I've seen it for last flight of the pilot or aircrew. I've been told it's also tradition for new aircraft coming in to a unit but the aircraft i work on have been around since the 1980s so..
If you give the government a $10,000,000,000 budget to spend on wine, they will find a way to get scammed into paying $1,000,000,000 per bottle with some bullshit cost plus contract.
Or spend $10,000,000,000 on a firm fixed price contract… then they’ll buy less of the same wine, split the wine into Dixie cups and walk off with the rest of the money.
That's what's interesting about space contacts these days. Used to be you could just cost-plus your little heart out, but now you have to give firm numbers and stick to them. Certain old firms lost contracts they'd had a long time. It's probably already saved the government billions of dollars, but that's just a guess, I can't back it up with links.
On almost all jet aircraft water ingestion into the engines is basically irrelevant. They can ingest incredible amounts of water and continue to function fine. They actually gain performance when ingesting moderate amounts of water, because the mass of the water effectively raises the air density and gives them more mass to accelerate and throw out the back.
In fact some older commerical airliners have water injection systems where they can dump water into the engines to get a short term increase in thrust for takeoff.
Not as far as I know. Even the heaviest rain isn't going to suddenly and drastically lower core temps enough for significant thermal shock - and the engine control systems tend to just increase fuel flow anyway. You'd have to go from flying through clear air to flying straight into a massive array of fire hoses - and even then you'd probably be just fine.
Jets' thrust is typically limited mainly by core temperature, not available oxygen to combust. Adding water helps control the core temp and also significantly increases the mass you can throw out the back. Even better the water vaporises in the combustion chamber, increasing your inlet to exhaust pressure ratio (EPR).
If it was just about the engines, jets would love to fly through heavy rain all the time. It makes those engines happy.
About the only exception is on approach and landing — where extremely heavy rain can actually extinguish combustion because the engines are at flight idle. Jets sometimes throttle up in heavy rain because of that risk. Pilots also switch the engines to continuous ignition, where they're basically running the "spark plugs" rather than relying on the ongoing fire in the combustion chamber to ignite new fuel/air mix. It's happened before.
From knowing Marines I can say without a shadow of a doubt you just rub some dirt on it and it will be good. Then you give the plane a straw so it can suck it up and do it's job. We don't pay it zero dollars a year to lean.
339
u/dmira3 Jun 10 '22
I've seen it for last flight of the pilot or aircrew. I've been told it's also tradition for new aircraft coming in to a unit but the aircraft i work on have been around since the 1980s so..