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Using one shot CO2 cylinders as a propulsion system the F1 challenge seeks to pit teams against each other in side by side races.

In each race both cartridges are pierced by a firing system and as the high pressure liquid Carbon Dioxide vents to atmosphere the jet effect propels the cars down the track.

There are two main styles of car used within the challenge the first or D-Type was originated in america and supported by PITSCO education and was not originally locked into CNC manufacture.

The Dtype is now known as the Bloodhound Challenge.

 

Dtype

 

The D-Type Co2 racing car is manufactured from a single piece of balsa wood sized to this diagram.

Balsa

 

It is worth pointing out that in my experience the level of variance in the blocks is noticeable and there seems to be very little if any spare for machining.

To that end it is important to ensure that the design does not exceed the parameters of the block. We have included a Pro-Desktop block as part of this section to allow students to work in a subtractive manner that ensures their car will machine correctly.

 

 

Furthermore whilst machining it is important that the hole that is to accommodate the cartridge is not machined into, both to preserve the support mandrel and also keep inside the competition rules which require a minimum wall thickness of 3mm round the outside of the hole.

It is worth making sure you are familiar with all the rules as some may restrict your design choices.

 

The dragster type design.

Dtype

Dtype Design - In Pro Desktop.

Dtype Design as an STL file.

Shown here is included as a download should you find you are short of time to design your own classroom example. If you do wish to alter the design you will also need C02Jig and Spigot files available just a little further down the page,
 

The Co2 Jig is designed to ensure that the car is correctly oriented within the virtual block.

If as part of the design process the student has lowered the roof height to its minimum the overall block size for the stl may no longer be 70mm the net result being that the software would automatically centre the new stl file inside the virtual block whilst the real block is now underneath the stl file. resulting in heavy machining on the base and the model standing partially in fresh air. due to the actual block tapering away to 20mm.

If a solid block was used then this problem would not arise and the car would be machined at the new height but still inside the block.

Unfortunately the taper means that the STL file needs to be held down to the bottom of the block by ensuring that the cartridge hole is in the correct position.

The next video shows you how to attach the Co2 Jig to your drawing.

New Co2Jig Download Pro-Desktop - NewC02Jig

Support Spiggot Download Pro-Desktop - Spigot

 

Co2 Jig Attachment Video.

Now that you have placed your car inside the block it is worth checking one final aspect of the design.

When designing a vehicle with reduced drag the temptation is to finish the bonnet in a knife edge. Now whilst this is good aerodynamic design. Machining requires that both ends are held sufficiently well to ensure good machining characteristics.

Thus if the front end nearest the chuck is whittled away to nothing no support will be given by the chuck for machining and the car will fall away.

The spigot is intended to be added to the car in the same way that the jig was added but to provide a little extra support at the nose end.

 

Now we are ready to manufacture this is covered in the following written tutorial.
Co2 Machining Tutorial.
Additional Reference Material

Pro Desktop Car From Tutorial - Download File

Other Dtype

STL Version of Tutorial Car . . .Download File