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"Non-stop indoor flying with a fascinating model that anyone can fly... The 'Hoverfly' is a fantastic little machine, which will give hours of fun to anyone that buys it." Iain Erskine reviews Hoverfly in Model Helicopter World, a leading UK enthusiasts' magazine. October 2001.

What Is It?
The 'Hoverfly' is a British made electric powered helicopter, which is almost ready to fly straight out of the box. It is designed mainly for indoors flying, although it could be flown outside on a very calm dry day. The 'Hoverfly' is currently available in two forms i.e. the H100 and H101. The only difference between the two is that the H101 is fitted with a tiny solid state gyro. The extra £30 that it costs is well worthwhile to get the benefits of the gyro.

What's In The Box
The box that contains the 'Hoverfly' is quite small compared to those that we helicopter flyers are used to, being about the size that you would expect to receive a canopy in. It's very colourful, with various pictures of the 'Hoverfly' and descriptions on it. On opening the box one finds that it contains a recessed polystyrene moulding similar to a radio set box. This more than adequately protects the 'Hoverfly' itself, and the various other components. The rest of the kit includes; a mains transformer (which provides 35V D.C. to the helicopter), two leads for connection to Futaba or JR transmitters, an Electrocyclic Control Processor (the clever bit - the brains), a training undercarriage, decals, trim lines, accessories and an excellent instruction book. The only additional piece of equipment required is a transmitter with a minimum of four channels, a training socket and servo reverse on all functions. A helicopter set is not required (but can obviously be used), but whatever transmitter is used, it must be set or programmed to PPM (FM).

History Of The 'Hoverfly'
The designer of the 'Hoverfly' is a very nice chap called Phil Jermyn. He and his buddy Roderick Snell decided that the 'Huffily' would be a viable product and together they put it onto the market. In all it has taken around four year's work to get the 'Hoverfly' into its present production. Both Phil and Roderick decided, right from the outset, that they wanted the 'Hoverfly' to be as perfect as it could be. When they thought it was right, they then put a number of pre-production kits out to various flyers and got them to thoroughly test them. The important thing is that they then listened to the feedback and acted on it, which has resulted in a very good product, which does exactly as one would expect. The other thing that Phil and Roderick have done is put the 'Hoverfly' on the market at a price that I think is just right and represents excellent value for money. The 'Hoverfly' has been around for around two years now and the latest version, the 'Hoverfly II' has just been put onto the market. Improvements over the first version include a new rotor system which does not require covering and has improved propeller; a smaller power unit, which is a considerable 1,080 g lighter than the earlier version, which cuts down postage costs drastically; improved electronics, making it easier for beginners to fly; improved tail control with a long-lasting drive belt; a wider undercarriage which will help the beginner; a new instruction manual (the old one was quite good anyway) and a ready printed window (the older version had a separate one which needed to be glued on).

The Hoverfly
The 'Hoverfly' itself is a work of art and ingenuity. It is a proper remote controlled helicopter with the main difference being that it has an umbilical cord, which carries both the power and the signal to the helicopter. There is no radio transmission and no batteries to charge or fuel to burn. The helicopter is incredibly light, having a rotor diameter of 12" and I weighed mine at 2.4 ounces (68 g). It has a very light frame and thin wire undercarriage. The frame carries a tailboom (like a large straw!), gyro and electric motor to drive the tail, which is belt (more like a thread!) - driven. A tiny gyro is fitted between the frames of the H101. The canopy is made of A.B.S. and looks not unlike a Robinson R22. Basically the machine is ready to fly. It only needs finished off using the supplied trim lines.

How Does It Work?
The machine is powered by an umbilical chord, which is made of several strands of wire. This provides the electrical current to the tail and main rotor, along with the control commands. The supplied chord is some 3.5 metres long and quite flexible, though care is required to ensure that it does not get kinked, and a storage reel is included in the kit, which helps. The really interesting bit is the rotor head. This has three spars, which look like blades, but are not actually designed to give lift. These are now covered in plastic tubes, the first version required covering with film. Each of these rotor spars has a small electric motor on the end, which drive a two-bladed propeller. The motors point upward and about 5° off the vertical. Because of this offset thrust, apart from providing lift, they cause the rotor to turn, which allows the unique control system to come into effect. The rotor only spins at around 250 rpm. Collective control is supplied by giving the same amount of current/thrust to all of the motors at the same time. Cyclic control is supplied by giving varying amounts of current as the motors rotate. This is provided through the rotor hub. The design of rotor head means that there is no torque reaction (which would require the tail rotor to be driven all the time) and this results in a very stable machine. The tail rotor itself has a pre-set fixed pitch and current to a small electric motor supplies tail control, which simply reverses for right and left. All the control and power inputs are controlled by the ECP, which takes the power from the transformer and the signal from the radio set and puts them through to the 'Hoverfly' via the umbilical chord. The ECP does away with the need for a receiver, servos and switch, making a considerable saving on normal models.

Getting Started
Before taking any of the components out of the box the first thing I would advise any new 'Hoverfly owner' to do is read the instructions thoroughly and then read them again! A lot of thought has gone into these and they are first class. They give all the information that anyone could need. The 'Hoverfly', although very robust should only be handled by supporting it by the rotor hub, nowhere else, including the dome cap, which can easily be pulled off. The canopy itself sits in place over sponge tape, which provides an adequate damped mounting around the main frame and the tail electric motor. Very thin decals and two sets of trim line (one red and one white) are supplied for a personal finish. The rotor assembly is jig built and the small propellers are a matched set, which should result in an already balanced head. Things to check when taking the 'Hoverfly' out for its first flight is that the undercarriage is pushed fully home, the umbilical chord is not twisted or kinked and that the canopy is true on the sponge. Another thing that must be checked is that the tail boom is fully home. It sits in rubber grommets which push home onto the main frame. It should also be checked that the fin is vertical and that the propellers are pushed onto the motors properly. The propellers are just a press fit onto the electric motor shafts. The machine is well finished on being sent out and I suggest these checks used as a precautionary measure, before first flights and after any 'incidents'.

Setting Up
Once the 'Hoverfly' is checked out, the next thing to do is to work out the radio setting. There is a board inside the E.C.P., which has various wire links to set up the unit for different transmitters. It comes ready set up for Futaba type transmitters and the instructions are quite clear on how to set up the unit for almost every other type of transmitter. You should then set up your transmitter according to the instructions. As the 'Hoverfly' only requires the first four channels, there is no need for setting it up with special 'helicopter' functions, a standard aero set-up will do. The next thing to do is to identify the lead for your set and connect it to the transmitter and the ECP. You then connect everything up, EXCEPT the 'Hoverfly' to the ECP. The ECP is an amazing piece of electronics and contains no less than 263 components. You may need to switch your transmitter on, depending on what type it is. If you do, to prevent it transmitting you should remove the crystal from the RF unit, the 'Hoverfly' does not need a radio signal to work, it's transformer powered. This feature gives a tremendous amount of flying time from the transmitter because the TX Nicad is only powering the stick pot' circuitry. Having carefully removed the cover from the ECP, you can adjust the trim pot until two LED's go out and the neutral is set. During this operation, ensure that the trims, and both sticks, on the transmitter are at the neutral setting. Once this has been done all that is needed is to put the cover back on the ECP and switch everything off.

Flying
Now the radio has been set up it is a matter of getting everything ready for the first flight. Everything, including the 'Hoverfly', should be connected to the ECP, but it is vital at this point to ensure that the transformer is unplugged. Once everything is connected, the transmitter should be switched on (if it hasn't already come on with the signal lead being connected) and checked that the throttle stick is in the low position. The 'Hoverfly' should be supported at the rotor hub, just in case it starts on full power, although it shouldn't if you have set the radio up correctly. Whilst holding the model carefully, the transformer should be plugged in (and switched on) and everything should now be ready. The first thing to do is check that the tail goes the right way and that the gyro works correctly. If you are a total novice it is advisable to put the training undercarriage on. All the controls can now be checked by holding onto the 'Hoverfly' and gently running it up. I set the dual rates on my set at 60% on the cyclic controls after some experimentation, so if you have this facility, you may also want to try this yourself initially. I certainly found that this gave a nice gentle response.

The instructions give clear guidelines on your first flight on how to approach getting the 'Hoverfly' into the air. I had also been given the same advice from someone who had already flown one. One important difference between the new and old versions is that the gyro needs to be left for a minimum of three seconds to set itself up before lifting off. The secret of successful flying of the 'Hoverfly' is to raise the collective stick slowly until the small propellers start to drive the rotor. Let the rotor speed build up and raise the collective a bit more until the motor moves a bit faster. From here raise the collective to around 3/4 stick and the 'Hoverfly' should lift off. Lift it straight up into the air until it reaches a height of around 2 ft and then back off the throttle to maintain constant height. The 'Hoverfly' definitely does not like being near the floor in ground-effect and will either tilt over or go shooting across the floor into something.

Once it has been lifted to the height that I have just suggested you will find flying it very straightforward indeed. Once trimmed properly it will handle just like any other well set-up model. When the rotor is turning at the correct speed the electric motors and propellers 'disappear' and it looks like a tiny helicopter. The response from the controls is very instant and the electric motors pick up immediately on all four controls. It is fairly easy to over control the 'Hoverfly' in its first flights but don't get me wrong here- it is a very stable machine. However, it can move when you want it to! The tail is powerful too but the funny thing here is that with the lack of torque, the tail rotor stops very regularly and only comes on when the gyro senses a movement. It is a very easy machine to fly on just the cyclic controls alone and pirouettes are an absolute breeze. One thing that you also tend not to notice when it is flying is the umbilical chord. However, you should always remember that it is there, as it may catch on something. Also, remember that if you are doing pirouettes is to do them in equal numbers left and right to prevent the umbilical chord twisting. The 'Hoverfly' is so stable that I was able to do 720° pirouettes quite easily. Most standard manoeuvres can be done with the 'Hoverfly', circuits, pirouettes and nose-in, so it is certainly a very useful machine. The 'Hoverfly' has some amazing benefits. All my flying has been done in my living room in an area about 7' square, due to the furniture in it and it is not difficult at all to do all the manoeuvres that I mentioned in such a small area.

The one thing that does become very clear with the 'Hoverfly' is its survivability! My flying buddy Robert came over for a weekend's flying, and, as usual, he brought over the wind and rain with him! My 'Hoverfly' had arrived a few days before. Although I had some initial flights with it, it was about to get some real flying! Some three hours constant flying later, having been bounced off walls, windows, couch, chairs, me, my son Gordon (he said it didn't hurt at all) and various other objects it was still flying! All that needed to be done to it if it did crash was to line everything back up, check its integrity and lift it off again. The most common thing to come off the 'Hoverfly' is the propellers. Because they spin, they tend to brush against any object that the 'Hoverfly' is going to hit and they absorb most of the impact before coming off. Due to the fact that the rotor is only doing around 250 rpm and the electric motors are gripped in a plastic mount, very little damage is likely to be caused. The only damage that I have done in my living room is a small nick in one of our lampshades. Don't be confused by this slow rotor speed as I was, for once the cameras lie! I had seen pictures of a 'Hoverfly' and I thought that the rotors were still and the electric motors were fixed, this is not the case as the camera flash 'stops' the movement. Robert flew the 'Hoverfly' into me quite hard when the chord caught on one of my trainers and all it caused was a very slight scratch. The 'Hoverfly' just instils confidence in the pilot when you know that you have little chance of damaging it. Its size also does not intimidate you.

During most of my flying sessions with the 'Hoverfly' my wife has remained in the room and she is generally fairly wary of model helicopters. Even our two Chinchillas, 'Smokey' and 'Bandit' enjoyed watching the 'Hoverfly' buzzing around our living room! Having said that it is possible to cause injury with anything and care should be taken to prevent this, although I think that it would be very difficult to cause serious damage with the 'Hoverfly'. Mine has had over 15 hours flying now and the only things that I have had to replace on it have been the propellers and a tail belt (it is well worthwhile having spare sets of these from the start). The only other thing worthy of mention in regards to maintenance is that in a heavy crash the electric motors can come loose. This is simply cured by checking the integrity of the rotor spars and, if necessary, gluing the mounts back on with cyano. You should check these after each heavy incident, as it is not nice when they detach from the spars in the air!

Don't be put off by the appearance that I am not enjoying myself with the 'Hoverfly' in the photographs - it is pure concentration as the amount of room was reduced even more with my son Gordon trying to take the photographs. Remember, the 'Hoverfly' is really small and yes, he was that close (shows he had confidence in me, or was it the 'Hoverfly'?!!). I have had the advantage of flying both versions of the 'Hoverfly' and would have to say that I found that the latest version performs slightly better than the original, that is not to say that there was anything wrong with the original, but as we experience with most radio controlled helicopters updates by manufacturers do make a difference. It is good to see 'Snelflight' taking a keen interest in the 'Hoverfly' and keeping it as good as they can get it. I initially took the latest version straight out of the box, set it up in a few minutes and flew it without any trim requirements.

Conclusion
So what do I think of the 'Hoverfly'? In one word: 'fun' with a capital 'F'. The 'Hoverfly' has been very cleverly designed to get into the air in the least possible time, with the least effort and cause the least amount of downtime after crashes. On that point, the price of spares is ridiculously cheap so it won't break the bank. It has a hell of a lot going for it. It flies well straight out of the box. You don't need a special helicopter radio set to fly it. You can fly it in a very confined space. It is very quiet; it sounds just like a 'Hoverfly' buzzing around. You don't need to charge batteries or deal with fuel. It can be flown if it is dark or wet outside. It will carry out most manoeuvres and will allow practise with things like nose-in and pirouettes. It does not instil 'fear' in the pilot. It keeps 'bouncing back for more' and has real survivability. It is very reasonably priced to start with and has very reasonably priced spare parts. I wouldn't like to see the 'Hoverfly' classed as a toy. It is a complicated flying machine in its own right and deserves high praise. A lot of thought and work has gone into its design and getting it onto the market

$64.000 Question!
The one thing that I would imagine that most people would be thinking is, would I consider the 'Hoverfly' suitable for beginners. I would have to say 'yes' in response to that. Firstly, once the 'Hoverfly' is safely off the ground it is a stable machine, although like all model helicopters it does not 'fly itself'. The first problem that a beginner would find is getting the 'Hoverfly' into the hover in the first place as this takes a bit of work and this would be my only reservation. I am aware of one young lad who taught himself to fly on a 'Hoverfly' and went on to successfully fly a radio controlled model helicopter. Secondly, the cost of the 'Hoverfly' is extremely reasonable, at around £180 for the H101 (including gyro), making it extremely attractive to beginners. Obviously, as they progress, they would have to consider spending more cash on a radio-controlled helicopter and suitable radio gear. The cost of spares and the lack of 'fear' of the machine would also help the beginner, as this would instil confidence. The survivability of the 'Hoverfly' is something else that I would consider to be of real benefit to the beginner. All he would have to do after most crashes would be to straighten it out and get on with flying, no hours of repair work, or serious dents in the wallet. The one thing that has really said it all for me in this aspect is that my wife Dorothy wants to have a shot of my 'Hoverfly'. My son Gordon has had a go with it and managed quite well. Some of you will know that I consider computer simulators as ideal ways of learning to fly or learn new manoeuvres. The one thing that they do not do is give is an absolutely true (although very close) sense of flying a model helicopter, whereas the 'Hoverfly' does.

Happy Hovering.

Verdict
The 'Hoverfly' is a fantastic little machine, which will give hours of fun to anyone that buys it. It has a fair bit of competition at the moment with the introduction of the latest indoor electric helicopters. The 'Hoverfly has the advantage over these of firstly, the initial cost and secondly the fact that they can literally fly for hours, without the need ever to recharge it. The only disadvantage compared to these other electric models is the umbilical chord. It is currently only available through a few outlets, so check the modelling press.

PHOTO CAPTIONS
1 Ready to roll and fully decorated with the supplied trim-strip.
2 The box contents revealed (Mk. 1). This packaging is worth keeping for future travelling when visiting interested friends houses.
3 Rotorhead and canopy removed to reveal on-board electronics.
4 The 'black box' electronic control, unit which connects to the model, transmitter and mains powered transformer power supply.
5 "I've got a little model". Proving that size really doesn't matter!
6 The camera lies, those rotors are turning at 250 RPM!
7 You don't need a lot of space to fly it - the living room will do!

Quotes:
'it would be very difficult to cause serious damage with the 'Hoverfly'''
'The 'Hoverfly' just instils confidence in the pilot'
'fun' with a capital 'F'
 

"I am very impressed - the model may be unorthodox, but the handling characteristics realistically represent a conventional single rotor RC helicopter: what a marvelous British engineering achievement." James M. Wang is a senior contributor to a number of model helicopter magazines. His eight-page review of Hoverfly appeared in leading US journal Rotory Modeler, September-October 2001.

Let us switch gear and examine a very unique electric helicopter this month. This must be one of the more exotic RC helicopters that I have tried in the last 25 years of flying RC helicopters. The Hoverfly is a creation of Mr. Roderick Snell and his partner/chief designer, Phil Jermyn, from England. They envisioned a simple indoor electric helicopter that can be used as a trainer to teach people how to fly RC helicopters. Rather than using a conventional single main rotor design, his team ingeniously came up with a tri-rotor helicopter. The advantage is it eliminates mechanical moving parts such as swashplate, washout unit, mixing arms, flapping rotor, feathering bearings, etc. A tail rotor is still used so it will have the flight dynamics of a conventional single rotor helicopter. I am very impressed-the model may be unorthodox, but the handling characteristics realistically represent a conventional single rotor RC helicopter: what a marvelous British engineering achievement. No wonder they also pioneered the Harrier jump jet and the Pegasus engine for the Harrier.

The price of the Hoverfly is about 165 English pounds or US $235. The package includes the factory finished Hoverfly helicopter, an electrocyclic microprocessor controller box, and a power transformer that can be powered by the American 110 volt wall outlet or the European 220 volt power source. The Hoverfly comes with a 3.5 meter length fine wire umbilical cord that connects the Hoverfly to the microprocessor controller box. The modeler is required to supply his own 4 channels or more airplane or helicopter transmitter. The transmitter is connected to the microprocessor controller box through the trainer jack on the transmitter. The controller will work with Futaba, JR, Airtronics and Hitec transmitters. However, your transmitter must have a built-in trainer jack. Most of the modern transmitters, such as the Futaba 4 to 9 channel airplane and heli radios, the JR 4 to 10 channel radios, the Airtronics 4 to 8 channels and the Hitec radios all come with a trainer jack. The 110 volt transformer powers the microprocessor controller box and the Hoverfly through the umbilical cord. Since the model is designed to teach hovering in the indoor environment, so 3.5 meter length of umbilical cord is enough for most living rooms or game rooms. An optional 6 meter umbilical cord is available.

I used a model airplane optical tachometer and checked that each propeller spins at 25,000 rpm at full power and hovers at 20,000 to 22,000 rpm. Each motor is canted forward at about 15 degrees, which drives the entire main rotor at up to 250 rpm in hover. When more throttle is given, the three little propellers spin faster and produce more lift and the model rises. The entire main rotor will also spin slightly faster, but that does not contribute to any vertical thrust because there are no helicopter blades. I asked Mr. Snell, the president of Snelflight Technology, why not add an aerodynamic surface so the rotor can also generate some lift. He replied that they did try it-and many other things-and found the handling quality was not as good. Plus, the main rotor is only spinning at 250 rpm, so adding three rotor blade surfaces produces negligible thrust. Basically anything I suggested in our phone conversation were all tried during the Hoverfly development stage. It was such a pleasant experience to talk to Roderick Snell, we ended up communicating many times between the US and England by long distance telephone.

Please keep young kids back when flying the Hoverfly. The model is quiet and non-intimidating, but I was hit once by the little propeller and it caused little cuts because the plastic propellers spin at 12,000 rpm. The props are designed to break on impact. Every time I hit a wall or a furniture, a prop always broke, but never produced any damage to the model. In this respect the model is extremely rugged. Stock up on the tiny white propellers. I asked Roderick why not make the propellers out of flexible rubber? He responded they did try it but rubbery propellers can not hold the blade pitch angle rigidly. He added it is important that all three propellers generate identical thrust otherwise the helicopter will "wobble" in the air due to lift imbalance. The analogy is like a 3-bladed RC helicopter with a bad tracking. It should be emphasized that with a 3-bladed helicopter, a slight mismatch in blade angle will not cause too much wobbling or vibration because usually each individual blade can flap up and down to seek an equilibrium to compensate for the uneven pitch. The only consequence is one blade tracks higher than the other two. With the Hoverfly, the three rotor arms are attached "rigidly" to the rotor hub and there is no up and down flexibility. Therefore, if one propeller produces more thrust, it will produce a once-per-rev oscillation to the fuselage. Therefore, it is critical that all three tiny rotors generate identical lift.

The Hoverfly designer and engineer, Phil Jermyn, has devised an ingenious thrust measuring device for the tiny propellers so each production propeller is checked for thrust after they come out of the mold. The production propellers are then separated into eight numbered bins according to their thrust level. The three propellers supplied to each Hoverfly kit are matched thrust propellers from the same bin. Replacement propellers are always sold in a package of five, which is a bargain.

Surprisingly, the vertical response of the Hoverfly is better than a fixed pitch RC helicopter, such as the Ikarus Piccolo, MS Hornet, or the GMP Cricket. The reason is a fixed pitch helicopter has to spool up or slow down the entire main rotor, which has a longer time delay due to the massive rotational inertia. The Hoverfly vertical response does not depend on the main rotor rpm, it is pretty close to a constant 250 rpm. The vertical response only depends on how fast the little propeller is turning. The tiny 3 inch prop can change rpm instantly. Therefore, the Hoverfly does simulate a collective pitch helicopter as the designer has intended.

The Hoverfly uses a very smart way to control cyclic. It is smart enough to automatically vary the little propeller rpm (hence thrust) as the helicopter main rotor turns through different azimuth angle. The cyclic responses are not as fast as regular RC helicopters. The reason is RC helicopter main rotors typically hover at 1500 rpm, which means we get 1500 cyclic inputs per minute. The Hoverfly has a slower cyclic response for two reasons. First, the main rotor only spins at 250 rpm, so we only have 250 cyclic input per minute. The second reason is the little propeller needs to spin up and slow down as the main rotor turns. This is equivalent to changing the Hiller paddle angle and the blade pitch angle on our regular RC helicopters. More differential thrust variation on the Hoverfly would be equivalent to a large paddle angle change.

The Hoverfly designer picked 250 rpm for the helicopter main rotor for quite a few reasons. 250 rpm gives a very scale like rotorspeed. The designer can not make the main rotor spin too fast because the propeller thrust has to change as they go around each revolution. It takes time to speed up and spool down the propellers. Furthermore, 250 rpm only requires about 5 degrees forward tilt on the motor mast. The majority of the propeller thrust can be used for lifting purposes and only about 5% of the thrust is used to propel the main rotor. The Hoverfly is an aerodynamically efficient design. There are two benefits of having three electric motors spinning at the tip of the main rotor.

The motor mass provides gyroscopic stability and makes the helicopter very stable in the pitch and roll axes. As the electric motors are whirled, the airflow keeps the motors cool and that's why one can fly the Hoverfly continuously without overheating the motors.

Underneath the main rotor hub cap is a smart sensor system that allows the Hoverfly to know exactly where each blade arm is at any given instant, so cyclic thrust variation can be prescribed. The signals are communicated between the model and the microprocessor controller box via a very fine wire cable. The Hoverfly comes with a 3.5 meter (about 15 feet) long wire. Optional 6 meter wire length is available. To change the wire simply requires unplugging the wire plug at the helicopter. I have tried both 3.5 meter and 6 meter cable. For most indoor flying the 3.5 meter length is sufficient. The extra length will add weight to the model, but the Hoverfly produces more than adequate thrust to lift it. If you do not have a large room, then the 3.5 meter length is better because it is less likely to get tangled up and also less wire to reel up. The fine wire can form kinks if not careful, try to avoid them.

In the pictures I have shown both the Hoverfly II and the original Hoverfly I. Hoverfly II is the latest version and it has the black color rotor arm. The electronics in the Hoverfly II have been redesigned to make the model even easier to fly. Can you believe it, the Hoverfly has a built-in heading hold piezo gyro for the tail rotor? The sensors are located on a tiny board underneath the main rotor head. The heading hold gyro sensors are same as used in the famous CSM heading hold gyros and the designs are done in cooperation with the famous Mr. Colin S. Mill, who pioneered the CSM gyro. The tail rotor is driven by a thin rubber belt. The drive belt is powered by a tiny electric motor located at the nose of the helicopter for balancing reasons. Under normal hover conditions the tail rotor blades are turning at a very low rpm because the they only need to counter the drag from the main rotor bearing. Since the main rotor is not driven from a motor located in the helicopter fuselage, there is no reaction torque exerted onto the fuselage. This is a big difference between the Hoverfly and our typical single rotor RC helicopter. That is why in the 1960 many US and British full-size aircraft manufacturers explored the possibility of mounting a jet engine at the helicopter blade tip to do away with a tail rotor. The problem of those ideas was the loud jet noise as the jet engine gets whirled around at hundreds of rpm. On the Hoverfly, when a left yaw command is given, the tail rotor will spin faster one way, and when a right tail rotor command is given the tail rotor will spin the opposite direction. The built-in heading hold gyro makes Hoverfly tail so stable, unlike the Piccolo and Hornet, the Hoverfly tail control handles like 30 and 60-size gas helicopters: very impressive. I enjoy practicing slow pirouettes and the F3C Top Hat hover maneuver with the Hoverfly. In fact, one can practice the entire F3C hovering maneuvers in your living room.

I have tried my Hoverfly with a JR 8103 and a JR 652 transmitter, as well as a Futaba 8UH and a Hitec Eclipse 7 transmitter. All you need is a 4-channel airplane radio, a heli radio is not required. It will work with other brands not mentioned above, but then you have to figure out how to connect to the trainer jack and set up the jumper wires inside the Hoverfly microprocessor controller box. Since I know how to fly RC helicopters already, the Hoverfly is very easy to handle. I can hover it a few inches away from me for a long time. It is even easier to fly and more predictable than the Piccolo or the MS Hornet. The only limitation is the Hoverfly can not perform forward flight due to the umbilical cord. When trying out the Hoverfly for the first time, please let the propellers spool up slowly and let the main rotor build up rpm slowly, then lift off. Otherwise, the model will tip over or the model will take off sideway, then you will have a bull ride. Make sure you have no furniture within a 2 meter radius when trying it for the first few times. For experienced pilots, the Hoverfly is relaxing, but for a beginner it is just as challenging as learning to fly a gas powered helicopter. It will not be easy for the beginners and be ready to stock up on the inexpensive plastic propellers. Even I have broken five sets of propellers because of getting carried away and trying to land on bookshelves and coffee trays or got disoriented. Usually, the only thing that will get damage are the plastic props. If you do break other parts, the components can be purchased separately.

Beginners who find computer simulators boring, may find the Hoverfly more enjoyable because you can see something that physically conquered gravity and gets off the ground. Experience flyers will find the Hoverfly entertaining. Currently, the Hoverfly is only available from England. Either order through Midland Helicopters Hobby Shop in UK at tel: 44-1455637762 or fax 44-1455619348 or by emailing trevor@midheli.co.uk. In UK, the Hoverfly is sold at any hobby shop that is served by the Ripmax Distributor. Roderick Snell and Phil Jermyn are exploring USA distributorships to carry the Hoverfly in the US. You may reach them by email at sales@snelflight.co.uk. Phil says currently it cost about US $30 to ship the Hoverfly from UK to the US by airmail, and that only takes 5 days.

Finally, I will conclude my review by including a wonderful letter written to me from Roderick describing his experience.

Dear James,
I bought a Kalt 'Whisper' kit a few years ago, hoping to learn to fly without the noise, mess and problems that newcomers have with low nitro high compression glow engines. It was a bad choice: the extreme fragility of that early version, with its low rotorspeed was not that stable for beginners and aided by the massive weight of the NiCd cell, crashed destructively to earth at the slightest mistake. It was not just the tail boom, blades, rotor mast, skids etc, but the main frame often broke off at the junction with the boom; this required a total rebuild of the machine. My rate of learning was far outstripped by the crashing and rebuilding. At this point I took to cheap simulators (befriending Colin Mill in that process), and found them very helpful. When learning on a gas or electric helicopter, you would bump around on the grass for a long time before allowing even a few inches between ground and skids. In flying the simulator, you throw the model high into the virtual empyrean and try to learn to fly the thing before it hits the deck. This can be repeated as often as you please but it does not, in many senses mimic the real experience.

I then moved up to the Kyosho Concept 30's and today I am horrified when I come across my large box of bent rotor masts, each one representing at least a boom strike, a blade set and the usual rage of extras. Fortunately for my self-esteem, most of the other broken bits are thrown away. There seem to be at least three categories of beginners: those who are brilliantly quick at gaining the skills needed, those who were surrounded by nearby helpful clubs with training links to compatible transmitters, and those slow learners like me with precious little spare time who grind on supporting the local parts shops and eventually reach some level of sports flying. It is an old story, which I am sure, you have heard many times before.

Our aim with the Hoverfly was not to compete with the increasing list of small electric helis and flying machines, which are less robust and have too short a flight time to help the beginner. The newer, smaller electrics like the Piccolo are slightly less fragile, but I find that their fixed pitch and consequent slow vertical response are harder to fly than a conventional 30-size engine powered machines. I tried to encourage the American Arlton brothers (who designed the LM100 Lite Machine) to get into electrics with their LM100 design some years ago. But I then electrified my LM100 myself. It flew, but flight time was still a real problem.

To quote Mike Mas, it is "stick time" or gallons of fuel that gets the learner to first base as a pilot (and a lot more if you are past your youth). This is not easy in the winter or in our unpredictable climate. So when I first saw the fragile balsa prototype Hoverfly with no flybar or swashplate, no overdriven battery to carry and potentially a much lower cost, I was intrigued. Most important of all, flight duration is infinite, or for as many hours as the novice can concentrate or the experienced pilot wants amusement. I, for one, no longer saw the thin tether as an impediment, at least you could not lose the machine!

The main challenge was to find a way of replacing the balsa frame with something more rugged but equally light and manufacturable. We did not make a kit because we thought buyers would not want to pay for the necessarily ready-built electronics if they only got a low-value kit. Because of the pre-assembled helicopter and the pre-aligned electronics we might be the first to offer a product which is pre-trimmed and will fly straight out of the box. The first challenge took many months of patient work, shaving tenths of a gram off everything and optimizing the twenty-odd plastic moldings for weight and crashability.

Starting with the national sales only for the Hoverfly I, we have supplied nearly one thousand units to a wide range of ages and skill levels in the UK. This experience with monitoring and backing up the local users has all been fed into the Hoverfly II. Many sales were to newcomers (including fix wing flyers) who would not have gone through the labor of assembling a Shuttle, finding a club with a field, etc, but who just wanted to see a tiny model helicopter hovering in their lounge. A useful percentage of these beginners then move onto real free-flying outdoor models, having gained both confidence and orientation skills with the Hoverfly. If we can find the right way to market it, I am confident this little model can bring many newcomers into our wonderful hobby.

Regards, Mr. Roderick Snell

As he has pointed out, each Hoverfly has been flown at the factory before shipment. And, one can fly the Hoverfly for as long as one wants until he gets tired. The four little electric motors will not get hot and you are only limited by how long your transmitter battery can last. Since the transmitter is connected through the trainer jack there is no RF signal generated, the transmitter can operate for at least two or three hours on a full charge.

Photo Captions 1. James enjoying the Hoverfly II indoor electric helicopter from England. 2. The Hoverfly II comes ready to fly and already test flown in the factory. 3. The Hoverfly rotor diameter is less than 12 inches and weighs less than 5 ounces. 4. Three electric motor power the three rotor propellers and a fourth electric motor powers the tail rotor. 5. The older Hoverfly I is dwarfted by the Hitec Eclipse 7 transmitter. 6. The tail rotor motor is hidden under the canopy. The Hoverfly II includes a heading hold piezo gyro. 7. The belt drive tail rotor with the heading hold gyro gives precise yaw control just like the bigger models. 8. The Hoverfly kit includes a free training gear for the beginners that's made of two straws. 9. The Electrocyclic microprocessor controller is the brain of the Hoverfly. 10. James has hit the furnitures in his living room many times, the only damages are the tiny plastic propellers. Don't glue them back because that will cause vibration. 11. The machine designed by Phil Jermyn to measure each plastic propeller coming off the production line. The props are then separated into eight thrust categories.
 

"... once you start you're hooked ... the fun is endless." Stuff's staff clearly love the Hoverfly, with a second endorsement in six months. Under the heading Flight Club, the magazine lists just one helicopter among six highly-praised remote-control aircraft. July 2001.

This unique indoor helicopter comes fully built, although you will need to buy a radio controller for it - despite the fact that it's actually connected by a thin cable. Don't be put off by that, though, as this little beast is hugely entertaining and will easily eat up your weekends. Getting the Hoverfly to hover or fly is no mean feat, but once you start you're hooked. A helicopter can move in so many ways (including our speciality - straight into the carpet) but with practice you can recreate the beach landing scene from Apocalypse Now. The fun is endless.

Airspeed N/A; Batteries No, 38v DC from mains; Number of channels 4; Range 3.5m (length of cord); Weight 68g; Wingspan 30cm
 

Under the headline "Dream Machine", Dave Ridgeway writes in Model Flyer, January 2000, in his column Bright Sparks - "Watts" going on in the world of electric flight

With the advent of micro electronics the modellers dream of flying a radio controlled model in his living room has become a reality. Just take a look at the incredible Snelflight Hoverfly helicopter. This tiny helicopter is one of those inventions that makes us lesser morsels just gasp with admiration. For a start, there are no conventional blades on the rotor, instead there are three small motors mounted vertically on the end of each of the rotor arms, these are inclined at a small angle to make the rotor rotate. The rotor shaft has in effect a commutator to supply current to the motors as they rotate at around 100rpm. The tail rotor is quite conventional (by the standards of this machine!) and is driven by a tiny motor at the front of the helicopter via a belt drive which passes through the tail boom.
Power to the model is via an attached, very fine 15 strand cable from a mains transformer supplying 36 volts. A very small solid state gyro was carried on the example I saw perform, although I understand it can be flown without this. The umbilical cord plugs into the "clever bit" - a box crammed full of electronics, the other end of which plugs into the "buddy Box" socket of the transmitter. This incredible box of tricks converts the input from the pilot to control the motors to give exactly the same control as a normal radio controlled helicopter.
The Hoverfly shown here was owned and demonstrated by John Gunia, who is a very experienced "heli" pilot and has flown just about every type of model chopper large and small, he assures me it performs in the same manner as its much larger brethren. John was amazed at the stability of the model and its very smooth response, not "twitchy" at all - unlike many very small machines.
The "Hoverfly" was demonstrated to me in quite a small kitchen with no difficulty at all! Also evident was that it had plenty of performance and would leap vertically if required. Apparently the Hoverfly is not intended as a "toy" but as a serious training machine, with the advantage that replacement parts are very cheap when compared to normal helicopter prices. Although the Hoverfly is not a true "free flight" craft as it has a permanently attached power cable, however this is not a disadvantage as it means you can fly as long as you wish to. John admits he is absolutely delighted with his, finds it hard to put down.

Unfortunately the photographs do not do it justice as the rotor arms appear to be stationary, in reality it appears to the naked eye just like a conventional model, it also sounds great.
 

"... novices can learn to fly with it, more experienced pilots can practise their nose-in flying and experts can have enormous fun," comments Aviation Modeller International, February 2000, in its column Straight from the Box - What's new on the ARTF scene?

Despite the title of this Column, we all know that in reality, virtually nothing comes actually ready-to-fly. Alright, there are exceptions like the Cox control-line series, but beyond those, what is there?

To your minimalist list, you can now add the name of the Snelflight Hoverfly.

The WHAT? This is a highly innovative indoor helicopter, with the added distinction of actually having been designed and manufactured in the UK. And as a further 'novelty', instead of being launched amid a great deal of hype and publicity, the manufacturer is deliberately playing it low-key, initially producing a few limited runs retailed by specialist concerns, so that he is convinced that the product is 100% right before going into volume production.

So just what exactly is the Hoverfly?

The short answer is that it is an electric powered, indoor helicopter: by indoor we mean one that can be flown in your living room or garage - not a large hall or leisure centre.

What it is NOT, is conventional.

That means forget about collective or fixed pitch and complicated rotor head linkages: there are no rotor blades. It doesn't have servos. Or a NiCad pack.

And yet it flies exactly like a conventional (model) helicopter. That is most important, because it means that novices can learn to fly with it, more experienced pilots can practise their nose-in flying and experts can have enormous fun - including chasing flies around the room and generally annoying their partners trying to watch television ...

Having said what it doesn't have, how does it work?

The helicopter is supplied as a 'set', comprising a mains power supply, an 'electrocyclic control processor' (henceforth termed an ECP) and a fully-assembled model helicopter with a lightweight plastic body and tail boom carrying a lightweight tail rotor.

To get ready for flight, it is just a case of plugging the lead from the mains power unit and a training lead from your transmitter to the ECP - and from there an 'umbilical cord'-like collection of fine wires run to the helicopter. There are no servos or NiCads, because the ECP contains all the clever electronics and sits on the floor, and there is a 3.5m bundle of fine cables taking power to the heli: ample length as you have over an 11 feet radius hemisphere in which to fly. But for those who will want more, a 6m option will be available

By leaving out all the traditional heavy hardware, the helicopter is extremely light (around 66g - say 2.3oz.) which means that it is far less likely to damage itself when it collides with an obstacle: it tends to distort/flex rather than break. Yet despite that low weight, it has a 12in 'rotor' diameter and is some 16in long overall. Mains power means no restriction on how long you fly for, and as you are using your existing transmitter for control, you can set up all the control throws and sensitivity to suit your preferences.

Instead of rotor blades, there are three rotor arms, each carrying an electric motor mounted vertically, and fitted with a conventional prop. At the hub is a very clever 'distributor' rather like an electric motor's commutator, that feeds the power to each motor, at the command of the ECP.

Watching the Hoverfly at low throttle on the ground reveals how it works: as the rotor arms rotate, the motors are switched on/off according to your control inputs. For example, if you want to go left, the motors are switched on as each rotor arm in turn passes the right side, then off (or less power) as they pass the left side again. Going up? All motors stay on. Get the picture? The rotor arms are not actually driven, they rotate due to torque reaction from the electric motors: at peak speed they are turning at only about 250rpm, another reason why they can hit obstacles without damage. A featherweight gyro is now fitted as standard, and keeps the tail under strict control.

The above of course is a great simplification: the electronics have to work out how much 'lead' time to give each motor time to spool-up/down, and that means lots and lots of development work. All the time, the designers were anxious to maintain the right 'feel' and handling characteristics of a model helicopter, and Bob Johnson provided invaluable assistance in this direction, also collaborating with CSM who are updating their Flight Simulator software to include the Hoverfly as one of many options.

Dick Wallinger of Midland Helicopters showed us the Hoverfly in action, and it was indeed most impressive. He agrees that it handles just like a normal outdoor heli, perhaps being just a shade harder to fly: don't make the mistake of thinking that this is a plug'n'play toy with instant success. It is not, and really that is its strength.

Instead, from the (literal) comfort of your armchair, you can learn to fly a model helicopter IF you put in the time/concentration/effort. No waiting for the weather to improve, no fuel to burn, nor batteries to charge or model to set-up.

Now if you think that a trio of electric motors pointing upwards each mounted on a slowly-revolving arm plus a bunch of wires (14 actually) reaching from the ground to the model all adds up to a pretty unconvincing image of a helicopter, then you'll change your mind when you see it. For a start, the rotor speed is very scale-like, and secondly you do not 'see' the electric motors: it is just a blur. Unfortunately, the camera's flash 'stops' the rotors in action, so what you see here is not what you actually get. Believe me. Secondly, that umbilical cord is so fine that the pilot will not be aware of it at all: he will be focusing entirely on the model, the sheer number of 'strands' ensuring that the cable remains flexible and not kinking/breaking. Seeing is believing.

As a further endorsement of its teaching-ability, a 12 year old lad has been flying the Hoverfly, but had never flown a 'real' heli - until his father handed him the transmitter to a Baron 30S, which he immediately put into the hover and handled the gusty wind conditions with confidence.

Man behind the project is Roderick Snell, who runs a very successful business in the broadcasting industry, and an enthusiastic model heli pilot, albeit still undergoing the learning process (does it ever stop?)

When approached by the originators of the concept, he agreed to help get the model into production, but was adamant that he wanted to see it manufactured in Britain, and not simply sell the licence to a company in the Far East. He was also insistent that the product had to be RIGHT and is not looking for a short-term return on his investment. Consequently, the actual numbers produced so far is numbered in hundreds, and no distribution rights have been assigned.

"I wanted feedback from customers before we went into volume investment, and I have appointed just four retailers at the moment - all experienced helicopter people who can look after and advise their customers". He added... "If there is a problem, then we can identify it and fix it quickly before we gear up for volume production. It is simple to look after the needs of a few."

A pity more people do not take that attitude, rather than buy-in container loads of products from overseas, then find a host of problems which will not be corrected until the next shipment. Or maybe the one after.

In practice, the customer feedback has been very positive, with very few problems arising - and those that have being readily fixed.

Now the bad news. You probably won't be able to get one just yet, although another small production run should have been completed before Christmas. Be patient though, because plans are in hand to produce more for January 2000, and volume production should have started by the Spring. An aluminium carrying case is being made available as an option, so if your work involves nights away in hotels, you can keep your hand in. How you explain to your wife that you had a model in your room is your problem!

Dick Wallinger ponders the meaning of life - and wonders why he goes outdoors to get cold and wet to fly, when the 'Hoverfly' can be flown from the comfort of his own armchair.

Rock-steady in the hover, the 'Hoverfly' can be flown safely in extremely small spaces. The camera does lie, or at least the flash halts the action: what you actually see is a blur as the rotors go round - no props or electric motors are visible to spoil the action.

If you were a fly, how would you feel about this object chasing you?

Under the lightweight body shell there's not a lot to see - other than a featherweight gyro - as all the 'clever stuff' is in a box on the floor

The 'Hoverfly' is a great example of lateral thinking - and it works!

Who needs a receiver and servos? Not the 'Hoverfly' - all the clever electronics are in here, and stay safely on the ground. Just plug in your transmitter buddy-box lead, the jack plug from the mains-DC converter and the 'umbilical cord' to the heli - and that's it

"... lots of uninterrupted stick time without long pauses for charging a flight pack,"

"... swiftly rectifies ham-fisted aerobatics" - proving that even non-enthusiasts can get the hang of Hoverfly! The top lads' mag FHM gave it the thumbs up in a major "Gizmos" feature, November 2000.

"... after a couple of hours, you get the hang of it" writes Stuff's columnist about the latest remote controlled toys for (biggish) boys - confirming Hoverfly's place in the model aircraft world. He awards it four red stars for quality and appeal. December 2000.

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