.png.3b3332cc2256ad0edbc2fe9404feeef0.png.8488ab72b8bb2e508209bfe3211b6e08.png)
FAA’s Diversity Policies Under Fire After Deadly Air Collision
-
Recently Browsing 3 members
Announcements
-
Topics
-
-
Popular Contributors
-
1
-
2
-
3
-
4
-
5
-
-
Latest posts...
-
30
Pentagon Intelligence Agency Halts Observances of MLK Day, Black History Month, and More
I'm sorry but the tired old it's being thrust in our face line wont work. You again avoid specifics but if it's Pride marches your getting yourself into an unnecessary tizzy about then avoid them. The whole idea of a march, a protest or a demonstration is about visibility. If you euphemistically describe that as being thrust in your face that's a problem you have to address. If it's Pride meetings etc. then again you're not obliged to attend so don't fret about it. If it's the whole movement you're irked by then you're just gonna have to deal with it. As for ladyboys, I'm guessing you personally have never been pick-pocketted by one, (or probably anyone on this site) so why does it exercise you're thoughts? -
7
Our Hostage Daughters Long-Awaited Return: Why Did It Take So Long for the World to Care?
Gosh. I wonder if there's any significance to the temporal correlation between the change in the Oval Office and the release of hostages. -
76
Thai airline flight makes emergency landing in Phuket
I guess it depends on your definition of emergency. To me - a single-engine aircraft pilot - an emergency is no power. This recent incident had the huge benefit of one remaining engine. Given that jet engines are usually extremely reliable, it is safe to assume that controlled flight could have been continued for several hours until the fuel ran out. Firstly, a plane still has adequate directional control and can maintain flight with one engine (or a minimum of two for a four-engined airliner (B747, A340). Even if both [all] engines fail, aircraft don't fall out of the sky - they can glide. They still have adequate directional control but now only in three directions - left, right and down. The 'up' option is removed. Having said that, if we use the A320 as an example again, the glide ratio with no engines is a very healthy 17:1 at the best glide speed of 230-250 knots. This means that for every 17 feet horizontally it goes down 1 foot. In 2001, an Airbus A330 (which has similar glide characteristics to the A320) glided 75 miles from 33,000 feet after running out of fuel, successfully landing in the Azores. So, unless you are mid-Atlantic, there are options. For context, let's contrast engine-out performance (and actions) with a helicopter. As you can imagine, the main rotor blades on a helicopter beat the air down, keeping the helicopter in the air. The angle that the rotor blades present to the air is controlled by the collective, a handle looking like a car handbrake down to the pilot's left (helicopter pilots traditionally sit on the right of their cockpit; aircraft pilots on the left). To take off, the power is increased and the collective is lifted (sometimes, the throttle is automatically linked but let's not get distracted). To lower the helicopter, or land, the collective is lowered. Having explained the collective, you will now appreciate that if the engine loses power, the rotors only have their own inertia and will slow down rapidly. This is not a good thing. The rotors rely on the engine, of course, but also centrifugal force. If the rotors slow down, centrifugal force diminishes, and the blades start to flap upwards (it's called coning). It's probably all over once this happens. There is a small moment of opportunity to save the day. If the pilot detects that the engine power has gone, he has a brief moment to push the collective down fast. This reverses the angle of the rotors. This means the helicopter will go down but the air now rises through the rotor disc and it operates like a sycamore seed. It can do this indefinitely all the way to the ground and, as a wonderful bonus, the pilot can control it left and right as it is doing so. At around 25-35 feet, the pilot hauls the collective up and converts the rotational inertia in the rotor disc to lift, slowing the descent and hopefully allowing for a controlled landing. You will imagine correctly that the pilot only gets one attempt at this. The state of controlled descent without power in a helicopter is known as autorotation. There will be many videos on YouTube if you wish to see it demonstrated. I mentioned that the pilot has a brief opportunity to do the above if the engine fails. Generally, the moment is briefer if the rotors have less inherent inertia (few blades, less mass). The world's most popular helicopter, the two-seat Robinson R22 has two blades and low inertia. The pilot has about 1.5 seconds to get the collective down. Responsible R22 pilots do first and think later. A Bell Jetranger pilot has a comparatively relaxed four seconds to complete the same action. Lastly, like an aircraft taking off, there is a period of inherent danger in the take-off for a helicopter if the power fails at a critical moment. Generally, you should imagine that a helicopter needs to have some forward motion to be able to convert to autorotation. This is why most helicopter take-offs commence by lifting off the ground by 10-20 feet then lower the nose and accelerate across the ground until they have sufficient speed to climb safely. What actually happens is that they reach a speed in this horizontal acceleration called the transition speed, and this is when the rotors get more lift and could autorotate, if required. Next time you are in a helicopter in this scenario, you will feel a small shudder as the helicopter goes through the transition speed. This is a good thing. Finally, you will appreciate that if a helicopter takes off and climbs vertically, it has no autorotation options until it has reached a relatively high height above the ground. For the R22, a safe height when hovering out of ground effect is around 150 feet. Engine failure in a vertical take-off between 0-150 feet doesn't usually end well. Stay safe! -
12
Wise ordered to pay $2.5mn in US for misleading fee advertising
Best alternative please. Serious request. -
1,154
-
7
Thai man shot near penis in jealousy over karaoke bar girl - video
Caliber .22 should be enough
-
-
Popular in The Pub
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now