...to me, the sound of a healthy engine, almost any engine, is as good as the finest of symphonies.
And a in any live performance, some if it is felt rather than heard. That doesn't connect until you try to record it.
It is a dual pattern condenser USB
Whose make and model is?
Omni because of the better low frequency response.
Omni or whatever is natural for your microphone is always going to sound better than any of the manufactured patterns. Cardioid patterns have two ratings, what does it sound like straight on and what does it sound like from the back. Everything's a balancing act. If you're doing all this outside, then you don't have to worry so much about echoes. Stay away from large buildings.
Then there is the matter of positioning the mic.
Plug good quality headphones in your computer and listen while you wave the microphones around (Edit > Preferences > Recording > Playthrough). You may have troubles not obvious. Microphones pick up reflections from the ground. Just starting the microphone on the ground and slowing lifting it up can be a revelation. When you see recordings in a studio, the microphone is generally three times closer to the performer than any large flat surface. Drums can mess that up, but those can be tuned so they sound good, not necessarily accurate. This is one place where directional microphones can be valuable.
it would be ideal if I could record in stereo
I wouldn't do it any other way. If you were on a Mac, there are ways to record two USB microphones, On a PC, you have the option of using two computers and two USB microphones. They don't have to be identical, but that's best.
Go out at the beginning and yell "MARKER" and clap your hands. You can use the hand clap to match up the two recordings later, one left and one right.
See what you talked yourself into?
Koz