January 29

How To Fly RC Airplanes Well

It is my experience that most model plane flyers become set inSport Aerobatic Model their ways when it comes to their repertoire of manoeuvers. Once they have managed to reach a level of competence that enables them to fly solo, they tend to settle for a simple selection of basic skills.

Part of the pleasure to be obtained from your flying  is learning how to fly rc airplanes well. This inevitably involves extending ones range of flying skills beyond the most basic ones required to take off, fly  circuits and land again.

Above is a typical follow on model from your trainer type. This plane is capable of most aerobatic manoeuvers that the average club flyer will want to master. Most clubs will encourage newcomers to become solo proficient and to progress to a more advanced level so that they have confidence in the ability of that flyer.

Achievement Schemes

In the UK the model aircraft governing body, the BMFA (British Model Flying Association) run such an achievement scheme that comprises two levels of competence.

The first level is known as the “A” certificate and the test can be performed with virtually any powered fixed wing model, glow/nitro or electric powered. It is aimed at proving to the club that you are safe to entrust a model to without supervision.

The Test

The candidate should also go through the pre-flying session checks, also laid out in the BMFA handbook. Particular attention should be given to airframe, control linkages and surfaces.

The pilot must stand in the designated pilot area for the entirety of the flying part of the test.

He/she must take off and complete a left (or right) hand circuit and overfly the take-off area.

Then fly a “figure of eight” course with the cross-over in front of the pilot at a constant height.

Fly a rectangular circuit and approach with appropriate use of the throttle and perform a landing on the designated landing area.

Take off again and complete a left (or right) hand circuit and overfly the take-off area.

Fly a rectangular circuit at a constant height in the opposite direction to the landing circuit above.

Perform a simulated deadstick landing with the engine at idle, beginning at a safe height (approx. 200 feet) heading into wind over the take-off area, the landing to be made in a safe manner on the designated landing area.

Remove model and equipment from the take-off/landing area.

Complete post-flight checks as required by the BMFA Safety Codes.

Question & Answer Section

The candidate then must answer correctly a minimum of five questions on safety matters, based on the BMFA Safety Codes for General Flying and local flying rules.

As you can see, this is a fairly strictly controlled process and demonstrates to the examiner the candidates ability to handle his/her model to a satisfactory standard and their understanding of the rules governing model flying.

Until this test is completed to the satisfaction of a BMFA appointed examiner from within the club, the pilot is not allowed to fly alone but must be accompanied by an approved competent pilot during every flight.

I’m sure other countries have similar schemes and I suggest it is in the best interest of every model pilot to take and pass such a test, where available, for both theirs and the public’s safety.

More Advanced Flying

As the rookie flyer progresses there will inevitably come a time when the desire to fly more sophisticated models will occur. If the pilot has not advanced further than the manoeuvers required for this “A” certificate then a sense of frustration will arise through not being able to  take advantage of the new plane’s potential.

The BMFA’s “B” certificate is aimed at helping the pilot progress in exactly this manner.

This is a much more complex test involving a number of what can be called “Aerobatic” manoeuvers that need to be practiced well beforehand.

Let’s take a look at what this schedule involves:

a) Carry out pre-flight checks the same as for the “A” certificate.Outside Loop

b) Take-off and complete a left or right hand circuit and overfly the take-off area.

c) Fly a “figure of eight” course with the cross-over in front of the pilot.

d) Fly into wind and complete one “inside” loop.

e) Fly downwind and complete one “outside” loop (a Bunt) downwards from the top (See diagram right courtesy of Dundee Model Flying Club).

f) Complete two consecutive rolls starting into wind.

g) Complete two consecutive rolls downwind rotating in the opposite direction to those above.

h) Complete a “stall turn” either to the left or right.

i) Gain height and complete a three turn spin. The initial heading and recovery heading must be into wind. The model must fall into the spin (NO flick entry).

j) Fly a rectangular landing approach and perform an “overshoot” from below 10′ (3m). This must be recognisable as a baulked landing, not a low pass.

k) Fly a rectangular circuit in the opposite direction to that used in the “overshoot” at a constant height of not more than 40′ (12m).

l) Fly a rectangular landing approach and touch down within a pre designated 98′ (30m) boundary.

m) complete post-flight checks as required in the BMFA safety code manual.

Following this flying test the candidate must satisfactorily answer eight questions based on the BMFA safety codes.

Other Countries Schemes

I know that both Australia and New Zealand run similar schemes but so far as I know there is no such scheme in the USA or Canada.

If anyone knows differently I would be happy to amend this information.

Setting Your Own Standards

Just because you live in a country where there is no pilot achievementP51 low fly by scheme doesn’t mean that you shouldn’t set yourself the challenge of achieving an improved standard. You may be thinking that as there is no set programme to help you, where do you start and what do you practice?

How about adopting the above “B” certificate schedule as a guide for yourself! I can guarantee that if you practice the manoeuvers required for this schedule, your flying will improve beyond all recognition. There is, of course, no time limit and you can practice them in whatever order you prefer.

The implication is that you will improve your flying in a structured way and obtain much greater satisfaction than if you just fly aimlessly around all the time. It will open up the scope for you to include such models as the one shown here or even more aerobatic types. As a result your appreciation of your chosen model’s capabilities and your confidence in how to fly rc airplanes well will also be greatly enhanced.

I hope this post has given you inspiration to set yourself some structured challenges and become a more competent pilot. If you have enjoyed it please feel free to share it with others you think may find it useful.

If you are still in the early stages of learning to fly take a look at my website www.rookiercflyer.com for a comprehensive guide to starting the hobby.

Best wishes,

Colin

 

 

 

 

 

 

 

 

 

January 22

Model Aircraft Insurance

On my website www.rookiercflyer.com I covered in some detail the desirability of joiningRC plane windscreen damage a club to help you learn to fly the best and safest way possible. One of the major advantages of club membership is the inclusive third party model aircraft insurance cover.

I am often asked whether insurance cover is necessary when the majority of model flying is done in wide open spaces with few if any obstructions that could be damaged by our model planes. This is a justifiable argument but ignores the fact that we often fly in the presence of others and there are flyers vehicles parked nearby that could potentially be damaged by out of control models. Just by way of example here is a link to a video showing the aftermath of a nasty rc jet accident that injured at least one person and several models and vehicles.

Not all rc plane flyers join clubs but instead prefer to fly alone on playing fields, recreational areas, etc. that are surrounded by properties and people. Such enthusiasts may claim that they only fly lightweight park flyer types that are relatively safe and incapable of causing serious personal injury.

I would suggest to them that they try to imagine the effect of a plane weighing around 1lb to 2lbs (0.4kg to 1kg) hitting a small child square in the face whilst travelling at around 30 to 40kms/hr. with a whirling propeller at the front. Do they really think that there would be no real physical damage to say nothing about a civil damages claim through the courts?

When it comes to property damage, I can speak from personal experience of an incident in which my car was damaged by an out of control model plane. The damage to the roof was extensive and the cost of repair in excess of £1000. Very fortunately I was at our model flying field and the guy whose plane went out of control was covered by his club membership insurance.rc plane crash into wall

It is not only cars that are vulnerable, sometimes buildings are close enough for a wayward model to find it and cause damage. Even a trainer like the one on the right has sufficient momentum to cause structural damage.

I’m not sure what material the building shown here was constructed from but it certainly didn’t resist the onslaught of this wayward model.

Things are going to get a little gory since we need to consider what happens when model planes come into contact with human flesh.

Again, speaking from personal experience, I can assure you that very seriousRC plane Facial damage injury can be caused by such incidents. I have included a photograph here that may upset some of a more sensitive disposition but I make no apology for it. Such injuries, especially when sustained by innocent third parties, can be very serious. The unfortunate gentleman in this photograph was hit in the face by one of the new generation drones that are taking the model flying fraternity, and others by, storm.

Such superficial injuries repair quite quickly, even though they may leave permanent scarring, but more serious injuries can by fatal. Never underestimate the enormity of the consequences of the flying machine you are responsible for.

The next picture, although a reconstruction for the purpose of Personal damamge by rc planedemonstrating the point being made, represents exactly what can happen if a large model collides with a human being.

Such an incident happened at our club here in Spain when an innocent bystander was hit directly in the stomach by a large petrol engined model that suddenly went out of control. The pilot tripped over and fell on his transmitter driving the throttle open.

The injured man was hospitalised for several months and it was touch and go whether he would survive in the early stages. His stomach was ripped open by the rotating propeller and it took several hours of surgery to save him.

Uninsured Implications

We need to be aware that the primary function of insurance is to protect the insured person in the event of a claim being made against them following an incident.

Imagine that you were to be found responsible for an incident and you were not insured. You would be personally liable for any damages or costs awarded under the jurisdiction of a civil court.

The implication of this is that you could stand to lose everything, an eventuality that has actually happened on more than one occasion.

Becoming Insured

At the risk of becoming repetitive, I can only propose again my suggestion that the best way to do this is to avail yourself of the inclusive insurance cover associated with club membership. From here on in I am going to concentrate on the two largest national governing bodies for radio control model flyers through which such insurance is readily available either as a club member or as an independent flyer.

For those of you for whom club membership is not practical, some national governing bodies offer cover for “country members” that can be purchased separately.

In the USA this is the AMA (Academy of Model Aeronautics) whilst in the UK there is the BMFA (British Model Flying Association). Other countries have their own equivalent organisations. I suggest you Search online for the one that governs model flying activities in your country.

Insurance Through The AMA

The main features of their cover are as follows:

  • Liability Coverage for the Operation of Model Aircraft, Boats, Cars, and Rockets
  • $2,500,000 Comprehensive General Liability Protection for model activities for members, clubs, site owners, and sponsors
  • $25,000 Accident/Medical Coverage for members
  • $10,000 Maximum Accidental Death Coverage for members
  • $1,000 Fire, Theft, and Vandalism Coverage for members
  • Primary Site Owner Insurance
  • Cost: Age 19-65 – $75, 65 & over – $65

AMA Liability Protection applies to bodily injury or property damage caused by an AMA member. Any AMA  member who causes an accident resulting in an injury must report that accident immediately to AMA HQ.  This applies to accidents arising from the modelling activities of model aircraft, rockets, cars and boats, in  accordance with the AMA NATIONAL Safety Code(s).

There is no coverage for injury to a member or to his own family (Household and Relative(s) living in the member’s household) for claims or suits.

The policy does NOT cover business pursuits, i.e. any activity that generates income for a member beyond reimbursement of expenses. This business pursuit exclusion does not apply to individual members providing modelling instructions for pay to AMA members.

There is a $250.00 deductible (property damage only), which is the responsibility of the AMA member causing the accident.

The Accident/Medical coverage applies to injuries while engaged in model activities regardless of who causes the accident. It reimburses an AMA member in accordance with policy terms and conditions for only medical expenses (also the beneficiary for loss of life) incurred within 52 weeks of the accident.

The Accident/Medical coverage works as follows: It provides up to $25,000 for medical expenses and $10,000 for dismemberment or death.  The AMA member is directly insured and does not require a claim action by another person.

It pays for eligible expenses upon submission of bills or other documents certifying cost of treatment and that injury was caused by model activity.

Medical expenses are reimbursed only after submission to any other health plan, including Medicare.

There is a $750.00 deductible in respect of Fire, Vandalism, and Theft Coverage.

It provides up to $1,000 for loss of aircraft models and accessories, including RC equipment.  All theft loss  claims must be accompanied by a police report. NOTE: Theft has to occur from a locked vehicle or residential dwelling and there must be physical evidence of violent forcible entry.

There is a $100.00 deductible “excess” to any other applicable coverage, such as homeowner’s insurance.

Park Pilot Insurance

Park Flyer models must weigh two pounds or less and be incapable of reaching speeds greater than 60 mph. They must be electric or rubber powered, or of any similar quiet means of propulsion. Models should be remotely controlled or flown with a control line, remain within the pilot’s line of sight at all times, and always be flown safely by the operator.

The “per occurrence” limit of coverage available by this policy is $500,000 for claims involving bodily injury and/or property damage. These limits are for claims occurring during the policy period.

Coverage is provided only for accidents arising from the model activities.  There is no coverage for injury to a member to his own family (Household and Relative(s) living in the member’s household) for claims or suits.

The policy does NOT cover business pursuits, i.e. any activity that generates income for a member beyond reimbursement of expenses. This business pursuit exclusion does not apply to individual members providing modelling instructions for pay to AMA members.

This AMA insurance has a $250.00 deductible for property damage only, which is the responsibility of the AMA member causing the accident. Is over and above any other applicable coverage such as homeowner’s insurance.

This information is merely a brief summary. Complete details of coverage and exceptions are contained in the master policy available at www.modelaircraft.org

Insurance Through The BMFA

  • Civil liability insurance and personal accident insurance.
  •  Up to £25,000,000 per claim.
  • A county member receives exactly the same insurance benefits as members who join through a club. 
  • BMFA Insurance provides worldwide cover.
  • Cost:  Seniors £33 per annum, Junior £17 per annum.

BMFA insurance cover commences from the moment you pay the BMFA element of a Club joining fee to your nominated Club official. You do not have to wait for receipt of your BMFA membership card.  The most important factor is that the club have collected the fee and have formally registered you as a paid up member of the Club.

A Country Member is one who applies directly to the BMFA for membership (although they may or may not join a club), either by telephone or online, or joins at the BMFA stand at a show.  Here the member is technically insured from the date the application is received and processed although they do not receive their membership card until a few days later (postal services permitting).

Clubs may offer temporary BMFA membership and insurance cover to visitors to the Club from within the UK, who are not BMFA members but have been invited to use their flying facilities on a temporary basis.  A non-refundable fee of £5 is payable for a single period of 30 days.

Clubs may also offer temporary BMFA membership inclusive of insurance cover to visitors from overseas countries provided they are not involved in display or competition flying.  In the interest of international relations no charge is  made for this class of membership which again may be offered for a single period of 30 days.

Club liability insurance can be extended to cover first time visitors to a Club who have no previous experience of model flying but are seeking to try out model flying prior to joining a Club.  In this case cover will only be in place when the flights are being personally supervised by a nominated Club member approved by the Club Committee.  No charge will be made for this additional cover which will only be in place for a maximum of 3 days for any one first time flyer.

To learn more about the BMFA membership services visit www.BMFA.org .

Why Risk It?

I know that there are many people around the world flying radio controlled model planes of all shapes and sizes WITHOUT insurance cover. Don’t become this sort of irresponsible flyer, get covered for yours and your dependents peace of mind and for the protection of others.

The mere thought of causing any kind of damage without the protection of model aircraft insurance puts me in dread and is a scenario I dare not envisage.

If you have found this post useful take a look at some of my other posts at www.rookiercflyer.com.

Colin

 

 

 

 

 

 

January 15

Differential on Ailerons for Radio Control Aeroplanes

Several posts ago I gave an in-depth explanation of Setting Up Servos For RC Planes. As a result of this I was asked by a couple of readers for an explanation of the need for differential on ailerons for radio control aeroplanes.

This is an interesting subject and quite an advanced subject that doesn’t normally concern those learning to fly rc planes. Most trainer type models do not suffer from this phenomenon because of the way they are designed. However, as the question has been asked I will bite the bullet and try to explain things in as simple a way as possible.

Adverse YawAdverse Yaw

You may ask why aileron differential is necessary and what it is. Let me handle the first question then we can go on to discussing how it can be achieved.

In the diagram on the right the view shows an aeroplane that has control inputs trying to cause a right hand turn. The left aileron has moved downward and the right aileron upward.

The theoretical result of this control input is to create greater lift under the left wing and a reduced lift under the right wing. As a consequence the plane should bank over to the right and there will be a tendency for it to start a turn to the right. This is then helped by the input of a small amount of up elevator to increase the overall lift generated by the wings.

Unfortunately, there is a complication associated with the change of lift under each wing. The down going aileron increases induced drag of the left wing to a greater extent than that of the right wing. Lift and drag are inexplicably linked – the more the lift, the greater the drag. You can see in the diagram the drag arrows at the wing tips are out of balance, that at the left wing being greater than at the right wing.

The initial effect of this imbalance in the increased drag is to try to rotate the plane to the left around its horizontal axis. This is what is meant by Adverse Yaw and is a problem that arises in many types of aircraft.correcting yaw using rudder

The usual way of counteracting it is by applying a rudder input in sympathy with the aileron control. In other words, initiating the turn by applying right rudder marginally before applying right aileron. The effect of this is to commence a rotation around the horizontal axis which reduces the lift of the right hand wing.

Once this occurs the application of the right aileron turn input becomes more effective and the desired right hand bank is achieved.

Why Aileron Differential?

I have just explained that Adverse Yaw can be counteracted by using rudder so why the need for Aileron differential?

Well, many people who fly rc model planes find co-ordinating rudder input and aileron input together somewhat difficult. So to make life easier it is possible to use aileron differential to accomplish the same result.

First of all what is aileron differential? Quite simply it means that the Aileron Differentialailerons are arranged so that they move more in one direction than the other. Usually this is more UP than DOWN.

I have already mentioned the fact that a DOWN going aileron generates more induced drag than an UP going aileron. It is the extra drag that causes the adverse yaw that we want to avoid.

If we arrange for the aileron that goes up to move more than the one that goes down, we reduce this additional induced drag whilst still achieving the bank angle we need to make a turn.

Arranging Aileron Differential

We can arrange this differential in at least three different ways.

  1. Raked Torque Rods
  2. Offset Servo Output Arm Position
  3. Via Transmitter Programme

We’ll take each of these in turn.

Raked Torque Rods

The torque rods we are talking about are those attached to the control servo linkagesurfaces and connected to the ‘servo arms’ by the ‘pushrod’. In the illustration here it is called the ‘control horn’.

You will find that on most planes the control horns are fixed to the underside of the control surfaces, unlike this illustration.

Here we see the normal correct arrangement where the clevis connecting holes are perpendicular to the hinge line. This guarantees equal movement either side of the neutral position. We need to change this so that, with the control horn below the surface, there is more movement upward than there is downward.

To achieve this the coupling of the clevis connection to the control horn needs to be forward of the hinge line. The further forward of the hinge line we set this point the greater the differential between up and down aileron movement.

Aileron Differential

Ok, I know this looks like a complicated drawing but let me try to explain it before you run away in despair. It’s not so difficult to understand.

First of all take the servo. As and Bs represent the linear movements either side of the neutral position when the transmitter aileron stick is moved to its maximum deflections both up and down. These are identical distances.

Now move right to the circle describing the arc of potential movement for the control arm or horn. The dark line at the bottom shows this attached to the underside of the control surface and extending down and forward to a position where it has a ‘forward offset’.

The two dotted lines linking the servo output arm to the control arm show the range of transferred movement to this horn at full deflections fore and aft.

Finally we see the range of movement of the trailing edge of the control surface as Ac and Bc. it is clear to see that the down movement (Ac) is considerably less than the up movement (Bc).

This has created a differential of movement that reduces DOWN aileron but increases UP aileron. As UP aileron does not induce so much drag as DOWN aileron we have balanced out the tendency of the drag to cause an adverse yaw about the horizontal axis to the left.

I hope that this has made some sense to you.

Offset Servo Output Arm Position

This is the alternative mechanical solution to our problem. Most servos currently available have a round toothed output shaft or spline to which the output arm is attached using a small self tapping screw positioned centrally.

This means that the output arm can be positioned on the toothed shaft in a wide array of positions. Normally this position is when the connection between the arm and the pushrod are at right angle to each other (90 degrees).

To achieve our differential movement at the aileron with more up than down,Servo Offset we need to position the servo output arm with a measure of forward bias.

In the diagram on the right we have positioned the servo output horn several degrees forward of the perpendicular line through the spline axis. The result is that the linear pushrod movement As will now be less than Bs.

As Bs is responsible for driving the control surface upwards, with the pushrod running left to right, you can see that the surface UP movement will be greater than the DOWN movement.

This has achieved for us exactly the same result as the Raked Torque Rod/Control Horn in the previous example.

Via Transmitter Programme

Most modern digital transmitters have programming facilities that enable the pilot to make adjustments to the magnitude of control movements in each direction independently.

This means that by going into the transmitter setup mode one can increase or decrease the upward or downward, left or right movement of each control surface. You will need to follow the radio gear manufacturers instructions to use this facility.

Summarising Differential on Ailerons

I hope that the above explanation has not proved too difficult for you to absorb. I know it is a fairly technical aspect of Radio Controlled model airplane flying but it is important to have an appreciation, first of all, why Adverse Yaw occurs and, secondly, how we can eradicate it.

If you are having difficulty understanding my explanation, I suggest you talk to your club tutor about differential for ailerons and how to set it up mechanically. In my opinion adjustments at the transmitter should be a last resort, not the first port of call for solving this kind of issue.

If you have enjoyed this post, be sure to visit my main site www.rookiercflyer.com to find loads more useful information for beginners.

Best of luck,

Colin

 

 

 

 

January 8

RC Airplane Model Making Tools, Equipment and Accessories.

As you develop your interest in flying rc model planes and progress to more advances subjects you will inevitably discover the need to acquire a larger collection of modelling tools to help you move forward.

In my main site www.rookiercflyer.com I covered the basic tools you would require to maintain your plane in flying condition. This post will cover a selection of rc airplane model making tools, equipment and accessories that will make your life easier especially if you decide to go on to building your planes from plans or construction kits.

TweezersTweezers

When trying to position screws in awkward situations a pair of tweezers can be an absolute godsend. They can also be mighty useful for retrieving small parts dropped into confined spaces.

Good spring steel ones will retain their shape and tension in use whereasHemostats cheap soft metal ones will bend and lose their ability to grip things.

The self closing ones on the left of the selection shown here are  often most useful.

The scissor like tools shown to the right will provide a stronger grip than standard tweezers and the extensions near the finger eyes lock together to keep pressure on whatever is being held.

A Long Sander

There will be many instances when you may need to sand flat a larger area of wood or to smooth off a number of pieces of wood spread across a distance, typically the edge of a wing or a set of wing ribs in situ.

The ideal tool for this is a long sander of the type shown here with selfLong bed sander adhesive sandpaper applied to its underside. Alternatively it can be a wooden one so long as the wood cannot flex under hand pressure in use.

The one shown here is a commercially available item provided with a dust extraction facility. The underside of the sanding plate is perforated and the outlet at the rear can be attached to a vacuum cleaner via a hose to take the wood dust away from the work area.

A long sander is best used two-handed (hence the handle and knob) to control the pressure evenly across the surface being sanded. Alternatively, if more pressure is needed at one end, this is more easily controlled using both hands. The tool should be held obliquely to the length of the sheet and used like a plane.

To shape ribs, move it from the highest point of the wing, usually at the main spar and work either toward the leading or trailing edge. Do not work across the ribs as they can easily be split. The two handed operation enables each end to be moved at different rates especially on wings that taper from root to tip.

Use light pressure only with a fine or medium grit paper, taking care not to create any flat spots.

Combination Square & Adjustable Bevel

The combination square can fulfil several functions besides beingCombination square a try-square. You can use it as a depth gauge and for measuring distances at 90 degrees and 45 degrees to an edge.

Be sure to buy a good quality set as cheaper ones can be suspect in measuring these angles accurately.

It  can be used to determine a distance by sliding the adjustable fitting along the rule until the projection matches the length. Then several components of identical length can be marked by laying them along the rule without having to read and transfer the measurement to each piece.

If you need to match a workpiece to a specific angle on a structure, The adjustableadjustable bevel bevel can be set to the exact angle within the structure between the blade and stock and then transferred to the workpiece. This ensures a perfect fit of the component into the measured angle.

To ensure accuracy it is important to ensure that the angle is measured with the face of the stock in the same plane as will be the face of the new component when it is fitted in place.

 

Soldering Tools40W soldering iron

It is not always necessary to carry out any soldering to complete a model but the need will arise sooner or later. I have shown here three different versions selected for their specific uses.

The first is a 40 Watt version. This is probably the most useful size for the majority of soldering tasks you will encounter. It is capable of soldering medium cored wire and cable and most lighter steel rod applications.

The second one is a 100 Watt iron. This is ideal for joining thicker wires to connectors and100W soldering Iron larger pieces of metal.

You will notice that the soldering bit is considerably heavier and flatter than the 40W version. This enables it to transfer its heat more rapidly to the pieces being soldered. You will often find that the bits on heavy duty irons are angled over.

If you need to work on electronic circuitry you will require the smaller 15 Watt iron shown here. This is ideal for use on fine wire and other precision work but will not be capable of providing15W Soldering Iron the heat necessary for heavier duty work.

In some instances where heavy gauge piano (music) wire is concerned a gas-powered blow torch will prove useful. This applies very high temperatures to a specific location quickly and produces a very clean solder joint.

Obviously this kind of heat should not be used in close proximity to wood and radio control gear.Soldering Tips

It is always a good idea to buy soldering irons with interchangeable bits. Over time the first bit will start to deteriorate and you may find it necessary to replace it. Replacement bits are much cheaper to buy than a complete new iron.

Besides this, you can buy a set of bits with different points designed for different tasks. These can be very useful.

Other accessories that will help make life easier for  you include:Soldering Stand

a) A soldering iron stand with integral cleaning sponge – this will help protect your work surface and other equipment, to say nothing of your skin, from unintentional contact with the hot tip and body. It also provides a readily available bit cleaning facility. Good soldering and heat transference relies on your iron bit being scrupulously clean.

b) A solder removal sucker – The cylinder spring loaded type shown here below is the best type to have. Solder is removed from the component(s) by applying heat from a soldering iron and, while the solder is in a molten state, applying the tip of the sucker to the wet solder and releasing the spring loaded plunger. the solder is sucked up into the cylinder from where itSolder Sucker can be emptied when it has cooled.

c) Earlier I listed a selection of tweezers. The ‘self-closing’ one of makes an ideal holding tool for wires as well as being a good heat sink to protect more delicate items.

The Third Hand

Finally, although listed it in my post on soldering wires back in October 2015,Third Hand I am reviewing another most useful tool for soldering tasks. This is what is known as a ‘Third Hand’ and is shown here on the right below.

The magnifying glass and twin crocodile clips provide a very secure mount for small components to be soldered together and for positioning wire ends together ready for application of the solder and iron.

The assembly is made up of an arrangement of arms, ball joints, wing nuts and crocodile clips that can be adjusted to ant angle and position required to hold your components in the correct position for soldering.

It can also act as a heat sink for drawing excess heat from the components and keep your hand well away from the hot iron.

Balsa StripperBalsa Stripper

Some ‘plan pack’ style kits are supplied without the necessary strip balsa wood to complete the model. in this case you will need to either purchase the required strip wood separately or purchase sheet balsa of the required thicknesses and strip it down yourself to the required widths.

This device is a most useful addition to your tool collection for such situations. It employs a standard craft tool blade as you can see from the picture. The depth of cut is fully adjustable using the knurled knob opposite the blade fixing.

The one shown here is the simplest and cheapest option. I have used a differentSLEC Balsa Stripper version for many years manufactured by a British company – S.L.E.C. This is pictured here on the right. It comes with a section of aluminium channel in which the cutter slides. This channel needs to be fixed firmly to a base board to complete the assembly. A selection of spacers are supplied to increase or decrease the depth of cut as required.

I can highly recommend this version. it has served me well over a good number of years.

A word of warning here: Because these strippers use craft blades there is a tendency for them to introduce a bevel when cutting thicker sheets due to flexing of the blade trying to follow the grain of the wood. this is particularly evident when cutting more dense, heavier balsa.

The way to eliminate this is to set the blade so that it cuts only halfway through the wood. Make the first cut and then turn the wood over and complete the cut from the other side.

Always be sure to hold the sheet of balsa firmly against the guide and cutting surface to prevent it moving away from the edge of the stripper.

I would not recommend stripping anything thicker than 1/4 inch (6mm) using this type of cutter. You may get away with 3/8 inch (9mm) using the double cut approach.

Strips should be cut from medium to hard balsa for most uses. Soft balsa becomes to weak when stripped down.

Allen (Hex) KeysAllen Keys

These are commonly used on Glow/Nitro engines both for securing components such a silencers and carburettors as well as for fixing the engine to its bearers.

They are also used to fix propeller adaptors to shafts on electric motors and for some types of control surface linkage fixings.

Generally speaking you will only need the smalle sizes so no need to buy a selection of the larger sizes.

Small SpannersSmall Spanners

A few small spanners make a very useful addition to your tool kit for tightening nuts, especially those that secure propellers on shafts and, in some cases, mounting engines.

The benefit of using a spanner to tighten nuts rather than using a pair of pliers is that the corners of the nuts or hex bolt heads do not get damaged.

On humorous note: It’s surprising how much damage can be caused to your nuts when they are gripped by a pair of pliers!

Vernier CalipersVernier Calipers

This tool provides a far more accurate method of measuring the diameter of drills, bolts and wire rods, etc. If, like me, you are not the most tidy of persons then occasionally you may need to sort out your small drill bits having forgotten to reposition them in their correct graded holder. The Vernier Caliper is the ideal tool to re-establish the exact size of the drill shafts.

The price of ones with digital readout displays has dropped dramatically recently so although not an everyday requirement, they represent a really useful acquisition.

Taps & DiesTap & Die Set

Generally these are only necessary if you intend to advance into the realms of model engineering. However, a 2BA or 5mm tap and tap wrench are useful for cutting a thread into a plywood wing bolt retainer in smaller models.

Rather than drilling out and fitting a blind nut for this bolt (usually Nylon), it is possible to drill a pilot hole in the plywood and then tap a thread into this hole. It helps to harden this thread buy soaking it in thin cyano glue then, one it has hardened, pass the tap through the thread again to smooth it out.

This type of fixing should not be used on larger, more powerful models. These need the security of blind nuts and larger bolts.

VicesMedium Size Bench Vice

A decent bench vice albeit a small one will prove most useful if you need to grip a piece of metal for cutting with a saw. Hack saws, both junior types and larger ones, are notorious for grabbing during a cutting stroke. If you are holding the metal, even in a gloved hand, considerable pain and damage can be caused.

It is also very useful for holding metal components that need to be heated above temperatures suitable for skin contact. The jaws act as a very good heat sink in such situations.Small vice

You will need a good solid bench for it to be attached to. Alternatively, a sturdy board will suffice, clamped to your work surface if you don’t want the vice to be a permanent fixture on your bench.

There are smaller vices available for lighter jobs such as the example here. these are easily moved around to suitable locations providing you have a level surface to clamp it to.

Pin Vices

Often when mounting such things as servos, pinned hinges, etc. The use of a power drill can be too aggressive and cause excessive damage to the soft woods you are fixing to.

Hand Pin VicesIn these instances an alternative method of piercing the wood is desirable and this is where a pin vice comes into its own.

Essentially, this tool is a miniature set of drill jaws designed to hold small drill bits with a handle for hand operation.

Because there is a limit to the amount of expansion and reduction of the jaw capacity, the range of bit sizes each one can accommodate is very limited.

Fortunately they are normally supplied in sets to accommodate a reasonable range of bit sizes as shown here.

I find these a most useful aid to many tasks in my workshop.

Wire BrushesMini Wire Brushes

A small set of brass and steel wire brushes are most useful for cleaning tarnished tools, complex shaped components for soldering and for removing the build up of metal bits that become stuck in the teeth of files.

Templates & French Curves

When marking out on wood and other materials it is useful to have a set of flexible drawing aids to assist with these tasks.

I find that plastic templates are very useful for this purpose particularly plastic templateswhen drawing circles and other curved lines.

They are also very useful for marking out panel lines and other surface features on scale models. E.g. Panel lines, access hatches, etc.

Chose reasonably flexible and transparent ones so that they are easy to position without hiding  markings and locating features beneath them.

French Curves are invaluable for transferring curves to materials to be cut. They are very helpful when joining pin pricks in balsa wood that have been made through a plan. To achieve the correct outline of the shape to be cut French Curvesplace the appropriate section of a curve against the pin pricks and join them together with a suitable pen.

To Summarise

This list is by no means comprehensive and I could go on adding useful tools to the inventory.

Many of these tools will never be used by some flyers, especially those who only purchase ARTF models.

Even those of you who decide to become serious modellers will not require all of them immediately. I have gathered together my personal collection of model making tools, equipment and other accessories over many years of real modelling.

I bet you’re wondering where the best source is to obtain the items discussed in this post. Well, I can highly recommend Amazon as a good source at very reasonable prices. If you feel you would like to acquire any of these items promptly then you can order on line by clicking either one of the links below:

Amazon.co.uk

or

Amazon.com

When the Amazon home page appears just enter into the search bar the name of the item you want and hit return. A selection will appear from which you can choose the one you wish to purchase and complete the transaction on-line.

Please feel free to contact me through the comment facility if you require any further help or advice on selecting tools for your use.

Don’t forget to visit my main site www.rookiercflyer.com if you have enjoyed this post and are in the early stages of learning to fly rc planes.

Good luck,

Colin

 

 

January 2

Understanding RC Electronics

Electronics_schematic_UBEC
Motor/ESC/Lipo circuit with UBEC receiver supply.

The growth in the number of electrically powered radio controlled model aircraft being purchased is quite amazing. Most newcomers to electric rc model flying have virtually no knowledge of electrics to back up their choice. This can lead to frustrations when things start to go wrong and components cause problems.

I believe that understanding rc electronics in its simplest form is important for your success in flying electric rc model planes. To this end I am going to  give you some basics to help you  along the road to your success.

Measuring Electricity

 We can measure electricity in a number of different ways, but there are certain units of measurement that are particularly important.

 VoltageVolt drop

The voltage is a kind of electrical force that makes electricity move through a wire and we measure it in volts. The bigger the voltage, the more current will tend to flow. So a 12-volt car battery will generally produce more current than a 1.5-volt flashlight battery.

Current

Voltage does not, itself, go anywhere: it’s quite wrong to talk about voltage “flowing through” things. What moves through the wire in a circuit is electrical current: a steady flow of electrons, measured in amperes (or amps).Current mearurement

Power

Together, voltage and current give you electrical power. The bigger the voltage and the bigger the current, the more electrical power you have. We measure electric power in units called watts.

The electric power in a circuit is equal to the voltage × the current (in other words: watts = volts × amps). So if you have a 100 watt (100 W) light and you know your electricity supply is rated as 120 volts (typical household voltage in the United States), the current flowing must be 100/120 = 0.8 amps.

If you’re in Europe, your household voltage is more likely 230 volts. So if you use the same 100-watt light, the current flowing is 100/230 = 0.4 amps.

The light burns just as brightly in both countries and uses the same amount of power in each case; in Europe it uses a higher voltage and lower current; in the States, a lower voltage and higher current.

Energy

Power is a measurement of how much energy you’re using each second. To find out the total amount of energy an electric appliance uses, you have to multiply the power it uses per second by the total number of seconds you use it for.

The result you get is measured in units of power × time, often converted into a standard unit called the kilowatt hour (kWh).

If you used an electric toaster rated at 1000 watts (1 kilowatt) for a whole hour, you’d use 1 kilowatt hour of energy; you’d use the same amount of energy burning a 2000 watt toaster for 0.5 hours or a 100-watt lamp for 10 hours. See how it works?

The Difference Between Electrics and Electronics

Now we need to differentiate between Electrics and Electronics.

Electronics is the technology of electrical circuits that are made up from active electrical components such as transistors, diodes and integrated circuits.

It is distinct from electrical technology which deals with the generation, distribution, switching and conversion of electrical energy into other forms (e.g. light and motion) using wires, motors, generators, batteries, switches, relays, transformers, resistors and other passive components.

Electronics is the knowledge of how individual components work and how to assemble them together to make a working device, while electrical technology is the knowledge of how to connect together different devices to turn electrical energy into useful stuff like heat, light and motion.

This means that anyone with a basic knowledge of ‘model electrics’ can install the necessary circuitry to make a model plane do what he (or she) wants it to do without actually understanding the clever workings of the electronic bits in the circuit.

Our radio control electrical circuit involves a power supply, conductive wiring, a load and a switch. The circuit is dead until either the switch is made or the power supply is connected directly to the circuit, at which stage a current of electricity flows through the wiring of the circuit and energises the load.

The load does whatever it does for as long as the power is supplied and can be anything that consumes electrical energy such as a receiver and servos or a receiver, servos, ESC and motor. When the switch is returned to its original position or the power supply is disconnected, the circuit becomes dead again and the load stops whatever it was doing.

What is a Circuit Schematic Diagram?

A circuit diagram, or a schematic diagram, is a technical drawing of how motor esc lipo receiver layout the various components of the system are connected together to achieve the end result.

Each electric component is drawn connected to the next by a line or lines representing the conductive wires that link the installation together as in the diagram on the right here.

Let’s now deal with the individual components of our circuit installation one at a time:

Battery

This is our power source and is essentially a store of electrical energy. It has two poles, or terminals, which are termed negative and positive.

The battery has chemicals inside it which react to produce little particles of electrical charge called ‘free electrons’ and drive them all toward the negative pole. This is insulated internally from the positive pole, which has a deficiency of electrons and whose sole function in life is to grab them from the other end of the battery.

If a metallic conductor, in the form of a thin metallic rod called a wire or a bundle of very thin rods called a cable, is connected between the two poles then the electrons will flow along it from negative to positive. This flow of electrons is called a current.

All batteries are identified by two very important properties. The voltage it holds puts a value on the electrical ‘pressure’ exerted between the negative and positive poles, i.e. the higher the voltage then the more electrical pressure it can exert on a load.

Increasing the voltage will, for example, makes a bulb glow brighter or a motor turn faster. The battery also has a ‘capacity’ which is a measure of how much electrical energy it holds and can supply before it becomes discharged, or ‘flat’.

The rate of flow of electrical current along the conductor is measured in Amps or, to give it its full name, Amperes.

The more amps a load draws from the battery then the quicker it will discharge.

The value of a battery’s capacity is the arithmetical product of the current and the amount of time for which it can be supplied and is quoted in Amp-Hours (AH), or Milliamp-Hours (mAH) which are 1000 times smaller.

A battery which can supply one amp for one hour has a capacity of one amp-hour. To give a figure more typical of an rc model plane application, a 3000mAh (3AH) battery will supply a current of 2 Amps for 1.5 hours (1.5 x 2 = 3).

I hope you will have noted that this does not depend upon the voltage of the battery. This is a different thing altogether.

There is an arithmetical relationship between voltage and current in a circuit Ohms Law triangleand it’s called Ohm’s Law and states that the voltage across a load divided by the current flowing through it is called its resistance and its formula is:

R=V ÷ I.

Also by re-arranging the formula in line with the triangle:

V = I x R  and  I = V ÷ R

R = Resistance, V = Voltage and I is the usual symbol for current. For most practical purposes you won’t need Ohm’s Law on a day to day basis but it’s useful to be aware that it exists, if only to know what ‘resistance’ means.

Batteries For RC Model Aircraft

Basically there are two types of battery in common use for rc airborne applications. These are Nickel Metal Hydride (NiMH) types and Lythium-Polymer (LiPo) types.

Nickel Metal-Hydride (NiMH) batteries are generally made up in packs of end-to-end joined-up cells. 4.8V NiMH batteryThis arrangement is called ‘series’ connected.

Each cell has a nominal voltage of 1.2 volts and the cells are available in different case sizes. The smaller case sizes have the smallest capacity; typically around 850mAH for an AAA pack, while the largest cells, ‘F’ size, go up to 10000 mAH (or 10AH). 

NiMH cells can be fast-charged at the field from a portable charger. When fully charged, a NiMH cell can have as much as 1.55 volts across the poles. This will quickly settle down to its ‘nominal voltage’ of around 1.2v and stay at that level until it is almost fully discharged where the voltage starts to drop quickly and should not be allowed to go below 1v per cell or damage will occur.

Lithium Polymer (LiPo) batteries are the latest technolgy and are lighter and more powerful even than NiMH cells. Their nominal voltage is 3.7v per cell, BUT they do have to be carefully handled and monitored. Careless handling or overcharging/discharging can in the extreme case, cause them to catch fire and even destroy your model. Lipo battery

They have become the main choice of power source for electric flight. Treated with care and respect, they deliver excellent power to weight ratio so long as their sensitivity to over-discharge problems is taken account of.

For this reason it’s always advisable to use a speed controller which will monitor the battery voltage and cut off the power to the motor before it reaches a critically low value.

That said, LiPo batteries are in use all over the world and instances of such accidents are becoming rare.

It is essential that you purchase the correct type of balancing charger and follow the instructions, then you will have no problems.

LiPo packs come in multiples of 3.7v and are quoted in the form ‘XS’ where X is the number of cells. Thus a ‘3S’ pack is 3 x 3.7 = 11.1 volts.

The capacity is quoted in mAHs, and the maximum current which can safely be delivered is given in the form ‘YC’, where Y is the value of the capacity in mAH/ 1000 = AH

As an example, a 1700 mAH LiPo pack has a corresponding ‘C’ value of 1.7 and so a pack rated at 20C can supply a maximum of 20 x 1.7 Amps = 34 Amps.

Polarity

Previously I described how there is a flow of electric current when a load is connected between the two poles of a battery. Unfortunately some loads are sensitive to which way around they are connected (polarised) while others aren’t.

Examples of non-polarised loads are conventional bulbs, relays, switch terminals and fuses.

Practically any unit which includes semiconductors (transistors, Integrated circuits, etc.) will be polarised, so make sure that you connect items such as speed controllers and receivers the right way around. They are usually marked with + (positive) and – (negative) signs/labels or at least the instructions will tell you how to connect them.

Be warned, if you connect up a polarity-sensitive device the wrong way round, even for a split second, then you will probably damage it and often fatally.

Conductors

All wiring used to connect the various components of our rc and power system are forms of conductor and usually of the insulated flexible variety. This enables complicated circuits to be accommodated inside our fuselages and wings with lots of formers, ribs and electronic gizmos to be negotiated.

A wire, or cable, is made up of a central conductive core, usually multiple strands of thin copper wire, and an insulating outer sleeve.

The sleeve is typically either PVC in the case of the rc linkages or a silicone-based compound, which is more flexible and resistant to heat for the motor power circuitry.

The most crucial factor as far as wiring is concerned is to use the right thickness/diameter. Too high a current passing through a thin cable will increase its temperature to the point where the insulation breaks down and melts and the conductor inside can short out against other ‘live’ components.

Circuits in rc planes are typically of two types; those which provide power to motors and those which don’t. The former will be subject to high currents while the latter will only carry a few amps at most.

The accepted standard is to use thick multi-strand silicone-coated cable for power wiring, and thinner multi-strand PVC ‘hook-up’ wire for such items as receivers and servos. Most products bought ‘over the counter’ will come fitted with the appropriate gauge and type of wire and often with the appropriate connector attached.

The gauge of the silicone covered wire is usually quoted in AWG (American Wire Gauge) and the following table will be useful when working out what gauge of wire you need:

 

AWG               Conductor dia.(mm)          Max current (Amps)

10                                2.59                                        55

12                                2.05                                        41

14                                1.63                                        32

16                                1.29                                        22

18                                1.02                                        16

20                                0.81                                        11

22                                0.66                                        7

 

Switches

I know it may seem obvious but as we are discussing all of the major components in the system, we should also include these items.

Switches are devices usually operated manually and used to turn electrical circuits on and off. Slide Switch

In its simplest form, a switch has a lever which moves a conducting piece of metal into a position where it makes contact with another fixed conductor, thus bridging the two and allowing an electrical current to flow between them.

Each of these conductors is called a terminal (or pole) and is connected to the wires within the circuit, thus controlling the current in that circuit,

slide switches are usually fitted by radio manufacturers in the wiring harnesses that they supply to connect receivers to battery packs.

 

Series versus Parallel Connection and Loads

At this point I will have to explain those confusing terms parallel and series. There are two very simple rules here.

Loads connected ‘in parallel’ go alongside each other in side-by-sideParallel Resistors (parallel) cables which are then connected at each end (see diagram right). The voltage across each load will equal the total voltage across the circuit, Figure 6.

Loads connected ‘in series’ are connected one after the other along the same cable. The voltages across each load will add up to the total voltage across the circuit.Series Resistors

The terms ‘series’ and ‘parallel’ are also applied to connecting batteries, but beware! While you can connect two batteries with different voltages and capacities in series, you must NEVER connect two batteries of a different voltage in parallel or one will discharge into the other, with potentially serious damage to both batteries and possibly the model.

The total voltage of a series pair of batteries will be the total of the two battery voltages and the capacity will be that of the individual batteries.

The voltage of a parallel pair will be the same as the two individual batteries and the capacity of a parallel pair will be twice that of the individual batteries.

Be sure to always make sure that the two batteries in the pair are the same type (e.g. NiMH or LiPo) and the same capacity (e.g. 3000mAh), irrespective of whether you are wiring them in series or parallel.

If you are using two battery packs of the same voltage and capacity to power a plane, you should disconnect pairs of batteries from each other when charging. Charge them separately as there’s always the risk that one will charge at a different rate and that one will become the weaker of the two if you charge them together as a pair.

Brushless motors

Over recent years there has been a major revolution in model motor technology with the advent of brushless motors. As the name suggests, these don’t rely on fixed brushes to transmit the power to the central armature. Rather they are made ‘inside out’ with the wire coils fixed around the inside of the motor casing and a permanent magnet rotating the shaft inside them.

The power to energise the coils is transmitted by some very clever, fast-switching electronics outside the motor case. Because there are no brushes, these motors are much more efficient than their brushed cousins, so a small and light brushless motor will do the same job as a bigger, heavier brushed one.

To learn more about brushless motors visit my main website page on Electric Motors  where everything to do with these motors is explained in detail.

Electronic Speed controllers

There are two distinct parts to the inside of an ESC; the logic circuitry and the power circuitry.ESC

The logic components are the ones which are connected to the receiver via the 3-wire lead with a plug on the end. Its operating voltage is dictated by the receiver and is generally of the order of 4.8v.

The purpose of the logic circuitry is to detect and decode the signal coming from the receiver and to switch the high-speed, high-current semiconductors in the power circuit which control the speed and direction of the motor.

The ESC manufacturer will state in the technical information the range of main motor battery voltages that the ESC is designed to handle. They should also state a value for the maximum motor current (in Amps) which the ESC will handle under continuous operation.

You should be guided by those two values when choosing your ESC, after first ascertaining the working voltage of the motor and its current consumption under load as described earlier.

I’ve emphasised the words ‘under continuous operation’, because the current rating often causes confusion . When you switch on an ESC and bang open the throttle there will be a sudden inrush of current from the battery to the motor to get it spinning. This will always be a larger value than that consumed when the motor is running at full speed, i.e. continuously.

Modern switching semiconductors therefore have two current rating values; one for continuous and one for ‘inrush’ or pulsed currents. The value we should be concerned with is the continuous current rating.

My rule of thumb is to allow a 30% margin over and above the motor manufacturers recommended maximum continuous current rating. E.g. If the maximum recommended current for a particular motor is stated as 30Amps I would select an ESC that has a continuous current rating of at least 40Amps.

Always buy a known unit from a reliable source with a good reputation and a clearly stated service/warranty policy.  Incidentally it’s quite okay to run a low-current motor on an ESC which has a much higher rating, but not the other way around.

The power circuit connections of an ESC will always comprise a pair of thick battery cables. These are usually made in red and black, for positive and negative connections respectively. Always ensure they are correctly connected (+ to + and – to -)

Brushless motor ESC’s have three motor wires. It doesn’t matter which way round you connect the motor wires to the motor unlike the battery connections which should NEVER be reversed.

If you wish to reverse the direction in which the motor is rotating then just swap over any two of the three wires from the ESC to the motor.

Most standard ESCs for brushless motors will have been set by the manufacturer to a pre-determined operating mode and, when you switch on, will ‘Auto-set’ themselves.

If changes to operating modes need to be made, these can be done from your transmitter following the instructions supplied with the ESC or you may require a separate programming card to make changes to their working parameters.

Many ESCs contains a battery eliminator circuit (BEC) If it does, then you must NOT connect an additional power supply to the receiver.

To learn more about ESCs and BECs go to my main website page about ESCs & BEC circuits.

In Summary

In  this post we have covered just about everything you need to know about the control and power system of your electric rc airplane. If you familiarise yourself with the content you will have the basis of understanding rc electronics. There should be very little else you will require other than the information provided by the product manufacturers.

If you have found this post helpful why not visit my main website www.rookiercflyer.com for all the help you need to become a competent flyer. Any comments will be appreciated or I will be happy to answer any questions you want to ask via the comment facility below.

Happy New year everyone.

Colin