Shaun Garrity looks back to early R/C helicopters.
This time in Retro Ramblings we have something a little different – retro helicopters. It’s hard to believe it was the early 1970s when I first came across them (I suddenly feel really old). R/C helicopters were actually flying prior to this but they were mostly constructed by pioneering modellers having to figure things out for themselves, because as far as I know no commercial products were available.
Dieter Schlüter was one such pioneer from the late 1960s and he can essentially be considered the father of modern R/C helicopters; he actually won the first R/C heli competition held in Harsewinkle, Germany in September 1968.Article continues below…
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However, the first R/C heli that I am aware of was developed much earlier by Lockheed in 1958. Powered by a McCoy 60 and controlled via an eight-channel reed set it used a mechanical flybarless gyro. Not designed to hover, it was just a proof of concept to establish if it would be stable and controllable in forward flight. It did fly on numerous occasions and land in one piece, but little information was made available at the time. I guess they saw commercial potential in the venture and didn’t want anybody pinching their ideas.
Adesign for a scale Sikorsky S-64 Hexi-Copter by Ken Norris was published in Flying Model in the early 1960s and at 99” rotor span it was almost unbelievably powered by two Cox 049 Thermal Hopper engines driving the rotors round (a sort of big boys McCutchen wing affair) with an electric motor for the tail. It was massively complex and needed well above average engineering and lathe skills to construct. I’m not sure if it ever flew successfully as it was intended as a proof of concept but certainly garnered massive interest in the modelling community at the time.
The 1969/70 Aeromodeller Annual featured a thirteen-page article by Dieter Schlüter packed with useful information for the budding builder/pilot. And like the film ‘Those Magnificent Men in their Flying Machines’ some truly weird and wonderful designs were detailed.Article continues below…
The start of the new decade, 1970, was the year when what can be considered the first successful R/C heli kit appeared on the market. It was the Bell Huey Cobra by Dieter and it was extensively demonstrated in the USA and Europe. It also had the honour of being the first heli reviewed in a UK hobby mag, Radio Modeller, January 1973.
A number of other manufacturers were ‘hot on his heels’, as they saw this new branch of the hobby being potentially very lucrative. But only Kalt in Japan brought a kit to market, the Cobra 450. In 1973 Jim Morley started selling his Bell 47 and Peter Valentine’s Lark made its debut on the circuit but was not yet available as a kit.
In 1974, Peter had done a deal with Micro Mouldand the ubiquitous Lark exploded on the scene. This was my first heli and I actually managed to get air between the skids and mother earth on many occasions, with damage free landings. It all started going wrong when I tried circuits but that’s another story.Article continues below…
Things started accelerating from this point, with offerings from Graupner, Hirobo and Kavan to name but a few. Kavan also had a first by designing the first commercially available electro/mechanical gyro but it was very expensive and required soldering into the tail rotor’s servo internal wiring. Get it wrong and you had a costly paper weight. In 1979 Futaba brought out a heli specific transmitter, with bespoke mixers and switch functions. The first inverted flight was demonstrated at the Graupner Challenge Cup, Lausanne, Switzerland by Ulrich Baudrexel in the same year, using a reversing switch on the Tx. However, Mike Mas from the USA had the honour of being the first pilot to fly continuous inverted flight from a non-switched Tx, just like we do today.
And this brings me nicely to an email received from modelling pal, Pete Christy, a lifelong model helicopter enthusiast, and well-known radio control and electronic widget designer.
Pete On PeterArticle continues below…
“It was late in 1973 when I first stumbled across Peter Valentine and his ‘Mayfly’ helicopter. Work had taken me to London from my hometown in Devon and I’d joined the Watford Wayfarers Model Club.
Shortly before leaving Devon some of the model flyers in Plymouth had banded together and bought a job lot of Schluter ‘Cobra’ helicopters – not only the first successful model helicopter, but also the first to become commercially available. The Cobra was (and still is) HUGE! The fuselage alone is over six feet long! Expert wisdom at the time was that it would not be possible to build a model helicopter that was any smaller. You can therefore imagine my surprise on turning up at the Watford flying field one day and finding some chap flying a tiny helicopter powered by an OS 10 (1.5cc). It flew extremely well and was smaller than a single rotor-blade on a Cobra.
The builder/pilot was Peter Valentine. I knew him by reputation, having seen pictures of his futuristic ‘Firebird’ fixed-wing designs in the magazines, but this was the first time I had met him. He told me that his first successful helicopter, the ‘Lark’, was being prepared for mass production by Micro Mold and that they were hoping to get it into the shops for a third of the price of the Cobra and its rivals! Sure enough, about 12 months later, ‘Larks’ appeared on the shelves and sold like hot cakes. In truth, it was a very simple machine; some would say crude and it wasn’t the easiest to fly. But what it lacked in sophistication it more than made up for in its price and ruggedness. I witnessed novice pilots tip them over, straighten the bent rotor-shaft with their bare hands and carry on flying, albeit with a bit more vibration. A rotor shaft cost 75p; a Cobra rotor shaft was £12. No wonder they sold so well.
Peter later told me that he had wanted to buy a Cobra when they first came out but discovered that for the same money, he could buy a new Myford lathe. He decided to buy the lathe, taught himself to use it and proceeded to design and build over thirty helicopters with it – money well spent.
Peter was also an excellent draughtsman. All his radio equipment was home-made, albeit based on published designs. When I started designing my own radio gear, later produced by Mick Wilshere as the ‘Talisman’ radios, he asked for the circuits and managed to shrink them down to a size I could never achieve. I thought I had done well to get a 459MHz receiver into the same size box as Mick’s 27 MHz receivers, but once Peter Valentine got hold of it, he managed to make it even smaller.”
“Peter was a great experimenter and never made two helicopters the same. The Mayfly series of helicopters was an attempt to produce an even smaller model than the Lark and eventually he managed to produce a miniscule one powered by a Cox .049. As well as the original OS 10 powered Mayfly seen in the photo, he made a version with a three-bladed head. Unfortunately, it proved to be too stable. It would sit there in the hover and as soon as a control was applied the rotor-head would counteract it. All that happened was the model would wobble a bit and continue to sit there in a perfectly stable hover.
He also attempted an electric version. This is long before the days of brushless motors and LiPo batteries. The Mayfly-5 was his 15th design but it never flew, the weight of the battery pack proving too much for the geared, brushed motor.
Sadly, Peter Valentine passed away some years ago and I helped his family to clear his house. Whilst doing so, I stumbled across the Mayfly-5, and asked if I could keep it. The family readily agreed. The Mayfly-5 sat in my attic for a number of years but on a recent visit my son asked if I was ever going to do anything with it, so we dragged it out of its resting place and had a look. Peter never built two models the same. There was always something different about each one. The Mayfly-5 had a very interesting tail-rotor gearbox (to put it mildly).
Initially we tried just fitting a 3S LiPo and seeing what would happen. The model was seriously over-powered with this setup and was airborne at about 1/4 throttle. We reduced the pitch on the main blades and tried again. At this point disaster nearly struck. The speed controller couldn’t handle the power and went short-circuit. The heli went to full throttle and the radio froze. Luckily, I hadn’t fitted the canopy for these trials and the model crashed into a nearby hedge. The magic smoke came out of the speed controller as I frantically tried to disconnect the battery! By some miracle, aside from the burned-out ESC, the model was undamaged. I did manage to find another ESC that a chap on another forum reckoned would handle a 3S LiPo, but I decided not to risk it and go for a full brushless setup.
The first motor I tried nearly worked – it got light on the skids but never got into a hover. From that trial I worked out that I needed a motor of around 350 watts, and 2200 to 2700kV. Unfortunately, every motor of this size seemed to be out-of-stock at the time. Eventually I located a 3000kV 615-watt motor that looked as if it should fit, so I decided to give it a try. I made a fairly crude motor mount and needed to source a shorter toothed belt for the drive. I had already converted a Lark to electric power very successfully and had a supply of 10-tooth pulleys to hand from that. This combination proved to be instantly successful and the model was airborne at half throttle. The cyclic response was very slow, and it felt somewhat tail-heavy, but it was FLYING. It just goes to show what a clever guy Peter Valentine really was.
Unfortunately, following some further test hops, the ‘experimental’ tail rotor gearbox has turned out to be a dud, with the gears failing (melting) in flight. Luckily, I was able to get the model down without any further damage; it wasn’t very high. I had a trawl through the boxes of bits I inherited when Peter passed away and found enough bits to build a new tail-rotor gearbox for it. This comprises an experimental Lark gearbox, to which I’ve added the pitch control mechanism and hub assembly from the original Mayfly gearbox. This new gearbox is lighter than the original, which helps with the tail-heaviness, but introduces some problems of its own.
Like the Lark it was designed for 1/8” shafts, but the Mayfly used 3/16”. Luckily my old flying buddy, Geoff Bell has a very well-equipped mechanical workshop and he was able to make me some special shafts to solve the problem. The new gearbox switches the tail rotor onto the starboard side but keeps the rotation the same. The change in position of the tail-rotor has required some re-routing of the driveshaft and pitch linkage but this has been fairly trivial to achieve. However, for some reason, although the various bits all moved smoothly and easily on their own, when coupled together it all got a bit sticky. I eventually traced the problem to the plate that holds the plastic ball joints being too rigid; it didn’t have any flex to allow for the rotation of the blade grips. It was aggravated by the fact that I’d had to replace the ball joints with modern ones, which were much stiffer. I replaced the aluminium plate with some thin fibreglass printed circuit board. This gave an immediate improvement in the smoothness of the linkage, as well as helping with the tail rotor trim.
Test hops continue. At the time of writing, I’ve managed several prolonged hovers in my garden, but poor weather has prevented me from doing anything more adventurous. As soon as I get a calm day, I’ll fly it around a bit.
Whilst searching through Peter Valentine’s box of ‘experiments’, I found the chassis and central mechanics for another .049 powered Mayfly. The original was donated to the Goosedale Model Flying Museum. I also found the remains of his ‘Wasp’ helicopter, intended for a Cox .020. Sadly, this too never flew, largely because of the difficulty in producing a working clutch at such a small size. Years before flybar-less helicopters became the norm Peter converted a Lark to flybarless operation with no electronic stabilisation. I copied his modifications and still fly mine like that from time to time! He was also keen on trying to use the new-fangled tail-rotor gyros to stabilise the main rotors. Sadly, the mechanical gyros available back then, combined with the relatively slow servos of the era, made it impractical, but it shows how far ahead of his time he was.
Peter Valentine was a man of many talents. The Lark helicopter introduced a lot of people to the art of flying model helicopters in the 70s and early 80s. His contribution to the model helicopter scene deserves to be remembered.”
Veron Impala, Devolved
Fellow modellers often ask me why do I do it; take a perfectly good propo controlled plane and install single channel gear? Well in this case the Impala was my first successful R/C model, flown with MacGregor single channel gear and a rubber powered escapement giving full left, full right and kick down elevator. I had hours of fun on the slope and occasionally I was guilty of annoying golfers on the green below, who alleged they could hear the model ‘clacking’ as the escapement functioned. I even became known to one or two bus drivers, whose chariots I would frequent to get to the slopes as I was far too young to legally drive. I suppose they rarely if at all saw youngsters getting on board with a 52” wingspan model plane.
I still get a great buzz from flying planes with this rudimentary control system, especially when propo modellers have wimped out because it’s ‘too windy’!And did I mention that it’s ‘loads of fun’?
I had a tiny problem though; my Impala was built for me by my dear departed friend Phil Smith, who was the chief designer for most of the Veron model range, and I am a little precious about it. Knowing this, my buddy Phil Green donated an old and well flown Impala for single channel use. It hardly made a dent in his fleet; I believe he has half a dozen of them, but it was gratefully received. After a day’s fettling and recovering it’s now looking resplendent in the same colour scheme as my original, with the exception of the vinyl cut decals.
In the early days of my 2.4g transmitter conversions, I updated an OS Pixie and MacGregor Codamac using Phil Green’s single channel encoders. As I initially got a little carried away with conversions and had more than I really needed, these had been languishing in the hobby room unused for years, so it was time to fix that. Another converted and unused Tx was a Waltron 2+1 that gave proportional rudder and elevator and three position throttle. This too had been updated to 2.4g but has recently been upupdated (is that a word?) using a brand-new encoder that Phil has developed. It’s hard to believe the postage sized circuit board has far more functionality than the original PCB that was the full width of the Tx. Anyway, I now have three options for flying the Impala as they all use the same RF modules: old school on the button, single channel emulation giving left, right and down with the OS Pixie, and same again with the MacGregor except it had a built in coder stick so you didn’t need to have multiple button presses to achieve, left, right and down, and propo with the Waltron if I want to let other modellers fly who are not conversant with the ancient art of single channel. Hopefully it will no longer annoy any golfers – servos shouldn’t be noisy!
Stay safe and keep sending in your stories, photos etc. to: firstname.lastname@example.org