HardWired II

[overkill]

its just about impossible to calculate the amount of battery capacity required as there are so many variables. Most people look at equivalent designs and use whatever worked for other builders, while others build the bot and test it to find the battery capacity required.

Having a look at other designs, Archangel's bar is heavier and almost 3 times the RPM of Scissorhands, which uses up most of a 4.2AH, 6S pack during a full length match. NST might be another example to extrapolate from. Given the much higher speed and KE of Archangel's bar, my guess is that its going to need somewhere between 2 and 4 times my battery capacity. Its beginning to look like there is a lightweight class weapon being squeezed into a featherweight ...

[maddox10]

Don't worry, Valkiri 2 uses a 4S 8000mAh pack, and is 2 kg underweight.
The 3 kg 395mm disk ain't somthing to sneeze at.

[overkill]

Have you calculated the MOI and measured the RPM of the disk? That battery pack holds 118 watt-hours of energy and could be a great baseline for Matt to work out his battery size.

[maddox10]

I use gut feeling. And it seems to work.

[overkill]

Fair enough - I like doing the maths. Numbers are really cheap and don't catch fire

[Revsmin]

If you take.Archangels base and make it 3mm Ti instead of 3mm stainless you save all the weight you need for a bigger battery.

[overkill]

Wouldn't that make it harder to join the base to the side armour? There's no chance of welding it and screwing it together adds weight and is weaker. How about staying with steel and adding some cut-outs where strength isn't important?

[Flag Captured]

They do if you're me, Nick! That picture of Homer Simpson with the breakfast cereal on fire springs to mind...

Whichever way, it sounds like I'm going to need a pretty beefy battery pack which probably points towards me needing a lower voltage motor so I can get a bigger capacity for the same weight, if that makes sense?
Been having a few chats and the NTMs may be a way forward, specifically the 5050/5060 on 6s... I wouldn't be able to get as high a reduction in to get that 7k I'm wanting, but I've heard good things about the torque on them... at the very least it's worth a shot!

I may look at that too Jarvis, thanks! I was looking at making the bulkheads a little stronger instead and just going for a thin ti base instead, but I'll see how it goes probably. I'll need to do plenty of adjustments to the design but nothing particularly major I reckon, just adjustments on the bulkheads themselves!

[Ellis]

NTMs may be a way forward, specifically the 5050/5060 on 6s...
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I was looking at making the bulkheads a little stronger instead and just going for a thin ti base

These both sound like good things to me! You can always upgrade should a cheap brushless setup not suffice, but I think it will and if it does you've saved about a billion pounds.

[Flag Captured]

Certainly! For one it's a lot cheaper, and that means spares are easier to come across for when the inevitable happens...
Bulkhead wise I'm only using 6082, not Alumec or anything like I initially planned to use for cost purposes so the chunkier the better! Would ideally like 20mm solid ones but that'll be extremely heavy I'd imagine so probably not the best plan, I'm not sure!

Probably need to Cad it up again with the adjustments and see what the weight comes out at, probably.