I am scribing a 1/72 He 111 bomber. I was wondering how deep would you make a grove for panel lines to make them look realistic on the fuselage and wings?
I’m one of those who believes panel lines should be barely perceptible. The depth of groove should be so slight that it would be impossible to state in any sort of practical unit of measure. Look at photos of actual He-111s and ask yourself how deep you’d have to go to replicate what you see. Panel lines in my opinion tend to get overdone a lot - but to each their own - I would just score as lightly as possible.
I agree strongly with Bearcat. There are a number of things we do on small scale models that almost never can be truly to scale (antenna wire is another). One idea is to observe closely real aircraft at an airport or air base. If that is impractical, do a google image search of similar planes and look at a number of plane images.
Now, there are two ways to look at it. Doing the process as you THINK a real aircraft should look, or doing it as it really looks. Our minds play tricks on us and often emphasizes certain detail after we look at something. This is the reason some folks do overemphasize some details. You know the lines are there if you look closely, so you feel they should be visible at a distance.
The concept of scale distance is valid here. We generally view a model from about two or three feet. So viewing a 1:72 scale model is equivalent to viewing the real plane from about 140 to 220 feet away. The smaller the scale, the further the scale viewing distance is. Keeping this in mind may help answer the question.
Also, it depends on the type of finish. Bare metal airplanes show the panel lines more than painted aircraft do- the paint tends to fill in the lines except for panels that are removable for servicing.