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Old Mar 29, 2013, 07:01 PM
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It should work...Pyron may have something to say about but it sounds like a good idea to me. But were are going to be flying the blimp in 120 degrees Celsius, on earth?
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Old Mar 30, 2013, 12:30 PM
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if It's possible to fill up the envelope under hot air pressure and about this temperature may be possible to have an extra lift force, more than extra lift force I believe that could in part resolve the problem of hot air blimp/balloon maneuverability, with some characteristic of maneuverability of a helium blimp but filling up with hot air, what do you think??
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Old Mar 30, 2013, 12:33 PM
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with double layer, a first inside layer like lung containing hot air and second outside layer bit smaller working as thermal insulation
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Old Mar 30, 2013, 12:53 PM
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So your using heavier than air lifting gas for balloon/blimp? It should work perfectly.
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Old Apr 02, 2013, 02:36 AM
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Are you trying to design a blimp version of a Rozier balloon? Internal helium balloon located inside of an outer hot air balloon, with the hot air used to control up and down movement. This is how the record setting free balloons that made the trip across the Atlantic were designed. The hot air had a secondary benefit of heating up the helium inside and increasing its lift.

The very first Rozier balloon in 1785 (named after its inventor de Rozier) used hydrogen inside of a fire fed hot air balloon. Mr. Rozier did not survive the predictable results of such a hazardous combination.
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Old Apr 07, 2013, 05:58 AM
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Quote:
Originally Posted by pyronaught View Post
Are you trying to design a blimp version of a Rozier balloon? Internal helium balloon located inside of an outer hot air balloon, with the hot air used to control up and down movement. This is how the record setting free balloons that made the trip across the Atlantic were designed. The hot air had a secondary benefit of heating up the helium inside and increasing its lift.

The very first Rozier balloon in 1785 (named after its inventor de Rozier) used hydrogen inside of a fire fed hot air balloon. Mr. Rozier did not survive the predictable results of such a hazardous combination.
Thank for the info, I read about your blimp in another post, amazing design, colors fabrics, cutting table, burners rc!!

Rozier balloon it's very similar to the 1st idea but helium now very expensive, 2nd idea will work similar to Rozier balloon, internal hot air balloon with pressure and an outer thermal fabric balloon with pressure too, it suppose the layer of air among the two balloon would work as thermal insulation to keep internal balloon hot reducing gas consumption, I don't know very well how ripstop really would work on it, I now ripstop silicone coated is the first choice for real size hot air balloon because of the strength and light weigh of the fabric but I don't really need much strength due blimp/balloon will be RC.

I like ripstop because it's the standard but I'm not sure if is really sealed for leaks air?

even if it is silicone coated, in your post you mention about thermal blimp two problems appears the maneuverability and elevation if I correct understood, what do you think are reason of these problems?

I've seen 2 blimp/balloons from the same company Colibri and Hellies..

http://www.airstar-light.com/corpora...rships/colibri

http://www.airstar-light.com/corpora...s/elliptoplume

I wrote to camerron balloons asking them for the fabric they used because they have one very similar to Colibri from Airstar, the fabric they used is HYPERLAST 11.50 square meter double coated, very expensive perhaps could be a decisive factor, although it can be purchase a lower price direct from Dupon if I well remember

The second Elliptoplume by Airstar, filled with helium, I am very curios about what is the name of this material fabric
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Old Apr 08, 2013, 11:33 PM
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Airstar has some innovative designs, although they don't seem to have caught on commercially yet. Their hot air blimp is the standard type design, with the exception of the fabric load curtains which are generally avoided by most designers because they are immersed in heat on both sides and degrade rapidly. An all cable load system is preferred.

I've seen double wall hot air balloons that use the air gap between the two envelopes as insulation to reduce the rate of heat exchange with the outside air. These are typically used for setting duration records. I've never seen a double wall hot air blimp though, probably due to the fact that blimps have enough extra weight to deal with already and can not afford the extra load of a duplicate envelope.

In terms of an RC model, a hot air blimp is going to be the most difficult kind to attempt. I would start with a gas blimp first, they are much simpler and perform way better in a wider range of wind conditions and can run for longer durations. Trying to keep a hot air blimp at a level altitude is VERY difficult and can only be done at close range where you can visually detect if the blimp is moving up or down. Way up in the air you would never be able to control buoyancy. They are also very large by necessity due to the low lifting force of hot air combined with the heavy weight of the burners and fuel. Large size means more exposure to winds, making launch and flight difficult in all but almost a dead calm.

The Hyperlast fabric is designed to push past the roughly 300 hours of flight time standard urethane coated balloon fabric is rated for before becoming too porous to fly with. The silicon coating lasts longer than the urethane coatings, which is where the extended life comes from. Aerostar developed a diamond weave fabric which was very good also, which I believe was sold to Lindstrand when Aerostar went out of business due to litigation risks (another fine product ruined by lawyers). I don't recommend trying to use ripstop nylon for a gas blimp-- it is heavier and harder to seal than the tried and true materials mentioned on this forum. It is really only good for hot air balloons and hot air blimps, not air tight gas envelopes.
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Last edited by pyronaught; Apr 08, 2013 at 11:41 PM.
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