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Old Mar 08, 2009, 10:19 PM
"OLD CHEAPSKATE" FOR SURE
nakman8's Avatar
Joined Dec 2004
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exponential settings

Can you use too much exponentilal on your radio trim controls?
Seems to me that over correcting is big problem for beginners will a healthy % of exp.help?
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Old Mar 08, 2009, 10:34 PM
Deletedfor proving Nauga wrong
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You can have expo set soe "high" that you have to move the stick 75% of the disctance rom center to full range to get any noticeable effect...

That would make the aircraft rather hard to conrol because you got.. nothing, nothing, nothing... TOO @#@$ much.

The best way to cure beginners of overcontrolling is... make them practice with no expo.
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Old Mar 08, 2009, 10:37 PM
Debris Fields 'R' Us
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Union City, Ca
Joined Mar 2005
98 Posts
It's been my experience that with too much expo can lead to problems. You will have tame movement around center but as soon as you need a little more control and move the stick to far you suddenly get near full deflection on the control surface. I prefer expo around 25% on ailerons and elevator, 0% on rudder. I use this with dual rates that are set for less throw than normal. The alternate switch position on the dual rates I set for much high throw. So I can have fun but when I get the shakey thumbs I back down to the low rates for a while. These lower rates also cured my tendancy to tip stall when landing.
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Old Mar 09, 2009, 05:43 AM
I am ready for HHAEFI!!
powerlines's Avatar
United States, GA, Cochran
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20-30 at the start.. That will make you softer in the middle..

Remember + for JR and - for futaba..
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Old Mar 09, 2009, 07:05 AM
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Jacksonville Fla.
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I am going to disagree with the majority it seems....as this is a beginners forum....I would not recommend any expo to help a beginner learn....what a student learns now he may have to un-learn later...for the majority of people learning to fly expo will be a crutch...the 2 biggest things you learn as a student are 1. seeing the airplanes attitude at different angles and 2. (this is where expo hurts) muscle memory..this much stick movement gives the airplane this much movement...
Now if you had a student that had a condition where his hands shook..or perhaps didn't see very well then expo could help these folks.....
learn to fly with their thumbs by practice practice practice
However expo does have it's place on aerobatic airplanes.
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Old Mar 09, 2009, 07:48 AM
Will fly for food
Maryland
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With standard setups you have reverse expo built in, so a bit of expo actually makes the controls more linear.

But run what YOU like.
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Old Mar 09, 2009, 02:11 PM
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I have never used expo but would'nt hesitate if the model was to touchy near the center.

With some radios if you set it to max expo then the stick will essentially act like a switch...Nothing until you hit the stop then full throw.
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Old Mar 09, 2009, 02:51 PM
Deletedfor proving Nauga wrong
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Quote:
Originally Posted by Pinecone
With standard setups you have reverse expo built in, so a bit of expo actually makes the controls more linear.

But run what YOU like.
Both the servo arm and the control horn are moing in an arc. If the length to pushrod connection is the same, you get identical rotation angles at both ends.

Thus.... the "apparent reverse expo" is not due to the rotational servo arm movement.

A control surface gives more effect per degree of deflection near neutral than at large deflection. (the first degree of aileron, going from 0 to 1, adds more roll rate than the 20th degree, going from 19 to 20)

10% to 30% expo, depending on the plane, can compensate and make the effect linear per deg of stick movement.

The effect is also dependant on airpeed... so the amount of expo to compensate would change with throttle setting.
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Old Mar 09, 2009, 05:44 PM
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Wellington, NZ
Joined Aug 2006
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Thanks for that explanation, fh.

Yep, too much expo = too much stick movement = slow response. I added too much to my new cap232 and quickly put it back to around 20%.

The other approach for beginners is to restrict the throws mechanically.
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Old Mar 10, 2009, 12:23 AM
trying to miss the ground
blademaker22's Avatar
United States, ID, Rigby
Joined Oct 2008
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Quote:
Originally Posted by fhhuber506771
10% to 30% expo, depending on the plane, can compensate and make the effect linear per deg of stick movement.
Yep. For my planes anyway, 20-30 percent seems to give a nice linear feel in the air. Any more than that and it starts to feel like Im not as connected to the airframe.

I do set up 50% expo on ultra high rates sometimes. I never just fly around with the switch on though. I switch it on to fly a really wild maneuver, and then switch it back off. This is unnecessary for most "normal" (not 3d) aerobatics.
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Old Mar 10, 2009, 05:03 AM
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Jacksonville Fla.
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Gentlemen: Let's not loose the orginal question here....
1. Can you have too much expo
2. can expo help a beginner learn not to over control his airplane
the answer to the first part of your question is yes you can have too much expo...the airplane wouldn't respond to inputs and then all of a sudden it would...
to me it would make over controllering the airplane worse if expo was removed...
part of learning to fly is controlling the aircraft not over controlling the airplane..As an instructor I know we want to see our students do well..but there is no subistute for practice....part of the learning curve..your student will be a better pilot if he learns to fly with his thumbs...
Since I have so far condemned expo Let me have the chance to tell you when I use expo....I have a 50cc gas Pitts Python..the control surfaces are good sized so a little stick movement goes along way...I use expo on low rates..to dampen the controls around center....
good flyin to ya all
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Old Mar 27, 2009, 11:24 AM
3D Soon-To-Be....
Marcinb's Avatar
Chicago
Joined Apr 2008
797 Posts
Beginners should not use any fancy options at all.
Just basic four channel or three channel control. Once they master that, you can add flaps, spoilers, and expo. But you don't start off with such things.
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Old Mar 27, 2009, 01:56 PM
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Quote:
Originally Posted by Marcinb
Beginners should not use any fancy options at all.
Just basic four channel or three channel control. Once they master that, you can add flaps, spoilers, and expo. But you don't start off with such things.
Why not? IMO anything that will make it easier for a person to learn to fly is a step in the right direction. Expo smooths out the middle and can help a new pilot stop over controlling. As skills grow, take out the expo.

When I taught my children to drive I did so on a car with an automatic transmission, power steering and power brakes. They also learned how to drive with a manual transmission, but basic control of the car, judging distances, etc came first. Expo seems like the same thing to me.

I agree that a new pilot shouldn't be flying a plane with flaps required for landing, or trying to use flaperons. Most basic trainers don't include either, though.
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Old Mar 27, 2009, 03:16 PM
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As one who has instructed quite a few new flyers, I have found that most times a bit of exponential a big help in learning. The tendency of most new students is to over control and this helps them to prevent it. How much? Depends on plane and individual, start out at about 30% and adjust as necessary.
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Old Mar 27, 2009, 03:33 PM
3D Soon-To-Be....
Marcinb's Avatar
Chicago
Joined Apr 2008
797 Posts
I believe you should learn to fly without anything. As has been said before, it can become a crutch. My opinion is, that anybody who doesn't NEED it, shouldn't use it. When I say need, someone who has shaky hands etc.
Start out with the basics. How to fly, orientation, and things like that. Learn to fly without any aid from computers or control. Then as you progress, you can add things on to make your flights smoother and better.
I feel expo shouldn't be used for a beginner.
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