Throttle curves

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Home › ✈️Aircraft › 🚁Helicopter › Century Radikal G20-30 N640 Hawk Predator › Throttle curves

06-18-2009 03:19 AM 11 years ago

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0Post 1

denheli

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aurora,co

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Throttle curves

Looking for a bit of help on setting throttle curves for my Freestyle.
Doing mild 3D, flips & rolls.

Looking for idle-up 1 & 2 curves
ThxAlways Learning LOGO 400 V-bar, TT R50 V2 Blue, RJX Xtreme 50, Vibe 50N, TZ Frenzy 50.

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06-18-2009 05:54 AM 11 years ago

0Post 2

Furious Predator

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I am assuming you are not running a limiter or governor.

100% at low, about 60-70% in the mid (change mid to adjust the rpm at hover) and then 100% again at the top. you will get a 'V' curve. turn on expo to make it smooth. activate a little aileron - throttle , and elevator - throttle mixing to help maintain rpm when you flip/roll it.

this should work just fine, but be aware that suddenly unloading the disk and going into a dive could result in over speed conditions.

a rev max comes in handy.Shawn
Team Leisure-Tech
Team HelixRC

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06-18-2009 06:22 AM 11 years ago

0Post 3

Git

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Brunei

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for my non governed heli using an os50, i use

normal - 0,35,70
idle up -80,60,80

nice headspeed similar sounding to what i normally use.. 1800-2000rpmAlees Rush 750

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06-18-2009 04:51 PM 11 years ago

0Post 4

Furious Predator

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how come you dont go to 100% at the high ends? are you not using full pitch?Shawn
Team Leisure-Tech
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06-18-2009 05:10 PM 11 years ago

0Post 5

Git

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Brunei

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max pitch 12, 0 centre all flight modes. if i use 100% at the ends, the head speed at hover would be around 2400 and it would overspeed too much during no load moves.

i dont governed my normal modes even on my governer equipped helis 50 and 90.. if my tuning is spot on, 0 bottom 35-40 mid and 75-80 top usually gives me a linear acceleration from idle to my normal flight headspeed. i used this method to tune all my engines.

just my two cent, i dont think the governor needs to go to 100% open at all. but nevertheless i set my governor from 0-100 just in case

Alees Rush 750

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06-18-2009 05:16 PM 11 years ago

0Post 6

imnxtc

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Git

What 50 heli?

The Freestyle is a 90 heli.

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06-18-2009 05:16 PM 11 years ago

0Post 7

Furious Predator

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i have always ran 100% at top and bottom. if the motor over speeds in a hover, i drop down the mid point as this has more of an influence then the top end.

since you are only running up to 80%. if you dont already, it may be worth while to use that aileron - throttle , and elevator - throttle mixing to give you a little power boost through the maneuver.

I'm not sure what radio you have, but i believe its pretty much a standard mix that is preprogrammed in the radio.Shawn
Team Leisure-Tech
Team HelixRC

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06-18-2009 05:48 PM 11 years ago

0Post 8

oldfart

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Vancouver, Canada

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A couple of points:

1 - It is always best to set up your pitch and throttle so that they use at least 100% ATV's by using different servo arms etc mechanically. This insures optimized use of the resolution of your radio system.

2 - A good way to set your head speed without a governor is first to insure that your mechanical set-up is optimized. Make sure the throttle barrel opens completely at 100% and that it is 1/2 open at 50% and closes enough to stop engine at fully closed.

Then, assuming you have a pitch curve that is set for 0 degrees at half stick, set a pitch curve in normal mode for 0,0,0,+5,+10 and a throttle curve of X,25,40,65,100 (X is the number required to keep it idling)

As we all know, a heli will not fly at 0 degrees, so we can now find the throttle setting, at 0 collective (mid-stick), that will give the rotor speed we want. To do so, take the heli, start it up and bring the throttle to half stick, (Note: it does not come off the ground because it does not matter what the rotor speed is, it only has 0 degrees of pitch, so it cannot fly). If the rotor speed is too low here at mid stick, bump the mid stick throttle curve point up until it turns at the speed you want. If it is too high, bump it down until it is at the speed you want. Now you have the % number in your throttle curve that will turn the rotor at your desired speed while at 0 pitch. For this discussion, we will assume that number came to 43%.

Now, bring it into the hover, and do the same at the 3/4 (point 4 of a five point radio) stick...we will assume that came to 69%.

Now go back to the pitch curve and set -10/-5/0/5/10 into it.

Now climb at full throttle and listen to see if it slows down or speeds up. If it slows, you cannot add more throttle like the other two settings, because your throttle is already set to open completely at 100%. So this means you may be too rich and/or have more pitch then your power system can handle at that rotor speed. If it speeds up...add top end pitch until it maintains the rotor speed your desire. If it slows down, take away top end pitch until it maintains the rotor speed you desire.

NOTE: for a "pop" type of 3D setting, you can add more pitch at the top then the motor can take, but then you will have to be more careful when using it, to only do so briefly, and to have your throttle come up earlier to 100%, with the help of a 7 point curve or higher radio system.

Now for your 3D idle up throttle curve settings, mirror the bottom with the top. e.g. if now you have a 15/25/43/69/100 in normal, then set your throttle curve in idle-up mode to 100/69/43/69/100

Note: for the "pop" setting you woud have a seven point curve that would be 100/100/69/43/69/100/100.

Now you should have a throttle curve that matches all the loads of your collective system and that maintains that rotor speed throughout.

As for the cyclic and tail loads, you must now use an aileron to throttle mix, an elevator to throttle mix and a tail rotor to throttle mix to maintain rotor speeds as these loads are applied.

You will find this explained here:

http://www.leisuretech.ca/index.php...rottle_-_pitch/

NOTE: this will only work on Century helicopters

Now go out and burn up the sky

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06-18-2009 11:14 PM 11 years ago

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Silvashadow

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Like Oldfart says. Real good clear description of what works.

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06-18-2009 11:56 PM 11 years ago

0Post 10

oldfart

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Hi Silvashadow

Good to see you back, haven't seen you here for awhile.

Phil

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06-19-2009 02:21 AM 11 years ago

0Post 11

Git

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hi oldfart (haha)

i will try what u explained

just one question, when do you tune for the engine sweet spot?Alees Rush 750

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06-19-2009 05:41 PM 11 years ago

0Post 12

oldfart

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Tuning the engine is actually not all that difficult for someone who is at least competent enough to climb a heli steadily at full power, to 100 feet or so. This will insure it has cleared out any unburned fuel that could be left in the engine's crankcase, and will be running only on the fuel being fed from the carb.

With most two or three needle carbs, the BIG needle as the main one that is best used to optimize the overall mix at full load, when the barrel is fully opened. The idle screw is then used adjust for both a smooth idle, transition and the "sweet spot" in the hover.

NOTE: the YS91ST and some of the other YS engines operate a bit differently, with the BIG needle used for Hover and idle and the screw for tweaking the top end instead of the idle.

So one must first adjust the pitch for a relatively light max load, with say a 9 degree pitch setting and at a setting you know is too rich. If you are new to this, then you can start with it so rich that it will barely hover at full throttle. Then do some long full power climbs. You know you are not "overloaded" or lean, so if the heli starts to bog, then it means you are still too rich, so come back and lean out a couple more clicks. Continue until it climbs without bogging.

If you continue until it now becomes too lean, you will see it start to bog again, so continue flying back to yourself while quickly coming off max pitch (to present a lighter load and to allow the engine to stabilize) and land. Now richen the mixture slightly again, until it will pull that light load comfortably and then richen a couple of clicks more.

Now add a bit more pitch and climb again, and repeat the test. Gradually you will reach the point where you are at the most pitch your motor will pull at that head speed while having the main needle set at the proper setting.

After this, you can optimize the setting of the hover/idle screw or needle. When on the ground, and you throttle up, you do not want it to stumble, but to transition smoothly. Of course, if it is too lean, it will transition nicely but heat up in the hover. So set the screw so that it idles richly and stutters a bit when you open the throttle. Then slowly (1/16 turn at a time) screw it in until it transitions and leave it. It should now also be "sweet" in the hover.

Of course, I am talking about properly designed heli engine carbs, but a number the less popular engine brands use carbs that are better for use on airplanes then helis, so they will never be able to get all three phases (idle, hover, top end) working smoothly. To understand why you will find an explanation here:

http://www.leisuretech.ca/index.php...ps/heli_engine/

It takes a bit of time to get the engine working like a Swiss watch, through all power settings, but when you get them adjusted so they do, you can generally leave them alone and they will keep a big smile on your flying face through hundreds of flights.

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06-20-2009 04:30 AM 11 years ago

0Post 13

denheli

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What I am looking is a base line to start with. Like 100-?-?-?-100 and the same for idle-up 2.
I have copied down everyones input and thanks.
-CAlways Learning LOGO 400 V-bar, TT R50 V2 Blue, RJX Xtreme 50, Vibe 50N, TZ Frenzy 50.

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06-20-2009 06:50 PM 11 years ago

0Post 14

imnxtc

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Now for your 3D idle up throttle curve settings, mirror the bottom with the top. e.g. if now you have a 15/25/43/69/100 in normal, then set your throttle curve in idle-up mode to 100/69/43/69/100

Note: for the "pop" setting you woud have a seven point curve that would be 100/100/69/43/69/100/100.

I thought this from oldfart's post would be a pretty good baseline?

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06-21-2009 01:57 AM 11 years ago

0Post 15

denheli

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I'll give it a try, Thank you.
-CAlways Learning LOGO 400 V-bar, TT R50 V2 Blue, RJX Xtreme 50, Vibe 50N, TZ Frenzy 50.

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