14.1 Almost Ready to Fly Models
(a) ARTFs are very popular and usually offer very good value for money but you should be aware that some airframes you may buy could have manufacturing or design defects. Close scrutiny of even a pre-covered airframe may pay big dividends if you can prevent a future failure.
(b) All visible glue joints within the fuselage should be checked, especially the engine bulkhead, fuselage bulkheads, wing mounting plates or wing dowels, undercarriage mountings and servo mountings. If you have any concerns then the reinforcement of many of these joints using scrap balsa stripwood will significantly increase the strength and durability of the airframe for very little weight increase.
(c) Take particular care when gluing wing panels together. Follow the manufacturers instructions and when adding such things as dihedral braces make sure that the whole joint is wetted out by the glue.
(d) Check pre-fitted pushrods, snakes and clevises for suitability. Most will be fine but some have been seen that were inadequate for the job expected of them, either being to thin or too weak. The rule of thumb should be ‘if I was fitting this, would I fit this’.
(e) Always check flying surfaces for warps – don’t assume that a wing will be straight because it was built for you. Minor warps can sometimes be removed by gently heating the covering, twisting the surface in opposition to the warp and holding until cool. Major warps are a reason for returning to where you bought the model.
(f) The ONLY acceptable (and beneficial) warp on an R/C model is matched wash-out. That is, looking from the rear the trailing edge at each wingtip is twisted upwards a little compared to the root of the wing. If this is present then it MUST be even on both wings or it’s just another warp.
(g) On i/c powered models, have a good look at the fuel proofing around the engine and fuel tank bay. If you are looking towards something more than a throw away airframe then an extra coat of fuel proofer in and around the nose will certainly be worth while.
(h) Extra care should be taken with second hand airframes as you will usually have no idea of their history. Close scrutiny of the whole airframe and any necessary repairs and strengthening are essential before you fly the model.
14.2 Ultralight R/C Models
(a) There are numerous electric powered ‘Slow Fly’ or ‘Park Fly’ models on the market that may be classed as ‘Ultralight’ and this is encouraging the flying of R/C models in places that have never seen model flying or which have been out of bounds to flying for many years.
(b) Although virtually all of these models are lightly loaded, great care must be taken when flying them as you can be led into situations that you would not face on a club field.
(c) Read the Safety Codes contained in this handbook carefully as virtually all of them still apply to this type of flying, especially those concerned directly with radio control.
(d) Be very careful to avoid flying near to existing model flying sites if you are using 35 MHz equipment. Find out where models are being flown in your area and check on a local map that your chosen flying area is far enough away to be safe.
(e) Take special care to avoid putting members of the public at risk. Your activities, with quiet slow models will almost certainly draw the attention of passers by - they could appear from anywhere.
(f) Park flyers have the possibility of introducing model flying to great numbers of the general public who may never have seen our sport close up before. Your behaviour and safety awareness could result in there being many new model flyers in the future.
(g) Be aware that some Local Authorities have by-laws banning the flying of powered models from their open spaces. Check carefully to avoid trouble.
(h) You may, however, find yourself in a situation where you are flying sensibly, safely and not causing a nuisance and are approached by someone who says he represents the Local Authority or some other official body and who tells you that you are not allowed to fly. You are within your legal rights to ask to see a copy of the by-law that bans flying on the area you are using.
If you still have trouble and you consider that your rights as an individual and a model flyer are being overridden, you should contact the BMFA office for help and advice as soon as possible.
(a) It cannot be stressed enough that a model helicopter must have a higher degree of safety built into it than perhaps any other flying model. Because the BMFA feels so strongly about this the following comprehensive guide is set out below. This is in addition to the regular R/C safety code.
It is VITAL that you never fly or run up your helicopter in or near the pits area or near spectators.
Rotor blades must always be carefully balanced. NOTE: modern premium quality carbon fibre rotor blades come pre-balanced. You should always remember that vibration in helicopters can be very destructive.
(b) Electric Model Setup
An electric model can start up with full power and torque immediately. The quickest / easiest method of making the model safe would be to disconnect at least two of the three motor wires which connect to the ESC. An alternative would be to remove the motor pinion / drive gear or belt so that there is no drive through the transmission or move the motor away from the drive gear. For some cases ie when adjusting the throttle end points on the ESC, the motor needs to be plugged in. In this instance ensure that you remove both the main and tail rotor blades. Be careful of loose clothing getting tangled in any rotating parts.
(c) For I/C Powered Helicopters
When starting the model in the pits, hold the rotor head firmly. When the engine is running carry the model a sensible distance from other people before running up or flying. Do not release the rotor of the model until you are sure that it is safe to do so and NEVER FORGET the amount of energy there is in a spinning rotor.
Never hold the model overhead to run up the engine or run the engine with no rotor blades fitted.
(d) For Electric Powered Helicopters
Electric helicopters should be carried out from the pits area with the flight battery disconnected and it should only be connected in a safe area away from people and not under the flightpath of other pilots. The model MUST be considered to be live as soon as this is done and great care is needed during this procedure.
(e) A MODEL HELICOPTER MUST NEVER, UNDER ANY CIRCUMSTANCES, BE FLOWN OR RUN UP:
(i) IN OR NEAR the pits area or close to any spectators.
(ii) Directly towards the pits area or any spectators.
(iii) With knife sharp leading edges on main or tail rotors.
(iv) With damaged or out of balance rotor blades. Note that blades, especially wooden ones, should be reinforced at the root with hardwood, glass-fibre or some other suitable material.
(vi) With radio equipment unproofed against shock and vibration.
(vi) In the presence of spectators or at a competition or fly-in until properly tested and proved airworthy.
(vii) Until thorough maintenance checks are carried out as set out in (f) and (g) below.
(viii) Note that all helicopters must be operated within the terms of our Article 16 Authorisation. Permission must be obtained to operate within an FRZ and those weighing more than 7.5 kg with fuel are limited to a maximum height of 400ft unless authorised by the BMFA.
(f) Checks Before Daily Flying Session
(i) With carbon fibre blades: check blades by twisting opposite ways at each end to ensure there is no delamination. Look down the blades to make sure there are no deformations. Check the root of the blades and leading edge to make sure there is no damage or chips. With wooden blades the same checks apply but pay particular attention to make sure the lead is glued in securely, the root of the blade has sufficient reinforcement, and the covering is in good condition, shrunk tightly and has no loose edges. As wooden blades are generally hand-assembled, be sure that they are balanced both statically and dynamically before use.
(ii) Pull main blade grips in and out to ensure there is no play.
(iii) Lift the head up and down to ensure there is no main shaft up and down play.
(iv) Check blade grip arms in case they are loose. Tighten if necessary with loctite.
(v) Check all ball links from top of the head to servos for excessive play. Change as necessary.
(vi) Make sure there are no missing bolts or screws in the servos.
(vii) Gently rotate the servo arms to make sure there are no notches in the gears.
(viii) Make sure there is no slop in the ball links on the tail push rod.
(ix) If there are any ball links anywhere else, check for excessive play and change as necessary
(x) Check that the boom and boom supports (if applicable) check they are securely fixed.
(xi) Check the tail blades as per the main blades.
(xii) Holding the tail blade grip, pull in and out to make sure there is no play.
(xiii) Check the tail fin is mounted properly and look over the whole tail to make sure all bolts are in place.
(xiv) If your helicopter has tail gears: check all of them to make sure all the teeth are there and there is no substantial wear/damage. Make sure the drive shaft is engaged properly and there is no excessive back lash. Adjust or replace as necessary.
(xv) If your helicopter has a tail belt drive: check all the teeth are in good condition and make sure the belt is tensioned correctly and all pulley screws are tight.
Checking motor primary drive (electric or i.c.)…
(xvi) With primary drive gears make sure that the back lash between the gear and motor pinion is adjusted correctly (if adjustable).
(xvii) If your helicopter has a belt primary drive, make sure the teeth of the belt are in good condition and that the belt is tensioned correctly. For electric helicopters, rotate the motor to make sure the bearings are in good condition and not rough and make sure that the motor is mounted correctly. Make sure the wires from the motor going to the ESC are plugged in correctly and aren’t rubbing anywhere.
(xvii) On your ESC (Electric Speed Controller) make sure that it is mounted securely, check the wires for any damage and the battery connectors for any corrosion / burn marks and replace as necessary.
(xviii) Extra checks for i.c. engine. Make sure the clutch rotates freely when rotating the main gear (without engine running). Ensure the motor is mounted firmly and correctly. Make sure the silencer is not loose and is mounted correctly. Ensure all fuel tubing is in good condition and change as necessary. (Fuel tubing becomes loose on its connections and can deteriorate and break up as it ages). Pay particular attention to the clunk fuel tubing inside the tank. Check fuel tank is in good condition and is not leaking.
(xix) Check all the wiring as a whole. make sure it is all plugged in properly and that none of the wires are rubbing anywhere.
(xx) Check the gyro / flybarless unit is mounted correctly and securely and where appropriate, make sure the aerials are in the correct position and have not sustained any damage.
(xxi) Check that the undercarriage is securely fixed and have a general inspection over the whole airframe for any loose fittings or bolts. Tighten and loctite as necessary.
(xxii) Carry out a range check if any changes or re-installation of equipment have taken place since the last session or if a history of range problems exists..
(xxiii) Perform a failsafe check.
How to check your failsafe is set correctly on an electric helicopter:
Prior to the failsafe test, make sure your transmitter is set to shut the motor off when the radio signal is lost as per your transmitter’s instructions. Remove rotor blades, both main & tail or alternatively disengage the motor drive to the main gear. Initiate spool up of the motor making sure you are not too close or have any loose items of clothing that can get caught up in the mechanics. Switch off your transmitter and motor will now shut down if the failsafe is set correctly.
How to check your failsafe is set correctly on an i.c. helicopter:
Checking failsafe on an i.c. helicopter is much easier as you do not need to remove the rotor blades and can check the failsafe without the motor running. Prior to the failsafe test, make sure your transmitter is set to shut the motor off when the radio signal is lost as per your transmitter’s instructions. Take a note of the idle position of the throttle on the engine. Put your transmitter to full throttle, switch off the transmitter and make sure the throttle returns to minimum idle or engine off position. Remember: THIS IS DONE WITHOUT THE ENGINE RUNNING.
(g) Checks Before Each Flight
(i) If a helicopter suffers damage or a heavy landing, recheck all of (f) above.
(ii) Check all controls before starting especially for binding of links or slowing of servos.
(iii) Re-check controls are performing as expected prior to lift off.
(iv) Check for vibration and eliminate before flight.
(v) Check main rotor blades for true tracking in hovering flight.
(vi) Check that the receiver aerial cannot become entangled with any moving or rotating part.
(vii) Double check that all switches are in their correct positions before EVERY flight.
(viii) Check that the gyro systems are responding in the correct direction (tail rotor and swashplate for flybarless models).
(ix) Check receiver and transmitter batteries have sufficient capacity for the flight plus a safety margin.
(x) i.c. model – make sure you have refuelled the model before flight.
For more information on the Association of Helicopter Aerosports, contact the BMFA's Leicester office.
(h) Helicopter Rotor Blade Safety
Wooden rotor blades- although they are not as common as they used to be, are still in use particularly for scale applications.
Rotor blade failures have five basic causes:
(i) Most design and manufacturing faults seen are centred around the rotor fixing hole. Typical faults are the hole being drilled on the junction between two wood laminations and incorrect wood selection leading to the hole being drilled in a soft lamination.
Blades with this type of fault should not be used. Even root reinforcement may not stop a failure.
(ii) Incorrect user assembly is commonly found in root reinforcements and in blades which have to have tip weight of some description added. In all cases you should take the greatest care that any components added are fitted correctly and with suitable adhesive. Incorrect glue joints and badly applied reinforcing components are probably the biggest single cause of blade failure so it is very important that you take the greatest care with any assembly work you have to carry out.
(iii) Do not be tempted to undertake any repairs to damaged rotor blades.
(iv) Any ground strike or boom strike will almost certainly cause damage to rotor blades and in many cases this may go unnoticed under the blade covering. If in doubt, have no hesitation in stripping off the covering for inspection. Re-covering and re-balancing the blades is a small price to pay for peace of mind.
(v) Ageing of glue joints in wooden structures is common and the high stresses inherent in rotor blade operation mean that you should keep a close eye open for delamination in wooden blades. A problem sometimes seen in composite blades is heat damage. Blades left in a car on a hot day can suffer from softening of the resin and this, combined with an expansion of the foam filler, can make the blades unsafe. To summarise, keep a close eye on your rotor blades and do not hesitate to discard them if you are at all concerned over their condition.
(i) Composite Rotor Blades
Modern production carbon / Kevlar / fibre glass blades are generally manufactured to a high standard and come pre-balanced as a matched pair or set; it is therefore possible to use them straight from the box. Caution should be exercised on pairing blades which have not been made as a set / pair ie two crashed pairs with one good blade from each pair. It is possible to do this provided the blades are of the same type / size & are balanced statically and dynamically.
Checks to make on Composite blades: check blades by twisting opposite ways at each end to ensure there is no delamination. Look down the blades to make sure there are no deformations. Check the root of the blades and leading edge to make sure there is no damage or chips.
(j) Metal Rotor Blades
The BMFA has agreed with the CAA that the use of good quality hollow extrusion metal rotor blades may be permitted on non-aerobatic models over 7.5Kg. Blades must be monitored for condition and withdrawn from use should there be any damage which would compromise their structural integrity.
Advances in modern electronics has lead to the development of a wide variety of multi-rotor aircraft of various shapes and sizes, with varying levels of autonomous abilities. However, it must be stressed that a pilot should not simply rely entirely on electronic autonomy alone for flight. If using autonomous modes, the pilot MUST be able to take back manual control of the aircraft at any time. It is VITAL that the pilot of any multi-rotor is aware of the abilities of their aircraft and knows what flight functions are available, how they affect the aircraft and how to operate them. The pilot MUST also be able to identify what mode the aircraft is in at any given time. This may be done by a visual indicator on the aircraft such as a beacon LED or via the transmitter switch positions or screen. Please remember that multi-rotors may not be flown in excess of 400ft above ground level at the launch point.
(a) Electric multirotors should be carried out from the pits area with the flight battery disconnected and it should only be connected in a safe area. The model MUST be considered to be live as soon as the battery is connected. As the position of multiple propellers is generally facing straight up at the pilot during arming, great care is needed during this procedure. It is worth remembering that electric models have the potential to go to full power the moment they are armed.
(b) Propeller orientation and motor direction is VITAL for multirotors and special care should be taken to ensure that everything is correct prior to attempting any flight. While adjusting the settings on a multirotor or during programming, propellers MUST be removed to prevent any accidental losses of control.
(c) Unlike fixed wing aircraft or helicopters that can glide or auto rotate after a power failure, a multi-rotor that loses a propeller, or suffers motor or esc failure in flight can become dramatically unstable with a total loss of control. Aircraft with six or more propellers may have an increased level of redundancy against total loss failures.
(d) Compared to most other model aircraft, where the electronics are enclosed within an airframe, multi-rotors tend to have exposed components. Therefore care should be taken to ensure they are kept free of debris and that all wiring is securely routed and not in a position to be damaged by or entangled with any moving parts.
(e) Multi-rotors require 3-axis gyros for stabilisation to enable flight and these are sensitive to vibration, so care should be taken to ensure all propellers are balanced and that correct anti-vibration materials are used where necessary.
(f) If you are intending to use your multi-rotor for FPV flying, then the relevant section of this guidebook MUST also be given careful review. Importantly, attention should be paid to the frequency that the pilot intends to use for their FPV equipment. The pilot must comply with any local video frequency control system, where applicable. In addition they should understand that switching their FPV equipment on while other pilots are flying FPV could result in a pilot losing video signal, so they should check that the frequency/channel they intend to use is clear before switching on.
(g) If you are intending to use your multi-rotor to carry a camera, then it is VITAL to understand the additional CAA regulations from article 95 (formerly article 167) of the Air Navigation Order.
(h) Many modern cameras have wireless connection options such as WIFI or Bluetooth, this may need to be switched off to avoid potential interference with the radio control signal.
(i) If using GPS on a multi-rotor it is VITAL that the system be given time to accurately locate the aircraft’s position before attempting to fly, taking off before a full GPS lock is achieved may result in an uncontrolled fly away. Where appropriate, a pilot MUST also understand when and how to calibrate the aircraft’s compass in line with the manufacturer’s guidelines in order to ensure accurate control of the aircraft is maintained.
(j) Intelligent Failsafes – In order to use intelligent fail safe modes, the aircraft will need, as a minimum, to be fitted with a control board capable of self levelling, with the more advanced options also requiring GPS to be fitted. If the aircraft is not capable of intelligent fail-safe, then the fail-safe mode should be set to reduce throttle idle/off as a minimum.
(i) Loiter – In this mode the aircraft will attempt to stay in a fixed position and maintain altitude upon loss of radio signal. It is intended that the pilot will then have the chance to get closer to the aircraft to in order to regain control. It is not advisable to use this mode without GPS, as the aircraft can drift away with the wind.
(ii) Controlled descent – Aircraft that can self-level may have the option to set the throttle to a soft point, such as to induce a smooth controlled descent on loss of signal.
(iii) Return to home – Aircraft capable of storing a take off point while using GPS may be set to return to their take off point and land autonomously upon loss of signal. It is important to note that in this mode the aircraft will typically fly a straight line from its current location to the take off point, so careful consideration should be given when flying near obstacles such as trees or buildings, which potentially may obstruct the return path. It is often possible to set the aircraft to climb to a ‘safe’ height, before returning. If ‘return to home’ is to be used, careful consideration should also be given to the location for the take off point, as the GPS modules may only be as accurate as 5 -10m from the original take off point.
(k) Checks before daily flying session:
(i) Check the propellers for damage and correct orientation, as well as ensuring that they are securely fixed to the motors or blade grips. This check should also include a careful examination of the propeller for any signs of stress, which is typically indicated by a ‘whitening’ of the plastic. This often occurs close to the hub and propellers showing any such damage should be discarded.
(ii) Check for loose or missing nuts and bolts
(iii) Check the motors for any signs of damage or debris
(iv) Check the airframe for any damage and ensure all components are secure.
(v) Check that the rotor arms are secure, especially in the case of collapsible/folding airframes.
(vi) Check all wiring is secure and routed safely to avoid snagging on any moving components.
(vii) Check that any gyro or flight controller is secure and that all aerials (including GPS) are secure and orientated correctly.
(viii) Check that the battery is secure and capable of supplying enough power for the duration of any autonomous flight stages planned.
(ix) Check that all aerials are securely attached, free from any damage or chafing and are orientated correctly.
(x) Ensure all transmitter switches are in the correct position for flight prior to initial arming.
(xi) Confirm the integrity/reliability of any FPV link, if appropriate.
(xii) If appropriate, check there is no backlash in the drive system apart from gear backlash, which should not be excessive.
(l) Checks before and after each flight.
(i) If the multi-rotor suffers damage or a heavy landing, recheck all of (k) above.
(ii) Check all controls before starting especially for binding of links or slowing of servos.
(iii) Check for vibration and eliminate before flight.
(iv) Check that all wiring is secure and cannot become entangled with any moving or rotating part, especially the receiver aerial.
(v) Before starting insure all switches are in the correct position for takeoff and the correct flight mode selected before EVERY flight.
(vi) If planning to use GPS at any point during the flight, confirm that you have a suitable lock before taking off. (Method for this will vary from unit to unit, but is typically by way of a flashing indication LED)
(vii) Check receiver and transmitter batteries have sufficient capacity for the flight plus a safety margin before the flight.
(m) Flight Modes
(i) Manual – The simplest of modes, the aircraft is still stabilised by the gyros, but only to enable flight. The aircraft will not self-level or fly autonomously in any way and can be rolled inverted.
(ii) Self levelling – More a feature than a full mode and can be used in conjunction with manual mode. The aircraft may still be manually inverted by rolling for example, however releasing the sticks will result in the aircraft automatically returning to an upright level position.
(iii) Atti – Sometimes referred to as ‘stabilised’. In this mode the aircraft cannot be rolled inverted, instead a full push and hold of the aileron or elevator stick will only result in the craft tilting to a set angle of approximately 30 degrees. Releasing the sticks to centre will see the aircraft self level to horizontal, however it will drift with the wind. This is often mistaken for manual mode, which it is not.
(iv) GPS – Sometimes called ‘position hold’. In this mode a GPS module is connected to the main controller and allows for additional autonomous aircraft control functions, such as ‘way point programming’ or ‘return to home’. Typically an aircraft flying in GPS mode will behave the same as one in ‘Atti mode’, however when the sticks are released the aircraft will no longer drift with the wind, but attempt to stay in one location.
(v) Geo-Fencing – Appearing in more and more controllers, geo-fencing is designed to prevent an aircraft flying in restricted areas, such as near a major airport. Pilots may find their aircraft either won’t take off at all, or will stop in the air as if it has reached an invisible wall.
(vi) IOC – ‘Intelligent orientation control’ (IOC) has a few different modes, such as ‘point of interest’ or ‘compass heading’. In these modes the basic controls of the aircraft can be changed at the flick of a switch to accomplish specific tasks, such as flying a perfect circle around a fixed point. A pilot should fully understand the different modes available via their chosen control board, how each mode will effect the controls of their craft and how to deactivate them quickly in case of an emergency. On some aircraft these modes cannot be used if the aircraft is within a set distance of the take off location.
(vii) Hazard avoidance – Some aircraft are now being fitted with sensors to prevent the aircraft flying in to obstacles, however these must never be relied upon in place of the pilot’s judgement.
14.5 Silent Flight – General
R/C silent flight models generally operate with low wing loading and low drag. Consequently, landing approaches may cover a lot of ground at low level. Check your landing approach path before you launch. Check again before you enter the landing circuit. Remember that people will not hear your model coming so take no chances.
When strong thermal or slope lift is encountered, beware of flying too high. At altitude, lift is often very strong and turbulent. Models fitted with spoilers or ‘crow’ brakes should have little trouble leaving such lift but do not try to dive out of strong lift if these are not fitted. Fly away from the lift and try to find sinking air. In an emergency, full up elevator and full rudder may give the safest descent.
Design considerations mean that many silent flight models are built light. Be sure that the design, construction and materials are adequate for the job.
Silent flight models are often flown at considerable distances from their pilots, therefore make sure that the failsafe is working properly before each session and a high visibility colour scheme can be a great safety factor. Be extra careful when flying at distance and/or height and beware of flying across the sun.
Remember also that both thermal and slope soaring flights can last for exceptionally long times. It is imperative that you ensure that both your receiver and transmitter batteries have sufficient capacity for the flight plus a safety margin.
14.6 Thermal Soaring
(a) When using a towline, bungee or power winch, locate yourself and your equipment well away from car parking areas and ensure that there is no possibility of launching lines falling on buildings, persons, roads or where they might distress wild, domestic or farm animals. Stay well clear of overhead power lines.
(b) Launch stresses can be severe. Be sure that wing joiners/attachments are strong enough to cope with the high loads imposed. The use of a ‘weak link’ of known breaking strain in launch lines is a measure that may safeguard model wing structures and should be considered.
(c) Bungee (Hi-Start) anchorages must be very secure. Use a screw-in type of fixing and do NOT peg the end down with devices such as old screwdrivers. Consider using guy lines on the stake for extra security and always do so if the stake is in soft earth.
(d) Electric winches should have an obvious, clearly marked master on/off switch accessible to anyone in an emergency. Shrouded plugs and sockets should always be used and the motor switching should be indirect, i.e. by relay.
(e) Turn-round pulleys must be very securely staked and braced with guy lines. Remember that the load at the pulley is double that on the line and pulley carrier geometry may produce even more load at the stakes.
(f) Whether you use winch, bungee or hand tow, make sure that spectators cannot be endangered if the model veers to one side on launch.
(g) Soaring pilots may tend not to stand together when flying. If this happens on your site then avoid overflying other transmitters at any distance from your own. It is your model that will suffer from interference and it could easily be damaged.
(h) Aerotowing requires careful handling of both the tug and the glider. Remember that to fly any model over 7 kg above 400 feet requires a permission. Your local club may already have such a permission as they may have taken advantage of the CAA scheme which allows site permission to be granted, but check before you fly. In controlled airspace contact the appropriate Air Traffic Control Organisation. Never tow to any height without making sure that you are legal.
14.7 Slope Soaring
(a) Slope sites are often used by many people other than model flyers. Always ensure that flying is permitted on your selected site. Note that an increasing number of slope sites are being used on an exclusive basis by clubs who may be paying considerable fees for the privilege. Keep away from paths used by ramblers and climbers and make sure that you do not frighten or disturb any animals.
(b) If the site is regularly used or overflown by full size gliders or hang gliders, then you should attempt to contact them and arrange shared use of airspace and land. We all have airsports participation in common and discussion is better than confrontation. Advice is available from the Association's Leicester office along with details of an agreed code of practice for shared sites.
(c) If a frequency control system is operating on the site, you MUST use it. If no control is operating you must not switch on your radio until you have checked that it is safe to do so.
(d) To avoid possible interference, pilots should attempt to keep reasonably close together. If this is not possible (i.e. if a pilot does a cross-country flight) then everyone on the slope should be made aware of the fact.
(e) Be aware of the turbulence immediately behind the apex of the slope. With high wind conditions and/or steep slopes this can be severe. If necessary, land either slightly down-slope or well back in the lee of the hill.
(f) Specific guidelines for the flying of slope combat, covering models, flying sites and legal requirements, are available from the BMFA Leicester office. These contain important advice and information for the slope combat flyer and should be considered essential reading if you fly this type of model. Be aware, though, that this is a legal activity if carried out on suitable sites and with care taken to avoid the endangering of other people on the slope.
(a) The first and most important principle of electric flight ground safety is to understand that the instant you start to plug in the flight battery, the model you are holding may transform itself from a dead airframe into one with its motor running at full revs and all controls moving. No matter how good your other safety checks, you must be prepared for this to happen every single time you start to connect the flight battery.
(b) Since plugging the flight battery in is nearly always a two-handed job you must give serious thought to how your model will be restrained BEFORE it does something you don’t expect. When plugging in the flight battery, positive restraint, either by a helper holding the model or by some other method and staying completely clear of the propeller must always be part of your regular routine.
(c) Electric motors have very different power and torque characteristics to normal i/c model engines. You must take very great care when setting up their control systems and handling them as an accident, such as the propeller hitting your hand, which would stall a glow engine might just make an electric motor turn harder.
(d) Developing technology has made it much more acceptable to use battery eliminator systems (BECs) to save the weight of a receiver battery, especially in lightweight installations using two or three small servos. You should not use BEC in an installation where servo battery drain may be high or prolonged, for instance with four or more servos or with standard servos in a thermalling electric glider. Also, many older BEC systems are not as reliable as the modern equipment and in all these cases the use of a separate battery is still considered to be the safer choice. The decision is yours but if you have any doubts then you should use a separate battery. It should be noted that the use of BECs will not invalidate your insurance.
(e) Always check that motor operation does not interfere with the R/C equipment in the model. Range checks with the motor off and with it on will highlight any problems. Suppression of a brushed motor is a simple task and you should seek the advice of an experienced flyer on the subject.
(f) All connectors and cables should be robust enough to carry safely the current for the motor/s used. Wiring used for small motors will reduce the power of larger motors and may run dangerously hot. If you change a motor, check that the wiring is adequate for the new one.
(g) Batteries:- Ni-Cd or Ni-Mh fast charge cells and larger Li-Po packs can be discharged at very high currents (up to 100 amps and more). Short circuits, faulty wire insulation or loose contacts can result in very considerable heat generation and may cause fires.
(h) The standard two pin polarised connectors supplied with many ‘buggy’ type battery packs are only suitable for small to medium current draw as they can offer significant resistance at times and have been known to overheat badly. There are other specialist connectors, especially the readily available gold plated ‘bullet’ connectors (available in various sizes from 2mm upwards), which are much better as they offer very low resistance and are designed to carry high currents.
(i) Always ensure that flight batteries are securely fixed and that they cannot move in flight.
(j) Many speed controllers have a specific ‘arming’ sequence, which is a pre-programmed sequence of actions that have to be followed before the motor will respond to throttle stick movements. For instance, after switching on the transmitter and receiver and then plugging in the main flight battery, one type of controller requires that you move the throttle stick from low to full throttle and then back to low before the motor is ‘armed’ and ready for flight. You must be fully familiar with the system fitted to your model.
(k) You must pay particular attention to the ‘throttle to low – transmitter on – receiver on’ sequence and be aware that the model you are holding will be ‘live’ as soon as you start to plug in the flight battery, no matter what controller arming sequence you may then have to go through.
(l) The setting of the failsafe to, as a minimum, reduce the engine(s) speed to idle, obviously applies to all electric models too. However, given the ability to re-start the motor(s) at will, it makes sense to have the failsafe cut the motor(s) completely. This will give you the desired ‘minimum power’ situation and will avoid you having to decide on what idle speed you might need to set.
14.9 Control Line
Control line model aircraft are physically constrained and therefore exempted from the requirements of CAP 722, including Operator Registration and Remote Pilot Competency, provided that:
- The length of the tether line(s) does not exceed 25m
- The MTOM is less than 1Kg
- The aircraft is not capable of vertical take-off/landing or hovering (such as helicopters or multi rotors).
In addition, our Article 16 Authorisation exempts Remote Pilots of control line aircraft from the competency requirements altogether, though they will still be required to register as an Operator if their aircraft has an MTOM greater than 1Kg.
Control line aircraft may be operated within an aerodrome Flight Restriction Zone (FRZ) without permission, provided that:
- The length of the tether line is less than 25m
- The flight does not take place within the Runway Protection Zone
- The MTOM is less than 7.5Kg
- The flight does not take place over or within the boundary of the protected aerodrome, unless permission has been obtained (in accordance with Article 94A of the ANO).
Additional considerations for safe operation include:
(a) Always use steel lines of sufficient strength for the type of model you are flying. Where possible, stranded lines should be used when flying over grass or when the model is going to be manoeuvred.
(b) If swivels are used between the control handle and the lines they must be of substantial construction. Do not use the thin bent wire type.
(c) Before each flying session and after any heavy landing, the model should be subjected to a pull test of at least 10 times the model's weight.
(d) Before every flight check the lines and linkages thoroughly. If any damage is found, DO NOT FLY until it has been rectified and re-tested to your satisfaction.
(e) Ensure that there are no spectators near to the circle before you release the model.
(f) Do not fly near ANY overhead cables. Even the low level distribution cables on wooden posts carry lethal voltages which can ‘jump’ many metres to your control lines. KEEP WELL AWAY.
(g) Control lines make good lightning conductors. Do not fly in thundery weather.
(h) Whenever high pulls are expected, use a safety strap connecting the handle to your wrist.
(i) Never release the control handle when the model is flying.
(j) Encourage spectators to stand upwind of the circle.
(k) Always mark a centre spot for your circle, ensuring that adjacent circles are not too close to each other.
(l) Always stay on the centre spot when flying.
(m) If someone strays into the circle whilst you are flying, fly high to avoid them and stay high until the circle has been cleared.
(n) Always ‘ditch’ your model rather than hitting someone.
14.10 Free Flight
Our Article 16 Authorisation defines free flight as:
A free flight model aircraft cannot be remotely piloted and does not have software or systems for autonomous control of the flight path. A flight termination device may be fitted. The aircraft trim is adjusted prior to flight. The aircraft is trimmed (and fuelled if applicable) with the intent that it will follow a substantially circular path relative to the air and ultimately glide to a low velocity landing. A free-flight unmanned aircraft will drift relative to the user depending upon the speed and direction of the wind. The person in charge of the free-flight unmanned aircraft is deemed to be the remote pilot for the purposes of this authorisation.
(a) Prior to launching their aircraft, the remote pilot should take into account the expected performance of the aircraft, the weather conditions and the availability of any flight termination device and must be reasonably satisfied that the expected flight path will not infringe an FRZ (unless prior permission has been obtained) or other airspace restriction.
(b) The operation of a free flight model aircraft must only be carried out within the limits of our Authorisation (or alternatively within the requirements of the Open Category, especially for those aircraft with an MTOM of less than 250g).
(c) A free flight model should not be deliberately flown beyond visual line of sight.
(d) A free flight model aircraft must only be launched:
- From an area free from uninvolved persons (Uninvolved persons are those who are not participating in the UAS operation or who are not aware of the instructions and safety precautions given by the UAS operator).
- When the remote pilot has identified an area (the ‘flight volume’) within which they believe the aircraft will remain.
- When the remote pilot is reasonably satisfied that the aircraft will remain within the flight volume.
- When the remote pilot is reasonably satisfied at the point of launch that no uninvolved persons will enter the flight volume and be endangered.
(e) Always launch models, particularly powered ones, well away from and downwind of any spectators or vehicles.
(f) When a fuse type dethermaliser is used, always use a snuffer tube.
(g) Check flying surface alignment and, if your model employs them, the dethermaliser and any automatic systems fitted thoroughly before launching.
(h) All glider launches should be undertaken with the towline detached from the hand winch.
(i) The use of radio dethermalisers (RDT) in free flight models is positively encouraged. Having control of when the model is DT’d provides the benefits of bringing the model down away from trees, buildings and other hazards. It also helps to keep the model within the confines of the flying site.
14.11 Indoor Free flight
(a) Free flight aircraft operated indoors or in a location in which there is no possibility of it escaping into the ‘outside’ airspace are physically constrained and therefore outside the scope of our Article 16 Authorisation or CAP722.
(b) Take care when launching that no one is standing in the flight path of the model.
(c) If your model hangs up at height, take great care when retrieving. If you have to climb to get the model, use ladders and get someone to hold them steady. Do not over-reach, take foolish risks or take on tasks that are beyond your ability. If you are flying in the larger sites such as the Cardington airship sheds, professional help is usually available and should be used.
14.12 Indoor Radio Control
(a) Radio control aircraft operated indoors or in a location in which there is no possibility of it escaping into the ‘outside’ airspace are physically constrained and therefore outside the scope of our Article 16 Authorisation or CAP722.
(b) Many of the precautions for outdoor R/C club flying can be used to ensure safety.
(c) It is not advisable, except under exceptional circumstances, to have free flight and radio control flying at the same time.
(d) Active transmitter control should be in operation throughout the meeting and at larger events a transmitter pound should be used.
(e) You should take note that some indoor specification receivers may not have the performance of standard receivers and should be prepared to limit the available frequencies to 20 kHz spacing for some sets.
(f) The pits area should usually be situated along the shorter wall next to the door and you should, if possible, use netting to isolate the pits area from the flying. Pilots should stand together in front of the nets.
(g) A ‘duty pilot’ should always be on duty to act a flight marshal. This may not be the same person for the whole event but, whoever it is, they must have the authority to ground any persistently unsafe pilots.
(h) The duty pilot should decide on the number of aircraft to have safely in the air and which direction the circuit to be flown should be.
(i) A written event briefing sheet should be given to all pilots if staggered arrivals make a pilots briefing impractical.
(j) The size of the venue will limit the size of model allowed to fly but as a general rule for a larger hall you might consider a maximum weight of 200 grams and a maximum wing loading of 15 grams per square decimetre (just over 7 ounces and 4.5 ounces per square foot).
14.13 Models Between 7.5 kg and 25 kg – General (Large Models)
(a) Any model aircraft (that is, either power fixed-wing, glider or helicopter) with a maximum take-off mass (MTOM) between 7.5 Kg and 25 Kg may be operated within the terms of our Article 16 Authorisation.
(b) Pilots of large radio control models should be aware that such models may have different operating characteristics to smaller models, several of which may not be initially apparent.
The greater mass and inertia of the large model, its generally more robust (less compliant) structure and the differences in aerodynamic efficiency of larger flight surfaces can mean handling characteristics nearer to full size aircraft than to models. You may be caught out if you are not aware of this.
You may also have visual perception problems caused by the size of the model. This usually takes the form of the aircraft being much further away than you think and can cause positioning problems in flight and danger on landing due to the large ‘swept' area on the approach. Be aware of this problem, especially when flying at low level.
(c) When constructing the model ensure that all parts have adequate strength for the task they perform. Pay special attention to the way in which wing load stresses are transferred between the wing structure and the fuselage. Tailplane members, if detachable, should have a positive lock to their mounting so that they cannot be shed in flight.
(d) Never use long unsupported control rods to the control surfaces or plastic clevis connectors as control forces will be high. Wherever possible each aileron should have its own servo and the elevator should preferably have two independent servos with either (a) mechanical interconnection so that either can drive the control surface (with reduced movement) should the other fail or (b) each servo should drive one half of the elevator through separate pushrods.
(e) Pay particular attention to the state of the battery and the switch harness. Ensure that the batteries in both the model and the transmitter have adequate capacity for the flight to be undertaken and are fully charged for each flying session. Don’t expect a standard receiver battery pack to cope with the demands of high power servos and large control forces. Loss of battery power is the most frequent cause of system failure. There are commercial battery back-up systems available and circuits have been published for similar systems. These should be seriously considered if overall servo current drain is likely to be very high.
(f) A radio fail-safe device must be fitted and operational to all models over 7.5 Kg. Remember that the purpose of the device is not to land the model but to prevent it from flying away in the event of radio failure. You should test it regularly as part of your pre-flight checks.
(h) It is recommended that all ‘large model' pilots should hold the BMFA ‘B' certificate or a similar qualification (e.g. SAA Silver Wings or LMA Proficiency Test), and should ensure that both adequate third party insurance is operational and that all flights made comply with our Article 16 Authorisation.
(i) Only operate large models at appropriate sites which allows safe separation distances from uninvolved people to be maintained in accordance with our Article 16 Authorisation.
(j) Above all always fly sensibly, safely and within your own limits.
14.14 Large Power Fixed Wing
(a) The fail-safe device fitted must, as a minimum, bring the engine to idle speed.
(b) Pay particular attention to vibration proofing the airframe. Larger engines may produce high amplitude low frequency vibration unlike that normally associated with model aircraft engines. Ground test the airframe under full power until you are satisfied that nothing will loosen in flight.
(c) Take No Chances With a Running Engine. The greatest care should be taken when running the engine of a large model. Full-size aviation standards of safety and awareness must be exercised whenever you start, run and adjust the settings of the engine.
14.15 Large Helicopters
(a) The fail-safe device fitted must, as a minimum, bring the engine to idle speed.
(b) The greatest attention must be paid to the effects of vibration on the airframe and radio installation. Linkages must be regularly checked and any that are suspect must be renewed.
(c) Because of the high airframe density and lifting power of modern helicopters, it is very easy to be operating a model weighing over 7.5 kg without being aware of the fact. Pilots are recommended to weigh all helicopters powered by ‘40’ sized engines and above and to make certain that you are complying with any current CAA regulations if necessary.
14.16 Large Gliders – Slope and Thermal
(a) Considering that the purpose of the fail-safe device fitted is to avoid a flyaway, it is recommended that it should be set with that in mind. Activation of spoilers, crow brakes or even the elevator to full up and the rudder to full left (or right) would be appropriate.
(b) Many large gliders have scale ‘bolt on’ wing fixings. Pay strict attention to how the wing load stresses are passed from the wing skins and spars through any such fixings to the fuselage.
(c) When flying from the slope be sure that you give audible warning to spectators, assistants and other pilots when about to launch or land. Agree a flight pattern to be used along the slope with other pilots or follow local rules. Always turn away from the hill at the end of each pass.
(d) Do not operate large gliders in the same airspace as other users, e.g. full-size gliders, aircraft, hang gliders etc. (see the earlier section on ‘mixed sites’).
(e) Always perform aerobatics well away (not less than 50 metres) from people or property and never, under any circumstances, overhead.
(f) In accordance with the terms of our Article 16 Authorisation, large gliders over 7.5 Kg (but not exceeding 14 Kg) may not be flown at a height greater than 120m above the remote pilot but may be flown at a height exceeding 120m above the surface directly beneath the glider.
14.17 Models Over 25 kg
Models over 25 kg are subject to the issue of an LMA ‘Certificate of Design and Construction’ exemption certificate before they may be test flown within the conditions defined in the LMA’s Article 16 Authorisation.
Subject to satisfactory completion of the test flights, the LMA will then submit the certificate of design and construction and flight test certificate to the CAA who will issue a full authorisation.
Only the pilots named on the authorisation may fly the aircraft in public and each named pilot is required to complete the flight test schedule on the aircraft separately.
It is extremely important that anyone building or thinking of building a model that may exceed 25 kg liaises with the LMA at the earliest opportunity to ensure that they remain within the law.
14.18 Space Models
NOTE: Article 240 of the ANO 2016 (Endangering Safety of an Aircraft) applies to all rockets: the operator of a model rocket must ensure that it does not endanger a real aircraft. Article 241 also applies: the operator of a model rocket must not endanger any person or property.
(a) General – Only fly on sites that are clear and open with adequate open space downwind of the launch point and in good visibility. No person shall launch a rocket unless he has reasonably satisfied himself that:
(i) the flight can be safely made; and
(ii) the airspace within which the flight will take place is, and will throughout the flight remain, clear of any obstructions including any aircraft in flight. Models should be constructed of lightweight materials capable of meeting the minimal structural loads expected during flight. The use of metal components should be limited to the absolute minimum necessary to ensure the integrity of the rocket during flight and recovery.
(iii) Models should, for the most part, use commercially available factory-produced motors, otherwise non-commercial motors must follow the United Kingdom Rocket Association (UKRA) approved safety code. Only motors that are compliant with all relevant UK legal requirements shall be used. For further information contact either the BMFA or the UKRA.
(iv) Models should be equipped with a suitable recovery system to ensure a safely retarded descent.
(v) Motors should be ignited electrically in such a way that the operator is at least five metres from the launch point.
(b) Rockets between 160 newton.seconds (‘G’ Rating) and 10,240 newton.seconds (‘M’ Rating).
In addition to the above, article 96 of the ANO 2016 (Rockets) applies to all rockets with motive power exceeding 160 newton.seconds (‘G’ Rating) and the requirements of the article are summarised below.
No person shall launch a rocket with a motive power that exceeds 160 newton.seconds (‘G’ rating) unless he has reasonably satisfied himself that:
(i) the flight can be safely made; and
(ii) the airspace within which the flight will take place is, and will throughout the flight remain, clear of any obstructions including any aircraft in flight;
(iii) for a flight within controlled airspace, he has obtained the permission of the appropriate air traffic control unit for aircraft flying in that airspace;
(iv) for a flight within an aerodrome traffic zone he has obtained the permission of the air traffic control unit, the aerodrome flight information service unit at the aerodrome or the air/ground communications service unit as appropriate; and
(v) for a flight for aerial work purposes the flight is carried out under and in accordance with a permission granted by the CAA.
(c) Rockets over 10,240 newton.seconds (‘M’ Rating)
Large rockets exceeding 10,240 newton.seconds must not be launched unless in accordance with a permission granted by the CAA. Further details can be obtained from the Airspace Utilisation Section of the CAA (Contact the BMFA for contact details).
BMFA Notes In addition:
(i) Models must be launched from a stable platform equipped as a minimum with a launch rod for initial guidance and must not be launched at an angle of more than 30º from the vertical.
(ii) A clearly audible countdown of at least 5 seconds must be given by the launch supervisor. In the event of a misfire, do not approach the model until it is certain that ignition will not occur.
(iii) Where spectators are present, a Range Safety Officer should be appointed to take responsibility for all flying activity.
(d) Large Scale Rockets, ‘H’ to ‘M’ Motors.
Details of the operating and safety procedures for large scale high powered rockets are naturally more extensive and involved than for the lower powered ones.
A comprehensive safety code has been written by UKRA to cover such operations and is published by the BMFA. It is required reading if you are interested in large scale rocketry.
(e) Space Modelling Specialist Bodies
The BMFA Specialist Bodies covering space models are Federation Aeronautique Internationale Rocketry (FAIR) and the United Kingdom Rocketry Association (UKRA). These bodies can be contacted via the BMFA’s Leicester office.
14.19 Gas Turbines
A ‘Code of Practise for the Operation of Gas Turbines’ has been prepared by the Gas Turbine Builders’ Association and the Jet Modellers’ Association. Anyone intending to build and fly a gas turbine model should obtain and read this document before proceeding, as it covers all the essential safety procedures and additional legal liabilities concerned with this type of model. It is available for download from the BMFA web site (www.bmfa.org) or directly from the Leicester Office.
(i) The operation of gas turbines requires special care and the manufacturer’s operating instructions must be understood and closely followed. All pilots and helpers must be fully briefed on the operation of the engine before any starts are attempted.
(ii) Never run an engine in excess of the manufacturer’s recommended power rating. Always follow the manufacturer’s recommendations on pipework and fittings, especially with regard to periodic renewal.
(iii) Take extra care during the engine’s initial operating period. Until the unit is proven, do not operate it near people.
(iv) Pressurised gas fuels, such as Propane, require care in handling; spill dispersal rates can be slow and the gas can ‘pool’ in hollows or in void areas in fuselages. The liquid can also cause frostbite, if allowed to come into contact with skin.
(v) Ensure that all fuel is stored in labelled containers fit for the purpose. These containers should be no larger than necessary.
(vi) Model jet turbine installations may produce significant amounts of RF interference. In particular, fuel pumps, if they use brushed motors, and the turbines themselves, which have been known to produce significant static interference, especially if ceramic bearings have been incorporated. Make sure that you do not install receivers or servos or run aerials near to the engine installation.
(vii) All gas turbine models are required by the CAA to be fitted with a failsafe. This must, as a minimum, bring the engine to idle in the event of radio interference or failure. The fuel system must be capable of manual shut off via a fuel valve or fuel pump switch.
(viii)The use of 3D printed rotating parts is not recommended in any gas turbine operated where third parties may be put at risk. Whilst the 3D metal printing technology is advancing fast, the concern is that any contamination in the material used to 3D print a component, may significantly compromise its structural integrity/safety.
(b) Before Starting
(i) Smoking or naked flames must not be allowed near the engine and the fuelling area.
(ii) A suitable fire extinguisher (CO2 or dry powder but not water) should always be present at Start Up and for any period during which the engine is running.
(iii) The Start Up area should be kept clean and free from any loose items that may get sucked into the fan or turbine.
(iv) Ideally, the Start Up area should be on a paved surface, but if this is not possible the grass should be short and clear of all loose material.
(v) Check the integrity of any compressed air hoses, clips etc, prior to turning on the air. Manufacturer’s instructions should always be followed, particularly those relating to safety.
(vi) Gas fuelled models must never be left in the pits area fuelled up. Once fuelled up they should be moved directly to the designated start-up area.
(i) The engine should normally be started facing into wind but make sure that it is not pointed at people or the pits area. The effect of the jet blast must always be kept to the absolute minimum.
(ii) Beware of ‘wet’ starts with liquid fuels.
(iii) After starting the engine, wherever possible, check the oil flow to the bearings and the exhaust gas temperature. You should also keep a constant watch for any new noises or vibration. Any deviation from normal could indicate trouble. Do not run the engine if you are not sure.
(iv) Whenever possible a reliable helper should assist with the start. The helper should be close by and fully briefed on the operation of the engine. The helper should ensure that you are not distracted during the start sequence.
(v) Models must be physically restrained during start up. The use of wheel brakes alone is not sufficient.
After every flight ensure that the engine is fully shut down, the fuel shut-off has been operated and that any hatches are opened to assist engine cooling.
(e) Turbine Model Flight Safety Information:
(i) Adverse runway conditions can have an adverse effect on the aircraft’s performance on take-off. E.g. wet or long grass will significantly increase take-off distance.
(ii) The rate of climb at take-off weight may be significantly less than that of a propeller driven model aircraft. Care must be exercised to ensure safe clearance of any obstacles immediately after take-off.
(iii) The lack of “prop wash” over the control surfaces of a jet propelled model aircraft will result in less control surface effect particularly at low speed.
14.20 First Person View R/C
Our Article 16 Authorisation defines first person view aircraft as follows:
In First Person View operations the remote pilot flies the aircraft using images provided by cameras aboard the aircraft. When flying FPV the remote pilot cannot monitor the flight path in relation to other aircraft, persons, vehicles, vessels and structures for the purpose of avoiding collisions to the same extent as a remote pilot maintaining external direct, unaided visual contact with the aircraft.
Our Article 16 Authorisation incorporates the terms of our previous FPV exemption, but also includes specific provision for FPV ‘drone racing’ which the BMFA had been discussing with the CAA for some time.
(a) FPV Drone Racing
A model aircraft may be flown by a remote pilot using first person view subject to the terms of our Authorisation and provided that the aircraft is operated:
- Within a sterile area – meaning a cordoned off, closed area that uninvolved persons are excluded from. (Uninvolved persons are those who are not participating in the UAS operation or who are not aware of the instructions and safety precautions given by the UAS operator).
- The aircraft is not flown in excess of 160ft (50m) above the surface.
- In accordance with procedures set out for the purpose of the event and in accordance with the instructions of the race director or other nominated person, including provision of a ‘terminate race and land immediately instruction.
- Any observers are suitably briefed and aware of their responsibilities, including the monitoring of people or aircraft entering the sterile area.
Individual remote pilots do not require their own ‘competent’ observer when operating under this provision.
Further detailed guidance on the rules and requirements for FPV Drone Racing can be found in the BDRA rules (https://bdra.uk/rules/) and the FAI Sporting Code, Section 4, Volume F9 – Dronesport. BMFA variations to the FAI rules can be found in Section 5 of the BMFA Contest Rule Book.
(b) General FPV Flying
A model aircraft may be flown by a remote pilot using first person view subject to the terms of our Authorisation and provided that:
- The remote pilot is accompanied by a competent observer who maintains direct unaided visual contact with the unmanned aircraft sufficient to monitor its flight path in relation to other aircraft, persons, vehicles, vessels and structures for the purpose of avoiding collisions and advises the remote pilot accordingly.
- The MTOM of the aircraft does not exceed 3.5Kg.
- The aircraft is only operated in the areas defined in the ‘Where can I fly’ section (8.3.7).
- The aircraft is only operated in accordance with the ‘Separation Distances from Uninvolved Persons’ defined in section (8.3.9). (Uninvolved persons are those who are not participating in the UAS operation or who are not aware of the instructions and safety precautions given by the UAS operator).
And the aircraft is not flown:
- Within an aerodrome FRZ, unless appropriate permission has been obtained.
- At a height of more than 1000ft above the surface, unless it is a rotorcraft with more than 1 lift generating rotor or propeller in which case the height shall not exceed 400ft above the surface.
- Over or within 150m of any assemblies of people (Assemblies of people are gatherings where persons are unable to move away due to the density of the people present).
• Within 50m of any vessel, vehicle or structure which is not under the control of the remote pilot.
14.21 Round the Pole Flying
A round-the-pole model aircraft is an unmanned aircraft that is tethered to a fixed point by one or more lines so that its flight is constrained to the surface of a hemisphere around a central pylon/tether point with a radius equal to the length of the lines (which generally also carry the electricity to power the aircraft).
Because they are physically constrained, they are therefore outside the scope of our Article 16 Authorisation or CAP722.
Unlike control line aircraft, the remote pilot controls the aircraft from outside the operating circle with control often limited to throttle control.
Most RTP flying is conducted indoors with lines not generally exceeding 6 metres. It is therefore outside the scope of regulation.
In the unlikely event that an aircraft exceeding 1Kg were to be operated outdoors, then the Operator would be required to register with the CAA.
The remote pilot should ensure that the flying area is free from spectators and/or other obstacles prior to commencing their flight