Throttle/Pitch Curves

[AnthD]

I'm just having a play round with some Throttle and Pitch curves , Just wanted to know what people are using for what and how many flight modes are people flying with , I'm using Hold at 0% for AR so was going to set up FM1 for invert and 3D .

As for the Pitch curves Ive not messed about too much with this but again some advise on set up would be great!

AnthD

[Grumpy]

It's a personal thing.

Me, i use the same pitch curve on all flight modes. I fly with the 'standard' 3D pitch straight line curve of 0%, 50%, 100% (giving -12, 0, +12 degree pitch range). I use the same curve so that I don't get any sudden change in pitch when I change modes, but also so i don't get absent minded and try to fly inverted with a pitch curve that does not have enough negative pitch.

I'm running governed headspeed on all my helis so the throttle curves are all flat lines, something like:

• Hold: 0%
• IU1: 67%
• IU2: 75%
• IU3: 82%

Hold will always be zero but the other % values will vary according to hardware and personal preference.


A beginner might choose a different pitch curve, something that gives 'softer' cyclic response, something like 35%, 60%, 85% (giving around -3.5 , +2.5 , +8.5 degrees of pitch)... and work from there.

[Peteski]

As a beginner, I'm following John Salt's setup guide from RC Helicopters - A Super Fun & Rewarding Hobby

In short that means tame non-powered up throttle curves, e.g. 0%,40%,55%,70%,70% and a limited pitch range e.g. 0 to 9 degrees positive with a 3 deg hold for soft landings.
When using multiple pitch curves he suggests keeping the mid stick pitch values very close to prevent any sudden change when switching.
For learning loops and rolls he suggests a beginner pitch curve of -5 to +10 deg, so you can simply pull full low on the collective when inverted to avoid losing altitude.

His setup guide is well worth the $20 and discusses all the throttle/pitch curve variations and governors in detail as you progress.

[Grumpy]

Personally I'd advise never to fly on a throttle curve that starts at zero. You can use such a curve to spool up (if for some reason don't trust the ESC slow start) but you should switch out of it before lift off. Flying on one is a really bad idea IMHO. This is for two very good reasons:

1. If you ever go to full negative pitch in flight (as you might if compensating for a sudden climb due to wind gust etc) then the throttle will cut and you are into a slow spool up, so probable auto rotation / crash landing.
2. It prevents you from getting into the habit of using throttle hold to kill power. Using throttle hold should be instinctive and it wont be if you use a zero power throttle curve.

There really are no positives for using a zero throttle curve.

[coolice]

Hey Guys.

This is always a hotly talked about subject and one covered not too long ago to, which get's mostly made up of personal opinions and reasoning's behind certain ways which in all honesty probably don't exist.

Simple fact, you do not need to run the full collective pitch range in every flight mode. Personally I have never done it, still do not and never had a problem and I constantly switch flight modes in flight. The pitfall for beginners running the full negative pitch range in normal mode far outweigh any positives.
All my hovering/upright stuff is done in normal mode, when I want to go inverted I go into IU1 (full pitch range) with X head speed or IU2 (full pitch range) with a higher X speed.

A beginner does not need the full pitch range, at least not in the negative sense, I don't see a problem with the positive pitch values as it saves the pilot having to re-learn a collective pitch feel later on, but one can soften the feel using the pitch curve and EXPO functions made available to them within the transmitter.

You will never go to full negative to counteract a wind gust, if you do something else is wrong on the machine.

There will be no sudden jumps when changing flight modes if you are hovering upright and change flight modes, assuming all your pitch curves are the same from mid-stick upwards, which is advised.
The only change you will see usually is a slight increase in rotor rpm usually due to governor speed changes and thus need to make subtle changes to your collective pitch stick position to compensate. But we're not talking major changes here and a well used ESC changes head speed gradually anyway.

What is also being discussed here is conditioning of the pilot into using certain flight modes for a given flight envelope and this is good practice in the long run.

Most beginners are advised to run no more than -1 at bottom stick, this is to avoid any boom strikes should they panic in the early hopping stages and chop the throttle causing the model to slam itself downward.
With the remaining pitch curve points, I always ask where the student want's to go with their flying and setup the model based on this information.
If it's sport/scale, then a machine which hovers at mid-stick will probably be a good thing. If on the other hand it's 3D/aerobatics, then getting used to the zero centre stick pitch curve is the way to go from the outset, as you get used to the more aggressive feel of having 10+ degrees of pitch crammed into half stick movement.
Myself I change from a hovering mid-stick setup to the preferred zero centre stick probably about 6-8 years ago now, previously I'd 3D'd all my machines with them able to hover at mid-stick. My pitch curve was a sort of tick shaped affair and I was asked how I could 3D with this, the answer was I'd taught myself to.

I always take off in normal mode and thinking about this again, this has probably stemmed from my old IC days and many new pilots to the sport have come in with electric only machines so the initial take off can be dealt with differently.
However doing either way, if it works for you great, but it's not the definitive.

On my electric machines ,in normal mode I have;

-3 ~ 0 ~ +12/13 and my throttle curve (CC ESCs) goes; 0 ~ 30 ~ 30 ~ 30 ~ 30, so within 1/4 stick movement, my ESC is on it's set rpm point and doing it's thing. Although my pitch curve looks very simple, I am making use of the adjustable points made available to me by my Tx and the EXPO function to give me a smoother curve.

So I carry the model over to the heli pad, flick out of throttle hold, power up (ESC spools up slowly) and going past mid-stick the machine lifts.

Have I made a mistake and tried to go inverted in normal mode? Yeah, twice! Was it hairy? Yes! I think I swore and carried on. Mistakes can and do happen, no matter what curve you have set or use, anything could catch you out.

The throttle hold idea to kill power, again I think this comes from the electrics, as with IC machines you need to be in normal mode where the throttle trim works and allows you to set a reliable idle for the motor. Yes you can use throttle hold to do this I suppose, but it's not like an electric model where you turn the motor on & off to put it crudely.

If you are a beginner, get used to using all your flight modes, that is what they are there for. You can have your normal mode setup quite tame, sedate and calm for hovering around with and figure 8's for example, then use your IU's to give you a more responsive machine.

With pitch curves;

Beginner Normal Mode; -1 ~ 0 ~ +10, for more advanced try -3/4.
Sport IU1; -6 ~ 0 ~ +10/12
3D IU2; -10/12 ~ 0 ~ +10/12

A lot of this is how you were taught or shown by the local club expert, which then stays with you throughout your flying career and as it works for you, it's assumed it's the best method. Truth is it's probably not the best, but it works for you and so you stick with it.

Bottom line, you need to try all the options and make up the best setup for you.
.

[Grumpy]

You will never go to full negative to counteract a wind gust, if you do something else is wrong on the machine.

It happened to me. The 'problem' is that if you run a beginner friendly low pitch range with very little negative pitch, then you do in fact use most of the stick travel range, so it's very easy to kill the throttle accidentally if you just move the stick a fraction too far, which is easy to do. This wouldnt happen with i.c. power of course, but with electric it's all too real.

As We both said, a lot of it is personal preference and it depends a lot on how you learned. People who learn on i.c. will bring their i.c. setup over to electric even if when you analyse it, it actually doesn't really make much sense on electric. I think this i.c. legacy explains the 'normal' mode throttle curve advice.

I personally stopped using different pitch curves the first time I briefly forgot which one I was in and went inverted with a curve without enough negative to fly inverted. Doing that once was enough, I don't want to ever do it again. Maybe others aren't as absent minded as I am. To be honest though even if your memory is perfect, once past the beginner stage I don't see the advantage of running different curves. Why is a curve with less negative any better for sport flying? As you said yourself, you just get used to a certain curve and the response it gives, so why use different ones and confuse yourself.

[coolice]

Hey Buddy.

I think if you're going above hip/head height with limited negative, then yeah you should be running a little more. If you're that high then you're more advanced than a raw beginner and probably not going to chop the power in panic.
The only time I got caught out was when someone asked me to show them their model doing a circuit, with only 0 degrees bottom stick from memory, I made myself a cup of tea while I gently flew it down.

Apart from when I shoot an auto, I always flick back into normal mode for landing. It was mentioned recently to me as well by someone who'd followed my logic, but the reduced pitch range in the lower half of the stick travel helps you attain a smoother landing. Also when I have then landed, closing the throttle stick kills the power on electric or puts the IC to idle. No faffing with more switches or the hold switch, just land and power off.

Best thing, try all options and go from there.
.

[Peteski]

I'm not yet confident enough to run a fully powered up throttle curve, so I've been using a normal curve but with a very steep initial ramp up e.g. 0%,65%,75%,75% which helps to solve the low stick loss of power issue. I guess it's a pseudo flat line throttle! I'm using a pitch range of -3 to +9. Seems to work well enough for simple upright circuits. Again all from the John Salt guide, but I can see the logic. Once I gain more confidence I will aim to run flat line throttle curves and gradually open up the pitch range.

[scallybert]

I'm just having a play round with some Throttle and Pitch curves , Just wanted to know what people are using for what and how many flight modes are people flying with [...]

7 or 8 flight modes currently.

2 lots of 3 precision hovering modes. Three different pitch curves (head speed is governed); 'soft-med-hard'. The 2 groups of hovering modes have different FBL gains, etc. All three hovering modes have full +/- collective range.

The other one or 2 modes are stuntier. A more aggressive pitch curve; higher cyclic rates; lower FBL gains. [I find you can run higher gains hovering, than if you're zooming around.]

All have the same head-speed - reasonable but not banzai. When hovering, regular or inverted, I can switch between modes without a jump (in theory). ie the hover points (pretty much) match up.

The hovering curves have partial plateau around the +/- hovering points. You can move the end points up and down together to match them. The slope of the plateau relates to how hard or soft it is.

These are programmed on a DX9/DX18 in Sail Plane mode.

At least one person on this forum (if they were reading this), would be saying I was being a smart-**** - again...

Not entirely. My point is that there are many different ways of doing things - and some of us are more different than others...

I started inverted flying with pitch curves that were offset so regular hover was at mid-stick. It worked pretty ok, but I've now moved to zero at mid-stick. Changing wasn't a massive big deal.

One trick is that I tend to have a bail-out 'do anything' flight-mode. If you do get confused (eg start a manoeuvre with unsuitable rates, pitch-curves, etc), you can get to this on one switch; and maybe get out of the mess.

[Grumpy]

I got caught out just recently by the 'normal mode' throttle curve 'thing'.. A guy at the field asked me to maiden his Trex 500 which had a Bavarian Demon FBL controller. This controller has a bailout that when activated auto levels and adds collective to make the heli climb out of danger. I'd never used a FBL with bailout before.

So i was flying it around no problem and I thought I'd test the bailout.. Soon as i flicked the switch the heli shoots skyward and without any conscious thought on my part my left thumb goes into automatic and slams in negative to arrest the climb. Motor cuts, RPM is already low due to the bailout whacking in collective, so i'm stuck with a pretty messy low RPM auto rotation and a pretty heavy arrival (no damage fortunately).

I guess it was my fault, but without the zero throttle curve it wouldn't have happened.

[Tripler]

Having seen all sorts of mishaps at our club, (and the odd personal ones )
The main thing I've found to have, and taught students to have is a working throttle hold.
You can learn and play around with throttle curves that suite you and the heli,
But,, for the safety of other people and your self you must get into the automatic use of throttle hold.
Be safe fly and enjoy

[AnthD]

Hi Lads ,

thanks for for these great responses , learned a lot have been messing about and have customed some great hover curves in the pitch , obvisly no invert available on the baby hover ones as They are starting at like 55/60/65 so you can't really fail when doing circuts tbh ! I'm not sure if it's great for learning to fly though ! So for now I'm just learning and messing about with the curves .. But I do like the idea of a hover curve it makes good sense .

throttle Im using low end 15% to stop the spooling cut that's about it everything else is normal really , I've tonned Down the Expo slightly .

so I've got a newb Hover setup (making life maybe far to easy)
Invert
and just normal setup that's on the Spektrum but 15% low end for spooling ...

a question though when people are doing there Certificalion for flying circuts etc. Can they use what ever throttle/pitch curves they like ? Or is there a generic setting they must use to demonstrate there ability .. Just wondered :-0

AnthD

[coolice]

Hey Buddy.

No problem at all, you're very welcome.

Great, you are experimenting and coming to your own conclusions.

For me and customer models I setup, I set the Normal mode to be quite docile and unintimidating to start with, as the owner then get's used to their new model he or she can increase the response as required.
My idea is to have a sensible model which takes off and lands with minimal fuss and edginess, this allows the pilot to be sure their model is all ok before hitting the loud pedal and shooting into a more spirited flight mode.
The good thing about normal mode going to idle or power off, is that should anything happen and the model comes down, one just has to close the throttle which is the instinctive thing to do anyway.
Throttle hold is always a good thing, but does mean you have to be mentally prepared to flick the switch, which does come with experience.

Electrics can make better use of throttle hold as they are very crudely on or off, IC's require the throttle trim be used to maintain a reliable idle rpm and such things as temperature, humidity, hot & cold, all affect where this point will be, so throttle hold cannot be used in these instances on IC.

Something my father taught me many moons ago was to put my thumb over the top of the throttle stick when carry out a running model and this is something I have stuck with, even with my electrics having throttle hold engaged while I am carrying them.
In my travels I have seen many fliers being less careful carrying their transmitters with a live model, only to get unstuck at some point.

Eventually it will all become automatic and second nature to use the safest possible Tx positions for each of your individual models, genuine honest guidance in the interim will help guide you properly.
.

[AnthD]

Thanks for that Coolice ,
I have had a good read of your info and made a few adjustments thanks again for taking the time out and responding to the thread mate .

I have got normal set up with a pretty standard set up on both pitch and throttle ... FM 1 I've been getting using to switching over to making hovering a easy task when landing you could reduce the stick and it's impossible to crash basicly ! But impossible to invert as the low stick is set about 45 etc. .... The FM2 I use for invert flight something like 35/40/75/100 maybe but seemed to work well for invert as I can go full low stick and mantain a invert hover or there abouts if this makes sense !

All in in all feeling good with it all Im sure I'll make some changes just playing around with it all getting used to what the changes are doing in flight etc.

My Throttle hold Im using for Auto rotation basicly so that's that is that pretty normal ? If say using a FBL unit with a built in bail out would you just add the bail out to a flight mode there?

AnthD

[coolice]

Hey Buddy.

No problem, you're very welcome and always happy to try and help.

The good thing is you're trying and by making small changes along the way, it will give you chance to actually feel the differences these can make to the feel of the model overall. As experience is gained you'll soon settle on what works for you based on this testing.

With the bailout facility on a FBL controller, no I would assign this to a dedicated switch, it will usually be either the GEAR or AUX2 channel, depending on which channel your gyro gain is link to. You'd probably end up swapping channels around based on how easy it is to get to the right switches when flying, you're less likely to switch tail gyro gain for example, so if this channels switch was easier to get to you'd probably swap this to another channel freeing it up for use as the bailout activation.

There is another bailout option linked to the ESC on electric models, but this would be invoked by having a small throttle percentage when in throttle hold in the case of Castle Creations ESC's for example. In this case instead of 0% throttle in throttle hold, you'd set 6 ~ 8%.
.