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11-Pound Model Plane Vs. The Atlantic
merrell writes: "Apparently some model plane builders are going to send some balsa wood loaded with some tiny computers and GPS receiver across the Atlantic, running on less than a gallon of gas. The Washington Post has an article on it. Just goes to show what some retired NASA engineers with lots of free time can do. :)" If this was a movie, it might sound too unlikely.
or if it flies too high, it'll get burned by the sun!
"And then we added a few pounds of high explosive and changed the final co-ordinates to something more interesting." Wonder what the waypoint accuracy of this thing is? Dropping bombs down airshafts not just for the USAF anymore! Wheeeee!
Ha, a good engineer will go to any amount of effort to avoid extra effort.
Balsa isn't strong...yeah right. You are right, it's not strong. Strength comes from engineering. In a high school Odyssey of the Mind competition, we build a struncture out of balsa, and super glue, that weighed 8 grams, and held in excess of 500Lbs. We used all the weights availabe, and it still did not break. We tried an experiment on our own, and found that it held 800lbs for 10 minutes. 10lbs/gram! Our play sucked balls, and we lost to a group who had some big chested girls. So much for Odyssey of the Mind!!!
The mylar they are using is pretty impervious to weather. My son lost a R/C plane in a corn field, and we didnt get it back for almost 3 months. It had survive pretty well except for the radio equipment. They say they are using camp stove fuel, which means they are probably using a 4 cycle engine, and an ignition system. A 2 cycle engine does not have the fuel economy that is needed for this. Also with the ignition systme, they are getting telemetry for the engine RPM.
Check out this!
http://www.insitugroup.com/LaimaFlight.html
This plane was a little bigger, and made mostly out of carbon/epoxy composites, but it weighed 29 lbs and flew trans-atlantic on a gallon and a half of gas! The first unmanned trans-atlantic flight ever!
The University of Washington Aero/Astro department is trying to build one to cross the pacific first too, but those guys at the air force beat us to it. Of course, their budget was MUCH bigger than ours.... Our airplane is only 50 lbs and 6 feet long!
Things that weigh less are less likely to be torn apart in the wind. They have less inertia, and so will simply move with it instead of breaking. Being slammed into the ocean isn't a problem if they don't fly really low. The main problem would be prevailing winds opposite the direction they're going, forcing more fuel use or something like that. Since the winds are usually west-to-east, this shouldn't be a problem.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
This is what you get when you let brilliant minds do whatever they feel like doing. Somehow, it feels more valuable than what a lot of my working friends are doing at dot-com flameouts.
There's a lot to be said for letting brilliant people do whatever they want, without giving them much money. It's this sort of spirit that used to drive dot-coms, back before incubators, before the stock boom took off and everything was about stock valuations. Suddenly, millions of dollars were flying around, and everybody was under pressure to turn it into profits.
What's your damage, Heather?
Now this is great to see. We need more projects like this to keep bored retirees off the street and away from the temptations that are offered there. Why just the other day in the neighorhood Denny's, I was accosted by a grim little man whose bravado was no doubt enhanced by the support of his fellow grandslammers. He yelled in his reedy voice, "Hey buddy! I got my social security! And you're paying for it!!!" which was followed by the raucous laughter of his comrades...
Today, there are dirigible-carried radars along our southern borders watching for smuggling planes. Will they see a plane like this, flying at a few hundred feet AGL? Not likely!
The only good weather is bad weather.
Wow, what an interesting new device for drug trafficking. Strap the dope in the pilot's seat, fly that sucker at just above tree-top level, send it to Cousin Vinny... Hell, I don't know anything about it, but if this model plane can make it across the Atlantic, then it can certainly carry drugs across a border.
I'm sorry, I meant to make a quick and interesting post, not write a monograph on the various mechanical properties of wood.
I rather thought that what I meant could be at least roughly deduced by the reader by refering to the subject at hand.
I meant in overall properties, given the certain structural shapes and assembleges germain to stick built objects such as houses, cars, and . . . model airplanes.
As you intimate structural materials have many different properties. Wood, unlike steel, is not isotropic and so its properties are greatly effected by its orientation to load, at least in its natural state. Bear in mind that there are many high tech composite wood products these days with rather remarkable properties. But since the subject is balsa I'll confine myself to wood as she comes from the tree.
Wood has a tensile strenth of about 5 ton f/in.^2, mild steel is about 28.
Mild steel has an elongation percent at failure of about 20. Wood is close enough to zero to count. In a situation where dimensional stability is of higher importance than unltimate failure strength wood is often the superior choice.
Mild steel's Young's Modulus is about 30 lbf/in.^2 * 10^6, wood only about 1.5. Wood is less stiff than steel, however its elastic limit is very, very high. Wood will bend and return to its original shape in ways that make it in many cases a more desirable structurual material than steel.
But things get REALLY interesting when we start to look at beam strength. Beam strength goes up by
* the square of the cross section.*
Given the need for a particular beam length, ohhh, say the main spar of an airplane wing just to pick a hypothetical example at random, and the need to keep weight down, a wood beam of * the same weight* will be of markedly greater cross section, and again, * strength goes up by the square of the cross section,* The wooden spar will be stronger than the steel spar. Or we could, as an alternative, make the wooden spar of somewhat smaller cross section, giving up strength but * saving weight*.
It would be perfectly possible to build model airplanes out of steel. It isn't done not because of cost,(steel is cheaper than balsa), not because of constructiion difficulties, ( balsa plane construction is no piece of cake and working with steel isn't significantly harder), it is done because it results in a structurally superior product * per pound* than using steel would. ( And please note that when the cross section gets sufficeintly large it is perfectly possible to gain all the benfits of tubing with wood. Sailboat spars are constructed this way as well as wing spars for airplanes)
Using stressed skin construction makes up for wood's low Young's modulus yielding remarkably stiff structures.
That, in a nutshell without writing a formal monograph, which I refuse to do, is what I meant by 'strength.'
When we get into the more modern composite materials wood looses some overall 'strength' but gains isotropicness.
In the field of military aircraft two planes in particular, from two different world wars, stand out as having such a reputation for sturdiness and ablility to take fire that they are legends to this day. From WWI there is the Roland C-2 "Walfisch", and from WWII there is the Mosquito. Both of these planes were molded wooden composite. The Roland was so sturdy that by the end of the war the tailgunners were in the habit of shooting at enemy plane * directly through their own fusilage!*
Now THAT is strong, but you won't find that kind of 'strong' in any engineering reference or ANSI standard.
By the way, what are YOU smoking. You havn't a clue what the terms softwood and hardwood mean. The gentleman in the post below you got it right. Go look it up.
Oh, and you COULD have correctly criticized me for one thing, I should have said "botanical" classification, rather than " biological", but you missed my ACTUAL error. Go figure.
KFG
Now go and ask yourself that question.
--
Escher was the first MC and Giger invented the HR department.
Sorry, but honestly, I can't wait to see a commercial app out of these. Newspaper companies could use fleets of them to deliver papers (particularly to remote houses). Fast Food companies could one-up drive throughs. It could even solve some of the US Postal Service's troubles
Of course that begs the question: aren't we lazy enough already?
Kurdt
Kurdt
I'm not anti-social. Just pro-technology.
The real question is whether the weather will work in their favour. Assuming that they have a model that will fly the distance. If it's too sunny the wings may warp (twist) causing an increase in drag and more problems for the autopilot. IIRC rain doesn't mix well with mylar, although I'd guess it's been sealed because of engine output (fluid etc.). They didn't say what king of engine they are using, if it's a glow engine they may get more problem with rain.
I'm not quite sure why they didn't build a glass fiber model. It isn't that difficult to do. They usually run well in the rain, if slower.
It should be interesting to see how well they do.
--
Murphy Bitter
"Opening at an airport near you Hamster Airlines. A low cost solution to moving you pets."
--
Murphy Bitter
P.S. I have heard of people putting hamsters in models, they usually don't survive. The G's are usually way too high.
We humans tend to notice wind as very turbulent because
Life is like a web application. Sometime you need cookies just to get by.
-- Chris
-- Chris
$email=~s/[^a-zA-Z0-9@.]//g;
Now all we need is for someone to write the three-line-perl-RSA-implementation on the side of it for the most stylish arms-trafiking stunt in history.
Seriously tho' doesnt it occur to anyone that if this does succeed, it could have very serious implications for smuggling (Like thinks how much crack this thing could carry with it per-flight with a little modification),
Of course the simple internet minded solution would be to legally threaten the balsa-growers, the plane-sellers, and the gasoline-vendors while letting the crack whores continue unmolested.
------------ Dom Howells
use Blunt::Instrument;
As a kid I used to build "stick and tissue" CO2 powered models with a simple pendulum "guidance" system. Trickiest part was getting the right amount of friction at the pendulum pivots to keep the model from over-compensating, and to design around the center of gravity shift for the pitch control. Once the rig was setup properly though, you could "program" it to do all sorts of neat stuff, by offsetting the pendulums. Balsa kits were around $5.00, and pendulums were made from fishing weights and paper clips.
Mommy. What's a karma whore?
Smuggling isn't a problem. I work in a secret government lab, we are already training genetically modified seagulls to bring these babies down (at least during mating season).