Doc Cathode's Harebrained Flying Machine Project

In My Humble Opinion
1

A few years ago, I was struck by inspiration. I would scrounge, and plan, and wait, and build myself an ultralight from things other people had thrown away.

Sure I have no knowledge of engineering, welding, aerodynamics or numerous other necessary things. But I refused to let that stand in my way. There were other difficulties and the project was put on hold.

 Then I realized that I had been so fixated on the idea of a trike-style machine, I had missed the obvious. If I instead built a backpack mount for the engine, fuel tank, and propeller, I wouldn't need any lower structure. The project just got smaller, lighter and a lot easier.

  But, I still have many questions. Are there any common materials suitable for making the canopy?  Is a glider-style canopy with frame best suited for this kind of thing? Or do I want to go with rectangular chute design? I've bookmarked sites for casting aluminum and for machining a 2 stroke aluminum engine. Is there any household item suitable for melting down for this purpose?

 Any other advice you can offer is much appreciated.
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When you crash & die, can I have your stuff?

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Well, if it were me, I’d make a jet engine or something to strap to my back, and find an ordinary hang-glider. And a very tall hill. And maybe some rollerblades. And a cardboard sign that says “Oops!” Then just wait for the roadrunner and…

4

Maybe I should start 2 more threads.

One would be for jokes about the Fantabulous Contraption Of Professor Horatio Huffnagle, ‘Each of us now has an unlicensed nuclear accelerator on his back.’, and so forth

The other thread would be purely for Dopers who felt the need to tell me not to do it.

BTW-I used to know a guy who did build a jet engine in his basement. It was one of a long line of father and son projects. The only problem was the lack of jet fuel.

5

Junked mag tire rims might provide the aluminum alloy you need in sufficient quantities to recast it for the engine block. You could also start drinking beer out of a can and just stop recycling for a few years.

Tubular aluminum tent poles might be reworked for struts if you go with a rigid wing structure. Large uninterrupted expanses of ripstop aren’t a common “found” item and a surplus parachute has too many seams to be of use for a skin. A canopy style airfoil will probably be easier to assemble from found materials.

6

If you are serious about this, Doc, then buy yourself a set of plans based on proven designs, & take it from there.
A lot of early aeronauts got killed doing things the “trial and error” way.

You can get some really cool plans from the back of Popular Mechanics.

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      • By far the easiest way to build a plane using only simple tools is the WWI (world-war-one) era way, out of spruce and doped fabric. Pine is the most common structural wood used now. It isn’t as stiff as spruce, but it might work well enough. You could just duplicate the original Wright bros-plane somewhat, but with a more modern engine. Use one big single wing instead of a biplane, you’ll get better lift. You don’t need an undercarriage, just arrange it so you can lay on top of the wing, as they did.
  • (I think) you are wasting your time trying to cast aluminum; it needs to be heat-treated after casting. The thicker it is, the more it needs heat-treating else it shifts and cracks. Steel doesn’t always need heat-treating, but it does need far higher temperatures for melting. I say use a lawnmower engine and skip this step entirely–you could spend a couple decades just trying to get a workable engine running.
  • The Paraplanes are the flying-parachute canopy things. They need a lot of power just to get off the ground–they usually have 40-50 hp, and only go around 14 mph on that. They are the safest aircraft to fly but are terribly fuel-inefficient–a “conventional” type wing plane built as above can get off with as little as 10-15 hp. You might be able to find a 10hp lawnmower engine in the trash–small riding lawnmower engines get up to 16hp or so. You probably won’t find any 50 hp engines in the trash, unless you go with a Volkswagon Beetle engine, which checks in at around 85 hp… and you probably won’t find a serviceable one in the trash. But you might be able to find one for free, especially if you’re willing to haul off somebody’s dead Beetle to the junkyard for them.
    ~
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Naturally it’s prudent to make and fly a few RC test models of your design before you plant your butt in a real homeade one. With regard to the engine, it’s probably best to use a pre-made one as it’s the most complicated part of the plane and there are many types out there that wold be suitable.

Hey Tuckerfan Get your hiney in here, we have a thread going!

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RE Engines-
A paraglider requires more hp than a trike? I’m confused.

Re-Plans
I haven’t got the funds to purchase plans, let alone the materials and equipment needed to complete them. Though for a long time I was looking for free trike plans on the net. If I found plans using aluminum tubing, I was planning on using old bicycle frames. I realize that there would have been problems with stress, exact weight, joints, and different frames expanding/contracting at different temperatures. A few sites did say that using 6 heavy duty off road bike tires was workable for landing gear.

The 2 biggest problems have always been getting a two stroke motor and finding material for the canopy/wing/whatever.

Re-Am I Serious
Considering how things are going in my life, bizarre projects like this are the best answer. The others are safer and much easier-a theremin, an rc blimp, a bat detector, a 1 seater pedal boat. The cliche is that you have to walk before you can fly. I haven’t been able to walk(speaking metaphorically) for a long time now. But I hope I can still fly.

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Doc, I believe I have what you’re looking for! Didn’t think of it until DougC mentioned the Wright Bros., but there’s some fairly inexpensive books that’ll help you out on this! The Boy Mechanic Series has an incredible list of projects

(that’s just volume one, BTW). Volume 2’s out of print, butcopies of it are available on eBay.

IAC, before you start this project, I suggest you peruse the catalog of Lindsay Publications. They’ve got books on pretty much everything you’ll need for this project (including a series of books on building your own workshop from scratch!), and they’ve got great service!

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Most old bicycle frames are not going to be aluminum. Cannon and other recent aluminum frame bikes all use oversized tubing, and I’m not sure that large of a diameter is going to be useful to you.

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      • Well, maybe I am also: an ultralight in the US is any single-person aircraft less than 254 lbs empty. There’s some other limitations as well, as far as max speed and whatnot. But there are some differently-shaped vehicles that fall under this classification: powered hang-gliders, conventional-style “trike” undercarriage aircraft, flying-wing styles and … powered parachutes. Of all these, powered parachutes take the most power just to get off the ground and maintain flight–they cruise at around 80-90% throttle.
  • Also, just to save you some time: aluminum tubing you want to avoid, unless you are experienced in welding it already. Thin steel tubing is much easier to weld than thin aluminum. And… bicycle tubes are bad to use-- they are often butted, even in cheap frames now. What that means is that the walls of the tubing are thicker at the ends than in the middle, because most of the joining stress is at the ends. The tubing walls may only be half as thick in the middle of the length of the tube than they are at the ends. So if you cut one in half and weld it at both ends, one end is going to be a lot weaker than the other…
  • Since we’re dreaming here, I think an electric setup would be cool–the lack of noise would be amazing. I’d probably be building loony projects like this if I had anywhere inside to keep them…
    ~
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Just thought of something else, the folks who inspired the movie Night Crossing built a hot air balloon out of stuff they had to covertly aquire. I don’t know how accurate the film is (and it doesn’t look to be on video), but I know they wrote at article about the whole thing for Popular Mechanics back in the late 70s/early 80s. They could give you an idea of what kinds of cloth to use for the wing.

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Actually, I saw this a long time ago. IIRC he claimed he was buying the fabric to make tents for boy scout(whatever the Soviet equivalent was called) camping trip.

Actually, I was already wondering if a Coleman tent would provide suitable material.

Re-Material
Any suggestions?
Canvas? Silk? Polyester? Mylar? A few sturdy airmatresses? Cardboard reinforced with Nerf noodles? What about Tyvek? Those free AOL cds?

Re-Bike frames
Drat. What about wheelchairs? Walkers?

Re-Workshop, fortunately a relative has a basement workshop.

Re-Cost
I’m a magnitude poorer than many of you seem to think. So far, the biggest outlay I’ve made on this was for the helmet I picked up at a yard sale.

Re-Feasability
It’s just the ordinary everyday things I can’t do. If I have enough time, I can still accomplish the impossible.

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Doc, pick up the Boy Mechanics series as it discusses building everything out of materials one could expect to find. The books are fairly inexpensive (shipping’s like $2.00 for the set), and if nothing else, they’ll give you tons of ideas.

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Ah, ultralights… I remember ultralights… >sigh<…

OK, Doc, the biggest problem you have is acquiring quality materials, or as I like to put it, how cheap do you want to get with aviation when it’s your butt hanging a half mile up in the air?

I’m 150 lbs and pretty sure I’d want at least a 22hp motor. Yes, it is possible to achieve flight with just 1/4 hp but you haven’t the resources of Paul MacCready nor his sponsorship by DuPont.

If you want to do this on the cheap {{{shudder}}} I’d suggest the parachute canopy/backpack motor. Go up to either an EAA, USUA, or ASC website and find a local group that has someone with one. Or at least a powered parachute (much the same, but with sit-down undercarriage with wheels and such). Take a look at these things up close and in person - the guys who own them usually can’t resist showing them off.

They do sell the paraplane setups in backpack form - I tried one on at Oshkosh one year, weighed about 65-70 lbs, can’t remember the horsepower but it was pretty low. The speed is about 20-25 mph for take-off, cruise, and landing. What DougC said about throttle - it’s not that they really take more power, it’s that they have very small powerplants so they need a higher percentage of the power available.

The cloth used for the fixed-wing ultralights I flew was always Dacron. That’s not the only possible covering. Not sure about the parachutes - but they ARE parachutes made of the same stuff as the ones used by skydivers.

As I said - don’t cheap out on this stuff. If you can’t afford to get high-quality building materials don’t do this. In flight structural failures are a Very Bad Thing - they can and do kill people.

Also, although a FAR Part 103 ultralight does not require either lessons or a license I strongly STRONGLY urge you to get some lessons!!!. You might even be able to trade/barter labor for lessons. Flying is NOT a natural act for a human being. There’s only two ways to do it - spend 20 years carefully researching and teaching yourself (as the Wright brothers and other early surviving aviation pioneers did, and even some of them died trying) or take lessons.

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One of those nifty autogyros might be suitable.

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I have heard it said of ultralights, “Never fly higher than you are prepared to fall.” The part of you that sits will be totally dependent on every screw, every cable. Are you comfortable with that? Everything hangs on that answer.

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For inspiration, you may want to locate the episode of “Junkyard wars” where three teams (UK, US, France) compete in building aircraft with methods and materials dating around 1900.

No aluminum used, fabric-covered wings with wooden shapers, the works.

Incredibly fascinating to watch - even though they were handed modern engines (50 HP) and airscrews, it was impressive to see airplanes taking shape in two days. The French and US team performed so-so - the French plane was by far the prettiest but rather ineffective, the British plane was ugly but flew like nobody’s business and the US plane - well, let’s not go there.

http://junkyardwarsonline.tripod.com/specials/flight/flight1.html

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Geez, you trying to get DocCathode killed?

Gyros - all rotorcraft - are even more tempermental, quirky, high-maintenance, difficult, and (in untrained, inexperienced hands) more dangerous than any fixed-wing or 'chute-winged aircraft.