They all look the same!

Discussion on Specific Aircraft Types. Close up photos particularly welcome. Please keep ON TOPIC :)

Re: They all look the same!

Postby OVERLORD_CHRIS » Sat Dec 19, 2009 9:15 am

What? That just looks like a longer 737 with four small engines instead of two big ones. ;)

What you want is this: http://www.nasa.gov/centers/langley/ima ... -81-01.jpg

That's different.
Problem with that design, is every time it banks, one side where passengers will be sitting will become weightless, while the other side of the plane will be subjected to G force. So only in level flight does every one across the plane have even gravity like a normal plane. They are still working on a way around that last I herd.



Having the engines half way out along the wings make it fairly inefficient if one fails. Having them close to the centreline of the aeroplane, such as a DC-9, VC10, BAC 1-11 & 727, means it has a lot less of an effect should you lose an engine. In a 4 jet in the configuration of the A340, 747 and 707 type, lose two on one side, and compared to say the VC10/IL62, life could be very interesting, and lead to a very aching leg! :)
This fact has yet to stop any 4 engine plane, let alone a twin engine plane. On September 11th when all flight got ground a watched a C-5B land with #1 & #2 motors flamed out, only had the right side, and it made a perfect landing like all were still working, they just landed long since only the reverser's on the one side worked. As long as they have a rudder you should be fine...unless you fly the B-2A, in witch case there are so many other flight surfaces that the Flight Control Computer(FCC) will just take care of every thing any way, just like any other modern plane with FCC's


If they figure out a way to make inertia dampeners, and a way to properly pressurize odd shapes, that will be when we get to see really cool designs be implemented.   
Image
User avatar
OVERLORD_CHRIS
Major
Major
 
Posts: 1136
Joined: Fri Aug 17, 2007 10:56 am
Location: Chalreston SC

Re: They all look the same!

Postby C » Sat Dec 19, 2009 10:48 am

Having the engines half way out along the wings make it fairly inefficient if one fails. Having them close to the centreline of the aeroplane, such as a DC-9, VC10, BAC 1-11 & 727, means it has a lot less of an effect should you lose an engine. In a 4 jet in the configuration of the A340, 747 and 707 type, lose two on one side, and compared to say the VC10/IL62, life could be very interesting, and lead to a very aching leg! :)
This fact has yet to stop any 4 engine plane, let alone a twin engine plane. On September 11th when all flight got ground a watched a C-5B land with #1 & #2 motors flamed out, only had the right side, and it made a perfect landing like all were still working, they just landed long since only the reverser's on the one side worked.


That was landing, which is quite a different kettle of fish to take off. Having chatted to some USN 707-frame drivers last year in the desert, their biggest fear was losing two on take-off. Not guaranteed to ruin your day, but certainly going to make it more difficult.

As for the initial part of your reply, I guarantee that at some point, it has.
User avatar
C
Colonel
Colonel
 
Posts: 11977
Joined: Mon May 19, 2003 1:04 pm
Location: Earth

Re: They all look the same!

Postby specter177 » Sat Dec 19, 2009 11:55 am

That's the difference between the "cool" planes of yesteryear and the "boring" planes today. The new planes engines are very reliable. The chance of one flaming out on takeoff are very low.
ImageImage
User avatar
specter177
Major
Major
 
Posts: 1369
Joined: Sat Sep 24, 2005 2:33 pm
Location: KDAY

Re: They all look the same!

Postby Slotback » Sat Dec 19, 2009 12:30 pm

On 22 September 1995, a U.S. Air Force E-3 Sentry (Callsign Yukla 27, serial number 77-0354), crashed shortly after take off from Elmendorf AFB, AK. The plane lost power to both port side engines after these engines ingested several Canada Geese during takeoff. The aircraft went down in a heavily wooded area [21] about two miles northeast of the runway, killing all 24 crew members on board.[22][23]

http://en.wikipedia.org/wiki/E-3_Sentry


Never heard any such case of a modern passenger airliner going down due to the failure of both engines on one side. Airliners have to be able to handle an engine failure at V1 to get certified.

Also, tail mounted airliners always have T-tails, which can make the vulnerable to ice ingestion and deep stall.
Last edited by Slotback on Sat Dec 19, 2009 1:05 pm, edited 1 time in total.
Slotback
 

Re: They all look the same!

Postby chornedsnorkack » Sat Dec 19, 2009 3:56 pm

On 22 September 1995, a U.S. Air Force E-3 Sentry (Callsign Yukla 27, serial number 77-0354), crashed shortly after take off from Elmendorf AFB, AK. The plane lost power to both port side engines after these engines ingested several Canada Geese during takeoff. The aircraft went down in a heavily wooded area [21] about two miles northeast of the runway, killing all 24 crew members on board.[22][23]

http://en.wikipedia.org/wiki/E-3_Sentry


Never heard any such case of a modern passenger airliner going down due to the failure of both engines on one side. Airliners have to be able to handle an engine failure at V1 to get certified.

Only one. It is perfectly fine for an airliner to go down due to two engines failing on takeoff - like the geese in the A320 over Hudson.

I think a 747 crashed in Holland for losing 2 engines on the same side.
[quote]
Also, tail mounted airliners always have T-tails, which can make the vulnerable to ice ingestion and deep stall.
chornedsnorkack
1st Lieutenant
1st Lieutenant
 
Posts: 381
Joined: Wed Mar 08, 2006 4:35 am

Re: They all look the same!

Postby ApplePie » Sat Dec 19, 2009 4:11 pm

On 22 September 1995, a U.S. Air Force E-3 Sentry (Callsign Yukla 27, serial number 77-0354), crashed shortly after take off from Elmendorf AFB, AK. The plane lost power to both port side engines after these engines ingested several Canada Geese during takeoff. The aircraft went down in a heavily wooded area [21] about two miles northeast of the runway, killing all 24 crew members on board.[22][23]

http://en.wikipedia.org/wiki/E-3_Sentry


Never heard any such case of a modern passenger airliner going down due to the failure of both engines on one side. Airliners have to be able to handle an engine failure at V1 to get certified.

Only one. It is perfectly fine for an airliner to go down due to two engines failing on takeoff - like the geese in the A320 over Hudson.

I'm not sure if that's the best comparison. The E-3 NNNG was talking about lost thrust for half of its engines (2 out of 4), the A320 lost thrust for ALL of its engines (2 out of 2).
[center][url=http://www.mysimshots.net/photosearch.php?icao=&id=&airport=&aircraft=&country=&airline=&photographer=ApplePie&flightsim=&viewtype=&remarks=&page=&date=&order=views+desc][img]http://www.simviati
User avatar
ApplePie
Major
Major
 
Posts: 2047
Joined: Fri Jul 24, 2009 1:42 pm
Location: North Carolina, USA

Re: They all look the same!

Postby C » Sat Dec 19, 2009 5:45 pm

Either way, all other factors aside, with the engines on the fuselage, you get less of an asymmetric issue.
User avatar
C
Colonel
Colonel
 
Posts: 11977
Joined: Mon May 19, 2003 1:04 pm
Location: Earth

Re: They all look the same!

Postby Slotback » Sat Dec 19, 2009 11:24 pm

Only one. It is perfectly fine for an airliner to go down due to two engines failing on takeoff - like the geese in the A320 over Hudson.

I meant both engines on one side. ;)

I think a 747 crashed in Holland for losing 2 engines on the same side.

Engine pylons on modern aircraft are designed to shear when excessive loads are placed on them. With El Al Flight 1862, the fuse pins were fatigued, so the engines broke off improperly all by themselves, and damaged the wing in the process. Wing stalled & plane crashed. That could be a disadvantage of wing mounted engines.... although I would consider it a disadvantage of an inadequate engine pylon structure. ;)

CRJ? ERJ?

Unless you count modernized (or copied) older aircraft, the ERJ, CRJ, & Tu-334 are the only airliners with tail-mounted engines that are still in production. All are regional aircraft, that are at or less than 100 seats. Maybe we'll see this configuration reappear with open-rotor engines in the future. However, for larger aircraft, I don't think there is any doubt that wing-mounted engines are better as shown with the 767, 777, 787, A330, A340, A350, A380, and the newer Bombardier and Mitsubishi regional jets. There has never been a widebody aircraft with tail-mounted engines, point is, there are reasons for this.
Last edited by Slotback on Sun Dec 20, 2009 2:39 am, edited 1 time in total.
Slotback
 

Re: They all look the same!

Postby DaveSims » Sun Dec 20, 2009 12:55 am

There is a reason for that.  If you took the engines on the 777 and tried to mount them on the tail, you'd have a heck of a CG problem. 
User avatar
DaveSims
Major
Major
 
Posts: 2350
Joined: Sat Mar 02, 2002 2:59 am
Location: Clear Lake, Iowa

Re: They all look the same!

Postby chornedsnorkack » Sun Dec 20, 2009 3:22 am

There has never been a widebody aircraft with tail-mounted engines, point is, there are reasons for this.


True. BAC 3-11 was not rolled out.

How does a BAC 3-11 simulator handle its CoG?

And how does the performance of a BAC 3-11 compete against Airbus 300?

Suppose that you were to build a suitably stretched BAC (the fuselage is wider than that of A300, something like DC-10 size, and close to 777). So BAC, say, 6-11, with a suitably bigger wing and a pair of Trent 8115 engines.

How will the CoG behave, and how will the performance compare against 777?
chornedsnorkack
1st Lieutenant
1st Lieutenant
 
Posts: 381
Joined: Wed Mar 08, 2006 4:35 am

Re: They all look the same!

Postby C » Sun Dec 20, 2009 3:43 am

[quote]There is a reason for that.
Last edited by C on Sun Dec 20, 2009 3:49 am, edited 1 time in total.
User avatar
C
Colonel
Colonel
 
Posts: 11977
Joined: Mon May 19, 2003 1:04 pm
Location: Earth

Re: They all look the same!

Postby expat » Sun Dec 20, 2009 8:10 am

There has never been a widebody aircraft with tail-mounted engines, point is, there are reasons for this.


And how does the performance of a BAC 3-11 compete against Airbus 300?


As pointed out, it was never built so the question is mute :-?

Matt
"A bit of a pickle" - British translation: A catastrophically bad situation with potentially fatal consequences.

PETA Image People Eating Tasty Animals.

B1 (Cat C) licenced engineer, Boeing 737NG 600/700/800/900 Airbus A318/19/20/21 and Dash8 Q-400
1. Captain, if the problem is not entered into the technical logbook.........then the aircraft does not have a problem.
2. And, if you have time to write the fault on a napkin and attach to it to the yoke.........you have time to write it in the tech log....see point 1.
User avatar
expat
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 8679
Joined: Tue Apr 19, 2005 3:06 am
Location: Deep behind enemy lines....

Re: They all look the same!

Postby DaveSims » Sun Dec 20, 2009 9:49 am

[quote][quote]There is a reason for that.
User avatar
DaveSims
Major
Major
 
Posts: 2350
Joined: Sat Mar 02, 2002 2:59 am
Location: Clear Lake, Iowa

Re: They all look the same!

Postby Slotback » Sun Dec 20, 2009 10:51 am

Wouldn't that mean the elevator is less effective? Shorter distance means less torque... or torque = distance*force. For this reason, short variants of an aircraft usually have larger vertical stabs, while longer variants of the same aircraft have smaller vertical stabs.

e.g.

tail on the A318 is 12.56 metres (41 ft 2 in) high.
tail on A319/20/21 is 11.76 m (38 ft 7 in) high.

It can be seen on the F-35. The horizontal stabilizer is very close to the landing gear (i.e. turning point), so you can really see the horizontal stab digging in on rotation.

http://www.bidlink.net/images/F35.jpg
Last edited by Slotback on Sun Dec 20, 2009 11:23 am, edited 1 time in total.
Slotback
 

Re: They all look the same!

Postby Ivan » Sat Dec 26, 2009 9:09 am

Its not the elevator, its the yaw stability of the shorter fuselage that messes up the flight character of those very short machines.

747SPs also have a higher tail.

And most fighter planes operate on stall edge on takeoff, thats why they fly around with absurd elevator angles. those almost-flat stabilizers arent that helpful either
Russian planes: IL-76 (all standard length ones),  Tu-154 and Il-62, Tu-134 and [url=http://an24.uw.hu/]An-24RV[/ur
Ivan
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 5805
Joined: Sun Apr 13, 2003 8:18 am
Location: The netherlands

PreviousNext

Return to Specific Aircraft Types

Who is online

Users browsing this forum: No registered users and 102 guests