Boeing 737 Cruising Attitude

[Atlantean1963]

I’ve been paxing on 737s a lot more than usual recently, and one thing I have noticed is that when cruising, the 737 seems to have much more of a “nose up” attitude than (for example) an Airbus A320 (and I'm not using the phrase "nose-up attitude" in the same sense that I would apply it to my 14 year old daughter :))...

When this is coupled with the apparently completely frictionless material from which the tray tables are manufactured; then I seem to spend quite a lot of the flight trying to stop my computer/meal/cup of tea sliding off the table and depositing itself in my lap. :uhoh:

So two questions really:

For the proper pilots – why does the 737 fly in this manner?
For my fellow SLF – any ideas how to keep stuff on the table?

Thanks in anticipation,

Atlantean.

PS: - Mods, please feel free to move if deemed necessary

[Hombre]

I am a lowly SLF too but fly every month on GSM 737s.

I know that very few aircraft fly level as the best config for economic fuel burn/aerodynamics is a couple or more degrees off horizontal..737 drivers will know the correct angle.

I would of course concur with your view on the frictionally challanged tables. I use the napkins provided to cover the surface and always ask for more if necessary. Never ever wear white trousers!!

[plumponpies]

Cruise pitch in the 738 is about 2 degrees nose up.

[Atlantean1963]

I can now report that Malev's 737-800s have tray tables with a much higher co-efficient of friction than LOT's 737-400s. My trousers now feel much safer.

One day, I might even get a life. :)

Best Regards,

Atlantean.

[Wyle E Coyote]

how do you judge pitch angle as a passenger? you have no reference point

Acceleration feels like an increase in pitch angle so what you are probably experiencing is the fantastic leg strength of the Boeing gerbils, over their French counterparts.

-The Gerbils wind up the rubber bands in the engines (That's the abridged version of gas turbine theory. don't ask for the long version)

[Final 3 Greens]

how do you judge pitch angle as a passenger? you have no reference point

Try a glass of water.

[Wyle E Coyote]

Aha! nice theory, but only a suitable indicator under continuous acceleration and even then, g forces will modify how the glass of water behaves, as Bob Hoover demonstrates Here (http://au.youtube.com/watch?v=Xp2Uc9XvmjY)

[Final 3 Greens]

Stand the glass of water on the tray table and note the angle of the water against the side of the glass, if we assume that the tray angle is similar, a relative reference can be made.

If you read the OPs comments, that's all he is saying.

Bob Hoover never rolled an airliner to my knowledge, so nice video, but not relevant.

[Wyle E Coyote]

Only under constant acceleration. If there is forward linear acceleration, the g forces are tilted rearwards, moving the water to the rear of the glass, and indicating (to you at least) a nose up pitch.

The video demostrates quite nicely that the level of a glass of water isn't a good indicator of bank or pitch, because there are too many acceleration forces to consider.

The size of the aircraft is irrelevent here, airliner or otherwise, the same laws of physics still apply.

At the end of the day, the answer is still the same. Gerbils.

[deltayankee]

It's true that a glass of water will not work as an artificial horizon in turns or any acceleration, but here we are talking about stable flight in the cruise.

But since when did Boeing go to the trouble of calibrating all the tray tables so that when open they are exactly aligned with the longitudinal axis of the plane? Isn't the slipping drink problem more likely to be the fault of tables people have sat on?

[Wyle E Coyote]

the point I was making is how do you know you're in level flight? you have no references with which to make that assumption.

I can't believe I'm still debating this. I need a life too.

[PAXboy]

how do you judge pitch angle as a passenger? you have no reference pointFirstly - my ears can tell me that and, yes, I know all about adapting to the prevailing conditions when in stable cruise! The main notifications of angle are:-
Drop a bottle of water/wine or tin (hopefully unopened) although it is more fun to watch someone else do this - especially if they are safely across the aisle.
From the lavatories at the back - walk up hill to return to your seat.
Watch the CC pushing the carts up the hill and braking them on the return trip.I'm only writing this to help Wyle E Coyote feel less alone although, by now, he will be wishing he had gone to bed with a cold towel on his head. :8

[GwynM]

the answer to the original question is to spend a lifetime drinking real ale, and then prop the table on your beer gut so any spillage rolls forward. It works for me

[Atlantean1963]

Wow, I had no idea I could start such a debate!

Mr Coyote - you can't fool me! Of course I know that they don't use gerbils to power the engines - their tails would get caught in the compressor blades. Which is why they use hamsters instead. ;)

And thank you PAXBoy for providing the real-life empirical evidence to support what I feel on a 737. I did use the word "seems" in my original post. And I was really talking when the plane has reached crusing height. I can't believe that it accelerates for the whole flight....

I've decided not to get a life after all - it's much more interesting on pprune... :}

Best Regards,

mark.

[Pax Vobiscum]

Look out of the window at the horizon - judge the angle it makes with the 'horizontal' edges at the top and bottom of the window (or slide the blind down if you like). This may not work too well over the Himalaya or the Rockies, but it's reasonably accurate over water. :)

FWIW I've never noticed any difference in this characteristic between a 737 and A320.

[strake]

Well, here's a real anorakky procedeure....

When at altitude on a clear day, close one eye and line the other up on the small round vent at the bottom of the window. Watch the vent in relation to the ground (fields, roads etc). You really get a good impression of the speed of the aircraft crossing the earths surface...

Normally, I'm very very bored when doing this.......

[PAXboy]

Normally, I'm very very bored when doing this.......But not quite as bored when sitting at your computer of an evening browsing through PPRuNe, eh strake?? (Yeah, yeah, I know I haven't a leg to stand on!)

The strongest nose up pitch I have experienced was Concorde and perhaps someone can give us the exact degrees ...

As further evidence to the sensitivity of my semi-circular canals (perfectly formed they are :ooh:) there have been countless times when I have been reading or watching the movie, or dozing whilst listening to music and I realise that we are changing attitude and I look out the window ('A' and 'E/K' are the only seats to have) and I can j-u-s-t see the change against the horizon. There does not have to be a change in RPMs, just the slightest change will be picked up.

Now, all I have to master is being as sensitive in the areas that really matter to the other 50% of the planet's occupants... :confused:

[TightSlot]

Usually, I identify the smallest FA on my crew, and then invent a totally spurious reason for them to push a catering cart from the rear galley to the front. When closely timed, this will enable me to calculate the precise attitude of the aircraft, and when indexed against the cabin altitude as measured by the breathlessness of the FA afterwards will permit a Mach calculation approximate to 1 decimal place. Descent rate may also be calculated by reversing the process.