On Friday, November 24, 2017 at 10:44:35 AM UTC-8, wrote:
I need to do a short test run on my ventus 2cxm engine. The fuselage is on its cobra dolley in my garage, and I can wheel it into my driveway and tie the tail to a post. I'm nervous about this, in case there is some pitfall I haven't considered. Has anyone done an engine test run like this?

Congratulations you are already part of the way there by posting about doing this online. You know this is not a good idea, asking for advice to try to make it a slightly less bad idea is not good. But if you do it please make sure you have somebody video this who is able to post the video of any accident on YouTube.

I've done and seen a lots of ground runs. Either in a professional built heavy duty steel engine stand (Williams Soaring) or with rigging the damn glider. If the later, tie the tail down to a heavy object like a pickup truck with nylon tow straps. Don't dick around with damaging expensive toys or risking people's lives.

I've also seen the aftermath of people walking into light aircraft propellors, which makes me awfully nervous about doing stuff like this.