Plantraco HFX900 Deluxe Starter Set
By: Dave Robelen
Publication: RC Micro World Online Magazine – www.cloud9rc.com
Date: 7/1/2005

When I was asked to do a functional review of this radical new system, I had a few misgivings. It has been my policy to be rather frank in reviews, and where I find problems or faults to call them out, along with the “good stuff”. With so much new in this system, I had concerns that my review might not be as flattering as I would like. As it turned out, I was mistaken, and I will try and do justice to this excellent new offering to the micro community.

Bob Aberle did a fine job of describing the various components of the system, so where there are questions of that nature, I will refer you to his article in the June issue. Meanwhile, there is much to see on the Plantraco website, http://www.plantraco.com/ .

The transmitter is much smaller than customary, and without an external antenna, it took a few moments to adapt to the new feel of it. Shortly, it was evident that this was a transmitter that was a fine match for my micro size models. There are thumb wheels for each trim axis, and while they work fine when you can concentrate on them, I would have preferred levers that I could move more easily in flight. This is a very small thing, and probably personal.

The transmitter is powered with four AA Pencell batteries, and I had concerns about the operating life of these cells that were used to power the transmitter in operation, as well as charge the model battery. These concerns melted away after a lengthy period of activity flying and charging, and the original battery set still had plenty of pep. It appears that it would be reasonable to expect about 20 charges from the batteries, and with 12- 15 minute flight times to a charge, that equals a lot of flying. Case closed.

One of the features of this system is the ability to perform V tail or Elevon mixing, so I decided to build and fly a couple of models using this slightly less conventional control mode. With an all up system weight of 9.1 grams for the airborne parts, I felt I should keep my model structure light to achieve peppy flight from the pager motor drive. As it turned out, 15 to 20 grams is a reasonable range for the final weight, with wing areas ranging from 40 sq. in. to 70 sq. in. It would be entirely possible to build a 13” span Peanut scale model using this system, but I would make sure the wing area was reasonable to keep the wing loading low.

My first choice for a test model was a variation of Gordon Johnson’s neat little Quick Junior. The original model has a conventional tail, and the wings were trimmed from blanks cut by Gary Jones. Since one of my goals was to use the V tail mixing, I modified the tail assembly to this configuration. Meanwhile, I chose to cut my own wingpanels, which have a Benedeck airfoil.

The prop drive is designated the GB-03. The furnished propeller, a 100 mm dia. X 80 mm pitch, is extremely light, and very well designed. The low friction of the drive assembly is illustrated by the fact that it windmills with power off at the low glide speed of my model.

In flight, the equipment handled the model really well, with smooth proportional control at all times. With an all up weight of 15 grams, the little drive could manage a steady climb of at least 15 deg., and had enough pep for loops. The cruise power is at about 50% throttle stick, and the flight times in still air were typically 15 minutes.

In order to achieve smooth control with small magnetic actuators, a really free linkage and hinge system is a must. The picture of the tail of my model shows where I glued in short lengths of thin rubber strand as hinges, being careful to keep the epoxy well away from the flexing area. This flight testing should have satisfied me, since I had flown the little bird out to the limits of vision with full control, and logged well over an hour’s flight time, but I wanted to challenge the system a bit more yet.

To really bring out the potential capability of the tiny equipment and actuators, I chose to build a flying wing with elevon control. A neutrally stable model of this type would certainly require smooth, proportional control at all times to get reasonable results. This being my first effort at designing a flying wing, things did not go easily at first. I was grateful for the ability to trim new parts from the insulation foam as I went through several variations of design. The model shown in the next two pictures was the end result of all this activity.

It is worth mentioning that the Plantraco flight pack is rugged enough to have continued to operate after a good bit of being thumped around during the development cycle. The principal difference in this model’s setup is putting the drive in the front with an extension shaft to the prop in the rear. This solved all sorts of balance issues with such light equipment. As far as the flying went, the final configuration flies and handles really well, with completely smooth control at all times. Largely due to the clean design and semi-symetrical airfoils, the flying wing is right at home on a breezy day. The all up weight of this one is 17.5 grams, and the wing area is about 65 sq. in. The little drive gives it a healthy rate of climb, and it loops with ease. Cruise power is about 60% of the throttle stick.

The one feature of the system I have not yet tried is the included flight simulator. It seems that my antiquated system with Win 98 is not supported by this particular version. The word from other users is that it works fine, and can be very handy with the included micro model in the file. As far as the transmitter and flight system that I have used extensively, I can highly recommend this to any one that would like to take advantage of the multi channel 900 mhz frequencies, with some really well made equipment. I have found the staff at Plantraco very supportive, and well motivated to see their new product do well for the modelers.
- RC Micro World, July 2005