Simple chirp (swept frequency) generator

Here's a proposed simple generator for a swept frequency square wave (as yet unbuilt).

According to LTspice it is not fussy over component values provided the time constants R1C1 and R2C2 are different.
The only uses I can presently think of for it are as a test signal generator, e.g. for determining a filter or amplifier response, or in a chirp sonar application. Any other uses you guys 'n gals can think of?

Initial conditions on Vcap also affect the response.

In this case equal RC values but mismatched Vcap 2.2 on upper and 2.5V on lower with a drop in frequency from initial oscillations

Neat effect but sensitive to voltage threshold or supply changes

Neat little circuit. I like things like this.
Can't think of any immediate uses for it though.