F3G - Rules

After a long Corona break, we had a total of 6 F3G competitions in 2021 and 2022.

These have shown that we have created an exciting, challenging and interesting new model flight class with F3G. However, it has also been shown that some rules should be improved and formulated more transparently. Once again a big thank you to all the input from the many F3G pilots.

The following rule adjustments regarding F3G are therefore pending for 2023. These have already been approved by the CIAM Technical Committee.  During the CIAM Plenary Meeting on April 1, 2023  the final decision will be made if they are applied and included into the F3G Rules 2023-.

In the following post I would like to introduce the still very young class F3G.

The official and current regulations can be found at the FAI under the link Volume F3 Radio Control Soaring Model Aircraft . Since it is in English and a bit awkward to read, I will try to describe the main rules and the current experiences in the following.

In the explanations, I limit myself to the essential contents of the official set of rules. There are still one or the other subtlety, but it doesn't play a significant role for getting started and participating in F3G. In my opinion, the best thing to do is to participate directly in an F3G competition or to watch and talk to the pilots.

When F3G was initiated the objective was to adopt and supplement the very successful international class F3B. The established and proven F3B regulations had to be adapted to the use of a standardized, modern electric drive.

Readers experienced in F3B will recognize the very close relationship between the two classes.

The core of F3G is three different, very different flight tasks with one and the same model

• Duration - flight of 10 minutes with precision landing

• Distance - flight:within 4 minutes as often as possible through a 150-meter route

• Speed -  pass a 150-meter route 4 times as quickly as possible

as optimally as possible in comparison to the competitors.

Both the model and the pilot are required to have very good all-round characteristics in order to achieve top performance in all three tasks.

A  F3G round always consists of a complete sequence of time, distance and speed flights. The individual tasks are carried out as independent flights with take-off and landing.

Normally depending on the weather, 3 laps are flown, so that each pilot has at least 9 flights - 3 x speed, 3 x distance, 3 x duration.

The pilot must use the same model within a round. For this purpose, the model or other replacement models will be marked before the competition to ensure that no parts are exchanged during a round.

Definition "model"

A model consists of fuselage, wings, elevator/rudder, connector, canopy and 3 sets of batteries. Damaged propellers and spinners may be replaced between tasks.

If a model is damaged during a task, the pilot must repair it in order to fly the remaining tasks of the round.

Switching to another (backup) model is only allowed

• • Between rounds

  • Within a round if the model has been damaged by another pilot/model, e.g. mid-air collision.

Which changes may then be made to the model between the tasks. The rules are clear here.

The pilot may change the weight of the model between tasks. In practice, ballast is loaded for distance and speed.

In addition, only changes to the model that can be made via the remote control are permitted. Usually this is the adjustment of the flaps on the wing and the trim.

Telemetry

As in many other classes, telemetry is not allowed. Only the transmission of the voltage of the receiver power supply and reception quality is permitted.

The use of "gyros" or other devices that intervene directly in the flight without the pilot being involved is also not permitted.

Working- and Task-Time

If it is already challenging to master three very different tasks with the same model, the F3G regulations (as already proven with F3B) offer a tactical spice for the pilots and their helpers with the working- and task-time.

Each task has a defined task-time in which the task should be flown

Duration = working time 12 minutes

Distance = working time  7 minutes

Speed = working time 4 minutes

The working time is started by the organizer and its start and end are signaled acoustically.

The task time is the time frame in which the flight task is evaluated. These are

Duration = 10 minutes

Distance = 4 minutes

There is no task-time for speed. It begins with the entry at the base-A of the track and must be completed no later than 4 minutes after the start of the working time with the exit at base-A again, otherwise there will be no score.

For distance and duration, the pilot may make any number of attempts within the working time.

Only performances that are flown within the working time  will be counted.

In the following graphic I have visualized the connection as an example for a cross-country flight. 

• • • The organizer starts the frame time of 7 minutes

    • The pilot starts and starts his task time of 4 minutes with the entry into the track at base-A

    • After some time he decides to stop the attempt and start again. That's why he lands.

    • There is a new start within the working time.

    • The new working time of 4 minutes for the pilot begins with the renewed crossing of base-A.

    • The 7 minute working time ends before the pilot has “used up” his 4 minute task time and before the pilot has landed.

    • Only the completely flown 150 meter distances are counted until the end of the frame time.

This all sounds more complicated than it really is. The combination of working time and task time offers very exciting and interesting tactical options and decisions for the pilot.

Partial Scores

The evaluation of a pilot's performance in duration and distance is always based on the group of pilots who flew the task with him at the same time.

This scoring also reduces the influence of the weather since all pilots in a group can and must fly within the same time window (working time).

A distance group usually consists of 4-5 pilots. In duration, up to 10 pilots can fly at the same time.

The performance of the pilots within a group are normalized to 1000 points so that they can be compared between the groups.

Let's take two XC groups as an example. 

• • In the first group, the best pilot flies 20 laps and receives 1000 points.

  • In the second group, the maximum number of laps is 11 and Pilot-G and Pilot-H receive the maximum 1000 points with 11 routes. The other pilots within the respective group receive a lower percentage of points, depending on the routes they have flown.

The composition of the groups will be changed between the rounds so that different pilots within a group have to compete against each other.

The F3G task duration shows the greatest deviations from F3B and leans heavily on F5J to make it exciting.

The goal is to fly as accurately as possible for 10 minutes (600 seconds) and complete the flight with a precise landing at an assigned landing spot.

The flight time starts when the motor is switched on and ends when the model comes to a standstill. So-called “push-in landings” are theoretically allowed. Given the probable damage and cost of broken propellers, spinners and possibly motors, no pilot is likely to risk a push-in landing at F3G.

Each second of flight time is worth one point. If the 600 seconds are exceeded, one point per second will be deducted.

Depending on the distance to the landing point, points are awarded for the target

The so-called F5J altitude is subtracted from the points for the flight time and landing. Up to 250 meters, 0.5 points will be deducted for each meter in altitude. From 250 meters on there are 3 points per meter of altitude.

The starting height is the maximum height that the model has reached with the motor and 10 seconds after switching off the motor.

Perhaps the 10-second rule after switching off the engine is surprising. This prevents the pilot from accelerating the model at a low altitude and the speed being converted to altitude after the motor has been switched off.

In practice, no pilot will deliberately climb over 250 meters, since the penalty is too high.

The pilot, with the help of his helpers, has to estimate the height he wants to climb with the help of the electric motor to allow the 10 minutes duration to be completed.

If the climb is terminated at a low altitude, there is a smaller F5J height penalty, but there is a higher risk that the model has to land early, which in turn means a lower score.

If the model climbs too high, the 10 minutes can probably be flown without any problems, but there will be a higher F5J height deduction due to the higher take-off altitude.

The start height is documented and displayed via the logger. It is not allowed to use the logger to automatically switch off the motor at a certain altitude.

The working time for the duration is 12 minutes.

Within the working time, the pilot can undertake as many starts as he likes. The logger must be reset before starting again. Only the last attempt counts.

The F3G task distance is very closely based on F3B. the goal is to fly as many 150 meter laps as possible within the task time of 4 minutes.

Additional rules were introduced for F3G to take into account the nature of the electric motor and climb.

The entry and thus the start of distance may only take place 40 seconds after the start of the motor to prevent the model from being accelerated with the motor before entry.

300 penalty points are applied if the entry happens earlier (<40 seconds).

Practically,  the helper stops the time and provides feedback to the pilot when the entry may take place, or as an alternative a voice counter/stopwatch is used in the transmitter which announces the time.

In order to achieve the best possible glide ratio of the model, the weight is increased for distance using ballast. Since the increased weight reduces the climb performance with the motor, the pilot has to weigh up how much weight and thus wing loading is optimal for the current weather conditions.

The working time for distance  is 7 minutes.

The task time of 4 minutes begins with crossing base-A in direction to base-B.

Any number of attempts are possible within the frame time. That means the pilot can land at any time, reset the logger and try again.

Only the last attempt is counted.

Only completely flown laps are counted.

At distance at least 3 pilots, in practice 4-5 pilots, fly at the time against each other.

Crossing base-A or base-B is indicated optically (lamps) or sometimes also acoustically. 

It therefore makes sense to use 2 helpers as a pilot. One of the helpers indicates the remaining task time and reports that the bases have been crossed. The 2nd helper supports the correct tactical assessment and observes the other pilots in the air.

The task Speed of F3G is also closely aligned with speed at F3B. The aim is to fly 4-times a 150 meter lap as quickly as possible. The time is measured from entry at base-A in the direction of base-B until the exit at base-A again.

The working time for the Speed is 4 minutes. There is no task time. The attempt begins with the crossing of base-A in the direction of base-B. A restart is only permitted as long as the entry has not yet taken place.

As with Distance, the entry and thus the start of the task Speed may only take place 40 seconds after the start of the electric motor. This is intended to prevent the model from being accelerated with the motor before entry. 

300 penalty points are applied if the entry is earlier (<40 seconds)

In this task, each pilot flies alone. Therefore there is no group-related scoring. The points (1000) are awarded as a percentage based on the fastest pilot.

Crossing base-A or base-B is indicated acoustically. 

In order to maintain speed as good as possible over the 4 laps, the weight of the model is usually increased using ballast. Since the increased weight reduces the climb performance with the motor, the pilot has to decide how much weight is optimal for the current weather conditions.

With regard to the models that can be used, the F3G rules only specify a few parameters. These are:

• • Minimum wingspan: 2800mm

  • Minimum wing loading: 35gr/dm2 

  • Maximum wing loading: 75gr/dm2

  • Maximum flying weight: 5000 gr.

The calculation of the wing area refers to the total projected area of ​​wing and tail.

The radius of the tip of the fuselage, in F3G of the spinner, must not be at least 7.5 mm. This does not refer to the diameter of the spinner but to the spinner tip.

The few parameters open up a wide field in terms of the models that can be used in compliance with F3G.

Today F3B models equipped with a special electric fuselage are used. Since the F3G set of rules is very close to F3B, their design fits very well for F3G too.

The dimensions of the current models roughly result in a minimum weight of around 2,200 grams at 35 g/dm2. This means that the normal and proven material designs and wing structures can be for F3G. 

A special lightweight design is not necessary and makes no sense, as otherwise ballast has to be added to comply with the  minimum wing loading.

The following list provides an overview of possible F3G models as they have already been used in F3G competitions. It does not claim to be complete.

Device - Weberschock

Shinto Pro - Aer-o-tec

Pike Precision 1.2 - Samba

Avatar - JITOM

Crossfire - Aer-o-tec

Freestylers - TUD

Jedi lift - Baudis

Fosa - Baudis

 Matrix - Modellsport Hugler

Incidentally, there are also special fuselages or "noses" for an electric motor for many "older" but no less performant F3B models. It is worth contacting the manufacturer and asking.

When installing the components in the electric fuselage, the following arrangement has proven itself and is widely accepted.

• • • The servos and receiver are housed on a board in the rear, behind the connector. It is attached using small screws from below or from the side via the molded profile on the fuselage.

    • The tail unit is connected using CFK tubes. These no longer have to be specially supported because the short length to the tail and the fuselage cross-section limits sagging.

    • The battery is In front of the connector and can be changed via a canopy.

    • Controller, logger and current sensor are connected to the motor, partially soldered, forming a compact unit which is screwed to the nose of the fuselage.

All electric fuselages have in common that they are very compact and narrow for aerodynamic reasons.

Therefore, when selecting the motor or battery, care should be taken to ensure that it fits into the fuselage cross-section and can be changed quickly via the canopy. 

This requirement has led to a trend towards smaller LiPo batteries (800-1000 mAh) with a higher number of cells (5+S) in 2021. These can simply be better accommodated in the fuselage and exchanged between flights.

Due to space limitations and to save weight in front of the center of gravity, attention should be paid to “cable management” and all cables should be shortened where possible.

When using "heavy" drives, it may be necessary to install weight in the rear/tail in order to achieve the desired center of gravity.

Der Logger/Limiter spielt eine wichtige Rolle in F3G. Für Piloten, welche nicht bereits Erfahrung mit einem Logger/Limiter in einer anderen Klasse wie F5J oder F5B gemacht haben, ist die Funktion erst einmal ungewohnt.

Deshalb möchte ich, bevor ich auf die F3G Regeln bzgl. dem Logger/Limiter eingehe, die generelle Funktionsweise beschreiben.

Funktion

Der Begriff Logger / Limiter bezeichnet zunächst einmal die unterschiedliche Funktionsweise des “Gerätes”. Wobei beide Funktionen in ein und demselben “Gerät” enthalten und konfiguriert werden können.

Als Logger verhält sich das “Gerät” passiv. D.h. es zeichnet nur spezifische Daten auf greift aber nicht in die Kontrolle des Reglers und damit Motors ein. Ein Beispiel ist die Messung der F5J Höhe im F3G Zeitflug. Der Logger protokolliert dabei nur die währen des Steigfluges und 10 Sekunden nach Abschalten des Motors maximal erreichte Höhe, da diese in die Wertung des Zeitfluges eingeht.

Als Limiter ist das “Gerät” aktiv. D.h. es greift in die Steuerung des Reglers und Motors aktiv beim Erreichen eines konfigurierten Limits ein. Beispiel hierfür wäre in F3G die maximal 30 Sekunden Motorlaufzeit. Wenn diese konfiguriert sind, schaltet der Limiter 30 Sekunden nachdem der Sender/Empfänger den Motor eingeschaltet hat, diesen aus. Der Sender kann immer noch auf “Motor-An” stehen, aber das Signal wird vom Limiter nicht mehr an den Regler weitergegeben sondern übermittelt an den Regler “Motor-Aus”.

Dadurch muss sich der Pilot/Helfer nicht um die maximale Motorlaufzeit bzw. Energie (350Wmin) kümmern. Der Limiter - wenn er so konfiguriert ist - schaltet automatisch den Antrieb beim Erreichen dieser Grenzwerte aus.

Der Limiter kontrolliert auch, das der Motor nur einmal eingeschaltet werden kann und verhindert aktiv ein erneutes - gewolltes oder ungewolltes - Einschalten des Motors. Das kann am Anfang etwas ungewohnt sein, wenn man im Training evtl. noch einmal mit dem Motor steigen will, dieser aber nicht mehr angeht.

Dies erfordert, das für einen Restart der Logger Zurückgesetzt werden muss. D.h. das nach der Landung der Logger kurz vom Akku getrennt oder soweit vorhanden über einen Reset-Schalter zurückgesetzt wird.

Theoretisch und praktisch kann es vorkommen, das der Sender noch auf “Motor-An” steht der Logger diesen aber abgeschaltet (30 Sekunden) hat und der Pilot zum Restart landet. Um zu verhindern das beim Zurücksetzen des Loggers der Motor ungewollt direkt anläuft erlauben die Logger ein Zurücksetzen nur wenn auch am Sender der Motor auf “Aus” steht.

Ich persönlich habe mir angewöhnt ganz bewusst den Motor am Sender auf “Aus” zu schalten auch wenn dieser vom Logger abgeschaltet wurde.

Im folgenden verwende ich nur noch den Begriff Logger und beschreibe damit das Gerät an sich und nicht dessen Funktion.

Anforderungen F3G FAI Reglement

Bezüglich dem Logger sind im FAI F3G Reglement sehr viele und detaillierte Anforderungen definiert. Die wesentlich sind dabei:

• Der Logger muss den Motor nach spätestens 30 +0,1 Sekunden nach dem Einschalten des Motors automatisch Abschalten, falls der Pilot dies nicht bereits vor Ablauf der Zeit manuell vornimmt.

• Der Logger muss den Motor bei Erreichen der Energiegrenze von 350 +1 Wmin automatisch Abschalten.

• Der Logger muss die während dem Steigflug mit Motor und 10 Sekunden nach (automatisch oder manuellen) Abschalten maximal erreichte Höhe speichern.

• Er muss verhindern, das der Motor öfter als einmal gestartet werden kann.

• Er muss mindestens alle 0,1 Sekunden die aktuellen Werte für Höhe, Spannung, Strom, akkumulierte Energie und Motorlaufzeit protokollieren.

• Verboten ist den Logger so zu konfigurieren das die Abschaltung bei einer bestimmten Höhe erfolgt.

• Nach der Landung muss es für den Veranstalter möglich sein über eine integrierte oder einfach anzubringende Anzeige die wettbewerbsrelevanten Werte - Energie, Motorlaufzeit, F5J Höhe - abzulesen ohne das der Logger vom Empfänger getrennt oder aus dem Modell ausgebaut werden muss.

Daneben sind noch 2 Anforderungen welche ich direkt kommentieren möchte.

Der Logger (Stromsensor des Loggers) muss auf der Plus-Seite zur Batterie einen 4mm Stecker besitzen. An dem Plus Anschluss zum Regler muss eine 4mm Buchse verwendet werden.

Da jeder Pilot sein eigenes Stecker-System verwendet reicht es entsprechende Adapter auf das geforderte Stecker-Buchsen System zu haben, damit im Bedarfsfall eine Überprüfung des Loggers durch den Veranstalter möglich ist.

Der Logger muss von der EDIC der FAI geprüft und freigegeben sein.

Die aktuelle eingesetzen Logger der Firmen Aerobtec (Altis V4+) und SM-Modellbau (Unilog2) besitzen eine Zulassung der EDIC für F5J. Für F3G ist die Zulassung für den Aerobtec Altis V4+ in Arbeit.

Der Veranstalter kann über eine sogenannte “local rule” Logger für den Wettbewerb zulassen obwohl diese noch nicht vollständig durch die EDIC überprüft sind.

Konfiguration des Loggers

Die Konfiguration des Loggers erfolgt in der Regel über eine graphische Oberfläche einmalig am PC. Der Aerobtec Altis V4+ und SM-Unilog2 können auch über ein externes “Eingabe-Terminal” konfiguriert werden, wobei dies über den PC meist deutlich einfacher und benutzerfreundlicher ist.

Einige Hersteller haben bereits eine vordefinierte Konfiguration für F3G als einfache Menüoption, womit alle für F3G relevanten Parameter so eingestellt werden dass diese für F3G und den Wettbewerbseinsatz passen.

Einmal eingestellt und konfiguriert benötigt der Logger keine weitere, besondere Beachtung oder Pflege.

Einbau des Loggers

Damit der Logger die vom F3G Reglement geforderte Funktion und Kontrolle ausführen kann ist ein bestimmter Einbau und Integration in den Antriebsstrang erforderlich.

Der eigentliche Logger sitzt zwischen Empfänger und Regler. Das Empfänger Ausgangssignal geht in den Logger. Der Regler ist mit dem Ausgangssignal des Loggers verbunden. Dadurch kann der Logger den Regler unabhängig vom Empfänger steuern und z.B. beim Erreichen des maximalen Motorlaufzeit von 30 Sekunden unabhängig vom Empfängersignal abschalten.

Zur Messung von Spannung, Strom und damit verbunden Leistung und Energie wird ein sogenannter Stromsensor als Ergänzung zum Logger benötigt. Dieser ist herstellerspezifisch.

Der Sensor sitzt in der Plusleitung zwischen Akku und Regler. Über ein meist dünnes zusätzliches Kabel am Sensor wird über die Minus-Leitung zwischen Akku und Regler die aktuelle Spannung gemessen.

Zur Übermittlung der Messwerte vom Stromsensor wird dieser über ein herstellerspezifisches Kabel mit dem Logger verbunden.

Abschließend lässt sich sagen, das der Umgang mit dem Logger anfänglich etwas ungewohnt aber nicht kompliziert ist. Einmal konfiguriert verrichtet er seinen Dienst.