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Jul 29, 2017, 10:06 AM
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Phoenix Pilatus PC-9 Unbox, Build Review and Maiden


My all time favorite plane for daily flying is the Tower Hobbies Millennium Master. That plane goes with me every time I fly. I've been looking for a step-up successor for the MM now that I have access to a paved runway and a much larger flying field. The Pilatus PC-9 checked a lot of boxes for me:

1) Phoenix Model - They make solid ARF kits. Covering has always been very good and requisite hard points (landing gear, motor mount, wing joints) always seem to be built strong.

2) Low Wing - The MM has a low swept wing. The PC-9 has a low moderate sweep with dihedral. So it may not be as docile inverted as the MM but I don't fly inverted that much anyway; and, I'll get the added stability benefit of moderate dihedral with the PC-9.

3) Tricycle Retracts - Trikes lend themselves well to paved surfaces. The MM has fixed tricycle gear, the PC-9 has retract trike gear. Big plus on this point.

4) Balsa Construction - In my new location, wind is more of a factor than it used to be. Balsa planes just fly smoother in windy conditions. They're also more resistant to hangar rash.

5) Bigger Motor/More Speed - The PC-9 is a .46-.55 class plane, so I can use a bigger motor, higher cell count, and fly faster - However, the MM is no slouch with a 3s 9x7 on the stock motor.

I know there are other sport planes that check some of these boxes but the PC-9 checked most of the boxes for me as a successor. As of this writing, I've just started the assembly. I'll post the build review and maiden flight videos as soon as they happen. Build notes on current progress are below. For now, enjoy the unbox video.

Phoenix PC9 Pilatus Unbox (15 min 20 sec)



Build Notes:

- Every Phoenix plane I've built so far has the electric motor mount pre-drilled. This is a nice touch if using a Rimfire motor. I've had good success with Cobra motors, so the 4120 700kv was my choice for this build. Of course, the cross mount doesn't line up to the pre-drilled holes. It's an easy enough fix. After gluing the three ply sheets together ensuring the holes line up, I fill the pre-drilled motor mount holes with 6 minute expoxy. Then I use the Cobra mount as a template to drill 4 new holes. One or two of the holes gets a little close to the edge of the ply, but not close enough to be concerning. I usually use a hearty set of cutters to trim a flat edge in the standoff washers so they sit flush on the wood instead of riding on the motor mount washers.

- The standoff hex bolts protrude aft of the main firewall about 1/2" into the battery compartment. Two problems with this. #1 The forward end of the battery hatch sits against the firewall. With the mounting bolts protruding out the back of the blind nuts, it prevents the hatch from seating. So they have to be trimmed to be flush with the blind nut. 2# The lower screws could easily come into contact with the battery, so they must be trimmed too.

- The Cobra can is shorter than the Rimfire can. To get clearance for the spinner backplate I had to use two washers under each of the motor mount holes to push the mount forward. I also used the prop washer as a spacer by placing it backwards on the prop shaft against the prop adapter followed by the spinner backplate, then the prop, another prop washer, and the nut. I have about 2mm of clearance now, and it looks great!
- I purchased a 2 1/4" aluminum backplate spinner from Amazon. That is the correct diameter for the cowl opening. It lines up nicely.

- This build has been fighting me at every turn. The cowl just doesn't fit well. I spent an inordinate amount of time trying to find balance between getting the cowl to sit flush against the battery compartment lid while keeping the prop shaft centered. Just wasn't happening. I had to compromise. The cowl radius sits a touch high against the spinner backplate. You can see the gap in the attached pic between the cowl and the battery compartment lid. I also had to cut a rectangle in the lower cowl over the nose gear to allow the retract to extend to the open position.

- The wing bolt holes were not lined up correctly. I found this out taking measurements from the horizontal stab to the wing tips. Once I got that measure equal on both sides, I stepped back and saw the horizontal stab was far from perpendicular to the fuse. While inspecting the main wing arrangement in the wing saddle I realized the wings were not perpendicular to the fuse. After hogging out the wing bolt holes, I was able to get the leading edge seated squarely, then the horizontal stabilizer squared up.

- The horizontal stab was not parallel with the wings either. I had to cut/sand the horizontal stab on the starboard side lower and the port side upper cradle to get it level.

- The vertical stab required work to get the forward fin to sit flush on the fuse and to get it mounted at a right angle to the horizontal stab. So far, this has been the most non-square Phoenix plane I've built. I don't mind doing the work, it's part of modeling; however, I've never had to square up a Phoenix model like this before so it's been a little surprising.

- All the servos are installed. I went with the HK servoless retracts linked by dbc in the PC-9 thread. Just as he states, they are drop-in replacements with a small amount of dremel drum sanding to fit the housing. The main gear struts bolt directly onto the HK retract pin. The wheel well cover stand-offs don't fit though. They will need to be cut because the gear sits too close to the worm drive to accommodate the back of the stand-off.

- Make sure to get the correct number of servos. The front wheel gets a dedicated servo that gets connected via Y-cable to the rudder servo. So, 2 aileron, 1 rudder, 1 elevator, 1 nose wheel, 1 retract for mains, 1 retract for nose wheel. If you go with the HK servos, you eliminate one retract servo.

- The wiring takes time as the Rx goes in the belly aft of the wing. It takes a while to fish the servo wires to the Rx compartment.

- My nose gear steering servo turnbuckle on the port side rotated perpendicular to the fuse with the nose wheel retracted. This caused the turnbuckle to push into the side of the fuse against the balsa and occasionally jam while operating the rudder. I fixed this by putting a counter clockwise twist on the steering wire and by gluing a 1/2" by 3" plastic card (blank gift cards from Amazon) to the side of the fuse. Now there is nothing for the turnbuckle to get hung-up on.

- I didn't use link stoppers on the servo horns, I opted for Z bends instead. The clevis on the control surface horns is adjustable. This eliminates a point of failure.

That's about it for the highlights of this build. Just waiting for an ESC and I can go fly it. Keep an eye here for the maiden video.
Last edited by jmxp69; Sep 04, 2017 at 06:01 PM.
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