c5load From United States of America, joined Sep 2008, 917 posts, RR: 0 Posted (3 years 1 week 3 days 10 hours ago) and read 9337 times:
What is the difference between these two engines and the lack of the "cone" on the one at the right? What is the purpose of the "cone" (it's not called that, but I don't know the name)?
MQTmxguy From United States of America, joined Nov 2007, 196 posts, RR: 0 Reply 1, posted (3 years 1 week 3 days 8 hours ago) and read 9245 times:
They both have a cone, the one on the right's is just inside the exhaust duct.
The exhaust cone acts as an aerodynamic cover for the tubine hub/shaft and is part of the convergent duct geometry at the very aft of the exhaust that converts the high pressure gas coming off the last turbine stage into high velocity gas as it exits the engine (creating more thrust).
In a mixed stream exhaust it (along with an exhaust gas mixer) mixes the by-pass and core exhaust.
Well at least we can all take comfort in the fact that NW will never retire their DC-9s
AirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 26 Reply 2, posted (3 years 1 week 3 days 7 hours ago) and read 9122 times:
That cone is, what we A&P's call it, is the CNA duct. CNA = Common Nozzle Area Duct.
A Safe Flight Begins With Quality Maintenance On The Ground.
boeing767mech From United States of America, joined Dec 2000, 992 posts, RR: 3 Reply 3, posted (3 years 1 week 3 days 5 hours ago) and read 9020 times:
Quoting c5load (Thread starter): What is the purpose of the "cone" (it's not called that, but I don't know the name)?
The cone is a fairing used to smooth airstream coming out of the turbine assy, as it goings around the Aft bearing assy. The Pratts on the MD-11 have the cone assy, but it is inside the exhaust sleave area, You can see it if you look inside the tail pipe. Interesting thing is the CF-6-80's on the 767,A300 and MD-100 all have differnet exhaust cones depending on the dash number of the engine.
Aeroflot001 From Argentina, joined Oct 2009, 384 posts, RR: 0 Reply 6, posted (3 years 4 days 21 hours ago) and read 7546 times:
Does the 757 with RB211 engines or the Airbus A318,19,20,21 have it as well. On the engines that these aircraft have it seems as though the entire back of the engine was sliced off.
I (among others) have a photo album dedicated to engines. Most of them have cones, some rounded and some with a spike. They look different but have the same purpose.
Minor correction (for the engines I know about): CNA - Common Nozzle Assembly, tho' I know some learned folk think of it as the Cold Nozzle Assembly.
Common Nozzle basically because the same structure often contains the cold nozzle and the hot nozzle structures. Both nozzles have important thermodynamic roles, influencing pressure balances across fan and core systems, so it's not surprising that people crowbar Area into the name.
Also : can be known as the INA on some engines - Integrated Nozzle Assy.
Confusing, but I guess that's why they need geniuses in the business. ;o)
Pacific From Hong Kong, joined Mar 2000, 1032 posts, RR: 0 Reply 11, posted (3 years 1 day 11 hours ago) and read 6818 times:
I'd like to ask an additional question. How much fuel burn penalty (and any other negative effects) would you have when you fly without the cone? I can vaguely recall a Delta 777 losing a cone in the early stages of a longhaul flight, but made it to the destination safely, the crew understandably unaware of the fact it had detached. That cone smashed down into a residential area.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 12, posted (3 years 1 day 9 hours ago) and read 6774 times:
Quoting Pacific (Reply 11): How much fuel burn penalty (and any other negative effects) would you have when you fly without the cone?
I'm no not sure that's been calculated, since it's not on the CDL. It could be significant though...if you're missing one blocker door you loose over 1000 lbs from MTOW on a 777 (the exact number depends on the model), and a missing exhaust plug would be much worse, I suspect.
cobra27 From Slovenia, joined May 2001, 978 posts, RR: 0 Reply 13, posted (3 years 1 day 6 hours ago) and read 6693 times:
I saw today an Rollse royce BR710 engine on Gulfstream. Form behing it looked it had a half open cone. Maybe it had a full cone inside and that was just a back of the engine?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 15, posted (3 years 1 day 3 hours ago) and read 6628 times:
Quoting A342 (Reply 14): What's a blocker door, if I may ask?
In a translating-sleeve (aka cascade) thrust reverser, when the sleeve slides back the blocker doors swing out from the wall of the fan duct and block the fan flow out the back, forcing fan air to go out through the cascade vanes in the sides of the nacelle. There are usually 10-14 blocker doors per engine. All modern Boeing's use this style of reverser...Airbus is more fond of the petal-style.
A342 From Germany, joined Jul 2005, 4655 posts, RR: 4 Reply 17, posted (3 years 5 hours ago) and read 6411 times:
Quoting tdscanuck (Reply 15): There are usually 10-14 blocker doors per engine. All modern Boeing's use this style of reverser...Airbus is more fond of the petal-style.
Quoting AirframeAS (Reply 16): They are on CFM's mostly. Look at F9's Airbuses, those are blocker doors, 4 of them. Two on each side.
I thought the CFM56-5 series engines (powering the A32S family plus A342/343) use a petal style reverser. So now what's the correct designation for the reverser in this pic:
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 19, posted (3 years 1 hour ago) and read 6329 times:
Quoting A342 (Reply 17): I thought the CFM56-5 series engines (powering the A32S family plus A342/343) use a petal style reverser.
They do. The choice of reverser type is an airframer thing, not an engine thing (except in a few wierd RR cases where they have the entire engine/nacelle package).
Quoting A342 (Reply 17): So now what's the correct designation for the reverser in this pic:
Those are petal reversers.
Quoting AirframeAS (Reply 16): These are not exactly cascading on the F9 aircraft. Close, but it isn't.
They're not cascade reversers at all. They're petal reversers.
Quoting AirframeAS (Reply 18):
Blocker doors. It says that on a warning decal on those doors, at least on the F9 powerplants.
Nomenclature problem here that I didn't know about until now...both petal and cascade reversers have blocker doors, but they're not the same part in the two different reverser types. For what are hopefully obvious reasons, you can't be missing a blocker door on a petal reverser; you can on a cascade reverser.
B727LVR From United States of America, joined Jul 2008, 628 posts, RR: 0 Reply 20, posted (2 years 12 months 4 days 19 hours ago) and read 6283 times:
Quoting 7673mech (Reply 5): In 20 years I have never heard it called that. We A&P's always call it a tail cone.
Some of us DC-9 mechs might disagree there. Our tail cone is a bit different, and much larger...
I have usually heard it called the exhaust cone.
Quoting c5load (Thread starter): What is the difference between these two engines and the lack of the "cone" on the one at the right?
The main difference in the engines you show are: The one on the left is a CF-6 and the one on the right is a PW4060. MQTmxguy gave a pretty good example. Different manufacturers, different designs thats all.
I'm like a kid in a candy store when it comes to planes!
AirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 26 Reply 21, posted (2 years 12 months 2 days 18 hours ago) and read 6029 times:
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 22, posted (2 years 12 months 1 day 21 hours ago) and read 5887 times:
Quoting AirframeAS (Reply 21): No, they are not, but the logic is the same, and the actuator works the same pushing the doors in the same direction.
In a cascade reverser, there's no connection between the actuator and the blocker doors. The actuators push the translating sleeve...passive linkages between the blocker doors and the inner wall deploy the blocker doors when the translating sleeve moves back. On a petal reverser, the actuator actually moves the blocker doors directly.
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