Photle

Hey.

As a flight instructor in training I'm trying to get a good grasp as possible on the things I have to explain to my students.

One of these things, that are not really practiced in ground school or in any other aspect of flight training is electricity.

Basically I'm trying to explain the avionics and electrical system of an airplane. Involved in these schematics and numbers are terms like amperes, ampere-hours and volts.

Now I've had some degree of physics in high school, and a general like for electricity in my childhood so I think I understand enough of it to get a grasp myself, however, I do not really have a good enough understanding to teach it. Therefore I'm trying to come up with good analogies and explanations for the questions that might arise, and to be able to explain to a student with no previous experience with electrical terms to at least get a basic understanding of it.

For analogies using amperes and volts, I usually use the "garden hose analogy", where volts is the pressure, and ampere is the actual flow of water, you can also say the size of the hose is resistance, but that's not really covered in any aspect of flight training.

Now onto the questions, can people help me explain these things:

1. Why do an electrical system - that includes a battery and an alternator - have the alternator at a higher voltage than the battery.

Example: in one airplane you have the alternators running at 14V and the battery at 12V. My logical answer would be that the battery needs to run at a lower voltage to be charged when the alternator is running, but why does the battery only charge when it's at a lower voltage if that's the case?

2. What is a solenoid? In many electrical diagrams in airplanes I see the term solenoid being thrown around, but I've never actually figured out what their purpose is

3. Can you say that the voltage is what determines how much electricity can potentially flow in a system? If yes (or if no), why do electrical systems in cars and airplanes run at a relatively low voltage like 12 or 24. Wouldn't the electrical system be more effective at a higher voltage like triple digits?

Would a 12volt system run through a specific circuit have a limit on the amount of amps it could carry in relation to a higher voltage system?

4. An alternator produces amperes (a measure of electrons passing by a given point over a given time, right?), however, overvoltage from the alternators is always a concern in airplanes. What causes an overvoltage, and what in itself determines the voltage in an electrical system, and how can you change or set the voltage in a circuit?

Finally, why is a higher voltage bad for an electrical system, and what is the damage potential and causes?

5. Demand. How does an alternator, or a device connected to an electrical circuit draw power?

Say you have a device connected to an alternator that at its peak can generate 60 amps. The device only needs 10 amps.

Will only 10 amps flow through the circuit? Or will 60 amps flow through and only 10 of them be used (same example, only a normal household outlet, same result?).

How does the alternator "know" how much electricity to produce to the devices connected, do they actually "draw power" through the circuits in some way?

Hope these questions are not all to far off, and thanks for any answers you guys might have!

I'm going through my MEI course at the moment, and as an instructional aid I'm trying to find a die cast metal light twin airplane, like a seneca, seminole or the likes.

However I can't find one anywhere for a decent price, just senecas for like $150 etc.

Does anyone know of any diecast light twin for under 20 bucks?

In regards to air units, like fighters that have 4 moves and bombers that have 6 moves.

Do they get to move to a land 6 tiles away, attack, and then retreat an additional 6 tiles? or can they only move 6 tiles in one turn?

I can't really seem to find a reason why the GPS-airways should have an MAA.

I've asked lots of instructors and fellow students, with no luck..

Basically it can't be because of jet airways, as they start at 18 000 at the very least, and the gps signal should be good a lot further up than just 15 000?