Model Aircraft
Model aircraft are flying or non-flying models of existing or imaginary aircraft, often scaled down versions of full size planes, using materials such as balsa wood, foam and fiberglass. Many designs are possible, from simple gliders, to accurate scale models, some of which can be very large.
Models may be built either as static non-flying models, or as flying models (also known as aeromodelling). Static model aircraftConstruction techniques for the two are usually very different.
Models may be built either as static non-flying models, or as flying models (also known as aeromodelling). Static model aircraftConstruction techniques for the two are usually very different.
Static model aircraft
Static model aircraft (i.e those not intended to fly) are scale models are built using plastic, wood, metal or paper. Some static models are scaled for use in wind tunnels, where the data acquired is use
d to aid the design of full scale aircraft.
Collectors can buy models that have already been built and painted, models that require construction, painting and gluing, or models that have been painted but need to be snapped together. Snap models require minimal construction and are becoming increasingly popular.
d to aid the design of full scale aircraft.Collectors can buy models that have already been built and painted, models that require construction, painting and gluing, or models that have been painted but need to be snapped together. Snap models require minimal construction and are becoming increasingly popular.
Promotional Use
Most of the world's airlines allow their fleet aircraft to be modeled as a form of publicity.[1] In the early days, airlines would order large models of their aircraft and supply them to travel agencies as a promotional item. These models are the most prized collectibles
Manufacturers
Manufacturers of static model kits include Tamiya, Revell Germany, Trumpeter (company), Schuco, Hasegawa, Czechmaster, MPM, Special Hobby, Academy, Hobbycraft, Dragon/DML, Italeri, Minicraft, Fujimi, and Testors. Other companies are Monogram, Revell USA, OzMods Australia and Airfix.
Scale
In static models, the most popular scale is 1:72, followed closely by 1:48. 1:144 is popular for civil airliners, and there is a growing range of military subjects. [2] More detailed models are available at 1:32 and 1:24. Some manufacturers introduced 1:50 scale and 1:30 scale. Japan offers 1:100. The French firm Heller SA is the only manufacturer to offer models in the scale of 1:125. Herpa and others produce promotional models for airlines in scales including 1:200, 1:400, 1:500, 1:600, 1:1000 and more. A few First World War aircraft were offered at 1:28 by Aurora.
Other less popular scales are 1:64, 1:96, and 1:128; however, old molds are often revived in these scales. Many older plastic models, such as those built by Revell do not conform to any established scale. They are sized to fit inside standard sized boxes. These kits are often called "box-scale" and are often reissued in their original, unusual scales.[3] Some helicopters used to be offered in 1:32 scale, similar to some fixed-wing aircraft models. The trend is to issue helicopters in 1:35 scale, similar to most land vehicle models.
Other less popular scales are 1:64, 1:96, and 1:128; however, old molds are often revived in these scales. Many older plastic models, such as those built by Revell do not conform to any established scale. They are sized to fit inside standard sized boxes. These kits are often called "box-scale" and are often reissued in their original, unusual scales.[3] Some helicopters used to be offered in 1:32 scale, similar to some fixed-wing aircraft models. The trend is to issue helicopters in 1:35 scale, similar to most land vehicle models.
Media
The most common form of manufacture for kits is injection molded polystyrene plastic, using carbon steel molds. This takes place mostly in China, the Philippines, South Korea, and Eastern Europe. Injection molding allows a high degree of precision and automation not found in other manufacturing processes. Smaller and cheaper runs can be done with cast copper molds, and some companies do even smaller runs using cast resin molds, but the quality and precision is of a lower standard than carbon steel.
The next most common form of manufacture is cast resin, using silicone rubber molds placed in vacuum chambers to reduce the incidence of bubbles in the castings. This form of manufacture is labor intensive and involves a degree of waste because the resin attacks the silicone and the molds can only be used about 20-30 times before a new mold needs to be made. The flexibility of the mold does allow shapes and undercuts not possible with any other manufacturing method. This sort of manufacture is reserved for unusual or esoteric subjects in relatively small production runs, and are consequently far more expensive than injection molded plastic kits.
Vacuum-formed polystyrene kits are still being made, buta greater amount of effort is required by the consumer to produce an acceptable model compared to the aforementioned methods. There is a handful of photo etched metal kits which allow a high level of detail but can be laborious to assemble. [4] [5] Specialized kits cast in resin are available from companies such as Anigrand, Collect Aire, CMK, and Unicraft.
Scale models can be made from heavy paper or card stock. [6] Card models are also distributed through the internet, and several are offered this way for free. Card model kits are not limited to just aircraft, with kits being available for all types of vehicles, buildings, computers, firearms and animals. Ready-made models (desk-top models) include those produced in fibreglass for travel agents and aircraft manufacturers, as well as collectors models made from die-cast metal and plastic. [7]. Snap Fit plastic plane models are manufactured by Wooster, Long Prosper, and Flight Miniatures
The next most common form of manufacture is cast resin, using silicone rubber molds placed in vacuum chambers to reduce the incidence of bubbles in the castings. This form of manufacture is labor intensive and involves a degree of waste because the resin attacks the silicone and the molds can only be used about 20-30 times before a new mold needs to be made. The flexibility of the mold does allow shapes and undercuts not possible with any other manufacturing method. This sort of manufacture is reserved for unusual or esoteric subjects in relatively small production runs, and are consequently far more expensive than injection molded plastic kits.
Vacuum-formed polystyrene kits are still being made, buta greater amount of effort is required by the consumer to produce an acceptable model compared to the aforementioned methods. There is a handful of photo etched metal kits which allow a high level of detail but can be laborious to assemble. [4] [5] Specialized kits cast in resin are available from companies such as Anigrand, Collect Aire, CMK, and Unicraft.
Scale models can be made from heavy paper or card stock. [6] Card models are also distributed through the internet, and several are offered this way for free. Card model kits are not limited to just aircraft, with kits being available for all types of vehicles, buildings, computers, firearms and animals. Ready-made models (desk-top models) include those produced in fibreglass for travel agents and aircraft manufacturers, as well as collectors models made from die-cast metal and plastic. [7]. Snap Fit plastic plane models are manufactured by Wooster, Long Prosper, and Flight Miniatures
Flying model aircraft
Main article: Radio-controlled aircraft
Flying models are usually what is meant by the term aeromodelling. Most flying model aircraft can be placed in one of three groups:
Free flight (F/F) model aircraft fly without any attachment to the ground.This type of model pre-dates the efforts of the Wright Brothers [1] and other pioneers.
Control line (C/L) model aircraft use cables (usually two) leading from the wing to the pilot. A variation of this system is the Round-the-pole flying (RTP) model.
Radio-controlled aircraft have a transmitter operated by the pilot on the ground, sending signals to a receiver in the craft.
Some flying models resemble scaled down versions of piloted aircraft, while others are built with no intention of looking like piloted aircraft. There are also models of birds and flying dinosaurs. One company, Flying ThingZ of Stroudsburg, Pennsylvania, makes unusual offerings, produced from laser-cut corrugated plastic include a witch on a broomstick, a flying M1A2 Abrams tank, a flying race car and even a 2/3-scale flying lawnmower
Construction
The construction of flying models is very different from most static models. Flying models borrow construction techniques from (usually vintage) full-sized aircraft (although models rarely use metal structures.) These might consist of forming the frame of the model using thin strips of light wood such as balsa, then covering it with fabric and subsequently doping the fabric to form a light and sturdy frame which is also airtight. For very light models, very thin paper can be substituted for fabric. Heat-curing plastic films ("heat shrink covering" or "solarfilm") can be ironed on — a hand-held iron causes the film to shrink and adhere to the frame. A hair dryer can also be used.
Other model construction techniques consist of using formers and longerons for the fuselage, and spars and ribs for the wings and tail surfaces. More robust designs may use solid sheets of wood to form these instead, or might employ a composite wing consisting of an expanded polystyrene core laminated with a surface veneer of wood, often obechi, which protects the core and provides strength. Such designs tend to be heavier than an equivalent sized model built using the traditional method, and would be much more likely to be found in a power model than a glider.
The lightest models are suitable for indoor flight, in a windless environment. Some of these are made by bringing frames of balsa wood and carbon fiber up through water to pick up thin plastic films, similar to rainbow colored oil films. The advent of "foamies," or craft injection-molded from lightweight foam and sometimes reinforced with carbon fiber, have made indoor flight more accessible to hobbyists. Many come ready-to-fly, requiring little more than attachment of the wing and landing gear. See: ParkZone Slo-V.
Flying models can be built from scratch using published plans, or assembled from kits. Plans are intended for the more experienced modeller, since all parts must be sourced separately. The kit contains most of the raw material for an unassembled plane, a set of assembly instructions, and a few spare parts to allow for builder error. Assembling a model from plans or a kit can be very labour-intensive. In order to complete the construction of a model, the builder assembles the frame, covers it, and aligns the control surfaces.
ParkZone P-51D Mustang
To increase the hobby's accessibility to the inexperienced, vendors of model aircraft have introduced Almost Ready to Fly (ARF) designs. Compared to a traditional kit design, an ARF design reduces the amount of time, skill, and tooling required for assembly. The average ARF aircraft can be built with less than 4 hours of labor, versus 10-20+ for a traditional kit aircraft. More recently, Ready To Fly (RTF) radio control aircraft have all but eliminated assembly time (at the expense of the model's configuration options.) Among traditional hobbyist builders, RTF models are a point of controversy, as many consider model assembly as integral to the hobby. Brands associated with these types of aircraft include Great Planes, Hobbico, Carl Goldberg Products, Lanier RC, E-Flite, Hangar 9, GWS, HobbyZone and ParkZone Tower Hobbies.
Other model construction techniques consist of using formers and longerons for the fuselage, and spars and ribs for the wings and tail surfaces. More robust designs may use solid sheets of wood to form these instead, or might employ a composite wing consisting of an expanded polystyrene core laminated with a surface veneer of wood, often obechi, which protects the core and provides strength. Such designs tend to be heavier than an equivalent sized model built using the traditional method, and would be much more likely to be found in a power model than a glider.
The lightest models are suitable for indoor flight, in a windless environment. Some of these are made by bringing frames of balsa wood and carbon fiber up through water to pick up thin plastic films, similar to rainbow colored oil films. The advent of "foamies," or craft injection-molded from lightweight foam and sometimes reinforced with carbon fiber, have made indoor flight more accessible to hobbyists. Many come ready-to-fly, requiring little more than attachment of the wing and landing gear. See: ParkZone Slo-V.
Flying models can be built from scratch using published plans, or assembled from kits. Plans are intended for the more experienced modeller, since all parts must be sourced separately. The kit contains most of the raw material for an unassembled plane, a set of assembly instructions, and a few spare parts to allow for builder error. Assembling a model from plans or a kit can be very labour-intensive. In order to complete the construction of a model, the builder assembles the frame, covers it, and aligns the control surfaces.
ParkZone P-51D Mustang
To increase the hobby's accessibility to the inexperienced, vendors of model aircraft have introduced Almost Ready to Fly (ARF) designs. Compared to a traditional kit design, an ARF design reduces the amount of time, skill, and tooling required for assembly. The average ARF aircraft can be built with less than 4 hours of labor, versus 10-20+ for a traditional kit aircraft. More recently, Ready To Fly (RTF) radio control aircraft have all but eliminated assembly time (at the expense of the model's configuration options.) Among traditional hobbyist builders, RTF models are a point of controversy, as many consider model assembly as integral to the hobby. Brands associated with these types of aircraft include Great Planes, Hobbico, Carl Goldberg Products, Lanier RC, E-Flite, Hangar 9, GWS, HobbyZone and ParkZone Tower Hobbies.
Gliders
Main article: radio-controlled glider
Gliders are aircraft with no attached powerplant. Model gliders are usually hand-launched or catapult-launched (using an elastic bungee.) The newer "discus" style of wingtip handlaunching has largely supplanted the earlier "javelin" type of launch. Other launch methods include ground based power winches, hand-towing, and towing aloft using a second powered aircraft. As gliders are unpowered, flight must be sustained through exploitation of the natural wind in the environment. A hill or slope will often produce updrafts of air which will sustain the flight of a glider. This is called slope soaring, and when piloted skillfully, radio controlled gliders can remain airborne for as long as the updraft remains. Another means of attaining height in a glider is exploitation of thermals, w
hich are bubbles or columns of warm rising air created by hot spots on the ground. As with a powered aircraft, lift is obtained by the action of the wings as the aircraft moves through the air, but in a glider, height can only be gained by flying through air that is rising faster than the aircraft is sinking relative to the airflow.Sailplanes are flown using available thermal lift. As thermals can only be indirectly observed through the reaction of the aircraft to the invisible rising air currents, pilots find sailplane flying challenging and rewarding.
Hang gliders come in two large categories: hang glider and paraglider. The default use of the term is for the stiffened-wing sort; the paraglider is fully flexible winged.
Walkalong gliders are light weight model airplanes flown in the ridge lift produced by the pilot following in close proximity. In other words, the glider is slope soaring in the updraft of the moving pilot.
Power sources
Powered models contain an onboard powerplant to propel the aircraft through the air. The model is usually powered by an electric motor or small piston engine, but other types of propulsion include rockets, small turbines, pulsejets, compressed gas engines and twisted rubber bands.
Old and cold
An old method of powering free flight models is Alphonse Pénaud's elastic motor, essentially a long rubber band that is wound up prior to flight. It is the most widely used powerplant for model aircraft, found on everything from children's toys to serious competition models. The elastic motor offers extreme simplicity and survivability, but suffers from limited running time, an exponential reduction of thrust over the motor's operational cycle, and it places substantial stress on the fuselage. Even so, a competitive model can achieve flights of nearly 1 hour. http://www.indoornews.com/indoorrecords/record_list.php
Stored compressed gas (CO2), similar to filling a balloon and then releasing it, also powers simple models.
A more sophisticated use of compressed CO2 is to power a piston expansion engine, which can turn a large, high pitch prop. These engines can incorporate speed controls and multiple cylinders, and are capable of powering lightweight scale radio control aircraft. Gasparin and Modella are two recent makers of CO2 engines. CO2, like rubber, is known as "cold" power because it becomes cooler when running, rather than hotter as combustion engines and batteries do.
Steam, which is even older than rubber power, and like rubber, contributed much to aviation history, is now rarely used. In 1848, John Stringfellow flew a steam-powered model, in Chard, Somerset, England. Hiram Stevens Maxim later showed that steam can even lift a man into the air. Samuel Pierpont Langley built steam as well as internal combustion models that made long flights.)
Baronet Sir George Cayley built, and perhaps flew, internal and external combustion gunpowder-fueled model aircraft engines in 1807, 1819 and 1850. These had no crank, working ornithopter-like flappers instead of a propeller. He speculated that the fuel might be too dangerous for manned aircraft.
Monitoring of Model Aircraft Performance
RC Power System Monitor
The increased complexity of model aircraft power systems has created the need for tools to measure model performance, both during ground testing and in-flight.
As of 2008, the popularity of lithium polymer (LiPo) based electric power systems increased the need for this monitoring, due to the relative fragility of LiPo batteries. Several small and low cost in flight monitors and bench meters designed specifically for RC are available in 2008. One example is pictured at right.
RC Power System Monitor
The increased complexity of model aircraft power systems has created the need for tools to measure model performance, both during ground testing and in-flight.
As of 2008, the popularity of lithium polymer (LiPo) based electric power systems increased the need for this monitoring, due to the relative fragility of LiPo batteries. Several small and low cost in flight monitors and bench meters designed specifically for RC are available in 2008. One example is pictured at right.
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