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Feb 15, 2013, 10:55 PM
Registered User
Mini-HowTo

How can I tell the propeller direction?


Hello, I have a very newbie question. When you put a propeller on your motor, how can you tell which way is 'forward'? Forward as in facing the flight path.
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Feb 15, 2013, 11:32 PM
Registered User
If there is any text on the prop (size markings etc.), the text side should face forward.

To verify: the blades have an airfoil shape - one side is essentially straight and the other has a noticable convex curve. The curved side should face forward.
Feb 15, 2013, 11:33 PM
Wake up, feel pulse, be happy!
Piece's Avatar
Generally, the numbers and lettering will be on the front face of the prop. This applies to APC, GWS, Master Airscrew, Graupner, Xoar, GM, Zinger, Top Flite, and most other brands, but there are a few oddballs.

The most foolproof way is to determine which side of the prop is the convex side. The blades' convex faces always, ALWAYS face forward. Somebody here has a nice little image that shows the concept pretty well. It'll probably get posted soon.
Feb 15, 2013, 11:34 PM
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Piece's Avatar
...

Jkettu posted while I was typing... and, incidentally, posted almost exactly the same thing.
Feb 16, 2013, 10:26 AM
Registered User
Ginohio's Avatar
Quote:
Originally Posted by C₄H₁₀
Generally, the numbers and lettering will be on the front face of the prop. This applies to APC, GWS, Master Airscrew, Graupner, Xoar, GM, Zinger, Top Flite, and most other brands, but there are a few oddballs.

The most foolproof way is to determine which side of the prop is the convex side. The blades' convex faces always, ALWAYS face forward. Somebody here has a nice little image that shows the concept pretty well. It'll probably get posted soon.
Here ya go.
Feb 16, 2013, 04:47 PM
Wake up, feel pulse, be happy!
Piece's Avatar
Yup, that one
Feb 17, 2013, 10:38 PM
Registered User
aurorae's Avatar
After you put the prop on correctly, if the motor runs backwards, if you have a brushless motor just swap any 2 of the 3 wires.
Feb 18, 2013, 09:30 AM
Registered User
What most people do not realize is that a prop mounted backward, but turning in the correct direction, will still push/pull air in the correct direction, but the quantity of air pushed/pulled will be greatly reduced. I have seen a model takeoff, with the prop unknowingly mounted backward. The plane was extremly sluggish, but it did fly.
Feb 18, 2013, 10:28 AM
Redacted per NSA "suggestion"
dedStik's Avatar
Simple method.

A boat going backwards cavitates. The backside of a plane propeller is concave, the word "cave" appears in both cavitate and concave.
Feb 20, 2013, 12:29 PM
Shelter Kitty "Orange Death"
bartricky's Avatar
Quote:
Originally Posted by dedStik
Simple method.

A boat going backwards cavitates. The backside of a plane propeller is concave, the word "cave" appears in both cavitate and concave.
I remember it by "you can always go into a cave"
Feb 20, 2013, 01:26 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by dedStik
Simple method.

A boat going backwards cavitates. The backside of a plane propeller is concave, the word "cave" appears in both cavitate and concave.
I hate to be a party pooper but 'cave' doesn't appear in 'cavitate'... At least not unless you jumble the letters around a bit
Feb 21, 2013, 08:45 AM
Registered User
Quote:
Originally Posted by JetPlaneFlyer
I hate to be a party pooper but 'cave' doesn't appear in 'cavitate'... At least not unless you jumble the letters around a bit
there you go pooping on the party again
Feb 21, 2013, 09:10 AM
Redacted per NSA "suggestion"
dedStik's Avatar
/me passes the tp

The root 'cav' is close enough to work as a mnemonic device.

I'm just glad I didn't misspell it and write cavities.
Feb 27, 2013, 04:30 PM
Registered User
Sorry about the late post, I've been crazy busy with a new job. Good to know and thank you all.
Feb 28, 2013, 05:29 AM
Suspended Account
Propellers are described as left- or right-handed. Left-handed propellers rotate counterclockwise and are known as "counter-rotating propellers." When the boat with a left-handed propeller backs up, it pulls to the left. When a boat with a right-handed propeller backs up, it pulls to the right.
nstructions
1
Look at the propeller mounted on the motor. When seen from above, the leading edge of a right-handed propeller is to the right of its trailing edge. The leading edge of a left-handed propeller is to the left of its trailing edge.

2
Start the motor and watch, from astern of the motor, the direction in which the propeller turns. A left-handed propeller rotates counterclockwise; a right-handed propeller rotates clockwise.

3
Put the boat in reverse, turn the motor so that it's centered and back the boat up at idle speed. If the stern pulls to starboard, the right side of the boat, it's a left-handed propeller. If it pulls to port, it's right-handed.


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