for way less fuel (on the 778F then 77F), yes you do see how interesting
General cargo freighters usually fly close to their MZFW and therefore operate on shorter hops. They also generally see much lower utilization than passenger frames. As such, fuel burn, while important, is probably not the top factor in RoI and NPV calculations.*
* - An exception would be FedEx, whom use their 777Fs on very long stage-lengths from China to their hubs in the eastern United States.
It's not the first time that I'm reading on this forum that (general) cargo freighters usually see a much lower utilization than passenger frames. I'm not so familiar with cargo operations but my understanding of it is the following:
- integrators (like Fedex,...) tend to have low utilization of aircraft dedicated to the transcontinental night flights (that's where a low fuel efficiency can be acceptable)
- integrators usually fly less dense payloads, hence are usually more concerned about the fuselage volume than the max payload of an aircraft
- About the general cargo freighters, I just had a quick look at some stats from Cargolux to have an idea of their operational statistics. For the year 2017, they indicated the following:
FTKs increased by 12.3%. Consequently the load factor of the airline increased to 70.1% for the year.
Market demand remained high throughout 2017 resulting in the airline generating a record 131,212 block hours, a 7% increase compared to the previous year. Accordingly aircraft utilization remained high with the daily average utilization in excess of 15:00 hours.
Going by these few bullet points, it's not so clear to me that low aircraft utilization is a constant across the freighter market and especially in the general cargo market. I don't know if Cargolux is an exception in that regards but I'd be surprised that LH/EK/SQ Cargo would display much different utilization patterns.
My conclusion at this stage is that the freighters market is dual: there is a demand for less efficient/used aircraft alongside a demand for new and efficient freighters.
I am not so sure about a 777-8F, at least not in the design now proposed for the 777-8.
IMO the 777-8 design comes out to heavy compared to the 777F. The MTOW increase above the 777F should be 4 t, but the OEW increase should be at least 15 t. The decrease in fuel carried should be far less than on the pax version, let us say 10 t.
The calculation is very rough, but I do not see how interesting a far more expensive 777-8F would be carrying a similar or smaller payload than the 777F.
Trying to save weight, reducing the stretch, or no stretch at all and you could get a better freighter.
Indeed, the OEW of the 778F with the currently known length of the 778 appears to be an issue. On the Sunrise Project, Qantas said at some point that they were waiting for more weight data about the 778, while Boeing said in substance that they had to tweak it to meet Qantas requirements. Now it seems that the fuel capacity of the 778 has been increased compared to the initial figure. Could this be an indication that Boeing has come with a 778 slightly shorter than initially planned? It would make the 778 more suitable for a freighter version, while definitely giving it the range to operate the most demanding Sunrise routes with a full pax load.