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Spring 2007 Newsletter

  Just how reliable is your Radio equipment?

Continuing on from last month, I’m moving on to the exciting area of RX and fairly basic radio installation. A lot of us are guilty of relying on just a lump of badly installed foam to drop our electronics into and when something does go wrong blame the poor old Rx or X-tal for being the problem. But hang on a minute how careful are you with your Radio’s installation and maintenance.

Did you ever notice how it’s usually the same people that are chasing an elusive glitch or shout “Radio” as they fight to gain control of a wayward model? Often this problem seems to pursue the same individuals throughout there flying career. Time and again I’ve witnessed this to the point it is almost comical as you are just waiting for something to happen...

So what can we do to help avoid this dangerous and expensive situation happening to us? Well there are a few basics. There are lots of little things but added together will greatly reduce the chances of you becoming a victim. OK so enough waffle.

 First I would recommend buying the best equipment you can afford as the cheapest option often ends up way more expensive in the long run. (As Bob reminds me “the poor man pays twice”)

Fit equipment suitable for the purpose required, servos, battery, switch wiring servo horns linkages and battery must be suitable for the application.

Try to avoid any form of vibration reaching any part of your radio, not just the RX but the switch, servos, wiring, connecters, battery etc.

The most common problem I see is people not installing the servo grommets, ferrules properly. The ferrules usually being installed upside down. (Look at your manual) The design is supposed to isolate the servo from the airframe vibration. Notably some servos have a reinforcement lug (JR being one) If you use the metal plates as supplied with some kits the plate hits this lug it transfers vibration directly to the servo. So much so that Macgregor the UK JR importers will not warrant servos with marks on the lugs.

Store your equipment in a warm dry location. Keep your radio equipment dry; carefully wipe any fuel residue, moisture etc off exposed servos switches after every flight.

Extend your Tx aerial one section when working with the Tx switched on. (Prevents the output circuit being damaged)

Ensure your batteries are freshly charged before coming to the field. Fast charging at the field often results in a lower capacity as the charger trips prematurely when charging at high rates. It also reduces the batteries lifespan considerably. Slow overnight charge is best 

Batteries need regular checking preferably with some kind of load check or cycling to confirm they are working to capacity.

Switches are cheap if in doubt or getting old change them, they don’t like fuel/ moisture either, so think about its location, is it going to get an oil bath every flight?    If possible vibration isolate your switch. 

Wiring, do not pull/ stretch or kink servo wires etc, soft mount the wires where they cannot chaff. Secure servo plugs physically from coming apart. Properly support wiring but allow for a little give. Run the RX  aerial as far as possible away from the other wiring. Locate the Rx/gyro’s etc  as far away as possible from speed controllers and the like as they produce a lot of electricial ‘Noise’. The same applies for spark ignition models.

Helicopters need additional care as do larger aircraft where high levels of vibration are experienced. The aerial exit point on the RX is prone to failure, The Rx plugs and X-tal need to be secured. Ideally the aerial is supported along it’s length. (see piture of my method) Helicopters try to secure your wiring softly, preferably by not using cable ties as they do tend to chaff wiring but worse still in a crash will cut/break the wiring.

Servos, especially Digital will fail prematurely with stiff or over travelling linkages, so ensure every possible step is taken to reduce friction and binding. Beware some Radio’s will over travel linkages when using mixing. So check. Another example is the throttle trim/servo cut settings often do this and need to be set properly.

Here is another little Gizmo I really like. It is just as effective in a Helicopter or Plane. It’s costs about £3 and is rugged but soft Neoprene. It is easily mountable almost anywhere. As you can see the aerial is properly is supported at the Rx exit point by the ‘fuel tubing’  which is attached to the side of the Rx. This continues down to the aerial tube at the helicopter U/C struts. The X-tal is taped in or secured by the packing depending on it’s position. The servo plugs are secured 100% by the 1mm piece of carbon rod and little elastic band.

With a Rx with top entry plugs you can carefully wrap the Rx wallet so that it sits over the wiring securing it but under only minimal tension by keeping the pull down strap to the middle of the wallet.

I’m sure there are plenty things I have missed but the above gives you an insight in how to go about getting the best reliability from your Equipment.

An intelligent but expensive glow driver.

Never again will you have to show up to the flying field with a dead glow plug driver.

Barneys Crystal Ball

How would you like a cheap seven channel ‘multi-mode’ Heli Aero Glider Radio system with a 5mile ground to air range that requires no crystals, no frequency peg, is totally glitch free with electric models, has a failsafe system built in. Virtually impossible to shoot down, even recognises what model you’re selecting preventing wrong model selection, has low latency compared to radios costing five times as much and even stops digital servo’s buzzing due to its increased signal Speed. 

Tall order and light years away?..Your wrong 

It’s here now..right now.

The Spectrum DX7. £239 buys you a 2.4 Ghz spread spectrum technology Tx with 20 memory radio that includes 4 digi servo’s using a JR case and sticks. And it’s legal to use in the UK

The future is here now! Just follow these links to see what everyone in the ‘Know’ is raving about 

http://runryder.com/helicopter/t298150p1/?highlight=DX7

https://www.skylinemodels.co.uk/acatalog/Whats_New.html

I’ve been following the testing and the reviews of this equipment over the last few months. For heli flyers the pitch curves/throttle curves are 5 point BUT have a smoothing function to smooth them out. The Swashplate functions are Remapped for super accurate control with CCPM mixing with NO interaction. Combine this with all the advantages of the above. There is only two drawbacks, Its not backwards compatable with any 35mhz Rx’s and only available in a 7 channel version but do note it operates all your other equipment just fine. The reason it’s glitch free with electrics is the interference created is between 200-400Mhz which effects 35Mhz transmissions BUT not 2.4Ghz (microwave transmissions).

This new technology will also allow things like in flight model data logging, video downlink capability and the like in the not to distant future. This is only the beginning, as there is already a 16ch system being developed.

OK here is some other stuff from the sharp end 

Electronically controlled Flybarless System

New Heli Technology that is already available and being further refined is a virtual flybar system whereby gyros stabilise the Aileron/elevator functions without impairing model response. In fact accuracy is enhanced. Other benefits from removal are lighter overall weight and a large reduction in aerodynamic drag.

That means higher power to weight ratio and increased duration combined with better accuracy and a tuneable response via your Tx or a Laptop.! 

Yet more stuff as many of you are aware is the use of lipo, lion batteries particularly in high performance planes, Jets and helicopters for Rx power. Don’t dismiss this technology lightly as I reckon it’s here to stay. Lighter weight with more battery capacity allowing redundancy to be built into battery packs etc. Currently you have to use a voltage regulator to drop the voltage (7.4v) from these packs to anything between 5-6 volts for use depending on the servo used. There are already a few specialised 7.4 volt servos around but Rx’s are not designed for this voltage as yet.

I’ve been running a regulated system in my Dyna-X helicopter for a year now that uses a 7.4v KO Prop 2123 servo for the pitch function with 9Kg of torque and transit speed of .06 sec..Thats around 4 times quicker and 3 times more powerful than a Futaba 148. The way it does this is there is a 4^th power lead on the servo to take power before it enters the voltage regulator.

The regulator I am using ‘Fromeco Arizona’, has two separate voltage outputs, and the current is  supplied via a 2 cell 7.4v lipo. The reason for the two outputs is nobody currently produces a 7.4v/6v  tail servo so requires a nominal 5v supply or it will burn out prematurely. The second output is adjustable 5-6v for your main flight servos. In my case they are 4.8 to 6v capable and choose to run them at 5.6v.

Running a regulated system is actually noticeable in flight, with a helicopter anyway. There is no drop of in voltage like you get in a conventional system under extreme load or as the battery voltage is diminished.  With a normal system fresh of the charger you get around 5.5v to the servos initially but it quickly tails off especially under load. By your 2^nd/3^rd flight system under high load you’ll be very lucky to get 4.8v at the servos. With the regulated system you get no voltage drop and remains at the set voltage throughout.

This is especially noticeable in fast backwards flight/tailslides with a helicopter as the Gyro tail servo have to work very hard to maintain heading.  I have also now fitted a regulated system to my Raptor 50 with good results 

Another benefit of a higher input voltage is it requires less capacity to achieve the same results increasing flightime between charges or can be used to reduce weight.

Even the new (or is it the now outdated G3 2048 bit PCM system?) Futaba flagship Tx sets, the 12/14Mz are using lipo batteries

Barneys Equipment views

Since it’s ‘That  time of year’ and 90% of you can’t face the cold and damp I though I would do a few mini reviews to keep your enthusiasm fired up and keep you in touch with reality. There is just so much innovation going on that equipment is evolving on an almost weekly basis.

Fuel for thought!.. I’m sure some of this will generate a little chuckle or two from the older hands amongst us! First off I’m going to touch on that exciting area. The fuel pump.

Over the years I have used almost every kind conceivable from electric pump through to hand pumps, and even the ‘Humble’ fairy liquid squeezy bottle!

Believe it or not but each type has there advantages/disadvantages but for me my number one consideration must be 100% reliability, that combined with light weight and no leaking.

The  Squeezy  liquid bottle. Very cheap, quick to fuel, especially if you’ve got big ‘hands’ The draw back is it has a very small volume and very messy to refill...Great for little diesel engines and the like that require little fuel for a days flying..

Garden Fly-spray, the pump up type. In use this is a pretty nifty piece of kit, but don’t use it to spray the Roses afterwards. It fuels very quickly and if you choose carefully by picking one with a large top is easy to refill. Drawbacks are the design is usually rather tall with a high centre of gravity so falls over easily. Nitro/methanol also damages the seals after some tome causing it to leak or malfunction completely. Of course that’s only an issue if you haven’t already broken it with it flailing about in the back of the car in your hurry to get to the field!

Electric pumps both separate and power panel pump. ‘For the lazy amongst us’ this is the preferred option. I’ve still to find one that doesn’t leak though. They fuel well  ‘BUT’ do require a battery to power them which is a big negative, also no use if you wish to travel light. I’ve still to find one that operates under the SAA noise limit.

Hand pump, The squeeze bulb type. Usually sold for use with large petrol models. What you do is orientate the bulb upright or inverted to fill or empty as required. Very reliable, but in practice a bit dribbly and messy. These are often supplied with a low profile one gallon red plastic container (Mostly used for boats fitted with a small outboard motor) The fuel tubing supplied is rather stiff being designed for petrol use. Great for petrol models but somehow just not cutting the mustard with Glow fuel.

Geared hand pumps (most common type). Light, quick to fuel and can be used direct from the fuel jug. The easiest option is to fit a purpose designed fuel bottle top or adapt your own and just swap the pump over from bottle to bottle. Reliability is good providing it is used with a little care. Most are prone to leaking though, and if forced you can shear the handle off or strip the gears. Overall pretty good but they do seem to deteriorate with time especially when exposed to large amounts of Nitro.. on the plus side they tend to give plenty of warning before failing.

Non geared hand pump. My ‘new’ favourite. The Dave Brown Six-shooter. This pump looks different and is rather quirky in use being a departure from the norm. In use it has a very clonky feel that does take some time to get used to and would also benefit from being hard mounting where possible. This pump works by a couple of large knobs squeezing an internal bladder (Large diameter tube) delivering about 0.6 oz per turn.

A spare bladder can be purchased at very reasonable cost and should the need arise be replaced easily at the field. It is a little slower to fuel but has so far proven to be 100% reliable without no leaks. It’s definitely not for everyone though, but if you can live with the unusual feel it is well worth considering.

BTW You have look at my ‘SIX SHOOTER’ in the picture of completed Fuel tote box

*Check the Archive page for old News.