I finally found the conversation with the person who stated I would gain more flight time with a 10s set up. I will post some of the comments below, including replies from several people. Many have their own version or experiences concerning head speed and flight time. Each paragraph is a reply, this is the only way I could separate everyone's comment. It should make sense, but it's long. There are several differences in this conversation. Richard is set and confident running two 5s packs is the way to go. I highlighted the post where Richard started kicking in.
I have posted this as we touched on a likewise conversation within the last two weeks.
The subject is: What setup will give you the longest flight time on scale type helicopters. They are several good points made along with several suggestions.
See what you think! I am as well as several others are interested in hearing your reply and suggestions.
Thanks, Dennis
Well, if you want to run lower RPM then 1900 you should change the tail gear ratio to nitro's. From 4.37 (Tail Drive Gear: 22T) to 4.95 (Tail Drive Gear: 21T). This helps with any tail authority on lower rpms. How low are you trying to go and why? FYI your head is DFC.
I do not fly hard 3D, just mostly fly around casually with a few flips here and there. I just want to get as long flight time as possible. Like maybe 7 or 8 minutes maybe.
I used to run a single 6s 5000 pack on mine at around 1100 rpm with no issues. Actually went down to around 800 once and still no wobbles.
I am just a sport flyer anyways. I am just trying to get as much flight time as I can out of a 12s pack. I really don't want to go that low, maybe 1900 or so. I don't know much about flybarless or electric helis.
Same here, looking for longest scale/sport flight time. How about going down to 8s instead of 12s for 1600 rpm. Not seen much info about this setup for 700E ? Maybe 6s is more efficient (less weight) ? Thinking about trying it on a stock 510kv 112/12 setup with 710mm asymmetrical blades. I know that its not recommended to go under 90% on CC Ice Esc so pretty much impossible to do low head rpm at 12s.
Yes you could use 8s using 2 4s 5000-8000 packs. That would be a great setup for low headspeed and long flight times. With 6s you kind of NEED to only use a single pack because the HS is so low. With 8s you can have 1300+ head speed in a stock Trex 700e so you can carry more capacity.
This used to be the case when the first 800's started appearing, people would say they NEED 14s! Rubbish! I flew my Trex 800 Pro (RIP) on 10s at 1800 rpm (plenty on an 800!) using 2x 5s 8000mah packs and could get 6.5 minutes hard 3D! That's the same as I get on my 700 nitro! I could have still 3D'd it on 8s at 1500 rpm and if I could find some 4s 10000mah packs I would have done and probably got 10 minutes 3D! Actually with the drone boom there are lots of big capacity packs to be had these days.
It seem to me several are starting to run 10c packs, 2 5s packs.
6s are 22.2 volts. If you go to 5s, the voltage is reduced 3.7v, correct.
Let me know what I am missing. 5c should be 18.5 volts, correct, so hook up 2 in series, you voltage should be 37.0 volts. 37 volts is OK to run in my 800?
Your 800 will fly on anything from 6s to 12s. 10s is good because there is still plenty of head speed for aggressive 3d but longer flight times.
How do you figure going less cells is going to give longer flight times? More mah is what gives longer flight times unless I have been missing something all this time. Less cells will make it lighter, but will also give less power as well. So you tend to go with a bigger mah battery to make up the difference because you are having to use more power. As an example, when I had my Trex 600, it was using a 5000 mah 6s. The same trex 600 on 12s is a 3300 mah battery. The flight times were similar. The same example can be used on the 450 using a 6s or 3s. The 3S has more capacity, but less power and the flight times are about the same using the same head speed.
By increasing the capacity. A 6s 5000 weighs the same as 5s 6000 for example. The lower voltage naturally lowers the HS so the heli runs more efficiently plus you have more capacity in the packs so you get much longer flights. In your 600 example and if the HS's were the same the 12s 3300 should give much longer flights than the 6s 5000 because the Wh is greater in the 12s 3300. However if you ran the 6s on 6600mah at lower HS (similar idea to my 800 on 10s) you would get much longer flights on the 6s than the 12s.
Doesn't make sense, because you are running the same gearing, just less power. Since you have less power, it takes more to do the same work. On Nick Maxwell's tri-bladed raptor, he basically ran the same battery set up, but reduced his gearing and in turn reduced his head speed. That gave him more flight time. Instead of going less cells and more mah which gives you less head speed, why not just gear it down?
Not possible on a Trex 700 unless you buy a lower KV motor and even then you are still using the same capacity packs. By dropping the voltage you can carry more capacity for the same weight AND you are running slower HS's so you get MUCH longer flights and everything runs cooler.
Not less power, less voltage. Your second sentence would be true if we were increasing the gearing to get the same HS, but the gearing remains the same.
Basically, the low kv motor on 6s has very low amp draw, and removing a 5000mah pack is a significant weight savings. I haven't done the math but I saw a guy fly a 700 on a single 6s pack with a 70amp esc and the esc didn't even get warm, so the amp draw must be low.
Yes you could actually use a 40A ESC when running a 12s 700 setup on a single 6s pack!
Why not just adjust your headspeed to a lower setting vs. changing the batteries?
Less headspeed, less amp's drawn.
ESC's are most efficient at or as close to 100% as possible. Also if using governor mode it is still capable of producing huge current burst during hard manoeuvres due to the huge amount of overhead head speed available. You will burn your ESC up very quickly doing this!
Also as I mentioned before lowering the pack voltage means you can carry more capacity for the same weight or the same capacity with less weight.
If you are after bigger packs because you want more flight time, consider using 10s instead of 12s and 6-8000mah packs, this will give you MUCH more flight time at only a slight reduction in head speed (1900 instead of 2100 for example).
The motors Kv number is the motors rpm per volt so you can easily work out the motors max rpm by multiplying the Kv by the pack voltage say 12s 44.4v.
Then you just need to know your main and pinion tooth count and divide the main gear teeth by the pinion teeth. I think your 700 is 112T main and 12T pinion so you have 9.333, this is your gear ratio.Now all you do is divide the max motor rpm by the gear ratio e.g.:530kv x 44.4v = 23532 max motor rpm112 / 12 = 9.33323532 / 9.333 = 2521 max head speed.Obviously you would only hit this head speed with a fresh battery at 100% throttle which is why you would govern the head speed back to around 2000-2100 or use a lower throttle curve.
You will not damage anything using lower voltage packs. The only way you would damage the electronics is by using HIGHER voltage packs like if you tried to use 14s in a 12s heli for example.
You would not get the 6s 8000 packs in an 800 let alone a 600!You will not be running lighter packs because you will use bigger capacity packs. You will run 2 5s packs instead of 2 6s packs but each cell will be bigger in capacity. So for example a 6s 5000mah pack will weigh roughly the same as a 5s 6000mah pack. I use 5s 8000 in my 800 because that heli was meant for 6s 6000mah packs and they weigh roughly the same. So basically you are lowering the voltage but increasing the capacity to keep the pack weight roughly the same.
If you are using the Castle creations ESC's you just need to tell it you are running on 8 or 10s instead of 12 and reduce the head speeds to somewhere where it will govern properly. If you are not using the governor and just using throttle curves in your TX you will want to increase them by 10-20% or simple run a straight 100% throttle in idle up.
