Hole in the Back and Shake Rattle and Role

Hi All

Got back from New York safe and sound on VS45/46, on the way out had the V:Port V Nice the quiz is very addictive, though the SMS didn't work! Any how got a jumbo on the way out and i was interested to know what is the large whole at the back under the tail, It looks like an Exhaust but for what? The Engines are ducted to it so whats it for!

Secondly on the way home we had an A340, looked very new but on taxi at JFK the thing really banged and shook to the point that people were oohhing and arrring. Then on Take off really rattled. In the air seemed ok, But my question is, is the plane made this way to allow for a smoother flight or do you think it was growing pains?

Excellent flights though will definatly go V again.

Cheers All

Danny

The 340s do seem to rattle a bit on taxi and take off and sometimes get thrown around in the air but they are very quite.I like the 747-400 over everything else in the air at this time.
I would asume The hole at the back of the jumbo(could be wrong)is an exhaust for onboard generators.

I take it that it is for the Auxilliary Power Unit (APU) which allows the aircraft to use power from its own source instead of having to be hooked up to a exterior source

Yeah we had V-Big on the way out (747-400) Was Very smooth and felt very solid.

The Exhaust thingy must be something else as when the A340 was sitting at the gate with the engines off, heat haze was still coming out of the hole in the back.

Confused me! LOL

Danny

Most larger passenger aircraft have the small exhaust at the back - sometimes it's right at the back (most Boeings, Airbuses, Embraers), on others it's tucked next to the tail (Fokker 70/100, BAe146/AvroRJ, DC9/MD80/MD90).

In all cases, it is the exhaust for the APU (the Auxiliary Power Unit).

This is a small turbine engine that provides power for the aircraft when the main engines are shutdown, provides compressed air to the cabin air system when on the ground, and is used to start the main engines.

If an aircraft is parked for any extended period, the APU is shutdown (saves fuel and wear and tear), and an external power supply is connected, through a connector near the nosewheel. An external air conditioner may also be attached using large hoses which connect to the underside of the aircraft. These are very common at US airports, and are either mobile units on the back of a small truck, or fixed to the underside of the jetway.

Cheers,
Mike

Hi

Cheers for that excellent explaination. Cleared up all i needed to know.

Cheers

Danny

Hey,

Being a VA staffer i guess i "should" be able to answer your question.....

Alana was correct this exhaust that you see is in fact the exhaust of the APU (Auxiliary Power Unit). Used mainly on the ground to provide electrical power and to assist with starting the engines.
Simply, it is a mini gas turbine engine that is only really used on the ground, it can however be used in flight but this isnt very common.

With regard to the Airbus/Boeing matter, having flown both i know exactly what you mean...there isnt any real answer. Both are v good aircraft, but obviously one being american and the other european leads to differing techniques used in the manufacture of the aircraft, resulting in the a/c feeling and sounding different

Hope this Helps.

Coming home from KL once my wife and I went up to the cockpit. The pilot chatted for about 1 1/2hrs. He actually seemed quite sad to see us go ! Suppose they like company as well.
Anyway, we were on a 747 and he started to show us all the instruments/controls. He then actually reduced the power in the engines and move the plane a little to show how the readings change. I mentioned loading ie what would happen if all the luggage and passengers were on one side - would the plane tip. Obviously not and he said how 747's can fly on 2 engines - 1 and you'll want to land quickly ! However, he said airbuses were notorious in their balancing and he hated flying them just in case someone had loaded it wrong. The rattling also didn't help. I'm no techie so there could a certain amount of hyperbole in his story - a boastful captain, surely not..........

yeh the 343 does tend to rattle a bit although the 763 also tends to do the same. It will also depend on what condition the taxiway/runway is in. And if you think the 343 rattles try an ATR 72! Wow!

And back in 97 flew on one of air atlantas 742's that was being wet leased to Airtours! The plane rattled so much that the liferaft above the emergency exit fell from the celling mid flight and the locker had to be taped back up! Luckily this air atlanta a/c isnt now in VS colours!

Vrocking... Surely you mean "flown in" rather than actually "flown" seeing as you're an engineer? [}:)]