Leaving the flap down until you reach Vfs is gash because you are climbing against unnecessary drag.
Run this one past me again - we have two suggested profiles:
Profile 1
- complies with all regulations
- allows the handling pilot to concentrate on accurate speed and flight path control without interruption for the first 30 seconds after liftoff
- in the event of an engine failure requires the same profile all the way from liftoff to clear of obstacles, and the only difference from the all engines profile is the speed
Profile 2
- does not comply with at least two regulations
- requires configuration changes involving large attitude/trim adjustments almost immediately after liftoff
- in the event of an engine failure requires different profiles depending on where you are in the initial climb
and you think the
first one is gash??!! You have seriously lost the plot there, I'm afraid.
You keep saying there's something wrong about leaving the flaps down for another 30 seconds because it causes drag. This on an aircraft that - if you have done your sums right - can clear all obstacles with the flap down on one engine, and on two is so embarrassingly overpowered that we can't fly a proper noise abatement profile. The flap drag allows us to fly a moderately sensible speed in the initial climb, allowing us to target a speed rather than just an attitude and makes a low level off much easier to handle. A benefit!
Which brings us to
In the event of an engine failure you will ALWAYS be below the path you would be on had you taken the flaps up at the flap retraction speed.
Sorry, just not true. It would be true if you maintained V2+20 or whatever on two engines after flap retraction, but I don't think even you are advocating 30 degrees of pitch. If you maintain a sensible attitude - let's say 15 degrees since that is about the pitch that gives us 190kts with flap 20 - basic aerodynamics tells us that for a given pitch the flight path will be a steeper climb with flaps.
For the Challenger we can even quantify it. If you fly level at 200 kts clean you need +5 degrees pitch. If you select flap 20, you need to pitch down to 0 degrees to maintain level flight; or conversely if you maintained the attitude you would start climbing at 5 degrees - over 8%. That is a huge difference in the flight path.
His Dudeness has posted an aircraft where the final segment is less than the second. From memory all the 500 series Citations are the same, but I haven't got the figures to hand.
Between all those, I think we can say that your theory is well and truly debunked. As I said before, it is not a new idea; such profiles were used when aircraft struggled to climb with flap even on all engines, but modern (i.e. within the last 30 years!) thinking is to take advantage of the better performance from modern aircraft to simplify the handling and cut down on noise.