Bell Electronic Technologies
4330 Old Pine Court
Etna, California 96027-9518
Accurate to .01 Degrees
Easy to install
Easy to use
No power required
"Set Zero" feature eliminates the need to level the model
Incidence Meter bracket needed to measure incidence.
I'm not much of a "Gadget Guy"; I mean, why buy a special tool for opening a clevis when a screwdriver (which is already in my inventory) will do the trick? But I certainly can appreciate a good product when I see one. Such is the new MU-9000X USB from AeroPerfect. The MU-9000X is a precision angle-measuring device that is accurate to .01 degrees in two axes simultaneously. It can be used to measure any angle on your aircraft easily and accurately. The angle-sensing unit contains a dual-axis, absolute inclinometer that utilizes MEMS (micro electro-mechanical systems) technology to accurately measure angles over the entire 360° range.
The MU-9000X sensing unit plugs into a USB port on your computer and the provided software displays an easy-to-read window. If you don't have a computer close to your shop, you could purchase the MU-9000X AP3, which uses the same MU-9000X measuring head, but it also has its own digital LCD display unit.
If you already own an incidence meter, the MU-9000X can be attached to the meter's bracket for a more accurate measurement with a digital readout (so no more guessing when the meter's needle is between numbers).
The MU-9000X is an excellent way to get precise measurements on incidence, decalage (The difference between wing and stab incidence) and control throws. But what, you may ask, if my plane's control throws are measured in inches or millimeters? No problem! A built-in converter does all of the math for you and gives you a "Target Angle" to shoot for.
But that's enough talk. Let's dig in!
The MU-9000X USB is an absolute inclinometer utilizing MEMS (micro electro-mechanical systems) technology to sense tilt angles over a full 360° range in 2 axes. The MU-9000X USB incorporates a number of patent pending breakthroughs to create a new type of inclinometer that is rugged, compact, fast, lightweight and easy to use. The MU-9000X USB represents leading-edge advancement is MEMS technology and is the most advanced device available for radio control aircraft setup.
A USB to RS232 interface is included which facilitates communication between the MU-9000X USB and the pilot's computer / software. The interface is USB 1.1 and 2.0 compatible and the included 6-foot cable is ROHS compliant. Configurations and parameters are stored in non-volatile memory within the MU-9000X measuring unit and include level, resolution, damping / averaging time, and direction. Damping is the amount of time over which angle readings are averaged and is adjustable according to user preference from 2 to 5000 milliseconds.
The MU-9000X USB software runs on laptop or desktop computers running either Windows Vista or Windows XP. A minimum of 5.83 Mb of disk space is required.
Measured Angle Frame, Measurement Frames 1 and 2: This frame shows the measured angle. The angular range is +/- 180 degrees (360 degrees total).
Large Digit Display Button: When selected, the display shows the measured angles for both Measurement Frame 1 and 2 in Large Digits. Can be selected from either Measurement Frame 1 or 2. To return to the main screen, click on the "Back to Main Screen" button.
Zero Button, Measurement Frames 1 and 2: When selected, the Measured Angle Frame is set to zero degrees. This relative zero can be set at any angle.
Level Button, Measurement Frames 1 and 2: When selected, the software reads the factory-calibrated level. Now, when the Measured Angle Frame reads zero, the measurement plate is level.
+ Target / - Target, Measurement Frames 1 and 2: These frames hold the desired or "target angles". When the angle shown in the Measured Angle Frame equals the "target angle", the corresponding color bar illuminates green. The angles within the +/- Target Frames can be keyed in manually or the angles can be loaded in automatically using the "Conversion Utility" (see below). Be sure to key in the minus (-) sign when entering negative numbers.
Target Tolerance Drop-down Menu, Measurement Frames 1 and 2: The angle selected in this menu determines how close the measured angle must be to the "target angle" before the corresponding color bar illuminates green. For example, if .25 degrees is selected and +22.00 and -22.00 are chosen to be the "target angles", then the angle ranges that will cause the two color bars to illuminate green are +21.75 to +22.25 AND -21.75 to -22.25, respectively.
Axis Select Drop-down Menu, Measurement Frames 1 and 2: Either Measurement Frame (1 or 2) can be set to Axis 1 or 2.
Picture Drop-down Menu, Measurement Frames 1 and 2: Either "Pitch" or "Roll" can be selected as the Measurement Frame Picture. The "Pitch" and "Roll" pictures appears as either an airplane or a representation of the disk-shaped measurement device. Either airplane or device can be chosen from within the "View" menu.
Invert Button, Measurement Frames 1 and 2: When selected, the polarity of the Measured Angle frame changes. The Pitch or Roll picture will also rotate in the opposite direction when "Invert" is selected. This feature allows the USB cable to more easily egress in a desired / convenient direction.
Convert Button, Measurement Frame 1: This conversion utility allows control surface deflection that has been specified in inches, to be converted to degrees. Simply enter inches (or millimeters) of control surface movement into the right (+deflection) and left (-deflection) entry boxes, enter the width of the control surface into the center entry box (chord), and click the "Convert" button. Inches (or millimeters) are converted to degrees and loaded into the -/+ Target frames above. For more details about converting from inches to degrees, please visit our Tips Page.
+/-90 Degree Buttons, Measurement Frame 1: This feature facilitates convenient measurement of engine thrust angle. Similar to the "Zero" button (sets Measured Angle to 0.00), this button sets the Measured Angle to +/-90.00 degrees. The +/-90.00 Degree reference is usually set when resting on a longeron in preparation for measuring engine thrust angle (Up/Down). If there is no up/down thrust angle set in the airplane, then the Measured Angle will read 0.00. If there is some up/down thrust set in the airplane, then that angular measurement is read directly without having to add or subtract 90 degrees from your measurement. The +/-90.00 Degree reference can also be set in preparation for engine thrust angle (Left/Right). The fuselage is placed on its side with the reference taken from the firewall and the measurement made on the engine shaft. See the Tips Page for more tips on measuring engine thrust angle.
Damping Drop-down Menu: Adjustable from 2 to 5000 milliseconds, this sets the amount of time that the software averages the hundreds of angle readings per second. In a mechanical inclinometer, the arm and counter-weight that seeks the lowest point can be thought of as a pendulum. It is important to dampen the pendulum's oscillations so that a stable angle measurement can be made. 500mS (1/2 second) is a good initial setting.
Save to File: Selecting this allows pilots to keep track of each AeroPerfect configuration. Examples of configuration names: "GP Extra 300 Left Aileron" or "Pitts Python Upper Wing Incidence". Files can be saved as .CFG or .TXT. "TXT" is best when sharing configurations by e-mail with other pilots. The name of the configuration file just saved is displayed at the top (to the right of the "View" menu).
Open File: Selecting this allows pilots to load previously saved configurations. The name of the configuration file currently loaded is displayed at the top (to the right of the "View" menu).
Temperature: This displays the temperature of the MU-9000X measuring device. It is displayed in Celsius and Fahrenheit and reflects the internal temperature of the device. It is always a bit higher than ambient as there is a small amount of device self-heating.
Current Software Version: This is displayed at the very top of the application.
Connection Status: Shown just below "Current Software Version", this shows whether or not the MU-9000X is communication with your computer. When connected and communicating, it will show which COM port is being used. When not connected / communicating, the message, "Not Connected" is shown and the application is replaced by an aqua color field.
View Menu: The "View" menu provides a link to this web page.
Upper, Right-Hand Button: This exits the application when selected.
Supply Voltage Range:
Position Update Rate
0C - 50C, On Axis, 360°
Damping Time, User Adjustable
Measuring Unit Weight:
Total Weight Including Clamps & Plates
Measuring Unit Dimensions
The heart of the system is the MU9000X sensing unit. The unit has a soft, thin rubber backing to prevent scratching. AeroPerfect also provides two small clamps for attaching the sensing unit, and of course, the software disc.
Setup is as easy as popping a disc into your computer and following the on-screen instructions - and there are very few. Mostly all there is to do is to press the "Next" button. AeroPerfect supplies a "Quick Start" guide to help you with installation if you need it.
Once the software is installed, connect the MU-9000X to any USB port on your computer and launch the software. You will now see a window that looks like this:
The window is split down the middle with similar readouts on each side to represent each of the two axes. You can now attach the sensing unit to whatever surface you want to measure. And since the MU-9000X measures both the X and Y axis at the same time, I actually used it to level my workbench before starting!
Once everything is ready, you can place the MU9000X onto the surface you wish to measure and hold it in place with the provided clamps. You will notice that the readout window shows that the elevator is reading a positive angle of 13.70°. This is due to the fact that:
A - The elevator is tapered and
B - The airplane is sitting on its main gear and tail wheel
Rather than having to level the airplane, all you have to do is to click on the "Zero" button and the software automatically sets whatever angle you're sitting at to zero. This feature alone is a huge time saver!
Also note how the helpful "Tool Tips" pop up when you hover your cursor over a button.
Now you can move the surface and get an exact reading of the angle of deflection.
Moving the surface in the opposite direction will give you a reading in negative numbers.
But my dimensions are in inches, not degrees. What do I do now?
Here is another great feature of the MU9000X USB. All you need to do is to measure the chord (width) of the surface and enter it in the box at the bottom of the screen (in inches or millimeters).
Next, enter the amount of deflection needed (again in inches or millimeters) in the boxes on either side. Since there are two boxes, you can even add different numbers for differential. Now just click the "Convert" button and two numbers will appear in the "Target" boxes on either side of the "Angle" box. Once your angle is equal to the target, you will have the correct amount of deflection.
Ok, that's pretty slick, but I'm mathematically challenged. How do I convert fractions to decimals?
This is one of those things back in Grade School that used to send shivers down my spine, but it's really very easy - especially now that we have calculators! So as a public service, here's a quick lesson.
Let's say you're looking to convert the fraction 5/8". Get your calculator and punch in the number one (1). Now, divide that by the number below the slash, which in this case is eight. You will get a reading of "0.125". That is one eighth. Next, multiply that by the number in front of the slash, which in this case is five. This will give you a product of "0.625". That is five eighths.
If you're still confused, here is a table that you can print out and keep in a safe place.
With the addition of a bracket from a wing incidence gauge you can use the MU9000X to measure incidence, or decalage (The difference between stab and wing incidence), or by just laying it on a surface you can check a plane's datum line or even the engine thrust line.
Last but not least, the MU9000X USB has two more handy features. With the click of your mouse, you can switch the window to show LARGE NUMBERS which can easily be seen at a glance, and once you have arrived at your settings, you can save them to reload at a future date!
As I said in the intro, I'm not much of a gadget guy, but I DO check things like wing incidence and control throws! Using the MU9000X makes doing these and other tasks much quicker and WAY more accurate. Its only downfall seem to be the lack of having its own bracket for measuring incidence, but if you already have an incidence meter you can use the bracket from that and if you don't, they're easy enough to make. I also think a hole in the mounting surface would have been nice so it could bolt directly to an engine's output shaft, but I guess it's just as easy to place it flat on the shaft.
All in all, I am very impressed with the MU9000X's accuracy. This is just one more fine example of how technology is keeping pace with our hobby!
Bell Electronic Technologies
4330 Old Pine Court
Etna, California 96027-9518