Powered Glidersgreenspun.com : LUSENET : Junkyard Wars : One Thread
ESCAPE FROM KARGO ISLAND
Three intrepid explorers are stranded on Kargo Island, a forgotten dot a mile from shore in the Mojave Sea, sacred to the local Cargo Cult natives who will have you for lunch as soon as they can patch their boat and find the paddles, a task that will take precisely ten hours.
The island is larded (and salted) with a bewildering array of Teknokulture residue deposited there by the Cargo Cultists (hence its sacrosanct nature). If you can escape from the island there is an RSP colony (Really Swell People) on the mainland who will scare off the Cargo Cultists, rescue your buddies and give you the name of a travel agent so you won't have this problem in the future.
You can't use a boat because the Mojave Sea happens to be dry at the moment. You can't use a vehicle nor can you walk since there are hoards of sandworms and patches of quicksand. Using a hovercraft is out because I said so, okay?
You'll have to build an airplane. (Work with me here.)
Fortunately, there are lots of airplane wings on Kargo Island. Unfortunately, no two are precisely alike and those that come close have some minor problem, such as missing an aileron or section of the leading edge.
Alas, while the Cargo Cultists have a positive THING about wings they passed up every fuselage. No tail feathers, either. But there is heaps of EMT and other tubing, some square, some plastic. And wood. Lotsa wood.
Did I mention the wheels? There's one now, rolling by. Some more over there... wheels are not a problem. Nor are engines.
Is that a Volkswagen bus I see? Sure enough! Two, in fact, an old splittie and a later ‘loaf, both with engines. There is also a couple of war surplus generators powered by Military Standard 4AO-84 engines, the ‘baby Continental' as well as an Onan generator (junked because of the obvious grounding problem) and a modern OHV vee twin 16hp something or other. Lotsa engines, sorta like the bear's porridge - some too hot, some too cold but - maybe - a couple that are just right.
Your task, should you wish to accept it, is to throw together a fuselage mit tail feathers, yet. Hang a pair of wings on it, stick an engine on the thing and fly ONE MILE across the Mojave Sea to fetch help.
Propellers? Well... maybe. And I DID say there was lotsa wood.
Struts? You may, if you wish. Or you may elect to use wire bracing... I think I saw a spool of oil well messenger wire somewhere. Fabric? Foam? Aluminum tubing? Pop rivets? Engine lathe? I'm sure you'll find some of those about... if you look hard enough.
- - - - - - - - - - - - - - - - - - - - - - - - -
Impractical? Certainly not! At least, not in the United States where we enjoy a certain latitude in airplane licensing not allowed in Great Britain. (After all, it DID start with a pair of bicycling brothers from Dayton.) The Amateur-built, Experimental license category is more than sufficient for a one mile hop across the sands of the Mojave Sea.
The basic equation of flight is quite simple, with Weight and Drag on one team opposed by Lift and Thrust on the other. Assemble a stringbag from a collection of parts and it takes surprisingly little power to keep the thing airborne. The trick is getting airborne to begin with.
No fuselage? Easily rectified... if you can weld and if there's a bit of thin-walled steel tubing about. Or even a few sticks of pine and a pot of fast curing glue.
No tail? Even easier to rectify, given a hickey, some drug-store aluminum tubing and a few pop rivets. (Didja know urethane varnish does just fine on polyester?) You can have your basic elevator + rudder, or mebbe a Bonanza tail, either up or down. Or a box-kite type. Or a canard. Or... whatever your ingenuity can provide.
Ditto for the engine mount. Tractor? Pusher? Direct drive or belted? Mebbe a chain drive? (A mile isn't very far.)
Landing gear? Or take-off dolly? Monowheel? Inline dualies? Trike? Conventional? Dolly take-off, skid to land? It's up to you. You're the Mechanic-in-Charge.
One nicety is balancing the area of the wings by the volume of the tail group... but that isn't a problem if you're an Intrepid Explorer (and can do basic math).
- - - - - - - - - - - - - - - - - - - - - - -
Want to talk serious Insanity?
After escaping from Kargo Island, replace the expedient bits of the birds with more suitable fasteners and hardware, get the props properly balanced and the engines properly mounted and then FLY THEM TO OSHKOSH.
Might take a while. After all, a Jerry-built stringbag is little more than a powered primary glider, safe as houses but slower than molasses in January. But the odds are overwhelmingly in favor of such simple airplanes surviving their hedge-hopping way across the United States (easily paced by a camera crew in their sag wagen). And on their arrival about 2.6 million people will be immediately aware of the Saga of the Junkyard Kites.
- - - - - - - - - - - - - - - - - - - - - - - -
Just a crazy idea of course. Probably never happen in the con-torted world of today where we've sacrificed fun for unstable security.
But man really CAN fly... with a bit of help from his friends.
Robert S. Hoover (EAA 58400)
-- Robert S. Hoover (veeduber@Pacbell.net), February 15, 2001
I'm not so sure. One season the teams did attempt flying machines, and the one team which stripped wings from the airplane was airborn for about 6 seconds (this includes an assisted take off where a winch accelerated the aircraft to @ 50 kph). The hang glider didn't work much better.
Would you include a winch or bungee cord launcher? What sort of designs could the experts come up with that have sufficient static stability and saftey so the pilot won't be splattered over the lake bed? (would there be enough variation for the "two kicks at the cat?")
This is interesting, to be sure...
-- Arthur Majoor (email@example.com), February 16, 2001.
Beats me if you can build something reasonably safe in 10 hours, but I REALLY appreciate Robert's attempt to fully flesh out his idea. It's way more useful than, "I thinnk snwomobils wud bee cool!2!@#!"
-- Rick Tyler (firstname.lastname@example.org), February 16, 2001.
Dear Arthur and Rick
With regard to the previous glider challenge, the design which utilized the all-metal wings appeared grossly inappropriate in that the wings were too heavy for the configuration used. At a guess, given their airfoil and span, minimum flying speed would have been 45 mph (ie, about 80 kph). A better choice would have been to salt the junkyard with wings from an Auster, Titch or Jodel. I suspect British civil aviation regs had more to do with it than did the realities of building a flying machine.
In the case of the Rogallo configuration the CG appeared to be too far aft.
In the United States it would be quite easy to salt the yard with wings of more appropriate design, such as those from an early C-120, Taylorcraft, Texas Parasol or similar. Indeed, in the States it would be easy enough to have several such wings built specifically for the production, artfully aged and distributed about the yard. (Following WWII there were a number of junkyards in the San Fernando Valley literally stuffed with aircraft wings, fuselages and engines.) Fabricating a fuselage in a Northrup configuration is child's play for someone familiar with the design (as all true junquemeisters should be) and the fabrication may use pop-riveted aluminum tubing (or extrusions), welded steel tubing (square or round) or even wood, although the engine mount and landing gear should be welded.
It would add to the dramatic interest to salt the yard with a drum of bungee cord but it would be partly a red herring. If the teams had their wits about them they could come up with several powerplants capable of delivering sufficient thrust to allow such an aircraft to take off under its own power. Properly configured we're talking about a flying speed of about 30 miles per hour (54 kph)
As for safety considerations, all else must yield to that end since it would do the show no good to damage a contestant on camera. Fortunately, the design of a Northrup-type primary allows for a robust structure at minimum weight - the pilot would be well protected.
Of the engines I mentioned, even the largest would need less than a quart of fuel to fly a mile. A crash-tolerant tank having a capacity of one gallon would be more than enough for the show. And if the Suits insisted, the use of packaged powerplants would reduce the probability of engine-related disasters to a number vanishingly small.
With regard to variation, given that each team would have to fabricate their own tail surfaces the viewer would see two visually distinct designs. If one of the salted power packages used a belted reduction unit while the other drove its propeller directly, these considerations would trickle back through the design since the selection of the powerplant would dictate its mounting, which in turn would dictate the configuration of the fuselage structure. Additional visual distinctions would be dictated by the selection of the wings, with some designed for wire bracing, others for struts. Because form follows functions the designs would be similar but visually quite distinct.
In principle, flying machines are quite simple, certainly less so than many of the devices constructed on the program. Yet despite their simplicity flying machines embody a wider range of technological competence than anything the program has attempted so far. I suspect the real limitation here is not the production company's constraints but the competitors skills.
Robert S. Hoover
-- Robert S. Hoover (email@example.com), February 16, 2001.
Excellant suggestion. You're a bit whacky in delivery. (like I'm not)
call it the flight of the Pheonix. The bird that became extink and return from the ashes (did I get that right? Websters)
I have little flying background but would have a blast working on that project.
Hey if they can have a bunch of kids on an isleland for 10 weeks called Shipwrecked then why can't the more imaginative people (that's us) build an aeroplane and escape certain....death? It would be costly I'm sure. Media advertsing would cure that. To find an isleland stock it with our 'junk', a massive generator for all the power tools. Oh yea you said wood. ah, ok hand tools and you have to carve some parts for assembly.
Not to make light of your idea it's probably the most sane yet. Count me in. I'll bring the sand paper.
-- Jerry Johnson (firstname.lastname@example.org), February 16, 2001.
Can one team be the escapees and the other be the tribe? One has to get the plane off the ground and the other has to build a water ballon canno, gun, whatever...to shoot the "thiefs" down before they get away...
I really like the ideas of scenarios...I think that it would add a lot of flavor to the show and add a lot of materila for the hosts to play with...
-- Dan Denney (Rustrenegades@hotmail.com), February 16, 2001.
finally someone has a post that exhibits some degree of eloquence!... a very nice presentation!.....a merit which demands recognition!.....and a good subject too!
-- tim (email@example.com), February 18, 2001.
My experience with planes is rather limited; being a passenger in full sized ones (usualy built by Boeing), or launching rubber band powered ones (a long time ago). Canada's regulatory environment is pretty tough for people who want to build airplanes, so there isn't a big pool of experience up here.
One thing that I do remember from the small models is the "best" design was a high wing monoplane with a tractor propeller. These planes were stable, even in fairly windy condition, tended to follow a straight line, and landed well. Some of the more ambitious models looked good, but had lots of vices in the air, and usually arrived on the ground in a spin, stall or power dive. Good thing Balsa wood was so cheap in those days....
Just how far do you want the teams to go? I am thinking the weight and balance problems of fitting dissimilar wings might make the airplane hard to fly. Would you "salt" the junkyard with fabric so they could make their own wings? (Fabric streched over steel tubing, a la WW I.) If the teams could use some sort of varnish or fast drying doping agent, the wings should be dry and ready to go the next morning, or am I barking up the wrong tree here?
Speaking of trees, what sort of landing gear would they have? Some sort of shock absorbing would be required. Or perhaps they could fly into a big net? (See the "Full Stop" thread).
Anyway, lots of interesting things to think about.
-- Arthur Majoor (firstname.lastname@example.org), February 18, 2001.
Why not make aircraft with steam engines? Now that would really be a challenge, and would likely eliminate the danger of too much altitude being lost too quickly. I don't think the FAA would approve of a boiler flame in an aircraft however.
-- Waddy Thompson (email@example.com), February 18, 2001.
Arthur Majoor writes:
- - - - - - - - - - - - - - -
The language of aeronautics, like that of music, is international. Canada has more than its share of superbly skilled aircraft builders and pilots. Your regulations are actually less stringent in some categories than those of the United States. If, as a Canadian, you wished to build your own airplane, you would find it not only relatively easy to do but quite commonly done. The Canadian Experimental Aircraft Association is devoted to that activity and has tens of thousands of members from Inuvik to Halifax. A search of the internet will provide a number of leads should you wish to look into the matter.
- - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - -
You are correct in that a high wing parasol offers certain advantages with regard to stability, as compared to some other designs. The Northrup primary glider is a high wing parasol, for example. But the probable use of that configuration for a challenge aircraft would have more to do with its ease of construction. As for stability, see below. - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - - -
Although I believe you meant that with regard to fabrication, to preclude the chance of misunderstanding... I originally suggested a challenge distance of one mile, which would be flown in straight line. There are many dry lakes near Los Angeles where this type of activity is allowed. Most offer at least two periods of calm during the day, one shortly after sunrise, the other after sunset but before full dark. Conducted during those periods of calm, a one mile straight-line flight with a maximum altitude of perhaps fifty feet would present no stability problems that could not be overcome by the stability inherent in a high wing parasol design, assuming the weight and balance were within normal limits (a point the assigned expert would surely enforce). - - - - - - - - - - - - - - - - - - - - - << I am thinking the weight and balance problems of fitting dissimilar wings might make the airplane hard to fly. >>
- - - - - - - - - - - - - - - - - - - - - - -
This is less of a problem than you may realize. The truth is, no aircraft is perfectly symmetrical. In flight, you adjust the trim so the minor differences appear to vanish. In fact, it's possible to fly quite well with wings of different area, so long as the difference is within the controllable range of the opposite aileron. The critical safety factor under such conditions of asymmetry is the coefficient of lift, which is determined largely by the wing's airfoil and angle of incidence. A pair of wings having the same chord and airfoil but having a 10% difference in length (and of course, painted in different colors :-) would actually match quite well in aerodynamic terms.
(For an actual challenge I suspect the producers would simply use a collection of IDENTICAL wings but having different tips [ie rounded vs square] and different paint jobs, hull numbers, etc. An majority of viewers would see these as uniquely different wings.)
As for the weight and balance problems, that would be part of the expertise demanded of the challenge. So long as the finished airframe was statically balanced on its pitch & roll axes you should expect it to perform quite well, at least at the speeds intended for such a challenge, even if its aerodynamic balance required a bit of stick & rudder to maintain straight & level flight.
As a rule of thumb, the point of balance should fall at about 25% of the airfoil's chord, on the centerline of the fuselage, with the airframe fully laden for flight. It won't, of course. It will be up to you as the Mechanic-in-Charge to insure it does Fortunately, thanks to the long moment arm of the wings and fuselage it takes a surprisingly small amount of weight to achieve the required balance.
Of course, balance weights detract from the airplane's abilities. If you can do without them, you should. The poise or balance of the airframe would be a primary concern throughout its fabrication so that as the challengers neared the deadline they would shift the position of the PILOT to achieve perfect balance (at least with regard to pitch) before welding his crash cage to the airframe. Lateral balance would then be achieved by adding weight to the light wing tip. - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - - - - -
Wrong tree entirely. I specifically mentioned salting the yard with wings because that is the secret of success. Even the wings of a ‘Texas Parasol' (a popular homebuilt design) would take three men about twelve hours to fabricate.
The yard would have to contain some sort of covering material to complete the tail surfaces. But for a flight of only one mile almost anything reasonably light and impermeable would work – there's really nothing very exotic about a fabric covered aircraft in the SHORT TERM. All of those layers of dope and varnish and paint are to insure safe operation over a span of decades and at flying speeds greater than anything that would be allowed here.
If someone happened to leave a couple of bolts of 100% polyester fabric laying about the yard, given a sewing machine and a hair dryer, we could in fact cover a complete wing. But the real object of the program is to sell soap and to do that it must offer a level of ENTERTAINMENT at least as high as its level of technical expertise. I n that regard, watching a team cover a wing with fabric would be about as interesting as watching paint dry. However, some colorful PATTERNED polyester material (!!) would surely be found to cover the tail feathers. Or perhaps patch an aileron. That would be more than enough for the viewer to understand the process. I assume one of the presenters would expand on the principles involved.
(Polyester is the generic name for ‘Dacron,' a du Pont brand named fiber. Dacron has the interesting property of shrinking at a controlled rate when heated. In the early days of aviation aircraft were covered with grade A cotton which was shrunk taut with water and then sealed with nitrocellulose dope. Today, dacron has become the fabric of choice, although cotton and linen are still used on some antique aircraft. The ‘sails' used to cover the wings of ultralight aircraft are made of pre-shrunk Dacron. But polyester suit-lining material will also work, at least for an aircraft as light as the one envisioned here [ie, a maximum of 500 pounds and a wing area of approximately 100 square feet]). (As a point of interest, I'm not aware of any WWI aircraft that used steel tubing as the primary structure of the wing. Most used wooden spars & ribs with a plywood leading edge, the whole covered with fabric.) - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - - - - - - - -
Strictly speaking, a LANDING gear is not required, a skid would do perfectly well and serve as a brake too. But a skid offers too much friction to allow the plane to take off.
Most probably, the landing gear would consist of a single wheel, possibly from a wheel barrow. Thanks to the low weight and speed, no other form of shock absorption is required. The plane will attain aerodynamic balance almost as soon as it begins to move forward. Initially on taking off, the wings would be steadied by the other team members, exactly as with the Wright ‘Flyer.'
To insure adequate weight handling and energy absorption you might need to use two (or more!) wheels if all you could find were little ‘uns. They could be configured either fore & aft or as a boogie pair. Anything more elaborate would only add weight(*). If all you could find were hard rubber or plastic wheels then you would have to provide some form of energy absorption. Bungee chord would do. Or just a piece of springy wood (!) Anyone familiar with aviation will be familiar with such systems, which were quite common in the early days and are still seen today on many antiques. Lindbergh used rubber bungee cords, for example. Such systems work perfectly well but modern systems offer better durability at less weight.
(*) If the challenge aircraft were to be flown across the country to the national fly-in at Oshkosh they would be refitted with a more suitable landing gear.
-- Robert S. Hoover (firstname.lastname@example.org), February 19, 2001.