Vario Chinook on the Table

I didn’t start at the beginning but still thought it would be fun to share my progress on the Vario Chinook. The mechanics are FUN! The parts are intelligently packaged and the instructions are a pleasant departure from some older Vario models I’ve had.

I plan to build and fly the mechanics separately before even attempting the fuse.

You can order the Chinook from Mark Smith of HeliWorkshop.com! Mark knows his stuff and offers help from his decades of experience.

I probably sound like I’m building my first RC heli kit but it’s hard not to gush a little bit when describing the construction of the Vario Chinook mechanics.

Vario’s drive system for this tandem looks solid with a stout main drive shaft that drives two disk gears with spiral teeth. The pushrods for each swashplate are all angled at one end because they must pass through a narrow aperture from the servos and then wing out to meet the ball links on the swash. The servos each drive two pushrods with an ingenious double ball link on each arm.

Once I get the left frame on, I’ll begin the critical stems of ensuring that each swash is oriented 90 degrees from its respective shaft. The front shaft tilts forward so I’ll shim up the front of the fuselage to calibrate the front rotor.

I intend to fly this beast without the fuselage so I will complete the setup of the mechanics only. I mounted the gyro in the center of the mechanics so it should be easy to access with a small servo extension.

I’m still waiting on the rotor heads but I was able to program the ESC and the gyro without them. To fit the mechanics into the fuselage while waiting for the heads, I’ll remove the front shaft and slide the mechs in. Lots of measuring and cutting to go!

Notice that I applied double sided foam tape where wires could rub against the sharp aluminum edges.

UPDATE: I rotated the Demon 3SX so that it's mounted against the mechanics vs the battery tray. Although the Axon can handle transverse mounting (like I show here), the 3SX cannot. Also, note the location of the gyro in the center of the mechanics. After conferring with Demon and an RC electronics expert, I am comfortable that the proximity of the gyro to the batteries is NOT a potential interference risk.

In constructing the Chinook, I've noticed a number of modeling opportunities (and by that I mean opportunities for you to get out your Dremel and sanding boards):

1. Prepare to slide the mechanics in and out of the fuse A LOT! I recommend removing the front pushrods to make the slide easier.

2. Although not specified in the instructions, I recommend removing most of the flange areas on the front and back. As the photo shows below, I left about 1.5" of flange at the top for anchor bolts but otherwise removed the fiberglass to make getting the fuse in and out easier.

3. When testing the fit of the fuse, keep all mounting cleats LOOSE until everything is connected; then you can torque down the bolts.

4. BUY A COMPASS/SCRIBE to make the precise circle cuts in the two top domes. You'll thank me later. Sure, you can trace a cup or some other thing, but the scribe lets you get things precise and score the fiberglass for easier cutting.

5. I replaced the included wheels (hard foam) with DuBro 2" Low Bounce Treaded Tires. They look great; I'm not sure whether they will develop flat spots. 😬

6. For drilling the circular openings for the landing gear legs, I recommend a step bit! makes for easy work.

I've been in the hobby for 50 years. This was my FIRST time attempting a build on a Vario. Cutting and sanding fiberglass, gluing formers and doing what I call "artwork" is something I shied away from until now! It is fun! I've always enjoyed mechanics, fuel systems, electronics and all the other shiznizzle but the glasswork was interesting. I have shipped my Chinook off to Tyler Gray Models for the beauty work. THAT, I'll never do!

It's been awhile since my last chapter! I completed the mechanics and went to test fly them. A couple of things went seriously awry:

1. The pitch recommendations in the instructions (-4 to +12) are a bit too much at the bottom in my opinion. I had -4 set and had forgotten to put in expo on my initial flight. After rearing back like an angry thoroughbred, I dropped collective too quickly and the front rotor crushed the top and side aluminum frames. It also screwed up the head so I ordered replacement parts.

2. Meanwhile, Tyler Gray was working on the paint, fiberglass, fittings, lights, sound and scale details.

3. I receive my parts and after putting off the inevitable deconstruction-reconstruction process, I did it. I spent several hours dialing in the blade pitch and swapped the Vario pushrods for Secraft turnbuckles. This allowed me to get within a 1/10th of a degree on each blade.

4. The maiden was truly uneventful. She lifted straight up and hovered perfectly. I did not fly the mechanics because I was certain I would lose orientation and destroy it. Now back to the shop for final fitment.

5. Getting everything together is a bit of an ordeal. You have to unbolt the entire front shaft stack in order to slide the mechanics into the fuse. You also have to remove the landing assemblies. Arranging the sound board, light board, receiver and batteries (for sound and lights) is fun, but painstaking. In addition, I burned out my landing lights so I needed to install new ones.

6. Once complete, the model is ready to go! I left off the spinning rotor caps for now because the turnbuckles are a bit wider than the apertures for them and I have no patience for disassembling the heads.

HOW YOU LIKE ME NOW?!

This past weekend, I took the Chinook out to the field for its first fully clothed ascent. After an initial 30-second hover, I went to take off again when, at full rotor RPM, the front rotor SEPARATED from the main shaft. On its way off the model, the front rotor collided with the rear and made straw out of my blades, but incredibly there was no other damage to the model.

[SINCE I FIRST POSTED THIS, I LEARNED THAT MY INCIDENT IS DIFFERENT FROM WHAT OTHER PILOTS HAVE EXPERIENCED]

I have written to Vario about this incident. Kirsten has responded and I'm in conversations with their team pilots to determine the cause. I did use thread locker but I cannot determine why this happened or whether or not it will happen again. Sandy Jaffe (team pilot) has 300+ flights on his model with no incidents.

More to come...