You will need
- Metal pipe welder.
Prepare a piece of a metal pipe with a diameter of 250 mm and a length of 360 mm. Both sides of the weld to her conical cap with holes in the middle. Hole in one cap with a diameter of 80 millimeters and 50 millimeters in the second. This is the combustion chamber.
Further, one side of the combustion chamber in a hole of 80 mm will Waite a piece of pipe of appropriate diameter and length of 400 mm is the nozzle. After you will need a U-shaped bent pipe, with internal diameter 50 mm. One side of the U–shaped tube with a length of 510 mm, the second side 250 millimetres and connects these sides of the middle part of the pipe is 400 mm.
The long end of the U–shaped pipe wwrite 50 mm hole of the combustion chamber, and the short end to be welded to the funnel narrow end. The dimensions of the funnel: length 1030 mm, narrow end 50 millimetres wide and 150 millimetres. The engine will have a U–shaped form. After the explosion of a mixture of fuel and air in the combustion chamber creates an area of vacuum, which immediately enters the new portion of air and fuel.
The engine can run on many fuels, but is easiest to use propane. Weld a metal tube to supply gas into the combustion chamber. For ignition of the mixture, use automotive spark plug, on which the reel is variable voltage.
Be careful of any jet engine explosive.
In operation, the engine gets very hot, even melt, so long he cannot work. But if you build a lattice enclosure around the heat-generating parts of the engine and fill the space between the housing and engine housing to more low-melting metal (copper), then the engine will not start to melt until the buffer metal to evaporate. Although this will increase the spacecraft mass and complexity of manufacturing.