So orbiter was unzipped to c: drive.
i found 2 of these:
<?xml version="1.0" encoding="utf-8"?>
<Project DefaultTargets="Build" ToolsVersion="12.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ImportGroup Label="PropertySheets">
</ImportGroup>
<PropertyGroup Label="UserMacros">
<OrbiterDir>c:\Orbiter2016\orbiter</OrbiterDir>
</PropertyGroup>
<PropertyGroup>
<_ProjectFileVersion>12.0.21005.1</_ProjectFileVersion>
</PropertyGroup>
<ItemDefinitionGroup />
<ItemGroup>
<BuildMacro Include="OrbiterDir">
<Value>$(OrbiterDir)</Value>
<EnvironmentVariable>true</EnvironmentVariable>
</BuildMacro>
</ItemGroup>
</Project>
<?xml version="1.0" encoding="Windows-1252"?>
<VisualStudioPropertySheet
ProjectType="Visual C++"
Version="8.00"
Name="orbiterroot"
>
<UserMacro
Name="OrbiterDir"
Value="c:\Orbiter2016\orbiter"
PerformEnvironmentSet="true"
/>
</VisualStudioPropertySheet>
i found 2 of these:
<?xml version="1.0" encoding="utf-8"?>
<Project DefaultTargets="Build" ToolsVersion="12.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ImportGroup Label="PropertySheets">
</ImportGroup>
<PropertyGroup Label="UserMacros">
<OrbiterDir>c:\Orbiter2016\orbiter</OrbiterDir>
</PropertyGroup>
<PropertyGroup>
<_ProjectFileVersion>12.0.21005.1</_ProjectFileVersion>
</PropertyGroup>
<ItemDefinitionGroup />
<ItemGroup>
<BuildMacro Include="OrbiterDir">
<Value>$(OrbiterDir)</Value>
<EnvironmentVariable>true</EnvironmentVariable>
</BuildMacro>
</ItemGroup>
</Project>
<?xml version="1.0" encoding="Windows-1252"?>
<VisualStudioPropertySheet
ProjectType="Visual C++"
Version="8.00"
Name="orbiterroot"
>
<UserMacro
Name="OrbiterDir"
Value="c:\Orbiter2016\orbiter"
PerformEnvironmentSet="true"
/>
</VisualStudioPropertySheet>