Intro: Pnewmohudralic Jet Machine Marklar 3
Jet powered machines always more interesting than regular vehicle. So I
decided to create fun toy, with jet engine.
You can make this, for playing with kids and explain them how jet powered machines move.
This jet tricycle have interesting jet engine, it nice demonstration of working jet engine, and, which as for me more important, it shows depends between speed, weight and energy. And first of all it's simple, fun and spectacular vehicle.
Before I made this vehicle, I had made few others. First was catamaran, based on two bottles with compressed air, and one bottle, with water. It was fun, but, I want higher speed. Also I had notice, when bottle with water almost empty, and water outcome speed increasing, and vehicle too.
Obviously, this happened because speed of reactive mixture bigger than speed of water.
Also, I had made only pneumatic jet engine, and it's was not so effective.
Step 1: Some Theory
Main characteristic of jet it's impulse. Impulse it's weight multiplicities on speed. In my case, it's speed of flowing matter multiplicities on it's weight.
Vehicle with water jet had big weight of working matter, but low speed of flow (maybe because of turbulence in tube). Vehicle with air had big speed of flow, but low weight. I found compromise.
What if we can combine the good sides of air and water?
Let’s mix up.
In mixing working matter has lower density, lower weight, but bigger than in air, and bigger flows speed.
We, me and my young assistant, measured time of engine work, it's 10 seconds. During this time engine loose almost 100 grams of working matter.
My final speed calculation on photo above. Theoretical speed is 28,8 kmph.
About calculation. I suppose that 2 litters of volume just go away, like in vacuum. If I need to calculate speed of flow base on pressure of gas then I need to use molecular kinetic theory. But, in my case it's only mechanic.
Step 2: Materials and Instruments
Materials is very recycled. Recyclier can't be.
- roller wheels (borrowed, I will place them back)
- plywood from broken bead
- two straps from some chair
- plastic bottle
- two 'presta' nipples from bicycle camera
- plastic file carrier
- chlorwinil pipe
- polyvinyl acetate glue
- little peace from broken antenna, you can use any little pipe
- screw driver
Step 3: Engine
My friend sad me, you need a 3d printer. But I sad, what I would do to
So, I create little frame to combine coaxial outer and inner tube.
This frame, I build from plastic file carrier. I cut it, made 4 rectangle and glue it together with superglue. This carburetor frame must be not so big for placing into bottle.
I made two holes in frame, and placed there nipple, and pipe from antenna. Pipe from antenna must placed coaxial.
Frame I fix in bottles cork.
Pipe from antenna connected with chlorwinil pipe.
That nipples outer whole is our engine.
Step 4: Frame
I decided, that this vehicle had 3 wheels. Less wheels - less friction of
rolling. Wheels I borrowed from my roller skies, I will take them back.
Frame. Frame I build with wood from some old chair, which I found somewhere near recycle bean.
Front wheel I sat on plywood which I glued to the longitudinal bar. After that I made T-like frame. I connected wheels to frame with screws.
I glued peace of bottle holder to frame.
Step 5: Testing
Vehicle done. Experimental speed was 28.5 kmph. Calculated 28.8. I think
accuracy not bed.