Modelling App

[tigercat]

you'd  think there would be an app for modellers to insert there creations  into a photographic  background  of suitable vintage and with a scaling tool .

Various  airfields etc .

[zenrat]

Yes.  It could use green screen technology - although that could be problematic for military builds with their preponderance of green paint.

[tigercat]

I think they also use blue screen so that could be an option

[Hobbes]

Any photo editing program can do this. I use the free Paint.net (Windows) and shareware GraphicConverter (Mac).
Green/blue screening makes it a bit easier, but that's done by photographing the model on a suitable single-color background. A sheet of colored paper will do.

Process:

1. open a photo of the model on a single-color background.
2. use the Magic Wand tool to select the background.
3. Delete the selection.
4. Invert the selection: you've now selected the model instead of the background. This leaves you with a cut-out photo of the model, ready for insertion into a background.
5. Paste the cutout into a background photo, preferably into a new layer.
6. Drag the selection handles to scale the cutout.