Building an airplane is not supposed to be an easy undertaking. Building it alone in your oversized garage is a sure sign you've lost your mind. At least it's not a rocket. And the garage is technically an industrial hall near the airport, which makes this a professional operation. Mostly for tax reasons.
Behind the garage, there's a large fenced yard. Between two solid concrete blocks, fixed on a newly welded frame of sturdy steel beams, rests a turbojet engine. It's not pretty, with pipes routed seemingly at random and cables ziptied to the frame. But it doesn't have to be. It just has to work. Apricot walks around the prototype, systematically going through a checklist for fuel valves.
Fifty meters away, there's a tanker trailer full of Jet A-1 kerosene. It's been there for only a few days, and was surprisingly cheap, only about 50k for the fuel and twice as much for the tanker itself. He doesn't even have the permits to drive with one yet, so it's a bit closer to the engine than comfortable.
A fuel line runs from the tanker to a small header tank beside the engine. That must be disconnected before the test begins, so in case anything goes wrong, only a small part of the fuel has a chance to burn. There's no fire department present, surprisingly the law didn't require it. Probably because no one's been mad enough to try this before. What he does have is a decommissioned fire engine with a turret on top and full of F3/SFFF foam solution. The control panels for the turbojet test are set up beside it. If anything does go wrong, he'll just cut the fuel and then operate the turret himself. It's a hot summer day and spreading some water mist around would be nice, but he doesn't want to risk the control equipment; some of it is for indoor use only.
Would it have been smarter to hire professionals for safety? Yes. But doing this in secret will be cool, and that's what matters way more. He dons some PPE and disconnects the fuel line. Nasty, poisonous stuff, that.
When the engine checklist is completed, Apricot takes out the final checklist: perimeter security. He locks all gates leading to the yard, making sure that each of them also bears a sign explaining that an engine test is ongoing and it's very dangerous to enter. There's nothing but the blast deflector behind the engine, and the front is clear too.
And then the final round is done and it's time to do the actual test. He's been building this engine since February, no reason to rush it now. Apricot swaps his shirt for a clean one, not that it helps much when already dripping sweat. He'll be standing behind the fire engine body and observing from cameras only, as tempting as looking at it would be. Two meters of water tank should be enough to stop any flying objects short of the engine itself. A 1 kg blade at 400 m/s has only 80 kJ of kinetic energy and 0.9 m of water should stop that cleanly.
Apricot puts on earplugs and a headset, then powers up the air start system. The blades start turning. He waits half a minute for the spool to come up, then starts ignition and fuel injection. Several warnings show up on screens but none are audible; this is rather normal. He advances the throttle, slowly, up to 12,000 RPM, and checks the screens. Thrust: 21.2 kN, EGT: 680.5 °C. Looking good and right on the curve from simulations. He pushes it a bit more; the testing goal is 28 kN. With a loud crack, the engine frame gives up on one side, smashing the engine into the concrete block on the far side. Instinctively Apricot slams the panic stop button and suppresses the instinct to drop to the ground; the water tank is the actual protection here.
The engine shatters on impact. A sector of the compressor disc avoids the concrete blocks, hitting the fire engine. A 28 kg compressor disc sector at 260 m/s shatters it entirely, and Apricot with it.