SCAT15F From United States of America, joined Feb 2007, 402 posts, RR: 0 Posted (10 months 3 days 5 hours ago) and read 2453 times:
I was noticing how for the GEnx-2b67, Boeing installed thrust (Boeing equivalent thrust?) is 66,500 lbs. GE rates the engine at 67,400 lbs.
Obviously, installed thrust is going to be less than for a bench test engine, BUT, how come Boeing installed/equivalent thrust for the CF6-80c2b8f on the 764 is 63,500 lbs and GE says it is only 62,100 lbs?
And for the PW4062 Boeing equivalent/installed thrust is 63,300 vs Pratt's info stating 62,000 lbs?
Makes me wonder if the GEnx nacelle chevrons actually reduce thrust slightly...
SPREE34 From United States of America, joined Jun 2004, 2158 posts, RR: 10 Reply 1, posted (10 months 3 days 4 hours ago) and read 2435 times:
Don't know about your specific numbers given, but across the engine spectrum, there is a slight thrust loss where chevrons are used. It is small enough to be considered a worthy trade for meeting noise restrictions.
I don't have a link, but recall reading this in AW&ST, and another publication 2 or 3 years ago.
I don't understand everything I don't know about this.
LH707330 From United States of America, joined Jun 2012, 431 posts, RR: 0 Reply 2, posted (10 months 2 days 21 hours ago) and read 2262 times:
I've heard you lose about .25% from the drag penalty that the chevrons induce, but in exchange, the nacelles can be narrower for the same noise level, so there's a weight tradeoff. The A380's nacelles are oversized so they could make QC .5 approaches, and they paid for that ability in weight. The two approaches likely have their own respective optimal use cases, just as with any other engineering tradeoff.
Well, if I remember correctly, a bench test engine run is usually conducted without the engine nacelle/cowling and in static conditions resulting in optimum airflow and optimum thrust. Installed thrust is typically(?) a little less depending on the nacelle inlet design/restriction.
HAWK21M From India, joined Jan 2001, 31450 posts, RR: 57 Reply 6, posted (9 months 4 weeks 1 day 17 hours ago) and read 1530 times:
Quoting SCAT15F (Reply 5): Well, if I remember correctly, a bench test engine run is usually conducted without the engine nacelle/cowling and in static conditions resulting in optimum airflow and optimum thrust. Installed thrust is typically(?) a little less depending on the nacelle inlet design/restriction.
How would the thrust be affected if the Engine is run on a Stationary stand with not much relative wind.