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787 Height  
User currently offlineORDFan From United States of America, joined Jun 2007, 289 posts, RR: 0
Posted (4 years 1 month 1 week 3 days 16 hours ago) and read 4192 times:

First off, let me preface by saying I think the 787 is a very beautiful, sleek airplane. I'm very much looking to flying on her in the future. But, since the first schematics came out a few years ago, and as was confirmed by photos of the production aircraft, I've always thought the 787 appeared to be a bit short relative to other Boeing and Airbus widebody aircraft. The landing gear struts (both nose and main) seem shorter than those on planes of similar size, and plane's belly seems to sit much closer to the ground than that of the 777 or even A330. I understand the 777 has a wider diameter engine which would necessitate it's increase in height. I was not able to find any data on the 787's height from ground to underbelly; does anyone have any such data? Would a person be able to stand upright under its belly? If not, was this lowered design done intentionally?


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Photo © Royal S King


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Photo © Tokyo Spotter


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Photo © Petr Volek



8 replies: All unread, jump to last
 
User currently offlinebohica From United States of America, joined Feb 2004, 2661 posts, RR: 0
Reply 1, posted (4 years 1 month 1 week 3 days 16 hours ago) and read 4062 times:

It's 5' 9" from the ground to the bottom of the fuselage. That means I can walk under it without banging my head.  http://www.boeing.com/commercial/airports/acaps/787sec2.pdf

This has about every dimension you need to know.

EDIT: The 767 height ranges from 7' 5" to 8' 3". I couldn't find data for the 777 but the bottom of the FWD cargo door is 9' 3" to 10' 0" off the ground so that should give you a good idea of its height.

[Edited 2010-05-31 10:10:07]

User currently offlineStitch From United States of America, joined Jul 2005, 30388 posts, RR: 84
Reply 2, posted (4 years 1 month 1 week 3 days 16 hours ago) and read 3993 times:
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The 787-8 has 1.75m of clearance from the belly to the ground.

Boeing doesn't provide that data for the 777 family, but from the bottom of the forward cargo door to the ground is between 2.81 and 3.05m on the 777-200 while on the 787-8 it averages 2.44m.

For the A330-200, ground clearance is measured at three points but at the minimum (Frame 45) it's 1.81m to 2.02m. Frame 20 seems to better match up with where Boeing measures the 787-8's ground clearance and that is 1.84m to 2.04m.

So yes, the 787 probably does sit a bit lower to the ground than the A330-200.


User currently offlinefx1816 From United States of America, joined Mar 2004, 1400 posts, RR: 4
Reply 3, posted (4 years 1 month 1 week 3 days 15 hours ago) and read 3929 times:

From what I've seen of the 788's that show up at VCV, it appears as though it's roughly the same size as a 763. Not exactly I'm sure and I don't have time to look up the dimensions to compare but I have worked with quite a few 762's and 763's and it seems that is about right.

Quoting ORDFan (Thread starter):
I've always thought the 787 appeared to be a bit short relative to other Boeing and Airbus widebody aircraft. The landing gear struts (both nose and main) seem shorter than those on planes of similar size, and plane's belly seems to sit much closer to the ground than that of the 777 or even A330.

I don't believe that the 787 is supposed to be a 777 replacement so why would it need to be higher up to reach the height of a 777 or A330??? I mean look at the 737 family, they all sit lower than the A32x family with which they compete against.

FX1816


User currently offlinespeedmarque From United Kingdom, joined Jul 2005, 684 posts, RR: 1
Reply 4, posted (4 years 1 month 1 week 3 days 15 hours ago) and read 3890 times:

ORDfan

That's it! You have hit the nail on the head for me. I was wondering why I wasn't quite sure about the 787s looks when on the ground and you have cracked it! (IMHO) it seems to sit too low.

Thank you!


User currently offlineHAL From United States of America, joined Jan 2002, 2548 posts, RR: 53
Reply 5, posted (4 years 1 month 1 week 3 days 15 hours ago) and read 3712 times:

The short answer is this: The determining factor for height is keeping the engine cowling a minimum distance from the ground. On the 787 there is more dihedral (wing angled up) than on other models, so that at the location where the engine attaches to the wing, it starts farther from the ground. Relative to the fuselage, the engines sit higher. Therefore the whole assembly can be placed lower, and still keep the engines the required distance from the ground.

For comparison, look at side views of the 787:

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Photo © Axel J.



and the 757:

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Photo © Orlando G. Rivera Rivera - SJU Aviation Photography



Notice that the engines sit much lower relative to the fuselage on the 757, so keeping those low engines off the ground is what makes the 757 look like it's on stilts. The same thing applies to all low-wing jetliners - the higher the engines, the lower the fuselage is to the ground.

HAL



One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.
User currently offlineORDFan From United States of America, joined Jun 2007, 289 posts, RR: 0
Reply 6, posted (4 years 1 month 1 week 3 days 13 hours ago) and read 3628 times:

Quoting speedmarque (Reply 4):

That's it! You have hit the nail on the head for me. I was wondering why I wasn't quite sure about the 787s looks when on the ground and you have cracked it! (IMHO) it seems to sit too low.

Glad to know I wasn't the only one thinking that!

Quoting HAL (Reply 5):
The short answer is this: The determining factor for height is keeping the engine cowling a minimum distance from the ground. On the 787 there is more dihedral (wing angled up) than on other models, so that at the location where the engine attaches to the wing, it starts farther from the ground. Relative to the fuselage, the engines sit higher. Therefore the whole assembly can be placed lower, and still keep the engines the required distance from the ground.

Excellent post, Hal. You definitely expanded on my next train of thought. It definitely appears to me that the 787 wing joins the body at a higher point than the 767 and with more of an angle (agreed with those who wrote that it is a more fair comparison).

Additionally, I might add, that the 787s nose does not curve up as much as the 767 and it seems that the flightdeck sits lower than on the 767 as well. Below are some pics for comparison


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Photo © Kenneth Low


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Photo © Enrico Pierobon SpotIT


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Photo © William T Shemley


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Photo © Matthew Hom



User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 7, posted (4 years 1 month 1 week 3 days 10 hours ago) and read 3507 times:

Quoting ORDFan (Thread starter):
I've always thought the 787 appeared to be a bit short relative to other Boeing and Airbus widebody aircraft.

That's because it is a bit shorter than other Boeing and Airbus widebody aircraft.

Quoting ORDFan (Thread starter):
Would a person be able to stand upright under its belly?

Most people can. If you're above 6' you may want to duck just a little.

Quoting ORDFan (Thread starter):
If not, was this lowered design done intentionally?

I'm not really following you here...it's not like they designed and built the plane and then discovered how tall it was. They'd have known the height for a very long time. You don't make airplanes any taller than they need to be...there's no advantage to the height, and it costs you in weight. Once you've chosen basic configuration (pylon design and mounting point, wing loft, nacelle diameter, etc.) the height falls out of that.

Quoting HAL (Reply 5):
On the 787 there is more dihedral (wing angled up) than on other models, so that at the location where the engine attaches to the wing, it starts farther from the ground.

Also, the pylon goes "uphill" more than most other models.

Tom.


User currently onlineMax Q From United States of America, joined May 2001, 4311 posts, RR: 19
Reply 8, posted (4 years 1 month 4 days 4 hours ago) and read 2993 times:

You are completely correct, it does look like it sits too low, it does not look 'right'


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