Typical Newbie Question???
10-11-2002, 02:36 PM
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Typical Newbie Question???
Heeellllpppp! Though somewhat experienced in fuelie-flight, I'm a "newbie" to electrics, and am finding certain aspects to be more than a bit confusing. In the world of fuel planes, you can buy a .40 size engine from any manufacturer and, though there may be some performance differences, you can expect that engine to function reasonably well in virtually any 40 size aircraft. In the world of electrics, there is no common standard in use by motor manufacturers. Mega-Motors, Aveox, Astroflight, etc., all use different numbering systems, making it very difficult for one to decide if motor ABC from one company can be used in the same place as motor XYZ from another. Not to even mention the question of whether to go can, cobalt, or (VERY expensive) brushless! Astroflight has made a valiant attempt at helping us slimers convert TO THEIR PRODUCT, but not so the other companies. Is there any one source that attempts to tie this all together into some meaningful matrix? Something that perhaps gives a reference to how different company's products compare to one another and what types of application they're suited for? I see "well, plug 100 different parameters into Electricalc and you should get some idea...," then the next article says "Electricalc indicated this, but in reality, we found _____." I have a firm understanding of the battery/ wiring/ electronic aspect of this endeavor, but am really having a problem coming to grips with the motor/gearboxes/prop combos portion. If anyone can suggest websites, books, etc. that might help, it would be greatly appreciated!
Thanks...Fred
Thanks...Fred
10-11-2002, 04:01 PM
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Typical Newbie Question???
When you find it let me know!!!! 
Now having said that, the best source right now for getting all the MANY variables in line to give you an idea of what will work is by using a computer program similar to Motocalc.
While the "real world" numbers may vary from what the computer program tells you, the program will give you a reasonable idea of what to expect.
As an example: If you use Motor X with ESC Y and Battery Z, you will get better speed/efficiency/runtime/whatever than if you use Motor A with ESC B and Battery C, and so on. It's experimentation at the computer level before you buy equipment.
Most battery, motor, and ESC manufactures will post the necessary information about their products to allow you to plug these values into the computer program.
This is the best way IMHO at this time to test various "senarios" to get the "optimum" performance you are looking for.
Also, a while back, Aveox had a brochure which gave some meaningful calculations for performance. You might see if you can find one of them. I bought mine at SEFF for 50 cents.
Good Luck.
Now having said that, the best source right now for getting all the MANY variables in line to give you an idea of what will work is by using a computer program similar to Motocalc.
While the "real world" numbers may vary from what the computer program tells you, the program will give you a reasonable idea of what to expect.
As an example: If you use Motor X with ESC Y and Battery Z, you will get better speed/efficiency/runtime/whatever than if you use Motor A with ESC B and Battery C, and so on. It's experimentation at the computer level before you buy equipment.
Most battery, motor, and ESC manufactures will post the necessary information about their products to allow you to plug these values into the computer program.
This is the best way IMHO at this time to test various "senarios" to get the "optimum" performance you are looking for.
Also, a while back, Aveox had a brochure which gave some meaningful calculations for performance. You might see if you can find one of them. I bought mine at SEFF for 50 cents.
Good Luck.
10-11-2002, 04:59 PM
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Typical Newbie Question???
When figuring out an electric power system, the motor is the last thing you need to worry about. The important thing to figure out in an electric power system is the number of Watts you need to fly the airplane. From there, figuring out which pieces you need is a simple exercise based on budget and personal preference.
A plane needs a minimum of about 35 Watts per pound (W/lb) of weight to maintain level flight. You need 50 W/lb to ROG from a smooth surface and fly circuits. You need 65 W/lb to ROG from a grass field and fly basic loops and rolls. 80 W/lb will give you typical sport plane performance. 100 W/lb or more will leave you slack-jawed in amazement
The hardest part is figuring out what the airplane will weigh, completely finished with motor and battery. A good starting point is the manufacturer's specifications. If this is a glow conversion, figure 15%-20% over the manufacturer's specs for final weight, unless you plan on doing some serious lightening. From here, it's simple multiplication to figure out how many watts you need to power the airplane.
Next, you figure out how many cells you need in the battery. For most planes in the .15-.60 size range, a maximum current of 25A-35A should be used. This minimizes the abuse you subject your equipment to. A 6lb plane powered with 80 W/lb requires 480W of power. At 30A, this means I need 16V (W = V * A). Figuring 1V per cell, this means the plane should fly well on 16 cells.
A plane needs a minimum of about 35 Watts per pound (W/lb) of weight to maintain level flight. You need 50 W/lb to ROG from a smooth surface and fly circuits. You need 65 W/lb to ROG from a grass field and fly basic loops and rolls. 80 W/lb will give you typical sport plane performance. 100 W/lb or more will leave you slack-jawed in amazement
The hardest part is figuring out what the airplane will weigh, completely finished with motor and battery. A good starting point is the manufacturer's specifications. If this is a glow conversion, figure 15%-20% over the manufacturer's specs for final weight, unless you plan on doing some serious lightening. From here, it's simple multiplication to figure out how many watts you need to power the airplane.
Next, you figure out how many cells you need in the battery. For most planes in the .15-.60 size range, a maximum current of 25A-35A should be used. This minimizes the abuse you subject your equipment to. A 6lb plane powered with 80 W/lb requires 480W of power. At 30A, this means I need 16V (W = V * A). Figuring 1V per cell, this means the plane should fly well on 16 cells.
10-23-2002, 02:21 AM
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Typical Newbie Question???
ac5tf, I came to this site for the same reasons and questions as
you. As a 20 plus year fuel driver, pattern etc. I would like to look into the Elecs. Mkirsh, you are a great help, more than I have been able to come up with yet. BUT, is there any way to find out
the amount of thrust from a given size elec? Are there comparisons of power to fuel engines say like .020, .049, .09 etc.
I was given an old Sky scooter and thought I might repower it to
get familiar and learn some of the basics of powering. Tower lists
T-400GD with ESC, and T-600 with ESC with gear drives. How am
I to know which is best in this 2LB. +- plane for good sport performance?
you. As a 20 plus year fuel driver, pattern etc. I would like to look into the Elecs. Mkirsh, you are a great help, more than I have been able to come up with yet. BUT, is there any way to find out
the amount of thrust from a given size elec? Are there comparisons of power to fuel engines say like .020, .049, .09 etc.
I was given an old Sky scooter and thought I might repower it to
get familiar and learn some of the basics of powering. Tower lists
T-400GD with ESC, and T-600 with ESC with gear drives. How am
I to know which is best in this 2LB. +- plane for good sport performance?
