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Fuel efficiency in cruise

Piper Pa44 Seminole FL80 (IR/ME training) ca. 140KTAS 100l/h 0,71l/NM (0,24 l/NM/passenger)

I know the Seminole is less efficient than its predecessor but I don't believe it drinks 100 lph in a 140 KTAS cruise. I think for the purpose of Jason's exercise you are permitted to use the red levers.

P28R-200 (65%) 36lph 0.288l/nm

EIWT Weston, Ireland

By the way when we have more data on here I will publish some tables as it may be of interest.

A380, 3800gph , 27.2l/nm, .056l/nm/pax

EGTK Oxford

A380, 3800gph , 27.2l/nm, .056l/nm/pax

Which is almost exactly the same as a TB20 carrying 4...

I recall the 787 advert giving some figure, which worked out just 20% better than a TB20.

It doesn't matter how you work this; you always come back to a similar figure. Same, I believe, for a train. That all the methods converge fairly closely is probably not a coincidence...

Don't forget to add route charges to anything over 1999kg. It does make quite a difference to the cost per mile.

Administrator
Shoreham EGKA, United Kingdom

Vans RV-8 180 hp, injected, EI:

FL 150 150 KTAS, 0.15 l/nm
2000' WOT 184KTAS, 0.3 l/nm
2000' 16"MP, 2100RPM, 128 KTAS 0.14 l/nm

First and last are LOP.

[edited for line breaks - use 2 spaces at end of line to force a line break]

KHWD- Hayward California; EGTN Enstone Oxfordshire, United States

Don't forget to add route charges to anything over 1999kg. It does make quite a difference to the cost per mile.

I will include an optional column adjusted for route charges. FYI about 24p/nm for my aircraft (2310kg). I am not doing a full cost analysis but only a per mile look at fuel costs to give some perspective for the discussion. What can be clearly seen here is that the difference is not as great as the gph would indicate.

EGTK Oxford

FL 150 150 KTAS, 0.15 l/nm 2000' WOT 184KTAS, 0.3 l/nm 2000' 16"MP, 2100RPM, 128 KTAS 0.14 l/nm. First and last are LOP.

What is 'normal' cruise for you?

EGTK Oxford

Another thing is that most pistons achieve best MPG at some speed only slightly above Vbg, which for say a TB20 would be about 110kt (Vbg=95kt).

But almost nobody flies at such a low power setting.

Administrator
Shoreham EGKA, United Kingdom

PA18-95 Altitude (in compliance of RULE 5) 78 KTAS 0.23l/nm

Oxford (EGTK), United Kingdom

Of course, but this exercise is about real world performance ie what speed/power setting do you actually use. It is simple in the Meridian, you can use any power setting you like - you burn the same fuel, question is just how long it takes you!

EGTK Oxford
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