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Howto:Creating 3D instruments: Difference between revisions
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[[Image:Fokker50_prop_browser_screenshot1.jpg]] | [[Image:Fokker50_prop_browser_screenshot1.jpg]] | ||
Now, we have a slight problem at this stage; the fokker50 was created before JSBSim could model turboprops, and so the ITT property is not available right now. For the purposes of this tutorial though, we'll just use the exhaust temperature instead; the process is what's important. | |||
So, the next line in our XML file will be specify the property to use; | |||
<property>engines/engine/egt_degf</property> | |||
Next we need to specify exactly how much that property moves the needle. There are several ways to do this, but we'll use a simple interpolation table since these are especially useful in more complicated situations. The ITT gauge is marked from 0 degC to 1200 degC; since we're having to use a value that's reported in degF for now, we'll just convert those two values. 0 degC is about 32 degF and 1200 degC is about 2192 degF. Two handy tips here; for Linux/unix users, the "units" program is truly invaluable; for everyone, google has a useful units converter; for example search for " | |||
1200 degrees celsius in fahrenheit" | |||
On to our table then. | |||
<interpolation> | |||
<entry><ind>32</ind><dep>0</dep></entry> | |||
<entry><ind>2192</ind><dep>230</dep></entry> | |||
</interpolation> | |||
The <ind> entries are what's indicated on the gauge; the <dep> entries determine how many degrees the object will be rotated by. I found that number by rotating the needle in AC3D from one end of the scale to the other and reading off the rotation value reported (see screenshot) | |||
[[Image:Fokker50_rotation_value.jpg]] | |||