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48

I grew up in a family hot air ballooning business, and while I haven't been involved in a few years, I can answer your question in two words: They don't! Taking Off As far as collisions go, the other answers have mostly addressed this: hot air balloons only control vertical movement, so with all the balloons experiencing the same wind, they'll move at ...


36

The perspective on that photo makes it hard to tell, but it looks like many of the balloons are still on the ground. So it's not quite as chaotic as it appears. There is no direct horizontal control. All they can do is ascend or descend to catch the preferred wind. How do they steer those away from each other to avoid mid air collisions? For the ...


35

The main disadvantage is the energy required just to get off the ground. Let's do a back-of-the-envelope calculation, comparing this to a hot air balloon. Let's heat 1m³ of air. To get equivalent lift, we need about 0.5m³ of steam. The density of air is about twice the density of steam. So, for a given amount of lift, we need to heat approximately the same ...


33

The balloon is spread out on the ground and rigged to the basket. Then, a cold air blower is used to do the initial inflation, blowing air into the envelope through the bottom aperture. This gets the balloon about 75% inflated, but still horizontal. Lastly, the burners are lit to heat the cold air already inside the canopy, expanding it and raising the ...


31

The airspeed of a hot air balloon is always... zero. So it's completely up to the bird to do the avoiding. Which shouldn't be too difficult for the bird, on account of this humongous giant brightly coloured monster thing floating in its way. Ya gotta be a pretty dumb or drunk bird to run into one.


30

The balloons just float, there is no thrust so no wake etc. If there is a constant wind, all balloons have exactly the same speed. Only local phenomena can create differences in horizontal relative distances, such as: Wind gusts and wind direction changes Wind shear Local updrafts A local difference in wind speed will accelerate first one, then the second ...


29

These are gas balloons. Instead of heating the air to reduce its density and providing the buoyancy, these balloons use helium or hydrogen which is lighter than air. Before lifting off, the balloons are kept on the ground by extra weight hanging on the basket. Usually these bags, clearly visible on the picture, are filled with sand. During the flights, the ...


27

What if the engines fail? In early airships this happened frequently, and many ships limped home on a reduced number of engines. Note that all airships were both vertically and laterally unstable. The helmsman had to continuously adjust the rudder angle to keep the ship on course. In NACA TN 204, Frank Rizzo concluded that enlarging the fins would be ...


19

I've got over 100 hours in balloons, crewed for around 200 more flights and used to work at a hot air balloon MRO. I have never noticed or heard of a bird strike or seen any damage from one. I have had multiple mid-air collisions with other balloons. Have seen a balloon with bullet holes (from someone who thought it would pop) and many other tears and rips. ...


16

Hydrogen. Helium was scarce or not available at all. The only substantial source was in the United States, which had a capacity of 24 million cubic feet (680,000 m³) in 1940. Its commercial and military needs of that time were just a quarter of this amount. If you look at this statistics of word helium production, you will notice that only from 1963 on did ...


16

According to a BBC article here, hydrogen was used, not helium.


16

That is exactly how balloons “steer” - they pick an altitude where the winds aloft are going the way the pilot wants to - assuming winds at an available altitude exist where the wind is what the pilot wants. Many balloonists use Ryan Carlton’s wind tool found here to get a good idea of local winds: http://ryancarlton.com NOAA has a website called RUC ...


11

As a balloon pilot: no we do not. We do fly regularly in classes G, D, and E and will occasionally wander into class C; but it is very frowned upon...and you better have an aircraft radio or at least call the tower to let them know you are there. Of course balloons always have right-of-way so if you see us get out of the way; we can't control where we're ...


11

To expand a bit on what @ratchetfreak said in a comment... The leading edge on that glider is not secured properly. It would need to go around the bar all the way along the leading edge of the wing, otherwise the holes would make it so the airfoil doesn't function. As it is right now, the air would hit those gaps and make the cloth flutter, which ...


11

The license required for operating a manned free balloon would be a "Lighter-than-air, Balloon" license (as opposed to a "regular" license, which is usually thought of as being for "regular" Airplanes - the kind that take off and land using runways, as opposed to lakes). Cluster balloons are, for all regulatory purposes, just "balloons" - the only difference ...


11

From the FAA's Chart Users' Guide: AeroNav Products’ charts are prepared in accordance with specifications of the Interagency Air Cartographic Committee (IACC) and are approved by representatives of the Federal Aviation Administration (FAA) and the Department of Defense (DoD). Book 2 of the IACC Specifications covers Sectionals and VFR Terminal ...


11

They use the fact that the wind veers when going up, that is, changes direction clockwise, and backs, changes direction counterclockwise, when going down. This is largely (there are a lot of other factors but this is the one we are interested in) due to the tendency of air in the atmosphere to spiral away from high pressure toward low pressure (spiraling ...


10

Unmanned balloons can indeed create a safety risk for aircraft. An aircraft could collide with the balloon itself (as described in the case that Jan Hudec posted in his comment), or with the balloon's payload (see the FAA's AIM section 7-5-4 for general comments on this). But it's important to note that unmanned balloons are (or should be) launched only ...


10

Yes, a hot air balloon would change class, if you are adding an engine and propeller to provide thrust. With powered flight comes the need to provide some form of flight control; at this point, you have an airship, albeit a thermal airship. According to the FAA's Airship Design Criteria, and much like @voretaq7's citation in another answer: An airship is ...


10

Well, a balloon already is an aircraft, specifically: A balloon is a lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater. So if you were to attach engine-driven propellers to your balloon it would no longer be a "balloon". It would start to sound a lot more like ...


10

A quick look at the FAA rules regulating hot air balloons makes it sound like, in the USA, they can enter any sort of airspace provided they can do it safely. So, theoretically, they could file a flight plan or at least alert local ATC to their activities. All of that being said, having been involved in hot air balloon operations before, I think it would ...


9

Fins, which are also known as stabilizers, increase the horizontal and vertical stability of the blimp. Without the fins the blimp would porpoise and sway, especially at low speeds. For example, if the blimp encounters an updraft, the nose would want to rise up, and the tail down. The horizontal stabilizers resist the pitching moment, the same way as the ...


9

Most likely no. RTG does not have enough power. The burner of the hot air balloon requires 2 to 4 MW of power (here) so you need at least 4 tonnes of Pu to produce that (2000,0000 / 500 = 4000 Kg), assuming 500 W per kg (0.5 W/mg). From the source, a moderate size balloon can lift few hundred kilograms at most. The true nuclear reactors provide much more ...


8

This idea is entirely plausible and has been tried before, and even successfully. But I guess you have already read through all the pages which you can find via Google. Several things are to be considered: It is really cold up there (see below), and the ascent will take long enough that you need to heat the batteries and to remove grease which will likely ...


8

In short, helium (or hydrogen) remains in the gaseous state at much, much lower temperatures than water does. In particular, helium or hydrogen will remain gaseous in pretty much any part of Earth's atmosphere. Water, on the other hand, will not naturally remain gaseous in any part of the Earth's atmosphere. On the contrary, it will freeze in most of the ...


7

An ordinary weather balloon cannot maneuver horizontally (unless an external force is applied to it) because it lacks the means to do that. It has only one purpose, to soar up to the altitude where the air pressure inside is more than outside and then burst. If you want it to steer, you can add steering servos (as mentioned in this PDF). Of course this will ...


7

The good balloonist will try to limit the vertical speed to 2 - 3 m/s (400-600 ft/minute) to make it easier for the passengers to accommodate to the pressure change and avoid ear barotrauma. This is the main factor; technically the balloon is capable of higher vertical speeds. Much depends on the temperature profile of the atmosphere over altitude. The gas ...


7

It very much depends on the balloon, but 2 metres/second in actual flight is pretty typical, while most are capable of something like 3-5 m/s ascent/descent if required. Ascent and descent speeds are normally about the same for a particular balloon, but this isn't a hard and fast rule "sport" balloons being are capable of moderately less comfortable ascent/...


6

The comment by @Andy suggesting they were Festo Air Rays almost nailed it. They were Festo Air Penguins! They can be seen maneuvering in these videos: The article http://www.robaid.com/bionics/airpenguin-flying-robot-penguins-whats-next.htm describes the mechanism: A strut to which the two ...


6

Probably not from decay heat as others have said, but ignoring the minor matter of the radiation and toxic byproducts it is clearly doable with a fission pile burning sufficiently enriched fuel. The Soviet nuclear program has had at least one criticality accident with a PU core that ended up in a sort of equilibrium between its thermal expansion and ...


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