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HelicopterLow Head Speed Helicopters › Low head speed question
08-20-2014 06:00 PM  3 years agoPost 1
Busher

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Manchester, England

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Have I got this right?

To achieve the low headspeed on your 700 size helis, all you have done is take a standard 12s heli setup, say a trex 700e, kept everything bone stock, but removed one battery to make it a 12s setup with only a 6s battery for power?

If that's the case I'm seriously thinking of buying a 700 for playing with, but I'm wondering if I'm missing something ?

I mean if it doesn't work I can always put the second battery on and I'm back to normal

Good luck
Busher

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08-20-2014 08:40 PM  3 years agoPost 2
wrongler

rrProfessor

Brewerton, New York

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I did that with a 12S TDR. Made a Jumper for the missing lipo and flew on 6S. No issues!

Bill Whittaker

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08-20-2014 10:54 PM  3 years agoPost 3
Retired2011

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Lee's Summit, MO

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Have I got this right?
Yep!

Very likely will want to bump your tail gain up a little, or increase tail blade size if your head speed is too low.

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08-20-2014 11:45 PM  3 years agoPost 4
turboomni

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East of the Equator

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What would happen if instead of a 12 cell esc you used a 6 cell esc in the 700? Would efficiency go down?
My gut reaction would be it would be less efficient. My thought was using the lightest esc instead of the bigger esc to save some weight if it was not needed.

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

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08-21-2014 01:25 AM  3 years agoPost 5
Retired2011

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Lee's Summit, MO

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I don't think you'll see a weight savings there...
in fact a Castle HV is less weight than a comparable Castle LV.

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08-22-2014 12:45 AM  3 years agoPost 6
turboomni

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East of the Equator

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so what about efficiency?

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

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08-22-2014 01:43 AM  3 years agoPost 7
Retired2011

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Lee's Summit, MO

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so what about efficiency?
You're over my head there, we'll have to wait for somebody smart to answer that.
I think the most important factor is the head speed, meanigng less resistance to spinning the blades, regardless of how you get there.

I just fly 'em, and don't worry much about the technical aspects.
If it doesn't crash, I figure everything is good.

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08-22-2014 01:52 AM  3 years agoPost 8
turboomni

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East of the Equator

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Lol! I am just gathering information for my future project for this winter. I want to build a ground up 700 low headspeed only heli. Built as lightly as possible. Target range 1000 to 1600 head speed. I havent decided yet to go 6 or small 12 cell cause I don't know much about this!!! Maybe I'll start a topic here "What is your low head speed heli setup?" Maybe I'm making it more complicated than it is ,,,I don't know.

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

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08-22-2014 02:26 AM  3 years agoPost 9
Santiago P

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South West, Ohio

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Have I got this right?

To achieve the low headspeed on your 700 size helis, all you have done is take a standard 12s heli setup, say a trex 700e, kept everything bone stock, but removed one battery to make it a 12s setup with only a 6s battery for power?
Yep

If you run a Kontronik ESC is a plug and play deal. But if you run a Castle you must run the castle link software and program the new voltage parameters.

Either way is lots of fun pushing the limits at low head RPMs.

You need at least a 2K RPM setup @ 12S to run correctly @ 6S

Santiago

Team Minicopter - PeakAircraft.com
bavarianDEMON- Team Kontronik - Scorpion Motors-

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08-22-2014 04:48 AM  3 years agoPost 10
theriddick45

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United States

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To add up to the plate you can run a CC with Vbar using the Vbar gov. That's what I'm doing. So far I have decided to use my 800 strictly 6s so I put it on a diet. So far the weight is 9.4 ready to fly. Battery is a gens 5300 CC 80hv. But I can only get about 10 to maybe 12 minutes @ 1200hs I'm looking to increase the flight time to 15min. Like Timo wendland in this video.

Watch at YouTube

Suzi Janis 800e & 700e 3blade both w/Ikon

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08-22-2014 04:52 AM  3 years agoPost 11
theriddick45

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United States

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I'm using the align 750mx 530kv, Savox servos, no bec, spin blades Matt black, is a Suzy Janis conversion kit.

Suzi Janis 800e & 700e 3blade both w/Ikon

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08-22-2014 09:07 AM  3 years agoPost 12
Busher

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Manchester, England

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Thanks for the info it will get me a good start
Has anybody got any 6s current data that will help me out with speed control choices, I know the kontroniks have active freewheeling, so could you also use say yep/ yge type esc,s as they also have active freewheeling? I never thought of using the FBL gov either.

My thoughts are to go with a 12s speed control but if I can get away with 6s one they are a more reasonable choice

Good luck
Busher

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08-22-2014 11:32 AM  3 years agoPost 13
Retired2011

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Lee's Summit, MO

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Yes as far I as I know all of the ESC's you mentioned have AFW.

However, I also fly my Synergy with a CC Edge 120 HV on 6s with no changes needed, using the V Bar gov.

I'll check the CC log from the last 6s flight to see if I can give you some data...won't be today though.

I love that Timo vid, it's one of my all time favorites...
what a beautiful place to fly!

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08-22-2014 03:30 PM  3 years agoPost 14
gwright

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Champaign Il

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Love Timo's vids. I hope to fly that smoothly some day.

For 6S only, the requirements are quite different, so you may want to try the talon 90. The BEC included is very good, so no rx pack or seperate BEC needed. It's a couple ounces lighter than the 120 EDGE HV that's commonly used. Add the weight savings of the ESC, plus no rx pack or seperate BEC and you end up with a substantial weight loss. On 6S, you'll see 20~25ish amps average and probably no higher than 50 to 60 amp peaks so it would be just fine with plenty of reserve. On my low rpm 12S setups I see lower currents than that. On my 800 machine I see 8~9 amps in hover and peaks never over 30 amps, when doing smooth 3D at 1100. Figure on slightly less than double those numbers with the 6S setup. The same energy would mean double but the machine will be 15~20% lighter so you probably won't hit double the amps (60) for peaks

Gary Wright

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08-22-2014 03:48 PM  3 years agoPost 15
unclejane

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santa fe, NM, USA

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You're over my head there, we'll have to wait for somebody smart to answer that.
I think the most important factor is the head speed, meanigng less resistance to spinning the blades, regardless of how you get there.
I just fly 'em, and don't worry much about the technical aspects.
If it doesn't crash, I figure everything is good.
That's been my approach also. My application is poor-man's-full-scale, FPV-only. So if it gets off the ground and doesn't drift, that's good enough for me. If there are inefficiencies in the system I practically don't care because I want to take a break after about 10 minutes of flying anyway.

For example, pulling a pack on my trex 800 is definitely sub-optimal, since the pack (5200mah 6S) goes past 50% depleted at about 9 minutes. The motor (align 850MX, 490KV) comes down almost hot at the end of the flight, so there's definitely some wasted energy there. My old-school trex 700, OTOH, has a 700MX 470kv in it that barely gets warm - I have the timer set at 13 minutes with the same batt to get to below 50%.

So basically you can do it by simply pulling a pack on a 700/800 size, but there's no guarantee that it'll be a really optimized LHS setup. OTOH, it takes time and money to really do it right, neither of which I have in any abundance lol. But since it doesn't cost anything to do this, it's worth a try to see if it works in your application. I was lucky that it's spot on for what I want to do and the inefficiencies I'm perfectly able to live with....

LS

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08-23-2014 04:21 AM  3 years agoPost 16
turboomni

rrProfessor

East of the Equator

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For 6S only, the requirements are quite different, so you may want to try the talon 90. The BEC included is very good, so no rx pack or seperate BEC needed. It's a couple ounces lighter than the 120 EDGE HV that's commonly used. Add the weight savings of the ESC, plus no rx pack or seperate BEC and you end up with a substantial weight loss. On 6S, you'll see 20~25ish amps average and probably no higher than 50 to 60 amp peaks so it would be just fine with plenty of reserve. On my low rpm 12S setups I see lower currents than that. On my 800 machine I see 8~9 amps in hover and peaks never over 30 amps, when doing smooth 3D at 1100. Figure on slightly less than double those numbers with the 6S setup. The same energy would mean double but the machine will be 15~20% lighter so you probably won't hit double the amps (60) for peaks
Thanks for that info Gary. I was wondering if the Talon 90 would be a good choice as I was thinking of using that esc. The weight savings with a FBLs unit with satellites would be a good weight savings. Now I would ask in a low head speed heli what are the servo torque requirements and speed requirements for such a beast? Do you need less torque and speed? Or more torque and speed? I would think this would be another minor area for weight savings depending on the servo needed. Also head design,,I am shying away from a dfc head going to an older type flybarless head for less rigid dampening,,,is this correct? By the way ,,nice article in the newest edition of Model Aviation Magazine!!!! You know your stuff!!

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

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08-23-2014 12:00 PM  3 years agoPost 17
gwright

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Champaign Il

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not sure about servo torque requirements. Should be less but the helis are setup for specific size servos so I haven't messed with going smaller. I still have a high rpm mode on my machines also, so it's not warranted anyway. As for head design, I have my own opinions on that, that differ from some others, and everything I fly has a dampened head that can teeter. I figure if it has damping and can teeter, no matter how stiff the damping, then it can snap before it gives and I don't like intentionally flying things that can be dangerous and prone to failure. It the head has no damping whatsoever like some of the multi blade stuff I've seen, than it may be OK. I'd like to try one of those sometime to see just how different it flies. Since you essentially speed up the control loop by 50% the fbl gyro just may work a lot better, but I hate to loose aerodynamic efficiency with the extra blade. I'd love to have my thinking proven wrong on that, as it may allow much lower revs.

Thanks for the comment on the article in MA. I love writing things like that ( I often get complaints about my war and peace style emails <G>.That was much shorter than intended, but I had a deadline, and procrastinated as usual, and had to write that on my laptop in the van riding from the motel to the Joe Nall event one morning. That was probably a good thing because it didn't go on for 10 pages <G>.

Gary Wright

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08-23-2014 12:19 PM  3 years agoPost 18
Retired2011

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Lee's Summit, MO

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I want to take a break after about 10 minutes of flying anyway.
Me too, I usually can't stand even 10 mins.

I fly low head speed for the relaxing style, not extended flight times, and I like to be able to put a 12s pack in and fly it whenever I'm in the mood.

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08-23-2014 02:34 PM  3 years agoPost 19
turboomni

rrProfessor

East of the Equator

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[quote]not sure about servo torque requirements. Should be less but the helis are setup for specific size servos so I haven't messed with going smaller. I still have a high rpm mode on my machines also, so it's not warranted anyway. As for head design, I have my own opinions on that, that differ from some others, and everything I fly has a dampened head that can teeter. I figure if it has damping and can teeter, no matter how stiff the damping, then it can snap before it gives and I don't like intentionally flying things that can be dangerous and prone to failure. It the head has no damping whatsoever like some of the multi blade stuff I've seen, than it may be OK. I'd like to try one of those sometime to see just how different it flies. Since you essentially speed up the control loop by 50% the fbl gyro just may work a lot better, but I hate to loose aerodynamic efficiency with the extra blade. I'd love to have my thinking proven wrong on that, as it may allow much lower revs.

I wasn't thinking of going to a smaller sized servo ,,just the requirements and different weights between model servos. A small point for sure. As far as dampeners no matter what the head,, does a low head speed helicopter use softer dampeners than a high head speed heli in general? Or is it just a try it and see scenario? A three blade head fascinates me also. JR has a 550 based electric heli with a 3 blade system. I have heard no reports on the model.

Hey Chet ,,I am a gasser heli pilot and have two gassers. I set my timer for 15 minutes and land with between 1/4 to 1/3 left in the tank!! The thing about low headspeed E heli's and my gassers is when you have alot of time on your timer ,,you are not in a rush to do anything. Need a break to think about what to practice next?? Hover for a minute ,,,,and think...no big deal and go try it. Thats why I like gassers and hopefully a LHS electric heli.

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

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08-23-2014 04:30 PM  3 years agoPost 20
gwright

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Champaign Il

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In general, yes, softer damping for lower headspeeds (damping not dampening, they're not wet <G>. With the gyros we have now for the swashplates, damping isn't always required. However, You can of course see some nodding if the fbl gyro isn't tuned just right for little or no damping. It was the same way with flybars, and we'd just softern things since we couldn't tune the flybar as well as you can the electronic units.

Gary Wright

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