I've got my server arm so that it is not square with the server case. It is swept back slightly. This matches up with the snake (ie. straight in out rather than tugging it away from the balsa block that it is glued to) and as the stick is moved, there always seems to be proportional movement at the engine end. However, if I make it square with the servo case then I get what the guy warned against, not a full range of movement at the engine end (ie. the last bit is side to side at the servo end so there is no change at the engine end). Does it matter where the arm is if the movement at the engine end always reflects the stick movement ?

Thanks

Does it matter where the arm is if the movement at the engine end always reflects the stick movement ?

No.

Dr.1

Ditto.

I like to have the full throttle end of the carb to move more rapid relative to the transmitter stick than the low speed direction of the throttle arm.

Enjoy,

Jim

Throttle servo arms should only be 90 degrees to the servo case at around mid throttle. The throttle really doesn't spend much time at neutral, like elevator, rudder and ailerons, so it should rest where ever the throttle stick places it. I try to get mine set-up so I get a good reliable idle with the throttle between high idle and the middle on the trim. Then, I adjust so the barrel closes when I press the 'Throttle Cut" button. All I worry about at full open is that I don't stall the servo by hitting the throttle barrel rotation stops. I like to get the barrel as open as I can, however, I've found that RPMs are about as full as you can get, even though the barrel may still be slightly closed.

You new guys should have tried adjusting throttles with the old radios. The only way you could adjust throw was to move the clevis in or out on the servo arm, or throttle arm on the carburetor. With "End Point Adjust" and "Total Throw Adjust", all of this is so easy now!

It really doesn't matter, as long as you get full travel without "stalling" the servo at either end of its travel.

Britbrat's statement is rule number one.

Enjoy,

Jim

Snake?

I'm guessing snake = cable.

I know, just thought it was very "colorful".

Mode one states rule #2 Enjoy,

Jim

With programmable radios, I even try to keep my resolution nice and linear.

You can simply adjust the end points of the radio to avoid binding at either end of the throttle stick, but that doesn't always make it linear.

Have you ever noticed that your engine will seam to be at full throttle or almost full throttle even though the stick is still just slightly over 1/2 way? Thats from programming the end points on the radio, but not paying attention to your overall mechanical setup. You might have 125% travel to reach full throttle, but when the stick is pulled back, you'll only have 40% travel. This is a non-linear setup. At low throttle settings, your stick and barrel won't move much, but once you get the stick over 1/2 throttle--the barrel moves disproportionately quicker.

I want my throttle barrel to be 1/2 way open when my stick is 1/2 way up. I also want my throttle barrel to be 1/4 open when I'm at 1/4 stick. Maintain the linear resolution.

The way to keep it all linear is to adjust all the linkage and servo horn positions mechanically before you start adjusting the radio end points.

You can pull the servo horn off the servo and move it one or two splines forward or backward. Then adjust the endpoints.

I might not have my + endpoint at 100%. It may only be 85% on the + side, but my - endpoint will also be set at 85% to match it.

You may have to adjust the length of the pushrod, and you might have to pull the horn off and move it around several times. But, if you work at it, you can get your endpoints to match each other in the radio. That will give you the best resolution with the throttle.

This is really hard to explain with a keyboard. Hope this makes sense.

Rcpilot, making the travel linear still doesn't do much, most engines have a very non-linear throttle control. The carb could be 1/2 open but be at 11000 of the full rpm of 13500 for example. Thats why some people use a 5 point mix or the like to make the response linear so half throttle is half rpm.

It's not so much making the actual barrel linear as making it linear in your radio.

I knew I wasn't explaining it right.

I want my + endpoint to be the same as my - endpoint. That way I have the same resolution from the TX above 1/2 throttle as below 1/2 throttle.

A friend is always yelling to me that he is flying his new plane at half throttle. He means the throttle stick is straight up. But I can tell that the engine is making probably 90% of its full power. He's not very mechanical.

Enjoy,

Jim

I didn't bring this linear out-put, geometry of the output arm's movement and technical stuff up in my post as it is complicated, difficult to descibe and after all, we're trying to help someone get started.

Guys

It's just clicked ! I now realise where I was going wrong. I was not mid-position with the stick when I was setting up the arm. Now it looks good - nice and linear. I'd somehow got it into my head that I needed to be stick fully back for the mid point !

Thanks all