Vertical stabilizer size question

One thing that catches my eye every time I go to an airport, is the size of the vertical stabilizer of the B737 and B777: the first one has, for its size, quite a large stabilizer, and the latter one has a smaller stabilizer, why is that?


Although I’m not an expert, I’m sure it would be anything ranging from weight distribution, engine size, safety and aerodynamics/fuel economy. Just the way the experts designed it :-)

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I believe it has something to do with crosswind/engine out procedures.


It could be that.

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Or maybe it is the amount of pressure the elevators create as they move up and down to create more controlled flight?

I’ve heard that A318/A319 have bigger vertical stabilizer than A320/A321 due to their shorter body. So would it be the same thing in the 737 and 777? Of course there are many more things than that, but maybe thats part of it.
Just my thoughts.


Bigger aircraft need More lift and Rotation for a small aircraft is easy but it’s hard for a big aircraft so the elevators are bigger.

Yes, but the question is on the vertical stabiliser not the horizontal one.

I have noticed too that the 777 seems to have a proportionally undersized horizontal stabiliser. I don’t know why.

Also it is true the A318 has a taller horizontal stabiliser than the A319/320/321. This has led to at least one incident I am aware of where ground crews didn’t know this and pulled the aircraft in to a hangar which was ok for an A319, only to discover this fact when the tail bashed in to the top of the door. Red faces all around!


And millions of dollars wasted. Its similar with Airbus, the A318 has a huge vertical stabilizer, while then A340 has a smaller one.


Drag. It produces drag that stabilizes the plane. Without it, the plane cannot fly

The vertical stabiliser produces drag? It’s quite thin precisely to minimise drag, although it does obviously produce some.

It is there to primarily provide vertical stabilisation (sorry I know) so prevent yaw and keep the aircraft in a straight line.

The different sizes also correlate to the aircrafts length and natural yaw stability.

A short and stumpy jet like the A318 or 737-600 has less natural yaw and pitch stability than their larger siblings the A321 or 737-900.

Airbus added the extension to the A318 to improve the yaw stability. It doesn’t cost or weigh much and saves having to consider too much FBW software voodoo.

They also extended the A330-200 tail and made it taller than the longer A330-300.

If you think about physics and lever arm moments. Try pushing a door open with your little finger right by the hinge. Then push it right on the outer tip.

It takes less effort the further away from the hinge you get. The longer the lever, the less effort required. The further the stabiliser and rudder are from the aircrafts centre of yaw, the smaller they can be.


Interesting explanation. Thanks.


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