Polyquest 30C vs lighter 18C high capacity

[tornet999]

wanted to discuss in general terms if it is better to select higher rated lipos than for example FP EVOlight in Hurricane. I use Z30A motor, but I guess the discussion is valid in general.

So for example Polyquest 2 x 3s 30C 3200 weight 550 gram vs 2x 4350 EVOlight above 600 gram.

I heard that the the Polyquests gives around 4.5 minutes of flight time (Z30), guess that is hard 3D. But the lighter lipos should give much longer flight time, but maybe with shortered life considering the rating.

I have ordered som Polyquest 30C, but maybe the high capacity track would have been better.
In other hand I always chaged my lipos at 2C on the field, guess a 30C lipos is better in handling that over time.

[ukgroucho]

You have two different parameters to consider here.. well three, but two directly affect performance and pack longevity.

C rating is important to a point but you have to balance this with pack capacity and heli requirements.
30C 3200s can hold (alegedly) better than 90 amps.. you're just not going to see this in a 550 Hurricane.
18C 4350s are in the 77amp sustained range.. again more than a Hurricane 550 needs.

Both of these packs should be fairly unstressed in a 550 - assuming manufacturer specs can be believed.

But WEIGHT is another factor - and the overall impact on the loading of the rotor disk. I'm still trying to get my own understanding of how this actually behaves in reality 'sorted'. Here are some current thoughts, maybe BS but I welcome some correction / adjustment.

Adding weight increases disk loading... 'reduces' the 'pop' when you pump cyclic. This is most noticeable in 3D manouvers - so with a heavier a pack / heli you will need to push cyclic 'harder' to get the desired result - which means bigger amp peaks. Overall power consumption will be higher with a heavier heli and my feeling is that this is not 'linear; across different flying styles.

For hover and FFF there will be an increase in overall power needs with more weight but it will not be huge and it is likely that the bigger pack will deliver longer flight time.

For more agressive flying this may not hold true... if the extra weight pushes the disk loading too high then the pilot will push the pack and motor VERY hard to try to get the heli to perform 3Dzz and overall power consumption will be much higher - so flight time may be little or no better than with a lighter setup.

In this later case I suspect that a blade change to slightly bigger blades with a small drop in HS might be the right answer - make it fly like a bigger (heavier) heli. I'm going to experiment with my 10S 550... it's somewhat heavy and I suspect disk loading is on the high side. I still get reasonable flight times with ballistic performance but I suspect that there is more that can be extracted from this rig. Running 500 CFs right now and looking at 530s to see what looks viable.

[Pinecone]

Remember, you are talking about 50 grams or so on a 2200 gram heli. SMALL wieght increase.

The same on a Trex would be noticeable. On and EP-100 deadly. :)