Boeing 787 cruise altitude
 

Does anyone know what the 787's typical cruise altitude will be? Will it be in the 40s or typically the high 30s?

MACH 0.85 (0.89 MAX) at 40,000 ft (MAX CRZ ALT) ...
Best regards, :)
fredgrav

The FCOM says max operating altitude is 43.100.
Optimum cruise level is between FL350-430 depending on weight.
(500-300.000lbs)

XPM

Errr...m,
XPM....QF411's talking about the 787. Just thought u'd missed that out.Cause i did too initially...
fredgrav's right..
Ta..

Well, I'm ALSO talking about the 787, what is your source of information?

I just downloaded the B787 FCOM from myboeingfleet.... The maximum operating altitude is listed as 43,100 feet. Their sales people are offering it as a M0.85 aircraft.

Mutt

0.85 at what Cost Index?

These days most operators fly at very near maximum range cruise.

What would be it's ecom Alt and Mach at, say, MLW + 20 000KG at CI of 80?

G'day mutt,

How do you get authorisation the access the 'myboeingfleet' website?

I'd be interested in having a look at the B787 FCTM. I'm a little surprised it's even been published considering the airplane has yet to be certified.

Regards,
BH.

P.S Mutt, I had a bit of a dig around the myboeingfleet website and it looks like I can go through my company Boeing rep.

We are a 787 customer :):) The FCTM was issued over a year ago.

Mutt

LR cruise;
MLW is 370.000 lbs, + 20.000 kg = 414.000 lbs
Opt alt FL390
M.848
FF 5346/eng

Expect revisions to the numbers.

XPM

If it meets those numbers then...

I want one!!!

That is impressive!! Thank you for your replies. Very informative!

All the B787 manuals are published including the FCOM 1 & 2 along with the FCTM and the combined FCTM for the 777/787. ALL have big disclaimers regarding their use and accuracy at this hour. Actually the latest version is Revision #3 if I'm not mistaken. Also, most if not all B787 material will be delivered elctronically and not in a paper version.

XP is the Fuel Flow in lbs/hr or kg/hr? Impressed if in lbs....

Must be lb/hr. I'd be deeply UNimpressed if it was kg/hr per engine, and even slightly unimpressed if it was total fuel consumption.

:ok:

Way too early to start making performance assumptions but !


XPM,


Not sure why you are mixing up pounds and kilograms. Are you saying that at 414000lbs the numbers you quote are expected ?



Because those numbers look about midway between a 767-400 and the -200 and i'm not impressed.



I must be missing something ?

Stilton

You are..:ok:

Comparing the 787 with the 76X cruise FF at the same GROSSWEIGHT will
only tell you the AERODYNAMIC- and ENGINE EFFICIENCY difference between
the two planes. The 787 will win here but not by a huge margin.

HOWEVER;

The B787 airframe and etc composite structure is much LIGHTER than
the B76X (operational empty weight).

SO, Imagine the B764 and B787 flying the exact same trip with the exact
same payload/pax. Due to less structural weight,
the 787 will ALWAYS be lighter than the B764 for the same flight.
This means;
- It also needs to plan LESS trip FUEL than the 764, making it even lighter
- Being significantly lighter, it will cruise HIGHER than the 764 on the same trip burning even less.
- It cruises faster -> gets there sooner, which means the 764 engines
will still be burning fuel when the 787 has parked.

If we add all this up the total effiency of the acf is supperior.

It's a bit like adding winglets to a 737. The aerodynamic gain is about 2%.
However, having to plan less trip fuel and thus always being lighter & cruising higher, the total fuel
gain will be 4-5 % on the winglet acf.

M

The expectation was the 787 would have 757 fuel burns with 777 range.




Looks like 767-300 fuel burn with who knows what range to me..

Greetings,
For the fuel they talk about 25% less then the B767 , baring in mind that B767 is a .80 cruiser :}

Supposedly 20% +/- more efficient.