700xxtreme Low Head speed...?

[Mvcg]

Hi guys, I'm trying to understand whether I can fly my Logo 700xxtreme at a low headspeed?


Im running:
4525 520KV Scorpion motor
130A Scorpion Tribunus ESC
Zippy Compact 6200mah 40C 6s lipos (x2)
Scorpion Backup Guard
stock pinion (17 teeth I believe)
MKS servos etc...


Can I run this setup:
- on 1 6s lipo?
- what head speed should I aim for?
- I understand a lower tooth pinion would be beneficial for this however havent a clue where to get one and what MOD(???) etc...
- any other tips on setup / other?


Many thanks!

[trillian]

What headspeeds are you running at now?

One of my first thoughts with the saddlebag type of battery arrangement is that you may not be able to get a proper C of G with a single 6s pack (and chances are the headspeed would be too low unless you're at a very high headspeed on 12s)

Generally speaking, around 1300-1400 is probably good low-ish range, but it's a very personal preference thing (and you may need to increase the collective range depending on what you've got now).

Mr Mel's headspeed calculator is a very good resource for seeing what throttle % yeilds a certain headspeed or what the effects of different pinions, cell count etc. MrMel headspeed calculator v3

[james_2k]

You could add ballast to counter the single pack for cg reasons i guess.

Seems a lot of guys use a single pack on their 12s setups, you get half the rpm naturally, so if you can manage 2000+ on 12s i'm sure it would be flyable on 6s @ a 1000+/-, with the caveat that you wont have the power or potentially tail performance that you have on 12s

[Mvcg]

At the moment, I've followed Mr Mels calc speeds with the 12s setup. I think I'm running 1700, 2000 and 2200 but will double check this evening.

One of my concerns is whether my Scorpion 130A ESC can handle all of this as I understand Low Head speeds stress ESC quite a bit?

[trillian]

Low headspeeds actually use massively less power. For example, to go from 1000rpm to 2000 rpm requires 4X the amount of power in watts / hp.

What would stress the ESC would be if you try to get the same power (and when I say 'power' I mean watts) on half the volts. So for example if you need 50 amps on 12s for a headspeed of 1700, you'd draw 100 amps on 6s to get 1700.

The other way some people might stress the ESC is running very low throttle - some ESCs handle that better than others.

But reducing the headspeed it's very easy to see that you can have drastically lower power requirements. Obviously you must adjust your flying style - you won't get aggressive smack performance at 1100 rpm

The most common single pack low headspeed approach that you see the 3D guys doing, is that they have it geared for something like 2000 governed on 12s, so they'll just run one pack and a jumper and bring the throttle up to 100%, so no gov headroom, but you get a bit more than half the 12s governed headspeed and the power draw is way less than half so the flight times are very good. But the result is usually a very low headspeed that requires more style adjustment. Its very easy to try though.

At the moment, I've followed Mr Mels calc speeds with the 12s setup. I think I'm running 1700, 2000 and 2200 but will double check this evening.

One of my concerns is whether my Scorpion 130A ESC can handle all of this as I understand Low Head speeds stress ESC quite a bit?

[Mvcg]

The most common single pack low headspeed approach that you see the 3D guys doing, is that they have it geared for something like 2000 governed on 12s, so they'll just run one pack and a jumper and bring the throttle up to 100%, so no gov headroom, but you get a bit more than half the 12s governed headspeed and the power draw is way less than half so the flight times are very good. But the result is usually a very low headspeed that requires more style adjustment. Its very easy to try though.

So in my case, as my setup with 12s gives me a headspeed of between 1700 and 2200, I could quite comfortably do as you've mentioned with my 130A ESC? I'm not quite sure I understand the difference between using a jumper or just plugging in one battery instead of 2?

[trillian]

Yeah, that's a very easy way to try a low headspeed without really having to change anything. If your battery serial Y lead is hard-wired on, you cannot just connect one battery, you won't have a circuit and nothing will happen, hence the jumper. If you have a single battery connector plugged into a separate serial Y lead then you can remove the Y lead and plug in a single battery.

So in my case, as my setup with 12s gives me a headspeed of between 1700 and 2200, I could quite comfortably do as you've mentioned with my 130A ESC? I'm not quite sure I understand the difference between using a jumper or just plugging in one battery instead of 2?

[Mvcg]

Super!!! Thank you trillian for all your responses!!!!