Once you've learned the basics, you're ready to get into the finer details of competitive speed flying.
COURSE AND FLIGHT RULES
Spotter - All pilots shall have a spotter or caller that stands with them during their flight as a means to provide feedback to the pilot regarding flight path, course boundaries, safety, and identification of full-scale aircraft in the immediate vicinity. If a pilot does not have a spotter at the time of flight, then an event official shall perform this role instead.
Number of Scoring Rounds - A flight from which an official score is measured is referred to as a round. A minimum of one round per class shall be executed for all pilots.
Course Length - Course length shall be determined by blade size. Classes 1 and 2 shall run on the short course and Classes 3 through 6 shall run on the long course. See the Course Layout section for details of course geometry.
Pre-Staging - All pilots whose skill level is identified as master shall run a course that is bounded on either side by a pre-stage. The intent of this is for the pilot to control the model’s entry into the pre-stage area so that it is in level flight such that the resulting course speed is not significantly enhanced by diving. The pre-stage length shall be one-half of the length of the course to which it is applied. Novice pilots are not required to observe a course pre-stage. See the Course Layout section for details of course geometry.
Flight Path - The model shall travel the base course in both directions without landing. All models shall be in level flight at the point of entry to the pre-stage and course. The flight path shall be parallel to the base course and shall not cross the course boundary.
Flight Altitude -The altitude of the model shall remain below 35 meters (114.8 feet) and above 5 meters (16.4 feet) during the flight through the course and/or pre-stage depending on the event type. Altitudes are measured from the pilot’s base. An altitude infraction will result in a null pass.
Line-of-Sight Control - Only control of the model via direct visual contact is allowed. First-Person Video control is not permitted.
Flight Time Limit - The pilot has 3.5 minutes from lift-off to complete as many passes as possible and shall land before the time runs out. In the event that this limit is exceeded, the pilot’s flight will be considered null for purposes of formal scoring or ranking.
Demonstration Flights - Manufacturer model and hardware demonstrations may be performed and scored at the discretion of the contest director, but shall not count towards formal records, rankings, or circuit standings.
MODEL ENTRY RULES
Number of Entries - A pilot can compete with one entry per class. The limit on the number of classes in which the pilot may participate is left to the discretion of the contest director. A pilot is permitted to fly up to two additional entries not of their own; however, any records, rankings, or circuit standings are awarded to the model owner.
Homologation Rule - Models of the Sport body type shall be commercially available and have a minimum of 30 kits available to the public no later than 30 days before the event date.
Model Configuration Rules
Maximum Weight - The maximum ready-to-fly weight of a given model must not exceed the value listed below for its respective blade size range:
Class 1 - 200-400mm: 1750g
Class 2 - 401-530mm: 3750g
Class 3 - 531-630mm: 5500g
Class 4 - 631-720mm: 6750g
Class 5 - 721-780mm: 7500g
Class 6 - 781-850mm: 8000g
Auxiliary Propulsion - Models shall be propelled by the main rotor only and may not include compound propulsion (e.g. tractor/pusher propellers, rockets, etc).
Auxiliary Airfoils - Models shall not have wings or other auxiliary airfoils with a surface area more than 4% of the main rotor swept area.
Power Systems - Electric, nitro, and gasoline power systems may be used in any model classification. The power system no-load voltage, glow displacement, and gasoline displacement limits shall be 72V, 23cc (1.4 cubic inches), and 40cc (2.3 cubic inches).
Retractable Landing Gear - Retractable landing gear may be used on any model as long as they can be shown to be stable during the technical and safety inspection.
Rotor Blade Composition - No metal blades are allowed. Only commercially-available blades are allowed for those models of the Sport body type that are classified as Stock. Formula models and models of the Sport body type that are classified as Modified may use experimental composite blades; however, these blades shall be approved by the contest director a minimum of 30 days prior to the event date.
Tail Rotor Protection - All models shall have a form of landing gear and tail skid sufficient to protect the tail blades from ground strikes.
Modifications - Modifications from stock configuration may be performed on all models; however, a model shall not be allowed to fly if a modification is deemed to be a safety hazard during the technical and safety inspection.
FLIGHT SAFETY RULES
Personnel Protection - Pilots and spotters shall wear an approved helmet at all times when beyond the designated safety line to compete, practice, or test during the event. Helmets shall carry a DOT, ANSI, OSHA, Snell or equivalent safety rating.
Model Flight Safety - The pilot shall maintain control of the model throughout the flight. If the model exhibits signs of high speed instability, erratic flight, a stall, or an in-flight anomaly, the pilot will be asked to land as soon and as safely possible. Any 3D maneuvers, aerobatics, or “showboating” will not be tolerated and will result in the pilot being asked to land and that flight being considered null for purposes of formal scoring or ranking.
Inspections - All models shall undergo a technical and safety inspection before entering the event. If the officials call for a flight termination due to a model flight safety violation, then a re-inspection of the model shall be performed before it can resume competition. Officials shall identify any and all conditions that represent a constraint to flight and request that they be corrected before the model is declared competition ready. At any point during the event, an official may call for a random inspection, to which the selected pilot shall submit. If this inspection is refused, then the selected pilot shall be disqualified from further participation and will lose all official scores and rankings for the event.
MODEL TIMING AND SPEED COMPUTATION
Methods - Timing of a pilot during a flight shall be accomplished by way of using a single timing device such as a chronometer with two triggers or two timing devices that are used independently to determine two sets of times. If two devices are used, then the two times measured per run shall be recorded separately and the average of the two measurements shall be computed in order to determine the official time for a given run.
The elapsed time of the model through the course is measured by starting and stopping the timer by the timekeepers at the entry gates as indicated by visual confirmation that the model has crossed over the course boundary into and out of the course. Each timekeeper should sit at their course timing station and align their sight lines with the two pylons that represent the course boundary as a means to determine when the model has crossed the boundary.
In practical terms, this is accomplished via one of two ways:
Method 1: Direct actuation of a timing trigger by a trigger judge at either of the two course timing stations in the case where a single chronometer-style system is used.
Method 2: Direct actuation of a stopwatch by one of two timekeepers at the scoring station upon perception of a trigger event that results from one of the two trigger judges at the timing stations performing a trigger action. The trigger actions are most typically waving a flag or flashing a light when the model is perceived to have crossed the course boundary.
Timing Devices - Time measurement shall be accomplished by timing devices approved by MHSFA. If electronic stopwatches are used, timekeeping must be performed simultaneously by two timekeepers utilizing devices capable of indicating time to at least 1/100 of a second (10 milliseconds). Automated and other electronic timing devices which register a single time are allowed provided the system is approved by MHSFA.
Timing Uncertainty - While there are multiple sources of error in any giving timekeeping system, for those methods that use a human in the loop (non-automated timing systems), the largest source is the timekeepers’ reaction times to the visual/auditory stimulus of a trigger event. Typical human response times to anticipated visual and auditory stimuli can be up to 0.25 seconds (250 milliseconds).
The effect of this response time on the resulting uncertainty included in the recorded time and computed speed is inversely proportional to the elapsed time in the course. In other words, as a model’s elapsed time in the course decreases (speed increases), the uncertainty has a proportionally larger effect on the recorded time value and computed speed. A reasonable expectation for the magnitude of relative uncertainty in computed speed for non-automated timing systems is 5-20% depending on the specific means by which the trigger events are being assessed.
Even though this is considered a random error, the measurement uncertainty resulting from this can be minimized by ensuring consistency in timekeepers and/or trigger judges. The timekeepers and/or trigger judges should not be relocated or changed during the event, as this will introduce different error magnitudes that were not present during previously-timed rounds. While humans in the loop will always add uncertainty to the final times and computed speeds, with a consistent timekeeping team, the uncertainty is incurred as a fixed bias rather than a truly random error.
Thus, maintaining a consistent timekeeping team allows us to consider the uncertainty incurred by human reaction times as a systematic error because a person will tend to react consistently to the same stimulus. For example, if the left trigger judge always reacts too soon and clicks the trigger before the model crosses the course boundary and the right trigger judge always reacts too late and clicks the trigger after the model crosses the course boundary, then the following can be inferred:
All left pass times will be higher than reality (slower speeds).
All right pass time will be lower than reality (faster speeds).
All left and right passes will be timed consistently and have a fixed bias or systematic error from reality that is represented by the sum of the trigger judges’ individual reaction times in combination with the timing instrument accuracy.
While non-automated time measurements and computed speeds will always suffer from inclusion of human reaction time errors, utilizing a consistent timekeeping team during an event will ensure that the precision (repeatability or reproducibility) of the measurements is maximized even in absence of high accuracy (proximity to the true value). This high precision is the key characteristic that any timekeeping method must have if results are to be compared for the purpose of ranking.
Recording - Recording of times for each pilot shall be performed either electronically or on paper. All runs for each pilot shall have a time assigned to them with the only exception being when a run is called as null by the contest director. Each time shall be recorded to a minimum of 1/100 of a second (10 milliseconds) precision.
Computing Speed - Once times are recorded for each pilot, the scorekeeper shall, as a minimum, identify the best left and the best right time for each pilot for use in computing the speeds. To compute the official average speed for each pilot, the following equation shall be used, where course length is in meters and time is in seconds:
Average Speed = 7.2 * Course Length / (Best Left Time + Best Right Time) in kilometers/hour
Average Speed = 4.471 * Course Length / (Best Left Time + Best Right Time) in miles/hour
Final Scoring Report - Upon completion of computing all pilots’ official average speeds, the contest director shall provide a copy of this documentation to MHSFA for use in maintaining attendance and pilot performance records.