AirTalk.org Aviation discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Homebuilt hot-air airships          AirTalk.org Forum Index -> Hot air, gas balloons and airships View previous topic :: View next topic   Author Message Jim Logajan Guest Posted: Wed Jul 19, 2006 6:10 am    Post subject: Homebuilt hot-air airships One of the desirable mission requirements I've wanted in an aircraft is the ability to do serious sightseeing by allowing me to pause it in flight and gaze at things. The problem with fixed-wing aircraft is that you can't stop or sometimes even slow down enough to get a good long gander at things. Only helicopters, airships, and (to a lesser extent because you can't direct them much) balloons have the desired capability. So about a year or so ago I began looking into designing and building a homebuilt hot-air airship that required little or no ground crew to launch and land. While doing research into airships, I came across the Skyacht Aircraft company: http://www.personalblimp.com/ Late last year I had an e-mail exchange with the Dan Nachbar, the inventor of this particular design, and at that time he wished to maintain a low profile. I see now he will be giving a presentation at Oshkosh, so I assume he is no longer trying to keep such a low profile. Looks like he still has some ways to go, but if my own (top secret! ) airship idea never get off the ground I will definitely be looking into getting one of his creations once it becomes generally available. (Other existing hot-air airships seem to require too much ground support and because they rely on pressurization, are a little too performance limited for my taste.) So - has anyone reading these groups ever built or considered building a homebuilt gas or thermal airship? Back to top Guest Posted: Wed Jul 19, 2006 6:10 am    Post subject: Re: Homebuilt hot-air airships Jim Logajan wrote: Quote: One of the desirable mission requirements I've wanted in an aircraft is the ability to do serious sightseeing by allowing me to pause it in flight and gaze at things. The problem with fixed-wing aircraft is that you can't stop or sometimes even slow down enough to get a good long gander at things. Only helicopters, airships, and (to a lesser extent because you can't direct them much) balloons have the desired capability. So about a year or so ago I began looking into designing and building a homebuilt hot-air airship that required little or no ground crew to launch and land. While doing research into airships, I came across the Skyacht Aircraft company: http://www.personalblimp.com/ Late last year I had an e-mail exchange with the Dan Nachbar, the inventor of this particular design, and at that time he wished to maintain a low profile. I see now he will be giving a presentation at Oshkosh, so I assume he is no longer trying to keep such a low profile. Looks like he still has some ways to go, but if my own (top secret! ) airship idea never get off the ground I will definitely be looking into getting one of his creations once it becomes generally available. (Other existing hot-air airships seem to require too much ground support and because they rely on pressurization, are a little too performance limited for my taste.) So - has anyone reading these groups ever built or considered building a homebuilt gas or thermal airship? Dunno if he reads these newsgrousp but the comedian Gallagher built one, or had one one built for him 2 or 3 decades ago. -- FF Back to top Jim Logajan Guest Posted: Wed Jul 19, 2006 6:10 am    Post subject: Re: Homebuilt hot-air airships fredfighter (AT) spamcop (DOT) net wrote: Quote: Dunno if he reads these newsgrousp but the comedian Gallagher built one, or had one one built for him 2 or 3 decades ago. It was built for him, used helium, not hot air, and was pedal powered: http://home.teleport.com/~reedg/whitedwarf.html http://www.myairship.com/database/whitedwarf.html Much as I could use the exercise, I was thinking more along the lines of mechanical propulsion. Back to top john smith Guest Posted: Wed Jul 19, 2006 5:28 pm    Post subject: Re: Homebuilt hot-air airships Quote: While doing research into airships, I came across the Skyacht Aircraft company: http://www.personalblimp.com/ So - has anyone reading these groups ever built or considered building a homebuilt gas or thermal airship? As with most homebuilt advertising, look to see it the article has actually flown. From the photos on the above website, this one hasn't. What does that tell you? The one photo of "tethered" lift is taken at night. Again, one must ask the question, why? Back to top Jim Logajan Guest Posted: Wed Jul 19, 2006 9:28 pm    Post subject: Re: Homebuilt hot-air airships john smith <jsmith (AT) net (DOT) net> wrote: Quote: As with most homebuilt advertising, look to see it the article has actually flown. I know it hasn't flown untethered yet. The inventor had taken some effort to avoid people getting the wrong idea about the pace of progress. He went to the trouble of using HTML metatags so as to have his web site excluded from search engine results. I only found his web site rather obliquely. I only mention his site now because it appears he has finally removed those metatags and is making a presentation at Oshkosh. Quote: From the photos on the above website, this one hasn't. What does that tell you? Nothing I didn't already know. Dan Nachbar has already stated that the pace of progress is much slower than expected. Quote: The one photo of "tethered" lift is taken at night. Again, one must ask the question, why? Eh? The caption to that picture seems to explain things rather clearly: "October 28, 2005 -- Here's a shot of your intrepid adventurers piled into the cabin and making a first tethered flight. The winds died very late that day, so this picture was taken in near darkness. So while the photo quality isn't very good, the moment it captures was quite momentus. It took nearly 4 years of work to get off the ground this first time." Back to top Jim Logajan Guest Posted: Thu Jul 20, 2006 10:55 pm    Post subject: Re: Homebuilt hot-air airships Dan Nachbar of Skyacht sent the following e-mail to me in response to my posting to these groups (rec.aviation.balloon and rec.aviation.homebuilt). Please note that he refers to some attached photos he included in his e-mail, but since these are text-only groups, I am not able to include them. === Text of message from Dan Nachbar: Greetings. Somebody pointed me to the discussion of our project on the rec.aviation.homebuilt group at google. Feel free to forward this message to the group. You are correct, we are raising the profile of the project a bit. Although, this change wasn't part of our plans. Our plan was to have the ship flying before the big Oshkosh air show (next week.) But record rains here in the Northeast have delayed our work by about 3 months. So the ship won't be at Oshkosh. Unfortunately, I had to sign up to give a talk there long ago -- before it was clear that the ship wouldn't be ready. So I'm with stuck with the commitment to give the talk, even without a ship to show. I guess our days of operating in "stealth mode" are about to come to an end and I expect to be met with a good bit of skepticism. And such skepticism is well placed. Most "great new aircraft ideas" have a very high hype-to-aircraft ratio. That's exactly why we've been keeping such a low profile. Most serious folks, with good reason, won't take any new idea seriously until it's off the ground. We have in fact been off the ground, albeit on a tether, a fair number of times this year. We're still tuning the longitudinal balance and load-suspension system, so the ship isn't ready for free flight testing just yet. We'll get to that point in August. I appreciate the comment about the less-than-convincing photos on the project website. I hadn't realized how far the pictures there had fallen behind our actual progress. I've attached a couple of shots that show the ship off the ground. You can see one fellow acting as ballast on a line on the nose, a pile of sandbags in the cabin, the cabin is tipped at a bit of an angle and the fact that the bottom of the ship is distinctly flatter than the top. These are the sorts of things that we are working on before we can start free flights. I'll be updating the website photos soon. Regards, Dan Nachbar Back to top john smith Guest Posted: Thu Jul 20, 2006 11:36 pm    Post subject: Re: Homebuilt hot-air airships Jim, thanks for the followup postings. I am courious as to how Dan plans to control ascent/descent? Is there going to be a ballonette inside the envelope? Back to top Jim Logajan Guest Posted: Fri Jul 21, 2006 12:28 am    Post subject: Re: Homebuilt hot-air airships john smith <jsmith (AT) net (DOT) net> wrote: Quote: Jim, thanks for the followup postings. I am courious as to how Dan plans to control ascent/descent? Is there going to be a ballonette inside the envelope? Ballonette's aren't actually used to control buoyancy; they are used to allow for lifting gas expansion as an airship rises. As an airship rises the atmospheric pressure drops of course, so either the lifting gas has to be vented (if the lifting gas container can't change volume), or the container has to expand in volume to maintain equal pressure with the atmosphere, or the container has to be strong enough to hold the large pressure differential. That last is needlessly difficult. So since most airships now use relatively expensive helium, venting is out of the question, so ballonettes are used. When using hot air, venting is a simpler solution and not as costly. Ascent and descent are almost certainly going to be controlled in the same manner that hot air balloons use: by increasing the bouyancy by applying more hot air (or dropping ballast) to ascend and venting of hot air to descend (or allowing natural cooling to take its toll). Fortunately hot air is much cheaper than helium. If you are interested in more details, I suggest you review the paper they presented at an AIAA forum: http://www.personalblimp.com/misc/atio2003.pdf Their patent, 6,793,180, can be examined at the U.S. patent office online: http://www.uspto.gov/patft/index.html Back to top Rich S. Guest Posted: Fri Jul 21, 2006 2:18 am    Post subject: Re: Homebuilt hot-air airships Some time ago I read a book about Alberto Santos Dumont and his "Personal Balloons" which he used to commute about Paris. It was altogether fascinating. http://www.earlyaviators.com/edumona.htm Rich S. Back to top Jim Logajan Guest Posted: Fri Jul 21, 2006 10:49 pm    Post subject: Re: Homebuilt hot-air airships "Rich S." <capn27kill (AT) spammers (DOT) yahoo.com.sg> wrote: Quote: Some time ago I read a book about Alberto Santos Dumont and his "Personal Balloons" which he used to commute about Paris. It was altogether fascinating. http://www.earlyaviators.com/edumona.htm In "The Giant Airships" by Douglas Botting, 1981 (ISBN 0-8094-3272-2) some of Santos-Dumont exploits are also mentioned. But it appears he eventually changed his interest from lighter-than-air, which he became disenchanted with, to heavier-than-air. From that book: "Santos continued to build airships over the next few years. The most successful of them was No. 9, a small, tubby and splendly maneuverable craft. In this runabout he performed all manner of wonderful - and impudent - things. In 1903 a correspondent for the Paris weekly L'Illustration wrote of one such incident: "I had sat down at the terrace of a cafe on the Avenue du Bois de Boulogne and was enjoying an iced orangeade. All of a sudden I was shaken with surprise on seeing an airship come right down in front of me. The guide rope coiled round the legs of my chair. The airship was just above my knees, and Monsieur Santos-Dumont got out. Whole crowds of people rushed forward and acclaimed the great Brazilian aviator. He asked me to excuse him for having startled me. He then called for an aperitif, drank it down, got on board airship again and went gliding off into space." Such displays only faintly disguised Santos' growing inner disenchantment. "To propel a dirigible balloon through the air," he was heard to remark, "is like pushing a candle through a brick wall." He had developed his airships as far as his talents and vision allowed, but they never evolved beyond their role as personal vehicles for their inventor." 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