Ask The Pilot

[Quickstatus]

Why not just straight line the airflow?.

 

[oz_mark]

The 727 is similar. Always thought it was a "win some, lose some" engineering trade-off thing

 

[jpp42]

Why not just straight line the airflow?.

Sharp corners cause all sorts of problems when it comes to airflow. A basic principle of fluid dynamics as it applies to aeronautical engineering, is to maximize laminar airflow - where the fluid travels smoothly or in regular paths, in contrast to turbulent flow, in which the fluid undergoes irregular fluctuations and mixing. This applies to both airflow along the wings/fuselage and in places like engine intakes. If the intake for these tailcone engines were a straight angled line, there might be sharp angles at either end of this intake tube, both where it meets the incoming airflow and where it meets the actual engine itself (down inside the fuselage).

To be clear, I'm not an aeronautical engineer by any means and barely a pilot, but just explaining why curves "make sense" anywhere airflow is involved. I personally have studied the Coanda effect ( Coandă effect - Wikipedia ) but there are a number of inter-related principles of fluid dynamics at play here.

 

[Daver6]

Why not just straight line the airflow?.

View attachment 402145

My understanding is the straight through configuration is actually less aerodynamic in comparison.

 

[Quickstatus]

maximize laminar airflow -

I'm sure laminar flow in jet engines is impossible due the accelerating nature of the flow via the compressor in front and turbine in the rear.

less aerodynamic

thanks but against that would it result in less thrust and maybe more complicated?. I suppose there must have been an overall benefit.

Would TriJets have a role these days given the high performance and reliability of the twins? - say in the southern routes between SYD and JNB/SCL?

 

[StayGoldPonyboy]

Just saw this re GPS spoofing affecting coughpit systems relying on time. Mentions an aircraft from major western airline needing a 'manual reset' taking weeks

GPS spoofers 'hack time' on commercial airlines, researchers say

Creating confusion in the coughpit.

www.itnews.com.au

 

[jb747]

Why not just straight line the airflow?.

The 727 is similar. Always thought it was a "win some, lose some" engineering trade-off thing

I can see structural reasons for wanting the engine, and its thrust to be through the centre of the fuselage, rather than at the base of the fin. The fact that both versions exist in similar aircraft (Tristar vs DC-10) tells me that any differences are probably marginal.

Just saw this re GPS spoofing affecting coughpit systems relying on time. Mentions an aircraft from major western airline needing a 'manual reset' taking weeks

GPS updating can be turned off, so I expect that will be happening much more in the future. I'm not sure that I believe the time could be reset by years, one would hope that there is some form of reasonableness check in any software...though we have seen some pretty poor implementations of software over the years. And a reset taking weeks? Surely they'd just pull the boxes, put new ones in, and any lengthy work could happen on the ground.

 

[flyingfan]

I know pilots are incredibly trained and professional so hope you’ll forgive this pop culture question: What’s the worst sound you can hear in the coughpit?
Is it the fire alarm?
Whoop whoop pull up?
A flight attendant calling about a pax carrying on?
The co-pilot saying their last meal is disagreeing with them?

 

[flyer89]

I know pilots are incredibly trained and professional so hope you’ll forgive this pop culture question: What’s the worst sound you can hear in the coughpit?

Hearing absolutely nothing.

 

[jb747]

I know pilots are incredibly trained and professional so hope you’ll forgive this pop culture question: What’s the worst sound you can hear in the coughpit?

Every pilot will have a different answer. And many nasty things are hidden behind reasonably common noises. The master caution and its associated sounds goes off for a plethora of different reasons. But, how about a very large bang, with no immediately obvious cause.

Is it the fire alarm?

No, not really. A cabin or cargo fire is much worse than an engine fire.

Whoop whoop pull up?

Or 'too low, gear'.

A flight attendant calling about a pax carrying on?

Well, you're not going to get directly involved, so it's a PITA, but that's all (for the pilots anyway).

The co-pilot saying their last meal is disagreeing with them?

I can fly the jet without him.

Perhaps when the FO's snoring wakes you up.

 

[Quickstatus]

QF1
What was the reason?

 

[flyingfan]

But, how about a very large bang, with no immediately obvious cause.

Thought you might say that!

 

[mjt57]

Perhaps when the FO's snoring wakes you up.

Haha.

On another note, there's a YouTube channel called the Mover and Gonky Show with two ex-US military pilots and now presumably, airline pilots who discuss military aviation and other stuff.

Last night I watched one which featured a former RAF pilot. Hilarious stuff. It'd be great to see somone from here feature on the show. hint, hint.

 

[jb747]

On another note, there's a YouTube channel called the Mover and Gonky Show with two ex-US military pilots and now presumably, airline pilots who discuss military aviation and other stuff.

I watch them occasionally. An interesting pair. I think Mover is now a 737 FO, and Gonky a 320 Captain.

Last night I watched one which featured a former RAF pilot. Hilarious stuff. It'd be great to see somone from here feature on the show. hint, hint.

Tell, Richard, I’m sure he’d be interested. Me? No.

 

[jb747]

Would TriJets have a role these days given the high performance and reliability of the twins? - say in the southern routes between SYD and JNB/SCL?

No. That’s a configuration that is dead. Engines are generally the least of your problems anyway. EROPs incorporates many more systems than just propulsion. I think the last attempt at a filling the 3 engine niche was probably the A340, which was simply an A330 with two extra engines.

 

[jb747]

QF1
What was the reason?

It would be the Pakistani controllers setting up the timing/spacing/altitude for entry to Afghanistan.

 

[Quickstatus]

9M-MTJ (MH128 MEL-KUL, A330-300), diverted to ASP due to "engine issues" but then went into a 2hr hold before landing.

Passenger reports say Pilots said needed to "burn fuel".

But 2hrs? And 3.5hrs after departure?

Whats the procedure for an unscheduled landing at an airport outside of normal hours?

 

[jb747]

9M-MTJ (MH128 MEL-KUL, A330-300), diverted to ASP due to "engine issues" but then went into a 2hr hold before landing.

Looking at FR24, it's just done a small step climb from FL370 to FL380, and almost immediately thereafter starts to descend. So, that looks a lot like an engine failure, or at least something that's forced them to pull one engine back to idle. They wouldn't have sufficient power to stay up high on one, so you'd need the descent immediately.

Passenger reports say Pilots said needed to "burn fuel".

Umm... The ability to dump fuel is optional on many aircraft, and the A330 is one. But you can pick which aircraft have the capability by looking at the back of the flap track fairings, as the third one on each side has the dump nozzle. And looking at the pictures, this aircraft was fitted with it. So...not what I'd expect.

But 2hrs? And 3.5hrs after departure?

Alice is about 2,400 metres long, so it should be adequate for a 330 in normal circumstances. But, if they had an engine out, then the landing procedure would probably have them using less flap, which would mean more speed, and so the length might become marginal. It makes me wonder if Darwin might not have been a better choice.

Whats the procedure for an unscheduled landing at an airport outside of normal hours?

This is a comment from the CASA paperwork for Alice.

-Unscheduled operations diverting into Alice Springs require prior notice to the RFFS and Airport Management.​

Not what I'd consider helpful, and and far as I'm concerned ATC can sort that out for me.

If they've had an engine failure, it's now an emergency. Procedurally you just go there, and any niceties that management would like can be disregarded. I think the lighting is on all the time there, and in any event whatever ATC unit you're talking too should be able to sort it out if needed. I don't think Alice had pilot activated lighting (but I could be wrong about that), but it should be in whatever paperwork MH are using.

 

[JessicaTam]

If a four engined aircraft had to land with three operating at an outstation with minimal maintenance facilities, could it be signed off to take off with the remaining three engines?

Or would it be a case of repairing it in-situ regardless?

 

[MooTime]

I'm tipping with 3 engines operating it'll be able to fly to the nearest full service airport.
I doubt that scenario would be possible.