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General RC Heli Discussion Discuss general topics on rotary wing aircraft, including construction, Servo's, Gryo's and Stabilizer discussions.
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Topic Review (Newest First)
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| 08-21-2010 10:19 PM | ||
| Phil Noel |
Re: 450 headspeed Quote:
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| 08-20-2010 09:10 PM | ||
| sly the dogman |
Re: 450 headspeed Indeed, changed the t-curves to 0, 50, 85, 85, 85, and no heat at all, all is at room temperature. Now that all is good I can stop testing and fly. Thanks |
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| 08-15-2010 04:06 PM | ||
| sly the dogman |
Re: 450 headspeed I don't have any problem with the delay, delay is only a matter of time, so..... I'm good with that. ( I got time, I'm retired) If I understand your explanation in your earlier post, 0, 50, 85, 85, 85, should be better than the liniar one I had. Or more or less around these numbers. The links are ajusted as the Align manual suggests for a 450 SE V2. And I hope you enjoyed yourself at the Fun Fly. Thank you for answering. |
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| 08-15-2010 03:30 PM | ||
| Phil Noel |
Re: 450 headspeed Quote:
First, without seeing your mechanical set-up on your rotor head control system, I cannot comment on the numbers that you have put into your pitch curve. As for your throttle curve - using that curve will result in a LOT of heat and head speed variation. Follow my advice in an earlier post and set your ESC as described. If your collective curve is set properly with OK degrees of pitch you will find it will fly very well. |
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| 08-12-2010 07:59 PM | ||
| sly the dogman |
Re: 450 headspeed Phil Noel, you got my attention here, I got a Turnigy 2215 that's been clocked at 4150kv, I have an 11T on it. Pitch curves : 42, 57, 72, 87, 100 Throttle : 0, 25, 50, 75, 100 Got Align woodies 325Mm A 40A ESC. The curves are somebody else's idea, a friend fix it up and put these numbers in, got a 7C Futaba I've been flying an noticed that the ESC is kinda hot. Maybe change my thr-cur to 0, 85 flat, but what about the pit-cur, keep these numbers or change ? Enough has happened, don't want to burn up the electronics. Got a 450 clone, hitecs on cyclick, futaba on the tail, 401 and s3155 Hyperion 2200mAh / 35C |
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| 08-11-2010 02:51 PM | ||
| Phil Noel |
Re: 450 headspeed Glad to have been of assistance. |
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| 08-11-2010 07:40 AM | ||
| DAVE62278 |
Re: 450 headspeed Excellent explanation!! Thanks to all for the help in setting up the curves of an electric heli. Dave |
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| 08-10-2010 01:27 PM | ||
| Phil Noel |
Re: 450 headspeed Jiver - listen to martinic and rotormonkey. The way that an electric motor uses energy from the battery, is very different to how an IC engine uses fuel through a carburator. So setting up a "throttle curve" on an ESC is very different. An electric motor always asks from the battery whatever wattage it requires to keep the rotor speed that is related to its' KV rating. (the spec that tells you how many RPM the motor is wound to turn at a 1 volt input). So if you have a 1000KV motor and feed it 22Volts it will want to turn at 22000 to be at its' most efficient. If you feed it 18 volts, it will want to turn at 18000 etc. To keep it simple (it is a little more complicated then this, but using this explanation will keep it simple), we will say the ESC changes the voltage according to the % setting in your throttle curve. At 100% it transfers it all, at 50% it transfers 50% of it and the other 50% is transferred into energy that heats up components. So at 80% it transfers 80% to the motor and only has to dissipate 20% as heat. That is one of the reasons why it is recommended, as a rule of thumb, to not run ESC settings bellow 80%...to keep everything running within temperature tolerances. Next is the constant rotor speed side of it all. We all know that the ideal set-up on any collective pitch heli is one where the rotor speed stays the same through all loads, from 0 pitch to top pitch and anything in between. So on an IC engine, the carb will have to be opened and closed relative to the power required to maintain a constant rpm as these loads change. As the electric motor will, on its' own accord, simply for more amps (current) from the battery pack as loads change, as it tries to stay in the rpm range related to the voltage fed to it. Changing the % settings in the throttle curve of your radio will only change the rpm the motor will try to turn at. So setting a curve like you suggest, will simply reslt in a much lower rotor speed at hover then it will at full throttle (assuming the battery has a big enough mah and C rating to accommodate all the power/wattage required at full pitch and the RPM that would result from full 100% voltage). In other words, if the power system used is all OK, and the full voltage (100%) will have the motor/rotor turning at 2400, then a 50% setting would have it turn at maybe 1600 (this relationship is not usually perfectly linear). So the rotor speed would change drastically as he moves the stick up and down. That is why it is always best to use the proper pinion size, relative to the voltage of the battery pack and KV rating of the motor you plan to use. The pinion selection is what will give you the proper gear ratio. One that will result in the head speed you want to fly at, when your ESC is set as close to 100% as possible. Then you can go to ESC settings in normal (for start up) of 0 (to insure your ESC initializes) 70/100/100/100 and then, once spooled up, into an idle up mode of 100/100/100/100/100 (this is what is called a flat curve across the top). If you do want a lower head speed then use 80, or any other setting between 80 & 100, instead of the 100 where I have it shown. The number you select across the top will set the head speed to what you want through all loads. If you find that at an 80% the head speed is still higher then you want, then change pinion to one with less teeth. You may find that the pinion with the lowest tooth count available, is still too hig. In that case, you will have to go to a motor with a lower KV rating. I hope that was all not too confusing, but if so, read it over a couple of times and it might all fall into place. Of Note: 1 - the smaller the heli, the higher the head speed will be required to fly properly. (that is why a heli that uses 550mm blades can hover respectably with only a 1400 rotor speed while a heli with only 425mm blades would not even get into the air) 2 - the lower the head speed, the longer will be the flights on the same battery packs. 3 - the higher the head speed, the faster will be the response of the heli. |
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| 08-10-2010 12:48 PM | ||
| DAVE62278 |
Re: 450 headspeed Thanks for the replies and help. If I understand correctly, the motor will run better running 85-90% but the 1/2 stick throttle setting seems to be 50. I guess I'm still a little a confused about this. Also what is a flat curve and is only used for a t/c in idle up Dave |
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| 08-10-2010 12:01 PM | ||
| martinic |
Re: 450 headspeed Jiver, running the motor at too low a throttle will actually cause incresed load and heat due to the inefficiency. Things will get hot quickly. It's a great way to puff packs, burn out ESCs and/or destroy motors. If you want a low headseed to slow things down, then use a smaller pinion and stay above 85% throttle - don't use 50% throttle. 50% collective (with say 90% throttle and 5-6 degrees pitch, ~2400RPMr) for hover is okay for a beginner. Perhaps that what you meant? You need to match the power system components and use the pinion to get in the right headspeed range, then run at 85-100% throttle. Don't fly with the throttle, fly with pitch. You want headspeed to be constant for best performance. Stay above 2400 RPM as too low a headspeed won't give the tail enough authority to hold heading. Also, changing headspeeds makes more work for the gyro and tail servo. I'm also a believer in learning to fly using radio settings that match your target flying style as it saves you from re-learning later. If you aspire to be a 3D pilot, then learn on 3D curves. If you will always be a scale pilot, then learn with hover at 50% collective. Beginner pilots typically start off chopping the throttle to bring the heli down - bad habit; better to learn to switch to idle up before taking off. It's much harder to unlearn bad habits. |
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