JAAlbert From United States of America, joined Jan 2006, 1661 posts, RR: 1
Reply 14, posted (8 years 1 month 3 weeks 6 days 2 hours ago) and read 16237 times:
It looked like the building shook when that blade came off. Is that due to the explosive charge or was that actually due to the energy released when the blade came off? I would be very, very concerned if I heard an explosion like that -- and the plane shook -- like that building did while over the middle of the atlantic.
GEnxPower From United States of America, joined Apr 2005, 121 posts, RR: 0
Reply 18, posted (8 years 1 month 3 weeks 5 days 22 hours ago) and read 14585 times:
Quoting JAAlbert (Reply 14): It looked like the building shook when that blade came off. Is that due to the explosive charge or was that actually due to the energy released when the blade came off? I would be very, very concerned if I heard an explosion like that -- and the plane shook -- like that building did while over the middle of the atlantic.
Not to take away anything from the energy released from such a fan blade out event, the video does use certain amount of artistic license and dramatization of the event, especially the shaking of the camera at the monitoring station. The engine will get a tremendous shake for sure, but feeling the building shake like that is just director's extra little touch.
In the plane, you will probably feel a jolt but that's the entire point of the FBO, to keep the blade out event under control. Other parts of FAA certification requirement include containment, vibration response, load imbalance from non uniform fan and engine control. (i.e Pilot or control must still have enough authority over the engine power to at least shut it down safely without the engine going out of control)
The explosion and the flames are real though, and so is the shaking, vibrations and swelling of the fan case and fan cowl. Remember, the test cameras used for such a test are special high frame rate cameras, that captures up to 10,000 frames per second. Normal 30 fps camera won't pick up much vibs and deformations at all.
TepidHalibut From Iceland, joined Dec 2004, 211 posts, RR: 6
Reply 19, posted (8 years 1 month 3 weeks 5 days 22 hours ago) and read 14541 times:
Quoting YUL777 (Reply 9): Can somedy tell me if this test will also certify the engine concerning the brid strike issue of if it's a whole different test?
Nope. The Fan Blade Off and Bird Ingestion tests are completely different.
- FBO - Gotta contain all high energy debris. Obviously, the engine is not expected to continue producing thrust.
- Medium Bird Ingestion - (The usual test you see video of). The engine needs to cope with approx 8 medium sized birds hitting it at take-off speeds, and still be able to produce 75% of rated thrusts. The reasoning is that medioum sized birds are flocking birds, so could affect all of the installed engines. You don't want to lose all thrust.
There is some overlap and wrinkles regarding Large Birds and LFBs, but I'm trying not to get too technical.
Yul777 From Canada, joined Mar 2007, 12 posts, RR: 0
Reply 20, posted (8 years 1 month 3 weeks 5 days 22 hours ago) and read 14322 times:
Thanks TepidHalibut for the explanation. I was discussing about this test this morning with a few colleagues and I was told by a former Boeing engineer that they don't use frozen chicken no more to simulate the bird ingestion. They use something like an hard ball, maybe the size of a handball, that is thrown in the engine for this particular test. Can anyone confirm the information and give more detail about this ''ball''.
Airfoilsguy From , joined Dec 1969, posts, RR:
Reply 22, posted (8 years 1 month 3 weeks 5 days 21 hours ago) and read 14201 times:
Quoting Yul777 (Reply 20): They use something like an hard ball, maybe the size of a handball, that is thrown in the engine for this particular test.
Last I heard they still use real birds. Not frozen ones because your chance of encountering a frozen bird in flight is almost nil. The same can be said for handballs. When testing engines the conditions have to be realistic. I don't think a handball would be realistic enough.