Propeller Tuning

From all of the stock means of airplane propulsion, propellers are arguably the most complex to set up efficiently. Propeller performance changes with settings, power source and flight conditions. Tuning a propeller for an inexperienced player may pose a challenge. There are serval methods to consider all of which have their own tradeoffs.

Propeller configuration

Before the propeller in question can be tuned, one should first consider what kind of propeller should be used.

Propeller type

There are serval different propeller types to choose from, each behaving slightly differently than the rest. For information about specific types see Propellers#Propeller_Types.

Blade scale

One of the most important settings of your propeller. Bigger propellers can potentially produce more thrust but not without tradeoffs. Bigger propeller has a higher moment of inertia, meaning that those will spin up and down much more slowly than their smaller counterparts.

Another thing to consider is that larger propellers reach lower rotational speed before hitting Mach 1. That is a problem for propellers other than the supersonic one. Hitting supersonic blade tip speeds significantly lowers efficiency and thrust.

Blade count

Apart from the size, players can also choose the number of blades their propellers have. It can range from 2 up to 12. More blades can potentially provide more thrust but will also require more torque to keep spinning at the same speed.

Tuning the gear ratio

To achieve the most thrust, one should tune the gear ratio so that when the engine reaches redline, the propeller is just about to reach Mach 1.

The easiest method to do just that is to set the blade angle offset to 0 and apply full throttle. The engine should reach its highest rpm value. After that, the gear ratio should be set to such a value so that the output from the propeller is at about 0.99 (It's much easier to see if the output is connected to a display with a decimal offset of 2).

Tuning the blade angle

Constant blade angle

How to

1. Apply full throttle.
2. Set the blade offset angle so that the propeller slows down a bit (if that angle is higher than 45 degrees then you probably want to use a bigger propeller or a propeller with more blades).
3. Gradually decrease that angle until the engine is just about to reach max rpm.

By following these steps, the propeller will reach the highest efficiency when the vehicle is standing still. It helps with takeoff but the thrust will diminish at higher speeds. If you want to trade takeoff performance for max speed then you could add 1 or 2 degrees to the blade angle offset.

Pros

• Quite simple to tune
• Requires no further attention from the pilot once set up

Cons

• Only efficient at specific airspeed

Manual blade angle

How to

1. Set the blade angle offset to something low like 0 and the input multiplier to 1.
2. Attach a shift box and wire its input to an axis or button axis output of a seat. Then wire the shift box output to the propeller logic input.

Set the speed of the shift box so that you feel comfortable adjusting it during flight.

Pros

• Simple to make
• Can be adjusted mid-flight according to the situation
• Can be efficient at any speed

Cons

• Requires the pilot to change the angle whenever the plane's speed changes in order to keep the propeller at highest possible efficiency

Automatic blade angle

Pros

• Requires no attention from the pilot once set up correctly
• Can potentially adjust to any speed

Cons

• Is a little bit more complicated to set up than the previous methods