Throttle Exponential
 

How important is it to have throttle expo on a gas engine for hovering? I'm using a DX7 Spektrum radio which doesn't have throttle expo in the airplane mode, and I find the throttle just too touchy to hold the plane. The helicopter mode has expo capability, but there are only 3 programmable mixes in that mode.

RE: Throttle Exponential
 

what kind of exhaust r u running ?

RE: Throttle Exponential
 

I'm running a Jtec Pitts on a DL50? Why do you ask?

RE: Throttle Exponential
 

Chuck,
The DX7 doesn't have throttle expo "although it should", but you can sort of fake some expo in anyway. I had the same problem so I started playing with the offset and servo throws. I found that if you offset the center big time and then adjust the throws to give you the full range of motion you can make the bottom half "or the top" less sensitive. On mine the first half of the stick only moves the throttle a quarter of the throw and the top half moves the other three quarter or there abouts. You'll have to adjust the throttle servo arm but that's easy...
There's my two cents... hope it helps.

RE: Throttle Exponential
 

....in airplane mode....

RE: Throttle Exponential
 

you can try using both your throttle servo arm and carby arm for a different gear ratio. you may have your model set up with higher gear rates such as; outer on the servo and inner on the throttle or vice versa.

RE: Throttle Exponential
 

chuck,

I wanted to make sure you could not play with header length. Also are you running a throttle mix to make the rpm linear?

RE: Throttle Exponential
 

As mentioned in the original post, the issue is the DX7 radio doesn't have a throttle mix in the airplane mode. I guess I called it throttle expo, which confused the issue. So if throttle mix will help with hovering, I'll have to try the heli mode.

RE: Throttle Exponential
 

i found using the travel adjust can help a bit also as you can change travel for the low and high end of stick movement.
cant recall quite what i did but i think the low travel adjust was dropped to about 40%, so up to half way on the throttle stick the servo would only have 40% of its original movement

RE: Throttle Exponential
 

I was wondering about that (in an airplane). With my 9C I can make the stick increments tie out to a series of even RMP progressions but the "stock" settings definately favor a natural exponential because the last 30% of the stick movement is a lot more of the engine's range than the first 70% on most of my models (IMHE). Maybe that's just the way I usually set-up my linkages??

On one of my models I took the time to tach out even linear RPM steps for the stick movement through idle, 25%, 50%, 75% and full. It was WAY more work than benefit as I usually fly more by "feel" than set positions.

RE: Throttle Exponential
 

Thanks for all the input. So is it safe to assume from this discussion that having the ability to program a throttle curve is beneficial to helping with hovering a plane?

RE: Throttle Exponential
 

It definitely makes it easier to hover for me. I flew 3d planes for years without a throttle mix and hovered just fine, but with my new radio, a 9303, I flattened the curve around half throttle and hovering at a constant altitude got a lot easier. Just less moving the throttle stick to keep the engine in it's hovering rpm range.


Mike

RE: Throttle Exponential
 

No mix for me,just offset the servo arm ( not 90 degrees) and it will be less sensitive off the idle