If you have placed an order within the last month or so, please be patient as i am trying my best to fulfill all orders. This is a small parttime business. I try to have a life beyond it!

____ , , , , ,

Lithium-ion polymer batteries or polymer lithium ion or more commonly lithium polymer batteries and Lipo for short.

Thunder Power lipos are know to be top quality lipo batteries in the RC hobby world, although the price is much higher, but as they say, you get what you pay, quality batteries. I myself rather pay 70% less and purchase from Hong Kong. The longevity of your batteries depends on how hard you push them and how slowly you charge and discharge them. Charging your lipo batteries fast and draining them fast will make them wear out quicker ( sometimes as little as 10 cycles ).

The difference between capacity and voltage:

The capacity of the battery is measured in milli-amp-hours ( mAh ), and it determines how long the battery can run before it’s drained to its minimum safe voltage.

The voltage of lipo batteries is affected by how many cells are in the pack.
3-cell Lipos give out the same voltage regardless of the capacity.

An 800 mAh lipo packs have the same voltage as say a 2200 mAh packs, but the 2200 will last a lot longer if the amperage of the motor is the same. The 2200 is also a lot heavier, which is why its best to use them on bigger planes, and a 800mAh size battery is great for little planes that weigh around 10 to 20 oz such as the little 3D banchee or the Sammy 3D. So basically the mAh of the lipo battery is how long the battery will give out juice, mAh has nothing to do with voltage.

Lipos at full charge have 4.2 volts per cell, so a 3-cell Lipo will have 12.6 volts at full charge, and it will drain safely to about 9.6, maybe a little lower but you do not want to push it. Most ESCs have a LVC (Low-Voltage Cutoff) to prevent you from draining your Lipo too low. I always drain my lipo batteries at 3.6 volts per cell, so 3.6v x 3 cell battery = 10.8v

The capacity of the battery affects how much amperage it can safely deliver. Lipo packs will have an amperage rating given as a function of the capacity, usually around 20C for bigger packs or 30C to 40C for better quality packs. Most packs have the actual max amperage marked on them (See photo below)
20c-lipo-battery
To find the max amprage or max C rating or max C burst rating of a lipo pack, you simply take the capacity of the lipo battery and drop the ‘hours’ unit and multiply by the rating number. So a 2200mAh ( milli-amp-hours ), drop the hours unit, leaves you with 2200 milli-amps, or 2.2 amps. If the rating is 20C, the maximum current that battery can safely deliver is 20×2.2 amps, or 44 amps.

Be very careful that you understand how these units work. Running a battery at less than the rated amperage is required, and running it at much less than the rating will extend the life of the battery. The amperage that your plane will draw is determine by the battery voltage (not capacity), the specification of the motor, and the propeller you choose. The capacity does not determine the amperage you will get, but it does determine if the battery will run safely or not.

One thing i cannot say enough is to purchase a quality lipo battery charger. If you are really into this hobby and use a generic charger, you are putting your self and your home or car in danger of fire, i myself know of 4 people in the field where i fly at who have burned their cars by either not having a good charger or not knowing how lipo batteries work.
Below is a great battery charger that i use myself and have been using it for over 2 years now and i highly recommend it, its easy to use, the price is unbeatable and it will balance your battery and charger your battery with a click of a button.
IMAX B8 Lipo Charger Discharger 1 to 8 Cells
imaxb8 lipo charger

buythisrcitem

  • Comments Off
____ , , , , ,

Plane wing configurations and wing shapes

Aircraft wings are built with many shapes and sizes for desired flight characteristics of an airplane to achieve greater lift, balance or stability in flight.
Here are some different wing types:

delta wing
Thin triangular wing that is especially aerodynamic.
CF-18_Donatello-delta-wing

variable geometry wing
Arrow-shaped wing found on combat aircraft; the angle it forms with the fuselage can be changed in flight.
f14a5-variable geometry wing

tapered wing
Wing that is perpendicular to the fuselage and whose width decreases toward the tip.
0806022_6tapered wing

straight wing
Long wing of consistent width and perpendicular to the fuselage; it is found on low-speed planes such as cargo and light planes.
straight wing plane

swept-back wing
Arrow-shaped wing that is found on jet planes.
747-8-swept-back wing

The figure below also shows the common wing forms and configuration.
airplane-wing-forms-configuration

Wing configurations

The F-14 Tomcat is a supersonic aircraft with a variable geometry wing. This aircraft wing geometry changes according to flying speed by swinging the wings forward and backward.
F-14 Tomcat


Aspect Ratio

Aspect ratio is an indicator of the general performance of an aircraft wing. In aerodynamics, the aspect ratio of a wing is defined as the square of the span divided by the wing area. It is a measure of how long and slender a wing is from tip to tip.
wing Aspect Ratio

For “high” aspect ratio aircraft wing indicates long, narrow wings, whereas a “low” aspect ratio wing indicates short and stubby. Higher aspect ratio has the effect of a higher rate of lift increase, as angle of attack increases, than lower aspect ratio wings.

Respect ratio2

High aspect ratio wing – higher Lift Coefficient
lower stalling angle of attack. eg. Gliders

Low aspect ratio wing – lower Lift Coefficient
high stalling angle of attack… eg. Fighter Jets

However because wings may have varied plan forms it is usual to calculate aspect ratio as:

Aspect ratio = wing span² / wing area = Wing span / Chord length

Dihedral Angle

The purpose of dihedral is to improve the aircraft stability during flight. Dihedral angle is added to the wings for later or rolls stability. When the aircraft encounters a slight roll displacement caused by distribute from air stream or a gust of wind. An aircraft wings with some dihedral will naturally return to its original position.

The front view of this wing shows that the left and right wing do not lie in the same plane but meet at an angle. The aircraft’s wing is inclined upward an angle from root to tip. The angle that the wing makes with the local horizontal is called the dihedral angle.
This is the reason why most commercial airliners such as the 747 or 737 have a dihedral wing for stability.

Anhedral Angle

Highly maneuverable fighter planes, on the other hand do not have dihedral but rather have the wing tips lower than the roots giving the aircraft a high roll rate such as the harrier GR7 jets. A negative dihedral angle is called anhedral.
Harrier jet2

  • Comments Off
« Previous Entries  Next Page »
subscribe to RC hobby

Categories