The Cyber Parachute Surfer.
Page two.

Please read page one first.

Upgrading the Cyber-chute.

April 2007,

This page is pitched at the RC novice. Experienced RCers may already have the gear and hopefully the know-how.

This is an Australian site, prices mentioned are either Aussie or US depending on where I found stuff.

Currently one AU$ = US$0.81 , prices are just a guide so it doesn't matter too much.

As I stated on page one – a well designed, well tuned paraplane could be the perfect RC model for beginners – unfortunately the cyber chute has it's failings.
Out of the box you are likely (probably certain) to have one of two problems and possibly both.

The first is inadequate motor power (and duration). Some will climb using the stock battery but mine didn't. The clones are supplied with nicad batteries which are very 'last century' technology. You can expect about four minutes flight duration.

The second problem is a sever roll to the right. The more power you have the worse this gets. If you have inadequate power for climb the roll problem is less sever.
My transmitter didn't have adequate yaw (rudder) trim to compensate. If you do manage to launch and trim it - the model will go left once you reduce power. This is not good for a beginner to manage.

Refitting any RC model is expensive, if it is the first one you're doing. The second one is much cheaper because you already have the transmitter, charger and parts you can borrow from earlier models. With only a motor and one servo the cyber-chute refit is likely to be cheaper than any most powered RC aircraft.

There are budget parts available, they are usually a bit heavier but if they work properly could be quite good value.


The cheapest (but not cheap) and easiest improvement you can make is to put in a decent battery. Even nickel-metal-hydride batteries (twice the capacity of ni-cad) are pretty much obsolete and hard to find. Genuine sky-surfers had an optional 1100 mAH NiMH pack but I doubt you can buy one now.
Everybody uses Lithium polymer (LiPo) these days. They aren't cheap but the prices are coming down. These model don't fly well if you reduce the weight so ideally you want a LiPo which is about the same weight as the original - that means around 2200 mAH and 7.4 volts. A good quality battery will set you back US$60 or so but you can get a budget model for $20. I have no idea how good the cheap ones are. A charger will cost more than that. Mine (a swallow) was $100AU you can possibly get sometime for half that. You should also get a balancer (already built in to some charges). Many chargers (like mine) run off 12Volts so you need a decent 12V supply to drive them (eg a car). A good battery will probably fix problem the power and duration problems.
There is a catch here – the battery for a stock model need to be around 7.2V so you can only use two cell LiPo (7.4).
The problem is if you decide do a complete upgrade you may want to use a 11V battery, most people do.

The Chute.

The clone chutes are not particularly well made. Fortunately they fly better and last longer than you might expect. There are currently no alternatives that I know of. Genuine sky-surfer canopies are no longer available in most parts of the world. I think I got the last two to leave Japan. I have experimented with using kites but they won't fly well on a stock model. It is possible a kite can be made to work with a fully upgraded model - it is research in progress. Kites have more drag than the plastic sky-surfer chute so performance will be reduced. This is offset by the convenience of a cloth chute which can be folded and does not require spreaders – stay tuned for kite progress.

The sky-surfers use a plastic chute compared by some to shopping bags. The rigging is unusual. Most paraplane foils I've seen have four rows of lines which terminate at two attachment points. Typically one group of four lines is attached to every second rib.
Parafoil kites usually seem to have three rows.

The plastic chute only has two rows. One set at the front and the other about one third back from the trailing edge.
All other chutes I've seen are cloth only. The surfer chute alone uses soft foam ribs and plastic tubes spreaders (AKA stiffeners) – this allows them to work with only two rows and allows for a thinner lower drag profile.

The lines terminate to four attachment points not two.

You can easily convert a surfer to use a two line chute and you can also convert a surfer chute to work on a two line model.
You can also do both and fly a surfer chute on a surfer in two string mode. This changes the flying characteristic.

I should also mention the canopy area has to be matched to the weight. A bigger chute is not going to work nor is dramatically reducing the weight of the stock model.
When the load on the chute is too little the gondola becomes unstable. This is mainly when powered – models which are unstable during powered flight will often fly quite well in the glide. They will also fly better when turning because the line tension increases.

The full upgrade.

Other items you may want to upgrade are – the radio receiver, the servo, the ESC (speed controller) the motor and propeller. The bad news is you pretty much have to do them all together. Everything in the stock model is non-standard, probably the RF signal is also non-standard – it is 27mhz which is illegal in many countries.
The receiver, ESC and the servo electronic are on one board. You really have to throw this away and replace it with standard RC parts.

Another hack which has been done is to add an extra control channel (and servo) to alter the AOA (angle of attack) of the chute in flight.

The radio.

I usually use JR gear for it's long range but it is expensive. Budget receivers (RX) can be as low as $20Aus but quality and compatibility are unknown to me. Remember control failure could result in the loss of the model (upgraded and now worth hundreds of dollar), so it might be worth a few extra dollars for a known brand. I've used GWS ($32 for 6-channel) with no problems.
You only need two channels to fly the cyber-chute but you're unlikely to find anything less that a four channel RX.
A common fantasy which seems to be shared by most of us - is to fit the model with a camera – some extra RC channels are handy for this.
Most FM RXs and transmitters (TXs) are compatible. JR, GWS and futaba will all work together but some may need channels reversed.

I have a basic JR 6 channel TX which works fine but I had to hack it the move the throttle to the left where I wanted it.
Forcing ozi pilots to use a different configuration to the US is a major gripe of mine.
If you have a helicopter style remote this could be handy because of the built in fixing functions – these may be able to compensate for torque steering (ie the roll problem). I don't have one to try it. There are also separate heli tail mixers that might work. I have one but I'm not planning on trying it.

The motor.

It is not essential to replace the motor but pretty much everyone does. Brushless motors are lighter, more efficient and some have enough torque for direct drive. On the other hand keeping the motor lets you use a cheaper ESC and lets you use any two cell LiPo you may have bought for it.

The most promising fix for the roll problem mentioned early is mount the motor so the thrust is off axis by about four degrees. This is hard to do if you keep the gearbox so direct drive brushless make a lot of sense.

Choosing the correct motor is difficult. You need to match the speed (RMP per volt) and have enough power. For direct drive you will need an “outrunner” type motor. AXI is one popular brand, there seem to be cheap motors about ($15) but I don't know how well they work.

My preferred motor is a CDROM style motor. These don't actually come from CDROM drives any more but use a similar design. I have taken to winding my own.
A single stator CDROM motor should work fine. has kits starting at US$9 but a decent kit with ball bearings and firewall mount is US$26.49. For a few extra dollars you can get a double stator kit. You shouldn't need a double but if you have room the bigger motor should run a bit cooler and possibly more efficiently. I'm using a single for size reasons.
Making a motor sounds daunting but it isn't so bad after the first one. The hard part is working out how many turns to use but I've got some numbers that seem to work which I've shared (see black rainbow page two).
The motor shown here is a double stator motor built from a kit. Winding your own not only lets you choose the number of turns used but also lets you choose between a star (AKA wye or Y) or delta winding. Most commercial motors are star wound most high performance CDROM motors are delta. Both styles work but the number of turns are different.


You can use the stock prop if you want but I didn't. There are three reasons why I changed.

  1. The prop has the reverse pitch to the common props sold at my local hobby shop. This means either it rolls right while my other models roll left or I offset the motor to compensate. Which side you offset it depends on rotation direction. If I offset it and need to replace the prop I will have to match the pitch or move the motor again to the other side.

  2. I can swap props between models.

  3. I have spinners which fit the motors I use – these would not fit the stock prop without modification.

The props I use aren't specially made to be pushers, you just mount them on the spinner to be a pusher. You might be able to find a push-on pusher prop that will fit but using a common prop has a lot going for it.

I'd suggest you match the stock size and pitch if you can unless you have a good reason to change it. Presumably the original designer/builder found this to be the best.

The genuine sky-surfer prop is part number HBZ78118 and is a 9*4 inch prop. That is nine inch diameter and a travel of four inches per rev (less in practice)
I couldn't get 9*4 so I'm using 9*4.5 and also have a 9*3.8 I haven't tried. If you're flying faster (heavy or with canopy adjusted for speed) a courser pitch should work better.

If you measure static thrust you'll find a fine pitch will give you more thrust. Don't be fooled into thinking this is necessarily better. It is like gears in a car – a low gear gives more starting torque but won't go fast.


Your motor needs an “electronic speed controller”. Brushed and brushless motors generally use different controllers though there are a few ESCs which can do both. Brushed ESCs are cheaper and often simpler. I've used JETI brushed controllers and phoenix brushless. Phoenix are good but once again not cheap.
I have ordered an
eWatts Brushless 18A to try out – at AU$24 it is a fraction of the price of a phoenix – this will be tested on the my new black flying thing.

Most ESCs will have some way to configure them. The phoenix ESC can be programmed using the radio TX or with a USB interface – I do the former.
A whole lots of parameters can be set this way. Things like timing, brake settings, current limits etc.
One very important setting is the cut out voltage. You don't want to run your battery flat because you will loose not only motor power but control power.
If you are using LiPo running them flat will ruin them. To avoid this happening the ESC senses the input voltage and when it gets low it cuts power to the motor.
You may have to set the cut out voltage to suit your battery, some ESCs guess the number for you.

The most obvious difference between controllers is there current rating. I'm putting a phoenix-10 (10 amp) into my surfer – this should be enough unless I want to add a lot a weight.


This stand for “battery eliminator circuit”. This might sound strange for something battery powered but it makes sense in that some older RC gear used a separate battery. Ie one for motor, one for radio and servos. All a BEC is is a five voltage regulator (sometimes six volt). All modern ESCs have a BEC built in. Some even have two – one for the motor controller on one for everything else – mainly to reduce RF interference.

In most electric RC aircraft you attach the battery to the ESC, when you plug the ESC into the radio BEC power (5V) is fed to the radio which then routes power to the servos which are plugged into it.

The ESC/BEC is a crude linear regulator, they are inefficient – particularly with higher battery voltages. A separate switched mode (efficient) BEC can be used if required. A park-BEC is one I've used before. If you are just going to run the steering servo you probably wouldn't bother.
Your ESC instructions should give some guide to how much load you can hang off the BEC at different battery voltages. If you plan to use extra servos you may need a separate BEC.


The entire weight of the gondola hangs off the servo. When I built my black rainbow I agonized over torque and side load and bought a fast, grunty, dual bearing hitech servo. It turns out the servo doesn't have to be fancy. A basic futaba 3003 is one type which is known to work.
I was planning on using the hitech in the surfer but found that the spline on the servo was too small to fit the servo arm – the futaba spline fits.

Ted's Hack.

I didn't hold out much hope that there would be an easy fix for the torque steering problem. Strangely only people with surfer clones are reporting this problem so it appeared like it might be that small paraplane flyers would have to live with it.
Fortunately Ted Robinson (who is in our paraplane google group) tried skewing the motor off axis to compensate. I did not think this would work but apparently it does. This could potentially solves a serious control problem and could allow us to fly lighter and also to use kites. Ted's test mod is shown here. You don't need to be hi-tech to contribute to the knowledge base.

If you're interested in this stuff you should join the group.

Fred's Hacks

Fred Garvey posted some notes to the group which I have copied here. Fred has informed me that he hit a snag in that his motors have been burning out rapidly. He puts this down to reversing the polarity to make them spin the other way. (The stock motors did strike me as being a bit small for the job.)

My Hack 1.

Easter 2007.
After sitting on the shelf for almost a year the cyber chute flew again – briefly. It flew for perhaps a minute then lost revs and descended. I'm not sure why it was different to last time but it was. I decided it was time to rebuild it. Seeing the electronics were going in the bin I experimented with running it on three LiPo cells (11V).
It had lots of power for a second or so then the a fin pulled out of it's joiner and the prop struck plastic breaking the cross bar.

After that the motor didn't work properly any more.

So lets see what we have here.
Like most cheap RC toys there isn't really much worth keeping apart from the frame. Some people reuse the propeller but I'm not. Even fewer use the reduction gear. The servo is non-standard, it has no internal electronics and is useless. I'm re-using the servo arm but the spline did not match the hi-tech servo I planned to use so I bought a futaba instead. The electronic s(RC receiver etc) is also useless.

Note the prop shaft passing through the middle of the joiner which hold the fins. This means you can't put a direct drive motor in the logical position unless you modify the fins.

I chose to locate a small CDRom motor behind the joiner. Here I've ground away all the plastic where the motor will go. The motor is recycled from my black rainbow project. The joiner was later secured using a rawl plug up the middle and a plaster-board screw.

The cavity was filled with tissue and the motor tube repeatedly dipped in wax to build up a large blob which was then shaped using hot cloths iron, a cheese grater and any suitable carving tool that came to hand. When I had the desired shape, it was again hot dipped to completely cover the work area (and the floor) with a release layer to prevent epoxy touching the plastic.

The wax plug was made strong enough to prevent being crushed when placed under vacuum.

Carbon fibre cloth was wrapped around the plug and held in place with sewing thread till in was vacuum infused with epoxy resin. This was the quickest infusion I've even done.
Once the resin had cured the wax was melted out and the carbon fibre housing trimmed to size, mounting holes drill then ventilation holes added. The housing weighs 16 grams and is very strong. The motor is skewed about four degrees (CCW when viewed from top) to reduce torque steering problems.

The broken cross-bar is being replaced by a 3mm carbon rod which locks the housing in position. When the bench testing is complete it will be bound in place with cotton and CA – strong but removable when the need arises.

By the way the strange lumps of putty are for flying a two string canopy – the servo extenders are moved back into these holes so they are closer to the COG (centre of gravity).

April 27.

I've had a lot of trouble getting my single stator CDROM motor to work. I replaced the magnets and rewound it several times. It is now delta wound with 26 turns of 28 gauge wire per pole. It works but it is still getting very hot. The double stator motor I made for the rainbow (and now in the black thing) runs cool. I think I will be moving to double and triple stator motors in future.

Anyway it flew. It launch and climbed well on the first attempt but the steering was terrible. My cyber-chutes are both pretty sluggish.

The climb out was very steep and looked semi-stalled. It flew level on less than ½ throttle.

My setup was

  • Servo futaba 3003

  • Motor direct drive go-brushless single stator cdrom.

  • ESC pheonix-10

  • RX – 4 channel GWS

  • Prop 9*4 inch

  • Battery - three cell lipo - 1800mAH flightpower EVO-20 (11.1V)

  • Gondola 480 grams (very close to stock weight).

The canopy was set for maximum AOA – this may have a bearing on the steering problem. The old cyber-chute canopy flew fine on the black rainbow gondola when converted to two string mode. It may be worth flying it on the cyber-chute in two string mode to see how it steers. It may also be worth adding some weight or using a stiffer servo arm.

I'm not sure if I will be doing any more on this. The flight showed the offset motor does work – the model did not torque roll as it used to.
The black thing is almost ready to fly so I will be focusing on that.

If anyone is interested in working with carbon like I do – buying a cyber-chute and replacing parts with custom carbon one piece at a time would be a way to get into it without having to make everything in one go. If you replace the shroud with carbon you could probably increase the prop size to 10 inch for extra thrust.

If I did this again I think I'd totally replace the motor tube. It would mean changing the central fin attachment but would be easier overall.

May Day 2007.

Thanks to Len Martin for taking these photos.

I did some more test flights at Nimbin where I have more space. All launches were successful but the flights were fairly short because the motor is still getting very hot – too hot for me to hold my finger on the mounting screws after landing.
Full power climbs were very steep and stable. It again gave the impression of climbing vertically, I don't think it was but it looked that way from behind.
The steering problem is only when turning left. Right turns and level are fine but left is extremely slow.

It appears the motor offset is about right when using full power but to much on a cruise setting.

I'm also now convinced the giggling/shimmying motion of the gondola in this and other models is a gyroscopic precession problem from the spinning prop. A lighter (carbon) prop would help here.

My Hack 2.

Cheers Eddie.M.

My models page is here and my home page is here.