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September-2019
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Post  --Oz-- on Wed Sep 11, 2019 8:49 pm

ian1954 wrote:So from the electricity I pay for - i only see 80% of 80% or 64% power conversion. 41.5 watts arrives at my power sockets , 33.2 watts goes into the battery which then provides 26,56 watts to the propeller. 26.56% efficiency.

FYI, decent chargers are now +90% EFF, not 80%.

So overall outcome = 26% EFF in your electric example (I do have a issue with this low figure, but lets go with it), vs 5% EFF of the cox fuel already processed and delivered to your door. Factor in at very best 90% processing/delivery for nitro fuel. So a Cox motor is maybe 4% EFF. That makes the Cox motor to be ~5 times less EFF than electric, plus the huge environmental impact for using it. There is a reason 2 stroke motors are banned for most applications and are not used anymore for the masses.

EDIT: My server power supplies are up to 96% EFF, lets round that down to 90%.
My iCharger 306B is over 90% EFF (synchronous buck/boost converter).

So 90% of 90% is 81% (quite a bit higher than 64%)


Last edited by --Oz-- on Thu Sep 12, 2019 3:04 pm; edited 2 times in total (Reason for editing : Deleted irrelevant data)
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Post  --Oz-- on Wed Sep 11, 2019 9:15 pm

ticomareado wrote:How many gallons of nitro per mile?
At just off idle, just guessing 2oz per mile, so 1/64gal per mile'ish.

Do you realize the preformance of a world championship 1/8th scale nitro car in 1996, 7lbs, 130mph, cornering monster and straight line missile?
I never liked rc fuel cars, the throttle response is a horrible delay vs electric, in 12th and 10th scale, electric drives circles around the nitro cars on the same track.
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Post  --Oz-- on Wed Sep 11, 2019 9:22 pm

ticomareado wrote:What happens to shagged out LiPo batteries in the environment?

Quote "Lithium batteries are generally considered not an environmental hazard except when containing toxic (heavy) metals and disposed of in large quantities".

What happens to unburned nitro and methanol and spewed oil to the environment, your answer can't be good? (again "poor life")
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Post  balogh on Wed Sep 11, 2019 11:43 pm

I thought this was a forum of COX engine lovers  Very Happy ..we eat pork and beef with cholesterol in it and wash it down with beer and wine no matter the unhealthy alcohol and sugar in it...carpe diem.

The environmental impact of these small critters is way less than the plastic or even recycled paper bags we carry our food home in from the supermarkets no matter how healthy vegetables you carry home in them, let alone the emissions from gasoline burnt in large ICE powered cars we drive  then park in the doorway of our sometimes still insufficiently heat insulated single-pane-windowed houses after arriving home from the supermarket or wherever, and we do not seem to constantly blame ourselves about it..at least I do not feel guilty every moment because I live ( BTW in a well insulated house and driving a car that I just measured yesterday on a 700km trip  consumes 6 l diesel (oh what a poisonous fuel!!!) each 100 km at a speed of 150km/h) a civilized life and necessarily leave a tiny stain on Earth here and there like every one of us does even Greenpeace members ...I live reasonably environment consciously, but will not put bitumen on my  skin then spin myself in feathers just because of the COX hobby I have..c'mon...

(I offer an excuse, though..I hate air-conditioning, and the environmental benefit of energy thus saved offsets multiple times the damage I cause with my COX engines... lol! )
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Post  Oldenginerod on Thu Sep 12, 2019 6:07 am

Just guessing, but I suspect that total emissions from every model nitro/Diesel engine used in the world ever would be less than one A380 flight from London to New York, and how many tons of kerosene are burnt in airliners around the world every day?

Methanol is manufactured (not mined like Lithium) as is Nitromethane.  Castor oil is organic!! so that's gotta help the earth, right?

Maybe we should all go back to rubber powered models. Rubber and balsa are natural/organic.
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Post  ticomareado on Thu Sep 12, 2019 6:27 am

Maybe we should just douse ourselves in certified organic fair trade hot beeswax, roll in some free range, no hormones chicken feathers and jump off of a cliff.
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Post  fredvon4 on Thu Sep 12, 2019 11:16 am

Harump.....silly AirBus 370...

use this app...find your area, see the traffic....zoom out

upper left has totals of aircraft in flight

https://www.flightradar24.com/30.48,-96.56/7
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Post  --Oz-- on Thu Sep 12, 2019 11:20 am

All good points! I like the feather idea! Thinking group flight, lol.

When electric efficiency was questioned, I challenged, and not much of a reply. So is electric still about 5 times more efficient than a 2 stroke cox motor?
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Post  1/2A Nut on Thu Sep 12, 2019 12:12 pm

Being a Cox engine site for those who love using them to fly and surface run them don't care how efficient
they are compared to electric motors. Folks enjoy running them regardless of power losses / fuel waste.

Fireworks  Small Cox Logo Horsing Around
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Post  ian1954 on Thu Sep 12, 2019 5:35 pm

I would agree that the electrickery route is more efficient but, nevertheless, for quite a few aeromodellers it can be a tad impractical and often requires substantial upfront investment.

A simple example is the 225 minute run by the little Cox engine on a US quart of fuel. Now, I buy Imperial gallons of glow fuel for £20 and that, if my maths is correct, is £4.16p. (Please fell free to substitute $ for £).for a US quart

Now the typical (i have several variations) 1/2A (US 1/2A) set up that i use employs a 3S 1300mah battery Sport 25C battery. This costs £16,98p and from fully charged to 20% will run for 7.7 minutes,

Why 1300mah battery? Any bigger would be too heavy, any smaller woukldn't run for long enough and too small a battery will fry as it can't deliver enough current,

So, for 225 minutes flying in a day you would need 30 batteries for the princely sum of £509.40. A battery recharge at 1 amp would also probable take an hour. Even for the RC guys, typical flight times are under 10 minutes, which is why quite a few still prefer fuel.

Now most control liners aim for a 6 minute or so flight and that means a battery per flight. While three hours 45 minutes is a lot of flying, an
hour of practise flights or 10 batteries isn't.(£169.80). I battery is 1 US gallon of fuel.

Different setups need different batteries, the larger the model - the more power - either volts or amps. A ringmaster with a 25 setup and 9x6 prop will need a 3300 3S battery (£34).

My 1/2A KK Radian because of the restriction on space for the battery uses 900mah 2S batteries bu because the battery needs to deliver 25amps, it is quite expensive and only gives me a two minute flights time.

Now the batteries can be recharged many times and even recharging the 30 batteries would only cost 6p (excluding charger!) .

As mentioned, a range of sizes of models requires different batteries wheres a bottle of fuel will feed many different engines.

Now for the bad - in a perfect world the batteries should last a very but prang the plane and the battery will be damaged and unsafe to reuse. Likewise, if you use a cheap controller and stall the propeller (tip over on take off) - something will fry. Set the timer wrong and flatten the battery completely ............ put a battery that needs charging in the plane and set it to run for 6 minutes that it hasn't got. Electrickery gets expensive,

There is nothing like the sound and smell of the good old combustion engine!









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Post  --Oz-- on Thu Sep 12, 2019 11:17 pm

@ ian, Some good points and some not so good.  Very Happy

You brought up the electric EFF, and I am totally good with a discussion about it, if others are not, please move on, this is a pleaseful discussion, there is plenty more threads for commenting if this is not your cup of tea. I did not start this thread for elec vs 2 stroke comparison. Your electric EFF link was an eyeopener, thanks for that, I shared with many of my EE friends already!

I bought 12 batteries (4s-1300, in late 2016) for a cost of $11 each shipped on sale ($132 total). I have 1800+ cycles on all of them, and a few are now over 2100 cycles. In 2017 I did 10,400 flights on them, thats 250 hours air-time (flying) and to be clear, they were 90 seconds flights, why, because my old quad has only 9:1 thrust to weight at 430g AUW (the new stuff is up to 15:1), it pulls a peak of 120A and 1800W (input power). 90 seconds of extreme preformance/maneuvers is fine for me (I am not a floater or lapper). I could fly 2 minutes taking the battery down to ~20% (or boring hover for 5 minutes), but I leave ~40% charge left in the battery because it tremendously increases life cycles. The 250 hours of flight was only in one year, I did ~70% of that in 2018 and 30% of that in early 2019, so at least 500 hours of flight on them 12 batteries all for $132. I have retired them batteries from "quad" use, now I use them in my planes, yep, they still going fine only pushing one motor, a single motor has no problem on older batteries for 3d planes.

Using the 3.7 hours on 32oz of fuel (endurance test) would be ~15 hours on a gallon (much worse with TD/etc motor).

500 hours with a 049 is roughly 33 gallons of fuel.
My local hobby shop (robshobbies in hunting beach, ca) charges $40 a gal for 20% nitro and $47 a gal for 30% (out the door, including tax).
That would be $43(a gal @25% nitro) x 33 = ~$1400, or 10x the price of the batteries (not including charging cost). Very Happy

Currently, I use $10~13 motors, about 10~30 times less than what a new 049 cost new these days.
http://www.myrcmart.com/rcx-nk2207-2400kv-fpv-racing-motor-japan-ezo-bearing-n52sh-arc-magnet-p-11838.html

A single recharge of my 4s-1300 pack from ~40% charge is 700~800mAH battery accepted, so 800mAH x 14.8v is 12WH.
With my power supply +90% EFF and charger +90% = 81% EFF
So I pay ~26 cents a KW (delivered, much less with solar, but that's another subject), it takes 14.8WH to charge my battery (81% EFF and 12WH into battery).
So roughly 20,800 pack charges (500 hours of flight) would cost 20,800 x 14.8w = 308KW, at 26cents a KW = $80 in charging costs (including P/S and charger EFF)

Summery:
Electric,,,
$132 for 12 batteries (that are still going)
$80 charging cost for 500 hours of very high preformance flight
Total of $212, both batteries and motors are still going

Nitro,,,,
500 hours with a 049 is roughly 33 gallons (if it lasts that long) and ~$1400 in fuel

Or ~7 times more cost (my batteries are still going, where nitro fuel is done) and 5+ times less EFF

Of course your nitro or electricity may vary from where I live.
Zero maintenance on my BLDC motors, killer top of the line EZO bearings.

Crashes cost money, lol, with my ~$13 motors that takes a massive beating (80mph in to asphalt dirt w/o damage and with only breaking a 37cent prop (or 4 of them, or $1.50 for a bad crash, lol). 049 do seem to take a beating too, with my combat experience with over overwatered soft park grass, the 049 is not nearly as reliable in a beating, but to many factors to really quantify anything, lets call that a wash, but glow plus, how many $5 a pop glow plugs do you go though in 500 hours of flight? My quad motors have well over 400 crashes without and any damage to them ($52 for a set of 4 of them), that's pretty awesome imo.

There is nothing like the smell of 2 stroke burning in the morning, I totally agree, but where I fly, they are starting to complain about electric noise, so 2 strokes ain't happening. I do enjoy the sunny southern california weather (highs in the high 80's, lows in the high 40s, fly all year around)

My battery hangs off the bottom of my quad, and rarely does it get destroyed, I don't use "crappy" esc, I use low cost 30A ESC (rs30a v2 for $10 or rs80a v2 ro $16) that takes a beating, 5S no problem, shorts into the stator no problem, overheating no problem, it hase temp control, even a lost model beacon that has saved my azz many times. BLHeli_S kicks azz in ESC preformance, smooth, low noise (high PWM freq), low stable rpm, very fast response (yep, plane guys laughing, their fing is slow like molasses, many adjustable features with Tx or $2 arduino nano controller.

Thanks for the friendly discussion. Very Happy Happy flying
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