Ask The Pilot

[Quickstatus]

As far as I can recall, all the vanes are doing is setting the flow up for the next rotating stage i.e. controlling and directing the flow.



To be cheeky...I select start, then place a fuel control switch to run. The entire start, including most aborts, is automatic.

Basically, you use an air source to drive a starter that winds the engine core up to about 15-25%. The higher the better. The fan may not be rotating at that point. Fuel and ignition is then introduced, and the core will start to accelerate. The temperature rises very rapidly during this stage. In a normal start the temperature will peak and then wind back to about 60% of that value as the stages accelerate, and normal air flow starts. The starter disengages at about 45-50%. If it doesn't disengage, the start will need to be aborted, as the starter will overspeed. Ignition cuts out at about that point.

In terms of enery

The kinetic energy in turbine drives compressor blades
This energy accelerates air mass
The stator vanes being stationary and acting as an air mass diffuser converts kinetic energy to potential energy - velocity to drop and pressure to rise.

Each compressor stages ultimately causes pressure to increase without increase in velocity

And at the end of the compressor stage most of the kinetic energy of air mass velocity is converted potential energy by increase in chamber pressure by the diffuser. Slow velocity, high chamber pressure and high pressure which aids combustion

I’ll think about this a bit more over the long weekend as I go about chores

 

[jb747]

As long as they make the appropriate noise, I'd just as soon not think about them too much. Have fun.

 

[Quickstatus]

No fun doing chores so needed something to occupy brain.

 

[williamsf1]

I noticed QF2 dep 29/3 seemed to get close to the Russian border and then turn around a circle over Ukraine then continue on. What would be the reason for this? delayed approval into Russian airspace or some other reason?

Qantas (QF) #2 ✈ 29-Mar-2018 ✈ LHR / EGLL - SIN / WSSS ✈ FlightAware

 

[jb747]

I noticed QF2 dep 29/3 seemed to get close to the Russian border and then turn around a circle over Ukraine then continue on. What would be the reason for this? delayed approval into Russian airspace or some other reason?

It would be ATC related. Perhaps timing for separation. Maybe they just couldn't find the overflight clearance.

 

[Quickstatus]

It would be ATC related. Perhaps timing for separation. Maybe they just couldn't find the overflight clearance.

Would this have required resting pilots to return to flight deck?

 

[harvyk]

Has any of the pilots here tried flying drones? If so how well do you go flying them?

Just curious as I was talking to a friend of mine yesterday (a now retired 747 pilot) and he said he had no issues flying a big jet, but put him at the controls of a drone and he has all sorts of difficulty which surprised me a little.

 

[flyingfan]

It would be ATC related. Perhaps timing for separation. Maybe they just couldn't find the overflight clearance.

Is this something pilots have to worry about much, overflight clearance? I would have thought it's a commercial arrangement between airlines and countries and unless there's an MH17-type scenario brewing then by and large airlines will continue to criss-cross the paths they do many times a day as normal, with little risk of a country suddenly arbitrarily threatening to close its airspace.

 

[AviatorInsight]

Has any of the pilots here tried flying drones? If so how well do you go flying them?

The drone I had flown had GPS lock on, basically it holds the position with all the controls neutral. If I move it to another location, it uses the GPS coordinates and basically it has a reference that holds it steady. Take the GPS lock off and it’s back to free flying, which I found much harder to do, using the two little sticks and trying to find which way the front of the drone is, all while being unstable, will take some practice.

 

[jb747]

Would this have required resting pilots to return to flight deck?

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Unless the clearance was not going to be forthcoming at all, I’d expect the FO to be able to sort out some solution, even if that meant using a totally different track. So, to answer your question, no...

 

[jb747]

Is this something pilots have to worry about much, overflight clearance? I would have thought it's a commercial arrangement between airlines and countries and unless there's an MH17-type scenario brewing then by and large airlines will continue to criss-cross the paths they do many times a day as normal, with little risk of a country suddenly arbitrarily threatening to close its airspace.

Normally it isn’t a issue at all. We carry a list of the current clearances in the manuals. But, new routes have occasionally thrown up issues, that disappear as soon as the controllers get used to hearing the call sign every day. If you can’t get a clearance you should be able to arrange a new route on an ad hoc basis, but that may mean you won’t have enough fuel to get to destination. Having said that, I don’t know of if happening.

 

[jb747]

Drones...I haven’t tried flying one, but I intend looking at them as I get close to retirement. But, from what I’ve read, I won’t need to actually do that much flying. The less the better.

I’ve tried flying a model aircraft. The difference in point of view is hard to come to terms with.

 

[Quickstatus]

Can you please explaine what a clearance is and how this works in practice when inflight

I’ve tried flying a model aircraft. The difference in point of view is hard to come to terms with.

Post retirement joy rides at <10000 feet - different POV/perspective? Two engines rent out often cheaper per trip as it’s faster than single engine so engine “on” hours are less and most rec pilots are only rated for single engine - so less demand

 

[jb747]

Can you please explaine what a clearance is and how this works in practice when inflight

Clearances come up a number of ways in a flight, but basically it's approval to proceed via a nominated route to a particular position. First up, you'll be given an airways clearance, which will will include the SID and most of the route. Normally it's the same as the flight plan, but ATC might change it. At each FIR boundary, you'll normally be told something along the lines of 'cleared via xx_ (route) to YYY ( waypoint at the other side of the FIR)'. We just check that that's what is loaded. A direct clearance is approval to go off the plan, bypass any intermediate waypoints, and go to the nominated waypoint. In Europe that's most of the time.

Post retirement joy rides at <10000 feet - different POV/perspective? Two engines rent out often cheaper per trip as it’s faster than single engine so engine “on” hours are less and most rec pilots are only rated for single engine - so less demand

My light twin time consists of about one hour of flying. That was the hour QF paid for during my recruitment assessment. I have no intention of doing any flying after I retire. I consider myself very lucky to have had the career I've had, and to have flown the aircraft that I have...but I intend walking away from it.

 

[Quickstatus]

What did they make you do in that 1hr flying assessment?

 

[jb747]

What did they make you do in that 1hr flying assessment?

It's so long ago, that I truly have very little memory of it. What I do remember is that we did some engine out flying. Which I had never done before. So I just made it up as I went along...must have worked because I was hired only a day or so later. After landing the bloke I was with asked me how many hours I had in the Caribou...to which the answer was zero. He then commented 'oh s##t, you're the knuck'. So I guess he was wondering why my technique was so horrible...and then worked out why.

 

[Quickstatus]

Haha!!
Can’t be that bad if you were hired. Did the assessor you were with have some prior intel?


Got a question embedded in here:
Chinese satellite return to earth

 

[Quickstatus]

How do you estimate visual distance in cruise?

 

[jb747]

You just learn...but it has a large (i.e. massive) margin of error. With towns you often have something giving a distance (FMC or DME distance to the airport). At altitude, you can't see much closer than 20 miles...so that's your starting distance.

Aircraft we generally see on TCAS first, so we know the range.

 

[flyer89]

JB,

Is it true that in the early days of the 380 it was difficult to crew as people didn’t want to move on to it? I happen to know of one current skipper (RD, rostered to take QF1 out this arvo I believe) but I’m not sure how senior he is or what fleet he was previously on.