dzsoki

So I'm looking at my OKA-IAH route, where I have a340-200 and 777-200er flying.

 

A340-200 has 4 engines, each with a fuel flow of 39,936, and the per-flight fuel cost is $283,404

 

777-200er has 2 engines, each with a fuel flow of 45,203, and the per-flight fuel cost is $325,084

 

How in the world is the a340 cheaper? By my estimation it should use almost twice as much fuel, especially considering it travels slower than the 777.

This is also a good example that these raw engine datas are misleading to calculate the actual fuel consumption of an aircraft.

Here are the raw datas:

A340-200

engines: 4 x CFM56-5C2

thrust: 4 x 31200 lbs

TSFC: 0,32

Fuel flow: 4 x thrust x TFSC-> 39936

777-200ER

engines: 2 x Rolls-Royce Trent 877

thrust: 2 x 80720 lbs 

TSFC: 0,28

Fuel flow: 2 x thrust x TSFC-> 45203

As you can see Fuel Flow Rate calculated from the efficiency and the maximum thrust of the engines.

But in the real world this maximum performance won't be used even in take off, climb out conditions the engines will operate at a much lower thrust. During the majority of the flight time, the engines will operate in cruise mode.

This cruise mode is used for 80-90% of a flight, and this depends on much more parameters, than the above mentioned raw engine datas:

-aerodinamics of the aircraft (wingspan, design, engine cross section, winglets)

-weight of the aircraft (passengers, baggage, cargo, aircrafts own weight, fuel and reserves, engine weight)

-engine parameters (cruise SFC)

-service ceiling

etc. etc.

In this example, these aircrafts required to handle the fault of an engine at take off. This is why the two engine equipped Boeing required to use a much higher maximum thrust engine vs. the four engine equipped Airbus. Also all two engine equipped aircraft has a certification, which determines how long it can fly with one engine. When you assign a route to a two engine aircraft you have to calculate with this one engine max. operation time, to always have a diversion airfield within that one engine operation range.

ETOPS certification

In real world normal operating conditions Boeing 777-200ER's huge 160000lbs thrust won't be used (this is a built in spare performance for take off and ETOPS), and this misleads the fuel calculations here. In this metrics the four engine aircraft have better raw engine data.

Actually the Boeing 777-200ER has a better fuel consumption here, but the A340-200 also good.

You can compare the datas here with a 6000nm example: http://theaviationsp...ion_dataset.gif

(burn off fuel, passenger only)

Also to give an example about the cruise fuel consumption you can check this picture:

This is an actual fuel flow measurement during a flight of a Fokker F100 aircraft where both engines measured separately (blue/red dots). The fuel consumption measured in KG/hours (1kg/hour means 2,2 pounds/hour)

You can clearly see the three main stages of the flight:

- take off / climb out,

- cruise, 

- descent,

I like these demo pictures too.

I think the physical aircraft cabin sizes will be an interesting addition to the new version. As the fuel flow, speed, turn time, required runway lenght and other parameters currently have to be considered, the actual cabin size and the chosen seat configuration will be at least as important in the game, and also balances some aircraft types which I mentioned before.

I dislike taking a specific target on "old", given many airlines have had successful business models while using old planes. [ValuJet, Allegiant, Very likely Ryanair during their BAC-1-11/737-200 period. ].

The quoted approach is still very soft. For 15 years depreciation would remain the same, then from 15 years increasing maintenance costs would kick in, and after 25 years of age, the not worth it period would start.

So this would penalize extremely large, irrealistic fleets and also extremely old, not maintained fleets.

In 2003 Ryanair was operated 21 737-200 aircrafts with age between 21-24 years, then they sold their aircrafts in 2004 to have one of the the youngest fleet with their new 737-800's.

So this is fully matches with the recommended profile.

Also here is an article about their latest order of 175 Boeing 737-800:

http://www.cnbc.com/id/100827382

Ryanair's announcement will see 75 of the 737-800s replacing old stock with the other 100 representing totally new aircraft. The 175-strong order will be delivered over four years between 2014 and 2018.

1) realistic order queues 
2) limiting IFS prices (eliminating scam ifs but still making profit possible)
3) realistic utilisation (I know aircraft technically can keep their aircraft going that long but how many people are going to want regional flights at 3am   ? I can tell you now: pretty much nobody   )
4) loadfactors: very rare do you actually get 100% loadfactors so even with the default price (which brings me onto my next point), airlines should only manage 80-90%
5) the default price is fairly high... I don't need to say any more 
Feel free to sum up   those are a couple of main things because anything I can think of is nitpicking 

Good ideas, just would like to extend these with the following two points:

1, The current depreciation rates are good for approx. 10-15 years, but they need to be corrected after an aircraft becomes older.

Here is an example about a top4 airline with 35 years old average fleet age in 2015, working successfully regarding economics.

In the real world, different engine maintenance, airframe integrity, C, D checks are very expensive. Lots of aircraft scrapped, because its simply not ecnomically viable to maintain them anymore.

Easy solution from programmers point of view to better simulate these increasing costs:

-the current depreciation rates should be doubled after an aircraft reach 15 years of age

-the current depreciation rates should be tripled after an aircraft reach 25 years of age

-here is an examle: http://img854.images...4/8138/v51k.jpg

suspected effects in the game:

-this change would make it harder to maintain extremely large fleets economically

-also you have to replace your aircrafts regularly, if you want to stay competitive

(if you have 2-300 aircrafts from one type, you will simply won't be able to replace them with 2-4 weeks production rates)

-small airlines with younger fleets could race better against big airlines with their lower maintenance costs

-old and higher depreciation rate aircrafts would have to be replaced even faster with modern ones

-if we consider that most of the aircrafts in AE runs between 120-140 hours a week, it means higher utilisation than in the real world

2, legroom should be taken into account more strictly on long range (over approx. 2500 miles flights)

-a fully crowded 28" tiny seat pitch aircraft should be nearly empty on intercontinental routes

-for long range flights, passengers cares more about legroom compared to short range flights

 

 

But then again there are different size seats

We have the actual cabin floor area in the quoted parameter: Seating @ 1 PAX / square meters.

If we take this as a reference for example with 34" seat pitch, we can compare the different seat configurations to this.

-B777-300ER: Cabin floor area: 3555 square feet Seating @ 1 PAX / square meters: 330,4

If I configure 550Y it will be 67% (550/330,4) denser than our 34" reference. --> legroom parameter

If I configure 16F 40C 200Y it will be 29% (256/330,4) more spacious than our 34" reference.

-A340-600: Cabin floor area: 3380 square feet Seating @ 1 PAX / square meters: 315

If I configure 375Y it will be 19% denser than our 34" reference.

If I configure 16F 40C 200Y it will be 23% more spacious than our 34" reference.

The actual dimensions of the aircraft taken into account in this calculation, this is why the full Y config get better results for the A340 and the same three class seating is better for the 777-300ER.

Of course if we use different types of seat pitch not just 3-6 different classes with preconfigured values, it will make this much more sophisticated, as you have to know the dimensions of the seats etc. eetc.