Throttle and Pitch Curves...

[12oclockhigh]

I am finding that my real heli is not responding as the sim does. I am used to the sim and find the actual radio needs additional collective that I am not used to providing and the aircraft drops like translational lift. No, I don't think what I am experiencing is all as a result of a loss of translational lift. I am going to post the curves below. I would like comments if you think the radio or the real flight curves need to be changed. Flying a Dx6i radio, 450 clone against the Trex 450 v2 from the swaps.

Normal Settings; (not stunt mode)

-------------- L ------- 2 ------- 3 ------- 4 ---------- H --------
Throttle--- 0.0% -- 65.0% -- 85.0% -- 95.5% -- 100.0%
Pitch----- 40.0% -- 40.0% -- 50.0% -- 75.0% ---- 95.5%

The question is really which throttle/pitch curves are more typical of what most guys fly? One has to be a standard against which I adjust the other.

[Chris McVey]

Throttle/pitch curve in your radio:

Your pitch curve should be perfectly linear, 0, 25, 50, 75, 100, this should give you the exact same amount of pitch both positive and negative. Example -10/10

If it does not, your mechanical set up is incorrect.

Your throttle curve should be as close to linear as possible giving you the desired head speed at hover in normal mode. This is effected by motor type, battery size and pinion.

In idle ups, your throttle curve should be a small V or stright line. Example. 80, 80, 75, 80, 80.

If you look at the sim the 3D helis are set up this way. A scale or sport heli will be set up different.

[12oclockhigh]

Thanks Chris, just exploring here...

Of course, I can match the RF throttle and pitch curves... but it might just be that I want to change the RF curves to match my radio setup.

I was wondering what other guys were flying... the guy that set this up is quite experienced and it flies right....

Hey guys, show me your curves... sorry :D

[td9cowboy]

Are you flying in stunt mode on the real heli yet? The reason I ask is that the numbers that you choose for normal mode are directly related to your stunt settings. All your normal mode settings are used for is to allow you to throttle up and down for take offs and landings. Also what you are trying to find is that sweet spot at hover that matches the same sweet spot in your stunt mode curves when you flip the switch. If you don't get it right, your heli will jump up or down when you flip the switch. Could possibly cause you to freak out and crash. Other peoples numbers won't help you much with your setup, those are just the numbers that worked for their heli. Your numbers look good with the exception of your number four setting on throttle. I would change that to 92.5 to make it linear between 3 and H. Also the top number on the pitch curve should be 100 to match your stunt pitch curve. Other than that it will fly, just don't know what's going to happen when you flip the switch :D

I forgot. that 40--40 on your pitch curve is just to lighten the damage in case you have a tendency to slam the stick down if you get into trouble. You'll only be going in at -3 instead of -10

[12oclockhigh]

Thanks cowboy for that explanation of the 40-40 I am getting ready to do some inverted work on the real heli today... I plan to have my guru available....

I also will fly the blade 400 doing flips and rolls first because I don't care about that heli crashing. It has already been fixed many times until I learned RF was a better way to learn helis.

Here are the Idle Up Settings;
Stunt/Idle Up Settings;

-------------- L ------- 2 ------- 3 ------- 4 ---------- H --------
Throttle--- 100.0% -- 95.0% -- 90.0% -- 95.5% -- 100.0%
Pitch----- 0.0% -- 25.0% -- 50.0% -- 75.0% ---100.0%

So that looks fine to me.

[td9cowboy]

Now I can see what you're doing. That looks good. If you are going inverted I can assume the transition with the switch is good. I have found on electrics, a flat throttle curve in idle up works best for me. That way you only have one variable on the collective, pitch. I run 100% across the board. You would have to bump the number 3 and 4 settings up in normal until you find the sweet spot for the transition. Keep it linear. Number 2 doesn't necessarily have to be linear, but you don't want any big bumps in the curve. If you want to duplicate your heli to the one in RF, I would use your head speed as a good indicator for performance. If you can get your hands on a tach, and a helper, get a reading in idle up at 0 pitch. Set up your RF model to the same curves and adjust the gear ratio to the same speed at 0 pitch. Doesn't have to be perfect. If you notice a big difference in roll rates, that can be tweaked with the paddle weights. It'll take a little experimenting but in the end you will have a model that mimics the real one pretty closely. If you change something on the model that breaks it and you can't fix it, just over write it and start over. Actually the CDT 450 V2 G45 doesn't require much tweaking to fly just like my real one,
it's a very good model. Have fun.

[12oclockhigh]

I like the way the EXI 450 flies... the only problem that I have, and it could be my inexperience, is the amount of collective I have to give for hover and flight. I am used to the Real Flight sticks and the Trex 450 v2.

My tendency is to back off the collective stick too much (heli drops) when coming out of forward flight too much because of being used to the sim. So I may have to just get used to it.

[td9cowboy]

I have also noticed that my realflight controllers collective stick is quite a bit closer to center in a hover than my real one. I don't know to fix that. It does make it a little closer to get from positive to negative pitch than on my real futaba radio. Maybe Mikeymike could chime in on this subject, his heli skills are far better than mine will ever be.

[td9cowboy]

Also you might want to check out your setup on the EXI. Unplug your motor, plug it in,flip into idle up,level the flybar, check the pitch on your main blades with a pitch gauge while moving the throttle stick full up to full down. You should have equal travel +10/-10 or whatever pitch you desire. If they are not equal, your swash height is mechanically incorrect. Don't forget to unplug the motor or this is going to be an unforgettable experience. Don't ask me how I know that :D

[12oclockhigh]

OK, now we are getting somewhere...at hover, my real flight 450 is almost exactly 1/2 of the full travel. On the real thing, my stick is almost 3/4 of the way up. Big difference. can anyone else confirm that, and if so, how do we change the sim's bird to reflect this?

I have also noticed that my realflight controllers collective stick is quite a bit closer to center in a hover than my real one. I don't know to fix that. It does make it a little closer to get from positive to negative pitch than on my real futaba radio. Maybe Mikeymike could chime in on this subject, his heli skills are far better than mine will ever be.

[td9cowboy]

For what it's worth, with realflight, with center stick being 50%, my stock 450 hovers at about 53%. My model with the modified pitch curves hovers at about 55%. Although I can't look at my sticks while I'm hovering the real one I would guess it to be 60to65%. Quite a bit higher than RF.

[td9cowboy]

On further investigation I'm finding that my controller is off by +12% even at calibration. In other words during calibration, with channel 3 at 0%, my throttle stick is 12% below center stick. That explains why my helis will fly in idle up at center stick when in fact they should be at 0 pitch. This could explain why our real Tx throttle stick is in a different position at hover. Could someone else please check on this to confirm my findings to see if everyone has this issue or it is just my controller that is off. Any ideas on how to fix this?

[Chris McVey]

Is this a custom helicopter from the swap pages? If so you might need to look at it's setup. Fly one of the stock heli's in the sim to compair the differance.


Chris

[12oclockhigh]

I have been playing with part weights and sizes to see if I can get the sim heli flying closer to mine... just experiments and no reflection on the sim heli... which I think is outstanding.

[td9cowboy]

Thanks for the post Chris. I think I may have found the problem. When entering the calibration screen it recommends that you center your sticks(including your throttle stick) It should read CENTER YOUR STICKS. I've been flying this sim since G3 and I did not realize that the calibration screen actually recognizes your stick position that you called center as center. Even though you are showing-100/+100 on the graph, your center stick position that you chose is center. A plane guy would probably never notice this, but it can make a pretty big difference for the heli guys. My helis no longer take off in idle up at center stick :o

[jeffpn]

Who are you calling a plane guy? :p Playing devil's advocate here, considering that three of the first four channels center themselves, what did you think 'center your sticks' meant? :D

[td9cowboy]

Hey, I was being nice, I could have said plank guys :D It never really occurred to me that as long as I was seeing -100/+100 on the graph that I could actually shift the center.DUH I bet I'm not alone :o If I miss the center mark by 10% shouldn't the graph say -90%/+110% HUH HUH? :D

[td9cowboy]

Besides that.... Where the heck were you while I've spent the last couple hours going through throttle and pitch curves trying to figure out what the heck was going on. :D

[12oclockhigh]

I just re-calibrated my G4.5 controller. It did not seem to make a difference in the collective stick position for hovering. I am hovering at about 50-55% of full movement. It is much less than the Dx6i...

I agree with cowboy... this stick position is much more critical to us rotary plank fliers. I am just trying to determine which is the proper position. I can adapt either way.

Chris, I flew a couple other stock RF helis at the hovering point... that did not seem to make a much difference. Heli Max Axe 400, Dominion 3D 90, Ecureuil (needed more collective than the others).

[td9cowboy]

12oclock, It could come down to the difference in head speed between your model and the CDT450. Mine is turning at almost 3400 in idle up. That's a good bit higher than my real one and also your EXI. That can be altered with the gear ratio. You might want to write down the stock numbers in case it flies funky with a lower head speed.

[12oclockhigh]

I will try that.... real bird is 27-2800 rpm head speed... changing from 11.5 ratio to 14.3 changed the collective a lot... now the stick is more the same as the Dx6i (if not too much), but of course the heli is a dog.

Then I would need to know the motor's max rpm too. No markings remain on the installed motor... I think that we are close to the bottom of the matter... My guru set up the heli to not be agressive and the lower head speed is requiring more collective.

12oclock, It could come down to the difference in head speed between your model and the CDT450. Mine is turning at almost 3400 in idle up. That's a good bit higher than my real one and also your EXI. That can be altered with the gear ratio. You might want to write down the stock numbers in case it flies funky with a lower head speed.

[td9cowboy]

2100 on the EXI is very low. That is probably your problem. My stock trex 450 is turning just over 3 grand with the idle up throttle at 100% straight. Ha I must have been typing while you were editing. That's better. I think we got it!

[12oclockhigh]

I changed the numbers when my guy got back to me.. you are right on about the head speed though... he plans to change the ratio in about a month... He lowered the head speed to give me more flying time. I am learning this as I go... I appreciate your comments.

2100 on the EXI is very low. That is probably your problem. My stock trex 450 is turning just over 3 grand with the idle up throttle at 100% straight.

[td9cowboy]

Glad to help, I also learned a few things :D

[12oclockhigh]

Things you don't know if you did not build the heli... but, I have learned a lot in this exercise. I think that I am going to ask for the 12T pinion sooner rather than later... I ordered some 25C & 30C "Blue" lipos today... better pricing is coming to the US.

[td9cowboy]

I'm a little partial to the "Blue" ones too :D

[12oclockhigh]

Weather around Wash DC has been lousy for a while... finally got to fly the new 30C batteries... yes it does give it more punch... got into trouble flying slow circle towards me.... had to punch out... about lost it behind me in the sun... Alls well that ends well, got it back and a nice shot of adrenaline to boot. Just fall back on what I have learned in the sim... and fly it. I felt rusty flying.

The Blue lipos had a good first day out... I can fly like an hour now without charging... too much :D :D I got the $55 Thunder AC6 charger and like it... very good price for what it does.... not perfect, but neither am I.

I'm a little partial to the "Blue" ones too :D

[opjose]

Weather around Wash DC has been lousy for a while...

Where do you fly?

I'm up at DC-RC every weekend the temp is over 50+ degrees.