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Questions tagged [nacelle]

Questions about the round enclosures that house engines.

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0answers
38 views

Do open propellers experience pre-entry drag (additive drag) like an engine in nacelle?

Engines in a nacelle experience pre-entry (also called additive) drag. Do unducted propellers experience it too?
5
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1answer
212 views

Why does a subsonic nacelle inlet have a throat before the diverging section?

Aircraft propulsion 2nd edition by SAEED FAROKHI" p.340 Aircraft propulsion 2nd edition by SAEED FAROKHI" p.123 As we can see from the image, the nacelle slightly converges towards a throat, before ...
4
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1answer
321 views

What is that extended nacelle feature on the Honda HA-420 HondaJet?

Here is a picture of the Honda HA-420 HondaJet with strange extended engine housings. Why are they required? What are they for? I am not asking about the red covers, but the white engine housing ...
14
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5answers
6k views

Why does the B-52 outboard engine nacelle have a sharp change in shape?

The outboard engine nacelle of a B-52 appears to have a change of shape too extreme for just blending to the center-line of the engine pod. Why is the B-52 outboard engine nacelle shaped the way it is?...
6
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3answers
1k views

Is it practical to integrate turbofan or ramjet engines into an airliner wing?

The de Havilland Comet had turbojet engines integrated into its wings, such that its nacelles were mostly flush with the wings like so: (wikimedia.org) I recognize that turbofan engines are ...
19
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2answers
1k views

How do turbofan nacelle lengths compare?

For example, compare the JT9D and the PW4000 below (both from Pratt & Whitney, both on a 747): (Left, Right) The PW4000 has a longer forward nacelle, and a covered exhaust cone. On the inside—...
2
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0answers
98 views

What are the current principles for turbofan nacelle air path design?

The Wikipedia entry for 'turbofan' states: Some high bypass ratio civil turbofans use an extremely low area ratio (less than 1.01), convergent-divergent, nozzle on the bypass... But the article ...
7
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1answer
1k views

How does inlet spillage drag produce a lip suction effect?

From this page: Spillage drag, as the name implies, occurs when an inlet "spills" air around the outside instead of conducting the air to the compressor face. The amount of air that goes through ...
11
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1answer
5k views

Why do Boeing aircraft have serrated engine nacelles, but Airbus does not?

Why do Boeing's new generation of jets (787, 747-8, 777X, 737MAX) have serrated engine nacelles whilst Airbus' latest (A350, A320neo etc) do not? I understand that Boeing's nacelles reduce turbulence ...
6
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1answer
265 views

Does the stream of engine thrust act as a good drag shield against the nacelle?

Taking a look at the typical large engine of a commercial plane, it looks rather unstreamligned. Nacelle drag is significant IIRC. However, then I suddenly remembered these engines produce a large ...
6
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2answers
630 views

What is the purpose of the translucent tube and dial on JU 52 engine nacelle?

Mounted on top of each JU 52 engine is a translucent tube and a dial (see images). What is the purpose of the tube and what does it measure? Does the dial measure (oil or fuel) flow or quantity? Are ...
25
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3answers
2k views

Why are turbofan inlets leaned/angled forward?

(Image Source: Wikipedia) Seeing that everything is radially symmetric (apart from the nacelle mount, naturally), I wonder why the inlet (the front part of the nacelle) is usually skewed?
61
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4answers
56k views

Why does the Boeing 787 engine nacelle exhaust have such an unusual shape?

Why does the Boeing 787 nacelle have this unique shape at the exhaust: I haven't seen it on any other airplanes, does it serve an aerodynamic purpose or help engine efficiency or is it just to look ...
14
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3answers
2k views

Do nacelles around aircraft engines help in reducing the engine sound?

I know that the nacelles around the aircraft engines are actually a housing and are generally lightweight and have may components like inlet cowl, fan cowl, etc., but do they help in reducing the ...
47
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3answers
36k views

Why are the Boeing 737 nacelles odd shaped?

Why is a Boeing 737 NG engine not completely round in shape? It seems to be flat at the bottom and round at the top and sides. Earlier Boeing 737 versions (100 and 200) seem to have a more rounded ...
43
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2answers
24k views

What is this flange on the engine?

Flying home from the Denver ComiCon, on a 737, I saw an angled flange on the engine. Could you describe its purpose? Photos by CGCampbell licensed CC0