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Old 05-17-2011, 02:05 PM   #1
deepcube
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Default Question about beginner d/r and expo settings

After flying the blade msr for a while I picked up the mcp x as my first collective pitch heli. I went through and set up my transmitter (dx6i) as recommended in the manual, setting the d/r and expo to 70% +30% for the cyclic. After everything I've read about collective pitch helis I was ecstatic to find that I could keep it in the air, even if the hover wasn't pretty. At some point between flights something went wrong with my dx6i and the settings got lost. After a little confusion at the pitch being reversed, I fixed that and started flying again. A battery or two later I was surprised to find that I had been flying (hovering) with d/r and expo at 100% and no expo. But I was more surprised when I realized that I liked the feel better with these settings. I've been hovering, moving the heli around a bit while keeping it tail in, and doing a few fairly tame forward flights from side to side in front of me.

Now for the question. Is it a bad idea to be flying with these settings (d/r 100% and no expo)? As I start progressing into more challenging flying, will this come back to bite me?
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Old 05-19-2011, 10:32 AM   #2
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You are going to get a lot of opinions about this. But here are a few observations: The pro's all talk about using expo. I challenge one 3D Expert or Master (verified) to step up and say he doesn't employ some expo on some control surface,

Also, I reccomend you qualify the people giving you advice, by asking them what their own flying skills are capable of. And don't accept "I do 3D" as an anwer. That term is way to loose. It has too wide a variety of meanings.

Here are my qualifications: Trex700e, flips, rolls, loops, inverted forward flight, upright backwards flight, hovering all directions upright and inverted, nose down funnels, forward hurricanes. I cannot, tic-toc, funnel nose up, or piro-flip.

That being said, I ABSOLUTELY USE EXPO!

Now, don't forget, RATE isn't really necessay. The swash settings are going to control your roll/pitch rate.

On my Trex 700 I do not use any EXPO for the rudder. Instead I have a pretty stiff tension on the Throttle/Pitch/Rudder stick. My Travel Adjust menu was used to set the rudder rate.

My Alieron/Elevator use EXPO and for my three Governed Headspeeds, they change.

In normal mode 1, headspeed 1600, I use 10% Ail/Elevator
In idle-up 1, headspeed 1900, I use 15% Ail/Elevator
In idle-up 2, headspeed 2100, I use 18% Ail/Elevator

If I don't use the EXPO then my stunts tend to get sloppy, because I am jerking the stick very quickly and that increases the risk of pulling in a different direction.

People who just hover around, may never have noticed the need for EXPO, because they aren't doing those rapid stick movements and can be careful only to move the stick in the desired direction....So, again, qualify your advice givers!
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Old 05-19-2011, 10:58 AM   #3
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You can always change the settings again, and you quickly adjust to different 'feels'. Fly with whatever you think feels ok for now, and occasionally change them a little just to feel the difference. Over time you'll develop your own feel for when there is too much or not enough of something. It's a taste thing.
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Old 05-19-2011, 11:30 AM   #4
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Like Danyl said, this comes down to personal prefs. I also use expo on every heli. How much changes from heli to heli as to how sensitive it is around center stick. As for the MCPx I feel the 70% dual rate is not needed but for me expo is needed when I want to be smooth with it. Sure I could get use to flying it without expo but I just don't feel the need.

If you really want to play around and feel the difference in flight, tie the expo to a switch. This way you can turn it on and off in flight a see for yourself which you really do like better. Again it is a persona pref.

As for some Pro's using it or not, I will argue a bit with Danyl here. I know some top guys that never use it like Jason Bell for example. Others I know do use it. So in fact there are top guys not using it as again it is a personal pref.

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Old 05-19-2011, 12:14 PM   #5
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Thanks for your responses. Seeing as today is the first day this week it isn't raining, I think I'm going to go outside and play around with a few different settings to see how they feel.
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Old 05-20-2011, 08:28 AM   #6
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just for a reference point for big helis like 550/600/700 align trex , how much expo is too much to stop you from advancing your sensitivity in flying skills?

and do you add expo on rudd/ail/ele or just ail/ele?
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Old 05-20-2011, 10:27 AM   #7
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Obviously there's no problems using expo, it's helpful, but too much will have the servo travel become somewhat unpredictable? I don't know if that's the right word, but, they'll move very little for the first portion of stick travel. Then, as you get closer to full stick they'll lunge toward the end of travel. So all in all, there's definitely a happy medium. I wouldn't think there should be any reason for any more than 30%-40% expo, any more than that starts putting it into the "wierd" territory. I'm no expert for sure, but I just can't see higher expo numbers than that being helpful. Perhaps Finless' video on expo may be of benefit? Here's the link:

http://video.helifreak.com/?subpath=...me=expo101.wmv

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Old 05-21-2011, 09:17 AM   #8
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Expo is inherent in a system the converts rotation to linear motion. The reason we have it available is to counter the expo that is already there! The control surface moves faster in the center of your stick since that is where the control rod is the closest to tangent to the circle of motion. The control surface moves slower as you rotate, and would stop and regress if the servo rotated too far.

If you want the surface or swash to move linearly with your finger, you need to flatten the response of the transmitter to about 30% expo! Then you are linear! Provided of course everything is set up square and symmetrically... It is just personal taste, but expo isn't their for beginners, it is there to make the system behave linearly if you wish.
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Old 05-21-2011, 02:03 PM   #9
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Quote:
Originally Posted by tgilton View Post
Expo is inherent in a system the converts rotation to linear motion. The reason we have it available is to counter the expo that is already there! The control surface moves faster in the center of your stick since that is where the control rod is the closest to tangent to the circle of motion. The control surface moves slower as you rotate, and would stop and regress if the servo rotated too far.

If you want the surface or swash to move linearly with your finger, you need to flatten the response of the transmitter to about 30% expo! Then you are linear! Provided of course everything is set up square and symmetrically... It is just personal taste, but expo isn't their for beginners, it is there to make the system behave linearly if you wish.

Beat me to it, and said it better than I was going to
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Old 05-22-2011, 06:35 AM   #10
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Quote:
It is just personal taste, but expo isn't their for beginners, it is there to make the system behave linearly if you wish.
Just making sure I'm understanding this correnct. If I just started hovering no expo would be ideal?
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Old 05-22-2011, 09:06 AM   #11
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BOB that safety video #1 rocks couldnt stop laughing!
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Old 05-22-2011, 10:43 AM   #12
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mCP x has linear servos so the inherent expo that comes from a rotating arm to linear motion isn't an issue. ( really don't understand why RC Hobbies as whole don't use linear servos )

The mCP x was my first CP heli as well. The default 70-30 cyclic settings were way to nimble while learning my orientations in the tight confines of my house. especially coming from an mSR where you had to make pretty aggressive stick movements to do anything.

So I started at 30-10 until I got my upright orientations, once I was comfortable with those I started to gradually work my way to 100-10. Since then the only change I've made is taking the travel on my rudder from 100 to 125 in both directions.

But as others have said, you just got to find what works best for you and the way you want to fly. As your skill increases most likely your opinions will change on what the best settings are.
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Old 05-23-2011, 02:16 PM   #13
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Quote:
Originally Posted by tgilton View Post
Expo is inherent in a system the converts rotation to linear motion. The reason we have it available is to counter the expo that is already there! The control surface moves faster in the center of your stick since that is where the control rod is the closest to tangent to the circle of motion. The control surface moves slower as you rotate, and would stop and regress if the servo rotated too far.

If you want the surface or swash to move linearly with your finger, you need to flatten the response of the transmitter to about 30% expo! Then you are linear! Provided of course everything is set up square and symmetrically... It is just personal taste, but expo isn't their for beginners, it is there to make the system behave linearly if you wish.
I see what you mean, but how is slowing the initial servo travel going to help that? Won't it just make it worse? And how does it remedy the last part of servo travel? Seems to me the motion of the linkages toward the end of servo travel in either direction are going to be the slowest. Expo reduces the initial movement of the servo to prevent unintended inputs (like shaky thumbs ) so that you can hover smoother, at least that was what I was under the impression of. I'm no geometry expert by any means, so I'm asking genuinely to gain a better understanding. I DO know that the geometry on my 500 links to the swash are setup on an angle to minimize that effect, explained here:

http://video.helifreak.com/?subpath=...ame=geo101.wmv

and that explanation was very easy to understand and once I saw it explained as such, it really made alot of sense.
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Old 05-23-2011, 05:24 PM   #14
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Let's get past the idea that using less expo is somehow more "expert" or indicative of progress.... Use it to make the heli respond as you like. Putting 30% in causes the movement of the tail surface to more linearly follow your finger input. Making the stick more or less sensitive around the center where you are hovering is a taste thing.... Your fingers are very analog and have higher resolution than the servos.... As you learn, you respond more appropriately. As a beginner you need to have the machine be slow so you can catch yourself, and that is why people slow done the D/R and put a bunch of expo in. I think, you do what it takes to get to the point where you don't crash a lot, then start fiddling until you like things. Part of the hobby...
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Old 05-23-2011, 06:58 PM   #15
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Quote:
Originally Posted by tgilton View Post
Let's get past the idea that using less expo is somehow more "expert" or indicative of progress.... Use it to make the heli respond as you like. Putting 30% in causes the movement of the tail surface to more linearly follow your finger input. Making the stick more or less sensitive around the center where you are hovering is a taste thing.... Your fingers are very analog and have higher resolution than the servos.... As you learn, you respond more appropriately. As a beginner you need to have the machine be slow so you can catch yourself, and that is why people slow done the D/R and put a bunch of expo in. I think, you do what it takes to get to the point where you don't crash a lot, then start fiddling until you like things. Part of the hobby...
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Old 05-24-2011, 03:30 PM   #16
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Absolutely, totally agreed. I wouldn't have suggested that expo was just for noobs, but is a help for noobs none the less. If it feels right, fly it that way I say I just was trying to get my head wrapped completely around the concept. I had most of it, but now I think it's all there. Thx for input.
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Old 05-26-2011, 04:40 PM   #17
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I guess I can answer this since I'm qualified

Fly what you feel translates your intended movements to what the heli does the best.
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Old 05-28-2011, 03:00 PM   #18
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I think expo can be very helpful. When tring to fly very precise a little bit of expo helps keep you from overcontrolling. Flying a fast hurricane close to the ground expo helps me to keep movements smooth. When hovering it tames the control around mid stick and can help any level of pilot. I run 15% usually and it just tames it a touch without being very noticable. Just my .02
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Old 05-29-2011, 02:25 AM   #19
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If you want to tame a wildly moving heli, then reducing the distance the servo moves with d/r is also an option.
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Old 06-02-2011, 10:50 AM   #20
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I fly a 600 sized Trex clone and I use 20% expo on my aileron and elevator, but none on my rudder. Initially, I had aileron and elevator on 40%, but it was WAY too mushy. This seems to do well for me in just hovering and normal type flight. I don't get into 3D. I prefer scale flying and also use the bird for Aerial Photography.
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