Navigadget Mk I ?

[2banaviator]

I've come across a mechanical flight calculator that I've not seen before, and thought I'd put it up to the community to ponder.

The device is labeled Navigadget Mark I and appears to be a speed and course correction computer. On the back is handwritten "WWII 8th Air Force B-17... etc." but I have my doubts. The former owner (now deceased) believed it to be used to course-correct during bomb runs. If this were an officially-sanctioned flight computer, I would expect it to have typical USAAF or RAF markings. I've attached some photos. Any clues?

 

[bdefen]

Lots of inputs. You'd sure have to be fast with it to use it during a bomb run.....maybe the navigator would help out?

 

[2banaviator]

Lots of inputs. You'd sure have to be fast with it to use it during a bomb run.....maybe the navigator would help out?

It appears that the device was intended to be placed upon a map/chart with a scale 1.25in=10mile along the planned flight path. I've determined that the left side scale is actually Miles, not MPH. The center axis at about 40 Miles is the calculated ground speed, up to 150 MPH. You can't see the 150MPH marking in these photos, only showing up to 90MPH. So, fairly slow.

That semi-circle is marked in minutes. If I put its first "0" on the angled line marked "Start" which leads to the "0" on the Miles scale, and slide that semi-circle edge over to 60MPH, any angled line from the Miles scale lines up with the number of minutes it will take to reach that mile total traveling at 60 MPH. At the 60 Mile mark, the angled line to the semi-circle lands at the second "0", i.e., 1 hour later.

So, yes, lots of inputs but thankfully this was for a slow aircraft and was likely to be used by a navigator/observer.

Still trying to pin down its history..... I'm guessing 1930-vintage.... Any other thoughts?