Ask The Pilot

[darrend]

Three reds on a PAPI indicates slightly below glide path at 2.8 degrees, not well below, given three degrees is the nominal glide path of an ILS.

You are correct - I just watched the video again and took note of the lights. I really thought they went to 4 reds but it stays at 3. Teach me to take better notice !!.

Also if that is Munich I have been there at times when I've seen them popping out of cloud at a point just short of the threshold so this one is a relatively high cloud base.

 

[jb747]

Three reds on a PAPI indicates slightly below glide path at 2.8 degrees, not well below, given three degrees is the nominal glide path of an ILS.

Not a large number of degrees perhaps, nevertheless, the whole approach looks untidy, and almost like a bit of a 'duck under'. Wipers would have helped for sure...

As to where I'm going...Central Australia, Lakes Eyre and Torrens, and the Flinders ranges. Drive up to Alice on the highway, and back via about half of the Oodnadatta track. Probably do a scenic flight somewhere, but other than that, no aircraft.

 

[Mrmaxwell]

As to where I'm going...Central Australia, Lakes Eyre and Torrens, and the Flinders ranges. Drive up to Alice on the highway, and back via about half of the Oodnadatta track. Probably do a scenic flight somewhere, but other than that, no aircraft.

I've always wanted to do a trip like this in my own backyard! Have a great break

 

[jb747]

I expect to have some level of internet access for much of the trip, so I'll continue answering any questions....but there will be the occasional gap.

 

[Tortuga]

Do you envision any fundamental changes to the design of passenger aircraft in the next few decades and if so what do you think they will be?

I was reading about Iberia doing part of a flight with biofuel - I would love to hear your thoughts on this issue and what effect if any it might have on aircraft performance and the job you do. How realistic is it to expect aircrafts to follow the way cars are being designed based on electric motors and biofuels in the near future?

 

[jb747]

Do you envision any fundamental changes to the design of passenger aircraft in the next few decades and if so what do you think they will be?

I was reading about Iberia doing part of a flight with biofuel - I would love to hear your thoughts on this issue and what effect if any it might have on aircraft performance and the job you do. How realistic is it to expect aircrafts to follow the way cars are being designed based on electric motors and biofuels in the near future?

Well, if the biofuels are displacing food production, then they might be more of a curse than a blessing. It seems the algae method of making them is the most friendly long term. Fuel technology isn't as simple as it might appear. At a pinch a jet engine will run on diesel, or kerosene, and just as likely on the fat from the local fish and chips shop. But, the environment that it is stored in is extremely cold, and fuel temperature is already a limitation that we frequently run into. In fact, the longer the flight, the more of a problem it becomes. It is at least nice to see that the problem is being worked on.

Electric motors. I can't see how you'd get anywhere near the power that you need. Maybe you could have four huge gas turbines as power generators, running small electric motors...and you'd end up with an aviation Prius. Horrid in every way.

Electrics have taken over from some traditional systems already. The A380 only has two hydraulic systems, with extra power being provided by electro/hydraulic compound systems. It saves weight, and to a degree saves on complexity...but, on the other hand exposes the aircraft to forms of multiple failure that are all new.

I really don't see aircraft changing dramatically in my life time. Production cycles are too long, and break even cost points so high, that production only works if an aircraft remains on the line for multiple decades. Look at the 747. 1968 (or so) and still going.

 

[Sifor]

Maybe hydrogen will be our saviour?

 

[jb747]

Maybe hydrogen will be our saviour?

Worked well for the Hindenburg....

Energy density is the issue will all mobile transport. Realistically, I'd expect aircraft to continue to use liquid fuels, even if the rest of the world was using unobtainium.

 

[docjames]

Liquid petroleums (or derivatives) have such a clear advantage in both power per kilo, and power per cost, taking into account practicalities of gas, uranium, hydrogen etc, that until liquid fuel becomes stratospheically expensive, it cant be beaten in an aviation application. Blended plant-based fuels will only win if it becomes commerically cheaper than the current fuels - which means current petroleum based fuel needs to become much more expensive to make the investment in large scale production of "organic" fuels worthwhile.

+1 to jb747 - I'm not holding my breath waiting for conversion to "alternative" fuels in aviation - merely better utilisation of the current - ongoing incremental improvements in fuel used per pax km flown.

 

[harvyk]

I do see a shift to ethanol based fuels, similar to E-10 or E-85, though designed for aviation. I suspect it will one day be cheaper to run planes on that stuff and probably won't require a huge amount of engine mods to make it commercially viable. I expect that minimal modifications to existing planes and minimal training to all involved will be the key, I can not see any sort of alternative fuel being used if it requires a complete rethink \ redesign of aircraft to use it.

Also I do not see a hybrid style plane coming out any time soon, given the sheer weight of batteries, and given a good number of current hybrid cars can be outdone in the fuel stakes by simply using really efficient engines. Plus of course you have the problem with hybrid batteries becoming a huge danger in the event of any sort of crash or even just an emergency.

 

[juddles]

I think the aviation world is so competitive these days that any technology that doessnt match or REDUCE costs doesnt stand a chance in hell. It is simply such a slim margin/highly competitive niche industry.

 

[jb747]

I think the aviation world is so competitive these days that any technology that doessnt match or REDUCE costs doesnt stand a chance in hell. It is simply such a slim margin/highly competitive niche industry.

Manufacturers promising all sorts of savings, but not delivering seems to be the norm at the moment.

 

[DeKa]

Electric motors. I can't see how you'd get anywhere near the power that you need. Maybe you could have four huge gas turbines as power generators, running small electric motors...and you'd end up with an aviation Prius. Horrid in every way.

Also I do not see a hybrid style plane coming out any time soon, given the sheer weight of batteries, and given a good number of current hybrid cars can be outdone in the fuel stakes by simply using really efficient engines. Plus of course you have the problem with hybrid batteries becoming a huge danger in the event of any sort of crash or even just an emergency.

That method of providing power by having a generator drive an electric motor hanging out on the wings actually wouldn't be like a Prius. It would be more like a Diesel-Electric train locomotive, or sort of like a Chevy Volt (but without the batteries and without the 'direct drive' from the internal combustion engine at full throttle at very high speeds). Anyway, I still agree it wouldn't work well.

 

[Sifor]

Interesting read on a 50/50 biofuel blend super hornet.

Navy Tests Biofuel-Powered 'Green Hornet'

 

[mjt57]

Electric motors. I can't see how you'd get anywhere near the power that you need. Maybe you could have four huge gas turbines as power generators, running small electric motors...and you'd end up with an aviation Prius. Horrid in every way.

The gas turbine power plant that we used to operate consisted of 6 generators of 50MW each. Each generator had 2 P&W gas fired aero derivative turbines tacked onto them. Nominally of 25MW each.

To give you an idea of their power output and size these engines shared components with engines on older 707 turbo-jets and newer 737 engines.

I would imagine that an A380 engine could easily run a 100MW generator. And the ones that I've seen at Avalon and down at Mortlake are friggin' huge in comparison. And those are rated in hundreds of megawatts.

So, putting all this into perspective, an electric motor driving a fan to give that sort of thrust or propulsion would weigh 50t or more. Not to mention the cabling, and of course, the generator source, which, in this case, would be something like a RR Trent 900 connected to an equally heavy generator...

Or 4 of them...

And if they decide to burn anything that burns but is susceptible to temperatures, then the cost of trace heating, not to mention the risks involved in using such technology, surely would be prohibitive?

For better or for worse, we're stuck with the status quo, I would think. At least until we run out of the stuff...

 

[mjt57]

Also I do not see a hybrid style plane coming out any time soon, given the sheer weight of batteries, and given a good number of current hybrid cars can be outdone in the fuel stakes by simply using really efficient engines.

A mate has a hybrid Camry. He gets around 7l/100km. I have a Hyundai i30 turbo diesel which gets around 5l/100 km. While the two vehicles are of different classes, it does demonstrate that you can get better economy if you're willing to sacrifice a bit of size and carrying capacity. Both vehicles can carry 5 people, one a bit more comfortably, perhaps and has a larger boot. But in all practicality, most vehicles don't carry much more than 2 or 3 people on a day to day basis.

And there are the costs associated with hybrid technology, too.

Now, unless Boeing or Airbus designers come up with an earthbound version of the starship Enterprise's impulse engines, I doubt that they will be shifting to new technologies any time soon. As for ethanol based fuels, whether it's suited for jet engines or not, I don't know. But the problem using it is being able to manufacture enough to supply the world's airlines' fleets.

 

[james1]

JB - Would like to echo the thanks of others for your amazing contribution to this thread. A seriously great learning experience. Maybe a book deal somewhere for you in the future? Have a great break!

 

[jb747]

Packing at the moment, and hit the road on Saturday. Apparently all of the roads we intend using around Coober Pedy, Oodnadatta, and the lakes are all open again after the recent wet.

Sad news last night (but a little behind the times). For those of you with an interest in military aviation, the US blog Neptunus Lex was a great read. A retired USN Captain, Lex was a vastly experienced F18 and A7 pilot. We had been following him for years. He was killed in an accident in a Kfir, an Israeli made copy of the Mirage III. He'd been flying it for a company that does aggressor training for the USN.

 

[Sifor]

I was an avid reader of Lex's blog, a real shame.

 

[Mattg]

After landing today on a Vietnam Airlines A321, I was quite surprised that the flaps were never retracted. As we got off the plane, they were still literally all the way down. Any reason for this or might they have "forgotten"?