Rules for F2D - 2011 version
HTML version by Henning Forbech - First published: 30/12 2010 - Last update: 17/2 2011
Go to the Judges Guide

4.4.1. Definition of a Combat Event
A combat event is a contest during which eliminating heats are followed by a final in which two competitors with their model aircraft fly in the same circle at the same moment for a predetermined time, the object being to cut a streamer attached on the longitudinal centre line of the opponent's model aircraft, points being awarded for each cut taken.
4.4.2. Definition of a Combat Model Aircraft
  1. Model aircraft in which the propulsion energy is provided by a piston motor(s) and in which lift is obtained by aerodynamic forces acting on surfaces which remain fixed in flight, except for control surfaces.
  2. The longitudinal centre line shall be defined as the axis of the propeller in case of a single engine model aircraft and the axis of symmetry in the case of multi-engine model aircraft.
4.4.3. Combat Site       Judges Guide
A combat site must consist of three concentric circles which shall be marked on the ground.
  1. The pilot circle:        radius 2 metres.
  2. The flight circle:       radius radius 20 metres
  3. The pitting circle:      radius radius 22 metres
The flight and pitting circles must be laid out on grass. The pilot circle may be laid out on grass or any other material. The area between the 20 and 22 metre circles is called the pitting area.

During active combat periods the pilot and his mechanic(s), officials, team managers and others within the boundary of the designated combat flying area must wear a safety helmet, with a fastened chinstrap, strong enough to withstand the impact of a flying combat model aircraft.

4.4.4. Competitor       Judges Guide
The pilot, who shall be the entrant and known as the competitor, may employ a maximum of two mechanics in any one heat. (In exceptional circumstances of wet or extremely windy weather, an additional helper may be used as a streamer holder and must perform no other function for the duration of that combat period).

For World and Continental Championships, the mechanics, a maximum of six other than team members or the team manager (or assistant team manager), must be registered for no more than one national team, from the beginning of the competition throughout to the end.

To avoid the catching of the opponent's lines the protruding parts of the helmet must be covered. No communication using electronic devices is allowed between the pilot and mechanics/persons outside the flying circle.

4.4.5. Characteristics       Judges Guide
  1. Maximum loading:                                        100 g/dm2
    Maximum swept volume of motor(s):             2,5 cm3
  2. Line length:                                                    15,92 +/- 0,04 m
    Minimum line diameter:                                   0,385 mm (no minus tolerance)
    Two multi-strand control lines must be used. No free ends capable of entangling an opponent's lines, and no line splices, are permitted. Open connection connectors are not allowed.
  3. Engines with glow plug ignition shall have their exhaust port(s) connected to silencer(s) (one or two), consisting of a simple chamber with one circular cross-section rearmost outlet aperture of 6 mm (1) or 4,2 mm (2) diameter(s) opposing the exhaust port connection. The minimum total volume of the exhaust system shall be 12,5 cm3. In the case of two exhausts, each silencer shall have a minimum volume of 6 cm3. The maximum total length of the exhaust system from exhaust port(s) of the cylinder to and including outlet(s) is 15 cm. One pressure tap directly connected to the fuel tank, of maximum diameter 2 mm, is allowed. No other openings or vents are allowed.
  4. The motor shall be naturally aspirated via a single round venturi with a maximum effective diameter of 4 mm.
  5. Any interconnecting chamber between the air intake and the induction port of the motor shall have a maximum volume of 1,75 cm3. This clearly prohibits sub-piston induction for supplementary air intake.
  6. A safety wire with a minimum diameter of 0,5 mm must be attached between the control system and the engine(s). The engine(s) must always stay connected to the lines.
  7. A safety strap connecting the competitor's wrist to the control handle must be provided by the competitor and worn at all times while his model aircraft is flying. The strap should be as shown in the sketch i.e. it should be attached to the wrist with a loop and sliding knot so that if the handle is released it will tighten itself securely around the wrist. The point of attachment at the handle is up to the discretion of the pilot.

  8. The model aircraft shall not carry any artificial aid to assist the cutting of the streamers.
  9. The model aircraft shall be equipped with a device specially designed to retain the streamer which shall be fitted on the longitudinal centre line and sufficiently strong so that the streamer shall not become detached under normal flying conditions.
  10. Standard fuel shall be supplied by the organisers to be used for practice (minimum 0,5 litre) and competition to the following formula: 10% nitromethane, 20% castor oil lubricant (first pressing) and 70% methanol. A reasonable charge may be made for the fuel.
    Note: Fuel for compression ignition engines is not restricted. Rule B.3.1. Section 4B, Sporting Code Volume ABR, does not apply to class F2D.
  11. Each model aircraft must be equipped with an engine shut-off device that stops the engine automatically if a fly-away occurs. The shut-off can be inactive at take-off, as long as it becomes active before combat starts. Once active, the device must remain functional for the entire time the model aircraft remains airborn. The device may only be used to stop the engine(s).
    Note: Rule 1.3.2. Section 4C, Sporting Code Volume ABR, does not apply to engine stop devices in class F2D as the device may be electronic and controlled via the lines or wireless.


4.4.6. Technical Verification       Judges Guide
To be tested before each heat:
  1. Each set of lines must be checked for length and diameter.
    The line length is measured from the inboard face of the grip of control handle to the longitudinal centre line of the model aircraft.
    A pull test shall be applied to the assembled handle(s), control lines and model aircraft. The pull test shall be equal to 20 Kgf.
    The processing officials or judges may ask the competitor to change the lines if there is any doubt about the line quality, such as kinks, curls, stress or rubbing marks.
  2. The intake opening shall be checked with a simple plug gauge (diameter 4,05 mm) per the following sketch:

  3. The outlet of the silencer(s) shall be checked with a simple plug gauge (diameter 6,05 mm for one silencer and 4,25 mm for two silencers) per the following sketch:

  4. Demonstration of the engine shut-off device may be required by the judges before each heat. Additional demonstrations may be requested by the judges after the heat.
  5. The safety strap(s) and safety wire(s) may be pull tested with a load equal to 20 Kgf.


4.4.7. Number of Model Aircraft
  1. Only one model aircraft specification certificate is required for each design of model aircraft presented by each competitor.
  2. Each competitor shall be permitted a maximum of two model aircraft, two handles, two pairs of lines and two engines in each combat heat. If the reserve model aircraft is used, the streamer or its remaining parts must be transferred to the reserve model aircraft. The handle plus lines for the reserve model aircraft must be placed just outside the pilot circle.
  3. Engines, control lines and handles may not be replaced or interchanged during the combat period.


4.4.8 Streamer       Judges Guide
The streamer shall consist of double weight crepe paper (80 g/m2) or any replacement of equivalent strength, not less than 2,25 m or more than 3 m long and 3 +/ 0,5 cm wide, fixed to a sisal (or any replacement of equivalent strength) string of 3,25 m minimum length. All streamers must be of the same length. There shall be a clearly visible ink mark 2,5 m from the junction of the string and streamer. The streamer shall be attached to the model aircraft in such a way that the ink mark is level with, or behind, the rearmost portion of the model aircraft (see sketch). The attachment part of the string shall have a minimum length of 0,75 m. The attachment end of the streamer shall be reinforced on either side by tape approximately 2 cm wide affixed diagonally to the length of the streamer with one at right angles to the other and extending for a maximum of 5 cm. An additional fibre/fabric reinforced tape 2 cm wide is affixed across the streamer (see detail below).
The colour of the streamer must be different for the two competitors in the heat. Each pilot/pit crew shall be issued with a streamer before the start of the heat by the judge assigned to that competitor. A new streamer will be available from the judges when needed.

4.4.9. The Heat from start to finish       Judges Guide
  1. All signals shall be both acoustic and visual.
  2. During the starting period the launching positions must be separated by at least a quarter of a lap The first named competitor in the draw shall have the choice of streamer colour and the other the choice of starting position.
  3. It is the responsibility of the pilot/mechanics to make sure the streamer is unrolled before take-off.
  4. The motor(s) must be started by flicking the propeller by hand.
  5. A first signal, given by the Official Timer, shall signify the beginning of the 30 seconds period when the mechanic(s) or the pilot have the opportunity to start, run and adjust their motors.
  6. A second signal, given by the Official Timer, shall signify the beginning of the combat heat period on or after which the model aircraft may be launched.
  7. From the moment the Official Timer has given the signal to launch, the combat heat lasts for a maximum of 4 minutes.
  8. When the Circle Marshal is satisfied that each model aircraft has completed two level laps, anticlockwise, separated by approximately half a lap, he will give a signal that combat may begin.
  9. Following an interruption when one or both model aircraft have been grounded, combat may restart after a signal from the Circle Marshal. This signal shall be given as soon as the Circle Marshal is satisfied that there is approximately half a lap separation between the two model aircraft.
  10. If, after a mid-air collision, no streamer can be found and the streamer retaining device is missing or bent, then, with the permission of the judges, it is acceptable to continue the heat without replacing the streamer.
  11. Only the streamer/string may be moved around the circle by the mechanics/pilot. Models in the pitting area may not be moved, except to open a safe distance (approximately 5 metres) away from the opponent's mechanics. Unless otherwise directed by the judges, it is the rearmost team's responsibility to move back before pitting. Under conditions of heavy wind, the Judges can allow models with a non-running engine to be moved to a safer starting position.
  12. When moving around the circle the mechanics/pilots must be on the outside of the pitting circle. Within the pitting area and flight circle, mechanics may only move radially inward and outward.
  13. If, as a result of a mid-air collision, the silencer is detached and the model aircraft remains airborne, the heat may continue. After a landing, however, the silencer must be replaced before the model aircraft can be used again.
  14. The Circle Marshal will monitor the conduct of both pilots, and shall issue a yellow card warning to any pilot who uses a rough or unsafe flying style, causes line tangles, or displays unsportsmanlike behavior. Each yellow card issued (a maximum of three for each pilot, per competition) shall be efficially recorded and retained for the remainder of the competition. Initial and subsequent offences during a competition are to be penalized in accordance with 4.4.12.A and 4.4.12.C, respectively. If the first yellow card incident is considered severe, the pilot shall also be disqualified for this offence.
  15. The Circle Marshal shall signal both pilots to fly leveland anti-clockwise and to cease combat when both streamer strings have been cut. If one pilot has only string remaining he may request the circle marshal instruct both pilots to fly level and anti-clockwise and to cease combat.
  16. The Circle Marshal shall give an acoustic signal to terminate the combat heat:
    1. 4 minutes after the signal to launch (10 seconds countdown).
    2. if the heat has to be terminated due to disqualification of one or both competitors or for any other reason.


4.4.10. Scoring       Judges Guide
  1. Scoring shall start at the signal to launch and continue during the heat.
  2. 100 points shall be awarded for each distinct cut off the opponent's streamer. There is a cut each time the model aircraft, propeller or lines fly through the opponent's streamer resulting in particle(s) becoming detached from the streamer. A cut that contains string only does not count.
  3. Two points shall be awarded for each second that a model aircraft is airborne during the heat. In the case of a model aircraft fly-away the watches should be stopped from the moment of the fly-away.
  4. Each penalty point given (See 4.4.12) shall be subtracted from the competitor's score.
  5. In the event of a tie score in any heat, that heat shall be re-flown. A heat is considered a tie if the score difference is 10 points or less.


4.4.11. Reflights       Judges Guide
A reflight may be granted:
  1. In the event of a line tangle resulting in the control line(s) breaking and only one model aircraft being grounded, making it impossible to clear the line tangle.
  2. If, as a result of combat, a model aircraft cuts its own streamer/string or the streamer/string becomes wrapped around the model aircraft and/or the lines (unless only string remains).
  3. at the discretion of the Judges/Circle Marshal if an unfair situation occurs and none of the pilots/mechanics can be blamed.


4.4.12. Penalties and disqualifications
A. A competitor will receive a penalty of 40 points:       Judges Guide
  1. if he steps outside the pilot circle with one foot while his model aircraft is airborne.
  2. if the mechanics enter the flying circle at an oblique angle or cut across the flying circle to reach a downed model aircraft. One penalty only will be given for each offence even if more than one mechanic is involved.
  3. if the mechanic(s)/pilot do not immediately, or after a clearing a line tangle, withdraw a grounded model aircraft to the pitting area prior to servicing it. It is not allowed to service the model or remove the streamer until any line tangle is cleared.
  4. if the model aircraft is launched prior to the starting signal.
  5. if the mechanic(s)/pilot allows both engines to be running at the same time during the flight period. Brief bursts, not longer than 10 seconds to warm the engine with a prime or to clear a flood is permitted. Running the engine from the tank is not permitted.
  6. when he receives his first yellow card (Subject to 4.4.9.n).
B. A competitor will receive a penalty of 100 points:       Judges Guide
  1. if the streamer does not cleanly unfurl upon launching the model aircraft.
  2. if the mechanic(s) damage the streamer or allow the model aircraft to cut its own streamer whilst still on the ground, and launch the model without replacing the streamer.
  3. if the string becomes detached from the model aircraft while airborne prior to the signal to start combat.
  4. if the silencer falls off during the flight or ceases to operate.
In all these cases the pilot must immediately on a signal from the Circle Marshal land and unfurl/replace the streamer or replace the silencer. The watches should be stopped at the moment the pilot is asked to land.  

C. A competitor will be disqualified from the heat:       Judges Guide
  1. if he flies with a model that does not conform to 4.4.5.
  2. if his model aircraft fails to become airborne within two minutes of the signal to launch.
  3. if he attempts to fly a model aircraft which at the time of launch does not have a:
        i)   strong effective control mechanism
        ii)  secure engine attachment
  4. if he deliberately attacks the streamer of his opponent's model aircraft prior to the Circle Marshal's signal to start combat.
  5. if he interferes with his opponent, or forces his opponent to leave the pilot circle.
  6. if, while his model is not airborne and his opponent is flying or ready to fly, he leaves any parts of his model or lines in the pilot circle without an immediate attempt to clear them.
  7. if he attacks his opponent's streamer without his own, or the remaining parts, attached to his model aircraft (Except for 4.4.9.j).
  8. if he is not present at his allotted flight time, unless he has the express permission of the Event Director.
  9. if he leaves the pilot circle, intentionally while his model aircraft is flying.
  10. if he leaves the pilot circle without informing his opponent of his intention to do so when his model aircraft is grounded for a purpose other than to pick up the lines of the reserve model aircraft or to allow his model aircraft to be serviced.
  11. if he flies in such a manner as to inhibit his opponent, or his opponent's pit crew, from clearing any line tangle.
  12. if he flies other than level in an anticlockwise direction when only his model aircraft is airborne and there is no line tangle. Sudden or rough manoeuvres are not allowed.
  13. if he fails to clear any line tangle prior to launching his reserve model aircraft unless both he and his opponent have informed the Circle Marshal that they have agreed to continue the heat without clearing the line tangle. In this event the Circle Marshal must agree to the continuation, only doing so when he is satisfied that it is safe to continue.
  14. if he releases the handle and the safety strap separates from handle or wrist or he removes the safety strap, for any reason, while the model aircraft is flying.
  15. if he interferes to cause a ground hit of, or collides with his opponent's model aircraft that clearly has no streamer left and flies level in anticlockwise direction without any manoeuvres to chase and attack.
  16. if the streamer becomes detached from the streamer retaining device during combat, but not as a result of a mid-air collision.
  17. if the model aircraft lands with no streamer string, unless the streamer retaining device is missing or bent as a result of a mid-air collision.
  18. if, during a line tangle where one or both models remain airborne, his mechanic(s) enters the flying circle.
  19. if, in the event of a flyaway, his engine shut-off device does not activate.
  20. when he receives his second or third yellow card (Subject to 4.4.9.n)
  21. for any other flagrant breach of the rules.

4.4.13 The use of Video equipment       Judges Guide
The Organiser/Judges may use a Video recording equipment to monitor the pilots and the pilot circle. At the discretion of the Judges/Circle Marshal the officially recorded video can be used as a judging tool.

4.4.14 Individual and Team Classification       Judges Guide
  1. The contest shall be run as a knockout tournament.
  2. The competitor who obtains the highest score in points shall be the winner of each heat.
  3. A competitor shall be eliminated from the competition when he has lost two heats.
  4. Each round shall be randomly drawn (subject to 4.4.14.e)) from the competitors remaining in the competition.
  5. Previous opponents and competitors of the same nationality shall be drawn apart if possible with competitors of the same nationality to fly against each other only if there are no remaining opponents. Defending champions, not members of their national team, are considered as individuals not possessing any specific nationality.
  6. In a round with an odd number of competitors the non-flying competitor will fly twice in the following round, in the first heat and in the last heat (if the number of competitors permit it and he still is in the contest).
  7. Each competitor shall be ranked according to his number of wins, not counting fly-off heats, with the fly-off heats being used to establish second and third place as necessary.
  8. In the event of a tie for second or third place, the equal placed flyers shall take part in a fly off, during which they shall be allowed only one loss. In the event of a tie for third place after a fly-off for second place then there shall be a new fly-off for third place.
  9. A specific junior final tournament will be organised if juniors are at the same placing (tie) in the general tournament, in order to define who is first, second and third for the specific individual placing and will have no influence on the general individual placing (no change in the team classification).
  10. The competitors "win" scores, not counting fly-offs, shall be added for the participants of each nation.
  11. The team classification is established by taking the total scores, obtained in 4.4.14.g) above, of the three best scoring members of the team together. In the case of a team tie, the team with the lower sum of place numbers, given in order from the top, wins. If still equal, the best individual placing decides. Complete three-competitor teams are ranked ahead of two competitor teams which, in turn, are ranked ahead of single competitor entries.

4.4.15. Judges and Timekeepers       Judges Guide
  1. The organisers shall appoint a panel of three judges who shall be selected from a list of persons proposed by National Airsport Controls for their proficiency and experience and approved by the CIAM. The judges must have at least one language in common. At World and Continental Championships and other limited entry international competitions the judges must be of different nationalities. In open international competitions the judges must be of at least two nationalities and only two of them must be approved by CIAM. At World Cup and other Open International Competitions one of the judges and the Circle Marshal can be the same person.
  2. Three timekeepers/scorers shall be allotted to each competitor for World and Continental Championships, two for Open Internationals.


Go to the Rule Book

Purpose of this Guide
This Guide is intended as an aid for Judges/Circle Marshals, Officials and Organisers as well as Competitors of how to interpret, understand and use the Sporting Code Rules concerning F2D Combat. Most of the content in this guide could also be used for class F2E.

Processing (before the contest)
At processing, before the contest, the following issues can be checked and/or tested: Note: Although checked at processing this is not a certificate that a competitor's equipment can't be a source of disqualification in the competition.
Rule 4.4.3. Combat Site       Rule Book
If the centre (pilot) circle is laid out on other material than grass it is recommended that this material have a maximum radius of 4 metres although the pilot (centre) circle must be marked with a radius of 2 metres.

Circles are best marked using white paint or chalk but also plastic strip can be used. In the case of using plastic strip the organiser must make sure it is laid out and fastened in such a way as not to cause a trip hazard to pilots or mechanics. Plastic strip should be avoided when marking the pilot circle.

Contestants not directly involved in the organisation or flying in a heat are always requested to withdraw behind the safety fences or outside the contest area. Spectators and others not involved in the Combat

Contest must at all times stay behind the safety fences or at the allotted places.

The organisers should provide special safety fences for the Scorers/Time Keepers. Judges and Team managers should also use this safety measure as intended when flying is in progress.

The safety strap and shut-offs must be used at practice flights.
Rule 4.4.4. Competitor       Rule Book
There is no rule saying that the mechanic(s) must be of the same nationality as the competitor. This means that a single competitor from a country can find and employ mechanics at the World or Continental Championships. The only demand is that they possess a valid Sporting License and are not registered for another National Team.

When the pilot is outside the centre circle for other reasons than picking up the handle or waiting for his model to be serviced all rules that apply to mechanic(s) also apply to the pilot.
Rule 4.4.5. Characteristics       Rule Book
b) All handle and line connections should be covered in such a way not to interfere with the opponent's lines but not longer than necessary to cover the connectors. More than one connector per line at the handle and at the model aircraft is not permitted. Note that open connection connectors are not allowed (see sketch). Pilots using this type of handle must tape the handle before the heat.

f) There must always be a wire connection between the engines and the lines.
k) When referring to the engine shut-off (engine stop) device this cover both the anti fly-away device (shut-off) and the system used to stop the engine at the pilots will.
Rule 4.4.6. Technical Verification       Rule Book
d) Demonstrations of a working shut-off can be requested at random.
e) When pull testing the safety wire it is recommended to ask the competitor (owner of the model) in what direction to pull.
Rule 4.4.8 Streamer       Rule Book
The mechanic(s)/pilot can not ask for another streamer just to save time in a heat, for example if it is wrapped around the lines.
All parts of the opponent's streamer/string should be cleared from your own streamer/string before relaunching.
No matter if the competitor uses a metal ring or not to attach the streamer to the model, the string should have a single loop and one knot.
Rule 4.4.9. The Heat from start to finish       Rule Book
f) When the model is launched the pilot should walk directly into the centre circle. It is the responsibility of the competitor to make sure where the Circle Marshal is to avoid running into him.
h, i) At take-off and before the signal to start combat the models should fly level in an anti-clockwise direction. The competitors are not allowed to do any loops or other manoeuvres unless asked to by the Circle Marshal in order to separate the models. Take-off should take place in level flight forward, not upwards or backwards. Any break of these rules will result in a disqualification.
k) In conditions of heavy wind, a grounded model which does not have a running engine may be moved to a safer launching position under supervision by the Judges. While doing this, the mechanics are not allowed to carry the model aircraft and lines over an opponent's grounded model aircraft and/or pitting crew. Parts of a crashed model aircraft are not considered a grounded model aircraft.
l) The mechanic(s)/pilot may move around in the vicinity of their pitting position.
n) The pilot will receive a yellow card if he uses a rough or unsafe flying style, causes a line tangle or shows unsportsmanlike behaviour. The Judges/Circle Marshal shall not hesitate to give a yellow card to keep the level of combat on an acceptable and fair level. A yellow card can be given during the heat or after the heat when the Judges/Circle Marshals have had a chance to confer about situations in the heat. The first yellow card is a 40 point penalty while the second and/or third yellow card is a disqualification. If the first yellow card incident is considered severe, the pilot shall also be disqualified for this offence.
o) The scorers must be observant and aware that the heat can be stopped.
Rule 4.4.10. Scoring       Rule Book

c) The scorer's times should be rounded to the nearest whole second and then added together. The added result should be divided by the number of scorers, and then rounded to the nearest whole second. This result should be the competitor's official time in the heat. If any scorer's time shows a significant deviation from the average, it should be excluded (but still noted on the score sheet). The scorers must be observant and stop their watches if there is a fly-away of the model they are scoring.
Rule 4.4.11. Reflights       Rule Book
c) A reflight may be granted if, for instance, the model is stuck high up in a tree or in a safety net where it will take too long, or be impossible to retrieve the streamer.
  Rule 4.4.12. Penalties and disqualifications
A. A competitor will receive a penalty of 40 points:       Rule Book
a) No penalties should be given to the pilot if he is pushed out of the circle. Instead his opponent should receive a yellow card or be disqualified (4.4.12.C.e) unless the Circle Marshal consider it an accidental incident where neither of the pilots can be blamed.
b) In order to reach a grounded model the mechanics are not allowed to cut across the flying or pitting circle (See sketch). If a model is crashed close to the centre circle it is especially important for the mechanic(s) to be observant at what point to enter the circles. A penalty should be given if, for example, the pilot picks up the crashed model on one side of the centre circle and brings it out on the opposite side of the circle.

c) Be observant that all line tangles must be cleared before the model is serviced or the streamer is moved to the spare model (Except for the case where both pilots have the permission of the Circle Marshal to continue). This rule is also valid if the model is outside the flying circle, for example due to a fly-away.
f) See 4.4.9.n.
B. A competitor will receive a penalty of 100 points:       Rule Book
a, b, c and d) The scorers must be observant and stop their watches if this happens for the model they are scoring.
C. A competitor will be disqualified from the heat:       Rule Book
a) This means that a model without a silencer, a working shut-off, a streamer hook etc can not be used again until repaired.
c) For safety reasons it is not allowed to attach tools, weights etc to a crashed model to compensate for a lost outer wing.
f) If lines or handles are dragged into the centre circle by accident the Circle Marshal should order the pilots to cease combat and fly level until the circle is cleared and it is safe to continue.
h) It is the responsibility of each competitor and his Team Manager to be aware of when his flight is scheduled.
m) Crossed lines which do not interfere with the course of the heat are not a problem and is no reason for disqualification. If the spare model aircraft is needed to take-off and it is prohibited by the crossed lines of the opponent then another situation is created and rule 4.4.12.C.u is applied: Interference with his opponents equipment.
o) When a pilot without a streamer chooses to fly level and combat still is going on, and his opponent flies in such a way to cause a crash or collision he will be disqualified.
p) This situation must be carefully watched by the Judges and if the streamer/string can be suspected to have been hit or partly cut in a previous attack or mid-air collision it should be counted as a cut for the opponent.
q) A part of the string must always be attached to the streamer retaining device. Only the metal ring (if used) is not enough. If the streamer retaining device is bent or missing due to a mid-air collision the pilot should not be disqualified. Also, if the string is missing and device is intact but the model is damaged close to the device and it can be concluded that the string is cut in the loop no disqualification should be given.
t) See 4.4.12.A.f.
u) For example such as tampering with the streamer (putting water, saliva or fuel on the string before tying the loop, additional single knots on the string wherever, cause damage or weak spots on the string by pulling with the teeth, pliers or scissors , soaking the paper with fuel, pre-cut, the paper, etc).
This rule can also be used to disqualify a competitor due any other breach of the rules that is not covered in a separate paragraph.
Rule 4.4.13 The use of Video equipment       Rule Book
Note that is only the Judges/Circle Marshal/FAI Jury that can decide if they want to look at the video recording or not. A competitor can make a request or give in a protest after a heat but if the Judges/Circle Marshal feel certain, they should not be obliged to look at the video recording.
Rule 4.4.14 Individual and Team Classification       Rule Book
f) Although this competitor will fly his heat in the following round his score will count to the round where he was the odd one.
i) Do a fly-off following the rules in 4.4.14.h.
Rule 4.4.15. Judges and Timekeepers       Rule Book
a) It is of most importance that the Judges have a good understanding of the rules and that they have a common language as this will reduce delays and possible errors. The Circle Marshal has the main responsibility for the centre circle and the pilots and their behaviour although all Judges have the right to give penalties. Penalties can always be given after a heat where the Judges/Circle Marshal have had a chance to discuss situations that occurred in the heat. In case of three Judges one should be assigned to each pilot and his mechanic(s) while the third Judge will have an overall function. The Judges must work together and watch any models landing/crashing close to them.
b) All scorers should count cuts as well as record airtime for the competitor. Every scorer should have a notepad where he/she can make records of the number of cuts as well as the air time (after the heat). A good way is to divide the six scorers into three groups of two and spread them around the circle. Each group will consist of a scorer for each pilot and they should be instructed to talk to each other during the scoring. If, after the heat, the scorers have a different cut count they must conference and try to come to a decision. They also have the possibility of asking the Judges for advice.