The Micro Z attached to the Hitec 555 receiver and hanging out of the cockpit of the Alfa FW 190 from Hobby Lobby. The Micro Z keeps the additional 20" of antenna from hanging out of the fuselage. This cuts down on drag but more importantly, makes the s
|Actual antenna wire length:||approx 39.5"|
|Recommended use::||Park flyers, indoor RC and other lightweight aircraft that will remain within 500. ft of the user.|
During the review of the Alfa Model's Focke Wulf from Hobby Lobby, I got to test a new antenna, The Micro Z 72Mhz unit from Dave McCarthy's Lite Fly RC. The benefit of the Micro Z is that its length has been contracted into a three-inch space. The full length of the antenna is still roughly 40" long, however most of the antenna's length is wrapped around a small diameter plastic tube, thereby reducing the useable length of the antenna down to six-inches.
At roughly 6" in length ready to use, the antenna is perfect for slow flyer, indoor and park flyers. In certain cases a slight reduction of radio range was seen, but that's at a distance we usually don't fly park flyers and the like.
Most of us at one time or another have found ourselves with many inches of antenna hanging out of our smaller planes, whether electric, glow or sailplane. Dave Thornburg calculated that an antenna, when allowed to hang down or be strung between the fuselage and the tip of the stab or rudder, adds an additional 15% more drag -- fifteen percent! That's the equivalent of having an additional set of tail feathers on the aircraft. Since many of us fly planes with fuselages shorter than 40", we definitely have to do something with the antenna to keep it from hanging down.
One solution that you absolutely should not do is cut the antenna to a shorter length. This will seriously reduce radio range. A better solution, as shown by the Micro Z antenna, is to coil the antenna around a cylinder of some form. This keeps the antenna the same overall length and keeps the antenna from hanging out of the fuselage or wing. The Micro Z's design is sometimes called a loaded antenna. The typical "rubber ducky" antenna, or the JR (JRPA 155) Base Loaded Transmitter Antenna, utilizes the same design. They wrap either all, or a portion of the antenna's length around a cylinder of some sort, and in the case of the JR antenna, allow an additional length to protrude. The benefits of the design are the same; you don't have a full 40" length hanging out of the transmitter.
The problem with base loaded antennae is that sometimes, in certain atmospheric conditions, transmitter or receiver range is reduced. I've used rubber ducky antennae since they came out and I've never had a problem with range, even though I've flown sailplanes to the edge of my sight. However, there are others that have tried rubber ducky antenna and had range issues.
I received a number of the Micro Z antenna's, many more than I'd use in a year's time, so I kept a few and sent some out to other reviewers. Since the design of the Micro Z is to be used in small, typically light aircraft that will spend 95% of its flying time within roughly 500 feet of the transmitter, that was the type of testing we did. The planes and radios used were all different but used this common receiver antenna, the Micro Z. The aircraft I used was the excellent flying Alfa Focke Wolfe 190 from Hobby Lobby (http://www.hobby-lobby.com/). I cut the original antenna down to about 6" in length and soldered the Micro Z in place of the remaining length. I was able to push the loaded portion of the antenna into the turtle deck area of the fuselage. I used a Hitec FM 3-channel single stick radio, a 555 micro receiver, 2 HS 55 servos, a geared Speed 300 motor with a Jeti speed control and a 2-cell Lithium battery pack.
Test flights were conducted at a local schoolyard that I've flown many times before without radio interference. The 190 flew perfectly! The plane never got more than 500 or so feet from me and control stability was rock solid throughout the entire flight. Changing motors and speed controls to a brushless setup showed no difference in control response or range problems. It was solid all the way.
A couple of the other testers chimed in and reported the following:
"I installed the antenna you sent me onto a GWS Nano receiver that I use in my standard powered GWS Corsair. The antenna is now in the fuse and it looks much better. Because of the size of the plane I don\'t fly it terrible far away from me but I had no control problems flying at my normal field and letting the plane get a maximum of about 800 feet away. I wouldn't/couldn't fly it comfortably any further away then that no matter what the range but with that receiver I wouldn't try any further away then that anyway. Very happy with results. Mike Heer"
"Hello, I received the Micro Z antenna, and installed it on my Berg 5. Range was a little reduced, but not bad. It is perfect for your average indoor or park flyer, and not having to look at an antenna on a scale airplane, or any plane for that matter, is a beautiful thing!"
"The Micro antenna is designed for small model(s) (specially for scale projects) to hide the receiver antenna. It is about 4 inches of wire and required users to cut off all but 6 inches of the original antenna. The Micro antenna weighs in at 1.1 gram. The antenna section the Micro Antenna replaces weighs in at 1.8 gram (Burg rx) and 2.5 grams (Hitec). So the weigh saving is not its main purpose. The antenna design is to eliminate the long antenna hanging in the back of a nice scale project. I tested the antenna in a small (30" span) plane I have. With that size aircraft, I did not notice any lose of range, as I usually do not fly more than 300-400 feet from me. I did not test it in a larger plane."
As you can see, every tester gave it a "thumbs up." While it does take soldering skills to use the product, it's really a simple job. You can also install a single pin connector between the receiver and the Micro Z and have the ability to transfer it from plane to plane. The units weigh practically nothing so they can be installed virtually anywhere in the fuselage or even the wing for that matter. I don't see how you can go wrong with the Micro Z antenna. Get yours today from Litefly RC. Check out his line of electric products and don't forget to tell him you read about it here on RCGroups!
You only talk about the appearance issue and the drag of the original antenna hanging out the fuselage. On my small planes there is also the issue of the mass of the antenna swinging around and causing all kinds of bad dynamic effects. This can really affect the handling of the model.
These small antennas are standard issue for every one of my planes less than 36" span.
GWRO, We review items as we receive them. I'm sure that if we had received them three years ago, we would have loved them then too.
Lance, you are certainly correct that a long antenna can cause unwanted dynamic effects. We are glad to hear that you like the antennae. gv
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