Engineering Project Help Please!! Need Creative Minds!!

you have quite few good answers points,

I had loved doing these types of projects in college, exercising one's imagination and organization skills, as will as sales (selling the idea to the design group)

you must be a student who will take part in a competetion of some organization. ok

but we dont know, how far is the farest idstance?

how much is the most weight?

if my mind read is right, you can use a long, as long as you can find or construct ramp, put the device your designed on the top of the ramp, take the advantage of gravition, the device will slide(roll) as long as it can along the slope surface with it wheels.(of cause dont forget to add wheels on it)

You need to convert potential energy to kinetic energy. How many ways can you think of to store potential engery.

Chemical (gasoline is out, how bout a chemical reaction that heats water or creates gases?)

Height

Mechanical (clock work spring)

Pnumatic (compressed air)

Hydraulic (moving liquid under pressure or at height)

Electricro chemical- against the rules

Heat

or combinations of the above. Sounds like with your rulest that a mechanical system or something that moves from a height to create kinetic energy would be the best approach. Although pnumatics has some good attributes going for it...

ok well sorry for the lack of information, but the maximum distance is 250 ft. so any farther than that doesnt matter, and the max weight is 50 lbs.

Also for the other idea, we have a set course that is a smooth level runway, so no ramp is allowed.

Now i do have an idea, i was just seein what other people would say without my biased idea, but i was orignally thinking that i would start off the run springloaded, such that i would roll it backwards to its max point and set it loose and then have a couple CO2 cannister rigged attached to a string that will set it loose at about like 75ft and possibly another at like 175, so it will be a sort of mid run turbo, and keep a somewhat steady speed throughout. What do you guys think about the idea? any criticism or new ideas would be great!

Try the Roman methods of catapulting technology.

The trebuchet. Brilliant!

I thought about permanent magnets without using electricity, but then you'd be getting into perpetual motion...

yea i understand where your coming from, im just not sure if you'll get enough energy through using the potential energy of water...

but the formula is http://i128.photobucket.com/albums/p176/rcman12589/proje.jpg

its meant to be able to balance out both sides, but if you notice anything please let me know. and thanks again for all your help

Sorry, I am at work on an offshore platform, so my only internet access is the company network and the company blocks photobucket. So I can't go there. Any way you could copy it into a post?

Hello Steve S. and others who cannot access Photobucket.

Here is the Performance Score Formula given by Guest in Post #7 above.

Apologies the picture is not a clear as the original Photobucket version.

Kind Regards....

Can't quite read that:-

I think the final term is (0.4d)^½ , but what is the square bracketed term raised to the power of?

here it is. how do you think abou it.

How to get this formula? it has no speed term. so we will dont know how fast the devce run?

the eqation aranged by me is a veriable mass (water in the tank) dff.Eq.

speed does'nt matter,

distance does

yes?

I think both speed and distance are all important. no speed, there is no distance in a certain time.

Im still waiting for induce procedure.

Here's your answer: Your score is inversely proportional to the Weight of the "unloaded vehicle". Simply look for ways to make your vehicle weigh approach zero. It can be done. Tell me what you come up with.

the vechicle is forward drived by spring, bow and water in the tank on it.

lets say water, it flow from the hole. mark the preset level, in order that it will stop autoly when at the score.

we can use Bernulli law to get the water drop time and then momentum law to get the vehicle forward speed. so that we can get the distance.

any fresh student in a college can work out I believe.

Dear cnpower,

Even with an arrow to give initial forward motion, what will induce the water flowing out, no matter how hih a column or quantity of water, to provide forward motion ? I suspect it will simply fall to the ground in accordance with the Law of Gravity.

If you make a rearward facing nozzle the water will exit rearwards in a downwards arc. Newtons laws of inform us that action and reaction are equal and opposite. Thus as the water goes backwards the vehicle will be pushed forwards.
Can I assume you have never held a hose pipe when it was turned on full and noticed the reaction, or watched one snake about on the grass if it isn't held?

Presumably when you urinate (assuming you are a man) you will notice the stream doesn't go straight down?

Del

Dear Guest

what is gravity law? could you write out? what direction does it fall down? because I certainly believe it s stable.

#29 said:

Simply look for ways to make your vehicle weigh approach zero.

which way? in spce shutter in the space orbit?

you recommend wind, how will you do if there is no wind in the competition site?

what will induce the water flowing out

do you know what is liquid pressure? what is relationship betwwen it and deepth of liquid(water here)

what will induce the water flowing out, no matter how hih a column or quantity of water, to provide forward motion

you hvnt learnt the law of momentum?

if you dont know center of mass, the wind you recommand will blow your car upset down. no matter how much money you will spend.

Engineers get so focused on technical solutions. A creative solution exists that will give you the maximum points regardless of how you propel the vehicle. How is the"Unloaded Vehicle weight" determined?

dont conside the wind energy, because probably no wind in the site. read above threads, I think the clock roller spring is a bet bet.dismental one old clock spring as your power. did you play toy machenism bus? that is. it will offer the power. beside you can assemble a higher tank of water and drill a small hole so that the water can flow out, according to the third law of newton. its also a power of forward.use a switcher, when the level is lower than the weight you preset. the issue is your vehicle is too small to carry much water.

Strips of tyre inner tube can store plenty of energy.

Del

use your tyre as a bow, and this device as a arrow, out the arrow fly when command is shout out.

Looking at the rules, it seems a steam engine with solid fuel burner is allowed.

Yeah, if time and material allows, a small system in a closed loop vapor heated by a candle like those small vapor engines models would do great.

But you could also use a device that is pushed down by the water reservoir weight and direct this force to the wheels. More water, more power available. No water loss.

Thought about that John... a pellet burner used to make steam... only the pellets would have to be gravity fed... no electricity... He may have to carry a water load, but there is no reason that he cannot have a water fuel source (seperate from load) used to create steam. Of course it will take time to get the power plant running (to build up a head of steam). I did not look that close at the "winning" equation, but he might be able to use the "load" to generate the steam in itself.

Bill

My OOPS. Pellets require forced air to really burn, thus implies electricity.

Bill

Could use e.g. this stuff:

"Made of premium wax and kiln dried hardwood sawdust "

or the solid fuel tablets sold for model steam engines.

Engine only needs a bit of steam - don't need to superheat it.

Looks as if the rules could be stretched to allow LPG, but it would be a good idea to get clarification from the organizers, as this opens up a load more possibilities.

I guess teams of kittens in Hamster-Balls is out of the question.

Perhaps a flywheel could be used - if spun up to speed beforehand, you could trundle your vehicle up to the start line looking all calm and relaxed. Whatever you do, minimizing the rolling resistance will probably be important.

Del has hit the nail on the head.

Using a continuous strip of joined bicycle tyre tubes or similar, longest length to fit the box dimension limits, when rolled in tension like a clock spring would give maximum potential energy to volume ratio.

It could be one or several, either in simultaneous expansion or sequentially activated but the mechanism for this would take up valuable space.

2 flywheels, 1 each side of the driving band would be ideal and these could be flywheels filled with water to maximise the project criteria.

Something like this;

what scale do you use in your painting?

How about a steam engine? Steam eninges are very strong but take a long time to heat up. Use iron rust and aluminum as fuel to heat the water. But watch out, that stuff, once ignited will burn hot enough to melt steel. It does not explode, but controling it may be a little hard. Too much steam could explode so you would need a good "Watts" regulator.

Are you a student? If so where?

Get a stirling engine and have your 2'x2'x4' tank full of very hot water and use the heat from that water to run the engine with ambient air as the "cool" part for the engine.

At the end, your water will be cooler by the amount of energy extracted. You will need to find someone with an engine that can run at that fairly low temperature differential, but they are around.

Zero weight loss during the event, no deposits on the track and a HUGE water delivery for the bonus points.

A Stirling engine drive would be very cool.. GA!!

yea i like the idea, but the only problem is that they give me water at the site so theres no way to make sure its extremely hot, most likely its just going to be coming out of a hose, so that may not work.

And for the other question yea im a student at University of Central Florida

Take the cue from the Compressed -air- driven car.

http://www.gizmag.com/go/3523/

mm

Am I missing something here or is there some other reason why the most obvious solution has not been suggested - what is wrong with the idea of using the 50lbs of water as a gravitational mass driving a gear system to the wheels to drive it over 250'? You have been allowed 2' x 2' x 4', so the machine could be 2' square with a 50lb water weight 4' high to start with. reducing to 1' high at the end of the run. It might need a little 'prod' to start it but should keep rolling to the end if designed well enough.

Cheers,

Pete.

hmm, i really like that idea and thought about it, but do you really think it'll go the 250' with just that energy alone?

I've been thinking about that and have come up with the following: If you used 8" pram wheels you will go about 2'1" for every rotation. If you had a shaft of 1/2" diameter you would need about 1 1/2" for each revolution if you used a 'string' drive on the axle. That means a piece of string 180" long compared to a weight drop of about 3', so a ratio of about 60:1. I think it might just work so long as you don't lose too much friction on your axles and drive sheaves on the string 'multiplier'.

Pete.

I think BigPete has got it about right. 50 lbs is less than 1 cubic foot so a 3 foot drop is not unreasonable here. I think I'd put the water in a plastic wine/sherry/beer container (polypin), and hang it over a small pulley with a thin cord. Allow the cord to disengage at the gear/axle end at the end of the drop so that the cart can free wheel for as far as possible.

They built something like that on Scrapheap Challenge...but they increased the thrust by pumping the water out with a couple of BIG pumps... it worked fine..
Shame it was competing against a jet engine made from a turbocharger

Of course you gould increae the power available by mounting the water tank on a nice high structure.

Del

The OP said in he initial post that the water cannot be used to propel the vehicle

If you are allowed to store energy I would likely see how to make a flywheel fit into the rules. If you take a finely balanced wheel made of dense material; wrap it with a few plies of unidirectional carbon fiber you can build up enormous amounts of kinetic energy without fear of disintegration.

I'd be inclined to get it spinning with an external compressed air source. Once at speed, disconnect the air source and engage the flywheel though a twin reverse conical reduction system. Friction types are limited in the amount of power they can transmit but they are infinitely variable over their operating range.

You'll want that flywheel to be mounted as low as possible so that the CG shift doesn't tip the machine back when the power is engaged. Or, at the risk of complicating things, figure out some way of applying all the energy over several seconds.

L.J.

i do like both of your ideas, however, the flywheel system seems like it might be a bit too complex for such a design of just going 250'. i think i've narrowed it down to using the waters potential energy dropping down 3', and using a combination of a spring loaded start up and compressed CO2 tanks for turbo throughout the run. What do you guys think? should i be considering other ideas, or are those two solid techniques.

Remember when doing your calculations, the drop of the centre of mass of the water will only be 2'

By far the best approach. And you can increase the water drop and amount as you wish. If its a plane course, no critical problems on vehicle tilting.

Stick to one idea! Keep it simple.

a pair of 4' CO2 cylinders to act like rockets.. standard 40 gal bottles at 4400 psi... could break the sound barrier..

I'm reaching out into the air on this. Look at the latest Discovery magazine. There is an article concerning a proptotype sail attached to ships by a 1,000 ft line to catch winds. The sail is shaped like a parasail. The company might sponsor you with one of these sails. dave@heatsmarter.com

wind

There is no time limit on this, so, if you do want to use wind: you could put a Savonius rotor (or any other vertical axis rotor) on top of the cart and gear it down dramatically to the axle. As long as you get some wind the cart will eventually get there and you will not need to supply any power (not even the potential height energy of the water).

2' x 4' Long Capped Pipe - water filled.

Opposing jets on one or both ends of the pipe create rotation, which efficiently rolls the pipe (and water) across the course.

Use CO2 or other "rocket" engines to drive the rotation.

simplest form of energy = gravity

simplest and most effective water containment is a membrane sphere

fill the sphere with water... roll it down the hill.

done

(2) 2' diameter spheres could fit in the limited volume of 2' x 2' x 4'- but even (2) spheres would sacrafice much potential water volume.

while true, it also true that boxes don't roll very well. Maybe a compromise could be a cylinder.

This plan does not expend any of the water to move; requires no engine, mounts, fuel, or other extra weight. It satisfies the requirements of the most water moved, by the simplest vehicle. If steering is a problem, then a V-ridge and groove could keep it running in a track, without adding much weight to the sphere/cylinder.

I saw some one had proposed water. They were using gravity as your force. What about a trusty water rocket. It is a kids toy that you can get at most toy stores. What you do is fill the tank about 1/3 and then you pump it up with compressed air. You can get some ficked heights out of one and that is only with the little hand pump that comes with it. If you were to use your CO2 idea then you could get some real acceration. You use the CO2 to pressurize the tank, becareful with CO2 you could get some pretty high pressures. I have seen a CO2 water rocket somewhere but it's been a long time ago.

You could use the prssurized tank any number of ways. The rocket idea is one with the nozzle pointed out the back. You might also try a water wheel, direct the nozzle into the paddles of the water wheel, which turns gears that turns the wheels. The good thing about this plan would be gearing. You can gear it to the required speed and torque. You might need more then one tank maybe a water wheel with rocket assisit.

Well good luck with your project.

Do you know what the track surface is going to be like (grass, tarmac, polished wood etc)?

I would suggest a cryo jet using N2 (liquid) or CO2 (solid).

The CO2 might be the simple way.

You can also combine the water tank idea. You can use the cryo to start the system rolling then have the water drop take over.

If you are going to use rolling stock, I suggest skate board bearings (good ones), hard wheels. Keep track of the rotation mass.

A second way would be to use a fly wheel. Spin it up by cryo jet, then let the fly wheel drive the system.

Will there be sun available for this demonstration? If so, please consider using a small solar chip to power an electromagnetically suspended/ repulsed spindle developing current through the spin and magnets. There is a fine YouTube experimental video demonstrating this principle that might help you develop even more practical applications. So long as the sun is shining during the contest, you would be able to go as far as you wish and with weight limited by the displacement.

Please post your results and decisions to the thread.

Thanks,

HS

Another question. Does the source of energy have to come from on-board supply, or can it be external. ie, can you electrify a railroad track, and have the carriage run by electric motor, maglev, etc?

chris

The OP stated: "... However the rules are that you may not use any form of electrical devices whatsoever ..."

Slowpoke made a very good point. Look at and use the points system. It is fun to try to build the ultimate. But, in the real world engineers usually have many time and budget issues that force you to be realistic rather than "Great". The instructor/prof of a school project will usually try to make you think about the real world at some time in the project.

Brainstorm from the cheapest, single mode concept all the way up to an complex system with multiple functions. Sketch out block diagrams and pro/con lists for many systems. Then look at your time budget, your money budget and the manner in which you will be judged to be a success or failure. In a good school project you will probably go back and forth with many ideas, settle on a SIMPLE but VERY WELL BUILT project and after some hard work still be able to go out for pizza on Saturday afternoon.

A really great system that has many complex features but doesn't perform due to its complexity will get you a low grade. A simple system that meets the project specifications will get you a very good grade. You are brainstorming to be great. You are building the project to get the grade.

Most of the suggestions attack the problem of converting PE to KE. (Agreed this is the primary problem.)

Some of the suggestions recommend energy storage devices such as flywheels. The problem with a flywheel system is that there is a loss associated with changing one form of PE (spring or gravity) to another type of PE (rotation). If a flywheel is to be employed, its primary function would be to regulate energy conversion so that wheels do not slip due to rapid acceleration. The ideal system performs only one energy conversion which is controlled (not released all at once) so that the energy is converted as it is needed.

Efficiency of energy conversion is extremely important on a project like this. Any engine which blasts a gas through a nozzle for propulsion will be improved if it is controlled. I recommend taking a close look at bottle rocket technology. There is a wealth of knowledge out there on the internet.

A very simple, high efficient, old technology system is a simple model airplane propeller and with a rubber band motor.

Friction needs to be carefully managed. Large diameter hard wheels provide the least rolling friction. Also, do not provide a suspension which softens the ride but absorbs and wastes momentum energy. Wind friction at these low speeds is only a minor problem. Just make sure that the vehicle surface presented to the motion of travel is slightly sloped or curved.

Energy conversion from rotation motion to linear motion requires a high coefficient of friction between the wheels and the running surface. Factors for good traction such as applied downward force (weight), tire material, and surface contact area are difficult to optimize as two (running surface condition & contaminants on the surface) of the three factors in the tribology problem cannot be controlled. Moisture, sand, dust, oil, wax, etc. between the tires and the running surface all work to reduce traction and may be different on the day of competition than on the day the system was optimized. Whatever you do to improve traction to get the vehicle rolling will also work to slow the vehicle down.

Because of the difficulty of managing traction between a wheel and the rolling surface, you will find that propulsion through nozzle or propeller are hard to beat.

Motion stability is another factor to consider. Shifting mass in a vehicle can be tricky. Especially if it is a liquid which can slosh around. You may find it best to just contain the liquid in a fully filled container.

Best of luck. Please report back on the contest results.

When is your project due?

The rules as we have been shown, appear to allow you to be on the transportation device and push forward via the wheels or pull on a rope. Of course, providing you fit the 4x2x2 volume envelope and you are not an animal.

Is this allowed ?

Only if you're very small.

When is the project due? And is it a team project or individual project? Are you permitted to inquire of outside sources? I think this is a creative solution. If you were in the working world, every source is fair game.

I did some calculations to see what we were up against.

If the start and final water weight was 50 lbs. and the vehicle weighed 100 lbs. it would have to travel 41 ft to get full credit (150 pts.)

Since the empty vehicle would probably weigh much less than 100 lbs. I'd keep this as simple as possible (less to go wrong).

Someone suggested (I think) a rubber band (inner tube maybe) with one end fixed to the chassis and the other end wrapped around the drive axle. Very simple. I'd attach the rubber band to the axle so that it it would come off the axle when it runs out.

Good luck.

It would be an idea to review THIS thread which was on a similar topic and has some good suff, including a car driven by rubber power!

Del

Input Questions:

The energy to move the water has to come from somewhere. Apparently, the water load itself is not allowed. I'm not sure if that means that the volume of water is not allowed to change, or what? Because the gravity systems, to roll down a hill, or to drive gear reduction, is still using the water as a source of energy.

If the energy is not allowed to come from outside of the vehicle envelope, then it must come from inside, and then you are dealing with some form of stored energy, either as a fuel, or other forms of energy storage. (flywheel, compressed gas, spring, chemical reaction, etc)

One thing is sure... the water won't move on it's own. We need to know what the restrictions on the energy source are, more specifically than we now know.

chris

I would like to draw this, unfortunately do not have the time tonight
perhaps tomorrow - but I will try to describe a "picture" of it.

Imagine 2 sealed containers, upper and lower. The water is initially
put in the upper container and is released through a variable valve
(shielded jet) into the lower container, safely keeping the water.

The upper container is pre-pressurised either by pump, cylinders of gas,
or, preferably, a large spring loaded piston in a tube. (eg similar to air rifle)

The (highly) pressurised, small, jet of water is used to drive a "pelton" style
wheel for the rotary motion, which is applied as a direct drive to the
wheels of the contraption. (we have motion, and not too many losses)

As there are no obstructions, eg hills, etc. no gear changes are needed,
and, the speed can be adjusted by varying the opening of the variable jet.
This ensures the "vehicle" reaches the 250ft limit; probably at a fast speed!

There are only 2 moving parts, the spring loaded piston (for air pressure)
and the "pelton" style wheel for the direct drive. It would go like a rocket!

I hope this helps. (sorry no pic.)

jt.

My beautiful gold pocket watch; it belonged to my grandfather, and,
on his death bed, he sold me this watch.

you take so much tme to draw a so much beautiful picture, why not vote?

I vote this as a good answer.

which software are yoiu using and how long did you take?

solidworks.. 2 hours.. most of that on the v-belt.. I had the idea before I started though.

I added the labels to the screenshots in paint.

I'm not sure what you mean about voting.. I can't vote for myself?

now that the new specs are out, I'm going to start over..lol

just for fun.

Good Job chris!

if were me, I would take about, at least two weeeks. thats why I admire and vote

how do you draw the v-belt?

A new thought to get compressed gas to run the device. Again keeping with a tank of maximum suitable volume. Have the tank sealed with some head space and a device to drop in DRY ICE as the fuel (creates gas at high pressure as result of heat exchange with the water) and then use that pressurised gas to run a suitable motor. Only weight loss over the course is the gas expelled through the motor.

After one or two trial runs, you will know exactly how much ice to use to get whatever distance you want.

Pressurize the water tank with a small CO2 cyllender and have that water drive the machine? Screw drive? Some other form of drive that will use water under pressure?

I suggest putting the water in a large piston and adding alka-seltzer to create co2 pressure. The combination of water weight pulling down and air pressure pushing up through A simple pulley to gear/string Is the forward power. Little added weight, so distance need to move is small.

A block of dry ice in the water would do the same thing.

you could also use dry ice to cool either side of a Stirling engine.

The air pressure created could also run a small air motor. An air motor would add weight.

You say in your original post: You can not use the water weight for any fuel You are penalized for any weight that is lost throughout the run, so I cannot leave objects on the track, however if my design burns or uses something else up then it will not count against me — Can you clarify this: You are penalized for any lost weight, leaving residue on track etc. but if you burn something or use something up it will not count against you. Is the original "guest" Author still monitoring this thread?