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HelicopterMain Discussion › Longer flight time model and setup choices
08-18-2014 01:48 PM  3 years agoPost 21
Rudy

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Houston TX/Bend OR

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Ronald, that post tells us so much about you. I'm sure that Team Mikado is so proud of you.

Rudy Ackerman Houston TX/Bend OR

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08-18-2014 02:39 PM  3 years agoPost 22
Ronald Thomas

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Gainesville, Fl, USA

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Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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08-18-2014 02:49 PM  3 years agoPost 23
gwright

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Champaign Il

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Longer flight times
Very nice. Gary what was your set up, battery's etc.
Thanks
870Heli
Those are older videos and setups have changed, so not really relevant. My current setups have a good bit more performance. I also use telemetry now with an alarm for 4000mah used so i know when to land. currently using CGY750's, hacker Turnado's, the 400kv or 450kv depending on gearing available in each machine, 12S/5000, and edge 120HV ESC's. The 80HV's should actually be fine in any of them, as I rarely ever see 100 amps in the logs, usually 60 to 80 for the peaks. 16/16 collective and 11/11 cyclic. Collective is a bit less in the higher rpm modes. E700 modes are 1350/1550/1750, E720 modes are 1200/1600/1800, and E820 mode are 1100/1400/1600.

Most flights are 12 to 14 minutes with the occassional short one where I use high rpm mode a lot and only get 10 or so minutes. I flip back and forth into different rpms during flight to more efficiently use the energy for what I want to do at that moment. High speed aerobatics don't really work at 1100 on my 820 for instance, but spinning high rpm doing slow smooth stuff is an incredible waste of energy, so i flip back and forth. With telemetry and esc logs it's easy to see that at 1600 on my E820 (highest rpm on it) it uses a bit over three times the energy from the pack that it does at 1100 so my thought is why should I fly slower smooth stuff at an innefficient rpm and waste energy. At first I thought telemetry for capacity usage would just be a neat thing to have, but now I find it a necessity. With multiple rpms used, flight time to 4000mah can vary DRASTICALLY so with just using a timer, you risk running the packs down too far and hitting cuttoff (which I did many times in the past), or landing early and leaving half the pack unused. With telemetry it takes all the guess work out.

Gary Wright

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08-18-2014 03:47 PM  3 years agoPost 24
Ace Dude

rrProfessor

USA

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I also use telemetry now with an alarm for 4000mah used so i know when to land.
Hi Gary, Which telemetry sensor are you using for this?

  

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08-18-2014 03:56 PM  3 years agoPost 25
gwright

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Champaign Il

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unisense-e from sm modelbau

Gary Wright

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08-18-2014 04:16 PM  3 years agoPost 26
Ace Dude

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USA

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Thanks Gary.

  

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08-18-2014 04:22 PM  3 years agoPost 27
gwright

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Champaign Il

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beware, instructions, and the software to use with the dongle (yes, you must get one to set them up with) are all in german. took me hours and a few adult beverages to configure the first one,..now takes seconds. Well, that's an exaggeration,..probably a couple minutes <G>.

Gary Wright

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08-18-2014 04:43 PM  3 years agoPost 28
Ace Dude

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USA

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Thanks for the heads-up. I tried to use their website to order a UniLog 2 and UniDisplay a few months ago and if it wasn't for Google Translate there's no way I could have completed the order.

Maybe we can get the German Speed Cup guys to give us German lessons at IRCHA next year....

  

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08-18-2014 04:57 PM  3 years agoPost 29
gwright

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Champaign Il

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Unfortunately, we are american.

person that speaks three languages: Trilingual

person that speaks two languages: bilingual

person that speaks only one language: American

only a couple things you have to tweak with Dongle,.. first is to set it to FASSTEST (or whatever protocol your radio uses) since the default is something else,..I think it's the graupner protocol. Next, set gear ratio for your heli, and finally change the setting that makes it zero out capacity versus add on and make it cumulative every time you plug in. Save and exit.

for your transmitter: Register the sensor with your transmitter,...three times (it's really three sensors in one little package). Link reciever correctly for bi-directional fasstest and in the correct rx mode (link using transmitter rather than pushing the button on the rx,.. only avail on 14SG and 18MZ by the way). At that point you setup your telemetry display screen for the information you want to see , and set any alarm thresholds you want.
Fly and have fun.

Gary Wright

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08-19-2014 02:30 PM  3 years agoPost 30
HeliNutAndy

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worcester, MA USA

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Before I go out and get another kit I'd like to experiment a bit with my Goblin 500. Here is my current setup:

18 tooth pinion
QUANTUM Outrunner Brushless Heli Motor (4120- 1200KV)
Jive 80 HV Governed at %80
165 main gear

According to Mel's head speed calculator this gives me a head speed of ~2750 which seems a bit high to me. I have a few questions.

1) How can I know what I can use for a pinion with out stressing my motor or esc? I would like to try some smaller pinions to bring my head speed down.

2) What would be a good slow head speed for the 500 or do I have to keep experimenting?

3) Is the Goblin too heavy for this? Pls no SAB bashing, I realize everyone has their favorite models...

Any help would greatly be appreciated. I do not want to purchase a bunch of pinions if they will not work.

Thx again,
Andy

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08-19-2014 03:22 PM  3 years agoPost 31
gwright

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Champaign Il

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I don’t like to use any of the “online headspeed calculators” due to their inclusion of an efficiency calculation. Efficiency really has nothing to do with calculating headspeeds. Take two motors of the same KV but one is far more efficient than the other. Apply the same voltage. They’ll turn the same rpms. Same holds true under load in the heli. Voltage times KV times gearing, and you get a possible rpm. Doesn’t matter if one motor is more efficient than the other, the rpms will be the same. The power drawn from the battery will be vastly different, but the rpms will be the same. I use 3.7V per cell, and ,my goal is a motor with an appropriate KV and pinion to max out at the rpms I want to turn.. i.e. no overhead in the calculations. Voltage will be a bit above 3.7V so there will be some headroom. If not enough I’ve been known to increase timing in the controller a bit (20 degrees advanced in some instances), which raises the KV a little bit and gives me that small amount of headroom I need. Yes,.. the castle software, in set rpm mode ALWAYS yells at me that I don’t have enough headroom <G>. Strangely enough they always govern just fine in my high rpm modes, yet the governer is leaves a lot to be desired in the low rpm mode.

For your goblin, You’d need to do the math. I’m not sure what’s available on it for gears . I’d multiply motor KV times voltage (3.7V per cell) then apply the gearing. If you want to run 2000, then choose a pinion that will give you 2000~2050. If you find yourself loading the power system in the air and dropping rpms at times, then you need either another tooth on the pinion for more headroom, or first increase timing on the motor a few degrees (up to 20~25 degrees is fine as long as you monitor motor temperature and it doesn’t get too hot). You want the smallest pinion (deepest gearing) that you can use and still maintain the rpms you want to run without loading it down. Say if you’re using a 20 tooth pinion (just pulled that number out of the air, no relevance to real life), and you load the motor when you pull on the sticks hard. You try a 21 tooth and everything is great, no loading. You should go back to the 20 and increase timing to say 10 degrees advance (slightly raising the KV) and if everything is still good, drop it to 5 degrees. If you get loading, go back up to 7,…etc. The 21 tooth is slightly overgeared, the 20 tooth is slightly undergeared, and it’s not possible to have a 20 and a half tooth gear <G>. Timing changes to vary the KV will get you there. Motors tend to get warmer with raised timing, so you always have to keep that in mind, but this process will get you as optimized as possible. If you want to drop the rpms from there, and you can’t get a small enough pinion, then you need a lower KV motor. Also, different ESC’s have different algorithms for switching, and timing, so different ESC’s may require different gearing for this same process since they affect the KV. For instance, take a 450KV motor and run it unloaded to check KV with 10 different ESC’s. You’ll probably get 10 different KV’s, or at least 8 or 9. They’ll all be very close, but a little different.

Gary Wright

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08-19-2014 03:28 PM  3 years agoPost 32
gwright

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Champaign Il

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Additionally,.. back to your original question (sorry i diverged <G>, you'll have to find what low rpm is appropriate for your goblin 500 for yourself. I might like a certain rpm and you'll like another,..etc. There is no right or wrong answer,..it depends on your tastes. I've flown a few of those. One guy I fly with a lot has one, and neither of us liked it at low revs. Has to be screaming at 2000 or more. Smaller machines are like that. I have a 550 stretched to 600 (lightweight 6S setup) that I really only like at 1900~2000. It flies Ok at 1500~1600 but doesn't feel good to me, so I fly it at 2K and just live with the short flight times (7~8 minutes). I've flown another 600 that I really liked at 1650. Each machine is different so you have to find the low rpm that's right for you.

Gary Wright

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08-19-2014 03:30 PM  3 years agoPost 33
Rudy

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Houston TX/Bend OR

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1) How can I know what I can use for a pinion with out stressing my motor or esc? I would like to try some smaller pinions to bring my head speed down.
Well there are only three smaller pinions 15,16 and 17 teeth.

With my setup listed above I'm running a 2000 head speed.

Rudy Ackerman Houston TX/Bend OR

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08-19-2014 03:44 PM  3 years agoPost 34
HeliNutAndy

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worcester, MA USA

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Thank you for your help. I need to read through your suggestions a few times to make sense of it all... I am worried that the 500 is too small to experiment with. I have to decide on which 700 out there would fit my needs the best. I have already been through a few brands and I do like the Logos and Goblins. The Goblins might just be too heavy.

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08-19-2014 04:21 PM  3 years agoPost 35
gwright

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Champaign Il

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A little research turned up gear ratios with various pulleys. You're using an 18 which is 9.18 ratio, 1200kv motor and i assume 6S. (1200*22.2/9.18 = 2901 rpms available). Wow,..that's 900rpms of overhead. I bet you can cook an egg on the motor at the end of a flight <G>. With the 15 tooth it would be 1200*22.2/11.1 =2400 rpms possible. I'll bet that would result in the same flying style/power but things will be much cooler and flights a bit longer due to lower current peaks. If I were setting that up from scratch, knowing that 11.1 is the deepest gearing available and 2000 was the target rpms, I'd probably shoot for a 900kv motor which would result in exactly 2000 on the calculations. Then have a 16 tooth pulley available if there wasn't enough overhead. I like to start at the other end and work up rather than having things drastically overgeared and landing at molten temperatures before dropping pinion size.

As an example of mine, I'm flying an E550 raptor stretched to 600. 605 blades on it. I did want it higher rpms to have something different to play with for short flights and banging the sticks a bit. It's using an 850KV motor, 12 tooth pinion and 111 maingear, with 6S/5000. the math says 2040 rpms possible. I have three modes setup, the highest at 2000 and it doesn't load down even when I bend the sticks pretty hard (13/13 on pitch and 11/11 on cyclic on that little guy). I play around with lower rpms,.. 1500/1600/1800 in other flight modes, but I generally don't like little helicopters at low revs, so it stays screaming at 2000 most of the time and I just live with the short 7 to 8 minute flight times. the motor lands cool enough you can hold your hand on it indefinately, and if I want I can swap packs and fly continuously, no cool down period needed. I could probably play with gears and different kv motors and get another minute or so out of it but it's a beater that I try things with so I'm not spending the time to optimize it. It also has straight cut gears and I don't like the noise when going to little pinions.

Gary Wright

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08-19-2014 05:56 PM  3 years agoPost 36
turboomni

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East of the Equator

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I love the Goblin but hate the 5 minute flight times using a 6 5000 mah battery pack. I've tried to lower the head speed which isn't that high to begin with and the extra flight time is negligible. I get a solid 10 minutes with the Trex which is ideal for me. I just got rid of a Goblin 770 which had a 12 setup. I was getting close to 7.5 minutes with the 770 but I must have been drawing too much juice because my last flights with it was puffing my packs. I want to add another electric model to my fleet but really want to get at least 7 minutes a flight.
I have a Align 550 dfc that got 5 minute flight times. It had alot of power that I didn;t really need and wanted more flight time. I found the smallest pinion [10t] and went from 525 mm blades to 550 and bigger tail blades because of the low tail ratio [3.something to 1]. I dont run a gov but curves as I hear that is more efficient ,,I don't know. Lowered the the curves to 90-80-90. My flight times went up to 7.30 minutes. I keep the timer at 7 minutes to be safe. Still good power and no collective management needed at least with my style of flying. I might lower it alittle more and see what happens.

On my old align 450 that I converted to DFC I did a slightly different route. Smallest pinion running at 100% throttle in stunt modes but I use a 1350 mah pack. I extended the battery tray for perfect CG. The 1350 is half the weight of a 2100 mah pack. I backed off collective to the point it had the same pop or climb rate as the heavy pack. Same with cyclic abit. It is a much more efficient machine that does all the things on the small pack that the big pack did ,,but the disc loading is a good deal less. It has a light feel to it ,very nimble and precise. The flight times?? My timer is set at 5.20. Everything is cool. No stress on anything. If I run a 2100 mah pack flight times with all the same settings goes up to 7 + minutes but it does feel heavier and more sluggish.

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

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08-20-2014 12:52 AM  3 years agoPost 37
Kaolith

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Swanton, VT, USA

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Similar to using a 6s in a 12s system, would using a 3s 5000mah in my 6s 550e have an increase in flight time?

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08-20-2014 01:49 AM  3 years agoPost 38
gcm2

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Ft Worth, TX

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I was curious how any of you are fitting a 5000 mah batt in the Goblin 500? I'm using 4000's and they fit just fine, but I can't see how I would push a much larger 5000 in there. Thanks.

P.S. I LOVE flying my new Goblin 500, 4 minutes so be it...

TREX 700e, Goblins 500 & 570, DT520e, Gaui X3, Synergy E5

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08-20-2014 01:34 PM  3 years agoPost 39
HeliNutAndy

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worcester, MA USA

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I was curious how any of you are fitting a 5000 mah batt in the Goblin 500?
I purchased a few Pulse 5000 batteries for a 770 and they barely fit in the 5000. There is about 1/8 of an inch clearance between the motor shaft and battery. I am using an aftermarket battery tray that may add a bit of clearance I'm not sure. The tray makes sliding batteries in and out very easily(No this isn't a porn script)

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08-20-2014 02:17 PM  3 years agoPost 40
gwright

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Champaign Il

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Brings up an interesting observation.

What seems to get lost sometimes is the physical size and weight of various C-rating batteries. It seems most are of the mindset that higher C is better when it's really just different. It seems that most are interested only in the latest 1 million C battery because they think it's better, when for our purposes it's really just different (and much larger/heavier). If you discharge a pack at 10C that's a 6 minute discharge,.. 5C is a 12 minute discharge, 20C is a 3 minute discharge. Generally speaking, the lower C packs work for many of us, if not most of us, and they're lighter and sometimes smaller. they have higher energy density,..more watt minutes per gram. The higher C packs have higher power density,..totals watts they can deliver per gram. If you're running a sprint you want higher power density, if you're running a marathon you want higher energy density. An example are the two types of packs I use in most of my machines. I have 6s/5000's in both 50C and 30C. The 50C packs are 851 grams, the 30 packs are 814 grams. Yes, the 50C's are capable of 250 amps continuous and the 30's are only capable of 150 amps continuous (general rule of thumb is they're capable of twice the continuous in short bursts). My setups generally stay way under 100 amps during the peaks, and based on 12 minute average flight times to 4000 discharged, they're only drawing 20 amps average. the 30C packs are physically much smaller (they fit into the machines better), and they're capable of double what I'm drawing from them (much more in bursts), so why would I want the extra ounce and a third per pack for the higher C rating packs? Yes, 2 and a half ounces, while not immensely significant, is noticable on a 12S machine. In the past I even made a spreadsheet that compared average current from an eagletree (way before we had telemetry in the radios) and weight. With numerous flights logged you could see a clear constant to flight seconds versus grams of weight. By the way, I get a little neurotic sometimes about "knowing the numbers"
the only real downside is the lower C packs don't hold voltage quite as well under extreme loads. However, we're not loading to the extreme, and if you log the data, the difference is pretty insignificant.

The flip side is also true,..if you want to fly smack for 3 minutes, the lower C packs aren't going to work real well but that should be pretty obvious, and this thread is about higher flight times, not higher power, so we want energy density, not power density.

I can't wait on the new FP packs to arrive as the 30C 6S/5000's are 719 grams,.. for another 95 gram savings per pack, so the 12S machines will be another 6.6 ounces lighter compared to the current 30C packs,.. or half a pound if comparing to the current 50C packs.
Another benefit of using lower C packs is that in most cases they're much less expensive.

I just wish we could still get some of the old 10/15/20C packs. Energy density was really high.

Gary Wright

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HelicopterMain Discussion › Longer flight time model and setup choices
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