Choosing Your Aircraft
A wide variety of aircraft types, styles and platforms exist; moreover, the materials of which they are made and the level of fabrication “out of the box” is highly variable. The author offers advice that will help you make the right choice.
1 1
1 1
W
e now have a good understanding of the electric power system and the RC system, so the next logical step is to talk about the kinds of model aircraft available. Years ago, model aviation was considered strictly a hobby. The hobby included first building the model and then flying it. In the early days, the primary interest was in free flight and control line models. By the early ’50s we began to see the introduction of radio control (RC) models. As the years passed we saw breakthroughs in construction materials with the development of iron-on coverings and cyanoacrylate (CA) adhesives and cements that cure in a matter of seconds. These advances made building and finishing a model aircraft easier and less time consuming.
ARF AND RTF MODELS
you can buy an RTF model and simply fly, which is what we call the “sport” aspect of model aviation.
IF YOU ARE A NOVICE
Which is best for you? If you a beginner getting involved with model aviation for the very first time, my suggestion is to first experience the thrill of flying. Don’t let yourself get sidetracked by trying to learn basic model-building skills. Get an ARF or RTF model and get out to the flying field as soon as possible. I also recommend that you try a parking-lot model (the 8- to 14-ounce
These and other innovations in model-building technology led to the current popularity of the almost-ready-to-fly (ARF) and ready-to-fly (RTF) models. Today, it is possible to buy a model that is not only fully assembled, but has both the motor system and the RC systems installed and ready to go. All you need to do is to charge the battery and fly. Today’s model aviation hobby offers many possibilities. You can choose to build a model from a kit or, perhaps, scratch-build an entire model from plans. You can finish the assembly of an ARF model, or, if you are not interested in building,
Left: my 21⁄2-year-old grandson, Hayden Parkes, holds my replica Profile Powerhouse, an 80-squareinch free-flight design from the ’50s. I converted it to indoor electric flying. The article appears in the January 2001 issue of RC MicroFlight.
Lil Hornet designed by Merril Brady at MM Glider Tech and sold through David Thacker at Radical R/C Inc. The model has a 232square-inch wing and weighs 9 to 10 ounces, putting it in the parking-lot category. Battery is a 7-cell 720mAh NiMH.
category) for that first model. There are many ARF kits now offered in this category, and models of this size are good training planes. Micro indoor-type models should be put off until you learn the basics of flight.
IF YOU ARE AN EXPERIENCED RC PILOT
Right: on the very light side of things is this ultramicro model built by noted Canadian scale modeler, Jack McGillivray. It is a 920 Moto-Aviette Farman, weighing just 1.2 ounce ready-to-fly. It has an 88square-inch wing area and is powered by 3 50mAh NiCd cells.
So far I have addressed the needs of the beginner. But what if you are an experienced glow-fuel pilot who wants to enter the world of micro flight? Since you likely have the necessary building skills, you might want to consider building a kit or building from published plans. You still will have to learn some of the tricks of electric-powered flight (e.g., battery charging), but that will come with time. Basic flying skills gained from fuel models can easily be converted to skills used with micro electric-powered planes. Regardless of your modeling background, you
82
CHOOSING YOUR AIRCRAFT
Fred Marks, President of FMA Direct, with an Aeronca C-3 lookalike design. This model weighs 6 ounces. Motor is a GWS operating on a 7-cell 250mAh Ni-Cd battery. Area is 260 sq. in. with a wing loading of only 3.3 oz. /sq. ft. Included in the 6 ounces is one of Fred’s new Quantum-6 dual conversion micro receivers. Another popular indoor and parking-lot flyer (in calm wind conditions) is Dan Kreigh’s MINI-IFO. It weighs only 4 ounces, with 320 sq. in. of area and a wing loading of only 1.8 oz./sq. ft. Powered by a D-1717 geared 1.8:1 on 10 50mAh Ni-Cd cells. A very agile performer, it can literally turn on a dime. A great, fun plane—perfect for the backyard as well.
good scales are available for less than $100 from major stationery suppliers, such as Staples, OfficeMax and Office Depot. The scale should be used often and will be very useful in determining the correct choice of materials and components.
Knowing the weight of your models and the individual components is absolutely essential to micro flying. This Pelouze digital scale, purchased at Staples for about $80, does a good job. It is capable of measuring weights of up to 80 ounces with an accuracy of within 0.1 ounce. It will also read up to 2,000 grams with an accuracy of within 2 grams. In this example, the scale is weighing a GWS R-4P micro receiver and two Hitec RCD HS-50 sub-microservos. Total weight is 0.7 ounce.
ADHESIVES & COVERINGS
will need to keep certain things in mind when building and flying small electric-powered models. Weight is of primary importance, as is wing loading. If you have the wing loading too high, the model is not going to get off the ground. Since weight is so important, it is a good idea to buy an accurate digital readout scale at the onset. Several
When constructing or assembling your models, be sure to use the proper cement for the application. Basic CA cement in thick and thin viscosities is used for wood framework assembly. High-stress areas (e.g., wing-panel joining, motor and landinggear mounting) need a 5-minute epoxy. Caution should be taken with models constructed of foam material, since many CA cements will melt the foam. Always test for that possibility using scrap pieces of foam. Lightweight iron-on covering material in either opaque or transparent colors
For those who like to build from plans is this 2.6-ounce model, the Pepper, designed by Dave Robelen. This is in the sub-micro category. It uses a DC 5-2.4 coreless motor on 4.2:1 gearing and a 7-cell 50mAh Ni-Cd battery. Servos are the WES-Technik LS-2.4 linear types. Also a marvelous indoor or backyard flyer.
Falcon/RCS Technik scale SE5a, built by Stew Meyers of Washington, DC. Model weighs only 3.1 ounces ready-to-fly. Wing area is 160 sq. in., and the wing loading is 2.8 oz./sq. ft. Photo taken by Bob Aberle while attending the Indoor Fly at the National Building Museum in Washington, DC.
83
1 1
Hitec's Sky Scooter is a 2- or 3-channel aileron/elevator model for outdoor flying. The 32-inch span plane weighs 16.8 or 18.5 ounces depending on whether you are flying the lighter 2channel version (300mAh Ni-Cd battery) or Pro 3-channel version (600mAh Ni-Cd pack) with throttle. It comes with transmitter and the receiver and servos are factory-installed. Wing loading for the Pro version is 9.65 oz. per sq. ft.
The Dumas Aircraft Kestral weighs only 5.5 ounces with a 34-inch wingspan.
is used primarily for the parking-lot flyers. Lightweight tissue covering such as Litespan is preferred for the micro indoor models. The exact techniques for covering small models can be found in several how-to articles. See, for example, Dave Robelen’s article in the February 2001 issue of Model Airplane News, pages 80 to 82. Also, several of the large mail-order houses offer videos
concerning all aspects of model-building techniques. I refer you to the websites for Tower Hobbies, Horizon Hobby Inc., Hobby People, Hobby Lobby Intl. and Northeast Sailplane Products (see the source guide for further information).
TECH TIP
CHOOSING AN AIRFOIL
Airfoil choices are also important. Parking-lot or micro indoor flyers perform better with higher-chambered airfoils that permit slower flying speeds. Most of the airfoils will have been pre-selected for you by the kit designer, but you should learn which airfoils will offer the best slow-flying performance. The website, http://digilander.iol.it/neon1/profili.html, developed by Stefano Duranti of Italy called Profili, will give you good information, and offers free airfoil-drawing software that will run on Windows 95 and later Windows operating systems. Some excellent high-chamber airfoils can be found at this website (e.g., Benedek BE6356B, used successfully by micro flier, Dave Robelen). This website will be very helpful if you decide to design your own models.
The GYMFLYR was designed by Carl Martin (the prop man!) and is being sold through Anything R/C. It has a 264-square-inch wing area, weighs 4.8 ounces, and the wing loading is 2.6 ounces per square foot. The motor is a D1717 geared 11.8:1 using a 9.5-inch diameter ARC-1 prop running on a Rayovac 9V NiMH battery. The deep underchambered airfoil makes this a true slow flyer, perfect for indoor flying or outdoor flying in dead calm conditions.
84