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In 1784, Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, the first recorded means of propulsion carried aloft. In 1785, he crossed the English Channel in a balloon equipped with flapping wings for propulsion and a birdlike tail for steering.[49] ~ Wikipedia

I was curious how much utility wings and a tail could have for a balloon, after reading that account. I expect the level of propulsion was quite small... but could it still be enough to be useful? Perhaps for landings, or trying to change between air currents? I'm not sure if he moved fast enough that the tail would be useful for steering?

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Searching for images of this powered balloon, I found this one, which happens to have a description in french that says :

A. Aerostatic globe 27 feet in diameter filled with flammable air and attached to circle a, b,

B. Parasol of 18(?) feet in diameter whose branches are held to the axis or handle by the strings. d.d.d.and are spread out from the circle a.b. to gather all in c. Note, it should only be used to support the machine in the air in case of accident to the globe in order to avoid a violent fall.

C. Vessel carrying the passengers suspended and fixed to the axis or handle of the parasol.

D.and E. Fins or wings moved alternately by the passengers by means of the branches e.f. fixed to the axis or axle of the wings, those marked E are open and pull on the air to make the the vessel to move forward at will, and those marked D are closed since they act in the opposite direction.

F. Rudder

G. Fins or wings seen from the front, the upper one is closed and the lower one is open. Note: The strings g. are used to prevent the wings from opening too much or tipping over and hold them by means of the support h. as the parasol is held by the strings d.d.d.d.

blanchard

(source)

In 1784 metric system was not there yet. According to wikipedia, at the time in France one foot was 326,569mm from 1668 to 1799.

Therefore, the balloon is 8,77m in diameter, 353m3 in volume. If the gaz is hydrogen, it can lift 423kg. Its frontal area (disc projection) is 60,4m2. Coefficient of drag of a sphere 0,4

Let's assume the rudder starts being effective at ~10km/h, or 3m/s The force needed to move this sphere at a constant 10km/h fighting against its drag is 1,365kN

The propelling method using reciprocating folding leaves-look alike, named D. and E. do not seem efficient compared to a propeller, yet it still moves some mass of air.

Any propulsion method that achieves to move a mass of air in the desired direction is effective, which does not mean it is useful.

For instance this powered flying vessel may very well propel itself and navigate using its fins, and rudder, inside a large hangar.

However if it flies outside it will have almost no authority against the slightest breeze.

---- somehow I'd love to see a test of the 18ft diameter parasol safety device ----

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  • $\begingroup$ Thank you for the fine information and great answer. 1.365kN sounds like a lot. $\endgroup$
    – Nail
    Commented Aug 16, 2022 at 9:23
  • $\begingroup$ That 1.3kN pushing 3 meters per second works out around 4000 Watts . Peak human power is about 1000 watts and stead state 400 watts. So even with ideal propulsion (not those wings) you'd need to fit at least 10 people to get much movement, and you'd still be going pretty much where the wind took you. $\endgroup$ Commented Aug 16, 2022 at 10:39
  • $\begingroup$ @GremlinWranger Hmm... that sadly made it very hard to control balloons even a little. It would be very interesting if there was a way to jump between air-currents. $\endgroup$
    – Nail
    Commented Aug 16, 2022 at 13:02
  • $\begingroup$ @nail Remember that the air in a region at a given altitude goes in one direction so balloons can already pick a direction by changing height. Issue is that a given time may only offer a limited range of directions, and you may have to pass through layers with 'bad' directions to get to the one you want, impacting any attempt at precision. $\endgroup$ Commented Aug 17, 2022 at 13:05

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