PPRuNe Forums - 737-800 Landing Speed

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Quote:

Originally Posted by Kakaru (Post 10241889)

I doubt to be honest. The A321 for example is not known for very high approach speeds, despite higher overall weights. Flap design (with multiple slots as on the A321) can make a difference. MTOW is not really an indicator here. The maximum landing weight needs to be known.

The Max 9 is listed at 74.3T so it will be somewhere close to that I would assume.

How much more can they do before they lose the type-rating? If you are talking redesigning flap systems what relationship is that to the certificate? I am assuming they can't add any more stages of flaps so it's only a few aerodynamic tweaks and how much difference will that make? Personally I suspect this thing will be coming in like the Space Shuttle unless there is some aerodynamic changes they can sneak in there.

Quote:

How much more can they do before they lose the type-rating? If you are talking redesigning flap systems what relationship is that to the certificate?

The 747-8 has an entirely new flap system (and a largely new wing) relative to the 747-400. It can be done - it just a matter of how much Boeing is willing to spend when it's unlikely it'll be a big seller. Even they admit the -10 is really only a stop-gap measure until the MMA comes on line.

Quote:

Originally Posted by neville_nobody (Post 10241944)

The Max 9 is listed at 74.3T so it will be somewhere close to that I would assume.
...
Personally I suspect this thing will be coming in like the Space Shuttle unless there is some aerodynamic changes they can sneak in there.

Well, in order to reduce the stall speed (thus Vref and approach speed) they have 2 ways to do it (they can use one or both methods), but with subsequent structural stresses and weight penalties:

1. Increase the maximum CL for landing flaps only (not for the design airfoils as that will negatively affect the cruise performance) by implementing a blown flap (using engine bleed) and/or increase the number of fowler flap slots (yet that increases maintenance costs as it happens with the Classics) and/or increases the wing's aspect ratio (by increasing the wingspan only), which reduces the wing loading.
2. Reduce only the wing loading by either increasing the chords lengths alone (but this reduces the maximum CL by some amount) or simply increase the wing as a whole without affecting it's aspect ratio.

So, most probably as it is right now, the MAX will require a bit longer runways due to higher touchdown and approach speeds in comparison to the NG.

Quote:

Originally Posted by ImbracableCrunk (Post 10240653)

Vref=1.3xVso isn't a hard rule on the 737.

Also, there is a checklist for this situation. My QHR calls it "All Flaps Up Landing." Vapp=Vref40+55.

Thanks you! The resulting speeds seem much closer to what would be expected for no LE/TE devices extended. Again, I couldn't find such information yet, but the result is very plausible!

Regards!