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Sep 05, 2017, 03:32 PM
What could possibly go wrong?

Does this Trainer 60 need alterations

Hi, I built this RCM Trainer 60 from plans, been flying solo on it for a bit over a month. I've done some work on it lately and it's great except for one thing, I think it climbs too much under throttle. I think either the wing incidence needs to be increased, or I should maybe put a couple of washers under my the top bolts of my engine mounts to increase downthrust, but I'm not sure which would be right, I don't really understand the problem. The firewall has 2 degrees down-thust and right-thrust built into it. 2-piece beam engine mounts direct to firewall. I set down elevator trim to compensate but if i start from having the surface dead flat, I have to add a lot of trim to it, maybe 4 or 5 turns of a 2-56 clevis, or at least half the travel on-screen of an Aurora 9X trim for elevator. It just seems like far too much to me.

OK so if you were flying this powered trainer level and at constant speed, then increased throttle, it climbs, but I think this one climbs too much.A very good pilot did a test flight of it, and he said the same thing, too much climb, and suggested increased down-thrust. But I think the incidence might be a little low, you're supposed to build in 1/16" at the LE above horizontal wing line there and I wonder if mine's a little low. I can easily put weather strip on the wing saddles on the front 1/3 or so, but I would appreciate some help with this, I don't quite understand the effects of either AOI (relative to hotizontal stabilizer I guess, which is at 0 deg. to the plan's horiz.) or increased down-thrust, specifically why do I have a lot of climb under throttle. This model also does have a higher sink-rate than most trainers, it's higher loaded and a symmetrical section wing so it isn't high lift, but it does come on down quicker than most. Unlike the club trainers I don't have to throttle down until after the last turn to land. I don't mind it, but I wonder if I built it wrong. Any help understanding this, or if that really is the cause of the problem (ie. excessive climb on throttle) I'd appreciate. Thanks
Last edited by BernardW; Sep 05, 2017 at 03:55 PM.
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Sep 05, 2017, 06:35 PM
B for Bruce
BMatthews's Avatar
You're running into a side effect of running with a somewhat forward CG and resulting wing to tail trim angle that occurs when you trim for slow level flight or a reasonable idle/glide.

The first fix is to add some downthrust. But as I recall the Trainer 60 is already set up with a fair amount of downthrust.

The other solution is going to sound bass ackwards but it's the better and "proper" way to fix this trim issue. What you want to do is shift the balance point back a little at a time. Like 6mm or so for steps. At each new balance point re-trim the elevator for a quarter throttle level flight trim. Then power up and see what occurs. With each step back and re-trimming of the elevator you should find that the tendency to nose up becomes less strong.

Note that moving the balance back will increase the nose up tendency with power until you put in enough down trim in the elevator. The two steps go hand in hand. With each step back with the BP input 3 to 4 degrees of down trim and be ready for more at takeoff if needed. Like I say, it seems bass ackwards. But with each completion of the re-trimming due to the BP shift things will be a little better.

Like I said, this seems backwards but as you move it back in such steps and re-trim you will get to where the model is a joy to fly and is still stable enough in pitch to serve you well for continuing your training.

You see.... the model trim cannot tell the difference between more speed from an accidental dive induced by a newbie mistake and more speed due to more power. So it responds to either by raising the nose strongly when trimmed as you have it trimmed now. What you do when you move the CG back and re-trim the elevator is to reduce the strength of the response by the model to an increase in speed.

Do NOT mess with the wing. You asked about raising the LE. That will only make all of this worse. Mind you it would also serve to increase the downthrust angle slightly as a side benefit..... but the INITIAL effect will be to make this whole nose up with speed or power even worse.

The model has the same lift as any other model of the same size and weight. If it didn't it would need to fly faster. And it doesn't. All of these traits are often credited to the wing airfoil. But in reality they don't have anything to do with the wing airfoil. I can trim a model with a Clark Y airfoil to be dead nutz neutral in pitch trim and not show any signs of all the woes that are commonly blamed on models with flat bottom airfoils. And the same in reverse goes for symmetrical airfoils. I can easily mis-trim a model with a symmetrical airfoil such as your model and folks would blame how it was flying on "that darn flat bottom airfoil". Yet it's all down to the balance point location and the associated elevator trim needed to fly level at a lower throttle setting.

Now IF you find that you still have a lot of up trim in the elevator ( as when compared to the fixed stabilizer) even with the balance being moved back about 15 to 20mm THEN by all means shim up the leading edge of the wing by 3'ish mm and move the elevator down a little to compensate. But I doubt that this will be the case if the model is built anywhere near to plan.

As you shift the balance back and re-trim you should fly a few flights at each position. Or at least after the first couple of steps where you notice some significant difference. If you're far enough along you will likely find that the model seems "smoother". That's because you're learning to fly the model and it's not fighting you by always trying to "balloon" out of turns or otherwise strongly nose up each time you mess up the turn entry and exits or don't notice a slight dive. Don't take this for granted though. You still want to maintain a keen eye on the model and learn to smoothly enter and exit the turns with well coordinated elevator inputs so the model seems even smoother than it is.

If all this makes it seem like the angular relation between the motor, wing and tail and that angular relationship with the balance point is somewhat complex and that each angle relies on all the other angles and balance then you are right. I hope that all the explanations above help you to see a little of the "why" as well as the "how".
Latest blog entry: Garden Gliders
Sep 05, 2017, 07:07 PM
What could possibly go wrong?
Originally Posted by BMatthews
What you do when you move the CG back and re-trim the elevator is to reduce the strength of the response by the model to an increase in speed.
OK I can understand in those terms that it should respond how I want it to if I change the balance point and re-trim. I did have the CG forward to the front edge of the spar, when the plans suggest a little back of that. I have shifted the battery since it was set up for me that way, but not by much and in fact I need to measure it properly again as I've tinked with it a bit lately.

What feels funny to me, though, is that I already have to use more elevator trim than I feel comfortable with. It's stick-forward or elevator down now, enough to see it at a few degrees down from the h. stabilizer maybe. Is what I want really to have even more? It won't add enough drag to care about? I just would have thought a well-built model, assuming the design isn't full of errors (I doubt this one is) would be designed to fly with -no- control deflection, at some speed. Or is that speed for this model much lower than I'm trying to fly it, maybe. My impression of this design is that being an advanced trainer you don't ginger along in it, it's much easier to fly with a little airspeed up. It just seems funny to me to have to wind in all this compensation on the elevator just to fly straight... but if that's how they work, fine.

Yes the plans for the Bridi/RCM Trainers of this size do show 2 deg. down thrust, and 1/16" at the LE. I should try to measure it properly and see what I've got. I did, but now I'm not so confident I got it right. I appreciate your shedding some light on this for me and will try as you suggest. First of all then I better sling up that Vanessa rig and see where the CG is currently. When i did this when I first built the model it came out right on the mark shown on the plans for front of the range. I took it to a club and the instructor there checked it, and first thing he said was CG should be further forward, so we added 30g of lead by the engine and then he was happy. I've moved the battery back maybe 15mm since then, actually come to think of it as I overhauled the front end recently the battery is now more like 20mm from the firewall when it started right up against it. I'll try your process and add enough down elev. to trim it how I think it should be at the speeds I usually fly, and see if the response is better. As you say I'll do that over a few flights and get a chance to get used to it before I decide if it's right. Thanks again.
Sep 05, 2017, 08:29 PM
Closed Account
First step I would suggest is to carefully check the CG position. If it is off, move the battery and/or add ballast, then fly and see if the problem is fixed.

Next is to check both the wing and tail incidence angles using an incidence meter or level. The difference between the wing and horizontal tail incidence is what sets the trim speed (actually angle of attack). If it is off, you can correct it with either surface.

If the problem persists you can gradually move the CG back as BMatthews suggests. Keep in mind that this will reduce the pitch stability of the aircraft. The airplane may lose the tendency to climb with power, but you will have to fly it all the time to keep it on speed. This is fine for an aerobatic airplane but may not be desirable for a trainer.

If you have a programmable transmitter, another thing you can do is mix in a little down elevator at full throttle. This leaves the speed stability in place but reduces the climbing tendency. If you try this, start with the smallest amount of mixing available (maybe 2% down elevator at full throttle) and work up from there. As with any new mix, put it on a separate switch so you can experiment with it in flight at a safe altitude.
Sep 05, 2017, 11:46 PM
B for Bruce
BMatthews's Avatar
I'd agree that it's wise to assume nothing until checked and that the method used to check angles between wing and tail is itself checked to be sure you are seeing what is truly the case. Then compare to what the plans call for.

I know some folks obsess over having the elevator sitting in line with the stab. But other than one particular trim speed this will never be the case anyway. So do what is needed to get it to fly the way you want it to fly. It the amount of down trim in the elevator becomes excessive, such as 15 or more, and if the plane flies the way you like at that setting then consider surgery to alter the stabilizer angle so that it's closer to the line from stabilizer leading edge to elevator trailing edge. This may not seem right. But if it makes the model fly as you wish then just assume that you are not at the level that the model was aimed for. Instead you've gone beyond that point.

....The airplane may lose the tendency to climb with power, but you will have to fly it all the time to keep it on speed.......
I totally agree. If taken to the ragged edge then this would certainly be the case. But given the description of how it's climbing strongly with power I'd say he's a long way from approaching neutral stability.

I'm currently flying three new to me models. A Pilot Stinson Voyager, a yellow crazy aerobatic fun fly model and an E-Flite PT-19. The Stinson is already balanced behind what the manual calls for but it's still crazily positively stable. When trimmed to fly level at a nice slow but well over the stall speed it will go vertical at full throttle and dives like a stone if I cut power. Certain signs of a grossly CG forward condition in my book. It's not just a downthrust thing either. It also pulls out strongly if I do a dive test from a low power tickover slow level flight. All signs of a too strongly positively stable model. I've got a new lighter motor on the way (it was also ridiculously over powered with an E-Flite Park 480 and extended the battery mount tray to allow me to shift the pack more to the rear.

The aerobatic model didn't come with a book so I guessed at the CG on the conservative side. And after a couple of test flights it's now apparent that I need to shift the CG back a good 5 to 7% to get anywhere near neutral stability. Only the PT-19 was found to be nicely stable without being too strongly stable when the balance was set to the rearward position called for in the book.

I long ago cake to realize that pitch stability in our models is very much like Goldilocks and her porridge temperature....
Last edited by BMatthews; Sep 05, 2017 at 11:57 PM.
Sep 06, 2017, 03:10 AM
What could possibly go wrong?
Originally Posted by BMatthews
When trimmed to fly level at a nice slow but well over the stall speed it will go vertical at full throttle and dives like a stone if I cut power. Certain signs of a grossly CG forward condition in my book....
Ahh! Dives like a stone, eh? Well that's Part II of what's going on with this model. My model sinks faster than any other trainer I've tried. I actually *like* that it does that, but I was starting to doubt if that's the designer's intent. It's still a trainer after all, they're not usually like that. The instructor who set it up did move the CG quite a bit forward, I could just about remove all the ballast, put the battery back up front and start from there. It was definitely forward of the indicated position on the plans... that might be what's going on here. I don't mind so much if it loses a little positive stability, I'm through basic training as far as I'm concerned and into the Let's Have Some Fun stage. This is all about exploring what happens when you DO explore the CG away from the starting position, and making it stall just so I know what to expect when it does, so by all means I'm more than happy to alter it.

So that sounds like a good starting point. I'll sling it up in the Vanessa rig today and see what I get, but I'm pretty sure I'll find the CG is still ahead of the design range shown on the plans. And then I'll fly it again and see what happens. This sounds like the most likely explanation so far.

Thanks for the input, very helpful, and I'm grateful. I'll report back as soon as I get a chance to try it out once it's re-set, that should be Sunday or soon after. That's great, I was hoping for something that would ring some bells and that sounds like both Bruce and JRuley see the same reason for my problem, and can explain why. Cool! Will get back to you.
Sep 06, 2017, 11:03 AM
B for Bruce
BMatthews's Avatar
I was only half joking when I mentioned the parallel with Goldilocks.

When we set up a model with a very strongly forward CG it can behave like this so badly that it becomes difficult to fly. And all the downthrust we put into it to control the effect during added power still leaves us with a model that responds to diving with a strong nose up tendency. Even on a trainer this makes it an odd model to fly with odd quirks if one does not realize the root cause.

So that well intentioned instructor didn't actually do you any favor when he adjusted the balance to be more forward than it showed on the plan.

I also do not want to make it sound like I automatically set up all my models to fly very close to neutrally stable. Far from it. I actually like a well tuned amount of positive stability in most of my models as it reduces the work load on the pilot in many ways and allows flying out further away with a higher amount of trust in the model. But too much of a good thing is just as bad as not enough.

When I dive test a model from a glide or low power level flight setting I look for a recovery path that sees the model pass through level after a 40 dive that requires roughly 15 to 20 wingspans of the model worth of height. I don't worry about the nose up zoom that occurs after that. Just the initial first portion from dive to level of the hands off recovery. For a model used for training I might sharpen this to more like 12 to 16 wing spans which would be the tightest I'd want to go. Models that would rotate from the dive through to level and on in a shorter distance would have more bad features than I'd want. And even at 12 spans I might find it annoying even for teaching and aim more towards the 15 spans. But that would depend on the actual model and how it behaves in flight.

So a 5 foot model set up for training should rotate through level following the stick release in around 60 to 80 feet. And for sport flying I would prefer that to be more like 120 feet give or take.

Models intended for more aggressive aerobatics I set up to be right near neutrally stable and want to see a dive test that shows little or no sign of even rotating the nose upward. Mostly I'm checking to ensure that they don't want to tuck to a steeper dive. Flying aerobatics with this sort of trimming is a pure joy. The models go right where pointed.

The work load on the pilot with such a model isn't as bad as you may think. It's no worse than the steering nudges we use when driving a car down a straight road. Neutrally stable does not mean the model is constantly trying to turn around and fly tail first. In fact flying a flat foamy flippy flyer at some degree of negative stability to make it easier to hover and harrier proved to be no worse than driving a car on the highway in a moderate cross wind for corrections needed to keep it pointing where desired.

If all this makes it sound like setting the CG to suit how YOU fly and somewhat to suit the model is a powerful and basic trimming tool then I've done my job. Because it certainly is a core feature of trimming our models to fly the way we want them to fly.
Latest blog entry: Garden Gliders
Sep 06, 2017, 11:46 AM
What could possibly go wrong?
Thanks Bruce, much to consider and all excellent information. I am doing ok at RC so far but I still have a lot of experience to gain, for example understanding what to expect when I make certain changes to the model. Centire of gravity for instance is exactly what I need to try and understand better, also the relationship between thrust, incidence and the other measurements that determine so much about its behaviour. This is basically a great little model and I love it, I just really wanted to get it set up better and I think this is the heart of the problem. It does have these characteristics that have been a mystery to me, basically over-reacting in pitch to just about everything. This would have to be affecting turns too, which I find hard to get just right, like I felt I could do easily on certain other models. With this one you've really got to time everything perfectly, I rarely manage a gentle controlled turn without gaining or losing altitude no matter how careful I am. I was given a shot on a trainer called a Jackeroo and I could turn it dead flat all day, so I knew there was something different about this one, without knowing what it was.

The question of tuning stability in these terms is new to me, too. I think if I want to be a better RC pilot then at some point I'm going to have to hit the books to better understand how a plane really flies, more than you usually get anyway ("this pointy arrow is called a vector, and also there is this stuff called lift and unless you buy enough of it wearing drag your plane falls out of the sky like a graph of the GFC, which is why we call it a budget" etc.). I do have an old model aircraft aerodynamics book, wow it's been 30 years, wonder if I can still find it. At least you've got me looking in the right direction for a solution. So no, the model doesn't need any alterations but shifting the battery, from everything I've read here.

I really appreciate this, thanks! I knew there was something I wasn't getting and I think this sounds like it. Awesome.
PS here is a test pilot from a pretty good club doing a test flight of this model before I started my tests to allow me to fly solo. You can hear his comments on it during the video, he does seem to find the forward CG to his liking, I guess it's maybe different for different people. To my tastes it's too reactive... so I have another question, right now does this mean I find the model too stable, or not stable enough, causing this climb and sink characteristic that I think's too high? Thanks
Sep 06, 2017, 12:45 PM
B for Bruce
BMatthews's Avatar
I won't say it won't help. But a driver doesn't need to understand about combustion chamber pressures or oil technology to drive a car. And you don't need to learn all the nitty gritty to trim and fly a model.

Much of my "pontificating" above is to give you some reasons why this works. Because if I simply told you to move the CG back and re-trim the elevator you'd look at your computer screen in a funny way. Which is why I offered up the sordid details of "why".

Once you experiment with THIS model you'll have a feel for the results and can apply them to other models.

Oh, a side effect of moving the CG back is going to be that the model becomes more sensitive to elevator inputs. You may find at some point in this process that you want to move the pushrod to a further out hole on the elevator control horn. Or if it's already all the way out to move to a more inward hole at the servo. I mention this because you might confuse "sensitivity" with "unstable" when in truth it's just the model reacting more strongly.

Oddly enough you will likely find that you prefer the model with much less pitch stability than you think you need. You're past the initial flight training so you have the skills needed to easily monitor your pitch attitude and should not be hesitant about nudging the stick a little this way or that in turns. You're likely already working hard at learning to smoothly coordinate the elevator with the bank angle in turns to avoid diving or climbing into the turns or the same at the exit of the turns. Or if you don't yet you should. Little makes other pilots nod that you're OK than a smoothly executed level turn.

And at this level you are likely going to find that you really like a reduced level of pitch stability. Like I mentioned frequently already, some is great but too much is as bad or worse than not enough in terms of making the model friendly to fly even for a newer but past novice pilot.

EDIT- I missed the blue link to the video before I typed and posted the reply above. After watching the video and what sure looks like a dive test similar to what I described above it looks like that instructor and I are on the same wavelength. Note the slow pull out that strongly resembles the "12 to 15 wingspans" of height drop at around 2:30 in the video just before he says "That CG is perfect". I'd tend to agree with him from what I can make out of the video. Note again that it's the height loss between stick release and the model passing through nose level that you're looking for. What it does after nose level doesn't matter.

That help?

Once you get a feel for this be prepared to be a resource guy for others at your field. Tuning the model this way to match the way you want it to fly really does make all the difference in your enjoyment of the model. Out of the box is just a starting point. And makers generally set up the models to balance point locations that are aimed at the beginner or lower time pilot. Even BnF out of the box models can benefit hugely from this sort of CG and trim tuning.
Last edited by BMatthews; Sep 06, 2017 at 12:54 PM.
Sep 06, 2017, 03:19 PM
What could possibly go wrong?
Thanks once again Bruce, always great to get your input. Your walking me through what's going on here is just what I was hoping for. I've always been like that, I don't just want to drive the car but to know enough about the engine to drive it better, for example. Yes I agree with your assessment that I'm past the very basics and want to explore a little, so i guess a more relaxed state of stability is the way to go. Definitely I want to use this model to learn as much as I can in general terms that will help me in future, so rather than wait for a model with different requirements and characteristics I think it's time to learn what I can from this one. I'd like it to take longer to level itself out from a dive, if I understand this correctly. It probably was perfect for a beginner's plane, now I think I want an intermediate pilot's trim. I still spend most of my time trying to improve the basics, flying circuits and touch-and-go's, but I also practice plenty of other moves while I'm up there. I'm enjoying it greatly

More sensitivity to elevator wouldn't bother me. It's about right now, I actually moved the pushrod in one hole (towards the hinge line) on the elevator for more response, if it increases once I alter the CG then it's no problem to put it back to the outer position. One reason all this came up was that I've been re-trimming after a major overhaul, I basically replaced all the control linkages and had previously totally re-built everything else that moves, all but the wood and covering. Mass distribution hasn't really changed, just certain detail fittings have been updated but total weight of everything won't be that much different to before. It's got new servos for ailerons (with new arms, mounts, rods, hardware...), nosewheel steering based on all rigid links as I didn't like the steel cable any more, and I wanted to try using carbon fibre so it's based on a CF shaft. The leftovers of that became a new elevator pushrod, the rudder linkage is still a Sullivan Gold-n-cable but it's been better anchored for less flex, same with the throttle but I've just made sure the travels match the servo match the Tx stick etc. Renewed the entire fuel system except the tank, re-packed the battery, re-routed all the wiring and replaced any hardware at all that looked at me funny. So in the end it's only going to have minor detail changes in weight here and there which I suspect should average out to about the same as before. But, I'll remove the 30g ballast from the engine bay and measure CG and adjust to suit. I missed my chance to do it this evening in the last light outside as I had to work but I'll hopefully get it done tomorrow.

Anyway I no longer feel like I need pitch stability above all else, I'm trying to fling it around some more. That's good for the type of things I need to practice to be ready for my next level of club qualifications (I'm on silver wings, basically the beginner level but for models >2kg, and practicing for gold wings which is the first time they really do examine you on the intricacies of your flight skills), as it is I think it's fighting me trying to always stabilise itself, so I have no objection to relaxing that. I've always found that this model, and really all others, fly a heck of a lot better once you start coordinating rudder with the turns, and I've been reading why that is, due to the slip angle you get in a banked turn (but never mind that for now, I just want to indicate that I'm still learning, but I've come some way since I started and got my solo wings).

I'm sure you're right that the designers tend to go for a conservative, easier starting point with CG. That's why they give a range, not a single "best" position. That instructor in the video did set it up as he recommended and we saw that it was just where he was trying to set it, but it did catch my eye because I knew that was forward of the range shown on the plans. I think it's time to make sure it's back within that range.

I'd never considered, nor even heard of, measuring the pull-out in terms of wing-spans for turn radii, that sounds like a good way to go. So, this model has a 64" span, if we say I don't want it to level out so fast then I choose your suggested upper number of 20 spans height loss from a 40 dive, then that's ~106 feet, call it 30 - 32m. That I can estimate, and it would be a lot gentler than it's doing now. Thanks, that's a good metric, a useful way to measure the changes I make. So *that's* what the instructor is checking when he dove to investigate the CG setting, I guess. Now I can do that myself armed with this new knowledge. Great stuff.

As before it boils down to needing to measure my CG position as it is now and possibly adjusting it. I thought ahead and installed a nice long velcro strip to mount the battery anywhere fore/aft in its compartment so it's easily adjustable. I'll start by removing the ballast at the nose and putting the battery right up front again, that's how it was when I first measured it and it came out exactly on the front of the range shown in the plans. As I understand it, a Vanessa rig is sensitive enough to give me a reliable measurement so long as I use it properly, and that means I need a good horizontal datum line through the model. The top rear fuselage deck (from rear windscreen to start of vertical fin) is flat and horizontal and serves well for that measurement. I use a very small builder's line spirit level and a chunky, sharp proper plumb-bob and that should be good enough.

If this makes the difference I'm expecting to see then I'm really looking forward to trying this out next flying session, which looks to be the day after tomorrow. Even when conditions aren't great I'm really enjoying every day I go out to fly it, it's a great pass-time and very rewarding. The model's been great so far anyway and taught me so much since I started soloing on it, above and beyond what I learned in lessons with an instructor. They can really only teach you to be ready to teach yourself, and I'm trying to make the most of that now. I practice for long hours at home on a simulator, that's been the best money I've spent in RC, no doubt about it. I use it as a training aid and not a video game, rehearsing things I want to try or need to work on. This is a quite windy place to fly models so you need to get used to that or else lose most of the available flying days, so lately I've been flying quite a lot in windy conditions that many wouldn't go out in. That means even more demands for pitch control... OTOH, I figure if I get used to it on days like that, there are many more flying days open to me than if I require almost still conditions. You're just not going to get that much here, it is the world's 3rd windiest capitol after all. So a properly tuned model is going to be all the more important. *Now* I can finally tackle that armed with the information I need, thanks so much! Should make all the difference. I look forward to reporting how it goes.
Last edited by BernardW; Sep 06, 2017 at 03:26 PM.
Sep 06, 2017, 03:24 PM
Registered User
richard hanson's Avatar
You may find that one of the better stability Rx on the market, will give you a better windy weather feel
I learned Rx flying when there were no tx adj except trims and have tried most of the stability Rx on the market.
Spektrum has some of these which I like as doesLemon.
My favorite is the first one spektrum introduced a few years back, in model called the visionair.
These are cheap on the market because they require more than a first grade education to set up.
Last edited by richard hanson; Sep 06, 2017 at 03:31 PM.
Sep 06, 2017, 03:47 PM
What could possibly go wrong?
Originally Posted by richard hanson
You may find that one of the better stability Rx on the market, will give you a better windy weather feel
I learned Rx flying when there were no tx adj except trims and have tried most of the stability Rx on the market.
Spektrum has some of these which I like as doesLemon.
My favorite is the first one spektrum introduced a few years back, in model called the visionair.
These are cheap on the market because they require more than a first grade education to set up.
I'm not sure I follow, do you mean the receiver has some sort of stability sensor on board and can correct your model's trim in flight? Something like a gyro maybe? I am interested in that, though first I want to learn to do it "the hard way", all manually and with mechanical adjustments, so the model has the right behaviour built-in. Even if I achieved that through an on-board system, I think it's important to do it by understanding the underlying issues, in this case I think that must be the CG position. But thanks for the suggestion, that's something else I should find out about. Can you suggest a particular Rx and I'll look it up, and see what stability features it has. Thanks.
Sep 06, 2017, 04:03 PM
Registered User
richard hanson's Avatar
In the radio forum, there is a thread ,new today by Jim graham, titled as3x
Honestly this was a surprise to me.
Lemon also supplies full info on their selection of stabilizing Rx
There are a jillion Rx today which have built in stability because all the quad copters, all of em large or small require em.
But beware man of these are set up to work in only one fashion and can not be reprogrammed or adjusted for models other than a particular one.
A cheap one on eBay may not be a programmable one
Buyer beware.
Sep 06, 2017, 04:15 PM
What could possibly go wrong?
Thanks Richard, I don't really think I can manage to buy different stuff right at the moment, work has been really bad this season and I can only just get by, I had a couple of things I wanted to get for my RC activities but that's used up about all the budget I can come up with. But, I'll be needing at least one more Rx later for some models I've got in mind to build so I will check out your suggestion. Thanks for the tips.
Sep 06, 2017, 04:21 PM
B for Bruce
BMatthews's Avatar
Yep, the stability thing acts like a gyro. But a solid state one. And yeah, it can make an unstable model behave like a stable one. And it might even make an extra nose heavy model behave more like a "just right" setup. Not sure on that last one.

While I can see using these stability Rx's for windy days when flying smaller size models I don't really see it as a big deal in this case. We're talking about a .60 size model after all. At that size it'll handle all but the worst turbulence. And by that time your field box is likely needing to be staked down to keep from blowing away. So prudent folks would have gone home by that time.

On the other hand I can see such options as being a valuable thing on smaller models that would otherwise be tossed like a stick in a stormy sea. And as mentioned the current state of quad copter flying would be impossible without this feature working in all possible axes.

Me? I'm an old curmudgeon on the issue. I prefer that my models react as I expect them to react even in rough conditions and I'll deal with it myself. But that's how I was trained and how I prefer to continue to fly.
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