How to change a 12S to 14S?

[guyguerra]

I have both a 14S Logo 800 and a 12S Logo 700. They both have the same Pyro motor and Kosmik 160 ESC. I had to rebuild the 700 and just finished. It dawns on me that I would like to change the 700 to a 14S as well. Then I can use any of my 5 14S setups, as otherwiswe they dont get used much.
What do I have to do? It seems like nothing. I am using a Demon and it doesnt use batery voltage for set up. It seems like the ESC inteligently knows how many cells are connected, and the motor is rated for 14S. Should I just plug in 2 - 7S batteries and go, or is there something Im missing?
Thanks,
Guy

[rcmarty]

Is the logo 700 motor the stock motor ?

Changing from 12-14s will cause a lower throttle curve/target on esc , pinion down is also helpful.

Stock YGE has active free wheeling so that's not an issue with low throttle curves (within reason)

Pinions on the XX are a but limited, there is some 16T out there if you look hard enough. Still not a long ways from the stock 17T

Best choice is to change the motor to a lower KV motor.

On my 14s 700XX I run a scorpion 4530-450le on the stock 17t pinon , stock 160hv YGE with 800 heatsink , and 14s 4400 65c thor packs.

Far more power for those collective (poor) management times. Rather than excessive bog it plows thru with far less bog. (I also got 14 on the pitch, not used much in flight but more for a big poke just before and auto touchdown)

Quick KV rundown :

KV of a motor is the rpm per volt applied.

EG , stock 700 motor of 520kv. 1v =520 , 2v=1040 , etc

So bumping from 12s to 14s will add (about) 8 volts on average.

8 x 520 = 4160 extra rpm on the motor shaft , into the gear ratio ( 175/17) of 10.29

You end up with another 400 rpm on the head.

I did my calcs based on the stock proven setup.

520kv x 12s (4v average) = 24960 rpm
450kv x 14s (4v average) = 25200 rpm

Very close , a few % on the throttle curve and your right back where you need to be.

Hope this helps some.

Best to change out the motor. Running deep (low) throttle curves makes for larger head speed losses , slower rpm recovery (bog) , and large amp spikes.

Just occurred to me that you might be talking of the 800 packs (14s5000) , these in the 700 would create a weight penalty , the 700 in stock form leans to the heavier disk loading , 14s5000 would increase this.

Increase flight time for the sport flier , but a penalty for the 3d guy.

Martin

[mahbouni]

Originally Posted by guyguerra

I have both a 14S Logo 800 and a 12S Logo 700. They both have the same Pyro motor and Kosmik 160 ESC

FWIW I've been running my 700xx on 14s since day 1. Pyro 800-48, 19T pinion and Kosmik 200. 5000mAh packs are too heavy for 713mm blades but 753mm or greater will easily do it. Otherwise 4400mAh would be better

[guyguerra]

Originally Posted by mahbouni

FWIW I've been running my 700xx on 14s since day 1. Pyro 800-48, 19T pinion and Kosmik 200. 5000mAh packs are too heavy for 713mm blades but 753mm or greater will easily do it. Otherwise 4400mAh would be better

I didn't think about weight. Yes, I wanted to use the 5000 mah 7S batteries that I keep for my 800. I have 5 sets and they don't get used often at all because I have so many Helis. Between the 700 and 800 I would use them much more often.
I also have a set of 800 size blades that I can put back on the 800 and put the 753's that are on the 800 on the 700.

If I run the 753 blades on the 700 will I need to lengthen the boom or increase the size of rudder blades?

Will the 700 run bad leaving 720 blades on it due to the extra weight? I won't spend more money on batteries (that's why I want the 14S, so I can use these expensive batteries more often) so if the 14S is too heavy I'll stay with12S.

Right now I plan to just do it as is. I'll check the head speed to see if it's a problem. If it is, I'll go back to the 12S setup.

Marty, you were asking about the motor and ESC, I listed it in the starting post. They are both Kontronik.
Thanks guys

[mahbouni]

Originally Posted by guyguerra

If I run the 753 blades on the 700 will I need to lengthen the boom or increase the size of rudder blades?

No. I'm running 760mm blades without issue. 116m tails too

Originally Posted by guyguerra

Will the 700 run bad leaving 720 blades on it due to the extra weight?

For me it would be too heavy but there's no 1 correct answer for everyone. Seeing as you have both size blades you might as well try both and see for yourself.

[rcmarty]

noticed the kon motor later ... I should pay more attention

scorpion / yge so common , I forget.

700 will swing 753 in stock form.

If you move the blades around this could work for you.

I'd be a little concerned about harder flights on the stock motor , might get hot and draw some big spikes.

Also worth noting that the 753's will slow cyclic down, I with there were more options in that range.

Or better yet a good set of 730's would transform the 700 into a lighter disk load.

Martin

[guyguerra]

I'll try different options tomorrow night and let you know what it does.

[mahbouni]

Originally Posted by rcmarty

Also worth noting that the 753's will slow cyclic down, I with there were more options in that range

They may not be the fastest blade in the world but they're not that slow and were good enough for Kyle Dahl to get 2nd in 3D Masters. Here's a demo video from the same event.

3D Masters 2011 mikado XXtreme Demo Kyle Dahl (4 min 10 sec)

My Rotortech 760's are quicker and I just bought a set of SAB Thunderbolt 750's to try. Got them really cheap from a fellow pilot who abandoned his Protos Max V2 project. There's also Zeal 750's. I've not tried their larger blades but I like their 285's on my Oxy 3

[rcmarty]

I might have to re-visit the larger blades as there is more option on the table now.

I have the 14s setup (recommended for 753 sticks)

Back when I was considering it I had 3 choices : edge , edge , and edge

On the other hand it flies so nice and after 275 ish flights I have figured out how to make it jump and auto to my liking

Martin

[mahbouni]

Well I tried the SAB Thunderbolt 750's today and I wasn't overly impressed. Significantly less lift and agility than my Rotortech 760's. They felt quite precise though. Exactly the opposite of what I was expecting. Back to Rotortechs unless VTX come out with some 757's