New Forum - 3DGroundschool!

[madmax]

Discuss all topics related to 3D Flying in this forum!

Enjoy!

MD

[Joc]

Hi, just joined the site, i currently live in scotland. i have just bought my first large scale model, its a 30% Extra 300s powered by a ZDZ60 Rv. i have come from a small scale background but want to break into 3D flying. Is anyone able to sent me diagrams of how to set the plane up, number of servos per control surface, how and why you have to mix the channels, the best type of servos to use under the strains that will be put on the model. Any help would be greatly appriciated as i cant wait to start.
Cheers
Scott.

[red_z06]

absulutely no mixes are necessary to fly 3D. I fly with only one rate at 30-35deg on aile, 45-50deg on elev and rudder max allowed. In order to fly at these deflections in all conditions you need to put a curve on th throw called exponential. Idealy upto 40-50% stick throw it acts as a low rate setup and further u push the stick, the deflection increase. For example if you jog memory to school days x = y^2. if x = tx stick movement, then y = surface deflection. This is a crude example but explains.

Is it a must? No! If you have golden finger, and you can handle very very small stick deflection, you can fly without ( for example cheap 4ch tx )

I typically use 70-80% expo on elev, aile and 50-60% on rudder.

First mix most people add is rudder to elev mix and rudder to aile mix. This helps the plane track better in K-E flight. Again, it is not necessary as one can manually add elev and aile to keep the plane flying K-E. But doing it makes flying easier. Every plane flys differently so experiment is needed. Idealy during the K-E flight, one would adjust only rudder and throttle.

One mix I found absolutely necessary though is as futaba calls ailebator ( elev halves act as aile in a mix ). This increases aile effectiveness. If you have a plane like GP patty extra, it does not have inboard aile and during torque roll, you can't stop the rotation as aile alone is not effective enough to counter engine torque.

As for servo torque for 3d planes (aggressive) I use following rule of thumb.

Aile (total ) = 1.5 x weight of plane (wet) in oz.
for example 16lb wet weight of GP patty wagstaff is 256oz.

so Aile Torque = 1.5 x 256oz = 384oz or 192oz per wing (it looks like hitec 5945 spec at 6v and for mild, down to hitec 5625 to 5645)

Elev (total ) = 1.0 x Wet weight in oz. (Hitec 5625 or 5645 at 6v)
Rudder = 1.5 x wet weight in oz. (2 hitec 5945 or 1 hitec 5955)

In most cases as long as you keep the speed low to keep these huge surfaces from flutter, 1/4 of above rule can fly the plane. It just would not do crisp maneuvers ( i.e. rolls would be slower etc ). However in the case of rudder, if you have less than adaquate torque, it will not hold K-E flight where most flights other than K-E happens in neutral surfaces but K-E requires rudder deflected towards upper wing ( top rudder ).