The E-Zone FAQ

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1) Beginner issues

A101 Why fly electric?
A102 How do I get started?
A103 What kind of planes can I fly with electric power?
A104 How do I sign up for the AMA/MAAC?
A105 What Kind of equipment do I need?
A106 What special tools would I need?
A107 Can you suggest a few beginner setups?
A108 Are soldered or crimp joints better?
A109 What goes on which stick?

2) Safety 

A201 What safety procedures should I follow when flying?
A202 What is an arming switch?
A203 When should I use an arming switch?
A204 How much power will I lose? How much weight will I gain? 
A205 What is a fuse? Why use one? 
A206 What type of fuse should I use?
A207 How do I choose the fuse rating?
A208 How and where do I install the fuse?
A209 Are there any safety precautions for the motor battery?
A210 How do I fuse a brushless motor?

3) Batteries

A300 Battery Basics
A301 What's Volt, Amps, "C" rating, etc....?
A302 What are milli-amp hours?
A303 How fast can I charge my batteries?
A304 What is Nicad memory?
A305 What is Cell reversal?
A306 Should I cycle my packs?
A307 Can I deep discharge an individual cell safely?
A308 What is the discharge of a Nicad like?
A309 Black Wire Syndrome
A310 Low Tech Cell Matching
A311 What are the effects of series and parallel?
A312 What are NiMH batteries like?
A313 Can I use Lithium batteries for electric flight?
A314 What do the battery codes like SCR, AE mean?
A315 Is it safe to solder directly to batteries?

  4) Electric motors

A401 What does "breaking-in" a motor actually do?
A402 How do I break-in a motor?
A403 What does gearing do?
A404 How do I compare an electric motor to an IC engine?
A405 What are motor constants?
A406 What's the difference between Delta and Wye Brushless Motors?
A407 What is "timing"?
A408 How much should I advance a speed 400?
A409 How do I use the "speed 400 timing tool?"
A410 How much heat can our motors dissipate?
A411 How can I keep my motors clean?
A412 What is a sensorless motor/controller?
A413 How does a sensorless motor work?
A414 What do the motor names (Speed 400,600, 05, 25) mean?
A415 How do I do a "Water break-in" ?
A416 How do I measure motor constants ?
A417 Will this cheap Mabuchi 540/380 etc. be good for E-Flight ?
A418 How many capacitors do I need on my motor and what values ?
A419 Should I wire two motors in series or parallel?
A420 Where can I find some information on common brushed motor constants?

  5) Speed controllers (ESC's)

A501 How does a speed control work?
A502 What is the advantage of a High Rate Control?
A503 What is the best switching rate for a hi rate ESC?
A504 How does a motor brake work?
A505 What is a BEC and how does it relate to the speed control?
A506 What are the disadvantages of a BEC?
A507 What is a Cutoff?
A508 How long can I fly once the cutoff takes place?
A509 What is opto-isolation and what does it do?
A510 How do I disable the BEC on my speed control?
A511 Where does my BEC speed control plug in ?
A512 Can I control 2 brushless motors with one controller ?

 6) Propellers

A601 Why doesn't my Graupner folding prop extend all the way out?

7) Chargers

A701 How does charging current relate to capacity?
A702 How can I make certain my packs are fully charged?
A703 How does a peak (or delta peak) charger work?
A704 Will my charger work with Ni-MH batteries?
A705 Will a NiCad peak charger work with Lithium batteries?

  8) Model info

A801 What are the differences between Indoor, Slow and Park flyers?
A802 What are EDF models?
A803 What exactly are EPS/EPP/Depron and other construction foams ?
A804 What is the watts/pound rule?
A805 What does the Watt-hours/pound rule tell me?
A806 How do I match an electric power system to a given airframe?
A807 How do I convert a gas powered plane to electric?
A808 Are there any proven electric setups listed anywhere?

 9) Electrical formulas

A901 How do I calculate duration?
A902 How do I calculate Watts?
A903 How do I convert units of measure?
A904 What is Orme's Law?

Reference  resources
Mailing lists 
FTP sites 
Web pages 
Non-electronic Resources 

Contributor Credits


 What is Orme's Law?


Q. What is Orme's Law?
A. Jim Bourke, originally developed by Mathew Orme.

Use one cell for every 35 square inches of wing area for sport planes. One cell for every 50 square inches of wing area for trainers.

This rule is the work of Matt Orme, who manages the sales of Aveox’s line of motors to the hobby market. Matt wanted to come up with a simpler way to recommend systems to the many people who ask him for advice powering their models. Brushless motors are very versatile and it can be hard for newcomers to decide which system they should use. Matt’s rule makes system selection pretty easy. Orme’s law assumes that the hobbyist will be using 1700 to 2000 mAH cells and will prop for 4 minutes of flight, or 30 amps. If not, then further calculations need to be performed. Take a look at the rule using my Citabria Pro, which has 560 square inches of wing area. According to Orme's law, we need exactly 16 cells. It just so happens that I power the airplane with 16 cells, exactly as Orme's law predicts. But, when I chose the power system, I went through a lot more work. First I used the wing area and wing loading goal to determine the weight. Then I picked a power loading and duration goal to calculate the number of cells. Then I determined the weight of the cells and subtracted that from the finished target weight. Then I created a weight budget for the model as I built it. Then I overshot the weight budget and added a couple of cells. Then I spent a bunch of time rearranging stuff in the belly of the plane to make 16 cells fit without messing up the CG. I went through a lot of work and only got back to where I would have been with a simple calculation!

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