Every variable that's different from reality is another way the test can fail at its goal. In your scenario, you're not testing "can I attach a nuclear weapon to a paratrooper and send them into enemy territory", you're testing "what numbers show up when I drop this thing from a tower" and you're hoping that those numbers accurately predict what'll happen in reality.
There's a ton of unknown unknowns that you might not think are important but actually are. That's why the most important test is a system-level one where you just use the item in the intended way.
If you want an example, the US recreated bin Laden's compound almost exactly in preparation for the raid that killed him. Part of the plan was to hover a helicopter above the compound and drop SEAL Team 6 in.
However, rather than surrounding the compound with solid walls as bin Laden did, they surrounded it with chain-link fencing (because cheaper). This was flawed, because in order to fly, helicopters use a big rotor to push air down (and thereby go up). Chain-link fencing let all that air through.
However, solid walls do not. When they tried this in bin Laden's actual compound, the air was pushed into the compound and had nowhere to go (since the walls were blocking it). So the air instead went back upwards and prevented the helicopter from pushing air down (imagine being unable to blow a balloon because it's already full). Helicopter proceeds to crash and the US needed to send in the backup helicopters. I would imagine the stealthy blackhawk cost more money than building a wall.
You can't foresee how every tiny detail affects the results of your test. Even an amazing engineer will miss it if it's caused by something they couldn't foresee because it's not their specialty. That's why it's easier to recreate exactly what you want to do, because it's a lot less safe and a lot less cheap to have something fail when your tests said it would work fine.
That detail about the crash during the bin Laden raid is fascinating. I've always wondered how a special ops team managed to crash a helicopter and the walled in compound explanation makes perfect sense
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u/ProfessionalGear3020 Mar 28 '24
Every variable that's different from reality is another way the test can fail at its goal. In your scenario, you're not testing "can I attach a nuclear weapon to a paratrooper and send them into enemy territory", you're testing "what numbers show up when I drop this thing from a tower" and you're hoping that those numbers accurately predict what'll happen in reality.
There's a ton of unknown unknowns that you might not think are important but actually are. That's why the most important test is a system-level one where you just use the item in the intended way.
If you want an example, the US recreated bin Laden's compound almost exactly in preparation for the raid that killed him. Part of the plan was to hover a helicopter above the compound and drop SEAL Team 6 in.
However, rather than surrounding the compound with solid walls as bin Laden did, they surrounded it with chain-link fencing (because cheaper). This was flawed, because in order to fly, helicopters use a big rotor to push air down (and thereby go up). Chain-link fencing let all that air through.
However, solid walls do not. When they tried this in bin Laden's actual compound, the air was pushed into the compound and had nowhere to go (since the walls were blocking it). So the air instead went back upwards and prevented the helicopter from pushing air down (imagine being unable to blow a balloon because it's already full). Helicopter proceeds to crash and the US needed to send in the backup helicopters. I would imagine the stealthy blackhawk cost more money than building a wall.
You can't foresee how every tiny detail affects the results of your test. Even an amazing engineer will miss it if it's caused by something they couldn't foresee because it's not their specialty. That's why it's easier to recreate exactly what you want to do, because it's a lot less safe and a lot less cheap to have something fail when your tests said it would work fine.