billreid
Topic Author
Posts: 733
Joined: Fri Jun 23, 2006 10:04 am

Flight Tests Economics Vs Design Economics

Fri Apr 23, 2010 1:17 am

I was wondering how large aircraft economic performance is revealed and the results of different birds testing versus what is expected by engineering.

The MD-11 was an aircraft that did not live up to specifications. When was this discovered and when did sales drop because of this.

I would like to hear about economics of the:
A330
A340, -5, -6
A350
A380

B747 -4, -6
B767, -3, -4
B777, -2, -3
B787 (to date)

DC-10
MD-11
L-1011

What was the expected CASM and what is the true CASM?
Some people don't get it. Business is about making MONEY!
 
JRadier
Posts: 3943
Joined: Mon Sep 27, 2004 11:36 pm

RE: Flight Tests Economics Vs Design Economics

Fri Apr 23, 2010 6:41 am

Quoting billreid (Thread starter):
What was the expected CASM and what is the true CASM?

You can't really talk about CASM as that is very airline specific. It depends on the costs (C) of the rest of the organisation, the number of seats in the aircraft (S) and the sort of routes they fly, so the number of miles (M). That is why for example both Easyjet and British Airways both operate the A320 family, but their CASM is vastly different.
For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and ther
 
billreid
Topic Author
Posts: 733
Joined: Fri Jun 23, 2006 10:04 am

RE: Flight Tests Economics Vs Design Economics

Sat Apr 24, 2010 2:55 pm

Quoting JRadier (Reply 1):
You can't really talk about CASM as that is very airline specific.

You can call it what you want, but my question is not about semantics but rather meeting expectations.

Ever thought about politics though. That was the best non answer I ever heard!
Some people don't get it. Business is about making MONEY!
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Flight Tests Economics Vs Design Economics

Sat Apr 24, 2010 6:21 pm

Quoting billreid (Reply 2):
That was the best non answer I ever heard!

It was a perfectly helpful answer, you appear to not have liked it.

There's no such thing as expected CASM or true CASM for a type (which is what you asked for).

Tom.
 
aeroweanie
Posts: 1577
Joined: Fri Dec 03, 2004 9:33 pm

RE: Flight Tests Economics Vs Design Economics

Sat Apr 24, 2010 7:38 pm

Quoting billreid (Thread starter):
The MD-11 was an aircraft that did not live up to specifications. When was this discovered and when did sales drop because of this.

During design, the engine manufacturers supply to the airframe manufacturer "engine decks" which are computer programs that simulate the performance of their engine. The decks supply fuel flow, thrust, etc. for a given power setting. The decks are for uninstalled performance, so they must be corrected for installation effects. Also the decks are typically optimistic. Most manufacturers audit the decks and reduce the optimism, based upon experience.

On the MD11, McD had a very limited development budget, so they didn't audit the engine decks. When they got to flight test, they discovered that the fuel flows were higher than had been predicted for given flight conditions. A big aerodynamic improvement effort was embarked on and the airframe drag was reduced. At the same time, the engine manufacturers tweaked their engines and got slightly better performance out of them. Despite this, the aircraft didn't live up to the original design guarantees.

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