>>>This was also posted to the TLC home page chat<<<

For those who are skimming the messages, I will start out by listing the ideas followed by more detail:

1) Ice Sailers 2) A Groud Effect craft 3) A Hydrofoil 4) A Redimix type Cement mixer truck 5) Combustion-Electric hybrid drivetrains 6) Rocket propulsion (not soild fuel like the previous show)

Now for more detail:

1) A Ice Sailer is a one person craft propelled with a large sail. The sail propells the craft over a frozen lake surface on runners. An alternate design is very similar to wind surf board with ice skate runners. This is also possible with rollerblade wheels on a large aircraft runway. Racing the craft around a track could work. Scientific principal - wind force. BTW why not build indoors in the winter and move the projects outside? This would allow a greater variety of machines like snowmobiles, snowblowers etc. Summer is not necessary for construction. Trust me, I'm Canadian ;-)

2) A ground effect craft is a air plane wing that flies only a few feet above the ground (suggested once before by someone else). Because their is no open air under the craft, the ground acts to keep the pressure higher under the wing and is easier to maintain and lift is far greater and more efficient. There was some talk of mass producing these in a hang glider sized format for personal use. Sort of like a jet ski that flies above a lake. Unfortunatly, this is somewhat difficult to build. Scientific principal - air craft lift and (of course) the ground effect.

3) A hydrofoil is a water craft that has a wing (blade) under the front bow attached to a structural member. When the boat speeds up, the wing pushes the front of the boat up and out of the water. This design allows for reduced water resistance and therefore greater speed. A simple race between two water craft would work. Scientific principal - resistance in water.

4) A cement mixer truck (my personal favourite idea). The challenge is simple, give each team 3 bags of portland cement (plus aggregate and water of course) and a prepared forms down the road. They must build a truck capable of mixing the concrete and pouring it into the forms. The first team to fill the forms wins. There is several different ways to break this into a 2 team challenge like making one team use a conventional horizontal mixer and one use a vertical mixer (more difficult to build, faster mixing?). Or one team could build a very large mixer to mix all 3 bags in one and the other team could make a smaller mixer that mixes faster. Now build this onto a truck frame and the rest is a good episode! This also fits into the big & ugly & manly machines that JYW competions are often based on. Scientific principal - mixing and the chemistry of concrete. (**Concrete was invented in Britian)

5) The combustion electric power drive system. Most people do not know that a lot of mining trucks and other large equipment use IC engines to drive a generator and have electric motors on the final drives that connect to the wheels. Now in the junk yard, attach a combustion engine to a 3 phase motor and run the repective wires to another 3 phase motor. The AC motors should turn as fast as the alternator turns with a similar (reduces of course) force. I am not an expert in this area, but like a variable frequency drive unit it should work. As for 2 different ideas for two different teams, large engine large weight vs small engine small weight in a land race would work fine. Scientific principal - transforming energy into different forms and the loss when transforming energy.

FYI, I consider myself a JYW purest. All of the above ideas could be constructed out of parts in a salvage yard with a bare minimum of "seeded" parts.

6) For this challenge, give each team a litre of fuel and tell them to construct a rocket engine capable of lifting a .5 kg weight to the greatest possible height. There are serveral ways to build a engine such as using the traditional bell nozzle, a pulse jet, an aerospike, or a simple uncovered nozzle. This would involve seeding the yard with some parts such as spray nozzles with different patters, a valve, and an ignition source etc. To make it even similer, fuel is available that ignites when vaporized in the air (Chem 251 was too long ago for me to remember the name of this fuel - it is not commonly used because the ash is highly abrasive to nozzles) or two fuels that ignite only when combined.

Thanks for considering my suggestions.

Joe (jcw789@mail.usask.ca)

-- Joseph Widdup (jcw789@mail.usask.ca), February 25, 2001

Answers

4-6 are my favorites. I mentioned 4 before.

Think they can have the mixers make a couple of different pours. A side walk pour means they have to move the mixer while pouring and only pour out so much of the mix. You also have higher pours, say short pillars and such. They could have them make three or four pours meaning the team that has the most adaptable machine and controlled machine wins.

Really like your rocket idea, they could secure a safe place to launch and just watching a rocket go a few feet and explode is a real hoot too.

-- Richard James Retey (theswampie@cs.com), February 26, 2001.

Liquid fueled rockets can be quite nasty, mainly because of the fuels. Hydrogen Peroxide (much stonger than the drugstore type) won't pollute the environment if its spilled but you need a full body chemical protection suit just in case. The upside of H2O2 is that its a monopropellant, just needs a catalyst. Fuels that burn or otherwise react when two or more chemicals are mixed are called Hygroscopic. Very Nasty Stuff. Hydrogen peroxide can be used as 1/2 of the fuel in a hygroscopic rocket and was used in the WW2 German rocket plane. I forget what the other part of the fuel was. A hygroscopic system was also used on the Apollo lunar landers because its simple, just get the two fuels into the combustion chamber. Hydrazine is another good monopropellant. Unfortunately with the exception of H2O2 mono propellants are all EXTREMELY CAUSTIC, not something suitable for a rocket bashed together in 10 hours. Goddard's first liquid fueled rocket looked pretty primitive but I bet he spent a whole lot more time than 10 hours on it! :)

-- Gregg Eshelman (gregg1@valint.net), February 26, 2001.

I like the Wing In Ground effect idea, as well as the Hydrofoil and the electric/ic hybrid design.

The show based on these ideas can be pretty exciting too. A German company had developed a WIG similar in size to a light airplane. That company might like to supply an expert, or have the Junkyard warriors race against the "real thing" for comparison.

Several navies have hydrofoils, and Boeing once built a hydrofoil ferry. Unfortunatly, the HMCS Bas D'or was laid up many years ago, but the angled, surface piercing foils gave her "built in" stability (If she heeled over, the "down" foil would generate more lift, correcting the problem).

Toyota and Honda make hybrid cars, which could also be used as real life examples of what the teams are going for, although a giant "CAT" mining truck would be much more spectacular...

I have to agree with the post about rockets. Goddard used gasoline and Liquid Oxygen (salt the junkyard with LOx?), and most rocket fuels are sensitive, toxic, highly corrosive or all of the above. An explosion in the workshop or fueling pad would be pretty disasterous.

-- Arthur Majoor (a_majoor@hotmail.com), February 26, 2001.

For a rocket, you just need an oxidizer and a fuel. Here are two common ones: Gasoline and NO2. Even easier, though, would be a hybrid rocket, which is an option one of the teams might pursue: Spray an oxidizer through a tube lined with a flammable, relatively high-energy material like plastic or rubber. Rockets that spray NO2 through a burning PVC pipe (which lines a nonflammable pipe, of something like stainless steel), are not uncommon in basement workshops and suburban garages.

I agree that it would be fun to watch something like a pulsejet, but I wouldn't call it a rocket. If we want them to be qualified we might want a slightly more general term for the challenge, like "missiles."

-- TerranFury (i_have@no_email.com), May 16, 2003.