Random orbit 2 – The second coming

b68814ddfa8520c9ffb976e0af494753It started with an innocent enough conversation along the lines of “You know Andy, most people with a TZR have a bigger duct”… “Do they? (quick look round) Oh yes.”.

Out with the angle grinder.

Random Orbit version 1 had a 750mm duct and putting 45bhp through that is a bit of a tall order and so I decided to put a bigger duct on. I’d also heard that some time earlier, someone had put a lift duct on a Cyclone and raced it in F1.

I decided I’d have a go at putting a 900mm thrust fan and a lift fan on Random Orbit.

The rules in F3 say that you can run any number of two-stroke engines in any combination up to a maximuim of 250cc but it’s tricky finding a good combination to give lift and thrust so I decided to try a shaft drive.

[note. I’m writing this in 2008 and shaft drive craft are all over the place but when I did this job in 2001ish they were quite rare]

A shaft drive means you can get the advantages of twin ducts on a single engined craft but designing one does make things interesting.

A big note… I didn’t take nearly enough photos and without them it all seems a bit dry so this section is very short.