fowlmood77

I (like a few others I have seen recently here) am attempting to build a 48" woody with a Homelite engine. After lurking in a few sites and learning as much as I can, I still have questions. 1-What are the differences between the AM and FM controllers? 2-What kind of torque do I need to be looking for for the steering and throttle servos? Will a basic servo work for the throttle and a high torque work for steering? I am sure I will have more questions as this build goes on and I believe I am in good hands here. Yes I am a newbie

Flabum

The difference between AM and FM is price and signal reliability. Am is cheaper, but the FM has a clearer, more reliable signal.

A standard servo will be fine for the throttle, a futaba S3303 or similar will work. The steering servo should b a heavy duty servo preferably with ball bearings and metal gears as well as be high torque for not only ability but logevity. I reccomend a 1/4 scale servo such as a Futaba 5301 or similar, if room does not allow such a big servo, then a Futaba 3305 at 6 volts will do. The 3305 is half the torque of the 5301, you will be putting far less stress on the 1/4 servo so it will last longer. You will need a y-connector to hook the steering servo straight to the battery.

martno1fan

hi your best going with fm than am as for servos you will need a normal one for throttle and a high torque one for the rudder you can use a 1/4 servo for the rudder or as i did use a normal size high torque one.you will need arround 12 kg of torque or more wont hurt mines actually 15 kg ,you will also need a 6 volt pack to power them through your rx.also make sure the servo has metal gears unlike some cheap ones. seems flabum beat me to it lol but same apllies,although i have my doubts the y harness actually works any better than running the battery to the rx.i know some say it does but i dont see how it could to be honest?.maybe someone can explain to me how using a y harness makes any diff to the voltage?.ive used both ways and havent seen any diff between to two ways to be honest.

patriktegelberg

I am sorry I can not resist to once again show my radio box. Take no notice, this is about fowlmoods radio not mine. This box is not long term tested and I am certifiable nuts.

martno1fan

Naa your not nuts Pat just missunderstood lol

Flabum

Mart, using a y-harness on the steering servo does two things:

1) It take the amperage of the servo direct from the battery rather than passing it through the reciever.

2) It prevents voltage drop in the radio due to the higher amperage the servo draws.

martno1fan

hi mate i dont get that how does that work both the servo and battery are plugged to the harness then the harness to the rx how does the power go direct to the servo surely the power goes to the rx first i just dont get it.

Flabum

I hate hi-jacking threads

the y-harness has the positive and negative in it. You plug one end of the y to the servo, one to the radio in the servo jack and the last to the battery/switch. This gives you a direct battery hookup to the servo thereby making all the amperage for the servo go thru the y-harness rather than going thru the reciever. The reciever recieves it's power thru the y-harness hooked up to the servo jack on the reciever.

MrMikeG

Flabum is right, look at your receiver and see how small the wiring is, you wouldn't use that small of wiring on your battery pack so how do you think it is going to get to the servo? Y connector all the way for me! I'm going to wire my switch inline in the Y connector so there are fewer connections

patriktegelberg

Mythical, thise Y-thingies no? I saw I voltage drop on my spy as I was feeling with my fingers if the mini would do. I naturally tried a Y-harness but no discernable difference. I have also asked myself and others about this but have yet to find an answer to believe. Any anser I believe will likely involve a BEC circuit.

patriktegelberg

Also the harness did not quite fit into the box. [&:]

martno1fan

i am with patrik on this one this doesnt add up to me at all!! i know many people on this site who never use y harnesses and have no problems at all ,simply connecting to a y harness cannot do what you suggest i am sure .not wishing to start an argument here just trying to find some answers but flabum you say you hook one end to the batt one to the servo then the other to the rx ,how does the battery go direct to the servo the signal(power) still has to go through the rx first i dont see how it goes direct to the servo.sorry if ive hyjacked the thread but i still think its relevent.ive seen no evidence to show using a y harness works as you suggested.

pete_486

AHHHHHHHHHHHHHHHHH MART IT WORKS

MrMikeG

Mart, your right YOU do not need one.
Patrick, your set-up says it all! Why you would think increased AMPs would show up in that little mini servo with tiny wiring is beyond me, Kind of like putting a 4 cylinder in a Hummer and telling the world how good of fuel economy your getting!

patriktegelberg

Allegory? What I did was to check my receiver for a weak BEC, it had none. Servo is to small to benefit much from thicker wiring and I blamed the voltage drop on internal resistance in batterypack. Just slamming a Y harness in the box will to many setups make no discernable difference.