Re: Landing speeds

Date:         13 Jul 97 19:52:41 
From:         Marc Schaeffer <marcmsc@geocities.com>
Organization: None
References:   1
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Peter Coe wrote:
>
> I was hanging out near SFO at the weekend, and had the opportunity to
> watch a United 777 and a United 737 doing a parallel landing.  The
> thing I found surprising was how much faster the 737 was going.
> I would have said the 737 was at least 10% faster on the approach.
> [snip]
> So what's the deal?  Logic says the bigger they are, the harder
> they fall, but apparently this isn't true with aircraft.

I'm not a specialist, but the lines which follow might help.
Don't forget that bigger aircrafts have a bigger wing surface (m2 or
sqft), the phenomena you observed is a relationship between lift
produced by the wing and plane weight at landing. Typical landing speeds
for jets are 240 km/h (for the DC-9/30)
to 270 km/h (for the B747-400).

For the B777-200 landing speed is 250 km/h and for the B737-400 it is of
260 km/h. So you are right *in theory* a B737-400 lands faster than an
B777-200. This means that stretching further the -400 is not possible,
but with the same wing the B777-200 can be stretched. That's exactly
what Boeing will do with the B777-300 which will share the wing with the
B777-200, and thus have a higher landing speed (~265 km/h).

For the A320 and B767 you have the following landing speed :
A319 245 km/h, A320 250 km/h, A321 260 km/h
B767-200 250 km/h and B767-300 265 km/h.
(same wing and weight increases means higher landing speed)

These values can be found at
http://www.geocities.com/CapeCanaveral/Lab/8803/technic.htm

Hope this helps.
-----------
Marc Schaeffer, Luxembourg // mailto:marcmsc@hotmail.com
----> Check out my B767-400/A330-200 homepage <----
WWW  http://www.geocities.com/CapeCanaveral/Lab/8803/main.htm