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HomeAircraftHelicopterHelicopter Main Discussion › v-curve vs flat... efficiency...?
06-06-2009 06:12 PM  9 years agoPost 1
flipteg

rrNovice

Lilburn GA

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in a non governed electric, a lot of the people in the forums say that flat throttle curve is the most efficient way to go... i do not know yet if it is true but for the same type of flying (figure 8's) it seems to me that v-curve is more efficient in terms of mAh charged back to the battery... meaning that with a throttle curve at 100-92.5-85-92.5-100 i am seeing around 30 seconds more flight for the same mAh charged pack as a flat curve at 90-90-90-90-90... theoretically, they should be about the same since i spend most of the time at around 3/4 stick for simple circuits and figure 8's... also on quick collective pumps, there is a slight audible head bog witht eh flat 90 where as with the v-curve there is none... battery is a TP Pro 30C 2250mAh...

i don't know a lot about the subject and i'm not trying to dispute what other people think... i'm still just trying to figure out which one to use... please advice...

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06-06-2009 06:20 PM  9 years agoPost 2
BarracudaHockey

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Jacksonville FL

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Efficent as in the speed controller runs cooler when its not switching on and off.

Andy
AMA 77227
http://www.jaxrc.com

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06-06-2009 06:30 PM  9 years agoPost 3
AirWolfRC

rrProfessor

42½ N, 83½ W

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I suspect efficiency is the same either way. The ESC is switching on and off as necessary to hold the head speed where desired be it on command from the TX or a constant speed mode set in the ESC.

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06-06-2009 07:07 PM  9 years agoPost 4
flipteg

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Lilburn GA

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i just got back from flying 3 batteries... throttle curves are as follows...

battery 1 - 85 flat...
battery 2 - 90-85-80-85-90...
battery 3 - 88-85-82-85-88...

all batteries are the same TP Pro 30C...

i flew the batteries as i did before... circuits and figure 8's and i flew them as similar as possible... i don't know yet which is the most efficient in terms of current usage as i haven't charged the batteries yet, but it is very obvious that battery 2 had the most feeling of "pop"... that pop feeling was so great going from the 85 flat that battery 2 ALMOST feels like it's ballooning... but as the 5 minute flight wore on, that ballooning feeling just became a feeling of increased sensitivity on the collective... battery 3 felt very close to an 85 flat curve... but after only a 5 minute flight with 90-85-80-85-90, i found that the heli was dipping more than i'd like with battery 3... i attribute this to going back to back with two very different collective sensitivity...

so, although they SHOULD be the same like most will say, there definitely is a differece between flat and v-curve...

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06-06-2009 07:07 PM  9 years agoPost 5
LaurenceGough

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UK

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I run flat 100% because it's much, much better for the tail and bogs less. It's brushless motors which are more efficient at the higher throttle settings more so than the ESC.

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06-06-2009 08:02 PM  9 years agoPost 6
outhouse

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auburn ca

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yep run all my helis 100 flat.

V curves are better for gas rigs most electrics run 100 flat

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06-06-2009 08:43 PM  9 years agoPost 7
flipteg

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Lilburn GA

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hi, thanks for the comments but i'm not really asking what percentage of throttle is best... i know most people say that the way ESC's work is that with a flat curve, when the load is increased, the ESC will just draw more current to maintain the head speed, and maybe that's really how it should be on paper, but as i said earlier, in actual flying, 85% flat had a definite change in head speed when pitch was increased...

because if ESC work as claimed, then i should not get any head bogging even if i'm only running at 85% flat...

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06-06-2009 08:44 PM  9 years agoPost 8
CT.Chopper

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Meriden, CT

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100% flat-out here too

Rob Landry.

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06-06-2009 08:48 PM  9 years agoPost 9
AirWolfRC

rrProfessor

42½ N, 83½ W

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A pitch curve attempts to predict the needed command input for maintaining a constant head speed.

Running 100% all the way lets the ESC maintain the head speed (when set for that mode) without any prediction (guessing) on the part of the TX.

Efficiency isn't really a part of the performance question.

Although you may get a slight efficiency improvement if your ESC allows a setting for how "tightly" it controls the head speed. Loosen it up a bit and the efficiency may improve slightly.

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06-06-2009 09:26 PM  9 years agoPost 10
outhouse

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auburn ca

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your missing the point here at %85 you will get bogging no matter what because you dont have enough headspeed to begin with.

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06-06-2009 09:38 PM  9 years agoPost 11
LaurenceGough

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UK

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I tried a flat 95% curve and I didn't like it one bit, felt way too slow at the ends.

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06-06-2009 09:44 PM  9 years agoPost 12
Micro-Maniac

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Pasco,Washington Formerly: Captain Chaos

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You may get better battery efficiency from a V-curve simply because you are flying at a lower throttle part of the time - You will get better performance efficiency from a flat 100% curve because this puts the motor closest to it's peak efficiency rpm along with providing more enertia and less blade deflection etc for a particular control rate = less rpm loss vs a lower throttle or V-curve - You're just trading performance for flight time

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06-06-2009 09:47 PM  9 years agoPost 13
Gyronut

rrProfessor

Martinsville In.

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If you are going to continue to run lower headspds then your going to have some bogging down, thats just the way it is.

Even when you are running gov's there is going to be some HS loss.

Rick

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06-06-2009 09:52 PM  9 years agoPost 14
AirWolfRC

rrProfessor

42½ N, 83½ W

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You will get better performance efficiency from a flat 100% curve because this puts the motor closest to it's peak efficiency rpm along with
? ? ? The peak efficiency rpm is a hard number unique to the motor in use, not dependent on how it's operated.

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06-06-2009 09:56 PM  9 years agoPost 15
Micro-Maniac

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Pasco,Washington Formerly: Captain Chaos

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You should be matching a motor a voltage and a gear ratio that loads the motor nearest it's peak efficiency at 100% throttle - So I'm assuming the heli is setup close to correctly in this manner

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06-06-2009 10:05 PM  9 years agoPost 16
AirWolfRC

rrProfessor

42½ N, 83½ W

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Problem is that motors typically don't tell you what the best efficiency rpm is.

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06-06-2009 10:10 PM  9 years agoPost 17
Micro-Maniac

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Pasco,Washington Formerly: Captain Chaos

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I think good motors generally spec an efficiency rating but it's not an exact science to the average electric heli hobbiests - If you load the motor to near 80%-90% of it's freerun rpm you're certainly close enough in the ballpark for about any BL motor - Most heli kits come with a motor that I only assume is decently matched to the heli it's packaged with

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06-06-2009 10:19 PM  9 years agoPost 18
AirWolfRC

rrProfessor

42½ N, 83½ W

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Can you identify any motor that spells out the efficiency and the rpm of that efficiency ?

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06-06-2009 10:28 PM  9 years agoPost 19
Micro-Maniac

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Pasco,Washington Formerly: Captain Chaos

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I think it's usually on the manufacturer's websites - Look some up - I think Axi motors spec their efficiencies

Someone else might be better qualified to answer your specific questions about this as I usually just fly whatever motors come with the kits and replace them with whatever is popular when they break

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06-07-2009 02:13 AM  9 years agoPost 20
outhouse

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auburn ca

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boy this thread is going downhill fast.

you guys must like to argue over nothing.

for one the heli will fly like junk at low headspeeds so efficiency doesnt matter much and the juice you will save form %80 to %100 is only going to be a few seconds.

this thread is like,,, if I had a race car and I put cheap tires on it with regular gas how much further can I drive

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HomeAircraftHelicopterHelicopter Main Discussion › v-curve vs flat... efficiency...?
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