|Jan 09, 2013, 04:44 PM|
Finally got a video uploaded for the P-80! Sorry it's in the RCG Video Gallery though. But its the best I know how to do. 100mph Looks great! As I get a bit older I need colors to help me see, let alone fly my planes. Great Design btw.
|Jan 11, 2013, 04:45 AM|
Both my Xmas models have flown now... both fly very well but lack power, so I need to find out what are the best setups to use...
They are both flying on 1 cell 160mA with a 4500kv 5gm brushless and 5x3 prop..they both weigh around the 40+ gms
I am only getting enough thrust for a good climb rate, but not for any vertical so I am very dissapointed there...
|Jan 11, 2013, 05:45 AM|
Hobbyking alsso have a micro 1s BL setup with a gearbox. If you want to remain BL thats your best bet, although its pricy.
EDIT: I had a closer look at your pics, they look like very nice planes. But more to the point I see that you already have decent batteries, and the way you plugged in the ESC is inefficient. Try connecting the battery directly to the ESC, with only the one signal wire going to the RX
|Jan 11, 2013, 05:53 PM|
|Jan 12, 2013, 04:12 AM|
I have started a micro thread to discuss what power setups we use on what models etc
how do they perform etc
I would be pleased if you will also show your models on there , describing your exact power setup in use..
eventually It will give us all the info needed to avoid getting poor results
Its also worth describing what didnt work, so it can be avoided
Also worth adding are products available .. gearboxes motors ..how do they perform ..are their quoted specs accurate...
Any usefull info
|Jan 12, 2013, 06:27 AM|
I went there and saw all the responses, I will add my stuff too.
It would be good for all if you used one of your first posts as an index to those that state their performance results. You could put:
I know it would be extra work for you, but it might become one of the best references out there.
You might even arrange a Google Spreadsheet where everybody could make entries and have even more columns, such as RPM, Thrust, Amps, Watts, and other things, and it would be open to all, or you could restrict it to a password you give by PM.
|Jan 13, 2013, 09:39 AM|
yes I will certainly keep post 1 updated and linked to the results...please keep that thread for micro motors ans small stuff only though .... say up to 10gm on the motors....
Here is something of interest to you micro fliers.. not a plane , but Ive been playing with LED lights after watching some night vapors flying..
I have already done a night kites thread and put some info on DIY lighting.. so I started playing with the bits already on hand..
I had various colors in 3mm that came with resistors to run them from a 12v(3 cell is fine) but they are all rated at around 3.6V...so the first trial was a direct connection to 1 cell..
they all go well but use near 100mA as they run..
So I then used the resister for the 12V setup and they still work... nowhere as bright but only about 2
mA when running, and certainly visible enough, because normally they are over bright..
Here is a short video showing the B>G>W and then what happens with the flasher, which sits between the blue and the green...every time the red on the flasher comes on , all the others go off...
mind you I might use it like that
to stop geting bored at the video you only need to watch a few seconds at the start, then move to near the end..
Next I tried different colours...running and wired individually... blue was good...white a bit brighter ..green good...yellow dim.. red dim.. flashing red/blue ok..although the red componant was dimmer
The yellow and red wanted about 4mA to run...higher than the others
Next I wired 1 resistor in the circuit and put on all the lights at once...
Results are odd to me but I am sure there are members who will give the explanation..
I found that I could run the white blue and green all together nicely...
Adding either of the Yellow or Red.. the B>G>W would stop working and the other color worked dimly by itself....
Adding the R/B flasher... the B>G>W would all flash, but all 4 worked ok.... testing the 4 were using 3mA only, so will hardly dent your little 1 cells when compared to the motors draw...
|Jan 13, 2013, 10:00 AM|
When using LEDs, you must read the voltage they drop across it. You said "3.6V", but it will differ on each color by about 0.5v among them.
The LED must get that voltage or they don't produce light at all, and they TRY to draw unlimited current, so the resistor is used to limit the current.
So a 3.6V LED in series with a resistor, across 12V causes the resistor to drop 8.4 Volts, no matter what the value of the resistor is. Most 3mm LEDs draw about 10mA, so find the appropriate resistor value by dividing the dropped voltage by the desired current, or:
8.4V / .010A = 840 Ohms. Then select the nearest standard value or 820 Ohms, or Grey-Red-Brown meaning "8"-"2"- and 1 zero.
If you can "fit" a couple of LEDs in a string - volts-wise that is, you can be more economical of your current, you just have to figure a new resistor. So two x 3.6V = 7.2V then our dropping resistor would be 12V - 7.2V = 4.8V And the value would be 4.8V / 0.01 = 480 Ohms, which is near 470 Ohms or Yel-Vio-Brown.
Note that with all these resistors there will be a tolerance color band of Gold or Silver, and there may be another band for temperature tolerance, so this may help you know which end to start with when reading the bands. I have worked with them for years, and I practically just see the numbers (sort of).
Now, pursuing that power saving thing above, you could put 3 in series: 3 x 3.6 = 10.8V, and then your resistor needs to drop just 1.2V. You would use a resistor of 1.2V / .01A = 120 Ohms. With this you get three lit up for the power of one! BUT, when the voltage drops, the LEDS will reduce in intensity, to the point of going out entirely at a supply voltage of 10.8 volts.
You can get fancy and make an active series current regulator, and I will help people through that if they so desire, but it is hardly worth it for these applications. Remember that a 10mA load on a 160mAh battery will run 16 hours, so efficiency is not important...
Almost missed this, if you use a one cell battery, you have about 4.2V to 3.3V, so there will be some LEDs you can't run. You can read the Voltage across various LEDs you have with a 12V supply and an 820 Ohm resistor in series. While it is on, read the volts across the LED itself. Some LEDs will operate with only 2.2V across them, and they would be best for one cell applications.
Whatever LED you select, do this:
1. Put in in a circuit that allows about 10mA to flow
2. Read the voltage across the LED
3. Figure what your preferred supply voltage is, and subtract the voltage in step 2
4. Figure the resistor needed by taking that voltage found in step 3 divided by 0.01
Put that value or near that in series with the LED.
Here are "standard" 5% tolerance values, this is what you will have available for your experiments:
You will use ones from the "Brown" column.
|Jan 13, 2013, 11:55 AM|
different colors draw different ammounts. elecricity takes the path of least resistance, so when i wired white, red and green, only the red lit.
i ended up running resistors to each one. this also lest you 'tune' the light brightness.
white i run at 12 ma, and green as well, or green at 20ma, and usualy run red at 40ma.
the eyes dont like to see red, most of its invisable.
|Jan 13, 2013, 12:53 PM|
Did you wire White-Red-Green in series and feed it through a series resistor, OR
Did you wire White,Red,& Green in parallel, and feed it through a series resistor (...as I suspect).?
If the latter, then the one with the lowest "firing" voltage would light, and keep the voltage too low for the others. Hence the "path of least resistance", as you stated.
The 40mA sounds a little high, I hope it can tolerate that.
|Jan 13, 2013, 03:07 PM|
most leds specs say 30ma, max, but thats at 1000 hours. if i get only 100 hours of life, (10% ife span) im happy ( thats a LOT of stick time )
i wire red, green, white in parallel and put resistors on the pos wire of each led. (just for visual refference)
wiring in series i never tried, cuz the voltage drop for three different leds. as far as the voltage, its not much of an issue. the LED is far more concerned with amps than volts. at any rate, the life rating goes waaay down, but it still very high.
(example: usb stick drives. when was the last time one died on you? they have a limited life, and some manufactures make a big deal of 'last twice as long as the comtitition', but were still talking years of lief out of usb drives. practicaly speaking, most planes (micro) dont get that long of life.)
i once ran ebay white LEDS with no resistors (50mah total) through an AVR procesor as a flasher unit, 0.4 seconds on, 3.5 off, for a week with no failure. in the end i sold it as i figured 7*24 - 168 hours. 5 minute a flight, = 2000 flights.
this was the worst abuse i have ever thrown at the leds, and it did fine.
perhaps the guy i sold it to can chime in???
besides, the brushed motors are the same. datasheets show 1000 hour life, but at 1V. we run them a 400% and get maybe 10- hours and are okay with that.
|Jan 14, 2013, 02:11 AM|
Thanks for the LED/resistor maths... I am going to use the colors that are compatible for the single cell use..the white , blue and green.. that will give me enough variety for the micro models orientation without adding too much weight... it will be close up flying so just the few lights will be plenty, and the fact that they are a bit dimmer than their brightest wont matter...
When I use LED's on my night kites on 3 cell power I wire them in parallel harnesses like nemoskull , often they are often over bright...they can be seen for miles...and I use 20-50 lights on the model, so that can draw up to 1/2A...
I measured the current drawn wired as in the video and the 4 LED's were using between 3 and 4 mA total only so that wont loose me much flight time...
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