Nonstop flights use more fuel than flights with a Tech Stop?

[MattDell]

I recently changed a flight from London to Australia from a flight with a tech stop to a nonstop flight, thinking that it would increase demand and lower costs without the airport fees of the 3rd airport.  Now, I can't compare directly to a tech top flight to this particular airport since I changed them all, but my flight to another airport in Australia is around 1,000 miles farther and has a tech stop, yet uses less fuel than my nonstop Australian route and is far more profitable.

The only thing I can think of is the extra weight of the fuel needed to fly that far.  Is that modeled in here?

And if that's the case, is it safe to assume that a flight with a tech stop will always be more profitable than one without?

-Matt

[Powi]

I cannot answer your question directly, but I'll provide some observation concerning the matter.

Last time I asked Sami, fuel consumption didn't change depending how far you flew. It was always according to MTOW.

In real life (ultra) long non-stop flights consume more fuel than ones with a tech stop. Shorter flights should consume less when flying non-stop.

Demand disadvantage in the game for a tech stop seems to be minor.

[swiftus27]

There actually is a reason for this one.

It takes SO much fuel for a plane like the A340 and 747 to fly a long distance that the extra weight from the fuel requires them to have even more fuel on board.  This is due to the fact that getting all of that fuel into the air is not very easy at all.   The further the distance, the more cumulative the effect is. 

If you fly from JFK to LAX on your way to Narita, it may take less fuel than a direct flight. 

[JonesyUK]

Is that modelled in the game though? IRC Powi is correct, you can fly 100nm or 10000 nm and the fuel consumption will stay the same per hour.

Only thing I can think is whether the planes have different engines or a different MTOW?

[Sigma]

I've got plenty of planes sitting around, let me test it right quick.  Give me a few hours to let some time pass and we'll see.

[LemonButt]

Another variable to consider is fuel prices.  The fuel price listed is an average with actual prices varying by airport.  If you are purchasing fuel at two different airports, there is going to be a discrepancy.

[Sigma]

Alright, well my testing came to quite the opposite conclusion from the OP, and is the one that I would have expected.  I chose a route that I knew had another major airport right along the flight path at pretty much halfway.  The route with the tech stop only has to travel an additional 3 miles (about 0.2% further) over the full course of the route.

DFW-JFK (1206NM) -- averaged $20,450 in fuel costs
DFW-SDF-JFK (1209NM) -- averaged $24,501 in fuel costs

It was a tech-stop only in SDF and load factors were virtually identical between the two routes.  The planes were new and were identical sequential deliveries.

That is a difference that is appreciable enough that I doubt is completely related to differing fuel costs between DFW and SDF.

[LemonButt]

Another factor to consider is inertia--an object in motion stays in motion unless altered by other forces.  Taking off and going from 0 to Mach 0.8 takes a considerable amount of fuel.  Taking off twice and cruising 90% of the distance is going to take more fuel than taking off once and cruising 95% of the distance.  Albeit a more complex model, it make sense it takes more fuel with the extra stop.

[swiftus27]

A huge reason that 4 engine planes are being phased out is due to the fact that they need os much fuel to run.  It is the weight that needs to be lifted off of the ground (I.E. more fuel) that causes you to need even MORE fuel just to get the aircraft up there.   Again, it is a cumulative effect.   

Let's say it normally takes 10kg fuel to go 100nm (I know this is horribly innacurate) in normal conditions.  Perhaps when you are flying a fully loaded A340 with max fuel, it takes 13kg to go the same distance.  However, when you do it in two short hops, you keep the 10kg per hour. 

Sure takeoffs and landings consume a lot of fuel, but being loaded 50% weight seriously reduces the thrust necessary to get the plane back in the air. 

[Sigma]

Sure takeoffs and landings consume a lot of fuel, but being loaded 50% weight seriously reduces the thrust necessary to get the plane back in the air.  

If the plane was made up entirely of its fuel and just that fuel, then yes, the energy output required would be essentially the same in both circumstances.

However, the vast majority of the weight of the plane is the plane itself and its payload, not its fuel.  Reducing the fuel at take-off by 50% only reduces the amount of weight that needs to be lifted by a relatively small percentage of the total weight.  Depending on the plane, the maximum fuel load would be 20-30% of total MTOW, so half fuel capacity would only reduce the take-off weight by 10-15%.   As such, the plane with the stop halfway doesn't get two takeoffs at 50% of the weight it would be at compared to non-stop, it gets two takeoffs at 90% each, adding up to a cumulative increase in the energy needed to travel the distance if a 2nd takeoff is required.

In the example I posted above, the plane at non-stop is only loaded with about 1/3rd its fuel load to make the trip non-stop -- so only 10% of its' take-off weight is fuel.  Stopping half-way for fuel would reduce its take-off weight by 5%.  The 500% increase in fuel consumption made during the climb to cruise a 2nd time would significantly offset any weight reduction.