Start with my plans set. It identifies everything you will need. I don't do kits so ...if you are starting with nothing, the whole thing will cost somewhere on the order of $600-800 dollars. If you can find a radio at a garage sale or find one used, you are looking for one with four channels. Any scrounging you can do will certainly lower the price considerably. If you already have a radio, drop the price by at least 200-300 dollars. The cost drivers in LTA are the servos, motors and speed controllers. They MUST be lightweight if you are building a small dirigible. Lightweight servos demand a premium, but fortunately, they are getting cheaper. Don't worry about the reliability so much. You can lose an axis of control on a dirigible and still get home.
It will take about 2-3 weeks of evening work to finish. There is really nothing complicated about it, it just takes time. It helps if you have another person around when you are covering it. The gondola takes an evening, the fins take an evening. The formers can be done in a couple evenings. The bulkheads front and rear take an evening and final assembly takes a couple few evenings. Covering takes several days. Leak testing also takes a couple days. Fortunately ZAP glue dries quickly.
This takes about a day the first time you do it. Plan on a Saturday or Sunday to do it the first time. Subsequent times take about 4 hours. Once topped off, it can be flown on consecutive days after only a few minutes of filling. As mentioned before, you can lose an axis of control and still get down. You can even run the batteries flat and get back if you have ballasted correctly.
Order the plans package if you are even considering doing your own design. It will be well worth it. The plans package goes into construction planning in detail. If all your planning says it will fly, it will fly, but you need some real numbers to help you calculate how light everything must be. Some things that appear to be a good idea (like scaling down the original drawings of some airship) just don't pan out in the real world. If you are that serious, give me a call and we will discuss the ideas you have. If you follow the plans to the letter, it will fly, and you will have wide margins for payload and ballast.
Now you have a rare treat on your hands. I love to let people fly
mine. It is almost comical to let them get really out of control to the
point of an imminent crash, then LET THEM CRASH. It's really hard to do
any damage to them when they are pumped up. They are easy to master
and they motor by so purposefully, it is still amazing, even for me.
You can dart among the rafters and stop
in midair, holding station, then resume flight. Then come in for some
approaches to a mast just like the real thing. You can even practice
picking things up off the ground with a small hook or magnet. You can
walk next to it as it is flying. You will find most people just stare
in awe. This is the same stare that greeted the great airships I'm
sure. Kids get all excited and follow it around. You can talk to
people when you are flying it and look them in the eye. It is not a
demanding task to fly.
I've had quite a bit of interest from schools wanting an aviation science project. First if you do not intend to challenge your students, buy someone elses airplane kit and assemble it. If however you are a true teacher (I use the word with all the respect it deserves) then try the dirigible. It will expose them to design planning, materials research and sourcing, the real world of engineering compromise and teamwork. Divide up the tasks into powerplants, structures, engineering, and flight test. Even if they fail (I did - more than once), they will will learn a valuable lesson (PERSERVERE!). A lesson they can carry to successful careers. It's fun and everyone can fly it when it's finished, not just the few that might have some special qualifications. The next class can do a performance analysis.