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Care and feeding of Micro Helicopters.

Contents.
Start here.
Stage One: Learning to hover.
Stage Two: Moving about.
Stage Three: Have fun.
Racing.
Repair.
Going furthur.
A totally trashed helicopter.
Summary.

First - thanks to all the designers who helped create these mini marvels.
Thanks also, to all those who work in those godless factories making shoes and mini helicopters and just about everything else. (Not unlike the endless 'dark satanic mills' of Britain a century ago.)
Thanks to the micro electronics designers who have made marvels we hardly know anything about. (But say NO to RFID chips.)
No great thanks to the translators who give us the old style translations of yore. (One of my Japanese parts manuals has 'steering pipe' for handlebars. If the manufacturers want a translator, I'm a white, middle aged with B.Sc. and B.Ed, British engineer - so am of course unemployed ! - I'd be only too glad to help, and for mere pennies. Half a job is better than nowt.)
Gizzajob.

The micro helicopter instruction sheet leaves much to be desired, hence this web page.

The early development of this probably began in the USA with micro spy planes, when model makers were developing close range spy planes for the military. The big flying models were effective, but 'pocket' versions were also being developed for ease of use. When miniature lithium polymer battery became available en masse, a development of cellphones and digital cameras, plus incredibly small electric motors, also made in the affordable millions for cell phone vibrators and digital camera zooms, then the future was set for fun.
The model helicopter part of the formula became possible when the stabiliser bar was developed and set at the most effective angle relative to the main blades, plus the micro tail motor and the very light weight lithium batteries, both being made by the millions with a flattening market, so they had to find a new commercial outlet for the '3.7 volt range' of technology.
Add a length of pultruded carbon fibre tubing from kites and the technology of the TV remote control and bingo !
It can only get better.

Flying can only get better. - oh so much better.
I've help build and fly IC engine radio control helicopters and they are just a sheer pain to fly, even with gyroscopes. Just don't bother.

As for micro electric helicopters, they are not only far cheaper, they also fly far easier to fly than anyone would care to expect. Mine cost fifteen quid and flies rather well. (I'm sure the balance bar above the main blades is worth its weight in gold.)
The helicopter in the picture is just one of many designs available on the high street, but this one I prefer. The others have larger, bulkier foam bodies and look rather tatty. But theier esxpanded polystyrene bodies apeoabaly more damage reistant. This one has a compact cockpit and therefore offers less aerodynamic drag. Less drag always makes for a better flight with probably slightly longer flight times, with less stress on the motor and gearing.

Start here.

Fit the batteries in the control panel.
The charging lead is hidden in the panel in the front. The cover is a little stiff to slide downwards.
Fitting the charging plug in the base of the helicopter is fiddly, so check the pins line up and never force the connection.

Tip : I've put a small dab of felt tip marker on one side of my charging plug so I can insert it correctly, and make life easier, as the connection pins are very, very small.

Switch off the helicopter. Very carefully plug in the lead to charge the helicopter battery and switch control box on. A green light shows charging.
Allow about 20 minutes to charge fully: The green light will go out.

Warning : After flying, always allow 10 minutes for the battery to cool down before recharging. - These Lithium polymer batteries are very sensitive and can catch fire and explode as per some laptop batteries.

Tip : While waiting for the battery to charge, - especially if flying from the floor - put the vacuum cleaner around the area first, so no strands of hair will clog or damage the drive gears or tail rotor. The helicopter throws up a lot of draught, so look after your little marvel from the outset. If you should get the tail rotor entangled with hair or fluff, then simply pull the tail rotor off for easier cleaning. If the helicopter ever spins more than usual, then check this area first.

When charged up, disconnect the helicopter and switch off the control unit.

Check the flying area has no perceptible draughts. Close windows if windy.

Tip : (If you can fly from, and land on the soft duvet of a double bed, then do so, especially for the first few flights until you become proficient at controlling the wee beasite.)

Stage One: Learning to hover.

Place on flat level ground.
Switch on the small switch under the nose.
Check the frequency (1,2 or 3) on the control panel for the particular helicopter. This allows up to three machines to fly at once in the same room.

First flight.
Stand clear and do just a couple of quick jumps into the air, enough for it to settle down and stop spinning, hover happily, then back down again.
To fly, simply push FULL UP, then immediately ease off the throttle to allow it to hover. Try to hover at about shoulder level. Then let it to come back down slowly.
There should be a smile on your face :)
The first little jaunt should be to get to know the throttle control.

Tip : Use full throttle for take off. If you gently throttle up, then it is more likely to spin out of control. Opening the throttle slowly will only cause the helicopter to spin more, due to torque reaction. The power is marginal, so full throttle will do no real damage if you ease off soon enough before hitting the ceiling.

In reality, the helicopter will spin as it rises, then settle down and drift about the room, but if allowed to fly without hindrance, it will hopefully crash somewhere soft, or have a low drop to the ground.

(You will notice that the designers have made a rather good, sprung loaded throttle lever. Of the many Radio control throttles I've used over the past few decades, this cheap item is perfectly suited for its purpose.)

Second flight.
The next flight is to launch into the air again, but this time just hover at about eye level. The helicopter may spin, but this is a good thing as it will simply keep it from drifting about the room.
With the helicopter hovering, use the right control to stop it spinning. Now let go the lever and use the adjustment buttons to reduce the spin by one press, then a wait, until it settles down and stops spinning. Then back by one button press.
The helicopter should now be fairly controllable and ready to enjoy.

Tip : Stable hover. Don't bother with the left - right control lever until if flies up then straightens out. Use the trim adjustment until it is fairy stable in the hover. When hovering, trim out the spin using the small adjustment buttons under the Left - right control.
ONE little press is usually quite enough, as the helicopter takes a second or so to settle down. So when you have the helicopter hovering, allow it to stabilise then make ONE press of the adjustment at a time, until it hovers without spinning.
If a lot of spin needs adjustment, then press three times one way and when the helicopter has almost stabilised, one press the other way to ensure it remains in the stable position.

The first few flights will be purely learning to open the throttle fast, then ease off to allow the craft to hover gently, and then lower back down to the ground in a safe manner.

Tip : Stable hover. It will be noticed that the hover can be adjusted to enable the helicopter to remain in one place. Unfortunately, as the power is increased or decreased to adjust height, the helicopter will naturally tend to rotate left or right. Therefore the pure hover is the position where it should be adjusted. Only adjust the trim by one press and wait a few seconds.

Tip : Damage limitation. To save undue damage from falling to the floor, practice letting the helicopter to fly gently down to the floor just before it crashes. A two foot fall (0.6m) is a lot safer than a four foot fall. (1.2m) When you see that the helicopter is not going to make a safe landing, then throttle back to lower as close to the ground before crashing to reduce damage. Whether real crashes, or just toys, a gentle crash is always preferable.

Trim : When you have learnt to hover, then carefully take a note of how the helicopter sits under the rotors when seen from the rear. If the helicopter flies slightly askew, then place a little blue tacky office putty on the high side, to allow the helicopter to fly level and more easier to control. More about trimming the craft later.

Tip : Better throttle control. Holding in the hover, need not use the finger on the top of the throttle lever. Simply resting the thumb against the lever should be enough to control the helicopter in the hover with a much better, single handed grasp of the control box. This leaves the other hand completely free for launching and retrieving the helicopter.

Trim : The models are almost perfectly trimmed straight out of the box. The trim set up will depend upon the model, but when the helicopter is held by the main blades, it should sit with the main shaft vertical. If it sits slightly nose down then the tail rotor should point down slightly. If the helicopter sits nose up, then the tail rotor should point upwards slightly.
After a particularly bad tail-end crash, if the helicopter flies forwards too much, then twist the tail boom so the tail rotor points a little more downwards. If the helicopter flies backwards, then twist the tail boom so the tail rotor points upwards a little more. What is happening; the tail rotor either gives too much up thrust (causing forwards movement) or too much down thrust (casing rearwards movement).

Tip : Hand launching. When launching from the hand, a small tilt forwards will allow the helicopter to move and hover a few feet ahead of the user, preferably for a soft landing on the bed or table top.
With practice, the amount of nose down when releasing from the hand will allow you to decide the distance the helicopter will fly forwards before it slows down and starts hovering.

Tip : Hand landing. To land on the palm with minimal hassle, shut off the throttle just before it touches the hand. This saves the rotors turning, and greatly reduces the chance for the helicopter to fall off. With practice, the helicopter need never fall to the floor again.

Stage Two: Moving about.

It will be noticed that the helicopter seems rather random in its movement.
Even in a perfect hover, there are air currents in the room. It is now time to take control of the movement about the room.

Going forwards a small distance, then hover.

Hold the helicopter in your hand and gently tilt it sideways and fore aft: You can see the Stabiliser Bar above the main blades will move to gradually align with the main rotor shaft. Any undue rocking movement of the helicopter will maintain stability, but gradually cause the rotor bar to line up with the helicopter shaft. Because the weight of the helicopter hangs below the rotor blades, then the weight of the helicopter, under the influence of gravity, will gradually want to straighten out and turn to the hover, due to the effect of the stabiliser bar.
Therefore tilting the helicopter forwards (without any weights) will allow the helicopter to fly forwards, but gradually slow down and stabilise in the hover under the pendulum effect.
When the helicopter is weighted such that it tilts slightly forwards when suspended from the stabiliser bar, then this will become the natural, stabilised position for the helicopter, and thus it will constantly fly forwards.

The final step is to fly forwards.

Note: It will be seen that the hover is never quite perfect and the helicopter will want to move about a little. By careful adjustment, the helicopter can be trimmed to do a small circuit rather than a simple hover. This is done by a little amount of weight on the front. It is possible to also twist the tail rotor motor to point upwards a little, but if the helicopter hovers nicely, then leave well alone and just use small nose weights.

True control is done in the forwards direction when the helicopter is trimmed to fly straight ahead. Turning is then done by directing the helicopter sideways by a few gentle nudges of the left-right control lever and waiting for it to gradually change to the new direction. You cannot steer a helicopter like a car, but like a hovercraft, only coax it into a new flight position to gradually change its direction.

Going forwards will allow the helicopter to be more controllable than just hovering and randomly moving.
To go forwards, the solution is simple - tilt the nose down to use part of the rotor power for a minor forward thrust vector. This is done by adding weight to the front.

After a dozen or so flights, when you have good hover control, then one of the lead weights can be added to the nose, to cause the helicopter to fly forwards slightly. The weight permanently changes the upright position in the hover and tilts the helicopter so its main shaft is pointing slightly forwards, allowing constant forwards movement. More weight, greater forwards speed and more difficult to control in the turns.
This forward movement then allows the tail rotors' left - right lever to help guide the helicopter around the room. - It is no longer a toy or amusement, but a true, if basic flying helicopter.

Start off with a small weight, which just about gives some forwards movement and learn how to turn well before needing to. Rotate the helicopter sideways, so it begins to turn to the desired direction. Learning to turn under control is best done in large open areas, as turning takes a lot of room unless you are very skilful. Turn the helicopter then wait for it to gradually change direction.

With a little forward control weight, the helicopter can be coaxed to rise and then move forwards. As the directional stability is not perfect, it may veer to one side, and may well do a nice, neat, slow, circuit of the room.

Tip : Trim weights. Using blue tacky office putty to the noise instead of the lead weights, allows more adjustment and allows removal of the weight and simply hover. Compare your weights with the weights supplied in the box for the right mass. You can stick the spare weight on the control box to easily adjust the placement and mass of the nose weights to match the different rooms.
(Do not be tempted to adjust the tail rotor up to cause forward motion, as constantly adjusting the tail can lead to fatigue on the boom. Only do this if intending to only fly forwards all the time, or if setting up to race around a circuit such as in a hall for competitions. If intending to hover as well, then preferably use removable weights.)

Tip : Trim weights. When hovering, note if the main shaft is truly vertical. If not, then apply any trim weight to the side of the nose to counterbalance any tendency to hover with the main shaft slight tilted. Looking from the rear, hover and compare the shaft with the side of a vertical window for checking purposes, then apply any trim appropriately.

NOTE: Well before reaching a wall or obstacle, the helicopter must be subtlety turned to allow its forwards movement to change slowly to the new direction. - This takes time and is probably the hardest aspect of control.
Real helicopters can bank left and right and tilt forwards and back. The micro helicopter cannot.
The wee beastie is a bit like a train on rails - it wants to continue in its natural direction. Therefore always decide where to turn early, well before needing it. This control is very similar to hovercraft, where they turn very early, before the corner.

Eventually you can make the helicopter do a (simple ?) circuit of the room and land upright, very near to the start point.

Lack of the third control. (pitch).
It may be noted that the helicopter can only be set to hover or move forwards, due to only two controls, rather than the third, extra pitch control to allow forward or hover motion. This is NOT a problem, because helicopters have a trick up their sleeve which other aircraft do not have: They can turn fully around while in flight. Even when moving forward, a helicopter can face backwards simply by using the tail rotor control. This in effect acts as a substitute to the third control.
For example, if wanting to hover over a single point, even though the helicopter is trimmed for forwards flight, then simply face backwards when approaching the desired destination point, and then gently rotate to maintain a controlled hovering position as the helicopter descends to land.

Tip: Save the battery. After many or long flight, the helicopter may be seen to be unable to sustain hovering and gradually loose height or need more power to maintain height. This is the time to land, to allow the exhausted batteries to cool down, then recharge. By stopping before becoming fully exhausted and to cool, the delicate lithium polymer batteries will last a great deal longer than if mistreated by total exhaustion.
Lithium polymer batteries will last up to three times as long if treated well, so ensure you get many months of flying rather than many weeks before the batteries die through overwork. Always give them chance to cool down.

A standard pack of 6 AA alkaline batts will charge up the helicopter twenty times or more.
Always let the lithium polymer batteries cool down for 10 minutes before recharging.
The larger helicopters use Nicads or NiMh, and these should also be allowed to cool.

With the skills to hover, trim for forwards flight and launching and landing, the user of a micro helicopter should now be able to sustain flight in a standard room for many minutes. With time, it will be seen that there is still a randomness to the flight, and this is due to draughts of air. Note the placement to doors and windows.

Please don't be a twat: Some sets are sold as 'battling helicopters' and this is an awful shame when such superb technology is reduced to just more consumer crap for decadent twats and spoilt kids.
Try to be a little more sophisticated and develop real helicopter skills.

Racing 1 :
The greatest advantage of micro helicopters is that they charge up fast and you don't need a power socket, so they can be used anywhere. True pocket racing.
For easier carrying, the control box sticks can be shortened to personal preference.
If you have friends with similar machines, then first check which can fly on the different frequencies. Then switch on your helicopter to check there is no danger of cross interference.

In a small room, hang a piece of cord with a small weight from the ceiling to build an obstacle course. Race the circuit and back to a large circle on the ground for first place. Or once around the lampshade and back to land.
You will gradually refine the mass needed on the nose for faster flight with good manoeuvrability.
If only one helicopter, then time each persons' circuit.
Flying under the table, take off and land on a bookshelf, if appropriate, and lots of other ideas can gradually make longer or more complex circuits.
Flying through a door or a window can be a real challenge as there may well be draughts to contend with.

Ask around and get as many friends as possible then hire a hall or a friends large room for an afternoon and evening of racing.
Make up some impromptu prizes and certificates for: Accuracy on a landing spot, fastest into all four top corners the room; longest skid landing.
Where large rooms are unavailable, ask your local sports or community hall for the charge for an hour or two. Put posters up and if many, then start your own club, to simply cover the cost of the hall.

Warning: Micro helicopters are for indoor use only, so flying outdoors may have problems, where transmission reflections off cars and lack of range will always be a problem. So always do a test flight by walking as far from the helicopter as needed before testing. Expect glitches and if they occur, get close to the helicopter to maintain control. Stay close to your machine, but always keep one eye open for other racers.

You may wish to race in the local park on a day with zero wind. To check, take a couple of bamboo poles with a foot of thin ribbon or fluffy wool to show the wind direction and strength. Tying a piece of fluffy wool to a tall tree will upset nobody, but allow instant assessment on the way back from school or work. Bamboo poles also make excellent racing poles for a circuit. A race circuit need only take 30 seconds to make.
If there is a slight breeze, then micro helicopters can be raced purely downwind, if there is no chance of getting back to the start.

Dumpstering: Hover over a dustbin and dipping in and out. Can get smelly if you loose control, so always ensure line of sight between the helicopter and control box.

Circuits and Bumps: Rather than have to create a fast circuit, just lay out jackets, pullovers or bags on the ground, then doing pinpoint 'circuits and bumps', by bouncing off each jacket in turn, can also make a strong challenge. Either in a straight line downwind if slightly windy, and measure the time taken, or in still air, make a circle and see how many bumps can be done in three minutes.

Helicopter Golf: Start the stop watch, take off from the Tee, run with the helicopter to around the golf hole flag pole to land. A small, quiet municipal golf course would be ideal, but don't upset the dedicated golfers, as they can be real pains- they think the world belongs to them. Probably wannabe councillors, accountants or freemasons.
Helicopter Golf is ideal for the larger outdoor helicopters, and with a few spare battery packs, a 19 hole course is possible. (19th hole being the cafe or pub afterwards. Like surfing and skateboarding, always make modelling a social as well as technical hobby.)

Office fun for execs : A hard skill is taking a paper note across the office, then landing back on the office desk. With a little skill, a small sticky 'yellow sticky note' can be placed on the skids, facing down, so it does not interfere with airflow and flown across the office. The recipient can gently hold the helicopter and remove the note, then release it back to home. (Preferably releasing by pointing it with a little tilt forwards to help return to its desired direction.)

Permitted 'cheating' may include any non contact means of helping maintain control, such as blowing on the helicopter or using a small folding paper fan made from a sheet no larger than A4.

Racing 2:
Sometimes a standard machine is just not good enough.
If intending to race the beastie, then loose weight and streamline.
Weight reduction reduces the power to remain aloft and therefore will fly for a slightly longer time.
Carefully remove the plastic cockpit cover. It is possible to cover the batteries and electronics with a minimalist shaped piece of paper to reduce downwash airflow.
This change in frontal mass will upset the trim, so the tail rotor may need to be tilted upwards to compensate without adding extra mass to the nose, but by far the best option, is to move the battery slightly forwards for perfect trim.

After removal of all unnecessary weight, my helicopters have the mini lipo battery moved forwards using a couple of double sided foam pads to hold the battery upright, and pointing forwards to optimise the balance when held but the stabiliser bar. Another advantage of having the battery mounted forwards like a thick rudder, is that mine is tilted slightly sideways to create a compensating deflector to offset the natural thrust of the rotor head. To check the direction of deflection, note the torque reaction on take off and angle the vertical battery to deflect sideways downwards airflow against this rotation. It also tends to increase the polar moment of interia about the yaw and pitch axes.

Whether to decide to streamline or not, or the whole airframe, or part, or just the battery pack is up to the owner.

With even the simplest modifications, now run some control tests and if needed, some speed tests over a set distance to assess the best design.

Impeccable balance would be to have the tail rotor perfectly level, but this will require perfect balance. For perfect balance, move the battery pack slightly forwards, so that the helicopter sits perfectly level for hovering, or tilting slightly nose down for forwards flight. Hold the helicopter by the main blade, so it's at 90 degrees to allow the helicopter to swivel freely. Then compare the vertical alignment of the main shaft relative to the side of a vertical building wall. Hovering is true vertical. Slow forwards is about 2 degrees nose down, and faster is 4 degrees or more. (My tail motor shaft is horizontal.)
Also adjust the mass slightly left or right so the main shaft balances vertically when seen from the rear.

Only make major changes if intending to only fly forwards all the time, such as setting up to race around a circuit in a hall for competition. Then finally adjust the battery weight to fettle the final racing version for speed with reasonable handling. Hovering ability can then be returned by adding a very small weight to the tail.

Other racing options:
Perhaps reposition the battery to a more aerodynamic alignment to reduce drag.
Always be very careful not to obscure the sensor control beam from the control box.

Perhaps move the tail fin to the rear for greater straight line stability and to make it from larger, thin, stiff paper to reduce weight, but do not upset the tail rotor airflow. If making skid landings because your helicopter has lots of forwards movement, then a tail fin can also be designed to protect the tail rotor.
To save weight, loose the skids, but make sure any crash landing will not break the on / off switch on the bottom, so use a little foam (bath sponge) covered with a piece of thin, hard plastic slid (cut from a pop bottle) to make a shock absorbing minimalist belly skid.

Adding a little weight to the rear is possible to return a racing version back to hovering mode.

Racing can get competitive, so any specialist helicopter should be carried in a special box, lined with foam. The transmitter is fairly robust, but the helicopter can be carried to work or school in a cardboard tube packed with slices of bath sponge. (If you think it's not for kids or grown ups, then remember that the staff of some large firms play street hockey in the carpark at lunch time ! Enjoy life.)

Do not meddle with he stabiliser bar. It will be noticed that the weight of the helicopter is suspended from the main blade pivot, so the helicopter mass will naturally want to line up vertically under the influence of gravity. To ensure this happens, the stabiliser bar always wants to spin at right angles to the main shaft, due to centripetal force and thereby the helicopter tries to remain vertical at all times and thus acts as a gravity aligned gyroscope.

If interested in flying, then there are various organisations which offer many advantages and cheap insurance when flying larger aircraft. In France, where models are unlimited, there is a flying model Concorde with four miniature jet engines - real miniature gas turbines.
Larger model helicopters and aircraft are now using jet engines, but they are rather expensive.

The ultimate extension of the model aircraft is the twin jet Cri-Cri. (F-PZPR.)

Whether you go further and build your own, or just use the micro helicopter, like all helicopters - they need three things; practice, practice, practice.

This is a piccie of the six planes of movement, (from my boat design page).
Don't expect such complete control from the micro helicopter.

The micro helicopter exhibits a nice dollop of heave, excessive but controllable yaw, almost zero surge, sway, pitch or roll.
A pretty damn good balancing act if you ask me.

Surge can be improved with a little weight on the nose. See also racing, above.

Repair.

No, it is not a disposable item. - Only a decadent prat would think such.

For maintenance, I've applied one drop of oil to the small hole half way up the main shaft. Just one drop of very thin oil to the lower half, to take the upthrust on the main drive gear. Also a drop on the main rotor gearing.

I have used computer controlled high tech radio control gear for many years and still do, yet the micro helicopters' incredibly cheap standard two channel transmitter is perfectly good for the job. I cannot fault his very cheap, yet very effective unit. There is no need to improve upon it.
If it ain't broke - don't fix it.

The front of the legs may break first. Mine did - a tribute to the rest of the machine.
The first thing to break is the forward skid, so use some hard epoxy or filler to strengthen the join forward of the front skid brace, and smooth the epoxy into a lightweight, but strong fillet. This keeps the front of the skid from bending too much and breaking too soon.
Tip : I would recommend adding thin plastic side leg addition BEFORE the original ones break, or at least when the forward parts break off, as the next step is the cross support arms, so anything which strengthens this area is recommended.

Rebuilding the helicopter legs is done easily using a piece of discarded plastic. I tried many methods, but the best was the plastic lid of a tub of potato salad, although a pop bottle is just as good. Although thin, this was thick enough to be strong if used sensibly. Using small scissors, cut a pair of thick skis similar to the original skids size, but deeper for vertical strength. Glue them in place onto the sides of the remains of the old skids. I used 5 min epoxy and laid the machine on its side as they dried in place. This broke, so I resorted to ordinary contact adhesive which worked better. When positioned, these vertical slivers of plastic make strong skis which are very thin when looking down from above and therefore support the helicopter perfectly well with minimal drag. If your plastic is too thin, then simply stick two pieces together for strength. Try it with one piece first, as a second piece can be added later. Every micro gramme saved is good for the helicopter.
Another option is to use small drinking straws as skids, as they can be glued and tied alongside or under the remains of the skids. Slitting the straws before gluing in place tends to weaken them, so keep them as standard tubes. Although they may look big, they are very light and offer no unnecessary drag to the helicopter aerodynamics.
A third option is of course, 'cotton buds', the lightweight plastic tubes with super safe cotton tips and are almost made for the job. The cotton reduces spinning on take off, the skids slightly larger and therefore offer better landings. The tips can be bent up if needed for skid landings.

If one of the inner arms or struts is broken, then use a small dab of hard setting epoxy, or to replace an original section, use some 'plastic metal in a tube' or car body filler as this is stiffer.

My Mk 3 set of legs were a little larger than standard, built from a piece of fine piano wire from a model shop. A short length of this springy wire, slightly thinner than a dress pin cost 40 pence. The wire was first cleaned with fine abrasive paper, although a scouring pod will do, so the solder would take. The lower skid wire was then cut oversize, the cross pieces shaped then soldered to make the framework. To hold the cross pieces in position while soldering, place one end in blue tacky office putty. The finished frame had the skids trimmed to size and the fronts bent upwards.
The framework is then epoxied to the remains of the helicopter after the undercarriage stumps were cleaned up.

Piano wire undercarriage can also be used for the larger helicopters. Making a wider undercarriage can make landing easier and safer. Wide undercarriage can save rotor blades. Just thin piano wire from model shops and good soldering. Never use very strong piano wire, as it must be ultra light weight and spring easily, - just enough to take the weight of the helicopter and a heavy landing, but no more, as the under carriage must always bend before anything else on the helicopter.
Always add a drop of epoxy and foam to the ends of the skids top make blunt ends, as they may otherwise damage the eyes or get stuck in the carpet or curtains.

My circuit board has failed: I suspect the transistor controlling the power to the main motor has burnt out. I will be desoldering and replacing with one from a similar trashed helicopter, until I can find out what transistor is used and this will then be notified here. They usually cost about 50p, but knowing which one is the problem. Until then, I recommend you superglue a little aluminium heatsink over both power transistors on the edge of the circuit board to help keep them cool. Part of a meat pie or other thick alloy foil will do, the larger the better and in the cooling airflow. If anyone knows the correct item then please email. It's the small black box with two legs one side and one leg the other, marked 'Y1'.
To make replacement easier, I have desoldered the transistor and fitted three wires to the circuit bard, so that any replacement can be kept in the cool air and have a heat sink. I have tried a few transistors, but without diagnostic test gear, it is a bit hit and miss. At least the transistors cost only 50 pence each. More later.

The larger helicopters.

If you have a few friends or a club using such channels then always make us a set of clothes pegs marked with each channel, clipped to a bamboo pole with a wind marker, so that only those having the peg can fly, and return it after use, so no one crashes.

If using the larger, outdoor electric helicopter, the batteries are usually six AAA NiMh of about 650 mAh rating, These are easy to buy and a couple of spare packs freshly topped up before setting out for your park or municipal golf course is highly recommended. Making the battery pack connectors is a minor problem, so you will have to buy new connectors and buy enough for all the packs, and to modify the charger too. The easiest connectors are the simplest ones, and by fitting the male and female connectors as suitably matched pairs, then there will be no chance of incorrect connection.
It is possible to buy racing or high capacity batteries and using the best racing batteries, it is possible to have longer flying times.
Older phones may have AAA NiMh batteries and can be recycled to make spare battery packs. If buying new batteries, ask for the tagged ones, and these make soldering up packs easier. Tagged batteries gave easily soldered metal strips spot welded to the ends of the batteries. foe making your own battery packs, see my 'batteries' monograph on this website.

It the helicopter can handle the extra weight, or you wish to fly fast forwards, then the cockpit can be removed and six AA NiMh batts can be mounted on the front, and slid back and forth until the helicopter aligns slightly nose down when held by the stabiliser bar. This should give up to five times the battery capacity, and flight time.
It is possible to make up your own quick connect battery connectors using parts from old computer hard drive power connectors or car accessory spade connectors. Always polarise and sheathe the connectors. I prefer to scavenge from old hard drives and the corresponding 'Molex' connectors. )

Tip : The tail rotors of the larger helicopters use gearing and this is often poorly meshed. So remove the motor cover, then the motor retaining screws, widen the screw slots, then reinsert the motor, and mesh the gears closely before tightening the motor screws. This will then last much longer and be far less prone to trip the gear teeth. Also check the mesh of the main rotor gearing and adjust if needed. Add a drop of light oil to the gears.

Reworking the larger helicopters to three or more channel use.
After a quick look around the local model shop and the more sophisticated electric helicopters costing ten to twenty times the cost, then it's time to get sensible.
The expensive helicopters may have many advantages, but not that many over a 25 pound budget helicopter.
The simplest upgrade is to fit 27 Mhz or 35 Mhz four channel radio control.
The original receiver will not be suitable, apart from may be a reworking of the motor controllers, but this is unlikely and usually an evolutionary dead end.
Three channels are needed for full control, plus extra channels for optional extras such as cameras and such like.

If taking larger helicopter flying seriously, then it is possible to replace the transmitter and receiver for a system with more channels. This will depend upon the country, but at least three channels are needed for a helicopter. Such a helicopter will have a four channel micro receiver, two motor controllers and perhaps a servo to vary any pitch control if modified thus. The latest modern transmitters have up to ten channels and computer assisted mixing and settings.

The modern micro receivers are incredibly small, as are the motor controllers and servos. But they do cost a lot of money. The biggest cost is the transmitter and receiver pack, preferably with just one small servo, as this reduces costs. The add two DC buggy controller motors, one with a larger current capacity of the larger motor and the smallest for the tail rotor. A micro servo will probably be too feeble for moving a battery pack.
For example, it is possible to 'mix' the pitch servo with the tail rotor to give extra speed to compensate for tilting the helicopter forwards, and vice versa, to make control particularly easy.
It is possible to buy many budget items, but not receivers. Be careful when buying micro receivers as some are poorly made and always buy good quality, or the recommendations of fliers. I bought a micro receiver for 12 quid and it was appalling in both range and signal decoding. I then bought another for 20 quid under recommendations, and it is excellent.

It is already noted that the main problem is the lack of forward pitch control to adjust forward speed and hovering control. This can be done with minimal weight by sliding the battery pack fore and aft, to modify the pitch angle of the helicopter. This is easily done using the battery pack on a sliding support or to suspend or swing the battery pack such that it can be moved fore and aft. The battery movement is easily controlled by a standard micro servo. Preferably include a spring link to prevent damage to the servo mechanism, should a crash occur and the weight of the battery should shift with force.
The battery is positioned for perfect vertical shaft alignment, when hung from the stabiliser bar, then moved fore and aft to give about 15 to 20 degrees nose down and nose up for fore aft control. Ideally the battery should be mounted to offer minimal drag both forwards and from rotor wash.

If such as system is made, then I recommend you buy a few more helicopters for spares, and perhaps start making your own blades and looking for a more powerful motor. Carbon fibre blades cost about a tenner, but do not suffer crashes gladly. Such redesign is evolutionary rather then drastic differences, and thereby allow a fully new electric helicopter to be made, if the important items such as the main gears can be sourced.

The money spent on larger helicopters can be partially recuperated if fitting a rubber mounted digital camera using the fourth channel and taking power from the batteries. Then taking pictures of peoples houses / boats farm / etc. from the air on a good day and making yourself available to architects and other builders who may need aerial views before and after building works. They can sell from 10 to 30 quid if done really well and pictures framed or sets of pictures burnt onto a CD. Get permission first. To keep the batteries from draining too fast, the fourth servo has two positions, one to switch on the camera only when needed, and the second position to take each exposure.

Going further.

Now is the time to buy a 99 pence rubber band aeroplane and try some aircraft modelling.
This will allow much longer flight times and greater control.
Indoor flight is the province of the most highly skilled aircraft builders, who employ some incredibly esoteric skills and materials when making the most minimalist flying machines. If you thought the micro helicopter was light, then you have a surprise in store.

With the remains of the helicopter, the reader already has all the desired technology, and the rest costs just a few pennies, but increasing levels of skills. Some even make micro gramme ornithopters (flapping wing aircraft.)

Remember that the radio kit is for indoors use only, so any outdoor stuff will need close control, otherwise it could fly away into the distance. Just set up the helicopter prop, without the tail rotor (unless you can turn the tail motor into a control servo, see below). Trim the aircraft to fly long gentle circuits so that more throttle it will rise and less throttle it will glide back down.
As the 99 pence design also gets broke, gradually build your own aircraft to see what can be done. Bamboo is amazing, second only to carbon fibre.
The best fun planes (or surveillance devices) would be to use the helicopter components in a small aeroplane for slower, more stable flying, although hovering would be almost impossible unless a light headwind.
A small bamboo or carbon and foam aeroplane is perfectly feasible with about three times the span of the helicopter blades. You may be able to use the tail boom.

A two channel plane is not going to be easy to control so will need to be finely tuned to fly straight and level at just over half throttle. Altitude can then be controlled by throttle, with neutral flight at just above half throttle, decent by throttling back, and climbing done with full throttle.
It is common aircraft practice to point the propeller downwards by a couple of degrees to ensure the wings have the correct angle of attack. If using a large diameter prop, then the prop is also slightly angled to one slide to contract the torque reaction.
An aircraft using just two channels will need to have some dihedral for stability. Dihedral is where the wings are angled upwards towards the tips, rather than horizontal like other aircraft. Dihedral ensure the natural tendency of the aircraft is to fly level, and when used with a rudder, to fly into wind.
The main motor can power the helicopter rotors as a large propeller, or a smaller item carved from hard balsa wood or carved from polypropylene. (See my web page on wind tunnels; making props.)

The left - right control is problematic and may need a simple ruder which allows the plane to make gentle turns.
Using the tail motor for direction is very difficult. The simplest is to have the tail rotor point mostly backwards, but at a slight angle to reduce its effect, and then compensate with an angled rudder. Thereby any difference to the tail rotor speed will deflect the tail left or right to compensate for the angled rudder. If any failure of power, the plane will then turn into a spiral decent if this is built and trimmed skilfully.
Suspend the almost finished aircraft on a piece of string, then use blue tacky office putty to position the tail rotor relative to the angled tail rudder to give a neutral yaw at mid position on the control box. Check by moving the aircraft though the air or by gentle blowing, to ensure the yaw (rudder) control is effective. Then mark and use contact adhesive to hold the motor in place.

Here is a picture of one of the smallest servos I know, and at 1.7 grammes, is far too big and heavy for the micro helicopter control system.
Turning the micro helicopter tail rotor design into a rudder servo is difficult, although making a voltage controlled, micro servo, matched to the rear motor power drain or voltage can be employed for left - right rudder control. Use a volt meter across the tail rotor motor to check your device.
Making a lash up with the standard tail motor is too much weight for me. I'm designing a solenoid control acting on a lightly sprung metal leaf spring such that the power applied will decrease or increase and turn the rudder left or right. (I'm presently playing about with miniature solenoids from micro relays and adding my own little variations to give adjustable movement, as opposed to the complexity and weight penalties of servos, which would not work too well with the present system. Solenoids cost pennies to make or from local electronics stores. Thermal operated bi metallic strips are also an option for the micro helicopter system.)
The best I've seen is a small wire coil wrapped in a compact ring about a drinking straw, and just outside this is pivoted a arm swinging passing inside the coil. Inside the coil is a magnetised iron arm such that when the neutral power to the coil tends to pull one way, - but as the is connected to the rudder with is centralising force then it will lie straight when in flight, and varying the current will cause the rudder to effect less or more sideways power to control the forwards direction by the rudder. Such a coil can be made from a bout 50 turns of fine wire, similar to that used by the connection to the micro copter tail motor wires.

To make micro aircraft wings, use off-cuts of blue foam from building sites and make a simple hot wire cutter for pennies, to cut wing profiles and basic fuselage shapes with minimalist weight and reasonable strength. Delta wing shapes are also possible - so check out the model shops and magazines for more ideas. (See also my composite webpage and model aircraft web page - diy hot wire cutters.) Don't forget the reflex if building deltas.

The standard helicopter lithium polymer battery takes a fair old hammering, so don't expect it to last long in duration or lifespan. To add greater endurance, the batteries of old cell phones are often 3.7 volt lithium polymer, so can add endurance to a fixed wing design. The standard remote control should also do the job for charging a 3.7 volt Lipo cell phone battery, although the recharge will take longer. (Many shops sell 4xAA cell emergency cell phone chargers.)

An aircraft of this power is just about capable of carrying a micro camera and offer short range aerial radio TV or stills photography, but the range is the main limitation. I have a mini key ring digital camera which may well end up in the sky, set to take a photo every 20 seconds, preceded with a 5 second flashing LED to warn when to get into position.

If you live near a large pond or lake, then another option for old helicopter kit is to make an ekranoplan, a flying ground effect craft, similar in design to that of Dr Lippisch.

Summary.
When I was a kid, a toy helicopter was a static item. What I now fly would have simply been science fiction.
We live in a world of marvels and the science fiction writers are probably the true arbiters of what will happen in the future. The standard micro helicopter is a modern marvel, the same way the transistor radio was forty years ago.

Always enjoy your toys, no mater how technologically clever they may be and whatever age you are. Don't be like the many stupid and often dangerous 'prats' who mess up the enjoyment of so many others. Always fly with common sense.

Note : If flying in public areas, make sure you have permission, or at least look for any 'no flying' signs first. If in the anally retentive western world, you may well need insurance to cover you from prosecution in an incredibly litigious society. (You could be sued by any prat if you upset them or even touch them gently with the helicopter and cause such prats any 'undue stress'. A woman spilt hot coffee on her lap from a take away and sued and won a million dollars, as the coffee was hot. Yes, we live in 'Prat Land' in the western world, where lawyers are now mainly parasites.)

NEVER encourage your pet cat or dog to chase the helicopter, as this only reinforces its desire to hunt birds in the garden and parks. Like dog shit and barking all night, it's the owners who are ignorant.
A vast number of Robins and other garden birds are getting closer to extinction simply due to household pets and ignorant owners. Please don't be a prat.
Look all around before flying. - Glider pilots are told 'all clear above and behind' before launching.
Don't fly near roads or where you may be in danger.

Have a better, lawyer free day :)

Loads of other stuff on my website.

J.P.

Fight for your freedom - say no to 'politically correct' prats and the plague of parasitic lawyers. - Always vote to keep lawyers far away from politics.
We all deserve a much better world.

Always try to improve society rather than just take from it. Until then, lawyer stuff. Copying or duplication of this material is prohibited without written permission of the author. No one should read nor act upon this information. The content is for information only. No responsibility is accepted for any damage or any injury caused by the above information. Errors and omissions excepted. No-one should try anything in the modern world without reasonable abilities and know that injuries can ensue from the materials, tools and from testing.
Have a nice (lawyer free) day.

Copyright (C) J.Partridge. 2007.