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Scale RCM 1/3 Scale Champ Build

Discussion in 'Giant / Scale Scratch and Kit Build Threads' started by TonyHallo, Jan 5, 2019.

  1. dhal22

    dhal22 GSN Sponsor Tier 1

  2. Working on the radio installation, both receivers are located under the back seat, connected the RB 10 redundancy bus located in the front of the plane under the dash. The elevator and rudder servos were relocated under the dash and are accessible by removing the boot cowl if needed. The pull-pull cables travel thru Teflon tubes under the floor. A Tech Aero IBEC will complete the control portion. The Hobby King 7.4 volt 3P2S batteries fit great under the front seat, rated at 10 C should be adequate to power the plane. An Advanced Telematix AT-V1 telemetry board is used to monitor the cylinder head temps and the ignition module temperature. According to the Roto manual, the ignition module will shut down above 140F, will set an alarm at 130F.

    Measuring the third temperature has been quite a challenge. The device comes ready to measure 2 temperatures, 3 voltages (0 to 5 volt), and 1 RPM. The manual states that the third temperature can be enabled with a re-flash, no problem. There's not much out there on the web about this device but did find a kind gentleman that provided re-flash instructions and the file. Download the required program and purchase the adapter to communicate with the Ardunio, after a couple of hours, success! Down to basement to give it a go. Doesn't work as claimed. All there temperate ports are active and the indication on Temp 1 is the lowest temperature of the there sensors while Temp 2 reports the sensor number with the highest temperature. Not sure how this could be useful, maybe someone out there does and can shed some light. Was also in contact with Aloft Hobbies who sells the device, they sent me a different version of the code but operated in the same manner. They are contacting the manufacturer and will hopefully find a solution.

    Decided the third temperature could be measured with a voltage divider circuit using one of the voltage inputs. The AT-V1 has a 5 volt power supply for RPM probes that require such as the Eagletree. This was turned on with a jumper, a 100K ohm resister in series with the 100K ohm thermister is used. Voltage readings across the 100K resister are used to indicate the temperature. Voltage readings were taken in the 120F to 150F range and some messing around with the ratio in the telemetry appear to have a very accurate indication in the range needed. Indications outside this ranged are inaccurate.

    IMG_1048.JPG IMG_1049.JPG
    AKNick, WMcNabb, pawnshopmike and 2 others like this.
  3. AKNick

    AKNick 640cc Uber Pimp

  4. AKNick likes this.
  5. As part of moving the servos forward decided to make a new stabilizer and elevators, needed to make revision to elevator to accommodate the pull-pull anyway. The resulting parts weight a little more than 3 ounces less than the original. The original is on the right side.
    Also found the micro piano hinge at Micro Mark make by Dumas. This is going to work great the elevator trim tab. There is a groove routed under the plywood cover that will accept the hinge after covering and painting. It will make more sense after the tab is cut free
    IMG_0215 (1).JPG
    -Rick-, Snoopy1, WMcNabb and 2 others like this.
  6. The trim tab is cut free and the piano hinge fitted. Need to hinge the elevators and make the control horn for the tab.

    Snoopy1, AKNick, pawnshopmike and 2 others like this.
  7. Working on the trim tab pull-pull set up. Using the three view and photos collected tried to duplicate the full scale, was pretty sure it wouldn't work as hoped and darn if I wasn't right. The top pull passes through the elevator to a pulley on the bottom of the trailing edge of the stab. The bottom pull simply connects to the pulley. As the elevator goes through the travel range, both cables get tighter with up elevator and looser with own elevator. I really wanted this work but not the case. I wonder how cable tension is maintained on the full? scale?
    Made up a sliding mount for the trim tab servo that will be pulled by a spring to maintain cable tension. The servo will either be connected to the trim switches or slaved off the elevator to act as a boost tab, haven't decided yet. Leaning towards the boost arrangement. Any thoughts out there? The servo will be located up front with the rudder and elevator servo.
    Going to make slightly larger plastic pulleys and get the sliding tray mounted once the glue dries.
    Once this is resolved time to cover the fuselage.

    Last edited: Dec 4, 2020
  8. Finished the trim tab installation, made larger pulleys with deeper grooves. The sliding servo mount is shown as well. Decided to mix with servo with the elevator trim tab rather than boost mode. In either mode the cables remained on with elevator travel 30 degrees in each direction so I'm good with that. Forgot I need to make new tail brace wires, there's been a lot of prototyping here for sure. That's OK expect to have this plane the rest of my life!

    IMG_1065.JPG IMG_1066.JPG
    AKNick, WMcNabb, -Rick- and 2 others like this.
  9. Holy smokes. That is one intense build brother. I’d never have the patience. Very cool.
    dhal22 likes this.
  10. WMcNabb

    WMcNabb 150cc

    TN, USA
    Full scale should have the cables traveling with the elevator and not connected to the horizontal stabilizer.
    Most of the aircraft with which I’m familiar use a rod instead of cables, but let me see what I can find.

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