Lifting James' Giant Peach Would Have Required Way More Seagulls Than Roald Dahl Said

Physicists calculate how many newtons of force would be needed to carry the peach across the Atlantic.

By Rebecca Boyle Posted 01.08.2013 at 4:21 pm 6 Comments

James and the Giant Peach Illustration by Nancy Ekholm Burkert

Ah, physics: Taking the world’s greatest mysteries and turning them into cold, hard facts. Even the mysteries in beloved children’s stories. A group of physics students from Leicester University in the UK has subjected James and the Giant Peach, a classic tale by Roald Dahl, to aerodynamic modeling.

In the story, orphaned James seeks refuge with a bunch of anthropomorphized insects inside a huge stone fruit, which is then toted across the Atlantic Ocean by a flock of seagulls. Dahl said it would take 501 birds to do the job: “I shall simply go on hooking them up to the stem until we have enough to lift us. They'll be bound to lift us in the end,” James explains. In fact, 2,425,907 seagulls would actually be needed, according to the students' research paper.

Emily Jane Watkinson, Maria-Theresia Walach, Daniel Staab and Zach Rogerson calculated the mass of the peach, which Dahl says is “as tall and wide, in fact, as a small house,” estimating that it would have a radius of 6 meters. They examined footage from the 1996 Disney movie adaptation and calculated its height at 5.7 meters. Performing several other calculations, they determine it would require 4,890,579 newtons of force to lift it. “This greatly exceeds the carrying capacity of 501 Common Gulls,” the students write.

To determine this, they modeled the seagulls as airfoils, which you can think of basically like an airplane wing. These curved shapes create the force known as lift. A common gull can provide 2.02 N of lift, the students write. “For a peach of the dimensions calculated, it would not be possible to fly such a heavy object with the assistance of such a diminutive number of birds,” they conclude.

Their course leader, Mervyn Roy, said the exercise prepares his students for a career in scientific publishing. To be a research physicist in industry or academia, “you need to show some imagination,” he explained.

As The Guardian put it, scientists still have not found the formula for the magic potion that caused James’ peach to grow quite so large. Nor have they figured out how Matilda moved objects with the power of her mind.

[via AlphaGalileo]

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6 Comments

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schmidticus

01/08/13 at 4:53 pm

No, Roald Dahl was right. They forgot to take into account the fact that talking animals warp space-time to reduce the mass of objects around them. I'm not sure how they missed that obvious fact. ;-)

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kook916

01/08/13 at 10:42 pm

The peach was also partly hollowed out...

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Robot

01/09/13 at 8:04 am

Considering the quantity of Gulls, that peach should be covered completely like icing on a cake with bird do do, lol!

And considering the people on and inside the peach and the length of time of their journey, they should all die from some kind of strange virus.

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Robot

01/09/13 at 8:28 am

Side note, we are all nitpicking..... sad sigh.

I actually like the story! ;)

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bgdavison

01/09/13 at 2:11 pm

The next thing they'll say is that the snozberries cannot possibly taste like snozberries!

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jameshay

01/10/13 at 9:32 pm

Great extrapolation about the giant peach, but what's with all the significant digits? They're only estimating the peach to 5.7 and the interior is a complete guess (and they didn't even count the weight of the passengers) but they give a gull count to seven digits.