What was he/she doing? No radio,

Went out to the airport this morning about 1:00 am to top off my tanks,
there was an aircraft on the runway it looked like super cub or something
with big tires practicing either high-speed taxiing on the runway or
simulated engine outs and bouncing? I turned on my scanner to find out what
he was doing but there was no radio comm's. I sat in the car and watched
about 10 of these high speed runs he/she seemed to only get the main about
10-50' off the ground hold for a bit then idle to full stop at the end of
the runway then he would taxi back to 08 and do it again. 11th or 12 time
he/she departed and was gone.

Any logic or ideas what he/she was doing this for??? was a dam nice looking
& sounding aircraft you could here the changes in his/her CS prop during
his/her run-up each time he did his runs down the runway and sounded like it
had a large engine.

I am thinking maby he/she was doing some aircraft testing but at 1 Am in the
morning??