Francis Hopkinson to Benjamin Franklin 24-May-1784
Hopkinson discusses the addition of independent propulsion apparatus to flying balloons, and suggests a type of propeller wheel.
We have been diverting ourselves with raising paper balloons by means of burnt straw, to the great astonishment of the populace. This discovery, like electricity, magnetism, and many other important phenomena, serves for amusement at first; its uses and applications will hereafter unfold themselves. There may be a mechanical means of giving the balloon a progressive motion other than what the current of wind would give it. Perhaps this as simple as any: Let the balloon be constructed of an oblong form, something like the body of a fish or of a bird, or a wherry, and let there by a large and light wheel in the stern, vertically mounted. This wheel should consist of many vanes or fans of canvas, whose planes should be considerably inclined with respect to the plane of its motion exactly like the wheel of a smoke-jack. If the navigator turns his wheel swiftly around by means of a winch, there is no doubt but it would (in calm at least), give the machine a progressive motion upon the same principle that a boat is sculled through the water.
Source
- Aeronautical Annual, vol. 1 (1895), citing The Works of Benjamin Franklin by Jared Sparks (Boston, 1838)
- "Aerostation" in Iconographic Encyclopaeda, 1889, p. 373. (Which comments "nearly seventy years elapsed before these suggests were reduced to practice.")
| Sender | Francis Hopkinson |
|---|---|
| Recipient | Benjamin Franklin |
| Date sent | 24-May-1784 |
| From location | Philadelphia |
| To location | |
| Communication type | |
| Language | English |
| Refers to flight? | 1 |
| Tech fields | LTA, balloon, propulsion, propeller |
| Length (in words) | |
| Full text available |
