WEP how far can they go before they blow

[alcanallen]

Found a very interesting discussion here,When the 5 minutes are up does the engine blow or does it revert back to normal operation?
Chris Fahey No. It keeps going. Goebel below did it for 12 or more. How long until the engine gives up? I don’t know? He made it. They are pretty tough engines, but that does seriously reduce engine life. If all the temperatures remain ok it should run for some time. But you won’t get 50-100 hours out of it... The Army would pull and overhaul if you exceeded limits to make sure you had a safe engine next time...
Chris Fahey I’d have to look up in the maintenance manual. The Merlin was good in 5 min increments or less, up to 30 minutes total if I remember right. But if you exceeded a 5 minute limit they overhauled it right there.

So the question can we edit our Merlins and other`s in CFS3.
alcanallen.

 

[gecko]

Speaking as an aircraft mechanic, there is nothing magic about the time limits imposed on different power settings, such as the 5 minute WEP limitation called out for most Merlins. If you exceed the 5 minute limitation the engine will not automatically be damaged or destroyed by running at emergency power for 5 minutes and 1 second. For practical purposes, the engine doesn't mind being run at emergency power - it's made to be able to do that. However, as mentioned in some of your quotes, it does matter in terms of overall engine life. If you were to always run the engine at WEP, you will dramatically reduce it's lifetime. Problems typically won't manifest themselves immediately, but over the course of hours of flying and multiple flights the engine gets tired, and gradually produces less power, little problems start to creep in as the engine ages, etc. Or perhaps the pilot really abuses the engine on a flight, and gets away with it without seeing any symptoms of problems with the engine. However, the abuse may have caused hidden damage that might manifest itself in spectacular fashion on a later flight.

Exceeding the published limitations of an engine (including time limits, but also RPM, manifold pressure, and various temperature limits) is usually cause for a special inspection to check for possible damage, and likely as not will show no damage, depending on how badly the engine had been treated.

The other thing that can cause issues is how the pilot handles the engine. Large sudden movements of the throttle or propeller control, or running the engine in a way that causes it to heat up and/or cool down rapidly (even if the limitations are not exceeded) will certainly reduce engine lifetime and cause damage that will appear on subsequent flights.

Except for more extreme cases, the limitations mentioned above are primarily related to keeping the engine running reliably over time. In a more immediate sense, the primary thing you're dealing with is temperature. As temperatures increase, the different metals in the engine expand at different rates. This is built into the design, and everything runs best when the engine is running within a certain temperature range. Parts will rub and wear down more quickly when heated up too much, and over time this leads to a less efficient (and thus weaker) engine. If temperatures get even higher, the metal starts to become soft, and this is where you start running the risk of damaging or destroying the engine in a very short amount of time. If you are managing the engine temperatures well, there is little immediate danger of running WEP for longer than allowed - but you are shortening the engine's life by doing so, and your supply officer won't be happy! If you manage temperatures poorly, you can destroy an engine at power settings well below WEP.

There's a lot more to it than what I've explained, but this might give people an idea of how it works on real aircraft, though unfortunately, we can't model this very well in CFS3 - yet.