FlexJet Pro Turbine Conversion Assembly

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FlexJet Pro Turbine Conversion Assembly Notes

The following is an outline of the steps needed to convert the FlexJet Pro ARF to a turbine operation. These instructions supplement the main assembly manual. Many steps can be accomplished in a different order.
Read through ALL instructional information before beginning assembly!
NOTE: The aft separate piece of the inlet duct is not used when using the gas turbine.

Mount the Turbine

NOTE: The EDF mounts can be left in place. It is even feasible to convert the model from EDF to Turbine and vice-versa. The Turbine can be installed through the fan hatch which provides valuable additional access.

  • Plywood Conversion Parts kit can be purchased here.
  • Dry assemble and test fit the Mounts.
    • Fit the parts together as shown and check the fit in the model. Adjust the parts as needed for a close but relaxed fit.
      • The Turbine/Plate may be mounted with screws of the modelers choosing. We used 4-40 SHCS's with Washers and Blind Nuts. Others may choose Sheet Metal Screws (#3 or #4). Screws are easily accessed through the Main Landing Gear Doors. Screws that accept a ball end hex driver are greatly preferred.
      • Doublers are provided to thicken the Mounting Rails in the screw area.
      • A JIG PLATE is provided to substitute for the Turbine and to hold the parts square during fitting and gluing. Typically it can be mounted to one side of the turbine mounts, installed in the model, then the second turbine mount can be screwed into place.
      • The TWO holes per side on the Rails are used for the KingTech K45G3 and the JIG PLATE. Lines are etched into the part, To Clear the KingTech Mount parts, you will want to cut the Rails back to these lines.
      • The THREE holes per side are for the Xicoy X45 (based on factory drawings, please test fit)
    • With the Jig Plate still in place, mark two sets of lines at the back of the Rails for tailpipe mounting. Make one set 7mm (primary) and one set 11mm (alternate) forward of the aft most edge of the rails.
      • Center the tailpipe mounts between the rails and mark the width of the hole locations on the lines made just above.
      • Drill four holes (two primary and two alternate) for the tailpipe mounts in the rails and test fit the screws to make it easier to install them later. (#3 or #2 Socket Head Sheet Metal Screws are a good choice, small socket head machine screws and blind nuts could also be used.)
  • Once the parts are fitted, glue the Mounting Rails to the Sub-Formers as shown using CA.
    • Install the mounts into the fuselage again and glue the sub-formers to the fuselage with Epoxy.
      • The exact fore/aft distance of the mounts is set with the 75mm long Plywood Strips included which go forward to the main landing gear mounts as shown. These can be glued in at a convenient time with CA or Epoxy. (Make sure they are far enough into fuselage so they do not interfere with Door Actuation).
      • Use a 15-30 minute or greater epoxy. You can use a thixotropic epoxy such as Hysol 9462, or thicken conventional epoxy slightly with milled glass fiber. A long popsicle stick or balsa stick can be used to apply and spread the glue.
    • Once the glue is well cured, remove the Jig Plate and test fit the Turbine.

NOTE: Fitting is easier and small alignment adjustments can be made if the holes in the turbine mounting lug tabs are drilled slightly oversize.

Mount the Tailpipe

  • Tailpipe can be purchased here.
  • Test fit the Plywood Ring over the back of the tailpipe. Adjust fit as needed. (Slightly loose is OK)
  • Test fit the Plywood Ring into the removable Nozzle. Adjust fit as needed so it seats well
  • Glue the Plywood Ring into the Nozzle. (It can be spot glued in 8-12 places, it does not need a lot of glue)
  • From the aft end of the model put the tailpipe into the fuselage.
  • It is easiest to install the Nozzle onto the Tailpipe then bolt the Nozzle to the Fuselage while the tailpipe is still loose and somewhat aft.
  • Screw the Tailpipe to Rails. The hole alignment can be tweaked slightly by bending the aluminum mounts or bellmouth.
  • Check the Tailpipe alignment to the engine. It can also be tweaked by bending the aluminum mounts or bellmouth.

NOTE: The aft edge of the turbine nozzle should be about in the middle of the tailpipes aluminum bellmouth.

Fuel Tanks

  • Generally, you will follow the instructions from the fuel tank manufacturer. The following supplemental information is provided for reliable turbine operations. This shows techniques used on the SS-6 Collector Tank (S738).
    • Make sure you use stoppers (like Sullivan S449), lines, and hardware intended for gas/petrol/kerosene/diesel. BVM has a very good fuel line for use on Turbine Clunks. 1/8" Large Tygon fuel line can also be used.
    • Barbs and Safety Wires make connections secure and leak free. Air leaks in the system are a major cause of flameouts and loss of models! Take your time and build a reliable fuel system!
    • Note the barbs on tubing are made from an over-size tube and soldered on.
    • Note the vent line has relief cut to prevent it from sealing on inside of tank and blocking flow.
    • Note the Petrol compatible stopper.
    • Safety wire is recommended for all connections. It helps make lines secure under pressure and vacuum and prevents leaks.

NOTE: (Review images below also) It is possible to have the Vent Line of the collector tank exit directly upwards thus eliminating the U-shaped tube joining the vent of the Collector Tank to the Clunk of the Main Tank.

  • Using the 24oz Plastic Sullivan Tank
    • Internal assembly uses the same techniques as above.
  • Using the 35oz Flex Innovations Composite Tank
    • Photo taken before safety wired added
  • It is easiest do to the final tank installation and final plumbing and safety wiring after the engine and forward equipment tray are installed.

Typical Flow to Turbine:
Air Vent/Overflow on bottom of aircraft
->Vent of Main Tank -> Clunk of Main Tank
->Vent of Collector Tank -> Clunk of Collector Tank
->Vent 1 of UAT ->Output of UAT (Vent 2 of UAT is the Fuel FILL point)
->Adapter of Tygon to Turbine supplied Fuel Line (if required)
->Fuel Pump Inlet ->Fuel Pump Outlet
->Fuel Filter Inlet ->Fuel Filter Outlet
->Fuel Shutoff Inlet -> Fuel Shutoff Outlet
->Line Size Adapter Inlet -> Line Size Adapter Outlet
->Turbine Engine Fuel Inlet
NOTE: Use CAUTION if using vent plugs. Temperature changes can cause fuel tank damage and ruptures. Forgetting them and filling can cause fuel tank damage and ruptures. Make sure vents are open and clear during all operations.

Equipment Tray

  • Assemble the components to the forward equipment tray. Our recommendations follow. The majority of this work can be accomplished more easily with the Tray NOT mounted in the model.
    • The Aura Professional is mounted at the right rear part of the tray. Mounting holes are marked.
    • The Aura Remote Sensor is mounted on the right toward the front of the tray.
    • The Receiver can be mounted in the middle of the right side of the tray. We mounted the Retract Sequencer to the side wall nearby (it could also be mounted inside the Lerx/Chine. The Brake Controller can also be mounted in the Lerx/Chine
    • Arrange servo wires to go out into the chines so they are not chafed by the fuel tanks. They can be organized and held in place with a combination of hook and loop cable ties and sticky back hook and loop.
    • The Turbine ECU is mounted at the rear left. This allows us to use the K45G3 wiring harness with no major modification (We installed an EC3 battery connector). If you have a larger ECU, you could build a mount to install it more on its side edge.
    • The 2oz UAT (air trap) is mounted in the hole in the middle left side of the tray and secured with a hook and loop strap. The front of the UAT sits a bit up, and the rear a bit low.
    • The Fuel Pump is mounted at the front left side of the tray and hangs off the front. This improved the CG and allows more room for fuel lines and filters.
    • The Fuel filter can be seen on the output of the pump, followed by the Shutoff Valve beside the UAT (Under the wires).
    • There are a few places a Radio Power Switch can be mounted if you want one... perhaps just behind the Remote Sensor on the extreme right. Consider the retracting wheel and the formers and components underneath when locating. If you want it in the tray, it is easiest to add it before final installation. (A switch could also be installed on the sidewall or in the Lerx/Chine.)
    • The Batteries are mounted on the Battery Plate in the nose using the stock aircraft method. We mounted one battery on top, and one on the bottom of the Battery Plate

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