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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.

 

Rtype

 

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

Balsa Details

 

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.

 

Block

Block Download - Pro Desktop

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 Rtype Design type design.

R Type

Shown here this design 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. Please note this car does not comply with all the rules.
Rtype Design - In Pro Desktop.

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 50mm 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 machining on the base and the subsequent loss of the safety wire groove.

RTtype Design as an STL file.

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

 

Unfortunately the slot 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.

Spigot

Co2 Jig Attachment Video. This video works for both car types but ensure you use the correct Jig.
 

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. It is also important that you ensure you have the Rtype jaws available for fitting to your rotary attachment.

 

Rtype Finished

 

R Type Co2 Machining Tutorial.