Fly In Your Living Room!
Plantraco’s HFX9000 R/C System
By Len Johnson
Publication: Model Airplane News
Date: October 2005

Have you ever dreamt of flying in your living room? Now you can — with Plantraco’s tiny HFX900 900MHz radio system. This plug-and play system is ready to go, straight out of the box; no soldering is needed to connect the actuators and battery with the tiny 0.9-gram receiver. (And believe it or not, that’s the heavier of Plantraco’s two receivers. The even lighter, 0.38-gram unit can be used to fly Plantraco’s tiny, 7-inch-span Butterfly model. This amazing machine weighs just 4 grams, ready to fly.) I installed the HFX900 system in a TK-inch-span, 7-gram model of my own design.

The system comes with Plantraco’s patentpending, Bahoma magnetic-battery connectors. In this groundbreaking system, two tiny magnets on the receiver are mated with two magnets on the included 90mAh Li-poly battery. The magnets replace not only the battery connectors but also the on/off switch. Just “snap” the batteries into place, and the system is powered up and ready to go; no more pulling on miniscule wires because your pudgy fingers can’t get a grip on the tiny plugs! I’ve lost count of the number of lithium batteries that I’ve pulled the wires off when I tried to unplug the things to recharge them. No longer, though; this battery system is the best thing since sliced bread! Wipe any crud off the magnets before you try to attach them; mine had enough muck on them to prevent a good contact. These tiny magnets are incredibly strong and will pick up anything within range on the workbench. The charger that’s built into the Plantraco transmitter uses the same connection system, so you always have a charged battery ready to go. Yes; the transmitter actually has a built-in lithium charger to top off your cells using its own internal batteries—no wall socket needed. This system is simply bursting with great ideas. Plantraco also offers lithium cells of other capacities that will match the system.

The transmitter The 4-channel, proportional transmitter requires 4 AA batteries and has a host of features in addition to being able to charge your airborne system battery. Two transmitter types are available: one has a spring-centered throttle stick, and the other has a standard, ratchet-type throttle stick. You must choose between them when you order.

The radio doesn’t use any crystals; you use the transmitter stick to choose from three frequencies built into the radio. It also offers V-tail mixing and exponential—very handy if you fly delta wings or are flight-testing a new model. You can trim the controls with a wheel that’s beside each radio stick.

A little door on the left side houses the battery when it’s being charged, and
you can also store a spare battery there. The transmitter doesn’t have an aerial antenna; its high frequency means it can be housed internally (bonus: there’s nothing to break at the wrong moment or to stick in someone’s eye!).

When I tested the system, I achieved 70 yards of ground range. I challenge anyone to spot a small plane that far away! I am sure that the system would exceed the advertised 100 yards in the air. Control was rock-solid, even at the extreme end of the range.

As a bonus, the system comes with a free FMS flight simulator CD and a USB cable so you can connect the transmitter to your laptop. When it’s being used in flight-simulator mode, the transmitter does not radiate, so others can fly when you are practicing on your laptop. A warning here: if you use it with the flight sim, the transmitter will be in simulator mode the next time you turn it on, so remember to switch it to normal radiating mode.

The receiver At 1⁄2-inch square with the thinnest PC board I have ever seen, the receiver is tiny by any standard. The 0.9-gram unit comes wired with three tiny plugs for the battery, motor and servos. It doesn’t have an on/off switch, because the magnetic battery connection takes care of that reliably and without stressing the receiver’s very thin PC board. The instructions advise that you support heavier batteries with a tiny piece of tape, but so far, I have not found that necessary; the system works perfectly as made.

I do think that the receiver’s dipole antenna should be looped through the PC board instead of being attached with a very tiny blob of solder. Half of my antenna fell off, but this was easily remedied with a small soldering iron and a magnifying glass.

The receiver has built-in low-voltage protection: when the Li-poly cell drops below a safe voltage, the receiver cuts the throttle to 60 percent. When this happens, you should land immediately because the receiver will cut the throttle to 30 percent shortly afterward, and few models will fly on 30-percent power. The receiver’s LED will blink a series of flashes to indicate the general state of the battery voltage. This is very useful if the battery isn’t performing well because of its age, or you believe it isn’t charged properly.

Plantraco notes that even lighter receivers are in the works. Mind-boggling!

The actuators are not servos, but they behave like them, so you won’t notice any difference when your model is flying. Those supplied by Plantraco weigh 1.1 grams each and use pushrods. A piece of aluminum wire or thin copper rod will work perfectly, and it’s easy to form the Z-bends needed to connect the pushrod to the actuator arm. I have to confess that although the actuators worked perfectly and had more than enough power, I found the mounting system to be less than user-friendly. To sum up, the HFX900 R/C system is a brilliant offering from Plantraco. From its plug-and-play convenience to its innovative battery attachment, the HFX900 is a giant leap forward for micro RC. Well done!
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