Digging in the archives 10-14-94 i read a submission from a reader, and then quoted by Cecil in responce to his questionable claims. It was from a "wormologist" who explains that worms are incapable of drowning as in that they have no lungs. Etc.
Well my question to you is, how much faith can we put in Unca Cece's info if he needed a wormologist to tell him hat worms don't drown. Not a critisism of his biology skills, but hasn't he ever been fishing? Does it take a degree to figure that out? And Cece need to be corrected in this fact. Methinks Cecil needs to spend less time imbibing libations and more reading and/or fishing.
The facts expressed here belong to everybody, the opinions to me. The distinction is
yours to draw...
01-16-2005, 09:08 AM
Airline pilot here ...
A lot of folks have come up with great answers to NinjaChick's questions, so I'll try to hit the high points & correct the couple of misstatements.
Good job Broomstick. Bravo.
Original question 1: Jet fuel doesn't vaporize nearly as easily as gasoline. As a result, getting a jet engine started requires a VERY rich mixture, and a lot of unburned fuel is ejected from the tailpipe. That looks like white smoke. Different engine models are more or less prone to it, and all do it more on cold mornings than warm. The Rolls Royce engines on the L-1011 were famous for producing huge clouds of startup smoke. Some 757s are equipped with a variant of that engine which also smokes a bit more than most.
All that is only at startup. Once the fire is lit, all jet engines run quite lean, as that's the way to get good fuel economy which is just about the most important design metric.
Original question #2: The max bank angle you would have experienced after takeoff is 30 degrees, and it was probably more like 20. It feels steep because you're close to the ground, nervous, etc. How rapidly they roll into the bank has a lot to do with how it feels as well.
You didn't say which airport you left NJ from , but if it was LGA or JFK, there are elaborate departure routings to try to avoid flying over houses (fat chance in NYC!). These require relatively strong manuevering within a few seconds of liftoff. Banks angles of 20 degrees are all that's needed, but you do start manuevering much closer to the ground (say 400') than is typical (1500') of other airports.
It's nothing to get excited about; the 100 airplanes that took off on that runway ahead of you, and the next 100 after you, will all do exactly the same thing, hour after hour, day after day, year after year.
Question 3: The thudding from below after parking is the ramp folks unlocking the cargo door, raising it, then crawlng around in there to retrieve all the baggage and cargo. The drill-motor like noise is the electric motor & transmission that raises the door. On large airplanes, like the A300 you mentioned, those doors are the size of household 1-car garage doors & quite heavy.
BobLibDem: Nope. A loop won't work in a big jet. Others have explained the difference between bank angle and G-forces, so I won't go into that. If a jetliner tried a loop they'd make a mess.
They typical way to do a loop is to start out in a slight descent at max power, then when you hit absolute max speed you level off & begin to pull up in the loop. You can only pull up as rapidly as the strenght of the aircraft will permit. Pull too hard & the wings or tail break off.
So essentially it becomes a race between how long it takes to turn through 180 degrees to make the first half of the loop and the rate at which speed is being lost during the steep climb, net of the engines' best efforts to add more speed.
Airliners are 2.5G max airplanes. That means you need a gradual gentle pullup, not at all like an airshow airplane. And the engines are powerful, but not nearly as powerful per aircraft weight, as those on airshow planes or fighters.
Result: if you try a loop, you'll run out of airspeed long before you get over the top. Somewhere around 70 or 80 degrees nose up you'll run out of speed. You need to get to 180 degrees without running out of speed. Waay short.
Once you're out of speed, the airplane will fall. If the ground is far enough away, you may be able to get it pointed the way it's falling and regain control. If not, not.
You'll also have the problem that the engines may hiccup & quit during all that low speed flailing, or break off the airplane. During the falling phase you may lose hydraulic power due to fluid sloshing in the pump reservoirs, which eliminates your ability to control the plane at all. Finally, the controls aren't that big for the size of the aircraft, and if it really starts flailing around, the inertia of all that mass may be greater than the control power available.
Eventually it'll settle down into more-or-less plummetting earthward nose first. Then you have an excellent chance to regain control if the machine is still intact.
But it might have to fall 3 or 4 miles before that happens. And depending on the speed at that point, it might take anoother 2 or 3 miles of room to recover from the dive to level flight. Last of all, durng that recovery you're going to be accelerating like a banshee. At some point you may get going so fast that parts start to peel off.
All in all, a loop is NOT a good idea.
01-16-2005, 09:09 AM
Sorry about that, the hamsters are crazy this AM.
That reply obviously belongs in another thread.
01-16-2005, 10:00 AM
That's got to be a thread necromancy world record. :D
C K Dexter Haven
01-16-2005, 11:16 AM
LSLGuy, email me at firstname.lastname@example.org and I'll get it fixed.
C K Dexter Haven
01-16-2005, 11:44 AM
Nemmine, I see that you reposted.
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