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Expo for precision flying?

Old 04-04-2006, 11:48 AM
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bdunsire
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Default Expo for precision flying?

I sort of asked this question in another thread, and have seen exactly zero replies so..

My situation - another new plane [8D], setup as recommended and I find there is (aileron) much greater control throw than I would typically use, but this are offset by much greater exponential (smoothing) than I would typically use. I'm wondering what you folks (competing at higher levels - Advanced / Unlimited) use.

In this case - my IMAC gas planes (a 33% Edge, CAP 231, and Laser) - aileron I have max deflection (non 3D) to a roll of about 1 per second, and I use expo (JR) at 30-35%. The new plane (QQ YAK 102") - started at their recommendation for throw and expo, (since changed a lot) - which gave a roll rate of about 2 per second (non 3D!), and an expo of 70% or so.

For aileron - do you use large amounts of expo to offset large control throws, or do you use medium expo and medium control throws?

What about Rudder and Elevator - large amounts of control throw vs expo?

In my case, only for 3D elevator, have I ever had expo over 70% before. Actually, perhaps funny, but I never even used expo until I started to compete in IMAC about 10 years ago - and then expo was just rudder. As I 'progressed' I started using expo on the other primary controls (this was in the days before 3D)

Cheers,
Bob
Old 04-04-2006, 12:05 PM
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rcblimppro
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Default RE: Expo for precision flying?

Bob, I use a fair amount of expo on all flight controls. For sequence flying my ailerons have about 30 degrees with expo at 50, rudder is 20 degrees throw and 60 expo. Usually I set the rudder throw so that the airplane will knife edge level at 1/2 trottle and full rudder deflection. Then bring up the expo so that corrections are all but invisable. My elevator has about 16 degrees up and 20 degrees down with 45 expo. You will notice that the throws on elevator and rudder are quite small while aileron is higher. Some sequences have you doing rolling manuvers at slow speeds on a downline thus the added throw. Hope this answers your question. You guys up north are always welcome to come down fly with us at our contests. Our next one is in 2 weeks in Hollister ( 60 miles south of SF ) The last 2 years we have been treated to a show by Sean D Tucker.


Shawn
Old 04-04-2006, 07:35 PM
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bdunsire
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Default RE: Expo for precision flying?

Thanks Shawn, this is quite interesting.

I have about 8 flights now on the YAK, with the large expo and large throw on ailerons - I can see / feel that this will work for me for aileron.

I played a bit with the idea of adding even more expo to this rudder today - along the lines of your suggestion of using expo to mask (as such) corrections even more. I did try the half power knife edge to see how the rudder held up to that test, and I find half rudder throw holds KE - amazingly small rudder amount in the case of this YAK - I think the two 8611 servos helped too .. I don't really have a simple way to decide how much rudder, and this plane has SO much rudder authority, that a small throw seems to work well - interesting..

I guess it is just a personal feel thing, but I added more than suggested for Elevator throw, and I took off a bit of the expo - still more expo than I'm used to but I found the feel around center to be too mushy on Elev for my taste - still experimenting however.

Tomorrow I'll take the Edge out to practise, and after 4 days of flying the YAK with the tons of expo, it'll be very interesting to see how the Edge feels - I'm not ready, with so few flights, to use the Yak for the IMAC even this Sunday - but I can already tell the Yak will be a better IMAC plane - as expected, but what a treat!

Oh - California and IMAC - moved here 8 years ago from Pleasanton - used to belong to both Livermore clubs, and used to do the IMAC contest in NorCal - tons of fond memories, and I see in results a few of my old flying friends are still competing - I do hope to get down to a contest or two..

Cheers,
Bob
Old 04-04-2006, 08:04 PM
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GalenB
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Default RE: Expo for precision flying?

On my EF Yak I am using 10 degrees of elevator throw for IMAC. I've been flying with Kevin Miller (you should meet him on Sunday) and we've been steadily dialing down the throw on all of my control surfaces. My ailerons are still too "hot", but I will fix that next time I go out. I was amazed at how little control throw was needed to fly the Sportsman sequence. Kevin flew the Unlimited sequence on my IMAC condition with no trouble at all. I am finding that less throw with moderate expo 20-40% is working well for me.

I will be out of town on Sunday and will miss the Polar Bear contest. Good luck and I'm sure I will see you at another contest.
Old 04-08-2006, 12:40 PM
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Default RE: Expo for precision flying?

GalenB
i do the same as you very little throw really does a lot if you are not tring 3d. i have 3 flight modes so one mode is for 3d.
Old 04-16-2006, 03:54 PM
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GalenB
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Default RE: Expo for precision flying?

I use three flight conditions -- IMAC, Landing, and 3D. The landing condition is the same as IMAC except all of the mixes are turned off...
Old 04-18-2006, 11:07 AM
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bdunsire
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Default RE: Expo for precision flying?

Related to the question of expo amounts - a bit over a week ago, at an IMAC competition out here, I had a chance to talk with a 'brand name' pilot (not wanting to drop names) - and in a discussion about expo, he made a comment I had not heard before, but I think it makes a lot of sense. He suggested that any expo over 30-35% will result in our losing the direct connection / feel to the aircraft.

I realize that, for non 3-D flight, in all of my planes before the QQ Yak, I use expo in the 25-35% range (JR radios). The higher expo numbers I've been facing with the new Yak are most likely the strange / unusual feel I've been dealing with, and with nearly every flight of the Yak I have been making changes to the expo and rates, just to get it to where I feel most comfortable - but interestingly, the expo is now in the 35% and less range for all (non 3D) surfaces.

Do you folks have limits / targets like that?

Cheers,
Bob
Old 04-18-2006, 11:11 AM
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Default RE: Expo for precision flying?

Bob, I usually use around 20% expo on the elevators and ailerons, and maybe a little more on the rudder for IMAC rates. I do spend a lot more time tweaking those rates versus 3D rates, where it's go for everything and use expo to make it flyable for normal maneuvers.

I gotta know what brand name pilot you were talking to, didn't realize we had such an honor in the NW Well at least since a stud like me left . Unless you were talking to Dave V; I think he was there.
Old 04-19-2006, 07:25 AM
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Tony Fandino
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Default RE: Expo for precision flying?

Guy's i think there is no real correct answer to your question. Every pilot is different and has his own tastes and likes. There are purist out there that do what you describe. But for me what works is lots of expo. I fly around -55 on my elevators with about 12 degrees travel. ailerons are around -65 and rudder at -70 this is what feels good to me. I fly one flight mode for everything and it works for me. I have been told that this may not be tha best approach especialy for andvanced and unlimited but I'm not there yet. I will say that i have had good success doing things like i have described. So Fly what feels best to you, not what everyone else says, only use the advise as a guide and not the rule

Tony fandino
Old 04-19-2006, 10:44 AM
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rcblimppro
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Default RE: Expo for precision flying?

Tony, your setup is very simular to mine and I don't change rates either. I agree that setups will vary from pilot to pilot but between you and I we must be doing something right. I myself am sitting in 3rd in my region and fly Advanced. This is my most successful season I have had in 6 years. The difference for me was over the winter I started practicing more and asked a couple of unlimited pilots for help tuning the airplane and to coach for me.


Shawn
Old 04-20-2006, 08:11 AM
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Tony Fandino
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Default RE: Expo for precision flying?

Yes hard work will pay off. No matter what your setup is Know your airplane, Learn all its good and bad habbits and you will be successfull.

Good luck all

Tony
Old 05-09-2006, 09:08 PM
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Default RE: Expo for precision flying?

I don't like too much expo for precision flight either. I tend to use 15-25 on all flight controls, and only use IMAC and 3D flight modes.

I setup the ailerons for the correct roll rate at the slowest point in the sequence and use expo to get the correct feel in slow rolls. I find that too much expo makes it much more difficult to really nail faster rolls, you either hit it exactly or are off by 10-15 degrees. With less expo you hve more chance of varying the end of the roll to nail it, yet still 'appear' to maintain the same roll rate.

For elevator I setup the throws for nice spins and snaps (some planes need another flight mode for snaps) and then set the expo to get the right feel. Too much expo and you find that you can't make those really small corrections needed to keep the line straight on a moderately windy day, like when it's a little bumpy.

For rudder, i tend to just use the max available, and ~ 20-25 expo. But then I fly mode 1 as well so YMMV. just be smooth on the stick and you've got the etra rudder if you need it... KE loop in unknowns anyone??

I always find that while mixing may fix some characteristic of the plane, it will (almost) always hurt you somewhere else. Take a downline mix that is 2-3% on the last click of throttle. I can feel this come in on a 45 deg downline when adjusting the speed as well. With too much mix I find that these 45 lines tend to wander more than without the mix.

Just my setup.... YMMV.
Old 06-08-2006, 09:15 PM
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Default RE: Expo for precision flying?

I like PeterNZen's answer and mostly agree. I feel like to much expo, especialy on Aileron will not let you hit a constant roll rate everytime. The more expo, the farther out in the stick you will have a "knee" where it will be too critical to hit that exact spot, a little short, the roll slows way down, a little past, the roll speeds way up. I set my ailerons to the fastest roll rate i would need or want, and then about 5 to maybe 10 percent expo. On elevator I use about 20%, for rudder around 25 to 30 to make those nice corrections that the judges cant see (hahaha)
Old 06-09-2006, 12:56 AM
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Default RE: Expo for precision flying?

OK guys, everyone is talking about very small throws for prescision but how about snaps? I find it amost impossible to perform a nice crispy snap roll without having a little bit more throw. So, do you switch modes during flight? 'Cos I don't particulary like switching during sequence.
Old 06-09-2006, 05:05 AM
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Default RE: Expo for precision flying?

It is a feel thing individual to each pilot. I know a few top pilots and different ones vary from 20% to 80% expo.

fredo, I use one flight mode for precision flying and another for snaps/spins. The third is maxed out for 3D. I use the snap/spin mode for landing.

Again, a very individual thing, the above set-up works for me.

Alan
Old 06-09-2006, 06:05 AM
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Default RE: Expo for precision flying?

Thanks Kiwi, make sense what you say.

Viliam
Old 06-09-2006, 09:22 AM
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Default RE: Expo for precision flying?

Play with the rate switches but if the CG is correct you shouldn't need to increase elevator just rudder and aileron. If yu use too much elevator it will just get buried in the sanp.

Shawn
Old 06-09-2006, 10:24 AM
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bdunsire
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Default RE: Expo for precision flying?

I do known that some 'brand name' IMAC / pattern guys rely a lot on different rates / modes for different figures - switching even during a figure in some cases. Real examples, from this year's Advanced: - higher rate rudder for a stall turn, then immediately to lower rate for down-line snaps; or higher rate elevator entering a spin, to lower rate elevator at the break (the break being done with a rate change switch).

While it makes sense to me, I tried it for a while, but I always managed to have the wrong rate at the wrong time - downline snap with large rudder throw results is scary snaps (to me at least, since I tend to fly at the low end of speed ranges) - so I 'settled' (for this weekend's contest at least ) on a single rate for everything. I will, as a result, have a bit less rudder and aileron than 'ideal' for some figures, and a bit more for others - yes, the old thumbs should be able to handle this, but ...

Cheers,
Bob

(heading to Wenatchee in a few hours - oh boy!)
Old 06-09-2006, 10:33 AM
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Default RE: Expo for precision flying?

Bob, I try to keep everything on one rate for all IMAC flying. The only exception is during the stall turns; if I feel that I won't have enough rudder to get the plane over cleanly, I'll switch to high rate just for the top of the hammerhead, then immediately go to low rate once the plane is heading downhill. Have fun at Wenatchee - it's a great field to fly from.
Old 06-21-2006, 01:27 PM
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Default RE: Expo for precision flying?

You have all completely missed the always effective - Beer Expo!

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