Laminar Nozzle Cutter Test 2

11 04 2009

The cutter is working much better since I added the baffle.  The baffle is working almost perfectly except for that pesky leak.  I’m pretty sure that leak is comming from the brass nozzle/plexiglass interface. I suppose that I will just add some more expoxy and hope that it works this time.

Here are a couple of my thoughts regarding the cutter.

1. Fix the electronic switching so that it flips the electricity from one solenoid to the other immediately.

2. Fix the drip.

3. Fix the drain for the water.  I think it is probably the biggest of the three right now in order to make the cutter work properly.


Laminar Nozzle Speed Cutting Test

11 04 2009

A friend of mine posted a video of his cutter just cutting so that we could gauge the speed of his cutting.  I’ve decided to do the same.  If you have done this let me know how your’s compares.  If you have any concerns or possible design improvements let me know.  I’ve been told that this is the trickest part of the whole laminar fountain, and it is pretty tricky to get it to work the way I dream it.

Laminar Nozzle Cutter Mechanism Test 1

8 04 2009

I got a prototype working last night for the cutter mechanism!  It works….mostly.  There are some bugs in that I have to work out, but all in all a strong showing.

It may be difficult to see, but when it is un-cut there are more blurbs (I don’t know what to call it!  If you have a good name submit it please!) than there should be.  I’m thinking it is probably from the water splashing on the upper plate and then dripping down onto the nozzle and then getting sucked up by the stream casuing the annomally (there’s a good word for it).  That’s my guess.  Any suggestions as to what it is would be greatly appreciated.

Laminar Nozzle 8″ Prototype Test 1

3 04 2009

Let me know what you think!!!!  Have any suggestions?  Have you built one of these before?  Are you going to build one?  Please leave a comment.

Trebuchet – The design

22 10 2008

Ok, so last night I couldn’t sleep.  So I decided to go work on the trebuchet design.  This is where I currently am in the design process.  I would say that the model is about 90% complete.

The biggest thing that is is missing in the hook for the tip of the trebuchet, and the sling.  I probably won’t model the sling since it can be difficult to model fabrics in CAD packages.

Trebuchets are pretty simple in there design. It wasn’t really all that difficult to model, just time consumming since there were a lot of 2×4’s that I had to model.


The model accuracy could be better.  I glossed over some things for simplicity in my model.  For example the trough is an “ideal trough.”  I designed it as a one piece extrusion.  Obviously that’s not how I am going to build it but is good enough for a model.

Hook needs to be designed

Sling could be modeled.

Other Resources

Trebuchet Design

Cement Blocks


Sizing the Axle (Part 1)

Sizing the Axle (Part 2)


Car Throwing Trebuchet

Cool Trebuchet Pictures

The bucket

Trebuchet – The Bucket

14 10 2008

The BucketSo as I mentioned before I’ve enlisted some help from my friends since this project is bigger than me!  I might be able to do all of this on my own but it would take 5 years to finish instead of 5 weeks.   Sir Prichart Jefferson Hunt welded up this AWESOME metal box known as the The Bucket!

The bucket is is one of the most important parts of a trebuchet!    It has to be very sturdy since this is going to be holding about 600 lbs of concrete.  Not only does it have to hold the concrete, but it also has to swing it around, generating about 2100 lbs of force.  The concrete blocks that I am making will fit into this bucket.  I’ve only made one concrete block and I suspect that we will need about 3 – 4 block.

Compressed Air Rockets – The Physics Behind the Flight

3 10 2008

I’ve been thinking about how the rockets work and which forces are involved in making the fly.  After some help from Will, Matt, Ben, and Blake, I was finally able to come to the equation that governs the flight of the paper rockets.

h = (P.rocket – P.atm)*A*x/(m*g)    eq. 1

h = height of the rocket

P.rocket = Pressure of the rocket inside or the pressure of the rocket launcher compressed air tank

P.atm = Pressure of the atmosphere

A = Cross-section of the rocket body (not the fins)

x = the length of the rocket body that is in contact with the launch tube

m = mass of the rocket

g = gravity

  • Note 1 – m*g = Weight,  So for those working in English units you just way your rocket and subsitute it for the m*g term.
  • Note 2 – make sure that your units are consistant.  NASA has made catastrophic errors and lost millions of dollars due to conversion errors don’t let this happen to you!  =)

Using the equation

In order to keep things simple I added in a conversion factor so that the answer will be in feet after you plug in the values. The equation then becomes

h = (P.rocket – 14.7)*A*x/(12*W)    eq.2


h =(ft) height of the rocket

P.rocket = (Psi) Pressure of the rocket inside or the pressure of the rocket launcher compressed air tank

14.7 psi = (Psi) Pressure of the atmosphere (@sea level)

A = (in^2) Cross-section of the rocket body (not the fins) = (π*d^2)/4

x = (in) the length of the rocket body that is in contact with the launch tube

W = (lbs) weight of the rocket


I’d run through some calculations but I need a digital scale that is small enough to measure the rocket.  I’d suggest buying one that has the capability to measure in grams because you will be a better resolution.  Then you can convert it over to pounds.

More to come!