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HomeAircraftHelicopterLow Head Speed Helicopters › Is It Worth It?
02-25-2018 06:41 PM  3 months agoPost 1
mcfast

rrKey Veteran

Quebec Quebec Canada

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I just finish building a low head speed helli, 700 size, to get the CG where I like it I use a 6s 8000ma battery the helli it is a bit heavy, but it flys great I was thinking of modifying it to an 800 size to reduce the disk loading, do you guys think I could get longer flight times.
And by the way this about the lowest budget LHS FBL helli you can build but all new, this what I got an Assault 700 $228.06 Gart motor 530KV 4200 watts $85.00 K-BAR Pro FBL unit 46.00 the cyclic servos $31.18 X 3 tail servo $31.57 ESC $48.82 battery 8000mAh 6S $47.00 free shipping and about $30.00 odds and ends and about $60.00 for shipping for all the parts and hell, so far she flys great! we will see how long it will last, I do not fly that much and no 3D, so far so good, I just finish it and it is winter here did not fly much as of now, but this summer we will do a lot more!

P.S. sorry for the spelling or the grammar I am dyslexic!

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02-25-2018 07:25 PM  3 months agoPost 2
ICUR1-2

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Ottawa, Ontario

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Just speculating here.
If you make the blades larger it will require more energy to fly the same HS.They are heavier and create more lift. So unless you reduce your HS I believe your times will shorten. At best you'll have the same flight times at a Lower HS with the same lift.

On my 600N I get better flight times with 570's compared to 600's
It flies heavier but I can punch it without overly worrying about the head.

spending time, paying attention

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02-25-2018 07:28 PM  3 months agoPost 3
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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Someone must know of a chart for rotor diameter to weight

spending time, paying attention

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02-25-2018 07:38 PM  3 months agoPost 4
turboomni

rrProfessor

East of the Equator

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If you were to try that I would ether get a lower kv motor and or a smaller pinion to zero in on your target head speed. On my LHS 700 I run a Talon 90 esc with the smallest pinion I could find which turns into 1300 to 1350 headspeed with a 6 cell for an easy 10 minute run. I run the motor/esc 100% throttle to keep efficiencey high as the Talon doesn't have free wheeling.
If your esc does not have this either lowering the throttle too much will be more inefficient and heat up. Ask the guru of this ,,Mr Wright he knows far more than I. I do hope you like LHS heli's as much as I.
Good luck!

Setup is everything, All my heli's can fly far better than I can pilot them

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02-26-2018 12:51 AM  3 months agoPost 5
mcfast

rrKey Veteran

Quebec Quebec Canada

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I do have smaller pinions, right now my head speed is around 1200 at 100%, throttle. if I go with the 800 blades I could go down to around, 900 HS, which is about right for an 800 but is it worth it, I can modify the 700 to an 800 for around a $100 with the blades, that is cheap! I think I will try a see.

P.S. sorry for the spelling or the grammar I am dyslexic!

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02-26-2018 12:58 AM  3 months agoPost 6
turboomni

rrProfessor

East of the Equator

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Cool Beans!! Looking forward to your report. I wonder if you are going to lose tail authority with the bigger disc and the lower head and tail speed. I guess if you like it but the tail is vague you could get bigger tail blades or change the ratio and a last resort a 3 bladed tail assembly. Can you tell us your setup now? Motor kv pinion tail ratio etc and what your are going to? Thanks.

Setup is everything, All my heli's can fly far better than I can pilot them

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02-26-2018 10:00 PM  3 months agoPost 7
mcfast

rrKey Veteran

Quebec Quebec Canada

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Right now I got a 530KV motor with a 14 tooth pinion and a 120 tooth main gear, the tail spins just a bit over 4 turns to 1 turn of the main blades.

P.S. sorry for the spelling or the grammar I am dyslexic!

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02-27-2018 01:42 AM  3 months agoPost 8
JuanRodriguez

rrProfessor

The Villages, Florida

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mcfast
And by the way this about the lowest budget LHS FBL helli you can build
Maybe you can update your topic or first post to reflect that ???

Been there, done that and old enough to know better.....

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02-27-2018 01:57 PM  3 months agoPost 9
gwright

rrVeteran

Champaign Il

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ICUR1-2
Someone must know of a chart for rotor diameter to weight
What's the goal?,.. just overall disk loading?That's actually pretty easy to put into a spreadsheet.

My basic rule of thumb is always bigger disk and lower weight

As for the main topic here, 12S and very low KV motor is what I prefer. Higher voltage and lower current, very efficient and everything stays cool. my 516 and 600 fly on 6S, but I didn't have low enough kv motors, so they get a bit warmer and only go 7 to 10 minutes. my 700's and 800's have always been 12S. Currently a 350kv motor in the 700 with 12s/4350 for flights of around 15 minutes at 1200, give or take a couple minutes depending on flight style for a particular flight. It's only 9.75 lbs flying weight(yes, with batteries). The bigger issue I've seen is tail ratio. the tails kinda work on the really light 6s setups because they're flying at lower power levels and in some cases even lower weight, so lower angle of attack on the blades and less torque to deal with. i generally have to speed them up. My 600 and 700 are at 5.45 to one and the 516 is at 6 to 1. Still can't go too low on headspeed or tails don't always hold with the way I fly. 516 is at 1700 and occasionally 2100 but only 80.6mm tails. Need to go up to 96's so i can slow it down more. The 600 is at 1500 and occassionally 1900, with 105mm tails. and the 700 is at 1200 and occasionally 1450 with 116 tails. If I go lower than those lows I can have issues with the tail holding in fast sideways or pirouetting aerobatics.

Gary Wright

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04-16-2018 02:27 PM  63 days agoPost 10
Richardmid1

rrProfessor

Leeds, England

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You could go to 5s 8000mah and keep the same pinion and even throttle curve and get longer flights due to the lower weight (roughly 200g) and lower head speed.

Also your head speed will be 1300-1400 with the 6s setup at 100% throttle not 1200. Head speed if you switched to 5s and kept everything else the same would be around 1150 but you could govern to 900-1000 no problem.

60% of the time, it works every time!

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