What do the numbers mean on a prop?

Asked By: Ilieva Zeidler | Last Updated: 12th April, 2020
Category: hobbies and interests radio control
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Numbers Stamped on the Propeller.
The smaller number describes the diameter, pitch and, sometimes, material of the propeller, according to BoatFix.com. The diameter and pitch can be separated by the letter "X," CompProp states.

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Similarly, what do the numbers on RC props mean?

All rc propellers are designated two measurements, both usually given in inches. The first number is the diameter of the imaginary disc ('arc') created by the spinning prop i.e. the length of prop from tip to tip. The second number is the pitch and this is the harder of the two to understand - but we'll give it a go

One may also ask, how do you read a RC propeller number? The first number is the prop's diameter. The second number refers to the prop's pitch or how much of a "bite" it takes as it revolves. The number indicates the theoretical distance the prop will advance with each revolution, assuming ideal conditions.

Besides, how do you size a prop?

The size of a propeller is defined with two sets of numbers, diameter and pitch, with pitch always following the diameter.

  1. Diameter. The diameter is two times the distance from the center of the hub to the tip of the blade.
  2. Choose the Right Prop for Your Boat.
  3. Cupping.
  4. Ventilation.
  5. Cavitation.

What is the difference between a 17 and 19 pitch prop?

The 17" prop will give you a better hole shot but lower top speed. If it is to small it the engine may go over the recomended top RPMs. The 19" prop will give you less of a hole shot but a higher top speed if the motor is strong enough to turn it in the recomended top RPM range.

32 Related Question Answers Found

What does the pitch of a propeller mean?

The pitch of a propeller is defined as "the distance a propeller would move in one revolution if it were moving through a soft solid, like a screw through wood." For example, a 21-pitch propeller would move forward 21 inches in one revolution. The same is true with a prop.

How do you calculate thrust on a RC plane?

Thrust = P X D^3 X RPM^2 X 10^-10 oz. The constant 10^-10 will have to be changed dependent on the prop and manufacturer. For GWS HD props the factor would be approximately 0.75. For props which have P/D ratios greater than 0.6 the equation is not valid for static thrust.

How do you measure thrust?

Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second.

How do you size a RC plane motor?

The maximum current and power is what determines how large of a prop and what size plane can be used with the motor. Simply multiply the current by the battery voltage to get power. The larger the propeller's diameter and pitch, the more current the RC electric motor will draw for a given RPM.

How do you calculate thrust on a propeller?

  1. Most general aviation or private airplanes are powered by internal combustion engines which turn propellers to generate thrust.
  2. F = delta p * A.
  3. force = (force/area) * area.
  4. pt0 = p0 + .5 * r * V0 ^2.
  5. pte = p0 + .5 * r * Ve ^2.
  6. delta p = pte - pt0.
  7. delta p = .5 * r * [Ve ^2 - V0 ^2]
  8. F = .5 * r * A * [Ve ^2 - V0 ^2]

What prop pitch is faster?

Pitch is the distance the propeller will move the boat after one revolution (not accounting for slip). A lower pitched propeller will create more power due to more engine RPMs, but the boat will move slower. A higher pitched prop allows the boat to move faster by travelling a farther distance with each rotation.

Does Prop diameter affect RPM?

A prop's two dimensions each affect performance in different ways. For every inch of change in prop diameter the RPM varies by about 500 RPMs (up or down) and every inch of pitch changes the RPM by approximately 150 to 200 RPM.

Is a 3 or 4 blade prop better?

A 3 blade propeller usually offers top speed performance while a 4 blade propeller provides maximum thrust and smooth cruising operation. Four blades have some features of their own, though. They often provide more lift at the stern which will help accelerate the hull, especially if it is stern heavy.

Will a stainless steel prop increase speed?

As a rule, a stainless-steel prop (assuming the correct pitch and diameter) will make your boat go faster — up to 2-3 knots on some boats. Stainless steel is stronger and can be made thinner, allowing more speed. Stainless steel also flexes less and keeps its shape at higher speeds.

Will a 4 blade prop make my boat faster?

"Often, a four-blade propeller is the ticket," says Meeler. "The additional blade area grips the water better, allowing for quicker acceleration." The greater blade area also lifts the hull more while underway, which minimizes draft.

Will a Yamaha prop fit a mercury?

Yes, a Yamaha prop can be re-hubbed for a Mercury but it should also drop onto a Mercury thrust washer too. If you like the Yamaha SWS II, you'll like the Mercury MIRAGEplus better.

How do I increase my bow lift?

Bow lift is leverage of your prop to the transom. A badly slipping prop is the main culprit for losing lift, and guesses at that motor height that's your biggest culprit. You increase lift by: Increasing leverage (jack plate) you can always put 2" extensions on what you've got, that will usually give you some more.

How are RC propellers measured?

Scale RC aircraft propellers are usually specified as diameter × pitch, given in inches. For example, a 5x3 propeller has a diameter of 5 inches, and a pitch of 3 inches. The pitch is the distance that the propeller would advance if turned through one revolution in a solid medium.

What does Overpropped mean?

Over propped means the engine cannot achieve its max rated RPM. Under propped means the engine reaches max RPM too easily ie: the boat doesn't go as fast as one would expect.

Is it bad to run an outboard engine at full throttle?

As long as you are propped correctly and can hit the upper end of the RPM range, [to run an engine at its maximum throttle all the time] is not a problem. Most smaller engines have two speeds, OFF and WOT. Very rarely does an engine wear out. Keep up with maintenance and you will be fine.

What is the best prop pitch for a pontoon boat?

A 24-pitch prop will ideally push 24 inches through the water in one revolution of the blade. In practice, slippage makes it a bit less than that. Lowering the pitch of the prop gives the boat more power and better acceleration.

What is WOT RPM?

Whenever you purchase a new outboard or boat, it's wise to perform a WOT RPM test. Every outboard and sterndrive motor has a WOT rating, as established by the manufacturer. The WOT rating is the RPM range the motor should achieve when running at wide open throttle.