Speed Control Devices
Let's Use Them
by Bob Violett

The Academy of Model Aeronautics and the Jet Pilot's Organization established a 200 mph limit for turbine powered models.

This velocity limit is specific to turbine powered model aircraft because the potential for speed is almost without limits and the fact that high energy crashes can result in a fire.

The dynamic forces on a model increase radically with speed.  As these forces increase, so does the need for more strength and integrity of the component parts of the machine.

The experience required to thoroughly check and maintain these components to safely sustain excessive speed is beyond the scope of most hobbyists.

During the flight testing stage, and before we sell a new BVM jet product, we employ the Eagle Tree Telemetry System and the JetCat Airspeed and GPS System to record speed and "G" forces.  We found it quite revealing to really know the speed and "G"s a turbine model can experience.

The speed of a large jet is deceptive to our "model airplane senses".  For instance, a high speed pass with a 96" long Ultra Bandit might appear to be in the 200mph range when in reality, the telemetry device records 230-240 mph.  We also know that an aerodynamically clean model jet with a high thrust-to-weight ratio can attain 300 mph or more.

So, unless your senses are finitely calibrated to exactly determine the 200 mph limit and your throttle management technique is tuned accordingly, I strongly suggest that we use the technical devices at hand for safety reasons.  These devices are also of great benefit for precision approach and landing information and control.

High Tech Tools for High Tech Pilots
The JetCat Accessories


GPS

 


JetCat Air Speed Sensor

 

Eagle Tree

If your brand of E.C.U. does not have a speed limiting capability, the Eagle Tree System will provide a live readout of airspeed, altitude, temperatures, etc..  Have your helper call out the speed or listen for the warning tone on the "Dashboard".

 

Absolute Perfection Required

For an airframe to be able to operate safely at high speed, every component must be in perfect working order.  The higher the speed, the lower the tolerance for imperfection.

The list of possible mechanical or electrical imperfections that could be lingering in your model is almost endless, but here are a few examples:

     A critical bolt is mistakenly cross threaded.

    A threaded rod was bent too far and is partially fractured.

    A servo gear or output arm spline can be stripped by improper handling.

    A control linkage is not properly designed.

    Upgrades in servo power were not matched with increased safe amperage supply.

    Transportation or hard landing damage was not thoroughly inspected, discovered, and properly repaired.

BVM stocks the JetCat and EagleTree equipment.

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