Does fly by wire make for a smoother ride?..

[UALdave]

Is it true that you would get a smoother ride with planes with fly by wire technology? I read that, but I don't know if fly by wire has anything to do with mitigating the effects of turbulence. I would think that degree of wing flex, or other factors, would be more important.

[Gabriel]

Is it true that you would get a smoother ride with planes with fly by wire technology? I read that, but I don't know if fly by wire has anything to do with mitigating the effects of turbulence. I would think that degree of wing flex, or other factors, would be more important.

"FBW makes for a smoother ride" is a too generic statement, since FBW means simply that there is a computer between the pilot inputs and the control surfaces displacement.

In the Airbus version of FBW, when operating in normal law (99.99% of the time I'd say) the airplane tries to keep 1 G (corrected for pitch and bank angles) unless the pilot (human or auto) pulls up or pushes down.

For example, with the airplane hand-flying straight and level and the stick centered, the FBW will try to keep 1G and if a gust starts to accelerate the plane up (tending to put the plane at more than 1G) the FBW will command elevators down to pitch down (even without pilot input) and compensate, trying to keep 1G.

But the FBW reaction is quick but not instantaneous.
If the increase in the gust is relatively smooth, and then the decrease is smooth enough, the FBW should do a pretty good work.
If the gust comes almost instantaneously, the FBW won't prevent an increase in the Gs, and if the gust disappears instantaneously too it will find the FBW pushing down and the result will be less than 1G.

Oh, and add a "theoretically" to all of the above.

[3WE]

I would think that degree of wing flex, or other factors, would be more important.

I would think that wing loading might have a little bit to do with it.

I'm also thinking of the C-5 and that system that dampens the harmonic wing oscillations (I guess by aileron inputs).....pretty cool stuff, but it doesn't elminate them.

[SYDCBRWOD]

The latest edition of Australian Aviation has more on the system installed on the 787. Its an improved version of the Gust Aleviation System installed in the 777. It basically uses a cluster of air pressure sensors around the nose to predict and counteract using the flight control surfaces to some extent the bumps normally felt when flying in turbulent air.

Whilst it may be possible to add a similar system to a wire and bellcrank aircraft, it is simpler to add it to a FBW aircraft. This does not mean that FBW aircraft offer a smoother ride just because they are FBW - this is very much an add-on technology.

[UALdave]

The latest edition of Australian Aviation has more on the system installed on the 787. Its an improved version of the Gust Aleviation System installed in the 777. It basically uses a cluster of air pressure sensors around the nose to predict and counteract using the flight control surfaces to some extent the bumps normally felt when flying in turbulent air.

Whilst it may be possible to add a similar system to a wire and bellcrank aircraft, it is simpler to add it to a FBW aircraft. This does not mean that FBW aircraft offer a smoother ride just because they are FBW - this is very much an add-on technology.

Yeah, I've heard about the sensors on the 787, and I don't know why Boeing isn't hyping that more. I mean, there are a lot of people who are afraid to fly because of turbulence, so if even some of those people hear great testimonies about smoother rides on the 787, then couldn't that translate into more earnings for Boeing and the airlines that operate the 787?

[3WE]

Why isn't Boeing hyping it?

I dare say that you are going to feel turbulence regardless of any reasonable system.

Cessna 150 to 747....there is a fundamental similarity....the planes do fundamentally the same thing.

Then throw in turbulence which ranges from light to severe...

Dampen it....reduce it...sure

There is no practical way to make it go away......

Someone scared of flying is still going to feel some bumps and for some folks- any bump is enough.

Telling them that the plane is turbulence free is some serious false advertising.

[Gabriel]

Why isn't Boeing hyping it?

I dare say that you are going to feel turbulence regardless of any reasonable system.

Cessna 150 to 747....there is a fundamental similarity....the planes do fundamentally the same thing.

Then throw in turbulence which ranges from light to severe...

Dampen it....reduce it...sure

There is no practical way to make it go away......

Someone scared of flying is still going to feel some bumps and for some folks- any bump is enough.

Telling them that the plane is turbulence free is some serious false advertising.

Nobody here is talking about getting rid of turbulence turbulence.

It's like getting rid of the road unevenness. No shock absorber will do that, but some well designed systems can make for a smoother ride.

[MCM]

I also wouldn't be hyping it until its been installed, and proven reliably able to work.

Remember the problems the 777 had initially with supposedly making everyone airsick - being too active and too precise on the controls can be worse than just riding some of the bumps.

Its great they're looking into this sort of technology though.

[3WE]

Nobody here is talking about getting rid of turbulence turbulence.

It's like getting rid of the road unevenness. No shock absorber will do that, but some well designed systems can make for a smoother ride.

No, Gabriel, somebody is talking about hyping it to dispel the fears of fearful fliers.

I belive hyping it for fearful fliers is a bad move becuase I don't think it will give fearful fliers the rock-solid ride they need.

(I will claim some expertise as my mother would grab strangers during "lively" turbulence.)

[Gabriel]

I belive hyping it for fearful fliers is a bad move becuase I don't think it will give fearful fliers the rock-solid ride they need.

Point made.
And further, it would give the (true but better not telling to FoFers) impression that turbulence is frequent and annoying enough that Boeing and airlines are willing to invest quite a buck in a sophisticated device (ok, make that "software") to mitigate it.

[UALdave]

Point made.
And further, it would give the (true but better not telling to FoFers) impression that turbulence is frequent and annoying enough that Boeing and airlines are willing to invest quite a buck in a sophisticated device (ok, make that "software") to mitigate it.

Yeah, those are great points that I had not thought of. I recall reading something about the old L-1011 having had some type of device or functionality that could lead to a smoother ride.

Really, though, the impression that I get, after watching so many W.A.R. DVDs is that pilots do everything in their power to avoid turbulence, but that they can never (of course) avoid all of it.

The most turbulent flight I've ever been on was from KLAS to KDEN back in 1995, during July, on a UAL 737-300. It started immediately after take off-I mention that, because someone asked me how high off the ground we were. The whole flight was pretty bumpy, but that was in hot weather and almost the entire route is over mountains.

[TeeVee]

bah humbug! i like turbulence...it makes the flight more interesting

[SYDCBRWOD]

bah humbug! i like turbulence...it makes the flight more interesting

Agreed.

Reminds me of the old bushie on his first ever flight. Quite turbulent. He calls the hostess and asks for a meat pie - the stewardess says "I'm sorry sir, we don't have any meat pies - I can get you a sandwich or something?" The bushie replies: "Nah I'm after a pie". The stewardess, puzzled, asks: "What makes you think we have pies?" The bushie nods toward the passenger with a sick bag to her mouth in the next row "It's what all them other people are eating init?"

[UALdave]

bah humbug! i like turbulence...it makes the flight more interesting

Well it definitely makes things more interesting, no arguments there! Speaking of which, after take off, I almost always feel this sinking feeling, like I'm in an elevator going down, and it scares me, even though I know the plane is climbing. What the heck causes that??? I have a friend who's a flight engineer on a C-130H, and he said that the plane is actually loosing some altitude when the flaps retract all the way in. That doesn't make any sense to me, though.

[Gabriel]

Well it definitely makes things more interesting, no arguments there! Speaking of which, after take off, I almost always feel this sinking feeling, like I'm in an elevator going down, and it scares me, even though I know the plane is climbing. What the heck causes that??? I have a friend who's a flight engineer on a C-130H, and he said that the plane is actually loosing some altitude when the flaps retract all the way in. That doesn't make any sense to me, though.

At some point the pilots pitch a bit down to agin more speed to retract the flaps. Initialy that reduces the climb rate. While the plane doesn't stop climbing, the change from say 3500fpm to 2000fpm is felt like going down (in fact, it's the plane flying at less than 1G for an instant to reduce the vertical speed).

Shortly after that, the plane will increase its vertical speed again and you feel like in an elevator starting to go up.