Hi Bpti,
>if that is a real instrument, how come nobody has produced it since?
Conservative thinking? :-)
"If it was good enough for Lindbergh, it's good enough for me!"
The Americans took instrument fusion another step further at the end of WW2 and also integrated the compass in the same device.
If I remember the description correctly, you'd look at a small aircraft model in a three-dimensional instrument, with a green/blue horizon graduated with course numbers.
I think it was called "Hoover horizon" after its inventor, a test pilot who unfortunately died in an accident before he could get his invention into production.
Too bad I can't find that article again, or I would have been able to supply some more accurate information.
Regards,
Henning (HoHun)