Author: Bob Aberle
Edition: Model Aviation - 2004/06
Page Numbers: 48,49,50,51,52,54,56,58,60
,
,
,
,
,
,
,
,

Introduction to Parking Lot Flying - 2004/06

I would suspect that most RC modelers have heard the terms "parking lot flying," "backyard flying," or "schoolyard flying" in the past few years. Some may wonder how these types differ from regular RC flying. They really aren't different when you consider the aircraft involved and the radio control systems that go in them. The primary differences are where the aircraft are flown and the fact that they are basically small models employing modest power levels.

As I proceed through this presentation I'll just refer to parking lot flying, but it will be assumed that I also mean backyard and schoolyard flying. All three types of flying sites are clearly different from a regulation club-sponsored RC flying site. Club fields, as they are generally known, are situated in relatively remote locations where engine noise becomes less of a factor. The open spaces also provide ample opportunity to fly much larger aircraft in a safe manner.

As the name implies, parking lot flying is what we might also call "close-in" flying. It might be on any large parking lot in any populated area. An advantage is that you don't have to travel very far to fly. A shorter distance to the flying site means more opportunities to go flying. Quiet electric power also permits early morning and early evening, calm-weather flying without bothering or upsetting the local population.

Parking lot flying offers you the chance to easily involve your entire family in a sport and hobby that is educational and entertaining.

The Safety Considerations

As with all good things, there can still be disadvantages. With parking lot flying, you must be careful of the surrounding areas. Keep clear of vehicles, houses, and people. To cope with these potential safety problems, parking lot fliers are by necessity small and employ relatively low-power motors.

To be "environmentally friendly," most parking lot-size aircraft are powered by clean and quiet electric motors. However, small-displacement glow-fueled engines can be used successfully, provided that the engine noise doesn't become a factor for those nearby.

Another safety aspect is that "regular size" models and "parking lot-size" models use the same RC channels (or frequencies). This means that one faction could easily interfere with the other if the two types of flying are done in close proximity to one another.

A three-mile separation from control points (location of the transmitters) is generally sufficient to prevent interference. However, even that fact has been subject to much recent debate, and I only mention it as a point of reference.

Because of the possibility of interference, parking lot fliers should be especially aware of local established flying fields. The best way to determine this possibility is to contact a local hobby-shop owner or seek out a local organized RC club and talk to the members.

There is also the chance that a parking lot flyer, if close enough, might interfere with a backyard or schoolyard flyer. With quiet electric motors, it won't always be obvious if someone is flying in the adjacent parking lot (or a private home’s large back yard). Preventing all types of interference would be virtually impossible, so the best solution is to be alert, ask around, and keep your eyes open for other RC fliers.

The Definitions

For some time we have been trying to come up with an adequate and meaningful definition of a "parking lot flyer." Generally, everyone with a relatively small airplane wants to be included.

Common sense dictates that there must be a weight and power limit when it comes to flying in close-in environments. To that end, 16 ounces total model weight seems to be the current acceptable figure. Most of the popular parking lot models average 7–14 ounces.

At 16 ounces you are almost into the Speed 400-size motor. Most of us who use parking lot-size models agree that Speed 400 flying should be done at a regulation flying site such as those maintained by local clubs that are sanctioned (chartered) by AMA.

That being the case, the largest sensible motor that parking lot fliers employ should be Speed 280 or 300 size, which generally runs up to an approximately 30-watt power level. That size includes some of the new, tiny, brushless motors such as the Hacker B-20 series, the AstroFlight 010/020, and others.

The final consideration for a parking lot flyer is its wing loading. The thinking is to limit the wing loading to 8 ounces per square foot of wing area. Take the typical and extremely popular Watt-Age Lite Stik (also known as the GWS Pico Stick); at 238 square inches and 8 ounces average weight, the resulting wing loading works out to 4.8 ounces/square foot. A Sig Manufacturing Jenny has a wing area of 285 square inches and weighs roughly 10 ounces. This biplane’s wing loading is 5 ounces/square foot. These moderate-size and -weight models yield an equally moderate wing loading.

If I were to power the popular Radical RC Verti-Go 3D (a vertical-maneuver "E-3D" design) with a Hacker B-20 brushless motor, the total weight might be 14 ounces. At 280 square inches of wing area, that's a wing loading of 7.2 ounces/square foot, which is close to my suggested limit. Although that model can be quite fast, it can be slowed considerably for its vertical maneuvering.

On the other hand, consider an 80-square-inch model that is powered by a brushless 010 motor and weighs approximately 10 ounces. That works out to 18 ounces/square foot of loading, and that airplane is capable of speeds in excess of 60 mph. That is exactly the kind of airplane I would not like to see flown in a parking lot. Got my drift? I used this example to show why I think the wing-loading limitation is also very important to help categorize a parking lot flyer. If you are used to flying a real "hot" airplane, you may not agree with me on this point.

The Models

Now you know about the safety concerns and have a reasonable definition of a parking lot flyer that takes into consideration weight, size, and power. But what kind of aircraft should the beginner try? As with any kind of model today, be it glow-fueled, electric, gas, etc., there are RTFs, ARFs, those built from kits, and those built from published plans.

There aren't very many in the RTF category, but that will eventually change, I'm sure. The popular RTF that first comes to mind is the Merlin, which Megatech Inc. distributes. The Merlin includes the complete motor and RC system, already installed in the model. You attach the wings, charge the battery (battery and charger are even supplied), and fly it. It is almost at my upper limit of 16 ounces, but at 511 square inches of wing area, the resulting wing loading is still only 4.9 ounces/square foot.

The Merlin will also slow to the point where you can practically walk underneath it as it flies. So if you don't care about building or assembling and only want to learn to fly, this might be the airplane for you.

The most common and popular type of model for parking lot flying is the ARF. These models take on many forms. Some are balsa-wood, built-up structures that are covered for you, and others are made from expanded foam molded parts. In most cases you have to join the wing panels and attach the tail surfaces. Many ARFs come with pre-hinged control surfaces, which can save a lot of time. You usually have to install the electric motor system (motor, battery, and speed controller) and the RC system, including the all-important servos.

Probably the most famous ARF parking lot flyer is the Watt-Age Lite Stik (GWS Pico Stick). It has a foam wing and tail with a stick fuselage. The radio equipment and battery literally just "hang out!" It is inexpensive, easy to assemble, and easy to fly. There is also a larger version called the Slow Stick, which uses the same design and construction and employs a Speed 300-size geared motor.

Although they are not as popular as ARFs, quite a few parking lot-flyer kits are available. Kits give you the added pleasure of building a complete aircraft. Many of the kits now on the market include laser-cut parts that feature true precision. This allows for easy assembly in a minimum amount of time. One of the nicest kits I've assembled is the Bantam Bipe. It is available as a biplane and as a monoplane. With 380 square inches of wing area, a weight of 9.4 ounces, and a wing loading of 5.9 ounces/square foot, the Bantam biplane is a perfect parking lot flyer. The combination of excellent kit engineering and super-detailed assembly instructions make this one of my favorites.

In addition to slow-flying sport models, we are now seeing many so-called vertical-maneuver, "E-3D"-type airplanes. These particular park flyers generally sport the small-size brushless motors. A good such kit is the Radical RC Verti-Go 3D. Another is the Attitude, designed and kitted by Todd Long of Todd's Models Inc.

The last category of models is the kind built using published full-size plans. Construction articles are published regularly in the various model-aircraft magazines. You purchase the plans and then buy the necessary materials. You have to cut out your own parts before you begin the assembly process. I’ve included photos of several of my recently published designs.

Take your pick. Buy it ready to fly or almost ready to fly and do a little assembly work. If you want to enjoy building as well as flying, try a kit. If you want to really "roll your own," try building from plans or from scratch.

There are literally hundreds of model aircraft designed for parking lot flying that can meet any or all of your personal requirements. There are slow models, fast models, aerobatic models, pylon racers, powered sailplanes, RC hand-launched gliders, scale models, semi-scale models — you name it.

Power-system examples

Bantam Bipe power-system components (examples): GWS standard IPS-A motor; SR Batteries seven-cell 150 mAh Ni-Cd battery pack; Jeti JES-050 ESC with a 5-amp current rating; GWS 9 x 4.7 propeller.

Example brushless system: Hacker USA B-20-26S brushless motor with 4:1 planetary gearbox and a Companion Jeti JES 06-3P (6-amp) brushless ESC. This system can handle models weighing 11 to roughly 16 ounces. High efficiency and long operating life do cost more.

Typical precision-made AstroFlight 010 geared brushless motor can generally handle models of roughly 10 ounces total weight. It is small and lightweight.

For standard ferrite-type small motors, a 1/6-ounce Jeti JES-50 5-amp ESC with BEC is an economical choice.

Popular, inexpensive GWS parking lot motors include the LPS series (smallest, N-20-size motor), the IPS series (standard-size similar to a 180), and the EPS series (Speed 300 motor). Most of these small, geared motors are $20 or less.

Castle Creations makes excellent ESCs for standard and brushless motors. Examples: the Pixie-14 (now available in a tiny 20-amp version) and the Pixie-7P (most popular; 7-amp rating and programmable for several cutoff points).

Common battery packs used for park flyers include six-, seven-, and eight-cell NiMH packs and small NiCd packs such as SR Batteries seven-cell 150 mAh. NiMH packs shown in sources range from 280 to 600 mAh.

The Power Systems

The GWS electric motor systems are popular for parking lot flying because there is a wide variety in size and gear reduction ratios offered. These systems are inexpensive, typically $10 to $20. GWS also provides a big variety of orange propellers that complement the gear drives.

One problem associated with the GWS line of small ferrite electric motors is that the shipping wrapper is identified but the motor itself often is not. Many times the wrapper is removed and the motor’s identification (and sometimes its rotation direction) is unknown until you hook it up, so test the motor before final assembly. I recommend that GWS correct this packaging problem.

Balsa Products, Horizon Hobby, and Maxx Products International are primary GWS motor suppliers in the U.S. For parking lot application, the largest motor of interest is GWS's EPS series (Speed 300-size) for 12–16 ounce models. The midrange IPS series (similar to a 180) can fly models from roughly 5 to 12 ounces. The smallest LPS series (N-20-like) is for 3–5 ounce models, the lower end often used for indoor RC.

There is also a variety of small-size brushless motors (roughly 280 power) available from Hacker USA, AstroFlight, Phasor, Mega, and Razor. These brushless motors need a special speed controller. A geared brushless motor and companion ESC can cost between $150 and $200. Brushless motors offer better power-to-weight ratio, higher efficiency, and longer life without brush wear.

The Speed Controllers

Equally important to the electric motor is the electric speed controller (ESC). The ESC takes the place of a throttle servo. A good ESC will provide linear motor speed control from off to full throttle.

Most ESCs include a battery eliminator circuit (BEC) that allows you to share the motor battery with your RC system, meaning only one battery pack is required on the aircraft. Most BECs work with 6–10 NiCd/NiMH cells or two to three Li-Poly cells. Many parking lot fliers use BEC-equipped ESCs to save weight.

Another important parameter is the ESC's maximum continuous current rating. Smaller motors such as the GWS IPS draw approximately 2–2.5 amps and can use a 5-amp rated ESC. Larger GWS EPS (300) motors run 5–6 amps, so an 8–10 amp ESC is more appropriate.

One favorite ESC for parking lot flying is the Castle Creations Pixie-7P; it allows selection of four different voltage cutoff levels from a single unit. Programming takes patience, but the feature is useful. In practice, many models land before the cutoff operates.

Sources for ESCs include Castle Creations, FMA Direct, Hobby Lobby International, Horizon Hobby, Tower Hobbies/Great Planes, and more.

The Batteries

Until recently, the most popular batteries used for parking lot flying were six-, seven-, and eight-cell NiCd or NiMH packs with capacities ranging from 150 mAh up to 600–720 mAh. Recently, Li-Poly battery cells have made significant progress and become popular.

Li-Poly cells require a special charger and have certain safety requirements. For a complete understanding of these batteries, including safety precautions, see "Introduction to Lithium-Polymer Batteries" (May 2004 MA).

Because that article covers Li-Poly in detail, this article deals only with traditional NiCd and NiMH cells. Refer also to MA's "From The Ground Up" series — specifically "Introduction to Electric Power" (July 2003) and "Battery Basics" (October 2003).

You can purchase battery packs and individual cells from companies such as Balsa Products, Batteries America, Dymond Modelsport, Hobby Lobby International, Maxx Products International, New Creations R/C, SR Batteries Inc., Radical RC, and many others.

In general, these battery packs can be selected to provide five- to 10-minute flight times per charge. Use a field fast charger to get in a few flights during one flying session. If you want many flights, purchase several identical battery packs and swap them between flights.

The Battery Chargers

See "Introduction to Electric Power" (July 2003) for detailed information about battery charging. The key item to buy from the start is a peak-detect type charger. One recommended unit is the Global/Watt-Age PF-12 Park Flyer AC/DC Peak Charger; for $49.95 it is an excellent choice. The PF-12 can charge four to 12 NiCd/NiMH cells at selectable currents from 250 to 2000 mA and handles most park-flyer batteries from 150 to roughly 1000 mAh.

There are more expensive chargers with additional features. Sources for peak-detect chargers include AstroFlight, Dymond Modelsport, FMA Direct, Great Planes/Tower Hobbies, MRC, and more.

The RC Systems

Parking lot fliers generally need lighter-weight RC equipment. If a park flyer is supposed to weigh 7 ounces ready to fly, you cannot use a radio system that weighs 8 ounces by itself. Therefore, select RC receivers and servos that are small and extremely light.

For a receiver, dual-conversion circuitry is desirable; it makes for a sensitive and selective unit more immune to outside interference. One commonly used receiver is the FMA Direct M5, which weighs less than 0.4 ounce and is available on 72 MHz channels and six-meter (50 MHz) channels for licensed Amateur Radio Service operators. Other good receivers include the dual-conversion Hitec Electron 6 and several single-conversion receivers such as Berg and JR units.

For servos, you want submicro varieties. One of the smallest is the FMA Direct PS20 at 5.3 grams (0.19 ounce). It is a fully proportional, feedback servo — not a magnetic actuator. Another microservo is the Hitec HS-50 at 5.6 grams (0.20 ounce).

Other small servos are offered by Balsa Products, Dymond Modelsport, GWS, Hobby People, JR/Horizon, Maxx Products, and others. New 1.5-gram servos are coming to market, but expect to pay for that miniaturization.

RC receivers have a characteristic wire antenna roughly 40 inches long exiting the case. Such a long wire trailing from a small aircraft looks awkward. To help, Azzar of E Cubed R/C developed a series of reduced-size receiver antennas. You lose approximately 15% of normal radio range, but the antenna is only about 7 inches long and has become popular with park flyers.

The Connectors

RC systems come with various connectors that mostly interchange between brands. Follow the manufacturer's directions and note each manufacturer's wire color coding.

GWS supplies a two-pin connector on all its motors. Most modelers solder the motor terminals to the ESC for a permanent connection. On the battery side of the ESC you will need a connector; typically you will install that connector yourself.

For larger motors (Speed 300-size, currents upward of 5–7 amps) use Anderson Power Pole (APP) connectors (also known historically as Searns connectors), Deans Ultra connectors, doubled Deans four-pin (two pins per wire), or AstroFlight Zero Loss connectors. If you mix brands, you may need connector adapters.

For 1–3 amp motor currents, the popular connector is the JST (red body). These connectors usually include ~6 inches of red and black wire. Do not exceed the 3-amp rating or they may melt.

Sources of connectors include Balsa Products, Batteries America, Maxx Products International, New Creations R/C, and Radical RC.

The Flying Considerations

Even though you can fly in a parking lot, school yard, or your own back yard (if large enough), you should coordinate with other RC modelers. Setting up an aircraft for the first time and making initial flights is much easier with help. If your model gets away from you, extra help is invaluable. If you get injured near a propeller, having a helper available is important.

Choosing your flying site is another consideration. Don't pick a parking lot that is half filled with cars. Don't pick a school yard when school is in session. Don't fly in your back yard and drive the neighbor's dog crazy. Try to pick safe locations and avoid other known model flying sites. Don't assume it's always the "other guy's" problem.

When you fly at an organized flying site or club field, know what type of frequency control, frequency board, frequency pins, etc., are used and follow those procedures carefully. Also make sure your RC transmitters have identifying channel-number placards attached to their antennas.

Even when flying in a parking lot with a couple of local fliers, determine what frequencies they are using before you turn on your transmitter. Remember it is possible to cause interference a mile away or at your own flying site. Use common sense.

I recommend joining AMA — not only to receive this magazine, but to benefit from its supplemental insurance program.

There are three regular MA columnists involved with electric power and parking lot flyers. Bob Kopski's monthly "RC Electrics" column covers electric power in general and touches on parking lot flying. In alternating months, Dave Robelen's "Micro-Flying" column covers indoor RC and parking lot flying, and Paul Bradley's "Small-Field Flying" column covers parking lot and backyard flying. I highly recommend these columnists.

Also read other magazines such as the Air Age publication Backyard Flyer, which specializes in this type of model aircraft, and Quiet Flyer, which concentrates on electric power and sailplane operations.

About two years ago I wrote the book Getting Started in Backyard Flying. It covers much of what I wrote about in this article but in considerably more detail. It is available from AMA, Tower Hobbies, Balsa Products, and the publisher's Web site at www.rcstore.com/rs/general/books.asp.

There are two important forums operated as free services to electric modelers. They involve daily exchanges of information, test results, and opinions. The primary site for years is the E Zone: www.ezonemag.com/. The other is the Air Age–sponsored Small Flyers Net (SFRC). To subscribe, e-mail [email protected].

In the next chapter I will take you down one more step in size to the world of indoor RC flying. Until then!

Bob Aberle [email protected]

Manufacturers/distributors of parking lot-size models (RTFs, ARFs, kits)

Manufacturers of supporting products and components

Transcribed from original scans by AI. Minor OCR errors may remain.