after playing this game for about 2 weeks now I think i have a rather firm grasp on what propeller pitch does, more specifically 109's, cus that's what I spend most of my time in.
Quote:
|
Originally Posted by Albert Einstein
You do not really understand something unless you can explain it to your grandmother.
|
So, IMHO, this is how I would explain propeller pitch to my grandmother.
Since I ride my bike to classes everyday, I'd like to compare propeller pitch with a bike that has gears.
So when you start from a stop on ur bike, you'd want to start with a low gear, which corresponds to 12:00 pitch in 109.
As you start to pedal harder and start to accelerate, you will eventually reach a point where u're pedaling very fast but not going any faster, in other words, the wheels now go faster than you can pedal. This condition corresponds to when you're in straight level flight and your engine is at almost 2500 RPM.
Now on a bike, you need to shift your gear up and you will immediately feel the force on the pedal and with relatively little amount of force, you can go faster. In our 109 counterpart, you would coarsen/decrease the prop pitch to make the blades catch more air, as a result, the engine's RPM goes down, with relatively little stress on the engine, the airplane goes faster.
Same analogy applies to climbing a hill/gaining altitude.
On a bike when you're trying to go uphill with some initial velocity, at the bottom of the hill, you would opt for a high gear to use off the remaining inertia, and then work your way down on the lower gears to maintain a optimum pedaling force. Towards the top of the hill, you would probably be in a low gear and pedaling very fast just to keep going.
In our airplane counterpart, as you start a climb from level flight, you start from a coarse pitch, depends on how fast your initial velocity is. Then as you gain more altitude, you slowly increase your propeller pitch to maintain the optimum engine RPM, between 2100 to 2400RPM. Towards the top of ur climb, you will be in a very fine pitch close to 12:00.
Please, everyone, feel free to point out anything you find incorrect. I wrote this to offer my own perspective on propeller pitch to help people who still don't understand it.
Lololopoulos