Montgolfier’s balloon was inefficient, cheap, slapped together in a matter of months
I agree the balloons were cheap in the sense that they were made by a couple hobbyists. It’s not obvious to me how many people at the time had the resources to make one, though.
As for why nobody did it earlier, I suspect that textile prices were a big part of it. Without doing a very deep search, I did find a not-obviously-unreliable page with prices of things in Medieval Europe, and it looks like enough silk to make a balloon would have been very expensive. A sphere with a volume of 1060 m^3 the volume of their first manned flight) has a surface area of ~600 yard^2. That page says a yard of silk in the 15th century was 10-12 shillings, so 600 yards would be ~6000s or 300 pounds. That same site lists “Cost of feeding a knight’s or merchants household per year” as “£30-£60, up to £100″, so the silk would cost as much as feeding a household for 3-10 years.
This is, of course, very quick-and-dirty and maybe the silk on that list is very different from the silk used to make balloons (e.g. because it’s used for fancy clothes). And that’s just the price at one place and time. But given my loose understanding of the status of silk and the lengths people went to to produce and transport it, I would not find it surprising if a balloon’s worth of silk was prohibitively expensive until not long before the Montgolfiers came along.
I also wonder if there’s a scaling thing going on. The materials that make sense for smaller, proof-of-concept experiments is not the same as what makes sense for a balloon capable of lifting humans. So maybe people had been building smaller stuff with expensive/fragile things like silk and paper for a while, without realizing they could use heavier materials for a larger balloon.
I agree the balloons were cheap in the sense that they were made by a couple hobbyists. It’s not obvious to me how many people at the time had the resources to make one, though.
As for why nobody did it earlier, I suspect that textile prices were a big part of it. Without doing a very deep search, I did find a not-obviously-unreliable page with prices of things in Medieval Europe, and it looks like enough silk to make a balloon would have been very expensive. A sphere with a volume of 1060 m^3 the volume of their first manned flight) has a surface area of ~600 yard^2. That page says a yard of silk in the 15th century was 10-12 shillings, so 600 yards would be ~6000s or 300 pounds. That same site lists “Cost of feeding a knight’s or merchants household per year” as “£30-£60, up to £100″, so the silk would cost as much as feeding a household for 3-10 years.
This is, of course, very quick-and-dirty and maybe the silk on that list is very different from the silk used to make balloons (e.g. because it’s used for fancy clothes). And that’s just the price at one place and time. But given my loose understanding of the status of silk and the lengths people went to to produce and transport it, I would not find it surprising if a balloon’s worth of silk was prohibitively expensive until not long before the Montgolfiers came along.
I also wonder if there’s a scaling thing going on. The materials that make sense for smaller, proof-of-concept experiments is not the same as what makes sense for a balloon capable of lifting humans. So maybe people had been building smaller stuff with expensive/fragile things like silk and paper for a while, without realizing they could use heavier materials for a larger balloon.