Quote:
Originally Posted by GregW
I suggest you contact the Experimental Aircraft Association in Oshkosh, Wisconsin. they are the brotherhood of individual aircraft designers and builders. They have local chapters all over the country and will be glad to help you learn building methods from wood and cloth to the latest fiber reinforced plastic composites. Although these folks are mostly involved with fixed wing aircraft the building techniques apply to all structures. I suggest you start with a scale model to work out structural and control systems along with researching the techniques used by the pioneers in the early 20th Century. The materials may have changed but the physics and engineering have remained the same.
Unlike some folks I would like to encourage this guy. he has set out on a difficult task and we should encourage him and wish him good luck.
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At the very least, he'll learn things about project management, goal-setting and achieving and persistence. Plus materials science and the limitations that faced many of flight-science's early explorers.
(Did you ever watch that movie about the kids who made rockets in that coal-mining town? what was it called? Rocket Man or something? Good one to watch!) I and my brother once tried, at age 16 and 18, to create a simple version of a fan-jet engine that would run on kerosene (which is exactly what Jet A is, only it gets a tad bit more refined).
It sorta spun up on it's plain bearings, whined for about 2 minutes, yellow flames out the back
(not a good sign of complete, high-pressure combustion) and then
all the rivets and soldering
(huh? what WERE we thinking with solder?) gave out, and it spewed it's internals onto the ground. I'll bet it generated all of 0.005 oz of thrust.....
So oh well, huh? We learned a lot.
I'm also an automotive engineer, but I love to design things and get creative. The sorts here who say
"You'll surely die trying this. Don't even think about it!" are uncreative nay-sayers of the worst kind. in their world, we'd all still be riding camels or horse carts. Yes, you actually
may die trying, if you actually even get off the ground, and there are a
lot of facts of physics that will vie to keep you grounded.
But think of what you'll learn just by trying, versus the guys who sit down at the local bar, watching inane stick and ball sports, and guzzling beer!
First off, the difference in air temp between inside the balloon and the atmosphere outside are key to taking advantage of the
difference in air density that would "encourage" your device to float upwards, the desired direction. Richard Branson used helium, and still had a
massive bag above him. Helium is expensive; you'd be better off generating hydrogen than trying hotter than air, but then, you have that little issue of combustibility. Hydrogen and helium can be contained in lightweight containers. Coal would not be even vaguely viable because of weight.
Wood as a material: would pretty much require a skeleton "space-frame" made of spruce with alloy connectors. (Expensive) The British learned this is WW II with the fabulously successful DeHavilland Mosquito.
Look it up. My dad was actually responsible for logging that wood species up in coastal British Columbia, where it still grows. Why spruce? Strength to weight ratio, but also it's amazingly tough, flexible and easily machined.
I once met Burt Rutan, a man you should perhaps contact. Tell him the Porsche engineer from 1987 recommended you call him. His company, out in desert California near Lancaster, is called "scaled Composites". Also get and watch his two DVDs about the race to get the prize for first private plane into space. His innovative approach and in-the-face of skeptics got him up to what? 120,000 feet, and his innovative re-entry technique was truly awe-inspiring.
You'll probably actually need a VERY lightweight alloy-composite frame with ultra-thin but tough polymer skin. Check out that human-powered aircraft that the cyclist pedaled over the English Channel. Same type of construction demands.
Next issue: propulsion so you won't be at the total whims of prevailing winds. Even an alloy Rotax engine, such as the UAV Predator or ultra-light use, will require a massive increase in the volume of heated air. There are also very small Wankel engines, but they have far too high specific fuel consumption numbers; you'd have to have too much fule on board to lift.
Then there's directional control and aerodynamics. All important factors, which will add weight, complexity and cost if you hope to be successful
Finally, you'd surely want a ballistically deployed recovery device; in short, a rocket-launched parachute, in case your balloon failed, or was caught up in structure threatening weather.
The design parameters are rigorous, and the construction means expensive, frankly. Even then, I'd say you won't be gayly floating along, with nary a care. You'd have to set down often, and in a world trip you'd be limited in the extreme as to how much you could carry, so you'd also need a pretty charmed American Express card. And that trip over the ocean would make Lindberg's problems seem minor.
I'd frankly suggest an ultralight. And, build a scale model first to see if it can even fly. You can buy a certified ultra-light aircraft kit, even a two-man (providing you with some baggage space, or be able to take that
uber-cute French girl you meet in Paris up for a quick flight over her home town and the family castle. Then she, and her daddy's Chateau, are your's for the asking!). You'd learn to fly, and you'd get off the ground.
So, go find a local flight center that offers ultralight flights, pay a few bucks and see how you like it.
Go for it! Enjoy, and learn.
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On a semi-posiitve note.....
