The last sentence of the last post is my major concern. I am having trouble imagining getting in a brand new airplane that has never even been taxied and blasting off for several hours at full power. What about brake testing? Checking control surfaces in the air, etc.? I am interested in how others have tackled this challenge.
If you are using Lycoming cylinders I'd follow their instructions. In this case SI 1427C is the latest guidance on break in. In it they advocate a 15 minute ground run. They say you can do it on the plane with your flight prop as long as temps stay in limits. Subsequent they call for a normal take off, normal power climb (25 square?), and then cruise at 75% for an hour and then vary between 65 and 75% for the next hour. Then land and check it over.
So you aren't wide open for hours on end. It's pretty much normal cruise flight. (You get bored circling the airport after about 15 minutes.) If you have a CHT gauge, and you really, REALLY, should have a CHT gauge, you'll probably see your CHT's come down significantly after about 30-45 minutes. That's the rings seating. In most engines nowadays it happens quick.
As for the first flight of the plane and engine at the same time, with 10,000 RV's flying I'm sure a few thousand people have down this. EAA is also developing some serious flight test resources. Plan, plan, plan. Then practice, practice, practice. When we flight test at work (I work for an OEM), we try to think of every possible scenario and then have a plan for that. We premake flight test cards with info we want. We have people on the ground overseeing everything and directing the test. The goal is to make all the decisions ahead of time and turn the pilot into a meat servo.
You can brake test with a garden tractor and a tow bar. If a wing is heavy, suck it up for 2 hours. If the flaps won't come down it doesn't matter if you do a no flap landing after 15 minutes or 2 hours. And if you get an oil leak after ten minutes, land. It's not the end of the world As long as you don't over temp the CHT the worst that will happen is you'll glaze the cylinders, which is inconvenient but not hard to rectify.
DEM