New trend in Design of Nose of Aircraft
 

Hoping someone with experience in Aircraft design might be able to answer this question.

I have noticed a trend in aircraft design that is witnessed on three new cleansheet deigns of the past decade, the 787, A350, C-Series. And its a design feature that we haven't seen since the Commet or Caravelle. I'm specifically talking about the nose of the aircraft which continues downward from the cockpit windows rather than changing angle and jutting out.

Here are pictures of the Commet and the Caravelle
Commet
Caravelle

And here are pictures of the conventianal design of the 20th Century
B777
A330

Here are the new aircraft
B787
A350
C-series

So what is the deal? Why the sudden change back to this design for all three manufacturers? Obviously its what they have found aerodynamically most efficient, but then what on earth happened between the commet/caravelle and these newer designs? Why the switch away from this type of design and then back?

Hi Airmann,

Count the windows.

Commet and Caravelle had 4 windows each side visible (I think the centre window is visible in your Commet picture), but they were all flat plates and quite small.

As the window design improved, they get bigger (hence fewer) and more curved. In order to improve the forward visibility, they are angled inwards at the bottom. Until B787 design where the windows are so huge (only two each side) and curved they can fit the nose profile perfectly.

Embraer 170-190 was the first of recent designs to market with windshields conforming to overall nose design.

Photos: Embraer ERJ-190-200LR 195LR Aircraft Pictures | Airliners.net

Rudderrat pretty much nailed it - it's improvement in the window technology. Flight deck windows have to meet pretty demanding bird strike criteria - 35 years ago about the only way to do that with large windows was to make them flat plates. The flight deck structure and windows (what Boeing calls "Section 41) is very expensive to design and certify - as a result the 757, 767, and 777 all use the same Section 41. The design was pretty much optimized for the 767, then adapted to the 757 (that's why there is a step down onto the 757 flight deck). When the 777 came along 15 years later it was again adapted to the larger fuselage (the nose of the 777 has always had a bit of a funny profile as a result).

I wouldn't be surprised if the Airbus equivalent uses pretty much the same structure on the A330 as is used on the A300, A310, and A340 - so once again 1970's design.

For the 787, advances in technology allow big, curved, strong, windows that permitted the nose shape to be better optimized.

BTW, a little trivia - during the bird strike testing of the 767 flight deck windows, one of the birds wasn't properly aimed and 'missed high' - and went right through the aluminum skin :eek:. Given there are some pretty important electronics it that area, a doubler plate was quickly implemented into production aircraft :ok:

another trivia
 

Might be an urbin myth, but...

They were using the same test for the French TGV. The front windscreen just kept failing! So they called in some expert to surpervise the test (which failed yet again!). The expert's one and only recommendation was to use fresh chickens, not frozen ones. Next test was fine.

Yes, it's a myth.

snopes.com: Chicken Cannon

more trivia
 

When Sud designed and built the Caravelle, they saved themselves a lot of time, effort and trouble by simply buying a complete Comet nose (and presumably the drawings, and a license) from De Havilland.

Hence they don't just look similar ... they are the same.

The TV show Mythbusters did an episode on this particular myth a few years back. If I recall correctly, they didn't see a meaningful difference in damage between frozen and thawed chicken.....

Thanks all for the input

Yes the A300/310/330/340 Nose is one and the same. In fact I think the entire fuselage is the same design

So would it be right to summarize with these points:

--The "flat-nose" shape is aerodynamically more efficient and this has been known by designers since at least the construction of the Commet if not before

--In the past, in order to meet the required strength window panels had to be more or less flat due to limitations in glass technology. Therefore, in order to achieve the "flat nose" shape a greater number of smaller panels had to be installed, which resulted in a compromise in pilot visibility

--Designers of the era and subsequent eras decided that overall visibility was a higher priority than aerodynamic advantages achieved through the "flat nose", and hence the conventional pointed/stub noise design dominated aviation

--Recent advances in glass technology, has allowed manufacturers to design new aircraft with "Flat" noses while maintaining if not improving visibility vs. the conventional aircraft design

BTW, if you notice Airbus still opted with the 6 pane configuration while Boeing opted for 4. As a result the 787 needs an escape hatch as the cockpit windows cannot be opened. Airbus opted for 6 because of customer concerns that it would be too costly if a larger side pane needs replacement, although their initial design like Boeing was for 4.

Don't forget the 747. Every version has had windshields that don't affect the curve of the nose. There is a slight change to the curvature at the top of the cargo door (or where it would be on a/c without a cargo door), but that is not due to windshield limitations.

And the front windshields ARE large, curved, and heavy. 280kg each, compared to 20 and 27kg for the next two windows on each side.

And even though there are six windows, none are able to open, so there is still a crew escape hatch.

Do not forget 411A's favorite, the Lockheed TriStar, cert ca.1970. BIG curved windscreens. :eek:

The L1011 has a noticeable 'bump' right below the windscreen. It is not streamlined from the nose structure through the windshield.

RIP 411A, hope you're looking through a big curved windshield somewhere :)

280KG EACH for the 747 front windows ?


Amazing :eek:

A lot of the requirement for improved visibilty resulted from the Grand Canyon collision where a TWA Super Constellation climbed up into the underside of a United DC-7 in good weather.

The Caravelle and Viscount required a redesign of the cockpit windows to meet the new American certification requirements.

Advances in technology such as TCAS has relaxed these rules a little - hence the deletion of "eyebrow" windows from the 737 and 717.

This is the first I hear of TCAS affecting window design....

Hi ChristiaanJ,
Bien-sur, Sud-Est used the Comet 1 nose section for the early Carravelles. (Round about that time, the Comet 1s were permanently grounded, so perhaps there were plenty of them going cheap?) But the later Caravelles had a modified version, as can be seen in Airmann's link. I think the Comet Mk 3/4 may also have had deeper windshields than the Comet 1/2.

Considering the stunning price of the flat windshields (ignoring the side windows) on large airliners - with anti-misting elements inside the inner lamination, and anti-icing/anti-bird gold film inside the outer lamination - these large curved windshields must cost an absolute fortune. Perhaps the convex shape improves bird resistance?

I wonder how they avoid optical distortion, particularly if they are mounted less vertically than traditional designs. Any B787 pilots out there to comment?

ultimate nose, see X3 Stilleto.

I heard that the eyebrow windows were deleted on 737 because (get this) no need since no one does celestial nav anymore.

I like the eyebrow windows...they aid in many things.

Celestial nav in a 737? Whoever did that? Doubt it has been even used in a jurassic, much less in a classic or NG. It is simply not needed anymore as apparently it is deemed sufficient to have the much reduced viewing area and TCAS.

To be honest, i quite liked the eyebrow windows myself, especially when flying visual or circling approaches.

They were in place as the 737, in common with the 727 shared to nose section of the original 707, I'm not sure they took star shots from the 707 that often, but I know it was used.