Longest flight time possible with an electric FPV heli?

[Hizlimax]

I'm planning to build an electric heli with just FPV stuff like a small FPV camera, eagle tree OSD, 5.8 VTX and maybe a GoPro when I want to shoot in HD. I'm very happy with my Naza-M so I'm planning to use the new Naza-H for this build. My main goal is to maximize flight time and fly FPV within my 2.4 TX range. I'm all in for suggestions like using longer tail booms, longer asymmetrical main blades, lower headspeeds with matching pinions, handwounding motors, choosing lower C rating batteries because of less weight and all other tips you guys might have. To put it simply how far can flight time be stretched for an FPV heli? Price and heli size are not the main factors in this build and I'm assuming it has to be bigger than 500 to have a tidy setup without using an extended landing gear. Could an Align kit be a good choice for such build? I'm not sure how they compare to other brands in terms of weight. Thanks for all your input.

[satgod]

a electric helli from start to finish average flight time is about 8 minutes with no acro

for long fpv a plane is the only way to go
even on a quad with a big pack 10-15 minutes safely is it

[Wesley888]

I strap 2 packs of Lipo at the bottom of a 450 with GoPro2 and it can fly about 14-15 mins. I think 15 mins is about the longest you can get.

[Raven_poland]

Hi!

I did about 16min. 30 sec. flight on Trex 600 Pro, 12S 2x3300 mAh.
Original symmetrical blades, RPM was lowered to 1500 rev/min to get max time. Heli was perfectly controllable. Of course NO acro at all. Gentle forward flight - circles, eights as to avoid hovering which would reduce the time.
I am planning to put FPV equipment onboard and the flight time is essential for me.
I will order assymetrical blades soon. Would you think that I should go for a bit bigger blades - 620mm? or stay with 600? regarding the flight time of course! I am aiming to exceed 20 minutes!

Greetings from Poland

[Hizlimax]

Hi Raven,

I was also aiming for a flight time around 20mins. Could you share the battery voltage you had after you landed? I believe the lowest possible headspeed along with the longest blades you can fit will gain you the most flight time at first. You could even stretch the tail boom and use even longer mains. I have Spin Blades 435mm assymmetrical main blades for my Trex 500 and they do provide better lift and the build quality is great. They are much wider than the Align blades as well. Check out this thread which talks about 27 minute flight time with a Trex 700:

https://www.helifreak.com/showthread.php?t=301397

Cheers from Turkey

[windsnob]

I put 2 6s packs (total 9300 mAh) on my Gaui X5 fully decked out with FPV gear with 515mm asymetrical spinblades running at 1800rpm and got a 20 minute flight. Used up 80% of the packs. It flew pretty decent at 1800 ... I'm sure I can go lower to gain even more time.

[Raven_poland]

Originally Posted by Hizlimax

Hi Raven,

I was also aiming for a flight time around 20mins. Could you share the battery voltage you had after you landed? I believe the lowest possible headspeed along with the longest blades you can fit will gain you the most flight time at first. You could even stretch the tail boom and use even longer mains. I have Spin Blades 435mm assymmetrical main blades for my Trex 500 and they do provide better lift and the build quality is great. They are much wider than the Align blades as well. Check out this thread which talks about 27 minute flight time with a Trex 700:

https://www.helifreak.com/showthread.php?t=301397

Cheers from Turkey

I have two lipomonitors connected to both main batteries set at 3,7v/cell
I land when they start beeping. After eng. shutdown the voltage is about 3,8-3,85v/cell.
I hope I don't drain the batt too much!

[KSHeli]

Kansas State University at Salina has a aviation department and they have an FPV that I think may have up to 6- 5000 mah 6s batteries on board outside the frame to get longer flight times don't know what their fight times are but you need to also look asymmetrical blades also. Since the flights aren't aggressive and you look at lower headspeeds flight times will increase.
I don't know what their flight times are but its set up for competitions.


edit: If you are only going down to 3.85V you are not even getting to the storage voltage yet set it down even lower when you get done 3.3V is still not a problem. The 3.8V is a good value to get to while breaking in Lipo Batterie, but after a dozen or so flights you can start getting more aggressive with your flight times. Just don't go below 3.0V.

[Raven_poland]

Actually I was doing a break-in of the lipos as I did about 5 flight only after the final assembly of my 600PRO.
Some sources say that it's not good to go below 3,8v/cell as it degrades lipos much quicker.
I have read not to go over 80% of the capacity - which is in fact about 3,7 - 3,8v - I've checked after the flight the batteries take about 2700-2800mAh during charging (they are 3300mAh).
Next I will try assymetrical and a bit bigger - 620mm.
The winter has come to Poland - now we have -10 Celsius! (MINUS TEN!) so I think I will wait till spring with my next experiments

[KSHeli]

On my Trex 700 I'll fly down to 3.75 V and have to put back in maybe 2800mah. Well at least your keep an eye on the charging characteristics of your batteries.

[Hizlimax]

Originally Posted by Raven_poland

I have two lipomonitors connected to both main batteries set at 3,7v/cell
I land when they start beeping. After eng. shutdown the voltage is about 3,8-3,85v/cell.
I hope I don't drain the batt too much!

You can set your lipomonitor alarm to 3.5v/cell as it will start beeping when it sees one of the cells below that which means you will still have some 3.55s or even 3.60s on other cells. When you land you will still see 3.7s which is still in the safe zone imo.