Common Questions with Fan Jets USA

Matt Hague shares information about Fan Jets USA

By Jay Smith [email protected] | Photos provided by Fan Jets USA

As seen in the May 2023 issue of Model Aviation.

When did Fan Jets USA open for business?

Fan Jets USA started operations in 2009, specializing in EDF jets and the accessories needed to operate them. Our focus is selling high-quality and performance parts. Whether it is for a composite or foam EDF jet, we can upgrade the performance.

I got into the business because I have 36 years of RC flying experience, spanning various types of models, from electric-, nitro-, and gas-powered sport, to scale, and jet aircraft.

Are all EDF units the same?

The construction and materials used will significantly impact the performance and air movement going through it. The standard EDF units in ARF/PNP kits are made from common nylon plastic material. This material will allow the rotor and the outer housing to warp, decreasing the efficiency and thrust output.

Higher-performance EDF units will be made from carbon fiber or aircraft-grade T6 aluminum. The stiffer the EDF unit is, the more air it can push through, making the EDF unit more efficient and producing better thrust.

Both the rotor and outer housing of the EDF unit are important for thrust production. The E-Jets Jetfan, Schübeler, and JP Hobby EDF units are high-end EDF units because they are lightweight and stiff.

What is the maximum rpm and the most efficient rpm at which to run?

The maximum rpm will vary by EDF class size. Exceeding the recommended rpm can cause the rotor to explode and cause damage to the airplane and possibly bystanders if it is on the ground.

Another reason to not exceed the recommended rpm is that the efficiency of the EDF unit will go down. It might rotate faster, but that doesn’t mean that more air will be pushed through the EDF unit. In the 70mm class, the maximum rpm is 50,000; for the 80mm to 90mm class, it is roughly 47,000; and for the 100mm to 120mm class, it is 38,000.

I want to go faster; Can I just use a higher-voltage battery?

When increasing the cell count of the battery used in the airplane, there are factors to consider. Can the current motor or the motor that you plan to purchase run on the intended voltage? Brushless motors are designed to operate on specific volts. If you have a motor designed to run on a 6S or 8S LiPo, using a 10S LiPo will not work because it would be too much voltage and burn up the motor.

The size of the EDF jet also needs to be taken into consideration. Using a larger battery can actually hurt the performance of the jet. RC EDF jets are sensitive to weight and the wing loading can quickly increase, hurting the flight characteristics. Higher-voltage batteries are not always better.

For example, a 90mm EDF jet is designed to run on a 6S or 10S LiPo battery with an 8S LiPo being optimum. Putting a 12S LiPo in the airframe can cause a higher wing loading, plus issues with balancing the model, which, in turn, requires more weight to balance it out.

The 100mm to 120mm class is designed for 12S to 14S power, and for the 70mm class, a 3S to 4S LiPo is typically used. Instead of increasing the voltage, consider changing the motor for another one that has a higher Kv.

Does the rotor blade count matter?

A rotor with a low blade count can perform just as well as one with a high count. The main difference is the sound that is produced. A higher blade rotor count will produce more of a sound similar to a turbine. Rotors with a blade count of 9 to 12 blades will sound indistinguishable.

Why should I consider upgrading the motor from the stock one that came in the airplane?

Motors that come with ARF EDF jets do not have the power or the efficiency of a higher-performance motor. Typically, when a customer puts in a High End Technology motor, the watts and amp draw drop and flight time is increased because of the efficiency of the motor, without sacrificing rpm.

I have some 70mm EDF jets without landing gear and I can’t hand-launch them. Do you offer an alternative?

The Jetapult was designed by Fan Jets USA for this reason. Capable of launching 64mm to 90mm EDF jets, it is a safe and reliable way to get jets up in the air. Adjustable to fit a variety of EDF jet sizes, it features hands-free operation so that the pilot can keep both hands on the transmitter for safety.

What ESC programming is best?

When setting up an ESC, you want to have the brake off and soft start selected. Timing is dependent upon the manufacturer of the motor. Using a wattmeter is also very important to make sure that the motor is not being overdrawn with watts and pulling too many amps, which can damage the motor. If the watts are too high, lower the timing or reduce the end-point adjustments of the throttle.

Does Fan Jets USA offer services to install the motor into the EDF unit?

We do offer the services of soldering gilt/bullet/battery connectors onto motors and ESCs that are purchased from us. Installing motors into the EDF unit can also be done.