attitude during normal flight

[husqvarna]

I notice in this picture, http://www.airliners.net/open.file/425270/M/, that the engines appear to be parallel with the ground whilst the nose is pointed slightly down. During normal cruise, are the engines still parallel with the ground, or do they point upwards slightly so that the fuselage of the plan is parallel with the ground? Or maybe neither.
Thanks for your answers.

[andyb79]

with my extremly limited knowledge(i really am expecting to get shot down for this!!!) but in the picture with the aircraft "parallel with the ground" you would expect the engines to point down because when you take into account the angle of Incidence and the fact it will always fly with a positive angle of attack should mean during normal straight and level flight they will sit pretty straight with the relative airflow

i wonder how long till someone "corrects" me on this!

[OBK!]

Almost all aircraft have a nose up attitude in the cruise, unless they're doing mach 2 unintentionally...

The nose is pointing downwards on the ground because if it wasn't, then you'd have the aircraft sitting on it's derier (fr sp?) because of the bloody big engines at the back...

The engines are parallel with the ground because...I dunno. You need a Learjet person or a side view to tell.

[Notso Fantastic]

The airflow aft of the wing has a downward vector after flowing over the wing, so the engines are angled downward in relation to the fuselage- you want to pour that exhaust parallel to the airflow for max efficiency. Coupled with a positive fuselage angle of attack in cruise, the engines can be pointing significantly upwards. Cowlings are not even all the way around- engine accessories are hung underneath the engine so the cowlings are usually larger underneath, so viwed from headon, you can get a misleading impression of the engine angle. Because of upswept fuselage design at the rear (to avoid ground contact on take off and landing), the most efficient cruise angle to minimise fuselage drag (Form drag?) is usually a couple of degrees nose up.
Sorry Andyb- you got that arse about face! And OBK, that doesn't make sense. It is all a question of balance- you could hang the engines off the back of the fuselage- you would need the wing and wheels to be well back. Pointing nose down on the ground doesn't stop it tipping over!

[DBate]

It's 'derrière'. ;)

[Onan the Clumsy]

Notso, thanks for the answer, I have often wondered this and noticed quite an uphill hike on transatlantic flights when walking for'ad.

I'd noticed the engines were all pointed upwards too and couldn't figure it out, though your answer makes sense - just like the pitot tubes on the front of a 737 don't point forward I suppose.

[calypso]

Longhaul flight climb in steps as they burn fuel and get lighter. You might have timed your wlk with a cimb segment.

Just a thought

[Notso Fantastic]

All jets that I know cruise at about 2 to 2 1/2 degrees body angle nose up at standard cruise speed to minimise fuselage drag. Sometimes when we are trying to waste time so as to not arrive too early (creates parking problems at base), this can go up to 3 degrees when flying at M.78 instead of M.86 fast cruise). An intermediate climb might make all of 1/4-1/2 degree difference to that (at 500mph it doesn't take much!).