What the heck's expo?
 

I think I understand the functionality of dual rates (but have never used this) but could someone PLEASE explain what EXPO (exponential) is and why I would want to use it?

RE: What the heck's expo?
 

Hello expo makes the sticks less sensitive around natural. That is to say when you say move the alrons just a little it well take more stick movement to get them to full .

RE: What the heck's expo?
 

check this tread,it should help you [link=http://www.rcuniverse.com/forum/m_1668510/anchors_1669597/mpage_1/key_/anchor/tm.htm#1669597] EXPO[/link] also if you click on my name at the top of this tread go in to my profile and i had alot of the same questions that may help you when i first started good luck

RE: What the heck's expo?
 

Thanks for the link. And since I'm asking, what the heck are flaperons? How would I set them up and why would I want to?

RE: What the heck's expo?
 

flaperons are supossed to help with slowing a real plane down for landing like air brakes also its supossed to help with lift when taking off . in order to set up flaps you would use ch1 and 6 .and depending apon your radio you would set this on flps mix. personally i dont use them i guess it looks great for those more realistic planes.infact any time you use seperate airelons the funtion is always there my radios use a knob you turn.

RE: What the heck's expo?
 

Here in Japan, they call radios "propos" -- short for proportional. Funny that will "modern" computer radios using expo we can undo the very thing "propos" are named for!

I had a heck of a time flying my Seagull Spacewalker II today on it's maiden flight and I was wondering if my 0% expo settings had anything to do with it. Probably just my dumb thumbs and more wind than I can handle at the moment -- and maybe a CG issue.

RE: What the heck's expo?
 

Flaperons = Flap & ailerons. It's basically setting up uyour ailerons to serve double duty as flaps.

You need two separate aileron servos and a transmitter with the ability to mix them properly. Futaba uses a "flaperon" function, or you can use most computer radio's free mixes to set them up.

In flight, when the flap knob (or switch) is enganged, both ailerons drop to act as flaps, but using the aileron stick still moves them to act as ailerons, albeit to a lesser degree on the "down" side.

Hope that helps.
Dennis-

RE: What the heck's expo?
 

Dennis, thanks for the helpful explanation. Now I need to go home and play with my radio!

RE: What the heck's expo?
 

It's complicated, but once you understand it, you'll see why it's so helpful.

It's sort of like Dual rates without the disadvantage of giving up full control.

With dual rates, control inputs are lessened, so the plane flies more gently, but now, you may have trouble pulling out of a loop because you have less than full control input.

With Expo, The Tx converts the stick's input to an exponential curve (An exponential curve is a Mathematical Logarithm... If I totally understood what that means, I never would have flunked Algebra, So just accept that and let's move on)

As you move the stick, the Tx put's out Less signal than you are inputting (Like Dual Rates) the difference is, the more you move the stick, the more output signal is generated until - at full stick deflection, you have full control surface deflection.

In the pic below, you can see (Blue Circle) that the stick (red line) moves a lot for only a small amount of control surface movement (black line)

Whereas at the end of the stick travel (Green Circle), The stick moves a shorter distance to get the same amount of Control Surface travel.

So when you give gentle control inputs, you get very gentle input (Like with Dual Rates), but as you increase the amount of input, you get full control.

RE: What the heck's expo?
 

abufletcher,
I don't think you mentioned what brand of radio you are using and nobody posted that you may need negative expo or positive expo. Futaba radios need negative (-) expo programmed to make the sticks less sensitive around center. JR radios need positive (+) expo. If you program the wrong one you will make the sticks more sensitive around center.

RE: What the heck's expo?
 

Good point Jammer

RE: What the heck's expo?
 

Well, hard to say. Expo won't help if you have a tendency to over-control and throw the sticks around, in fact, it can make it worse in such cases. Make sure the amount of control surface throws are set up correctly and fly it with nice gentle inputs on the sticks. You may want to try about 20% expo on low rates but I wouldn't go any higher than that on your Spacewalker. The Spacewalker is not typically a good "windy day" plane. Re-check your CG to make sure that's not a problem.

RE: What the heck's expo?
 

Mike and Jammer, thank you both for your assistance. I do basically get the concept of expo now and it generally seems like it should be a good thing for novice pilots (and certain types of advanced flying by advanced pilots). I think I'll try setting it up with 20%.

After playing around with the parameters in RealFlight, it seems clear that the CG was way off. I tried pushing all the expo and throw setting parameters around but they had very little effect on what was basically a smooth flight each time. But when I moved the CG back -- bingo an almost perfect simulation of this morning's wild ride. How this is possible since the plane balanced really nicely right at the given CG point 7.7-8cm back from the leading edge I just don't know but the plane clearly needs more weight up front. I just have no way of estimating how much. BTW, I do have a 52FS but to install it I'd have to remove the current engine mount and installing another with room for the carb and this would probably also involved cutting open the tank area and doing some recovering.

The Spacewalker II may not have been the best choice for the typical conditions at my new field but I suppose it will given me just what I was looking for -- a plane that will push me to really learn how to fly (and land) in a range of conditions!

RE: What the heck's expo?
 

Jammer, BTW, I feel I've got a good handle on the "delicate thumbs" idea and normally my movements are very minimal -- just barely perceptible to an onlooker probably. But not this morning. This morning I was yanking the stick all over the place to try to get out of all sorts of scary places. Although I crashed landed at the end, I should take some solice from the 50 other moments in the 3 minute flight that I managed somehow to stave off a crash!:D

Oh, and I'm using an Airtronics VG6000.

RE: What the heck's expo?
 

Don, where is your battery pack located?

RE: What the heck's expo?
 

Mike, the CGing was done with everything in place and this means the Rx and battery in the area forward of the bulkhead the wing plugs into, i.e. right behind the fuel tank. Certainly there is space to move the battery even further forward and I'll do that once I've gotten the larger wheels (since they're also forward of the CG).

I'm thinking of placing the CG point at about an inch forward of the sheeting edge and hoping that that will do the trick. I'm concerned though that others have been able to use the recommended balance point.

RE: What the heck's expo?
 

This just sounds strange. I ahd the battery pack on mine behind the servos, and still had to add lead to the tail (with an Evolution 45)

RE: What the heck's expo?
 

I'm not using the cowl but I can't believe that would be the deciding factor -- particularly since I added some lead (about 6 squares of that stick on stuff) to the firewall.
I've been doing some more post-crash analysis with RealFlight. I set up to copies of the Spacewalker and gave both copies a smaller engine (61FS vs the default 91FS). Then on one copy I dialed in positive (nose-heavy) 2.0 under fuselage CG and on the other dialed in negative (tail-heavy) 2.0. BTW, the sim model's default is +0.8 I'm not sure what that means.

Anyway, the severely nose-heavy version is still very flyable even for a novice flyer like me. On the other hand, the severely tail-heavy version is absolutely impossible to fly -- it always crashes within seconds of take off no matter what I do. The sim becomes flyable (but still challenging) with a CG setting of about -0.5. As a separate experiment I moved the throws in the sim all over the place and was still able to handle the plane. I've also flown with the wind (5-10mph) in the sim turned both on and off with no major effects on flyability. All this supports the probability that my Spacewalker, for whatever reasons, is definitely tail-heavy despite being balanced at the recommended location (7.5-8cm back from the leading edge which corresponds with the main spar and is at about the 30% MAC location). Just can't figure this out.

Being an ARF there is little I could have done to screw up the construction (and the construction itself looks great and true). Tail feathers are all on straight and square. I even went so far as to put the "heavier" male pilot figure in the forward cockpit (since it's closer to the CG) despite wanting to express a little solidarity with the women's liberation movement. :D

I guess the only solution is to add some (more) weight to the firewall and try again -- it better weather!

RE: What the heck's expo?
 

BTW, on my upcoming trip back to the US I'll pick up my GP incidence meter just ot check whether there could be some engine misalignment. But I don't think this would have resulted in the tiger ride I went on.

RE: What the heck's expo?
 

Could it be that Japanese air just isn't the same as American air? :D (A Japanese ski resort did once turn down an equipment bid by a German company saying that "German snow is different than Japanese snow.")

RE: What the heck's expo?
 

The description of how you said it flies definitely sounds like it's tail heavy. It just seems strange that I had to add tail weight, while you had to add nose weight.

RE: What the heck's expo?
 

Maybe there was just a whole heck of a lot more wind that day that I imagined. The field is on a sort of protected plateau and wind could have been screaming across (from my back) overhead and I'd never feel it on the ground (and the windsock might not even show it). I know it really wanted to balloon on the right side of the field where the glider guys fly and I had to work to bring it back in on the inbound leg.

It didn't have any problems with wind on take-off.

Still, this WAS the day before a typhoon hit with full force -- and it rattling the windows as I write this. Probably the safest thing to do is set it up nose-heavy (which should still be flyable) and then slowly work back to a perfectly balanced plane. I don't want to take a chance flying it tail-heavy EVEN A BIT again! It may just be an ARF but I've already BONDED!!! :D

RE: What the heck's expo?
 

One more thing. I checked and the Evolution 46 has a weight of 13.10 oz. (I'm assuming without muffler) and my Magnum 40 is listed as 13.5 without muffler and 16.4 oz with muffler. My engine is mounted as far forward as the brackets allow. BTW, it did notice one of the other posters here commented that his flew kind of strange at slow speed.

RE: What the heck's expo?
 

abufletcher,
I don't own this plane but I do have a GP 1/4 scale Spacewalker. From your description of how the plane was put together it doesn't seem logical that it's tail heavy. I would say re-check the CG on a balancer to see if it is within specs. Should be about 30% of the wing chord for that plane. I wouldn't base your decision regarding the CG on your findings in RealFlight. It could have been something else that gave you a wild ride. My SW needs very little elevator travel, about 5/8" up and down. Maybe you have too much throw on yours. Just a thought.

RE: What the heck's expo?
 

I have this plane with an evo 46 NT. As Minnflyer, I have the battery behind the servos.

Keep in mind that the space walker II on Real Flight is not for the Seagull Spacer Walker II. It is for the great planes one. I don't know how accurate RF is on flight characteristics, but I can tell you the one on RF does not fly like my Seagull one. There is a very noticeable difference.