450 Throttle curve

[nitro208ca]

this is going to be a hard question to ask, for the reason that my brain is asking the question faster then i can type it
I know that there is a formula to figure out thottle curve on the DX6I.
I know that everyone uses differenent settings from someone else, which is what makes this hobby fun. There is not one person that uses the EXACT setting or flies EXACLY like someoneelse...but...ALL base line/ starting points are the same (I.E -10 pitch at low stick, 0 pitch at mid stick +10 pitch at high stick.Once that is done tweek to your liking)
Now the settings that im going to use here are Just examples.
On the DX6I pitch the five points are (L) (2) (3) (4) (H). Lets say for example I wanted to set (2) at 26.5 for pitch, how would you figure out what the thottle curve for that point without taking out the aircraft and test fling. Lets say for example (3) is 58.5, how to figure out what the thottle curve should be for that point

I hope that you are understanding what im tring to say

If i havent said this before...I am a bit of a perfectionist when setting up my aircraft

(there has to be a base line or starting point to this)

 

[Tony]

I'm going to try to answer this the best I can. I think I understand what you are saying. Below is the chart of what I suggest you start with for pitch and throttle curve. It's what I started with anyway and still use most of the time.

Some people would like a flat T-curve after 50% like they are in idle up. Some people want to fly with the throttle at about 40% vs 60% where I like to fly. As you stated above, it's personal preference and you have to figure it out yourself over time.

Here is the graph of the stock setting I suggest.

P-Curve	45	47.5	50	75	100
T-Curve	0	25	50	75	100

<tbody>
</tbody>

That grid above gives you a visual idea of what pitch setting equals what throttle setting. One thing to remember is at 50%, you should have NO PITCH on your blades and that is where you would likely want to have max throttle or 10-15% less than max. Either way, you will have spooled up the blades to almost full speed before leaving the ground.

Lets look at another example where someone wants a flat curve on throttle while in the air.

P-Curve	45	47.5	50	75	100
T-Curve		45	75	75	75

<tbody>
</tbody>

As you can see in the example above, the throttle curve and the blade speed will remain constant at and after mid stick. This will not only give better performance, but it will also lock the gyro in better since the motor is not over torquing the tail.

Those examples may or may not answer your question on what each pitch should be. There is an equation that you can use however. mid stick in idle up is 50% throttle, 50% pitch (curve) but is 0º of pitch on the blade. If you have a total of 10º of pitch positive and negative, every 10% of stick input is equal to 2º of pitch. So if 50% stick is 0º, then 75% stick (25% more) and would give you 5º of pitch. Very confusing when you first read it, I know. But if you can get this down and work out the equation you will find your answer. It's easiest when you have +-10º of pitch though.

I hope this somewhat answers your question. If not, let me know.

 

[nitro208ca]

Thanks Tony
The part you were saying about 10% stick = 2 degrees pitch is the forula thing that i was looking for.I did notice that after 50% stick you leave it linier

 

[Tony]

Yes I do. If you think about it, when you are in idle up, your pitch curve is going to be linear. I like to leave everything over 50% the same from normal to idle up. Makes for a smoother transition other than the jump in rpm that will cause more lift. Some people try to remove out all pitch jumps, I just stay ready for it.

 

[nitro208ca]

now knowing that for the pitch curve.
Using the same idea 10% = 2 degrees pitch
what about the calculation for thottle curve

 

[Tony]

It works out the same. 10% throttle = 2º pitch each direction.

 

[zenmetsu]

I like how everyone does things differently, makes the hobby interesting.

I keep my pitch curves similar to what Tony has, but the exception is that my pitch curve is more like 50/47/50/75/100. The rationale? The 47% keeps a little down-thrust while spooling up and that helps with stability. Below 20%, you really aren't generating much thrust, so I bumped this back up to 50% to have the blades perfectly flat while "parked". This is helpful for folding the blades back into the blade retainers when putting the model away, and it also helps for checking / adjusting the head because you can make sure that everything is level (swash, flybar, blades).

As for my throttle curve, I won't mention all of my numbers here because they will differ for everyone. At 50% stick, I have 85% throttle, but the throttle curve above mid-stick is set so that as pitch angle increases, the throttle increases to maintain a constant head speed. Once I get into more demanding flight, this may change a bit, but I find that a constant head speed helps with stability on my 250.

Ultimately, use other people's numbers as a starting point and then tailor them to your needs. The big thing I think is to have 0 degrees pitch at mid-stick so that you have a reference point when flipping to idle-up.

- - - Updated - - -

Oh, I forgot to mention something. Having 50% at lowest stick will also remove the negative pitch when doing "emergency landings" during the learning phases. While it is true that the blades will not generate much thrust below 20% throttle as I mentioned earlier, when ditching the heli, the blades are still rotating quite fast and that -4 or -5 degrees of pitch will slam the heli into the ground. This is why I really like 50/47/50/75/100 on my pitch curve.

I've gotten into the habit of hitting throttle-cut when I have to ditch, and then stay on collective/cyclic on the way down to try to buffer the landing a bit. It is really hard, however, to avoid the twitch-reaction to slam the throttle stick down when learning though.

 

[Tony]

The problem with having 0º of pitch at low stick is when you land. If your blades are flat and a gust of wind hits the heli, it will cause what's called "Translational Lift". Even though you have no pitch on the blades, the wind could pick the heli up while it's spooling down. This is why mine is at 45 47.5 50... Should give about 2º of negative.

as you stated, everyone is different. If this is what feels right to you, by all means go for it. Just watch that wind to make sure it doesn't pick the heli up.

 

[zenmetsu]

That is a really good point. I have flown around in gusty conditions and haven't had a problem yet, then again I've had a training gear on up until yesterday. I will definitely remain mindful of this, and yeah, I learned about translational lift through my practicing.

I think I first noticed it when starting into forward flight. I used to practice by keeping the helicopter right at the point that it was about to leave ground effect, hovering about 2-3 feet up, to minimize my need to control the collective. Once I started moving forwards, ETL would kick in and she'd climb right out of ground effect and keep going up. LOL The same thing happens when you hover up a good distance and start getting into the wind. It can be a bit unnerving when you are learning to fly a heli, but knowing why something is happening is important to correcting it.