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Low Head Speed Helicopters Low Head Speed Helicopter Setups and Flying info


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Old 10-16-2017, 01:43 PM   #21 (permalink)
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I think I pretty much get it then.

I just swapped my 23 pinion for 20 on my L480 stretch. (212 main gear) Based on the online calcs I should be good for slightly above 2100 at 20% battery so my normal HS of 1900 should have a bit more to work with and my weaker batteries may not complain as much. Going to reset my ratios and see how it goes.

Calcs drop it roughly 200 rpm in the same 20% so that should equate to near 10% better power or efficiency or both.
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Old 10-16-2017, 07:57 PM   #22 (permalink)
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excellent results.
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Old 11-09-2017, 09:24 PM   #23 (permalink)
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"my weaker batteries may not complain as much"
Flew it with my worn battery and it flew great. More Correct gearing helped a bunch.

After recalc on my 550sx stretched to run 600 I dropped that pinion from 15 down to 13, reset my gear ratio in the vbar gov and gave it a quick spin at the same 1800 head speeds. It definitely had more pull with less bog. Same flight time or maybe better.

Thanks for steering me in the right direction Gary.
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Old 11-12-2017, 04:34 PM   #24 (permalink)
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Gearing down my stretched 480 totally let's me use my smaller old packs again without them complaining. Total win. Has such great power. I am so excited about the transformation and how it flies.
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Old 12-03-2017, 10:07 PM   #25 (permalink)
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Quote:
Originally Posted by gwright View Post
Smitty, 520kv, at 8.83 gearing, and 10s (37 volts), computes to 2178 mathematically available. Say you could go down to a 10 tooth pinion, that gets it down to 1815 according to the math. Still not very good for your 1500~1600 target, but a ton better than the current config. 400kv computes to 1675 using your current pinion of 12 tooth, and 10s batteries. I'd shoot for that. This should be the perfect motor for you, using your pinion and batteries, and setup for 1600~1650 max governed rpm. this is the same motor I'm using in my 700, but wound as a 16L, for 350kv. I was using this exact motor before, but was overgeared for my preferred style of flying, so i was only getting 12 to 14 minute flights. since you're using 10s and not 12s, the math works out very good for your desired rpms.

https://www.hacker-motor-shop.com/Br...5726735&p=5399

You have me thinking of a 350 kv and same pinion at 1495, up one tooth pinion for 10s and run 1500- 1550 head speeds and if I want to run 1695 I can go 12s.
I see there is an xnova in that kv, but not sure where to get one.

Is it splitting hairs from 400 to 350 as far as efficiency and 'power' (collective grunt ). Would I expect the 350 to be cooler and use less to yield longer flight times? From what I understand your biggest fuel gains (flight time) come from the lower head speeds, I've already experienced first hand the performance gains from more pitch and lower gearing.
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Old 12-05-2017, 12:43 AM   #26 (permalink)
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Quote:
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I would agree if you were doing some sort of energy calculation, but it's not, it's a calc for rpms, which are determined by kv and voltage, not efficiency
The Kv rating of the motor is the back EMF voltage it produces at a certain speed, and the only thing it has to do with rpm is that the supply voltage can't exceed the back EMF voltage. So it is a speed limiting factor for PM three-phase motors. It has nothing to do with how fast the motor will run at throttled frequency or PWM.

My 626 UAV heli uses 12S power with a 530Kv motor and 9.91 gears.

https://photos.app.goo.gl/Ujls42hHlgmCLDky1

So the Kv rating says the head is going to turn 2,100 rpm? It will at full throttle. But I set the governor to 1,550 rpm and it's perfectly happy at that speed and flies for 38 minutes with 4 minutes reserve in cruise flight. Put over 70 hours on it this past summer flying surveys with it. It is 14.8lbs takeoff weight and pulls 670 watts @ 31 mph cruise speed. The ESC doesn't overheat, the motor doesn't overheat. It's perfectly happy running on only 14-15 amps on 12S power.

When I first set the heli up for UAV use I tried running it on 8S power @ 1,500 rpm. Got about 9% more flight time out of it running it on 12S with the governor set at 1,550, with the same drivetrain. Both the ESC and motor actually run cooler on 12S because the motor is only pulling 14-15 amps vs 24-25 amps on 8S.
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Old 12-08-2017, 08:11 AM   #27 (permalink)
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Agree with everything Chris says, but his usage is quite different from a 3d setup, even a smooth, low headspeed 3d setup. He'll never see the high current spikes with aggressive collective. I'm guessing in his mode he could probably run the throttle wherever he wants it and not get anything hot. it's like when I hover an entire battery, my flight times go from 15 minutes or so of smooth 3d, give or take a couple minutes,.. up to a bit over 30 minutes. Everything is also at ambient temp .

in his last comments, he's seeing lower current with higher voltage and it appears not changing motor, gear, etc. however, it's steady state usage, and if that was flown aggressive 3d the current spikes would probably be extremely high.
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Old 12-08-2017, 09:06 AM   #28 (permalink)
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Quote:
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it's like when I hover an entire battery, my flight times go from 15 minutes or so of smooth 3d, give or take a couple minutes,.. up to a bit over 30 minutes.
Helicopters are least efficient in hover. When they start moving they go into translational lift where both the main rotor and tail rotor become more efficient. My 626 UAV pulls 840-850 watts in hover. 670-680 watts @ 30-35 mph cruise. 31 mph is best cruise speed for it on survey flights - has about 19 miles range in average wind. There is no multi-rotor that can match it for cruise speed, range and payload capacity on the same power.

If I toss it around and fly even mild sport aerobatics with it (It's kinda heavy for 3D) then the flight time goes down accordingly.
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Old 12-13-2017, 06:02 PM   #29 (permalink)
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OK I caved and ordered the hacker @400kv. Will see how it goes.
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Old 12-16-2017, 11:04 AM   #30 (permalink)
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Default Calculating pinions....

Dang it Gary - you got me thinking more about optimizing.

Sorry slightly off topic, but going for the formula.....

After seeing dramatic improvements from gearing and such I went from 23 to 20 on my 480 running 523's have my head speed set at 1900 ui1 pretty much all the time since it flies so amazing no need to change.
I get pretty much 9 minutes.
I have my IU2 at 2000.

So based on your formula 22.2x1070~10.6 = 2240
If I would gear it down 2 more on the pinion I would calculate it as
22.2x1070~11.77 = 2018

Am I thinking right?
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Old 12-21-2017, 07:44 AM   #31 (permalink)
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400 kv Hacker installed flown 2 packs.
So far so good. Not sure what the rpms are yet.
Over 10 minutes with the 4400 10s pack. Pulling big up lines big air and such. Lots of tic-tocs. Super windy. Typically that style of flying is when I've had esc's shut down. Esc not even warm, motor 85 degrees
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Old 12-22-2017, 12:28 PM   #32 (permalink)
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Quote:
Originally Posted by smittylube View Post
400 kv Hacker installed flown 2 packs.
So far so good. Not sure what the rpms are yet.
Over 10 minutes with the 4400 10s pack. Pulling big up lines big air and such. Lots of tic-tocs. Super windy. Typically that style of flying is when I've had esc's shut down. Esc not even warm, motor 85 degrees

Awesome sounds like it is working very well.
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Old 12-23-2017, 10:42 AM   #33 (permalink)
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Cold weather here, flew one pack yesterday. Roughly 8 minutes 2200 mah.
Motor 85 esc 65 ambient 55. My old tired Batteries don't work well at these temps. They barely warm up.
Tack coming hopefully next week for some better info.

Tail has a little kick when the esc governs. Sometimes if I come down on a loop and overspeed the set rpms it kicks as it settles. Not sure what will solve that. Tail holds full speed tail slides- so I must have enough head speed overall.
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Old 01-01-2018, 11:56 AM   #34 (permalink)
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Ongoing update.

Installed a telemetry tach and found it won't get past 1600 rpm with the 10s.

Flying weight is just over 8.5 lbs.

I get some random head oscillations at different speeds near 1575, but it may go away next pack at the same speeds.

Ordered a 13 pinion to allow up to 1700 calculated. Also ordered some medium dampers and am going to try the VTX as they may like the lower head speeds. (Rails fly really good, but might as well try them.)

At 1550 I can get 10 minute + flights with 4000/4400 packs.
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Old 01-05-2018, 07:48 PM   #35 (permalink)
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13 tooth pinion installed and hovered. 80% throttle is perfect 1600.

Set the 3 curves to 1500/1550/1600
Flight testing to resume hopefully this weekend.

All this testing lets you figure out what head speeds you (I) like to fly.
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Old 01-06-2018, 09:38 PM   #36 (permalink)
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Default What I've learned through this process.

Took it out for a spin today.

For me I found I much prefer 1600 with the tail gearing stock still.
13 pinion compared to 12 on paper gives me 1700 tops, but reality with my jive esc in. Mode 4 gov I can get 1625 at 80% throttle curve. ( max suggested in the esc manual) I would expect another esc or vbar gov setup to work better as this kicks as it governs. Tail will hold ok at say 1500, but I may not trust it totally much lower.

What I've found playing with pinions and motors is if you gear it down enough that it doesn't go to your highest set target rpm then you are near the end of the pack you are about one tooth too small and you've eliminated the overhead. Adding a tooth gets it back.

Also I found this worked on my other ones as well.- my 550 I stretched to run 600 blades flies really nice at 1800 and when geared as low as possible doesn't heat up the battery and roughly 9 minutes.
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Old 01-07-2018, 11:05 AM   #37 (permalink)
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I plan on using the Hacker 400 KV Motor, 12S, 11 Tooth Pinion, Tri Blade Tail, Scorpion Tribunus 200 amp ESC, VBar Neo, Neo Governor, Gearing is 1580 rpm. But I want to run around 1250 rpm, 1350 rpm, 1550 rpm. I was flying my Logo 600SE down to 1100 to 1150 rpm. But I want to add the tri tail.
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Old 01-07-2018, 09:32 PM   #38 (permalink)
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I would suggest that as well.
My esc seems to give a tail kick when it hits the governed or set head speeds. So a different esc that can use the vbar gov should be perfect. My other two logos with the YGE esc don't do the kick like the jive does.

I also find the tail seems to hold on long down lines say tail slide or sideways, but you just can't argue with a tail that holds. Yes tri tail should be a great option.

This motor should work exactly perfect for you in your setup. As well the lower HS will net you flight time.

The only other thing I could add is if you don't have the esc yet you may reconsider as I found the peak amps far less than you would expect. I just am not sure what one would be the best option. I suspect your choice would be a great one.
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Old 01-08-2018, 10:26 AM   #39 (permalink)
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Another observation I found was flying the VTX at the lower head speeds flies excellent, however since my setup is so light and the VTX blades are 5 or 6 grams heavier than the rails it really gets into a wobble at certain speeds, but also IMO VTX don't carry as much momentum as the rails for autos.

And lastly with the proper gearing for what your targeting at the end of the pack I flip to my highest set head speed and if it still will spool up to that your good, where the lower gearing wont allow it.
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Old 01-09-2018, 07:20 PM   #40 (permalink)
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I have the Scorpion Tribunus 14-200 ESc on there already. So I will just keep it.

I am going to build a Synergy E5SS and I have a Scorpion Tribunus 12-130 ESc on the way.

I have Rail and VTX 697mm blades.
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