OK Pilots....got a few questions here....a few things I have always wondered about... [Archive] - Glock Talk

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ATL Peach Girl
06-23-2004, 02:18
Excuse my ignorance for a bit........but I have a few questions about big jets and weights and how they work and other things about planes.......

While sitting at the gate before they push off the thought always hits me "how in the hell can this bird get off the ground with all these people, the fuel and bags crammed into it"??? Yeah I fret about it in my mind...and grip the seat a little at take off......(I don't read or do anything during takeoff....but I sometimes take some pics with my digi cam!!)

Is the plane on a scale of some sort at the gate and they know how much fuel to pump in according to how much the plane weights when fully loaded and do some math by how far they have to go???? I have a friend who works for AirTran here in Atlanta and he mentioned there being some sort of a balance system???

It's true, and I have noticed that when my flights are packed we seem to go down the run way LONGER before we lift off.....and earlier if there is less passengers aboard.......(I like 1/2 full flights--but I know the airlines don't!!!!!) One thing I have noticed too is on the Airliners.Net website is that when a plane is heavy the wings are flipped up on the ends slightly.....not so much if the plane is fairly empty.

And then landings........

Excuse me while I ask, what exactly goes on....?? I hear those darned engines roar really loud at touch down and it seems the rotors inside turn the opposite way they were going.....am I right??? Reverse thrust??? They thrust out the front to get the plane to slow down and stop??? Funny thing is that I don't fear the landings at all.......but rough touch downs kinda scare me some .......

I recall a time when I flew in a prop plane from SLC to IDA (Idaho Falls, Idaho) in December. Idaho Falls' run way was crusted ice.....all the way.......as we landed I could see the runway and I was screaming inside myself "why is this %$#@&^%$ runway NOT plowed"????.....I gripped the seat extra hard and prepared for a total skid off the runway.......but we didn't!!! Can someone explain why we didn't??? If you landed a car on such ice it would have been a nightmare for sure!!

Sorry for such elementary questions. I fly again July 14th and 19th (going to Salt Lake City again).......and having some answers to these questions will help me understand it all more........

AK_Stick
06-23-2004, 03:28
I'm not a pilot but I can answer atleast one thing.


Peach, when you hear the engines spool up after touch down, they have a cup that closes over the exaust and re-directs the air forward, to use as a brake, the engine itself doesn't spin the other direction, it wouldn't work that way, it would push air away from the combustion chamber.....

Yes, the plane will take off faster if it has less passengers, there is less total weight. When you figure a plane may haul upwards of 400 people. Thats 200 people who aren't on the plane, figure about 180-200 lbs per man, and about 110-130 for women, thats a lot of weight isnt it? then luggage and all that. Without the weight, the plane can get off the ground much faster.

The wing tips will be up with a fully loaded plane because the whole wing is acheiving lift, but there is little weight on the very tips of the wings, so they bow up. Maybe a pilot or someone with more knowledge can answer the rest

SlimlineGlock
06-23-2004, 07:02
Originally posted by ATL Peach Girl
While sitting at the gate before they push off the thought always hits me "how in the hell can this bird get off the ground with all these people, the fuel and bags crammed into it"??? Yeah I fret about it in my mind...and grip the seat a little at take off......(I don't read or do anything during takeoff....but I sometimes take some pics with my digi cam!!)

Is the plane on a scale of some sort at the gate and they know how much fuel to pump in according to how much the plane weights when fully loaded and do some math by how far they have to go???? I have a friend who works for AirTran here in Atlanta and he mentioned there being some sort of a balance system???

It's true, and I have noticed that when my flights are packed we seem to go down the run way LONGER before we lift off.....and earlier if there is less passengers aboard.......(I like 1/2 full flights--but I know the airlines don't!!!!!) One thing I have noticed too is on the Airliners.Net website is that when a plane is heavy the wings are flipped up on the ends slightly.....not so much if the plane is fairly empty.

[/B]

Peach, you must above all remember that pilots value their own lives and if it isn't safe, they aren't gonna go fly.

The weight and balance system for airliners is straightforward. The airplane weighs a specific amount without fuel or cargo. The weight of the fuel and cargo are also computed so that you know how much the airplane weighs for takeoff.

Heavy airplanes need long runways to accelerate to a safe flying speed for liftoff. The length of the runway is known, so the maximum weight for that runway can be computed (with safety factors thrown in). Using those figures, the maximum weight for that airplane and runway is used to limit the cargo for your flight so it isn't overweight for a safe takeoff.

The balance part of the system insures that the weight of the cargo is evenly distributed so that the airplane is not nose or tail heavy.

The weight of the fuel is important too, because enough fuel to get to your destination plus safety factors must be in the tanks. That can sometimes limit the passengers or cargo if the runway is short.

There are a lot of folks employed to make sure that this all works out right. Relax and enjoy your flight!

Tennessee Slim
06-23-2004, 10:07
ATL Peach Girl, all wings flex; itís just more noticeable with longer wings. And youíre right, they flex more the heavier the A/C is loaded. The wings on the B-52 bomber, for example, flex down so much when full of fuel that the wing tips can droop and touch the ground when parked, so they put an extra landing gear right on the tip of each wing!

The engines donít actually reverse direction of rotation when they reverse thrust. With jet engines, thereís some kind of mechanical gizmo (it varies depending on the engine) to redirect the jet exhaust to make the thrust go forward instead of backward. With turboprop A/C, the pitch of the propeller blades can be changed so that theyíre pushing forward instead of backward. In both cases, using reverse thrust means a whole lot of additional friction, which is the source of all the extra noise.

Youíre not likely to see it done but jets and turboprops actually can back up on the ground by using reverse thrust. I donít know of any piston-engined A/C that can reverse thrust.

And I wouldnít worry about snow in Salt Lake City in July. ;)

Glenairguy
06-23-2004, 12:55
Aircraft fly because of thrust and a curved wing. The wing creates lift while being pushed because of a principle named Bernoulie (sp).
The principle actually says that air going over the top curve of the wing goes faster and has less pressure than the air going under the flat bottom of the wing. When you see the moving parts of the wing: slats in the front and flaps on the back, it makes the wing more curved for more lift at slower speeds.

The pilots have all kind of weight and balance charts for the specific aircraft available, they get a report from the gate officer with a passenger manifest, they have weight of cargo/fuel and know distance that they are going plus reserve fuel needed after landing. The weight of the aircraft determines the configuration, ie. degree of slats and flaps, which determines the speed of lift off and final approach. If the airplane is light, it takes off at a slower speed. If it is heavy, more speed is needed.

papasmurf
06-24-2004, 02:00
Well, about the ice on the ground, all I can say is that if there is enough air moving over the control surfaces, you are still flying the aircraft even when it's on the ground, and it will go where you fly it. As to the load problem, wings work by suction on the top, rather than from air striking the bottom. The faster you go, the harder the wings get "sucked up" and the rest of the aircraft with them, so the higher the speed, the more weight it can carry. An irresistable force. But wings bullt for high lift do lose efficiency at higher speeds(more drag). Always in life, we compromise. Modern airliners also have tricks such as leading edge slats that grow the wing size for more lifting ability and spoilers etc. to give them an edge. Pilots in general, I believe, care more about their passengers safety than about their own and might fly a marginally safe aircraft if they where risking only their own life(kind of a thrillseeking bunch, but responsible). This is just what I believe. Jeez, I love planes. Always have, always will.

Tennessee Slim
06-24-2004, 10:12
Originally posted by papasmurf
...Pilots in general, I believe, care more about their passengers safety than about their own and might fly a marginally safe aircraft if they where risking only their own life(kind of a thrillseeking bunch, but responsible)....[/B]
I donít agree. As a pilot, I am obsessed with the safety of the A/C because I know that, if thereís a crash, Iíll be the first to arrive at the scene.

M2 Carbine
06-24-2004, 11:04
Peach,

Airplanes fly by magic and helicopters are kept in the air by a determined pilot.;)

Tennessee Slim
06-24-2004, 12:19
Originally posted by M2 Carbine
Peach,
Airplanes fly by magic and helicopters are kept in the air by a determined pilot.;)
Actually, there are two prevalent theories on the subject:
1) Since helicopters were invented by a Russian, they fly by means of a commie plot, and
2) They don't really fly so much as vibrate so hard the earth rejects them.;a

FLMarine
06-24-2004, 18:44
Actually helos beat the air into submission. lol

Wulfenite
06-25-2004, 09:43
Originally posted by ATL Peach Girl
Is the plane on a scale of some sort at the gate and they know how much fuel to pump in according to how much the plane weights when fully loaded and do some math by how far they have to go????

It's true, and I have noticed that when my flights are packed we seem to go down the run way LONGER before we lift off.....and earlier if there is less passengers aboard.......(I like 1/2 full flights--but I know the airlines don't!!!!!)
Sorry for such elementary questions. I fly again July 14th and 19th (going to Salt Lake City again).......and having some answers to these questions will help me understand it all more........

Typically the plane will have enough fuel to fly to its destination, fly to an alternate airport if the destination were weathered in or closed for some reason, and still enough more fuel to stay in the air for another 45 minutes.... AT LEAST. That pretty much the rule for small planes. I wouldent be suprised if the big boys have even more generous safety margins.

WRT runway lengths. The commercial airliners have "balanced field" requirement. What this means is that they have enough runway that they can accelerate to take off speed and abort the take off and still have enough runway left to stop. This requirement virtually guarantees that there's enough runway even if the craft is badly overloaded.

You really need to get out on a discovery flight. Talking to flight instructors you find quite a few that have had students that were there to overcome fears about flying. They dont usually go all the way to get their license but they will often go as far as solo. Its kind of hard to be afraid of somthing that you've achieved a level of mastery over. Also as you get into the process you are exposed to how much overkill is built into the airplanes and pilots.

F14Scott
06-25-2004, 14:44
Don't forget what really makes all aircraft fly:

Lifties!

ATL Peach Girl
06-25-2004, 15:32
I am learning alot guys!!! Great thread!! Thanx for the replies!!

About getting me in a small plane again for a flight lesson.......ummm......well......I don't like little planes......I was in one twice now and didn't like it one bit.......

Wulfenite
06-25-2004, 15:57
I think if you took a lesson you'd find that planes are very similar to guns in that they're a lot less scarry when you're at the controls.

M2 Carbine
06-25-2004, 23:05
Originally posted by ATL Peach Girl

About getting me in a small plane again for a flight lesson.......ummm......well......I don't like little planes......I was in one twice now and didn't like it one bit.......

That's OK Peach.
A little fear of flying is good for your health.


Years ago I was loading my helicopter for a hundred mile trip offshore.

One of the passengers came up to me and said, I don't like this sh**.

I said, What sh** don't you like?

He said, This riding in these helicopters sh**, it scares me.

I said, Don't let it worry you. I've got 10,000 hours in this helicopter and this sh** scares me too.

He got in his car and left.:)

Tennessee Slim
06-25-2004, 23:24
But not as much as hang gliding. That usta give me the willies worse than skydiving.

gamegod86
06-27-2004, 04:01
Originally posted by Tennessee Slim
Actually, there are two prevalent theories on the subject:
1) Since helicopters were invented by a Russian, they fly by means of a commie plot, and
2) They don't really fly so much as vibrate so hard the earth rejects them.;a

My understanding was that helicopters were actually a "collection of parts flying in close formation."
.
.
.

M2 Carbine
06-27-2004, 23:05
One of my least favorite ones is,

Helicopters don't fly,
it's just that they are so ugly the Earth repels them.;f

Dig
06-29-2004, 19:09
Years ago I was loading my helicopter for a hundred mile trip offshore.

One of the passengers came up to me and said, I don't like this sh**.

I said, What sh** don't you like?

He said, This riding in these helicopters sh**, it scares me.

I said, Don't let it worry you. I've got 10,000 hours in this helicopter and this sh** scares me too.

He got in his car and left.

M2, thats beautiful. spoken like a true helo bubba.
:)

Patriot328
06-30-2004, 12:53
Originally posted by F14Scott
Don't forget what really makes all aircraft fly:

Lifties!



I always thought it was money that made planes fly... :)



Fly Independence Air - www.flyi.com - (http://www.flyi.com)

ricky1
06-30-2004, 15:42
M2 Carbine,
That is on of the best line I've read in a while!!! LOLOLOLOLOL

Former Blackhawk Driver
Rick

M2 Carbine
06-30-2004, 22:01
Peach, sometimes boats aren't all that safe.

One morning in about 1970 something I was getting my act together for a trip out to an oil rig from Galveston
A passenger, a cook, told me he was afraid of flying and especially on helicopters.
I told him it's the helicopter or a rough 8 hour boat ride.
He said he would ride the boat.
I called the dispatcher who said he would put him on the boat leaving about midnight.

The next morning I'm getting ready for the sunup flight and in comes the cook again and says I'm going out with you.
I said did you miss the boat?
He said, "No I was on it. The damned thing sank. I still don't like these helicopters but I ain't getting on another boat."



One of our inbound choppers went down on the Louisiana coast.
I don't remember the details except nobody was hurt but it was bad enough to scared one passenger pretty bad.

Our company was sending another chopper to pick up the passengers.

The one passenger said he wasn't getting in another damned helicopter that day.
They were next to a bayou and a Cajun had stopped his boat to see what was going on.

The passenger asked the Coonass if he could get a ride up the bayou to where the passenger could call his company for transportation.

Of course the Coonass said, sure man. (nice people)

Well, some of these Cajun boats lack some things, but it ain't horsepower.

They crashed big time on the first turn, sending the passenger to the hospital.

He got to take the second helicopter ride that day after all. :)

ATL Peach Girl
06-30-2004, 23:51
OMG M2Carbine!!!!!!!!!!!!;P ;P ;P ;P

TheGrinch
07-04-2004, 09:12
Originally posted by F14Scott
Don't forget what really makes all aircraft fly:

Lifties!

Scott is exactly correct. Microscopic entities that love to push against moving objects, these are called "Lifties".

The United States Navy has conducted extensive studies concerning these intriguing critters, finding that most of them live a lower altitudes, that there are less of them out at night, and most frightening, a large area void almost all Liftie activity exists directly behind large, flat-topped warships. The farther from suitiable divert fields, the less Lifties behind the vessel.

Being a particularly resourceful group, Naval Aviators have tried all sorts of methods to attract Lifties to the area behind a ship, all to no avail- extensive seeding with Liftie Food, Liftie baiting, somber Liftie incantations, fervent Liftie prayers (please God, let me get aboard tonight!)- nothing seems to work.

I think the noise of the engines reflecting off of the ship and water, combined with the LSO's screaming scares them away.

It also explains why helicopters fly. The ugliness of the aircraft scares the lifties towards the ground, causing an opposite reaction repeling the helo skyward. This cycle occurs many times per second, causing the whop whop sound that you hear when a helo trolls by. You are hearing the Lifties straining to get out of the way.

Lifties- study them, seek them, talk to them, but above all, learn to love them.

Grinch

STYX
07-06-2004, 15:13
There are old pilots, there are bold pilots, there are no old-bold pilots. :)

I do not recall reading anyone talking about snow / ice on the runway, so I will.

Commercial a/c have limitations on what is acceptable for t/o and landing in both wet and dry snow and ice. For the most part, they can take off w/o ice on the a/c (because it was just deiced by Type I-IV deicer) and are NOT allowed to t/o with ice (there are acceptions for frost in certain locations). As for the snow, I would estimate that they are allowed to t/o in less than 1" of wet snow and 2" of dry snow.
I can tell you that the Embraer 145 flown by American Eagle, is NOT authorized if standing water, slush, or wet snow on the runway is more than 1/2" deep, or if dry snow is more than 3" deep.

As for the safe runway distances, as mentioned, are precalculated before t/o. The non-flying pilot should call out certain airspeeds: V1, V2, Vr. These allow the flying pilot to focus on the flight controls and know what their options are if they have an aborted t/o. Pilots are also trained to expect every t/o to be aborted, so they are prepared for the worst case.

Have a good flight!