tIANci,

Hello there my old friend. I hope you've been doing well. We need to catch up on some PMs.

Your not so great experience with 6S is documented by you on page 7 and 8 of this thread.
Just remember that was not a good combination nor was it a good motor as per your comments,..... so not all 6S setups are bad.

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pani,

Forget the advertised AMP rating of your motor. People run that motor on 65AMP to low 70A range on regular basis with no issues. I would rather see it kept closer to 60-65A for daily use, but some guys are pushing it harder.

You are under propped. You can see HUGE gains in power and speed with use of larger diameter prop and/or increase in voltage.

I know 5S would be awesome setup for your motor in Funjet if you can keep up the amps for Jaw dropping climbing and speed.

6S given your KV becomes a little questionable, although my simulation says that if you can swing 5X5 on low 70A range that it would go faster than a 5S setup. Still I rather see a 5S 2500-2700 pack at 30C.

It is not all about more power, if prop size is not there you might not have enough thrust to overcome the drag in order to go faster although you may have plenty of prop pitch speed.

Being thrust limited does not come into play till at higher speeds, but for sure a small diameter prop (on a given pack) will have reduced acceleration, harder launch and reduced climbing (as compared to a larger diameter prop)....you must have felt its reduced acceleration when you went to 5.2X5.2
I suspect that it could fly a little faster with 5.2" prop but you need a longer run to get up to speed.

On 4S motor can handle 6X5.5 easily, so question becomes your ESC, and batteries and how far you are willing to push them....besides the Funjet's ability to provide cooling air to motor.
A few full throttle runs and some throttle management would be fine when combined with a heat sink. Medusa makes the best heat sinks for 28mm motors and is available in 2 lengths.

No question you can fly at 140 MPH with your motor on that plane...Question is how much faster.
Do you have better batteries and ESC?
Were you going to buy 6S or run (2) of your identical 3S packs which are in same exact condition. If you were going to buy new pack(s), then consider 5S good enough for 70A even if you'll run a little less Amps.

Usually I hear weight complaints when a person's power to weight ratio was poor, at times due to a huge huge huge pack for only 800W or when a person is used to flying a Funjet slow and does acrobatics at low speeds or land at real slow speeds…when those guys increase Funjet weight, they are disappointed.

High speed:
It is a compromise and also people get used to anything in 2 weeks. Then they wonder why they didn't do that combination sooner for that new realm of high speed fun, the grin will not leave your face. Make sure the rest of your plane can keep up with quality servos/rods/clevises and any strengthening mods needed, your skills and being able to handle greater financial losses in case of a mishap.
The 72 MHZ receiver needs to be placed far from ESC and motor and UBEC. If 2.4 GHZ, then stay away from AR6100 and AR6300 in favor of AR6200 and AR7000, possibly the new AR500.

Right now, your awesome motor is bored in tears at those medium amps.

Want to chat with others who fly same motor at high amps, then send me a PM for some contact info.


Gryphon