Hey guys,
I just went out to the field this weekend to maiden my p-51 trainer from hanger 9!! Lot's of fun... but nerveracking at the same time. I had an instructer who was a lode of help and everyone at the field seemed like really great guys. We almost lost it about 20 secs into the first flight because of disorientation when it got far out, but the instructor saved it about ten feet from the tree tops... my heart was in my stomach[X(] Other then that adventure everything went well, and the airbrakes on the wheels didn't negatively affect the flight characteristics. Nothin to fix after the first two flights
Anyways while it was up the instructor trimmed it out with the manuel trim adjustments on the radio, he told me to use the computer on the radio to trim it so that I could put the manual trims back to neutral... How exactly is this done? Thanks for any help you might have. Oh BTW I have a JR 421 computer tx. Thanks
Dave

You sure he didn't mean adjust the clevis's on the push rods so that the trim on the radio could be set back to neutral? Otherwise I guess he was talking about using the sub-trim function which I have no idea about for your particular radio.

Cheers
Vaughan

That's why they print instructions, kid...

Dave,

What he suggested is to use the servo trim feature in the radio to adjust the control surfaces to get the trim tabs set back to neutral. I've used your radio but I cannot tell you where in the settings it is so I'd suggest breaking out the book. It's called sub-trim

There really is no benefit from doing this. It's really no different than just leaving the trims where they are. All you are doing is moving the settings from one part of the radio to another.

Also the radio you have should be the JR XF421EX and if so it's a computer radio so it will maintain all the trims for you.

So what it boils down to is I'd leave it as it is.

Back when computer radios did not exist, it was common practice to mechanically center the trims after the maiden flights to keep the trim tabs on the radio centered. That way it was easy to know where the trims needed to be if you used the same radio for multiple planes. Now a days with computers radios such as yours, it's just not needed

I would recommend adjusting the trims mechanically (on the plane) so you can get the trims set to neutral on the radio. It's just easier.

As for the radio, I have the same one. Turn it on. Push both of the programming switches up and you'll enter programming mode for the current model (it has two-model memory as I recall). Push the left programming button up to select what you're working with (sub-trim, rev-norm, end-point adjusment, etc.) and push it down to select the control to modify (ELE, AIL, GER, RUD, etc.). Use the right programming switch to shift the values for these items up or down.

EDIT: To enter the main programming mode (to set model name, reset model, etc.) have the TX off, hold both programming buttons up and turn it on. Then it enters the main programming mode. You can name your two models, set flaperons or v-tail or whatever, reset the model (clear all entries), and one or two other things I can't remember right now.

well I actually did read the instructions but they only tell you how to get to the sub trim in the controller not how to transfer the manual trim to the sub-trim... I was juts wondering if there was a process to actually transfer the trim without just guessing how many points to sub trim it... thanks