Introduction to EDF Electric Ducted Fan Model Flying

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					  Introduction to EDF
(Electric Ducted Fan)
         Model Flying
             Jim Shima
           AAM Meeting
               1/4/2011
Apropos to RC Model Flying
“Aviation in itself is not inherently dangerous.
  But to an even greater degree than the sea, it
  is terribly unforgiving of any carelessness,
  incapacity, or neglect.”
     — Captain A. G. Lamplugh, British Aviation Ins Group, c. early 1930's.


“There are two critical points in every aerial
  flight - its beginning and its end.”
     — Alexander Graham Bell, 1906.
EDF Overview
   With the advance of battery technology and brushless
    motors, EDF offerings have exploded and gained
    popularity in the past 3-4 yrs.
   Foam molding has allowed almost any plane/military jet
    in EDF form to come to market.
   Larger 15+ lb. fiberglass/composite EDFs have also
    gained traction in the hobby – even rivaling turbine
    performance (BVM/Tamjets).
   Li-Po battery technology allows for larger planes and
    more powerful fan units (sourcing several hp).
   EDF units vary from 50mm small fans to over 120mm.
    Some sizes are “standard”, but there are also
    manufacture specific sizes.
EDF Basics
   Brushless motors used due to their
    high efficiency.
   Motors are rated with “KV” spec.
    This denotes the motors unloaded
    RPM per volt. Ex: 4000KV is 4000
    RPM/volt. With 10V going to the
    motor, the RPM would be 40,000.
   EDFs max out around 50-65k RPM.
    Must scale the motor and battery to
    match the EDF unit. More blades ->
    lower KV motor, less blades->higher
    KV motor.
   Static thrust is governed by fan
    diameter, motor RPM, number of fan
    blades.
   Stators on the back of the EDF
    housing straighten out airflow.
   Inlet lip/flange has great effect on
    static thrust – keep ducting and inlet
    smooth!
Typical EDF Setup
   Fan unit (rotor, housing, collar,
    rotor plug)
   Brushless motor (size/KV
    depends on fan diameter)
   Brushless ESC - max amperage
    depends on fan size+motor (30-
    100A)
   Battery pack size (2s-12s lipo)
    and capacity (1300-10,000mAh)
    depending on above
   Optional BEC (most ESCs have
    built in BEC circuit, 2-3A)
   Thrust tube
   Any 5 to 9 channel RC radio and
    Rx (2.4G preferred but not
    necessary)
Flying an EDF/Turbine Model
   Anyone can fly one if you abide by simple rules
       On takeoff/launch let the model get “on step” before giving
        it large control surface input.
       Thrust is not immediate, think 2 sec ahead.
       Make wider turns, remember you don’t have a prop
        pushing air over the wings.
       Military jet models have higher-wing loadings and stall
        easier – don’t expect to glide it in.
       Land with some power! Allows you to get out of situations.
        I like at least ¼ throttle to touchdown.
       Set your timer conservative. First flight should be short so
        you have little chance of going into battery LVC.
   In short, fly it like a jet and things will go well.
EDFs at Altitude
What Combo is Right?
   Some stock RTF planes will be sluggish at our altitude. Typically a
    motor/ESC upgrade will solve the problem.
   Nowadays some larger 90mm and up RTFs will do ok stock – upgrades
    are an option to get better performance.
   Thinner air can increase RPM/current draw compared to sea-level data.
   EDF combos I’ve used at altitude with great success:
       XF 55mm 3-blade fan w/ Don’s wicked extreme 5400kV on 4s - easy 100+
        mph (Phase 3 F-16)
       64mm “EDO” type or SF/Eflite w/ Don’s wicked 4000-4800kV motors on 4s
        lipo (Eflite F-15, FW SU-34)
       70mm HET 6904 w/ Typhoon 2W-20 on 4s (Xflight A-7, HL F-5).
       90mm HL stock setup on 6s (F-18, EF2000).
       69mm Eflite Delta V on 4s: 5s possible with new ESC (Habu) .

   www.donsrc.com has lots of eagle tree power/current data on motor-fan
    combos in different sizes. Use as a good starting point.
   Experimenting yourself will also give you invaluable data (simple thrust
    stand can be built).
Advanced EDF Info
   EDF does not compress air like a turbine, just forces it through
    the fan.
   Fan housing mitigates blade tip losses and allows higher
    operating RPM. Not as much unloading in the air like a normal
    prop.
   Clearance between blade tips and housing is important. Less
    clearance = more thrust. Centering the fan rotor is also crucial.
    At high RPM the blades will actually stretch out.
   Efflux/exhaust velocity governed by the thrust tube’s area versus
    the FSA (fan swept area).
   Smaller thrust tube diameter sacrifices thrust for higher max
    speed.
   Typical thrust tube/tailcone is about 80% FSA (more speed) to
    90% FSA (more thrust).
   Anything impeding exhaust airflow will result in turbulent flow and
    greatly reduce thrust.
   Some EDF airframes do not have sufficient inlet ducting to “feed”
    the fan. In this case the plane has “cheater” holes – these allow
    enough air flow into the fan so it is not starved. The holes
    increase static thrust but should not be made too large.
What Else?
   Many models today have built-in thrust vectoring for
    aerobatics (high alpha, Cobra, flat spins, Harrier)
   If you are a speed junkie, EDFs can easily satisfy
    your speed appetite (foam up to 160 mph, glass up
    to 200+ mph)
   Scale flight is overlooked. Look ma, no prop!
   EDFs allow you to fly in short order w/o going
    through time-consuming fueling, assembly, and
    starting procedures (convenience factor).
   If you are looking to advance into turbines, EDFs
    offer an economical way to “fly-before-big-buy”
    (EDF=$100’s, turbines=$1000’s)
   Most EDF planes (even small ones) have flight
    characteristics like their larger turbine counterparts.
Beginner Foam EDF Models
   Phase 3 F-16 –
    www.hobbypeople.net

   Phase 3 U2 –
    www.hobbypeople.net

   ParkZone Habu –
    www.horizonhobby.com

   Hobby Lobby - Executive jet
    (SFM), EF2000 eurofighter
    (FreeWing), F-35.

   Others include C-17, F-86,
    Twister, etc
Accessories for Getting
Started
   ESC programming card (set up LVC, motor timing)
   Wattmeter (check motor current draw)
   LiPo batteries – 30 to 40c if available
   LiPo balance battery checker (field check batts)
   LiPo battery balance charger
   Real-time battery monitor (Quanum, Hitec,
    Weatronics). Helps you monitor battery voltage and
    avoid surprise LVC.
   Eagle Tree logger (for more advanced testing)
    Some Web Sites
   Don’s RC: www.donsrc.com Everything EDF up to 70mm
    Wicked motors are some of the best. Hobbywing ESCs
    and dynamically-balanced fans.
   Hobby Lobby: www.hobby-lobby.com Mostly ARF/RTF
    planes.
   HobbyCity/HobbyKing: www.hobbycity.com Tons of fans and
    motors to choose from. Turnigy ESCs, Lipo batteries,
    chargers, etc. Also has wattmeters, Quanum telemetry unit.
    Economical way to get into EDFs.
   Turbo Fan Electrics: www.turbofanelectrics.com Lots of
    planes, HET fans and motors.
   Philip’s workshop: www.pw-rc.com Great customer service
    and offers newest jets at a discount, Hobbywing ESCs.
   Electric Jet Factory: www.ejf.com Good selection of
    different-size and type of EDFs, motors, planes.
   Tamjets: www.tamjets.com Example for getting into larger
    (and more expensive) EDF planes 100mm+.
Have Fun!   (Q&A after Sid)
      Introduction to
Turbine Model Flying
              Sid Gates
            AAM Meeting
               1/4/2011
Turbine Engine Components
   Most current
    production engines are
    Single Shaft with an
    annular combustor.
   The Single Stage
    Centrifugal Compressor
    is driven by a Single
    Axial Flow Turbine
    Wheel.
   The shaft is supported
    by two lubricated, pre-
    loaded angular ceramic
    ball bearings
Turbine Engine Disassembly
   Compressor and turbine wheel installed on the
    shaft
   No bearings shown.
Turbine Combustor

   Annular Combustor – The
    combustion chamber is
    made out of stainless.

   The hole pattern is
    designed to control the
    size and shape of the
    flame in the chamber.


                              Side View
Combustor with Injectors
   Fuel feeds in through the small tube
    shown on top and goes into a fuel
    manifold that goes around the back
    of the combustion chamber.
   Twelve stainless fuel injector needles
    are silver soldered into the fuel
    manifold.
   The ends of the needles are placed
    into the rear of the twelve vaporizer
    tubes.
   The vaporizer tubes are soldered to
    the back of the combustion chamber
    and run approx. ¾ of the way to the
    front of the combustion chamber.         Side View
   Vaporizer tubes atomize the fuel for
    sustaining “well-behaved” flame
Turbine ECU
   An Electronic Control Unit (ECU)
    monitors exhaust gas
    temperature, RPM, ambient
    pressure and controls the fuel
    pump voltage.
   The miniature fuel pump in turn
    controls turbine speed (thrust) by
    varying its RPM and the fuel flow
    rate.
   The ECU acts as an electronic
    speed control so that fuel pump
    speed is proportional to the
    transmitter throttle stick position.
Turbine Compressor

   The spinning compressor
    pumps air into the case.
   Air is compressed (density
    increased) and passed to
    combustor for fuel/air mix.
   The diffuser shown below
    straightens the air flow as it
    goes into the case.
   The sleeve that houses the
    shaft is shown attached.
Turbine Engine Disassembly 6
   The diffuser is shown on the front (left) of the
    combustion chamber and the Nozzle Guide Vane
    (NGV) on the back (right) of the chamber.
Turbine Engine
RAM 500 engine disassembled (~12 lb thrust)
Turbine Operation
   Test stand with engine
    and all components
    necessary to run.
   The engine can be run
    from the data terminal or
    the transmitter.
   The start/run sequence
    to be described is for the
    RAM 500, others vary
    slightly.
Start Up Sequence
   The start up sequence can be
    initiated by the Data Terminal
    or the Transmitter.
   First the electric starter motor
    spins the engine up to
    approximately 6,000 RPM then
    cuts off.
   The engine is allowed to coast
    for a short time and then the
    ECU pulses the propane (gas)
    solenoid and lights the glow
    plug.
Start Up Sequence (cont)
   The propane lights and the
    engine accelerates to approx.
    15,000 RPM.
   If the RPM and temperate are
    rising the ECU starts pumping
    fuel (Kero or Jet-A).
   The Data Terminal will then
    display “RAMPING”.
   When the engine reaches
    50,000 RPM the Terminal will
    display “RUNNING” and you
    have transmitter control of the
    engine.
Model Suggestions
   You have the best chance of
    success if you start with a         A slightly higher performance
                                        choice and the lowest initial cost is
    trainer jet such as the             the Tornado package offered
    Boomerang Sprint ($795.00)          by Modellbau USA
    for the 12-22 lb thrust engine.
   If you start with a larger engine
    the Boomerang Elan or XL are
    very good choices. Slower
    landing speed and lighter wing
    loading.
   If you are only interested in a
    military scale model I
                                        Tornado Sport Jet Comb Package Model is
    recommend the Top Gun F-15          a redesign of a model that re- quired a lot of
                                        mods for turbine operation. Engine is a
    or any F-15 available (Yellow,      proven design.
    Fei Bao, Avonds)
 Choosing the Right Engine
1.   Decide on your budget.           Purchasing New vs Used:
2.   Decide what size models and
                                         There has been rapid
     whether Sport or Scale.              improvement in engine design
3.   Your model choice will dictate       the past few years.
                                         Faster acceleration, lighter
     the size of Engine.                  weight and better fuel
4.   Chose the brand of Engine.           economy.
        Main Stream Brands:              Make sure you know the
                                          engine designs short comings if
               Jet Cat                    buying an older used engine.
               WREN                      ASK/CONFIRM used engine
               Jet Central                has not been in crash or if was
        Newcomer:                         serviced afterwards
                                         Web searches are a good
               Kingtech                   place to research an engine.
AMA Turbine Waiver Summary
   Turbojets and Turbofan single engine models shall not exceed static thrust
    of 45 lbs. & multi engine shall not exceed 50lbs combined

   RC fixed wing aircraft: The maximum velocity will be 200 mph.

   All radios must be equipped with fail safe and the ECU shall be configured
    to shut down the engine within 2 seconds of fail safe activation.

   An experienced turbine pilot is defined as a pilot who has completed 20 or
    more turbine flights during the preceding 24 months and who has a current
    turbine waiver issued by AMA. For confirmation purposes, the pilot is
    required to keep a written log of all flights and will provide copies to AMA
    upon request.

   An AMA member may be permitted to fly a turbine powered model on the
    slave transmitter of a buddy box as long as the master transmitter is
    operated by an experienced turbine pilot. All turbine waiver applicants
    should have accomplished at least 50 flights on a high performance model.

   Fixed wing: Model should be capable of sustained speeds of 100 mph or
    higher.
AMA Waiver Flight Demo
    The purpose of the flight test for the turbine applicant to
     demonstrate their skills, knowledge, and understanding of
     how to safely operate and fly a turbine model aircraft.

    Key Elements: The following elements are to be demonstrated
     through action along with verbal discussion of the element where
     appropriate.

1.   Demonstration of proper turbine ground operations

     a.   Discuss the need to keep the tailpipe area clear of people and
          flammable items during start, shutdown, and all ground operations.
     b.   Explain the response plan for dealing with an aircraft fire similar to one
          resulting from a hot start. Fire extinguisher to be present per AMA
          safety regulations.
     c.   Explain the potential for a post crash fire and the response plan to deal
          with the situation. Explanation to include local fire department contact
          number and fire fighting equipment immediately available for the
          modeler to respond to the fire.
     d.   Explain and demonstrate typical turbine startup and shutdown
          procedures.
AMA Waiver Flight Demo (cont)
2. Flight Skills
   a.   Takeoff, to be held within 10 feet either direction of centerline, with
        smooth, controlled corrections as necessary.
   b.   Horizontal Figure 8. Pilot to hold altitude to within +/- 50 feet during the
        Figure 8. This demonstrates skills at both left and right hand patterns
        and the ability to control the models flight path.
   c.   Perform two aerobatic maneuvers with combined looping and rolling
        elements to be selected by the turbine applicant. Examples include
        Cuban 8, Humpty Bump with ½ roll, or similar maneuvers. This
        demonstrates the general flying skills of the modeler.
   d.   High Speed Circuit of the field performed at a safe high rate of speed.
        This demonstrates the ability to control a model aircraft at speed.
   e.   Square Traffic Pattern including a missed approach go-around. This
        maneuver to be in the opposite direction of the takeoff and landing if
        conditions allow. This demonstrates the ability to control a model
        aircraft in the landing approach mode.
   f.   Landing to a complete stop. Again, smooth, controlled corrections to the
        aircraft’s path after touchdown are required. The landing must be
        completed on the runway.

         * At no time during the flight shall the aircraft pass behind the
                               designated safety line.
Thanks!


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