Hot Air

September 11, 2009 11:32 PM

Did the Montgolfier brothers' hot air balloon have a fire burning in it?

I'm just watching episode 4 of John Adams, the HBO miniseries, which depicts Adams and others watching a demonstration of the Montgolfier brothers' hot air balloon. It seems like a very faithful recreation and not like a special effect at all.
I found it interesting that the fire is not contained within the balloon. The balloon appears to rise from a bonfire at its base and lift upward, but I couldn't see a fire within the balloon itself.
According to the web, the Montgolfiers' first test flights reached thousands of feet of altitude and several miles' distance... Did they really achieve this just from a fire on the ground?
Or maybe it's just that the balloon in the show is a helium balloon?

posted by Silky Slim to Science & Nature (5 answers total)

http://en.wikipedia.org/wiki/Montgolfier_brothers

On 21 November 1783 the first free flight by humans was made by Pilâtre, together with an army officer, the marquis d'Arlandes. The flight began from the grounds of the Château de la Muette (close to the Bois de Boulogne (park)) in the western outskirts of Paris. They flew aloft about 3,000 feet (910 m) above Paris for a distance of nine kilometres. After 25 minutes the machine landed between the windmills, outside the city ramparts, on the Butte-aux-Cailles. Enough fuel remained on board at the end of the flight to have allowed the balloon to fly four to five times as far. However, burning embers from the fire were scorching the balloon fabric and had to be daubed out with sponges. As it appeared it could destroy the balloon, Pilâtre took off his coat to stop the fire.

posted by Jimmy Havok at 11:42 PM on September 11, 2009

Response by poster: I noticed that passage, but it's hardly a definitive answer.
posted by Silky Slim at 11:59 PM on September 11, 2009

Best answer: From here: Link

"...when they fed the fire under their sack of hot air with chopped straw they rose to the elevation of five hundred feet. Safely across the river they dampened the fire with a sponge and made a gentle descent in Paris."

and a direct quote from Benjamin Franklin:

"Its bottom was open and in the middle of the opening was fixed a kind of basket grate, in which faggots and sheaves of straw were burnt. The air, rarefied in passing through this flame, rose in the balloon, swelled out its sides, and filled it."
posted by empyrean at 1:13 AM on September 12, 2009

Response by poster: Thanks!
posted by Silky Slim at 1:25 AM on September 12, 2009

From a letter by Benjamin Franklin (who was there) to Sir Joseph Banks, written the same day as the flight:

This [deletions] /Balloon was larger than that which/ went up from Versailles, & carried the Sheep, &c. Its Bottom was open, and in the middle of the Opening was fix’d a kind of Basket Grate in which Faggots and /Sheaves of/ Straw were burnt. The [deletion] Air rarified in passing thro’ this Flame rose in the Balloon, swell’d out its Sides & fill’d it.

The [numeral obscured] Persons who were plac’d in the Gallery /had an/ /made of Wicker, and attach’d to/ the Outside /near the Bottom,/ had each of them a Post thro’ which they could pass Sheaves of Straw into the Grate to keep up the Flame, & thereby keep the Balloon full. When it went over our Heads, we could see the Fire which was very considerable. /When/ /As/ the Flame slackens, the rarified Air cools & condenses, the Bulk of the Balloon diminishes and it begins to descend. If those in the Gallery see it likely to descend in an improper Place they can, by throwing on more Straw, & renewing the Flame, make it rise again, and the Wind carries it farther. –

(transcription as found on the web)

There's supposed to be more detailed accounts in later letters, but the above is clear enough.
posted by effbot at 1:28 AM on September 12, 2009 [1 favorite]