I recently took the plunge into hobby-level RC helis with the purchase of a Heli-Max Axe EZ from Tower Hobbies. After putting almost two hours of actual flight time on the craft in bone-stock form, it was time to break out the Dremel and the materials bin and see how I could make a good thing into something even better.
Minor Cosmetic Mods (4/15/07)
Never satisfied! With the lower/rear fuselage/tail piece gone, the exposed bright green battery stood out like an eyesore, so I took off the covering and replaced it with some black heat shrink for a much lower-key look. While I was at it I rerouted the battery wire to effectively shorten the lead and create a neater look. I'm considering even dying the plugs black so they stand out less.
Next up, after having fun going completely horizontal with the craft a bunch of times, I returned the flybar weights to not their original positions, but the very farthest out I could get them. Now I have a stable, smooth-flying heli again. This allowed me to move the fore/aft control rod out to the outer hole on the servo horn for again faster-acting and more dramatic maneuverability. I've also now completely tightened my blade clamps, so they don't float about freely. This seems to make maneuvering a bit more crisp as well.
I broke my first couple tail fins in crash landings, so I'm on to my third. Perhaps if I break this one I'll switch to Lexan. For now, the sheet of painted styrene I'm using is very convenient and it only takes about 40 seconds to make a new one. This also gives me chances to refine the shape.
And finally, I've added some cosmetic details to the canopy. I'm using Pactra striping tape of two widths to create window seams, and I've also used a Sharpie marker to reshape the appearance of the windows slightly. In normal lighting in person, you have to know to look in order to see the difference. One of the shots I got with the bright flash shows off artificially well just where I drew my lines.
Today's photos are all caught in-flight!
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Carbon Fiber Tail Boom (3/10/07)
One of the things I really like about the Axe EZ in comparison to the competition is the body. It fully encloses the airframe with a purposeful, close fit and it looks believable and modern. However, anyone who knows me knows that when it comes to mechanical things, I don't believe in leaving good enough alone. I decided to attempt a re-styling to make the craft look more like a higher-end RC heli with a thin boom and reduced canopy.
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My first step was to remove both sections of the stock body and put the lower/tail unit in permanent storage. I sized up 195mm of 3/16" OD carbon fiber tube. At one end I used a razor saw to cut a ~10mm long slot down the center, and the other end I drilled out & tapped to accept a 4mm screw. With the tapped end starting to spliter, I wrapped tightly it a few times with electrical tape. Mounting would be simple with the help of a hole drilled through the rear bulkhead, through which the screw would be inserted from inside the fuselage, leaving the thread protruding to the rear, onto which to thread the new tail boom. To get the screw in, I had to remove the rear motor. While I had things disassembled to this degree, I decided to re-route my servo & motor wires, and also to cut off some completely unnecessary material from the sides of the bulkhead. I used a cap-head screw around 12mm in length (I didn't measure it precisely before installing it), with the head ground into a square to remove a tiny bit of weight and also to make it easy to grab the head from the side with needle-nosed pliers. With the boom screwed in, I let a couple drops of ultra-thin CA glue travel down the threads to secure the joint.
I cut a tail fin (for looks) out of textured styrene, slid it in the slot I had cut, and secured it with a dab of Shoe Goo. I removed the antenna from the stock foam spool, straightened it, and then wrapped it around the boom with as much space between each wind as reasonably possible, and the end was secured with a short strip of electrical tape.
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Wire Re-Routing (3/10/07)
The new boom assembly, including the heavy steel screw (that I'd like to eventually replace with either nylon or aluminum), weighs just 6 grams, a savings of about 10 grams versus the stock tail & spool. I also shaved another gram by removing the excess bulkhead material. This moved the center of gravity forward a bit, so I wanted to compensate as much as possible without adding forward pitch. There's not much at the front of the craft to remove weight-wise, but the wiring bundle looked like a juicy candidate. Moving that mess away from the circuit board also stood a chance of helping to reduce radio glitching.
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Body Mounting (3/10/07)
I trimmed back a bit of the body just above & behind the clear canopy area to hopefully allow a little more air to pass down over the forward motor. The rear I now squeeze all the way in around the horizontal mounting rod to keep the body close around the airframe, hopefully reducing drag in all directions (though probably by an imperceptible amount.
Gear Mesh (3/10/07)
This is something that I have recommend to everyone, whether or not you want to do any actual modifications to the craft. Check your gear mesh. There should be a slight and equal amount of play between each spur & pinion. I found my upper rotor spur to have nearly no play, while the other just had too little. Gear mesh that is too tight causes motors to run hotter than necessary and reduces your flight time.
Securing the Battery (3/10/07)
One of the well-known small, but nagging issues with this craft is the battery mount. It is completely open at one end, allowing you to slide the battery in, but because there is no latch and nothing but friction to hold the pack in place, the battery tends to shift in flight or on landings, upsetting the center of gravity. I solved this once & for all with a strip of velcro at the back of the battery tray and on the end of each of my packs.
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Flybar Adjustment (3/10/07)
Now this is a modification I don't recommend to just anyone. I wanted to increase the agility & speed of the craft without making fine maneuvering more difficult, so I moved my flybar weights in quite a lot. I flew two packs with this configuration and found the craft to fly more like a CP (collective pitch, traditional style) heli -- more difficult! It was also much faster and more agile as expected. However, since most of my flying is done in fairly confined spaces, I ended up going back to the stock spacing for now.
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