59 minutes ago, Chock said:

You should bear in mind too that when sources talk about 'the most economical operation of an aeroplane', they don't always mean for the flight you are doing at that time. For example, if you look at most airliner operations, you will find that they tend to fly the airliner at a fairly high throttle setting for the climb to expedite it, but this isn't purely because it is getting them up to cruise quicker for a reduced fuel burn, although that is part of it, it's also the fact that if you use higher throttle settings for less time because your climb is fast, that will invariably put less overall wear on the engine than using a slightly lesser power setting for the climb (which is still a fairly high power setting) but for an extended period of time.

It's the same story with reduced power take offs, sometimes called flex temperature take offs. Most people know that the theory behind these is simply ramming the throttle to the firewall in the hopes of getting the most power, only works on a 'standard day' at sea level (i.e. 29.92.1013Mb pressure), whereas in warmer temperatures when the air is less dense, applying full throttle in an engine without any fancy fuel management systems will mean there is too much fuel and not enough air going into the engine, so it can't handle it efficiently, wasting fuel and also reducing the amount of power the engine can put out to accelerate the aeroplane up to flying speed.

But it wasn't the fact that not doing flex temperature reduced thrust take offs uses more fuel and a bit more runway which made airlines adopt 'flex' take offs, it was the fact that the first airline to do this regularly was Laker Airways when they used the BAC 1-11 and it resulted in considerably less wear on their Rolls Royce Spey engines. Initially Laker developed this technique as a policy in order to save fuel, but it was fairly soon discovered that their 1-11's Spey engines engines experienced far less wear and tear than those with other airlines which were not doing flex temp take offs, meaning their time between overhauls was greater than it was with other airlines and thus Laker's engines were more reliable as well as being a bit cheaper to maintain. This was the real saving they made on costs. It's also slightly more cost effective on tire use too, since with a shorter take off run, there is less wear on the tires.

Tire wear is something Airlines have too look at ? I would have guessed that engine parts and maybe other critical plane parts (like f.e ailerons) would be much more important and tires would be somewhat at the last place, simply for the reason that tires are used for only a really small time on an flight and I would have guessed are under much less stress/wear than other critical parts.  Very interesting to read. 

21 minutes ago, Rucki said:

Tire wear is something Airlines have too look at ? I would have guessed that engine parts and maybe other critical plane parts (like f.e ailerons) would be much more important and tires would be somewhat at the last place, simply for the reason that tires are used for only a really small time on an flight and I would have guessed are under much less stress/wear than other critical parts.  Very interesting to read. 

Here's some pics I took when doing walkaround checks on airliners...

41 minutes ago, Rucki said:

Tire wear is something Airlines have too look at ? I would have guessed that engine parts and maybe other critical plane parts (like f.e ailerons) would be much more important and tires would be somewhat at the last place, simply for the reason that tires are used for only a really small time on an flight and I would have guessed are under much less stress/wear than other critical parts.  Very interesting to read. 

Everything on airplanes is comically expensive, so airlines look at pretty much anywhere to cut costs. Tires on large airplanes are going from 0-100+ knots basically instantly on landing, while also getting several tons of airplane essentially dropped onto them at the same time. If the pilot doesn't get the crosswind correction exactly right, they also get a huge amount of side-loading on them, so those tires are absurdly well built to stand up to that kind of stress on a normal basis, which is why they're usually a couple thousand dollars each to replace. 

For a couple other examples, on the Q400's I fly, the combiner for the HUD (which is just a piece of glass about the size of a paperback novel) costs something like $25,000 to replace (so we get frequent emails telling us to be careful with them), and the carbon brakes are expensive enough that someone did the math and figured out that each individual application of the brakes costs the airline around $10. 

55 minutes ago, Chock said:

Here's some pics I took when doing walkaround checks on airliners...

Oh boy I see those and quite often! LOL Obviously reason for tear and wear is different in my case. We beat every student habit to keep heels on the floor and and avoid holding toe brakes during touchdown! It litterali tear part of tires off! 

47 minutes ago, ndts said:

Everything on airplanes is comically expensive, so airlines look at pretty much anywhere to cut costs. Tires on large airplanes are going from 0-100+ knots basically instantly on landing, while also getting several tons of airplane essentially dropped onto them at the same time. If the pilot doesn't get the crosswind correction exactly right, they also get a huge amount of side-loading on them, so those tires are absurdly well built to stand up to that kind of stress on a normal basis, which is why they're usually a couple thousand dollars each to replace. 

For a couple other examples, on the Q400's I fly, the combiner for the HUD (which is just a piece of glass about the size of a paperback novel) costs something like $25,000 to replace (so we get frequent emails telling us to be careful with them), and the carbon brakes are expensive enough that someone did the math and figured out that each individual application of the brakes costs the airline around $10. 

I knew a G550 captain years ago that told me he would get scolded by the owner of the aircraft if he slammed the brakes too hard on landing because the brakes were absurdly expensive on that bird.

He also liked to fly into airports with short runways. Liked to have his cake and eat it too. Go figure.
 

Needless to say that owner couldn’t keep pilots very long before they quit to fly for someone else.

Edited December 31, 20205 yr by Azapata87
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Why not just wait until you have a huge tail wind in the winds aloft?  That will push you along really well.

12 minutes ago, jspilot said:

Why not just wait until you have a huge tail wind in the winds aloft?  That will push you along really well.

Or even better, set yourself up a nice 200 mph tailwind up above 5,000 feet, so you can get a 300 knot plus groundspeed.

If you want to do this with real-world weather, I suggest checking out windy.com incidentally.

Edited December 31, 20205 yr by Chock