dabigboy

This didn't quite see right for the radio forum so I thought I'd post here. In general, how often do you adjust trim in flight? I don't mean "trimming out" a new plane or setup, I mean routine, procedural trim changes for various flight regimes. It's my general impression that most folks just get the plane set up for one flight condition and live with it, for the most part. This is how I used to trim, but later I found myself tweaking trims a lot in-flight to get the plane tracking just the way I wanted to for that particular point in the flight. I think I started to notice it more when I started flying my Cub a lot, which changes trim more often than aerobatic sport planes, but I've found myself doing it with my Tiger to some extent also. It especially helped the Cub when I began to develop a consistent, controlled approach pattern. I'd find myself punching in the exact same throttle settings, and tweaking elevator trim on the downwind leg and final approach, to maintain hands-off pitch stability. It really worked very well, and actually mimicks the procedures I'm accustomed to in full-scale.

So here's what I'm leading up to: I'm in a dilemma on radio upgrades. I want to upgrade my aging 6ch Futaba Skysport and go to a nice computer radio. The problem, however, is it seems like all the new radios have DIGITAL trims! I've always wondered about digital/pushbutton trims, they appear to be quite useless beyond basic trimming of a new model. But then I've never used a radio with digital trim. For me there's nothing like being able to quickly snap the trim to a familiar position for a given flight regime, but perhaps this is easier with digitals than I thought. So what I'm getting at is, does anyone trim "on the fly" like this with digital trims, and if so, is it as quick and efficient as good ol' mechanical trim? Secondly, are there any modern computer radios out there with mechanical trims?

bkdavy

My Feedback: (1)

I don't trim on the fly, as you put it. I get the plane trimmed for straight and level flight at 1/2 throttle. After that its all in the pilots hands.

Most computer radios have switches for flight modes that can be programmed for things like landing mode (usually with flaps and elevator mixing) that could be used. Also, they have an accompanying beep when you adjust the trims, so it isn't that hard to know how many beeps you want to use for a particular flight mode.

Although it probably more closely simulate full scale flying, I don't find landing so difficult that trim adjustment is needed, rather than just controlling the sticks. My guess is that's what you'll find with most RC flyers.

Brad

David Bathe

If you're having to re trim flight after flight you need to discover what is causing these trim changes.
Unless there has been a conciderable change in temperature, I'd be very worried if I find I have to make even minor trim changes once my plane is set up.
It's normally means that something is wrong and I wouldn't hesitate to land straight away and discover what.

If you're referning to retriming for "that particular point" in the flight then I presume you're talking about UC up-down. Flap Up-down type related changes.
If so, a "New Radio" will make these a thing of the past as you'll be able to program certain flight conditions for different proceedures. These will automatically make several preset changes the moment to flick the Flap Switch for example. How brilliant is that?

As far as "new radios" are concerned... dont hesitate, they're GREAT. Digital trims? They're BRILLIANT.... and becasue of flight mode/conditions, you'll hardly have to touch them again.
Find out whats causing you to have to retrim your model(s) so frequently, get it sorted and get a new radio.
You'll love it.

There is one thing to think about though.
You only get what you pay for. This really applies to radios.
I've had budget sets, middle of the road do it all sets and and top of the range competition sets.
The features, quality of components and construction... and price, are directly related. If you can afford it... don't scimp.

BillyGoat

Ditto bkdavy, about flight modes and trim changes.

Cheap servos are often a cause for constant trimming because they do not center in the same spot every time.

jetmech05

I've never had to constantly re trim my airplane....on full scale you trim to counter wind conditions or weight and balance..with RC the wind conditions change so often because our heading changes several times, perhaps once a minute. weight and balance remains constant..except for fuel....
I know what you're doing, your setting up a never touch the throttle approach until threshold. triming the aircraft and watch it fly in without (or very little) input form you...
When I first started flying I tried what you do and found I was always retriming...seemed it was never right...now I trim very little...

mogman

All the cubs I've had/flown are trimmed to fly straight and level at 1/2 throttle...to descend pull the power down, to climb add power.

Jburry

Once I get'em to straight'n'level trim, at my preferred throttle setting, I then don't generaly have to trim again. To me, having to re-trim roll would tell me my wing may be shifting under g loading.

The only plane I commonly change trims on during flight is my mustang, where the pitch trim changes 2 clicks as the fuel load lightens.

J

Gray Beard

My Feedback: (-1)

Like the rest I fly my planes in without any trim changing. When I went to my new radio it didn't take long to figure out how to time my trim switches. Sort of A beep beep beep thing? I don't hear the beeps, I just know how long it takes for the trim to move when I'm holding or bumping my switches.
I could set up something like A landing mode to A switch though and hit the switch when needed for automatic trim changing?
I also haven't bumped A trim switch and knocked it out of trim in A lot of years with the new radio.

alfredbmor

A computer radio will have the same effect on trimming than a mechanical old radio, plus, if you use to have some flight conditions (Landing in example) a computer radio will be more helpful so you will never have to move your trims again, just mix some channels and choose a lever to turn on your mix. I use a computer JR radio which has digital trims except the throtle trim. I like this one. But there are now a lot of computer radios with many features that will help with your flight conditions.

Nathan King

I have a switch that programs my elevators up a little more, which I use for landing to keep the speed slow. The digital trims are fine after you get used to them. I really wish they would move faster the harder you press though.

spiral_72

Yea, I've tried that before. I didn't really like it though. I guess because I always forget to return my trims.

I think it's a little easier with a computer radio. Granted you can't just zzzzzip and trim it for the landing (or whatever maneuver) but it gives you definite amounts per click, and it beeps to the change. So four clicks/beeps on the landing approach or whatever.

I like making all adjustments with the sticks personally. I feel like the mixes and doo-dads are kinda like a crutch. Maybe I'll change, but that's how I feel now.

Do you use a strap on your Tx? The reason I ask is, if you don't have to hold your radio, your (at least mine) finger motor skills are a little better so I can feel the plane a bit more.

airbusdrvr

Most all "real" planes require some trimming in flight. I'm not aware of any that don't need pitch trim as you progress form slow to fast and back to slow. Some models need more or less pitch trim as their speed changes. An airplane is much easier to fly, if when wings level at the desired speed(manueuvering, landing pattern, etc.), it is trimmed so that fingers off the sticks result in no airplane pitch or roll changes. Why fly out of trim? Agreed, I have some airplanes that require only a click or two of up or down throughout the speed range. Others may require a little more. But the idea that an airplane is somehow set up badly if a little pitch trim is need is not correct. Also, inherent in the build of an RC plane, the wing may have just a bit or warp. This may require a bit of aileron trim correction during speed changes, also.

TFF

you will like the digital trims better as you cant bump them out of adjustment easy and once you get use to it you can count the times you hit the switch and not worry about overshooting. THe old Kraft Signature radios had the trims for the elevator and throttle at the top corners of the tx. If you flew elevator with your right hand you could keep it on the stick while trimming with the left thumb and opposite if you flew mode 1.

Nathan King

A crutch? So those airline pilots that use an autopilot tied to their Flight Management System must be complete babies that have no idea how to fly well.

I usually find that using the trim creates a very nice stabilized approach all the way to the flare.

spiral_72

Well, I didn't really intend that I fly my models with the stick held 1/4 to the right because I refuse to use the trim feature.

Nathan King

I know, just kidding. There's a few guys at our club that drive me nuts. For some purely mental reason they all trim their aircraft so that they need a little up elevator to keep it level. They say it's comforting. I say it's stupid.

dabigboy

Thanks for the input folks. I guess I should have clarified that most of my trim changes are in fact just elevator, though on my Cub I tweak the ailerons from time to time, and I believe it's due to a warped wing (previous owner/builder did a kinda bad job). I've tried to correct it but it just warps back after a few flights, so I live with it. But it's not enough of a trim change to be an issue either way.

"I know what you're doing, your setting up a never touch the throttle approach until threshold. triming the aircraft and watch it fly in without (or very little) input form you..."

Yes! One of the rewarding things in flying is when you can set the plane up and watch it do exactly what you want, with as little fighting with the controls as possible It's not that flying without trims is particularly "difficult", it's just that trimming makes it so much nicer (and I find it allows smoother and more precise flying). I've even trimmed down during inverted flight with my Tiger.....I didn't used to think trimming for this stuff was important in RC, until I got into the habit of it (and also got a feel for where my trims needed to be for various flight regimes). It makes my control in inverted flight waaaaay better when I can just nudge the stick around center instead of constantly having to hold in down elevator.

spiral_72, I do use a neck-strap actually, yeah I find it helps me a lot too. I generally rest my palms on the corners of the TX. Also I'm a thumb-and-forefingers guy (and forever grateful to the instructor who turned me on to this method), which isn't well suited to having to hold a TX...though I sometimes find myself holding/lifting the TX anyway if I'm particularly nervous.

"But the idea that an airplane is somehow set up badly if a little pitch trim is need is not correct." <Exactly.

I didn't know about the flight mode switches actually, that's good to know. Obviously I'm loathe to give up my good ol' mechanical trims, but I suspect I'd like the flight mode switches once I got used to them.....hard to beat the speed and convenience of flipping a switch. I'll definitely look for this feature while radio-shopping. There are still fine-tune trim adjustments I make at various points in an approach, for example, but I'm guessing such changes would be fine on digital trims since it's not like I need to make a lot of trim movement at once during those times. I just don't think I could ever like "beeping" my way to significantly different trim settings....would keep my attention off the elevator/ailerons too long.

I do accidentally bump my trims occasionally, would be nice to not have to worry about that. Well, thanks again for the input, I think you've all alleviated my fears that my next big radio investment would leave me disappointed with the trims. I'm sure it will take some getting used to, but it sounds like they are working out well even for those of you who trim a lot in-flight.

jetmech05

what makes this a great hobby is to each his own.....i fly thumbs some fly the pinch..neither is wrong..I don't like to trim much dabigboy does...I can fly pretty much the same approach as dabigboy using throttle...to each his own

TexasAirBoss

My Feedback: (22)

It depends on what you are flying and how you are flying it.

I had a Stafford Ercoupe. It had an enormous speed envelope. Most of the time, I would just putt around at 3 or 4 clicks of throttle. But every now and then I would open it up and fly around full throttle. It didn't look scale. It was rediculously fast. And the elevator had very limited travel. This plane did require major trim changes when going back and forth between top speed and scale cruising. It had a modified Clark Y foil. It has many characteristics of a flat bottom foil.

And I believe most slow cruisers , especially with flat bottom foils, require more trim changes.

My other airplanes are aerobats and a warbird. These planes are constantly changing speed and maneuvering. It just wouldn't be practical to constantly adjust the elevator trims. But luckily, they have symetrical foils which have very broad speed ranges and really don't require much trim changes.