Timeline for What is the purpose of the fin at the Boeing 787 APU exhaust?
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 16, 2023 at 2:43 | answer | added | 787Engineer | timeline score: 0 | |
| Jan 2, 2018 at 21:22 | answer | added | Mark Jones Jr. | timeline score: 3 | |
| Dec 21, 2017 at 19:17 | comment | added | jwzumwalt | All gas turbines including APU's have a drain tube from the combustion chamber that will drain excess fuel onto the ground. If there was any excess fuel in this APU, the slope of the exhaust would pool it in the engine and that fairing would not have any effect - nobody would stand for that. | |
| Dec 21, 2017 at 10:34 | comment | added | Penguin | Gas turbines don't spit flames out the back when they start up unless something has failed, and a shield on the exhaust wouldn't stop that anyway. | |
| Dec 20, 2017 at 21:48 | comment | added | TomMcW | @jwzumwalt The article mins linked shows it has nothing to do with noise. It's to avoid a flamethrower when they start it up. | |
| Dec 20, 2017 at 11:32 | comment | added | jwzumwalt | It's primary purpose is noise abatement. NASA has been encouraging mfg to install similar shielding plates near other parts of the aircraft such as the whistling wheel brake parts. The flying wing concept has the engines above the fuselage (for ground noise blocking) for the same reason. During landing, the airframe is louder than the engines. NASA has several high profile noise abatement research projects such as QAT. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130013127.pdf and nasa.gov/centers/langley/pdf/70882main_FS-2002-09-73-LaRC.pdf | |
| Dec 19, 2017 at 12:22 | comment | added | user3528438 | My guess is, because of the shape of the tail, air will be flowing up and meet the horizontal flow. If there is a hole in the middle there will be a lot of turbulence so they added a deflector to let them mix slowly. For a plane of this size this is more likely to reduce noise or improve the efficiency of the APU. | |
| Dec 19, 2017 at 9:41 | comment | added | mins | @Pritam: What about writing an answer? Here is more information you can use (it prevents torching). | |
| Dec 19, 2017 at 8:28 | comment | added | Koyovis | It's a bib for the APU to stay tidy. | |
| Dec 19, 2017 at 5:51 | history | tweeted | twitter.com/StackAviation/status/942995673909284864 | ||
| Dec 19, 2017 at 3:46 | history | edited | Pondlife |
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| Dec 19, 2017 at 2:38 | comment | added | Romeo_4808N | At a guess it’s an aerodynamic fence of some sort, most likely added during flight test as a band aid against unwanted turbulent airflow in that region. It’s a relatively simple fix for bad aerodynamic design | |
| Dec 19, 2017 at 2:05 | comment | added | Pritam | APU fuel drip shield. | |
| Dec 19, 2017 at 1:56 | history | asked | Chaintawit Singkaew | CC BY-SA 3.0 |