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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › tim jones prototype ys120 trex 700 video is up for viewing
01-13-2011 09:23 AM  7 years agoPost 61
Heliguychris

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Perth, West Australia

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Hell yeah for cubes

Licensed (CASA) UAV operator certificate holder 1-YFOF5-01 www.helicamaerial.com.au

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01-13-2011 12:36 PM  7 years agoPost 62
BladeStrikes

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Shelby TWP,Mi

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^^^^ ..

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01-13-2011 05:48 PM  7 years agoPost 63
SamurAchzar

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Israel

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Read, then re-read what ShuRugal wrote, and understand my gripe about E power comparisons.

The fact the motor is loaded far beyond its efficiency and pulls huge amount of watts doesn't mean squat about how much power it's really making. The efficiency of an electric motor is great until it hits a brick wall somewhere towards the end of its consumption spectrum.
The peak watts drawn by a motor are just that, they don't indicate how much power it's making. After all, the reason that it's peak and not sustained is because the efficiency falls down so drastically it just overheats instead of making power.

This is when discussing MFG rated peaks, of 10 seconds to a minute; I'm not talking about the ridiculous spiking you see in data loggers. That's not different than a short circuit basically, no way you see this wattage passed on to the rotor.
You don't see many setups pulling 160A+ through SUSTAINED maneuvers (what takes to produce 7.4kw, or 10bhp, on 12s), and even then the efficiency of the motor is in doubt.

Also, there's some power lost through the wires and ESC internal resistance, and it only goes up with the current passing through. That's likely not to be shown in the loggers (which, I assume, measure the battery side, not the phase side).

That said, if you have an electric motor and an IC engine both rated to the same horsepower on a dyno, the E motor will feel stronger because of it's flat-ish torque curve, while the IC engine could fall out of the powerband under specific maneuvers.

That being said, for the moment I'm more than content with the power of my 700N, to the point of tuning the engine on the rich side for longevity - I really don't need everything it can give.

I'm guessing that a 700E compared to a 700N will give 50% more power, maybe, certainly not the multiples it might have on paper.

Finally, looking at how simple our nitro motors are compared to full sized gasoline motors, you can bet there's still alot to be done. Injection, supercharging, ignitions, it's just a matter of the nitro manufacturers responding. 3.4HP for .91 engine (roughly 15cc) is far from impressive, it's being done in passenger cars on less energetic fuel with many more constraints than we have.

It's basically up to YS/OS to fight back against the E trend. Overall, the future of the R/C hobbies is - unfortunately - all electric, but the way there will be interesting.

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01-13-2011 05:57 PM  7 years agoPost 64
ch-47c

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san jose, ca

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Hummm.

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01-13-2011 05:59 PM  7 years agoPost 65
red_z06

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Dumont, NJ

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Samur,

I see your frustration.
See below.

https://rc.runryder.com/t615893p1/

www.JustinJee.com

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01-13-2011 06:05 PM  7 years agoPost 66
SamurAchzar

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Israel

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Samur,

I see your frustration.
See below.

https://rc.runryder.com/t615893p1/
Word.

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01-13-2011 06:28 PM  7 years agoPost 67
Justin Stuart (RIP)

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Plano, Texas

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^^^^ Well said.

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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01-13-2011 08:19 PM  7 years agoPost 68
ch-47c

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san jose, ca

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Can't argue with that.

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01-13-2011 08:42 PM  7 years agoPost 69
Heliguychris

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Perth, West Australia

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Samur and RED, i read your authoritve posts, and ill ask you guys, how then to measure accurately the power from our E motors ? You guys make some most exellent points about peaks, losses and efficiencies, that are entirely sensible. Is it as simple as an Eagle tree, and find ya best 5 odd seconds under the graph ?

As stated before, there is no manouver.....perhaps with the exception of continous fast flips, that you can draw max power for 30 secs.....unless its UAV lol

Cheers guys.

Licensed (CASA) UAV operator certificate holder 1-YFOF5-01 www.helicamaerial.com.au

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01-13-2011 08:43 PM  7 years agoPost 70
SamurAchzar

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Israel

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Here's a wonderful example of this subject:

The guy marked the peak consumption. These are spikes that to me look like 2x the useful range of the motor. Looking at that graph, my estimation is that this motor is not really useful for more than 3kW of actual sustained power. Look at the way the RPM drops in nice correlation with these peaks, while it holds RPM nicely on the "wide" parts of the power graph.

My guess is that these are sudden pitch changes which cause the motor to spike; look at slightly before the 100s mark, there's a "fat" area of 10-15 seconds - probably FFF of some sort - where you see the amps gradually rising and the RPMs gradually dropping. I'd say the motor hit it's efficiency wall right there.

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01-13-2011 08:48 PM  7 years agoPost 71
SamurAchzar

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Israel

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Either run the motor on a dyno (shouldn't be very hard really; you can build a nice dyno using another brushed DC motor that you couple to your motor), or more realistically, climb from still for 4-5 seconds and see the point the RPM begins decaying, that would mean you've hit the motor max power. Yes you might see more consumption after that, and yes you'll probably see a grand ol' spike if you pump the collective hard enough from still position, but they'd be meaningless.

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01-13-2011 09:11 PM  7 years agoPost 72
Heliguychris

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Perth, West Australia

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i see i see i see

FFF will give a good idea..... ill give that a go,.....i got a couple of tricks to fudge that tho

Thank you very much for the info

BOT..... now wheres some vids of this motor

Licensed (CASA) UAV operator certificate holder 1-YFOF5-01 www.helicamaerial.com.au

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01-14-2011 01:51 AM  7 years agoPost 73
heli papa

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shannon,NC

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Thanks Guys for all the helpful info on understanding how to calculate the E power from both sides of the fence

Seeing the graphs and tutorial on them(with having data logger myself)helps me to understand that electrics may put out 10-12 HP but only in burst or unloaded.that answers my thoughts of continuous power which was mind boggling to me

Even tho im still leaning toward NITRO for now as im still learning these electrics which i own(It seems i still have alot to learn)But in my experience so far nitro is easier,less time consuming and really more affordable.

Saying that i know in time that E power,Batteries,chargers,esc and power supplies will advance even further becoming more user friendly and cheaper to the hobbiest

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01-14-2011 02:05 AM  7 years agoPost 74
red_z06

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Dumont, NJ

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electrics may put out 10-12 HP but only in burst or unloaded
It is the power you put in in an instant (peak). It says nothing about how much you are getting out.

It is much like shorting out a wall outlet and say I just drew 1000w of power.

www.JustinJee.com

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01-14-2011 02:30 AM  7 years agoPost 75
heli papa

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shannon,NC

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red z06

Im with you all the way,I just found it hard to believe that a E motor in a 90 size heli could put out as much power as my twin cylinder 3w100

I watched the videos and will admit they seem to have more power but not 2+times the power.

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01-14-2011 06:11 AM  7 years agoPost 76
Band1086

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Kennewick, Wa. USA

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It is much like shorting out a wall outlet and say I just drew 1000w of power.
Not sure how you can compare it to shorting when the motor never even really bogs. I've seen 8000W logged on the Ice ESC on one of mine, and that motor never bogged the whole flight. From what I've learn a motor will only draw extreme excessive current when it stalls or gets close to being stalled. Correct me if I'm wrong...
I watched the videos and will admit they seem to have more power but not 2+times the power.
I think you'd be very surprised if you ever had a good E set up.

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01-14-2011 02:08 PM  7 years agoPost 77
ShuRugal

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Killeen, TX

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an electric motor begins to draw extreme current when it is forcibly slowed down below the RPM it wants to be turning for voltage it is receiving. You won't notice a significant decline in head-speed or 'flying-power' when this begins to happen because of 1) the gear reduction, 2) the very high head speeds e-helis tend to be run at in the first place, and 3) the fact that an electric motor has a nearly flat torque curve that slopes downwards from low to high RPM.

What you are "feeling" in power difference when you fly an e-heli is the flat torque curve and the fact that loading the motor up and slowing it down forces it to produce more torque.

If you want to actually talk qualitative differences in power, you need to run the motor on a dyno at a constant load for a minute or two.

To put this into perspective, there is a nice chart giving average appliance consumption rates on this website. an electric oven at 350 degrees draws an average of 2000 watts. the average clothes dryer draws 4000. a 2-ton air conditioner eats about the same. You are claiming that your ~1.5"x3" electric motor puts out anywhere from the same power to twice as much power as an industrial air conditioner or the clothes dryer in your laundry room, that it puts out two to four times the power of your kitchen oven.

That much power output for anything beyond a momentary spike would destroy a motor that small simply because a motor that small cannot use sufficient gauge wire to prevent rapid heat buildup at high current, an does not have enough mass to effectively dissipate that kind of heat.

You want to know what a motor built to hand 10 HP of constant dudty-cycle looks like? Then click away. Let's see someone put that in their 90-size electric.

AMA 700159

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01-14-2011 04:02 PM  7 years agoPost 78
OICU812

rrMaster

Edson, Alberta, Canada

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Ok so back to the original meaning of this post. Any videos yet proof is in the pudding let's see how it performs, it has to be broke in by now??

...Once upon a time there were Nitros, flybars and frequency pins...

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01-14-2011 04:05 PM  7 years agoPost 79
Band1086

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Kennewick, Wa. USA

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That much power output for anything beyond a momentary spike would destroy a motor that small simply because a motor that small cannot use sufficient gauge wire to prevent rapid heat buildup at high current, an does not have enough mass to effectively dissipate that kind of heat.
Agreed, I'm not saying it will hold that kind of power on a continual basis, but the fact that this little 2" X 3" motor can spike to that W/O bogging is impressive to say the least. And from a practical stand point, I.E., flying, there is a real difference between all of the 90E motors and all of the OS and YS glow engines I've ever had. And that difference what we're talking about here. And that difference is awesome. I simply can't say enough about it. It's a steeper learning curve with the big electrics though, learning about all the pros & cons of different motors and ESC's, what batteries are the best for a particular application, battery care, etc,(hence it's not for everyone) but the in flight advantages are well worth it. Then the only disadvantage is flight time, and that's only 2-2.5 mins, with comparable head speed. And I think we will see that difference diminish in the near future. We lost that much going from a .60 to a .90, but we had to have the power!.

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01-14-2011 04:16 PM  7 years agoPost 80
ShuRugal

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Killeen, TX

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And from a practical stand point, I.E., flying, there is a real difference between all of the 90E motors and all of the OS and YS glow engines I've ever had
Yes, I agree with you on that point. I don't own any particularly large birds (400 Cypher and .30 Nexus) but the e-Motor is definitely harder to bog than the .30.

My main beef is when people start waving around the 10μs peak at 5-8 kW their ESC logger recorded as being an actual performance indicator because 1) wattage drawn through esc != wattage put out through the pinion (heat loss in ESC, wires, windings, magnets) and 2) any peak recorded that is above the motor's efficient operating range is turning almost 100% into heat.

Yes, electric motors outperform nitro motors of the same class. No your 700 electric does not have a 10HP motor in it. That's all i'm getting at.

AMA 700159

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