Hoomi
Master member
A few weeks ago, I went to Phoenix for the fall swap meet of one of the clubs out there. I came home with a used model of the T6 Texan II trainer aircraft, from Unique Models. This is a reasonably nice looking model of the plane, with some interesting features, and the seller gave me a reasonable deal on it.
That said, it definitely needed some repairs.
One of the "gee golly wow" features this model came with, was a motor-actuated lift for the cockpit canopy, in order to install the flight battery. To accomplish this, the plane has an XT60 connector mounted on the side, just below the cockpit on the left side. When it was new, you could connect your battery to that connection, and the sequencer module inside the plane would open the canopy battery hatch. You'd then move the battery to the inside, connect it to another XT60 connector in the battery compartment, and then the motor would close the battery hatch.
This same sequencer was used to control the retractable landing gear, but based on reviews I've read, was a notorious point of failure on the model. The sequencer in the one I bought does not work, and I had to remove the wing to get to the connector, in order to hook a separate battery to it to open the hatch.
The retracts are basic DC motors, with JST connectors that hooked them to the sequencer. Direction of retract motion was determined by the polarity of voltage applied to the motor, rather than the modern convention of servo connections that work directly with the plane's receiver.
To bypass the inoperable sequencer module, I bought some copper-clad circuit board. I cut a hole in the board to pass the top of a servo through, and attached electronic wiper contacts to a long, two-sided servo arm. Using a Dremel, I removed the copper from most of the board, leaving two parallel strips. One strip connects to one side of a trio of JST connectors which mate with the retract connectors, and the other strip connects to the other side. The wipers are connected to a regulated BEC connection from the ESC, and the servo control connected to Channel 5 on the receiver. I have Channel 5 controlled by a three position switch, with the travel limits set so that when the switch is activated, the servo moves the wipers to connect power for either retract or drop the landing gear. Once the landing gear motion is finished, the switch is moved back to the center position, thus removing power from the motors.
A switch in the nose wheel well detects when the nose wheel is retracted, and is supposed to disable the nose wheel steering servo. This switch was wired wrong, so that the nose steering would only move when the landing gear was up. This not only would make it difficult to control the plane on the ground, the nose wheel strut interfered with the steering servo when the gear was retracted. I rewired the switch, so that the servo is now disable when the gear is up, and works with the gear down.
I repaired the old hinges on the canopy/battery hatch, and disconnected the motor for opening/closing it. Instead, I installed a magnet system to hold the canopy closed. The feature was nifty, but definitely did not follow the classic K.I.S.S. rule. If something goes wrong, I don't want to have to putz around with an electric motor hatch control, in order to get to the battery and disconnect power to the plane.
Currently, instead of the 10.5X8 four blade prop the plane originally came with, I have a 12X6 two blade installed. I think this should still provide more than enough thrust for the plane to fly well on the 4S power, and I have a nice spinner that looks good with the plane. I have not yet been able to find a 4 blade spinner that would fit well for this model.
Photos to follow later today. I'm hoping to have a chance to send it up for a restoration maiden this weekend, but we'll see how it goes.
Until then, here's an older YouTube video reviewing the Unique T6 Texan II, from 2012...
That said, it definitely needed some repairs.
One of the "gee golly wow" features this model came with, was a motor-actuated lift for the cockpit canopy, in order to install the flight battery. To accomplish this, the plane has an XT60 connector mounted on the side, just below the cockpit on the left side. When it was new, you could connect your battery to that connection, and the sequencer module inside the plane would open the canopy battery hatch. You'd then move the battery to the inside, connect it to another XT60 connector in the battery compartment, and then the motor would close the battery hatch.
This same sequencer was used to control the retractable landing gear, but based on reviews I've read, was a notorious point of failure on the model. The sequencer in the one I bought does not work, and I had to remove the wing to get to the connector, in order to hook a separate battery to it to open the hatch.
The retracts are basic DC motors, with JST connectors that hooked them to the sequencer. Direction of retract motion was determined by the polarity of voltage applied to the motor, rather than the modern convention of servo connections that work directly with the plane's receiver.
To bypass the inoperable sequencer module, I bought some copper-clad circuit board. I cut a hole in the board to pass the top of a servo through, and attached electronic wiper contacts to a long, two-sided servo arm. Using a Dremel, I removed the copper from most of the board, leaving two parallel strips. One strip connects to one side of a trio of JST connectors which mate with the retract connectors, and the other strip connects to the other side. The wipers are connected to a regulated BEC connection from the ESC, and the servo control connected to Channel 5 on the receiver. I have Channel 5 controlled by a three position switch, with the travel limits set so that when the switch is activated, the servo moves the wipers to connect power for either retract or drop the landing gear. Once the landing gear motion is finished, the switch is moved back to the center position, thus removing power from the motors.
A switch in the nose wheel well detects when the nose wheel is retracted, and is supposed to disable the nose wheel steering servo. This switch was wired wrong, so that the nose steering would only move when the landing gear was up. This not only would make it difficult to control the plane on the ground, the nose wheel strut interfered with the steering servo when the gear was retracted. I rewired the switch, so that the servo is now disable when the gear is up, and works with the gear down.
I repaired the old hinges on the canopy/battery hatch, and disconnected the motor for opening/closing it. Instead, I installed a magnet system to hold the canopy closed. The feature was nifty, but definitely did not follow the classic K.I.S.S. rule. If something goes wrong, I don't want to have to putz around with an electric motor hatch control, in order to get to the battery and disconnect power to the plane.
Currently, instead of the 10.5X8 four blade prop the plane originally came with, I have a 12X6 two blade installed. I think this should still provide more than enough thrust for the plane to fly well on the 4S power, and I have a nice spinner that looks good with the plane. I have not yet been able to find a 4 blade spinner that would fit well for this model.
Photos to follow later today. I'm hoping to have a chance to send it up for a restoration maiden this weekend, but we'll see how it goes.
Until then, here's an older YouTube video reviewing the Unique T6 Texan II, from 2012...
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