RCCA - How far have we come?

[HauntedMyst]

When it comes to kits, we've seen a tremendous improvement. Batteries have double in the past 5 to 10 years. But what about eletric motors? Is todays stock motor really that much better then 10 years ago performance wise? Are today mods that much better? How does today T1 Reedy compare to their best offering in 1991? Would a 16 turn today compare to say a 13 turn of yester year?

And what about engines? I know the entry level engines are much better in terms of reliability but what about performance numbers?

[bullfrog]

Yea i think that we have come a long way. I mean we have so much more tecnology then we did back in the " stone age" when RC was just started ( and YES im calling anybody over 30 years old an old fart.... that includes my mom and dad so dont flip) But now days we know allot more than we did than say...... 10 years ago. We have all of this adjustable timing, epoxy ballanced, magnet zapped, hand wound , machine wound crap. I think we have come a great distance. Just look at computers ( i know its a little off topic but work with me here) We now have computers the size of a briefcase that STILL has more features than a computer the size of a room didnt have 20 years ago. Fuels have all of this overheating protector stuff in it that TELLS us weather out engine is too lean or not ( you dont believe me? pick up a jug of blue thunder, lean your engine so its WAY too lean, and it will do EXACTLY what it says it will do on the label it will bog down on hard accelerating which tells you its too lean.) just my thoughts

[HauntedMyst]

But that doesn't answer my questions even remotely. We had "adjustable timing, epoxy ballanced, hand wound , machine wound crap" back then. It doesn't say anything about the changes in motors or engines at all.

[BuckNaked]

By there nature... electric motors are very inefficient. This is the reason why we dont see electric automobiles buzzing around the street. Motor technology has not improved enough to even discuss. So to answer the question you could beat me with your ten year old motor just because your a little bit better a driving then me. Motor technology will not improve untill it is reinvented.
Bananas have changed more in the last ten years :)

[HauntedMyst]

Actually, banana's have not changed either fundamentally over the past ten years. What has changed is our farming technics and ability to genetically enhance their reproductive cycles, which have tripled, even quadrupled crop yeilds per acre.

[ILv2Xlr8]

I disagree with bucknaked.
Battery technology has not kept up with motor technology, but the most advanced motor technology has not trickeled down yet to our RC hobby.

Bucknaked, electric motors are EXTREMELY efficient, and that is precisely the reason they are showing up in hybrid electric cars today, the only reason we do not see total elecric vehicles is because the battery technology has not kept up with motor technology. A lead acid gell cell for an full size electric vehicle cost $200, where as a Nickel Metal for an electric vehicle cost $2500, and fuel cells are not even close to production. Full size electric vehicles mostly use 3-Phase AC Induction motors, NOT DC. They are brushless, and generally flux-vector controlled. AC is much more efficient than DC (which is why it comes to your house that way) and as far as AC motors go, an AC motor allows 20-100 times the power density than that of a comparably sized DC motor.

The next large step for our hobby could be multi phase AC motors! To illustrate this dream, while your Green Machine 3 outputs 120 Watts, a similar sized advanced AC motor could output 250 watts to over a Kilowatt provided the batteries could feed that much power. The windings would be the can, and instead of an armature you could have a permanent magnet rotor. In place of a speed controller, you would have an inverter that is driven by a DSP or microcontroller. When will be the first application of a high output AC motor in our hobby? How about an insane speed run in a pan car using 20 cells that can output the high current draw nescessary for a high output AC electric motor?

enuff dreaming for now...

just my $0.02

[BuckNaked]

I'll stand uncorrected! Electric motors are VERY inefficient. Efficiency of a electric motor is rated by energy in vs power out. Physics 101. Read up on it and do the math. Why...is the big question. One reason is that a good amount of energy is wasted in the form of heat. If there was a electic motor with close to perfect efficiency we would have 30 minute heats. The reason why we see hybrid cars is because gasoline engines are very efficient in contrast to electric motors. Hybrid cars use a gas engine to help the inefficiecy of the electric.

[chosen1]

I know this is off topic but ILv2XLr8's post drove me up the wall. I am an electrician and the reason that we use AC power in our houses is in no way because AC motors are more efficent than DC. We use AC in our houses because it can be transformed (stepped up or down in voltage) this makes it more efficent to distribute. I would explain this here but it would take up too much room and this is not a "AC vs DC power distribution forum."



p.s. it is true that the reason you don't see electric cars much is the batteries are expensive and heavy.

[RichieRich]

I disagree with bucknaked too. Electric motors are very efficient compared to gasoline engines. In fact, internal combustion engines only turn about 1/3 of the energy in the fuel into usable power. That doesn't seem terribly efficient to me. What physics 101 class did you take?

[BuckNaked]

Not to stay off topic. But I must correct people when they are wrong. A/C is not more efficient then D/C in general! High voltage is more efficent then low voltage. The higher the voltage the lower the current for the same amount of power. This is one reason why we see A/C in homes. One more is because D/C is very dangerous at high voltages. Power company's pefer to transfer power in High Voltage D/C repeat D/C when moving power over large distances. ..And even though are friend the electrian said we use a/c in houses is because it's easy to step would be a typical electrian answer. Most electrians are cable pullers and and can bearly tie there on shoes. The most important reason why we use a/c in homes is thats the way it's created. Power generators work like a electric motor backwards. You spin it and get output this output is a/c since it is spinning. A good example is a atenantor in a car.. the gas motor spins it. it puts out a/c voltage which goes through a recitfier and bam.. you get d/c voltage about 16-18Volts at idle which charges you 12V battery.
And why do people keep saying electric motors are efficient. Do the math and prove me wrong please!

[Crazy Canuck]

The reason we use AC in homes is that there is less resistance in the flow, so it is easier to transport long distances.

[chosen1]

Can barely tie my shoes??????????? Cable puller??????????????????
Was that really necessary??? how many electricians do you know????? I personally studied in an electrical program for 3 years.

first high voltage is only more efficent when it is being distributed. high voltage/low current and low voltage/high current efficencies are almost identical in end user devices.
Again the one reason we see A/C in our homes is the ability to be transformed.
D/C is no more dangerous than A/C at high voltage (do you understand ANY basic electrical theory??)
Power companies DO NOT I repeat DO NOT use D/C to distribute power. Like I said before D/C cannot be transformed if you have 120 volts D/C then it stays 120 volts D/C without the use of expensive and power-robbing inverters. with A/C power it can be stepped up to distribution voltages with a simple transformer- that is what that grey cylinder on the pole outside your house is it steps the voltage down from 13,200 volts to the 120/240 you use in your house
I stand UNCORRECTED

btw what is your problem w/ electricians? did one beat you up once??
;)

[BuckNaked]

I'm Pulling on your chain chosen1 trying to get more infomation from you. I've seemed to got your attention :).
You are somewhat right. MOST SHORT distance transmittal lines are A/C. And I never argued about the abilty to step voltage. But the reasons behind all this is because or the orgin.
Now answer this. 240v a/c is measured in rms. it's peak voltage I guess would be around 300v in most areas. So if you had to choose 300v a/c at say 120 cycles per second or 300v d/c (d/c is not measured in rms) to be shocked by what do you chose and why?
:confused:

[Cosmo]

Well, those of you who have been around this hobby as long as me try this:

Go back through all your old stuff and find some of those old Parma or Reedy stock motors. Compare them to what you have now.

Or, better yet, look at some of your old modifieds. I have an old Trinity modified 14 turn motor(I think it's called a "Dirtinator"). Just out of curiosity I cut the comm, changed the brushes and springs, and dynoed it the other day. It had slightly higher RPM's, but it had less power, torque, and efficiency than the Fantom Green Machine I'm running now.

[BuckNaked]

Perfect Feedback cosmo, I curious how much less was it. I have a old reedy D's mod. 14 turn. It will hang with a new one but is less efficient, running hotter!

[TUCRACEMAN]

Where's the ignore button when you need one?

[chosen1]

You are right A/C voltage is measured is r.m.s. the peak is r.m.s. x 1.414 in your example would be ~339 (in whatever area you are in), now, the flaw in your arguement is the peak measurement in a/c voltage is a useless measurement the reason we use the r.m.s. measurement is that is the amount of a/c voltage that will do the same work as the same voltage in d/c (240 r.m.s. volts a/c is capable of the same work as 240 volts d/c)
so to answer your question, it would depend on the amperage. I would rather get shocked by 10,000 volts (a/c or d/c) at .1 milliamp than 120 volts (a/c or d/c) at 50 amps.

p.s. show me some proof of power company D/C distribution lines and I will send you a nice crisp one hundred dollar bill;)



Tom

[ILv2Xlr8]

Sheeesh, I did not mean to start an argument, and a lot words were put into my typing.
Let me clarify myself, as RichieRich stated, an electric motor is more efficient than ANY fuel powered motor, and by a factor that I consider EXTREMELY more efficient when electric motors can achieve efficiencies greater than 95% when a gasoline one is one third of that. When you can disprove this simple fact bucknaked, you will have exceeded and baffled the knowledge of all the mathematicians, engineers and physicists on this planet. In no way did I say as chosen1 misquoted me that for the same reason AC motors are more efficient than DC that it comes to your house that way;
I only made a general statement that AC is more efficient than DC and included the example of power distribution but was emphasizing the reason for motors: Increased power density with multiphase windings. The proof in terms of math that bucknaked demands but must have missed during his Physics 101 class is done by performing a gaussian triple integral over the magnetic fields produced by a 3-Phase AC winding, and a simple DC winding.

As far as bucknaked’s analogy for a motor saying “you spin it and get output this output is a/c since it is spinning” let me just add, hook the shaft of your RC motor to a drill, spin it and hook a voltmeter up to the leads on your motor and let us know what you get.

I did not want to start any arguments or provide for any bashing, so back to the topic at hand please.

My opinion to the origional question started by HauntedMyst was that batteries have not excelled as fast as electric motor technology.

:D

[ttweedle]

Uhhhhh, what is electricity??????:confused: Is that what comes out of my batteries?:confused:


This is about how I feel after reading this post, that is soooo way over my head.

Travis

[outsider]

We've come a long way but we have a long way to go. We're not even up to LithiumIon in batteries never mind the more advanced stuff like Lithium polymers and methenol fuel cells. Anyone know the Amp pull of brushless motors compared to brushed? Could you get by with the lower amp LiIon and LiPolymers?

[Interceptor]

Just my 2 cents, but the reason why battery technology for real cars hasn't improved is because the oil companies are holding it back. If all the oil dried up today, next week they would release electric cars that have the power and range of our gas powered cars. They also hold the patents on several super efficent engines that they bought from the people who designed them.

[TUCRACEMAN]

Thanks Jeep. That is great to know with a BunkNaked running around.
~Dave

[BuckNaked]

Originally posted by chosen1

p.s. show me some proof of power company D/C distribution lines and I will send you a nice crisp one hundred dollar bill;)

Tom [/B]

Just trying to end a arguement with Tom the Electrician that cant tie his own shoes. Anyone who is a little interested in electronics may enjoy this. Why d/c is more efficient then a/c.

p.s Tom (hvdc) high voltage direct current. Learn it. Know it. Live it.

http://es.epa.gov/new/business/sba/options3.html

Does anyone think he will pay up. Electrians make good money. But maybe he's not one?

Buck.:eek: :eek: :eek:

[RC10T3]

yea but that article was in the future tense.

[BuckNaked]

Sort of, Kind of. But it is also 7 years old. Back then they had many hvdc lines in place. Today there's 100's.

[chosen1]

that article is entirely theoretical. it doesn't prove anything. I could write an article about how cold fusion would solve all of our problems, but just because i wrote it doesn't mean it is in use. so don't expect anything in the mail with that for proof