Since we couldn't make it up to Antfreeze, I spent the weekend messing around in the workshop. As well as getting my first fleaweight spinner just about done (details to follow in due course), been having lots of fun with the flail...
Those who saw it at the Basingstoke Open or at AWS60 may recall that "Tray Again, Flail Again, Flail Better" (TAFA) has a tendency to throw itself into the pit immediately after striking an opponent. Always been the plan to replace the flat blade with some kind of propeller that would give a bit of down-force to help mitigate this lemming-tendency. Unfortunately I couldn't figure out how to get this precise enough using the 1mm titanium sheet, nor how to stop it flexing. Moreover, that original blade was a pig to make and I didn't fancy having to do it all again to make spares - though after losing the weight off one end in a fight at AWS60, I knew spares were needed. So... half an hour's clumsy mucking about in Fusion 360, two hours on the printer, a bit of tinkering... and now I have the first prototype 'downforcer' blade for TAFA;
Instead of the 90lb trace wire I used before I've gone for the 275lb - still v thin and light but grips much better with the size of dbl-barrel crimps I have handy.
The design of the aerofoil profile is going to have to be trial and error but this was my starting point. Printed using my new favourite filament; PolyMax PC.
Old vs New - figuring out a way of clamping the flail wire on the old design was a nightmare. In the ends i used a tiny offcut of titanium with a couple of m2 machine screws and nyloc nuts. With the new wing it's a piece of cake; to make the flail arm strong enough, I have a length of stainless steel capillary tubing running through the middle of the blade. By making this tubing slightly longer than the blade, I can simply crimp the ends to stop the wire sliding through:
As before, the business ends of the flail are tungsten 'bullet' fishing weights, secured by passing the wire through the weight, through an m2 nut, then back through the weight and securing with a double barrel crimp. Currently just using 2g weights at each end but I think I may now be able to get away with using the 5g size, to give it a bit more 'oomph':
So does it work? Well, I put TAFA on my scales, retreated to a safe distance and ran it up to 3,000rpm (measured using a cheap optical tachometer), which seems to be the 'comfortable' speed. Results not spectacular - initial test design only gave an extra downforce of around 4-5g but if I can get that above 10g I'll be happy. What I hadn't anticipated though was that it now runs a lot more smoothly - possibly because the old flat-wing design would have suffered from vibration-inducing turbulence/vortex-shedding issues. With an effective diameter of 28cm and running at 3,000rpm, the end-weights are travelling at just under 100mph, which I reckon should be ample, especially if I can get it running smoothly with 5g weights.
Lots of work to do before it's ready for AWS61. Need to optimise the 'wing', experiment with flail wire length and weights, redesign the body a bit (and finally sort out an accessible battery compartment that doesn't involve gaffer tape). Also plan to add a more 'springy' front support for it to rest on as I found that made a huge difference to the vibration problems with Recycler (currently just sits on the two ToughHub wheels and a button-head screw in the middle at the front). Might even be able to free up enough space/weight to use a 3S LiPo (the electronics were designed for it but I had to drop down to 2S to get below 150g). Watch this space!
Meanwhile, here it is in action against an old Recycler body-shell (~25g):
TAFA test (Youtube)
Obviously the results won't be as spectacular against a 150g opponent, especially one with angled sides but it should at least be an improvement. I don't expect a flail will ever win an AWS event but I still enjoy the 'disruptive' aspect of the design!
