recognise it I would be pleased to hear from them.


... and a trip back in time for Pat Tritle

The first wood model I built was the Carl Goldberg Cessna 180 somewhere around 1958. And since modeling is really about nostalgia, I've had the urge to build another one of these little jewels for a very long time.

Meanwhile, my good friend Paul Bradley has been diligently reworking the plans and patterns from the old designs, and has now completed nearly the entire line of "Jig Time" kits designed by Carl Goldberg, as well as the free flight kits of the Cessna 180, Spirit of St. Louis, Shoestring and Ranger 21. All the these old models are available from Paul's web site (see site seeing) as free downloads, and are set up so that they can be printed on balsa sheets (if you have access to a flat bed or straight-through printer - more information on site seeing) so that the finished model is actually "painted" before it's built.

Anyhow, that opened the door to be able to build another of these nifty little models, which is exactly what I did. I built the model (above and right) from 1/20 balsa sheet, using the patterns in Paul's free downloads (PDF Files). The model was built using only the tools and materials that were used when the first one was built. Assembly was done using Ambroid wood glue, and all the "clamping" was done with masking tape. Cuts were made with a single edge razor blade, and the "paint work" done with felt tip marking pens. The only difference between this one and the original built from the kit was that this one was finish sanded.

All in all, this was a terrific exercise, and I definitely plan to do some others as well.

Coincidentally, Richard Cox also wrote re Paul Bradley's Carl Goldberg plans - see gallery.

In praise of autopilots

Idris Francis

In the article on his 2nd R/C Flight School which appeared on last month's air space, Greg Shane said " FMA's Co-Pilot is used continuously throughout the course. The Co-Pilot allows a student to correct his own mistakes, thus providing a stronger learning experience. During the early stages of training, the Co-Pilot's assistance is "high" and as the student becomes more comfortable the sensitivity is reduced and finally discontinued. The majority of experienced r/c pilots dislike the FMA Co-Pilot, because it makes the sticks "feel" strange."

Below, Idris demonstrates that autopilots are far more than just a training aid, and explains how best to use them.

I use the HAL autopilots on all my aircraft, except a few of the more recent ones which have the FMA Co-pilot, which I much prefer to the HAL since I found out that it exists.

The first thing to say is that it is not only possible but in my view virtually essential to use a spare channel to allow the autopilot to be switched on and off in flight - or MUCH better, to switch between 100% On, an adjustable mid range sensitivity and 100% OFF.

The first benefit of an autopilot is that it is an invaluable training aid - as Greg clearly accepts by using it - in that it provides as much built in stability as the pilot wants - including enormous stability at 100% sensitivity.

Want a Spitfire that flies like a Super 60 - or a model with anhedral that flies the same? Yessir - just turn up the sensitivity control.

Want the aicraft to be neutrally stable, or inherently unstable for maximum aerobatic ability? Yessir, switch if off.

Flying in gusty weather, and with a difficult landing approach? Switch on the autopilot, which deals with gusts FAR better than even the best pilot ever can.

Worried about the stability of the new own-design? Use an autopilot as insurance until you sort it out.

I accept of course that autopilots change the "feel" of the aeroplane - but that is irrelevant when, as you should be able to do, you can switch it off in flight. I fly some of the time with the autopilot at its mid range setting - which makes my neutrally stable CAP 232 fly like a modestly stable mildly aerobatic trainer - but when I want to do precise aerobatics I switch it off, e.g., to avoid the autopilot rolling the aicraft out of loops, or making sustained inverted flight impossible.

The FS8 Co-Pilot is the newest and most powerful addition to the FMA Flight System product line and offers flight stabilization and 'true failsafe' for any R/C aircraft configuration.

After several years of experiment, I have optmised my set up as follows:

A 3-position switch on the top left-hand side of the Tx, giving 100%, 50% and 0 % sensitivity. I normally take off and tooge around on 50% - especially in gusty weather- and switch if off for aerobatics, but (here is the IMPORTANT bit) with 100% extremely effective stabilisation and recovery from ANY attitude within a second or so, INSTANTLY available by pushing that switch to 100%. If I get blinded by the sun, attacked by someone else's aircraft on a low fly-by (WHY do they do it?), get disorientated for any reason, lose sight of the model due to low cloud or - again most importantly - in the event of loss of signal for ANY reason, the same 100% recovery and stability of ANY model.

Did not hear the Tx battery warning bleep? Aerial snapped on Tx or Rx? Out of range due to damaged Tx output stage after too many hours on a simulator with aerial retracted? A violent glitch that leaves you disoriented with the aircraft way down wind on a landing approach? How valuable is it to be able to hit that switch and 1 second later KNOW that the aircraft is flying straight and level, so that you can twitch the ailerons to confirm its direction?

For ALL of these reasons, what price a model that will fly itself, and quite possibly allow you to recover control instead of a pile of matchwood?

Incidentally - actually most importantly also - a throttle failsafe, and an instinctive response of slamming the throttle shut at the same time as hitting the 100% autopilot switch, so that you not only know the aicraft is flying straight and level but slowly - is essential. Indeed, in my view lifting off without a throttle failsafe, and indeed without a range check before the first flight of each session, is utterly irresponsible.

Incidentally, the integrated FMA Co-pilot, all in one, is tiny AND gives fail safe settings for ALL channels.

A nice model flying tale ...

Yesterday's Flying Session

narrated by Tony Whiteley

Last weekend I concocted a "head-cam" and filmed myself flying my new Picco-Z around my living room.

Watch Tony's video on You Tube by clicking the monitor icon.

My "head-cam" is simply a Canon Ixus50 which I fasten to my flying cap. The system is still very much in its infancy so is prone to "hit-and-miss" rates of success, but I will perfect it . . . . eventually!

But the main idea for "head-cam" was to film myself flying my normal RC models at the field. So yesterday afternoon (30th April) I headed over there to give it a try. It was a lovely warm day, but the wind was blowing at 20mph and gusting 25/26mph . . . . but I urgently needed to test "head-cam," so there was no way I was not going to fly.

Miss Funtana was soon in the air and the first flight went without a hitch - except that head-cam recorded only the ground I was standing on and not the model. I'd obviously got it aimed too low (I hadn't noticed that my home-made electrical-wire viewfinder had got bent during transit!). I re-fuelled, adjusted head-cam, and off we went again.

Everything was going really well, until - suddenly - I completely lost control of the model!

I'd just been showing head-cam how fast the model will roll (very, very fast indeed!), and then she suddenly stalled and dropped several feet. She was reasonably high when it happened, and I immediately knew something had gone seriously wrong because she wasn't moving across the sky slowly enough for this to be a "normal" stall.

At first I thought I'd lost all radio contact, but as soon as I opened the throttle the engine responded. She flew out of the stall ok but needed lots of control inputs to keep her wings level - and then she almost stalled a second, and a little later, a third time. By now I was guessing that I'd lost an aileron - and as it turned out I wasn't too far wide of the mark.

I quickly realised that a Funtana aileron adds up to a very large percentage of the wing itself, and that a non-aileron wing was therefore going to produce far less lift that a "good" wing (unlike many "normal" models, where the loss of one aileron can often make little difference to the handling).

My first thought was that I should keep the speed up in order to prevent further stalls. But I then discovered that too much speed meant that the amount and direction of rudder and aileron correction had to be changed constantly, making a difficult situation even more so. I was banging the sticks around as though I was stirring porridge - two bowls at a time - just to keep the model flying somewhere close to straight and level. It was round about now that I began thinking I may not be able to keep her in the air much longer, let alone actually pull off a landing.

I decreased the speed a little and the model seemed to settle better, making the corrections a little easier to apply and allowing me to "nurse" her in a little closer. Then I spotted what had really gone wrong. The starboard aileron had become almost completely detached (remember those "really" fast rolls ... maybe they were just a tad "too" fast!). The aileron was flapping around in the slipstream as though it was a rag tied to the centre of the starboard wing's trailing edge. And it was sort of rotating first one way and then the other way in the slipstream. One second it would be adding to the lift, and then the next second it would be acting like a massive air-brake, then a flaperon, etc. No wonder this thing had suddenly become rather difficult to fly, I thought.

The landing was definitely not going to be easy. But I got her lined up and worked at the controls to keep the wings as level as I could, whilst also working at trying to prevent another stall, or a dive, or a sudden prop-hang - it was all "trying" to happen. Then it all got just a little easier - I had started to become accustomed to the new flight characteristics (gulp!).

But that starboard aileron kept on flipping around, so I was still constantly having to switch from left rudder and aileron to right rudder and aileron as well as from up to down elevator - and every combination thereof. The impending landing was now looking decidedly "iffy" - and then I had a flash of inspiration - maybe I could arrange it so that the crash would be fairly close-by to save myself a lot of walking afterwards. But it was impossible to steer the model closer towards me as well as deal with everything else that was happening.

As the model descended towards the ground I allowed the speed to decay just a little, and right then the aileron decided to stay in one position instead of "windmilling-around" (what a relief!). The landing itself was actually successful, even though it required right aileron, right rudder and down elevator right down to the ground. It was a poor landing really, as it was heavy and it bounced! But at least it was down without having suffered any further damage.

So what had actually gone wrong?

The starboard aileron was only held in-place by one single, central, hinge - plus the (also central) servo push-rod. The other three hinges had sheared along their centre-line between the aileron and trailing-edge of the wing. No wonder the model was difficult to fly with this enormous control surface continually changing its angle of attack, etc.

What do you think? Was I lucky yesterday, or was I really-really-really lucky yesterday?

And before you ask me: yes I will be fitting tougher hinges sometime soon, and yes I did get the landing on video. But the quality of the video isn't good at all (I'm still "perfecting" how to use my head-cam). The model looks like a white dot in the sky unless it happens to be really close to the camera - and I couldn't fly this model that close-in due to the high winds and whilst I was sighting it in my head-cam viewfinder too. But here's the link to what I got of the landing anyway:

- click the icon to view the video.

If you view the video, please excuse the expletives. I just don't know what prompted them!