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Build Log
12' - 13' Rigid Airship
Hello all who read, I am building and designing a rigid airship for my school's science awards and I have decided to make a build log on this website so I can record progress and so I can ask questions without spamming posts in the forum page. So hopefully a few experienced people stick around this page to give advice along the way.
By the way, the designs in the images aren't exact. Anyways, onto the design of the Airship. I got inspired by Jack Clemen's 20' model of the USS Macon, so I based my first design off of the the USS Macon too. Which at first seems to be almost all upsides, it would be more sturdy, which most balsa zeppelins aren't, with reasonable amount of lift for micro RC, ~60g. The first picture will be of the first design I made. Anyways, the reason I am not using this design is because it was too heavy. When I did my first calculations, I used the weight of a small truss structure that I made, which was about 0.32 grams per inch. Which seemed fine then, but once I made three larger versions (24"), I weighed them, and apparently it is more like 0.45 grams per inch. Which when recalculating, was too heavy, even without electronics. My second design is still in development, but is more related to the WW1 German design than the first one is. Mainly because WW1 zeppelins were higher altitude airships, so they were very light. So in this design, instead of three keels I will have one. With no rings like in the Akron class ships. The general shape will be an imperfect tridecagon with the keel counting as the smallest side, with all the other sides being the same size. Right now I am planning for Y fins, but I might change it to the standard + shape, depending if I have lift to spare for servos. Now for me to ask for your guys' help. I am not very good at building with balsa. Right now I am using hot glue, which I will use CA glue for the final product, but I am not very exact with my placement, sometimes I need to cut and re-glue the pieces. Right now my design is hot dog shaped because I feel incapable of the teardrop shape that Zeppelins have. I have read on someone else's Zeppelin build log that he used something called CAD. Should I use this? What other options do I have? Also, If anyone could link me to how I can make gasbags out of mylar, that would be appreciated. I am trying to make cylinders, but the other post only showed how to make ellipsoids. If I can't make gasbags myself I will use latex balloons and Hi-float. Thank you for reading, (P.S. I might make this a flying aircraft carrier depending if there is enough lift ) EDIT: I have made the decision to go BIGGER. I have full access to a two car garage and at maximum I could build a 32 foot one. I will probably aim for about 18-22 though. |
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Last edited by Crayex; Aug 11, 2017 at 12:00 PM.
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My comments, for what their worth.
A 12'-13' rigid airship is a do-able plan. But keep in mind that you're really on the edge of what can be built at that size. The structure has to be incredibly light. I dare say, building this kind of structures does require a certain amount of skill and experience. Consider your building skills. A project like this will challenge the best of them. Hot glue is much too heavy for construction of anything but aircraft that have excess power to spare. CA is a much better choice. I'd check out the balsa builder forums to get a sense of what's being used to build balsa aircraft. In particular, search through the micro/indoor forums as these aircraft in particular are more sensitive to construction weight. You'll find lots of good info on micro electronics as well. Judging from your experimental trusses, you're choice of wood is very thick. Rigid airships (even the real ones) are severely limited by the construction weight of the ship itself. Your trusses need to be strong enough to support the airship and nothing more. Don't expect it to survive any knocking around, you'll have to treat it very delicately. Strong enough to fly, not strong enough to crash. There are a number of things going on here. Super light weight construction, helium containment, unconventional electronics, aerodynamic controls. Getting a handle on one of them is hard enough, pulling it all together into a working airship is another level. Maybe break it down and get some experience with the materials first. For example helium filled foil balloons from the dollar store are an economical way to get both envelope material and helium in a ready to go format. Find out how much lift you can get out of one balloon, combine multiple balloons into some kind of structure, grow your structure into something capable of carrying flight controls. Get some experience and control mechanisms worked out. Then you'll be much better prepared to work out a complete plan for an airship design. |
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Your input is greatly appreciated. I will try out your suggestion once I get my hands on some RC parts. Any other non-rigid/semi-rigid airships constructed for experience for this project will be posted here as well. So stay tuned, folks.
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Last edited by Crayex; Jul 16, 2017 at 04:17 AM.
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Crayex, I'm looking forward to seeing you give this a shot, it's most interesting. I would agree with most everything Ruzam said. The balsa sticks you have for the trusses are thicker than needed, and set the hot glue gun aside. I use either CA or testors wood cement. The wood cement gives you a bit more working time... Yes your drawings are crude, I use autocad because I have a copy and use it at work, but it's not cheap, there are "free" cad programs, I'd download one of those and use it, others here can probably recommend one. Once you've gotten able to operate the cad program making the teardrop shape is not difficult. You can scale the lengths of all the memebers off the cad model and even print patterns to cut and assemble them.
I built a 10 ft long rigid zeppelin type airship, that has not flown. The main drawback being internal cross bracing thread that requires many separate gas bags, as opposed to a single one. But from a structural standpoint the zeppelin type frame is much more rigid. All the members are 3/32" square balsa, the rest is thread (carpet thread). The whole frame, about 24" dia and 10 ft long weighs just 13 oz. I'll post a picture later, or you can see on https://www.rcgroups.com/forums/show...me#post8108917 If I were to do it again I'd probably go with a similar zepplin frame but with only 1 set of internal bracing somewhere near the middle, so still need two gas bags. Cap |
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Update time, I am going to the hobby shop soon to get some Balsa models I can practice with before I start on the large model. I am now making it 20 feet so a newby like me can have an easier time. I am probably going to mimic the Hindenburg's plans for the structure itself, because it was lighter than the ZRS-4/5. I will try to print the plans out to full scale so I can be more accurate. Also, I appreciate Cap commenting, he is one of the people that gave me the idea to start something like this.
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Hey,
we also have built quite a few flying rigid airships by now. The most demanding was a very small almost scale model of the LZ 120 Bodensee. You can have a look at the documentation found here: http://windreiter.de/wordpress/wp-co...e_20151113.pdf Good luck with your experiments, itīs an awesome feeling to see something so huge, so filigree, incredible lightweight, yet strong flying before your eyes |
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Hi Crayex, thanks for the kudo's but you may best save that for those who've actually flown their model, like wemperor. That's a really nice model, great job wemperor, and covering it tight so there are no internal gas bags makes a lot of sense, duh, why didn't I do that. I guess I really didn't like the idea of covering the structure. Plus I had the servos inside with the pull pull connections to the rudder and elevator etc, but that can be solved.
20 feet! that's huge, you must have a large garage or shed to build it in. Will take a lot of helium or hydrogen to fill, which do you plan to use? I have cad dwgs of what I built, not that you should use them but I can scale them up to 20' length and send you pdfs if you want. You'll need larger than 3/32" sq balsa for it though, probably at least 3/16" sq, probably 1/4", maybe use spruce if you have the $'s and use gussets. I attached pdf of side view. If you scaled it up to 20' it would be 40" diameter. The braced rings would be 30" on center with 2 intermediate infill frames, 10" on center. Note that the one I built is 13 sided, the thirteenth side being the bottom and forming the bottom side of the triangular keel truss, like the some of the actual zeps had. That adds quite a bit of extra work, but it has a purpose. Your unsupported panel size would be around 10"x10" so your covering would need be a bit heavier than what wemperor used, but at that size your weight problems should not be too bad. You'll never find enough sticks at your hobby store, unless you warn them to order an extra thousand feet for you. You'll need a bit heavier cord than carpet thread too. And you may want to use epoxy rather than CA or testors wood cement, with gussets though you can probably get by without epoxy. I'd make gussets for it out of 1/32" or 1/16" plywood. Can cut 1/32" plywood with scissors, that's a plus. Hope you do this, if you do I'm sure willing to lend any advice I can regarding its construction, keep in mind though I've never flown any blimp or airship, others on the site have. It's going to be fragile in any case, could crash in a heap, or immolate like the hindenburg. Our cat jumped on my rigid and did a fair bit of damage but I repaired it. Cheers, Cap |
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Thread OP
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Okay, forgive me for being gone a while. School was not permitting me to do much with my free time for a while. Update time, I have gathered basic tools for construction. Although I am interested in a tool Jack Clemens used for his airship. It can be pictured here : http://www.rccr1957.com/hangartalk/M...0Clemens-1.pdf
If anyone knows anything about making something like the tool shown above please reply. He did not say if this was custom made, but if it was it is INGENIUS! I have found the plans I am going to use, which is here : http://www.highriskadventures.com/ai...Z130.1-200.pdf What I need to do now is find out how to print this in a big enough size. This and my plans on the gas bags. I have been unsuccessfully experimenting with balloon foil and a heating iron designed for model aircrafts. I believe this is due to how cheap the foil was. Planning on ordering rolls from here : http://catalog.cshyde.com/viewitems/...ester-pet-film If anyone knows how to make gas cells shaped like in real life, please reply. Thoughts? Thanks for reading. |
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Crayex, some things you should know which might save you some money:
DuPont 'mylar' is not balloon foil material, it cannot be heat welded. Rather it must be glued, see my thread 'making mylar envelopes' in this forum. Gluing is difficult, you be better advised to use balloon foil and heat weld it. The reason you failed with a heat iron for shrinking covering film is probably that it wasn't hot enough; welding requires higher temp. You need a temperature controlled soldering iron. Best of luck |
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