rszanti

I've purchased a Losi Truck with an XR2 radio, R-122 Rx & Z270 servos. It's my first venture into running RC cars, all my previous experience has been with planes. I'm attempting to setup the steering and after having read through the XR2 instructions for what must be the 10th time, I'm still confused.

To start, my initial confusion has to do with the "Travel Adjust" (pg 14) - it claims the travel can be set from 0 to 125%. Since servo travel refers to the angular movement of the servo and all servos are rated at a specific maximum (typically 30, 45 or 60 degrees either side of center), how can the servo be set to move to 125% of its normal travel ?

This question drove me to look for Z270 info and I have not been able to find out what is the rated travel of a Z270 ..... or a Z250 or any other servo by JR. How many degrees of travel is possible with the Z270 ? Where can info such as this be found ?

Assuming there is some information I'm missing that will alleviate my above confusion, I went on to attempt to understand the "Steering Rate" adjustment (pg 15). The instructions state the steering rate is a percentage of the travel adjust value. How can a rate (distance/time) be a percentage of travel (distance) ?

Since the Z270 is rated at 0.19 sec/60 degrees, I'm assuming that setting the steering rate to 80% means the actual servo rate will be 0.15 sec/60 degrees (80% of 0.19) over the full range of servo travel. Is this correct ?

And then there's the "Steering Dual Rate Trim" adjustment (pg 20) - here the instructions claims the "dual rate value" can be "increased or decreased" through a range that is 40 to 100% of the "total dual rate established in the Steering Rate Function". What "total dual rate " ? - there is no "total dual rate" mentioned in the Steering Rate Function on pg 15. So I'm totally lost.

I would like to setup the radio so I got a slower rate of servo motion in those long high speed straight-aways and a higher rate when I'm trying to turn tight corners with maxed steering wheel input. But I'm not sure if it can even be done. Maybe a thorough understanding of what the radio can do will make this possible but the existing instructions won't get me there. Can you please clarify this area or send me somewhere when I can pick up the info I need ?

Thanks
Richard

dsnyder

That is because a servos "normal travel" is not all of the travel available. But the normal travel is set to 100% travel adjust so that you can increase or decrease as necessary. A servos maximum rotation is up to around 120-150 degrees, but with most radio systems it is difficult (sometimes impossible) to move them that far with the radio system.

The steering rate function works much the same as travel adjust. As the manual states that if you set the rate to 80% in the steering rate, you will have 80% of the throw of 100% in travel adjust

No, the speed capable of the servo is unchanged by the steering rate. The servo will move 60 degrees in the same amount of time. The speed you will see however varies on how far you are actually moving the servo.

The total dual rate value is set in the steering rate adjustment. The dual rate trim allows you to adjust the steering rate (overall steering available) while running the car etc to set the reaction as needed for track conditions.

What you are asking for here seems to be exponential which the XR2 does not have. Exponential is used to lessen the reaction around the center position, yet still have full throw for cornering. This changes the reaction curve and on radio systems that have it you can adjust the percentage to get the feel that you want. The XR3/XR3i, XS3, and the R1/R1 Pro have exponential.

rszanti

Thanks Danny

That clarifies a lot.

Guess I need to add an upgrade to my Christmas list as exponential is where I would like to be.

Thanks again
Richard

dsnyder

No problem! Let us know if you have any further questions.

carlo_farrales

Hey guys I got a 2nd hand radio system (XR2) and it did not come with a manual just 2 recievers and the radio. Pls. if anyone knows where i can download the PDF file or any site that may give me any MORE information on hte XR2 radio pls just post it thanks

dsnyder

You can find a manual for the XR2 here. http://horizon.hobbyshopnow.com/shar...127-manual.pdf

carlo_farrales

thanks bro