titanx

hi everyone! can anybody clarify the following:

1. meaning / essense of gear ration e.g. 1.3:1.. what is the effect / difference between geared and direct.
2. does a certain radio transmitter have corresponding sets of servo and receivers... or can I use one radio transmitter for different sets of servo and receiver

Thanks in advance.

Glacier Girl

My Feedback: (4)

A gearbox is used when you want to spin a bigger prop than the motor could spin by itself. Direct drive is used in applications where a small prop is driven at high speeds. But there are variants that can do the opposite.
Gearboxes are often used in applications that demand thrust vs speed.
The gear ratio you listed, 1.3:1, is pretty simple, The motor will need to make 1.3 revolutions, for the prop shaft to make one. A gearbox is normally used on a motor with high speed, but low torque, the gearbox allows the motor to spin a big prop by reducing the load on the motor through gearing the output to the prop.
Think of an automobile, low gear will give you a lot of power, but not a lot of speed. Going to a higher gear or higher ratio, starts to drop the power, but increases speed.

As for your radio question, Yes and No.
If the transmitter is on the same frequency as the receiver, it will work, but you will need the proper crystal in the Rx, so it knows which channel to listen to.
If the transmitter and receiver are on different frequencies, won't work, even if proper crystal is installed.
As for servos, if the Rx is set up for 3 wire servos, just about any servo will work. To a point.
But if you have 5 wire servos, like the ones used in ParkZone birds, you have to have a 5 wire servo capable receiver .

titanx

Thanks glacier.

To confirm my understanding:

1. the gears are used to alleviate stress/load from the motor while spinning a larger prop. but would require more torque from the motor. (In airsoft gears are also helpful to release stress/load from motor and battery)

2. for the TX, RX and crystals... I should confirm first TX to RX frequency compatibility.. then work with crystals re: correct channels.. then correct wiring for the servos..


Given the facts on item no. 2, I could therefore stick with one transmitter as long as my planes uses similar frequency, right?

By the way, what is the difference between frequencies such as 27mhz... 72mhz.. does that something to do with effective range?.. Also, can I purchase one 4channel transmitter and use it for say 2, 3 and 4 channels receiver planes? (of course, with consideration to receiver - servo relation as you have explained).

Thanks a lot.

laaf2005

My Feedback: (3)

Ok, before you get off track. Transmitters do have certain recievers they will work with. Not all transmitters will work with all recievers. There is a thing called positive and negative shift. Futaba I believe uses negative shift. Hitec I belive uses positive shift. So a Futaba transmitter will not work with a Hitec reciever. But there are transmitters out there that can switch between shifts, I think only computer transmitters can do that. They are generally more expensive. A normal 4 channel transmitter cannot do this so you need to stick to whatever brand your transmitter is or a brand that uses the same shift. Some reciever manufacturers also make recievers that can detect the transmitters shift. I know this may be a little confusing, the easiest way to remember is that if its not a computer transmitter then it has a certain shift. Futaba and JR use negative shift, Hitec and Airtronics use positive shift. Other brands such as Tower Hobbies, GWS, and Great Planes make recievers that work with both. Servos work with all recievers as long as they have the same number of wires, but they do make some micro servos with micro connectors, but you dont need to worry about that. The best thing to do is when you find something you want to buy post a message on this forum describing the equipment and let someone verifty it will work correctly.

titanx

I already have with me a COX F-4 phanthom which, sad to say only controls the left and right direction (1 channel only). recently I ordered the parkzone decathlon, which is currently in transit. Now I am planning to modify (experiment with) the COX F-4. I will try to place controls for the motor, rudder and elevator using the transmitter of the decathlon.