ELECTRIC PLANES
FOAMY FLYING
By: Bob Peiser and Joe Piccolo, March 2005
A couple of us TRAC members who fly electric powered planes have been asked to assemble a primer for members of TRAC who might want to get “charged up” on the electric flying circuit. Our comments are based on personal experiences and do not reflect an endorsement or recommendation by TRAC or us of any of the practices, web sites, equipment or material. These are intended as basic guidelines as all who get into electric flying will find they make adjustments to the path already trodden.
There are many factors that come into play in flying the electric planes. But, basically, the principal one is whether you fly a BRUSHED or a BRUSHLESS motor. Both can deliver satisfactory flight. The brushed motor is more the slower “Park Flyer” type while the brushless motor can deliver performance closer to that of a fuel powered plane. Flight duration can be anywhere from three minutes to over 12 minutes depending on motor size, battery capacity, type/style of flying etc.
BRUSHED: Give good service and reasonable performance and are a lot less expensive. They are not as powerful as brushless motors and do not turn up the rpm’s, but they can swing a big prop (12x6, 10x407). They do fly the plane at slow speed and can give a 5 to 7 minute flight using a mid-size battery. You can use Nicad, Nickel Metal Hydride (NiMH) or Lithium batteries. Nicad/NiMH batteries run from 3.5 to 8 volts and are heavier. Lithium battery power is best at 7.4-volt level. These motors can fly on the 11.1-volt lithium battery but they tend to burn out quicker using the higher voltage. These are geared motors with varying ratios. Most are made by GWS and take GWS props. APC props are difficult to adapt for use on GWS motors.
BRUSHLESS: These motors come in two types—Geared and Outrunner. The outrunner turns the entire motor to move the prop shaft. Brushless motors are considerably more expensive than brushed motors. Depending on the size of the motor you can swing a large or small propeller (12x6 to a 9x8 or smaller). APC slow fly props are good to use on this type motor. These motors are more powerful than the brushed type but also use up more amps from the battery. They fly best on 11.1-volt Lithium batteries but the 7.4-volt size can also be used.
BRUSHED-BRUSHLESS PRO/CON SUMMARY
|
Motor Type |
Pro |
Con |
|
Brushed |
Less expensive motor and ESC Handle larger props |
Less powerful Likely to burn out on 11.1 volt batteries |
|
Brushless |
More powerful Operate on 7.4 and 11.1 volt batteries, 11.1 preferred |
More expensive motor and ESC |
SPEED CONTROLLER:
both brushed and brushless motors require an ESC (speed
controller) to operate. This acts as the
throttle servo does on a fuel power plane. It also regulates the power to the
receiver and thereon to the servos. NOTE: Brushed motors require a speed controller
that can be used ONLY with brushed motors. Example is the Pixie-20 or the GWS 300.
Likewise, the brushless motors require a speed controller that can ONLY
be used with brushless motors. Example
is the
2 cell Lithium batteries are 7.4 volt while 3 cell are 11.l volt.
They both come in various mah capacities. We have found that 720-mah capacity gives
good results and longer duration can be had with 1500 mah capacity
batteries. Current technology makes
larger mah capacity batteries heavier and while the planes will fly, the extra
weight does impact on performance.
TRANSMITTER: You can use your regular transmitter, as the receivers are crystal controlled. The number of servos you use on the electric plane will be determined by whether you use a 4 channel or a 6 and up channel type transmitter. You can use a “Y” connector for wing servos but this adds weight and encumbrance.
RECEIVER: The least expensive is the GWS receiver in either a 4 or 6 channel configuration. They are not as powerful as a regular receiver but have proven to be capable for electric flight. Since you fly in closer, the range of 600 to 1,000 feet is no problem. There are other mini size receivers available such as Berg, FMA etc. They are much more expensive. The GWS and other receivers are all frequency controlled using crystals.
SERVOS: The basic plane will use three servos. One for the ailerons, one for the rudder and one for the elevator. You can increase to 4 servos and have individual servos for the ailerons. By going to individual servos on the ailerons, you can program in flaperons and elevator/flap mixing. There are several lightweight servos available that do a good job on the planes as far as maneuvering them. Flaperons are handy when landing as they increase the gliding capability of the planes. The foamy's like to sink quickly when the power cuts off or gets low. Some servos available are the Tower (TS-5-S3K), Hitec (H-55) or Light Flight (RCBMS-306 or BATS –4.3).
PROPS: GWS props fit the GWS motors. APC props work fine on brushless motors. GWS motors have a prop nut system. The brushless motors require either a setscrew mechanism or a collet type spinner to hold the prop on. Using the prop saver (rubber band) system with brushless motors has not proven to be successful. The motors throw the props too easily. Experimenting with the props for the type of flying you do is essential. Usually, the higher the pitch, he more amps the prop will make the motor draw.
PLANES: There are many ready to assemble foam planes available. Prices vary. Or you can build your own “foamy” by download plans from an Internet site, borrowing a template from a fellow flyer, or just designing your own plane. The basic cost for a foamy airframe you build yourself runs from $5.00 to around $15.00 – depending on the size and type of foam used.
FOAM MATERIAL: There are two types that work well. Depron (white) is the more expensive one. The other material is Dow Corning Blu-Cor. The depron is easier to work with. Depron can be found at Charlie’s Discount Hobbies in single sheets. The Blu Cor is found at Lowes and comes in packs of 25 sheets.
GLUE: There is special CA glue for use on foam. However, experience has shown that 5 or 30-minute epoxy is the best overall glue for construction or repair.
OTHER MATERIALS NEEDED:
4 mm size carbon fiber tube for wing support
1/16-inch carbon fiber rod for reinforcing/stiffening tail or nose areas. Thin metal pushrod or piano wire can also be used.
Double Sided foam tape to hold ESC, Receiver and servos in place
Velcro type tape to hold battery in place and to facilitate
battery removal for charging/replacement
1/32-inch size Piano wire to use for pushrods
1/16 inch Wheel Collars to use to hold two pieces of pushrod wire to permit easy adjustment to level control surfaces
2-inch wide clear packing or storage tape to use for control surface hinges and repairs to the foam on the plane.
Large size plastic electric tie wraps. These are cut and drilled out for use as control horns. They are also used as nose/bottom skids on fuselages.
3/8-inch square hardwood to be cut in approx. 3-inch lengths to be used for motor mounts.
CHARGER: There are several lithium battery chargers available. Our experience has been with the Triton Charger and that has proven to be satisfactory.
CONNECTORS: You may occasionally need a servo extension or “Y” connector. Other than that, you will need several male and female two-pin connectors. Exception to this is with brushless motors. They come with three connectors. You still need a two pin female connector for the battery hook up to the ESC.
SUMMARY:
Below are some web sites where plans for foamy planes can be found and downloaded as well as the source of supplies for electric flying. This is by no means an all-inclusive list. Your local hobby shop is also a source for much of items needed for electric foamy flying.
Also, here is a sample list of the items needed other than that required to construct the airframe that are known to work well together:
|
Item |
Catalog Number |
Source |
Price |
|
Triton Charger |
TG4112 |
Tower |
129.99 |
|
Triton Thermal Probe |
TG4113 |
Tower |
8.99. |
|
Banana plug/2 pin |
GPMM310 |
Tower |
3.49 |
|
Item |
Catalog Number |
Source |
Price |
|
GWS350C Geared Motor 6.6:1 |
LXHHK8 |
Tower |
16.63 |
|
GWS R6N11/F 6CH Rec |
LXHHR9(Fut) |
Tower |
24.50 |
|
GWS |
LXHHS1** |
Tower |
7.00 |
|
Pixie 20P ESC |
LXGTY9 |
Tower |
33.99 |
|
Female 2 pin connector |
GPMM3107 |
Tower |
2.79 |
|
Male 2 pin connector |
GPMM3106 |
Tower |
2.79 |
|
|
GPMP0810 |
Tower |
27.99 |
|
Servos – Qty 4 |
BMS-306 |
LightFlight |
56.00 |
|
Prop GWS 12X6 – Qty 6 |
LXHHY |
Tower |
12.00 |
|
Total |
|
|
183.69 |
|
Item |
Catalog Number |
Source |
Price |
|
Himax Outrunner
& ESC (Castle Creations |
HC2808-0860 |
LightFlight |
99.95 |
|
GWS R6N11/F 6CH Rec |
LXHHR9(Fut) |
Tower |
24.50 |
|
GWS |
LXHHS1** |
Tower |
7.00 |
|
Female 2 pin connector |
GPMM3107 |
Tower |
2.79 |
|
|
GPMP0811 |
Tower |
31.99 |
|
Servos – Qty 4 |
BMS-306 |
LightFlight |
56.00 |
|
Prop APC 10X4.7 |
LX1684 |
Tower |
2.79 |
|
Total |
|
|
225.02 |
http://www.towerhobbies.com/electric/index.html