Well it sure is not me!! It's like I am in a time warp or something, back to 1999![sm=confused.gif]

I am only dealing with the reality at the AMA as I understand it to be. In truth the thing that causes high speed potential is the turbine's high efflux velocity, maybe 450-500+ miles per hour. A little P-60 in a Stingray would probably go over 200.

The worse thing they could do is limit thrust, and limit speed without a speed limiter. Then we would not have enough power to fly the big draggy planes. I watched a friend fly a Eurofighter with a P-120, it flies good, but it needs every ounce that motor puts out. I doubt it would be very fun at 22 pounds of thrust.....


As for the speed sensor on the JetCat, yes it is integrated. For you new guys, there was even talk when the speed limiters were first discussed in 1999, that they would HAVE to be integrated, but someone backed off of that.

The speed sensor really has 3 technical elements, each that have to be handled correctly (most of the following meant for lurkers/newbies, not the veterans).

1.) The Dynamic/Static ports. The system has to fundamentally measure the difference of the dynamic pressure of the aircraft moving through the air mass, and the local ambient pressure. In order to do this, one port is configured to be pointing into the relative wind. THe other port is much harder to locate. I have seen other systems that vented the static port (that measures ambient pressure) into the fuselage or something....not always a good choice if pressure or negative pressure is generated in the fuse while the plane is flying. Another option is to mount the static port on the pitot tube itself, in a double wall arrangement, with the static ports located about 5X diameters of the dynamic port back from the pitot face...that is how we do it on the JetCat unit. As Mike and Tony have said, the installation of this port is most critical for the overall system accuracy. I have used the port in the nose (best results) to the vertical fin (also very good) to the little molded standoffs on the fuse (not as good)

2.) The Transducer. This is the little device that converts the pressure difference from the dynamic /static ports into a voltage proportional to the speed. We use a temperature compensated monolithic sensor from Motorola. It's full range is about 2 PSI (I think), and it has pretty good performance characteristics. IMHO, it does not add a significant error to the system.

3.) The Controller. This is the part that actually changes the power setting on the turbine to try to control the speed of the aircraft based on the inputs from 1.) and 2.), above. My guess is that this is where the other third party system is not behaving well. You really need to follow some design rules to have a decent response of this control algorithm. We run a full Proportional, Integral, Derivative (PID) control loop. This is a pretty standard control technique, we use similar loops to control the turbine in normal thrust mode. We also limit the amount of range the controller has on the low end, so you do not get that sudden pull back of the throttle to idle that a "bang-bang" controller might have. We can also tune some settings for better performance with different weight and drag coefficient airframes. I do not see why this same technology could not be put into a third party controller.