One thing that got to me when watching the shows, how I would have done it differently. Here are some of my thoughts (various shows)

Cannons:

One possiblility (but one that would not have occurred to me if I hadn't seen the brothers machine in "operation". Ever seen a "nerf pistol"? Turn the cannon inside out. Use a truck axle as the barrell, with a capped bit off tubing "scaf pole" as the projectile. Use a laser pointer to aim.

Submarines:

I already put up alternatives to our design. As to the opposition: Well the air drive didn't have the range to finish the course. But it would have helped if the dive planes were on the front, the hull got shortened, and the exhaust got collected to provide adjustable buoyancy.

This should get people started: What would you have done?

-dp-

-- Jeff - The NERDS (dp@the-nerds.org), January 07, 2001

Answers

Well, Jeff...what if your submarine had included an internal bouyancy compensator...perhaps an innertube or a can with a valve on it stuffed into a chamber and filled with air, then deflated in the tank to adjust the thing appropriately. Obviously you guys thought of it 'cause it appears that what you did...at test-time... 8-)

In the US cannon (gourd tossing) segment just aired last week...which looked oddly familiar, I thought...I think the team with the air cannon wasted their practice shots fiddling with pressure...once they got one good shot they should have kept the air pressure constant and fiddled with the trajectory to figure out how to aim the thing right.

--Dave Althoff, Jr.

-- Dave Althoff (dalthoff@capital.edu), January 07, 2001.

I found the use of bicycles to build up air pressure to be a tiring way of doing it. In both series, the bicycles has small gear reductions, causing the teams to have to sweat it out, to get the pressure up. Why not use a large wheel (one of the bicycle wheels would have worked) mounted on a stand, with a handle on it. Using a belt connected to the compressor pulley, they could have got more revs out of the compressor per turn of the wheel, and not had to pedal to exhaustion.

-- Rick (rsrickard@hotmail.com), January 07, 2001.

The Rusty Juveniles had an adjustable gearing via the manual gearbox, which I thought was brilliant ;)

The Beach Boys as far as I can tell had fixed gearing.

-- Dan Hollis (goemon@blort.invalid), January 07, 2001.

In the same vein, Jeff, what about you? What would you have done if you were in the Brother's shoes in the final? You are building a big dragster.

I assume that the "Test early, test often" would have found the transmission problem. What would you have done then?

-- Michael (Canadian P. Eng.) (michael@mks-tech.com), January 07, 2001.

No doubt. Using the transmission to gear the bicycles was very ingenious. Though I wish they (producers / editors) had spent more time discussing it.

-- Rick (rsrickard@hotmail.com), January 07, 2001.

Had we known 20 lbs of airpressure would be enough we would have turned the transmission around. Waddy, our expert, originally thought it would take about 60lbs to get the job done. As to the pulleys, that was the largest pulley, for a v-belt, that we could adapt to the bike rear axle. and I wanted a pulley designed for a v-belt, for the smaller pulley, we used the water pump pulley off the taxi, a chevrolet V-8, because of the diameter of the hole in the center of it. If you noticed both pulleys ran straight and true. The resistance from the compressor at pressure is far greater than you might imagine, I could put my thumb over the outlet, and geared up about 6 to 1 as we were, I could stop you from pedaling.

I don't know about Jeff, but, I surely would have known the transmission didn't work before we got to the track.

A lot of people have asked why they didn't see me do more welding etc., it is probably because I don't wear dark glasses or a welding helmet for oxy-acetelyne or mig welding, I do with a stick welder and tig. Don't start yelling, I've been doing it for over 40 years and I have my eyes checked regularly and the way I do it presents no problem. The stick welder on the show was rather wimpy, but still too large to weld the bicycle chain.

JustJay

-- justjay-Captain-Three Rusty Juveniles (justjay@neo.rr.com), January 07, 2001.

As to compressor gearing, work is work. They would have to expend the same amount of energy, no matter how they geared it. About the only thing that gearing might do is make it a better or worse fit with optimum "engine" speed. (gentlemen, start your gentlemen)

The beachies air cannon should have used a sabot, like you did, wadding isn't enough. Wasn't a problem, but it would have given them much higher numbers.

As to the US dragster, the firemen should have not have used any sort of driveshaft, and thus put the engine a lot further back. And the scrap daddies should have skinned more of the frame, if you are down on power, you need all the aero help you can get.

With the dragster, we certainly would have tried the transmission well before welding it into place. But I do wonder what the problem was. If it was something like a plugged bit of valve body, preventing first gear from engaging, I would have been tempted to try to just engage second gear by "adjusting" the second gear band to provide a somewhat higher top speed. (with wrench or welder).

For the beachies, air cannon, they left the derailers in place, so they could fine tune the ratios.

On their steam car, a U joint at the shaft coupling, and moving the boiler closer to the center of the frame. (I would have used a van chassis for the extra room)

As to adjustable buoyancy, we didn't find anything that was in current test that we could put air in. (and we wern't allowed to pass it thru the divers lungs first)

-- Jeff - The NERDS (dp@the-nerds.org), January 07, 2001.

I noticed on the "Beachies" air cannon, that the wadding was coming out of the barrell a long time before the ball came out, so they were blowing the wadding around the ball. Wadding causes a lot of drag in a rough steel pipe too. We have tried about everything you can think of with the melon muskets, and have found that a well lubed tight fitting melon is the best for range. We also lube the barrell with a venturi blow gun when shooting melons. We had no idea that the air cannon thing had already been done at the time we were taping the US version. I really liked the steam car challenge, as I have been collecting parts to build a steam engine. It will be operated with compressed air though, and will be for show when we go to shoot melons. There is something about a big flywheel turning that fascinates people.

-- Waddy Thompson (cthomp3851@aol.com), January 08, 2001.

Jeff, It was intresting that your team knew that the optimum crankshaft speed for the "junkyard" steam engine would be 750 rpm. Did you calculate that from the boiler rating, or expected operating pressure and expected crankshaft torque and engine displacment,or was it on the nameplate of the engine? Another thing I have wondered about is what caused the sieze up with one of the steam engines? Was it seized pistons, or a crank bearing, and did it have anything to do with welding the crank to the tranny?

-- Waddy Thompson (cthomp3851@aol.com), January 08, 2001.

The 750 rpm is just typical redline of that size/design of engine. Richard just knew it. (the beachies had a bigger problem, their engine would be difficult to get above 500 rpm) In general, steam piston engines are much slower spinning things.

They didn't do enough about engine oiling. Also we didn't have the best oil for steam engines. They seized one of their low pressure cylinders. Not sure if it was one of the valves (piston style) or one of the power pistons. Their engine was harder to oil, because it used the steam in series. Our engine with one cylinder, and slide valves, was very tolerant of poor lubrication. (and it had a fine displacement lubricator)

Remember you have to add the oil to the steam, you can't put it in the boiler. (and thats something you will have to pay attention to running on compressed air) Use an air tool lubriactor.

-- Jeff - The NERDS (dp@the-nerds.org), January 08, 2001.

Yes Jeff I know "work is work" and the same amount of energy is expended. What gearing does is give you leverage, so you can do all the work at once in one go (if you're superman) or in little bits across a long period of time (for us mere mortals).

Of course Rusty Juveniles didn't load their receiver up to 120psi either, but I suspect the Beach Boys would have had an easier time of it had they had variable gearing.

-- Dan Hollis (goemon@blort.invalid), January 08, 2001.

Thanks, Matt. I will be using an air oiler, as they are something that we change out every year or so on air operated veg. packing machines. I plan on using an air cylinder and a hydraulic spool valve to make the first version of my air engine. Another option is to use two three way solenoids and operate them with a microswitch or photoelectric switching, making a sort of cross tech electric/pneumatic engine. That's the system that they use in machines that assemble pasteboard boxes, so used parts are easy for me to get. I have a lathe, and will be making a cylinder and valve for it that will be more "steam engine" like eventually. The flywheel that I have is similar to the one on our air cannon, 34 inches in dia, with a 24 inch flat belt pulley cast on one side of the spokes. Maybe the original design of the engine that locked up called for a cotton wadding type oiler in the steam feed line.

-- Waddy Thompson (cthomp3851@aol.com), January 08, 2001.

Whoops. I didnt read the bit where they left the derailers in place.

They didn't make that clear in the broadcast, and it looked to me like they had just connected the pedals directly to a drive shaft with fixed gearing. It can be hard to make things out on low-res television sometimes :P

Maybe the TLC editing cut out the important bits? Are the tapes any better in this respect?

-- Dan Hollis (goemon@blort.invalid), January 08, 2001.