Marymoor RC Club
Special Protocol and Rules for Outside Educational Institutions to Fly at Marymoor RC Airfield
DRAFT May 10, 2021
We have found that students and faculty from institutions such as the Aviation High School or the University of Washington who have used our airfield for their projects in the past have been highly professional and strong technically. However, they are often not as familiar with many practical aspects of the RC hobby and rapidly changing technology of the hobby. Therefore, the Board of Directors for the Club has adopted the following additional rules and protocols for such groups.
- A team of MAR/C members shall be appointed to review the design and installation of equipment according to the criteria below.
- The MARC team and the outside organization shall conduct inspections according to the checklists to be developed under the Flight Operations section of this document.
Design of the Aircraft
- The aircraft must have a wing loading of no more than 35 oz. of gross flying weight per square foot of wing area. For canard or tandem wing configurations, the wing loading of the highest loaded wing must be 35 oz/square foot or less. The measurement is made at the highest gross weight expected.
- The aircraft must have a gross flying weight of 25 lbs. or less.
- The center of gravity of the airplane must be measured, and must be at least 10% of mean aerodynamic chord forward of the center of lift.
- Tail surfaces and tail length must be sufficient for stable flight. The vertical fin size must be large enough to avoid high adverse yaw.
- Servos must be installed and operating to control all three axes
Equipment and Installation
- All radio equipment shall be recently purchased and shall be of main-stream brands such as Spektrum, Futaba, Hitec, or Savox. Teams are cautioned never to build aircraft from the least expensive equipment to be found on the internet.
- Any open architecture systems must be shown to have all available updates. The transmission and reception protocols shall not be changed.
- Servos must have metal gears and be shown to have sufficient torque to operate in worst case hinge moment conditions at the minimum voltage expected.
- In the ready-to-fly configuration with batteries installed, a thorough range check procedure shall be followed based on the recommendations in the manual for the transmitter and receiver. In addition to such procedure, the test must pass with the airplane nose pointed to the transmitter, sides, and tail. Then the aircraft must be placed on it’s nose and the test passed as it is rotated though 360 degrees of roll.
- Multiple receiver antennas must be used, and must be place at least 8 inches apart and oriented 90 degrees to each other. At least two antennae must be used. 3 or more are highly recommended if the system allows. Extreme caution must be exercised to ensure that the antennae are not blocked by conducting elements of the aircraft such as batteries, engines, metal wing tubes, or any carbon structure.
- The transmitter and receiver must have a “fail safe” feature and it must be used so that any loss of signal will cause the throttle to go to zero in the case of electrically powered aircraft, or to idle for internal combustion engines. The operation of the fail safe feature must be demonstrated before each flight.
- If the aircraft weight is over 10 lbs., a dedicated battery shall be used to power the receiver and servos, or if the battery eliminator circuit (BEC) of the electronic speed control (ESC) is used to power the receiver and servos, a battery backup system such as an Opti-Power Ultra Guard may be used to ensure that any fault in the ESC or BEC shall not cause loss of power to the radio gear. Two dedicated batteries in parallel with a battery share system are strongly recommended. In any case, the total battery capacity available to receiver and servos must be at least 5 times the expected amp-hours consumed in a single flight.
- The aircraft structure must be shown to be sufficiently sound to withstand normal and aerobatic flight loads.
- All participants shall follow the AMA safety code and the MAR/C rules.
- Comprehensive pre-flight inspection by the MAR/C team shall be conducted before each flight. A robust range check and verification of correct operation of the fail safe feature shall be done before the first flight of the day, or after any changes are made to the positions of any antennae or conductive items in or on the aircraft.
- Three checklists shall be developed by the organization for their aircraft, and used at appropriate times by the organization and Marymoor RC Club inspectors or pilots:
- First Flight Inspection Checklist (example in the appendix) used prior to the first flight of the aircraft, or prior to any flight following modifications.
- Preflight checklist, conducted each time the aircraft is assembled at the field and powered up for the first flighty of the day.
- Before Takeoff checklist, accomplished prior to takeoff of every flight, with the aircraft powered. An example is B A T T C:
- Battery charge (of the transmitter)
- Antenna (of the transmitter positioned correctly)
- Trims (set)
- Timer (set to time the flight to avoid running out of power or fuel)
- Controls (all controls have full throw and move in the correct direction)
- The flight area using either GPS or visual landmarks shall be specified prior to each flight, and shall be conservatively within the normal flight boundaries at the MAR/C airfield, according to the risks associated with that flight. For example, the first few flights must take place well within the boundaries.
- A MAR/C pilot shall accompany and advise the pilot, and assist in maintaining the aircraft within boundaries.
- Agreement shall be made prior to each flight of the conditions that would require the pilot to sacrifice the aircraft to prevent it from going outside the flight boundaries. The method to sacrifice the aircraft will also be agreed, and must be such as to minimize the energy of the airplane at ground contact.
- Aerobatics are prohibited unless required by the mission.
- If the aircraft is to have payload or operate at various weights, initial flights will be at the lightest configuration and weight will be gradually increased in subsequent flights.
- A power-off and partial power stall shall be demonstrated at a safe altitude each time the weight of the aircraft is increased. If the aircraft has high-lift devices such as flaps or slats, or spoilers or speed brakes, the stall shall be demonstrated in all configurations.
- All batteries shall be fully charged at the beginning of each flight. A battery charger may be brought to the field where power is available.
- The pilot(s) shall have current full membership in the AMA. Park pilot or temporary trial memberships are not sufficient.
- The pilot(s) shall be full and current members of MAR/C, and shall have passed the proficiency test.
- The pilot(s) shall have had experience flying aircraft in the weight class and wing loading of the aircraft being flown for the project.
Before First Flight Inspection Checklist
(EXAMPLE ONLY -- for a simple trainer airplane)
Pilot (or Student) Name_______________________
Description_____________________ Power: Nitro____ Electric____ Glider____
Radio Brand__________ Freq: 2.4GHz_____ 72MHz____Channel____
- Aircraft power is OFF
- Check radio battery: 4c/5volts, 5c/6volts.
- Engine / Motor are secure in mount.
- Muffler, accessories, prop are secure and installed correctly.
- Check prop for damage.
- Was prop balanced prior to installing?
- Check nose wheel installation for security. (if installed)
- For nitro power check firewall and nose area for fuel proofing.
- For nitro power check fuel tank installation, tank security, secure fill and feed line’s:
- If cowl is used check for secure installation.
- Are servos mounted correctly, rubber mount, grommet flange against mounting surface.
- Check that wires are routed to preclude hang up on servo arm motion.
- Are all mounting screws tight? Is control arm screw tight?
- Check that control rods are secure with supports to prevent flexing.
- Attachment of control rods to servo is secure and non binding.
- Receiver is secured and isolated from vibration.
- Check that receiver antennas are installed correctly.
- Check that battery is secured and is isolated from vibration.
- For electric need to verify that battery is not damaged/puffed, that hold down is adequate to prevent movement in flight, and correct connection to motor/ESC.
- Check that all clevises have “safety” tubing to prevent opening in flight.
- Check fin and stabilizer for solid mounting.
- Pull test fin to rudder hinges and stabilizer to elevator hinges.
- Check rudder and elevator control horn and clevises for secure mounting.
- If required check tail wheel for secure mounting and non-binding steering.
1. Check for damage, warps, center section reinforcement and/or wing joiner for two piece wing.
- Pull test aileron hinges, check control linkage , control horn security and clevises.
- Check wing mounting for secure attachment hold down; dowels or bolt hold down.
- Before installing WING, insure required AMA identification data is applied. (Gen rule 6)
- Install Wing: prefer nylon bolts or minimum of 10 new rubber bands.
- Visually check overall alignment of wing, fin, and stabilizer.
- Check CG; fuel tank empty, use main SPAR if location is unknown. Correct as required. 2. Insure battery is installed when checking CG for electrics. 3. Note: For low wing aircraft , turn model over to check CG. 4. If possible check lateral balance.
POWER ON CHECKS:
- If the aircraft is electric powered , tie down and insure that throttle stick is in idle position.
- Turn on transmitter: check battery is 10 volts min. (Maybe lower voltage on some 2.4)
- Check that control surfaces move in correct direction and throttle idle to full is correct.
- Check that control throw is sufficient for flight.
- Check that the control surface is trimmed to the primary flight surface.
- Perform a range check according to the instructions for the receiver and transmitter used (they are all different), AND perform the check with the airplane in several orientations.
- Test the Fail Safe function of the radio by restraining the airplane, setting the throttle above idle so that the prop is spinning, then shutting off power to the transmitter. The motor should go to zero power after several seconds.
- Range check for Spektrum: enter range mode (press and hold bind button) @ 90 ft.
- TIE DOWN AIRCRAFT PRIOR TO ANY ENGINE or MOTOR OPERATION/ADJUSTMENT.
- Start engine, perform power test/idle test, LOW trim shut off.
- For electrics check whether ESC is set to “hard brake” or “free- wheeling”.
- If required, set up “buddy box” to insure compatibility with primary transmitter.
- If required and if available perform 90db test.