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Old 03-03-2014, 12:39 PM   #1 (permalink)
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Hello i'm building a A119 Koala with a 4 blade head and trex 600 mechanics. Im using the RCA Roban Head and 600mm Spinblades Asymmetrical.

I'm trying to achieve around a 1400rpm headspeed. I'm looking for suggestions for motor and esc combo using a 6s battery. I currently have a Ice2 80HV and a 600mx 510KV motor. But I don't think I'll be able to fit a 12s set up in the fuse.

Thanks,

AJ
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Old 03-03-2014, 07:19 PM   #2 (permalink)
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Hello:

This is what I would suggest. Keep with the 12s system if at all possible. What is the body kit you have? That will have an impact on what you can get away with. Having been through putting a multi-blade head on a 600 size helicopter and trying to run it on 6s, I would vote no today. There is extra lift generated but at the expense of a lot more drag created by the head. That, in turn, will tend to load up the motor and even with having a good gear ratio, it still will not help the situation. I didn't help things much by putting a full scale cockpit in the bird but the ESC was never able to keep the motor at a constant speed and the data logs were the proof of the pudding. They stunk.

I do use a 510kv motor with an 11t pinion and 112t main but even if I change the gear to the 118, it will be a bit of an improvement. I would switch your motor to a 450kv 700 size motor with at least 3300 watts at normal operational loads. My ill fated 6s only had 2600 and that was not enough for a 16 pound model and it would never have been enough for it when it bloated to 17 pounds. 1400rpm might work well with an empty body and it might work well with mine since I am using the same blades you are only with a five blade head. Make sure you have the grunt to do 1500rpm at the top end and if your tests show that you can do a full collective pullout without bogging the motor at 1400, then you can tune your motor setup even more. One last thing, the batteries you can use for a 12s system are a lot smaller than ones for a 700 size helicopter. I use 3300's and 4000's in my two 12s 600 size helicopters and they are fairly easy to fit in there. Hope this helps.

Don
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Old 03-03-2014, 07:40 PM   #3 (permalink)
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Thanks for the reply, I have a Marvelcraft A119 Koala. I guess i can try to fit a 12s setup in there. I'll try to dry fit everything and see how much room I have. I didn't have a problem fitting a 12s in my Jayhawk. This one is a narrower fuse.

Thanks,

AJ
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Old 03-03-2014, 10:22 PM   #4 (permalink)
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I had the same issue with my Huey. I didn't want to load up the cabin with a 12s setup so I decided to purchase the Align 600MX 1220KV motor to run on an 8000mah 6s battery. There are a couple of issues that you will have to address. My 600MX motor came with the 6mm shaft. Due to the size of the 6mm motor shaft it's difficult to find any pinion gears under 14t. The only ones I could find recently were 16t which puts my headspeed too high or my throttle curve too low. I tried running a Castle Talon 90 with integrated 20amp BEC running the electronics. Last Sunday I put about six flights on the helicopter and she flew beautifully but on the last flight I had a warning tone coming from the ESC and I'm pretty sure it was a thermo warning. The problem is that I'm running a 6s setup with a 14t pinion, my throttle curve is at 72%, I'm at the upper limit for what the Talon 90 is designed for and I'm adding addition stress and heat by running the electronics from the integrated BEC. My solution is to have a friend turn down a new motor shaft to accept 5mm pinion gears, switch to a 11t pinion and increase my throttle curve to get the same head speed that I have been flying at. Next I'm going to replace the Talon 90 with an Edge 130 ESC and run a separate Castle BEC Pro to power the electronics. That should give me some overhead on the ESC and eliminate the heat issue and still let me run the 6s setup.
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Old 03-04-2014, 12:17 AM   #5 (permalink)
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I just had a look at one 8000mAH 6s pack and was floored by the weight. Depending on the size, most 12s 600 battery systems are lighter with 3300's and the same or slightly more at 4000mAH. I kind of proved to myself what I had been told by a supplier that has been at this for over thirty years. What he told me was that when you use a 6s system where a 12s should be used, you will draw more power though the ESC, your motor will not be as efficient and convert that to heat, and the battery will have a lot more current drawn from it and start to internally heat up too much.

My experience with a heavy 6s helicopter was that the motor got really toasty, the 4000mAH pack got hot to the touch, and the ESC recorded some high internal temperatures. I went to a twin 4000 pack which lowered the current drawn from the individual battery but didn't change anything else, in fact, the motor got hotter, faster, carrying the extra battery. In the long run, it was a lot easier to make the switch, take the hit on the motor, and get cool running batteries, ESC, and motor, in one single stroke. I rarely draw more than 18 amps average with a maximum spike of 40. That could not be said for the 6s system. However, if it works to your liking, who am I to say it doesn't work for you. Hope you get lots of flights out of her.

Don
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Old 03-04-2014, 07:54 PM   #6 (permalink)
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I agree with everything Don mentioned in the previous post. Yes the amp draw is going to be higher on a 6s setup but if geared properly and using an ESC with plenty of headroom and a separate BEC there shouldn't be any problem flying on 6s. 5000mah 6S batteries use to be the standard for most 600 size 3D helicopters until all the pros started putting higher power setups into their birds. An 8000mah 6S battery shouldn't break a sweat on a 100-120 amp draw. On the other hand the 4S 2200mah batteries I use in my 200mph pylon racer that draws about 100amps usually come out quite toasty after landing.

Ultimately I chose to go with a 6S setup in my Huey because it was easier to install and conceal one large battery in the cabin. The funny thing is that even though I have an 8000mah 6S battery installed forward of the CG, I still needed nearly a pound of lead in the nose of the helicopter to achieve the correct CG. If I didn't care about installing a scale cockpit and cabin, I would have used two 4000-5000mah 5-6s batteries in series for a 12S setup which is what I use in my 700 size MD500.

I've come to learn that most scale aircraft regardless of whether it's an airplane of helicopter are going to need some added weight to achieve the proper CG. It just seems to come with the territory when getting into scale aircraft.
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Old 03-04-2014, 09:03 PM   #7 (permalink)
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Tell me what you guys think of this setup.

I will be running a 4 Blade Head with the spinblades asymmetrical 600mm.
Hyperion 4025 740kv
15t pinion
CC 100a esc
WR Hercules BEC
6s 5000mah

I used the headspeed calculator and this should give me around 1500rpms at 100%

Thanks,

AJ
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Old 03-04-2014, 10:48 PM   #8 (permalink)
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I don't know what calculator you used but I am only getting 1308rpm at 100% with that setup. Is there something I am missing? Here is another suggestion before you get too far. Most good ESC's have the capability of easily being used as a governor for the motor. In a perfect setup, you try to get your desired head speed at 92% of full rpm. That way, your system will have some overhead and if you need a few extra rpm, you can get it by overriding the suggested warning about no overhead. I tired an 890kv motor in my 500 which was a very heavy little pig. The same motor is in my Jet Ranger and it performs flawlessly but it is a number of pounds lighter. If you keep the weight down, the 890kv motor with a 16t pinion and 170t main will spin the mains at 1550 at 92.5% of full throttle. It puts out 2700 watts vs. the 2800 watts of the 740 but to get the same rpm, you would need an 18t pinion running the motor flat out to get 1500rpm, which is not a good idea. I have not seen a pinion higher than 16t for a 6mm shaft but there are some rather large pinions from Mikado but for 5mm shafts only. Have another look at your calculator inputs. Don't rush this so take your time and see if you have things as you need them. Take care.

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Old 03-05-2014, 04:05 AM   #9 (permalink)
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I agree with Don's calcs (I get 1304rpm), but I assumed a 170T main gear as I don't think I saw a main gear specified. My guess is you used MrMel's calculator without clicking the CC governor box as it always gives higher speeds.

So either a faster motor or larger pinion is probably required, or stick with the 12s setup, and smaller lipos (maybe 2x 3000mAh).

I would suggest around 1300 to 1350rpm, especially with Spin asymmetrical blades, which are a lot wider and more lift than normal blades. I run my 12s 600 sized Seahawk (19lbs, Xera 4030-470kV, CC Ice 2 80HV, 2x 5000mAh 6s, 4x 600mm GF symmetrical main blades & 4x 105mm tail blades) at 1350rpm and it flies quite well.

If you fly in true gentle scale fashion, your 80Hv would do, even on 6s. My Seahawk usually draws about 22-25A, with peaks up to 36A, so a smaller lighter heli flown the same way on 6s should draw between 35 and 60A. The 80Hv will handle short peaks of 120A or more.

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Old 03-05-2014, 05:42 AM   #10 (permalink)
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This is all good info. So just to sum it up. Looks like I'm going to need an 890kv motor with a 16 tooth pinion. I'm looking at Hyperion 4025 which has a 5mm shaft so higher tooth pinion would be easy to find. I also have a 910kv Motor laying around. I should be able to use the 80hv with either one correct?

I did run Mr Mel's Headspeed calculator without the gov. So it did show a higher headspeed.

Also I would've kept my 12s setup if I could find room to strap the battery in.

Thanks Guys!!!

AJ

Last edited by aja1216; 03-05-2014 at 09:28 AM..
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Old 03-05-2014, 12:29 PM   #11 (permalink)
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You can use the 890kv motor with the 80HV and you can also use the 910kv motor as it is not a big jump and as long as it is in good shape, it should do just fine. In fact, with the 170t main and a 13t pinion, at a governed 92.5%, you end up with a rotor speed of 1398. You can easily change the pinion to a 14t to get a bit more head speed if 1400 seems too mushy and as good as a rotor can sound at lower speeds, a mushy flight characteristic is something you really don't want. By the way, which set of blades do you have? I have the 5 blade grey set and they are 35mm wide which are the same width as the 4 blade set. Take care.

Don
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Old 03-05-2014, 01:53 PM   #12 (permalink)
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These are the blades I purchased

http://www.allerc.com/spinblades-asy...mm-p-7495.html

First time i'm using them but I've read good things about them.

Thanks for the input, I really appreciate it!!!
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Old 03-05-2014, 10:39 PM   #13 (permalink)
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Just some info that might help.

I have a 14 lb heli running 2 690mm blades (not multi blade head so not sure if this helps) It is running on a single 6s 5300mah battery (electronics all powered by their own 2s life pack). Motor is Kontronik 650-780kv, 17T pinion, and Kontronik 80LV ESC. 164T mod 0.7 main gear. I can regulate the headspeed down to 1500-1600 rpm when need be with the throttle curves, but I usually run around 1600-1700 rpm. I set my timer to 7 min, fly nice slow scale circuits, and put about 3200 mah back in the pack. In wind I max it out and get between 1800-1900 (although I set my timer to a short 5 min to be safe)

The battery, esc and motor all come down cool to the touch. With over 200 flights on this heli nothing has ever so much as been warm to the touch.
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Old 03-06-2014, 04:08 AM   #14 (permalink)
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Quote:
Originally Posted by pc3associate View Post
Just some info that might help.

I have a 14 lb heli running 2 690mm blades (not multi blade head so not sure if this helps) It is running on a single 6s 5300mah battery (electronics all powered by their own 2s life pack). Motor is Kontronik 650-780kv, 17T pinion, and Kontronik 80LV ESC. 164T mod 0.7 main gear. I can regulate the headspeed down to 1500-1600 rpm when need be with the throttle curves, but I usually run around 1600-1700 rpm. I set my timer to 7 min, fly nice slow scale circuits, and put about 3200 mah back in the pack. In wind I max it out and get between 1800-1900 (although I set my timer to a short 5 min to be safe)

The battery, esc and motor all come down cool to the touch. With over 200 flights on this heli nothing has ever so much as been warm to the touch.
I think you could improve your flight times a fair bit by dropping the headspeed a few hundred rpm. 1700rpm is very fast for a scale 700 heli.

My Vario Long Ranger (19lbs, 2x 710mm mains, 2x 120mm tail, 12s) runs at 1350rpm and I get a very easy 12 minutes (2x 6 minutes) and put back around 3500mAh into the lipos.

I run my 2 blade 500 sized UH-1N at 1700rpm.

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Old 03-07-2014, 05:50 AM   #15 (permalink)
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Do you think 2 6s 2650 would work seems like they would be a better fit. As far as flight time I'm ok with around 5 to 6 mins.

Last edited by aja1216; 03-07-2014 at 02:04 PM..
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Old 03-07-2014, 10:28 AM   #16 (permalink)
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Quote: Do you think 2 6s 2650 would work seems like they would be a better fit. As far as flight time I'm ok with around 5 to 6 mins.

AJ :end of Quote



A lot will depend on your final weight. I have two 12s scale helis and each takes a different charge for the same time in the air because of that, blades, and drag. My TOW Defender is the heavy one and has the higher blade count plus the fact that the doors are wide open and most of the rear door is too. The AS350 is fully closed in with a couple of air openings in the windows, the doghouse, and a large one on the bottom. It is quite a bit lighter than the TD. My TD takes an average of a 2300mAH recharge per pack for a 6 minute flight plus spool-up whereas the AS350 takes an1800mAH recharge per pack. I use 4000's in my TD and 3300's in my AS350. I can easily push them to 10 minutes in the air but unless there is an emergency on the field, I don't bother. Based on what my AS350 gets (about 13 pounds RTF), you would get away with that but you would be pressed to land every time as that pack would only get you a maximum delivery of 2120mAH per pack and in my books, that is cutting it a bit close.

I know you will be getting a thin body but from what I remember of those bodies, there is a lot of room in front of the chassis and you end up needing nose weight anyway. I am fairly sure that you could put a two seat cockpit in and build a box around the batteries mounted just behind the cockpit to simulate a load being carried. You could do the same with a 6s battery too, but first you need to actually start the build to see where you really will end up at. This is completely guesswork until you get the chassis and body in the same place and measure it out. You don't need to get the matching motor, gearing, batteries, and ESC until you see what room you have to work with. The rest you can go nuts with and get it ready for all that so once you are ready to put the motor in, you will see what room you have for batteries. There is no reason that a battery can't be mounted in the original chassis and the second one stacked in front of it. That has been done with many chassis just to test them out. Let's see what you get. Take care.

Don
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Old 03-07-2014, 02:03 PM   #17 (permalink)
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You guys are awesome!!! For now I will keep the 12s setup I will get the mechanics up and running then I'll revisit how to fit everything in. I think I'm going about the process the wrong way.

Thanks Don and Colin and the others that responded. I'll post the progress on here.

AJ
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Old 03-09-2014, 05:02 AM   #18 (permalink)
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OK, some data in addition to what Don posted.

My LR (12s, 19lbs, 2x 710mm, 1350rpm)
Typically between 300 and 320mAh per minute (depends on how much I hover) - I would get an easy 6-6 minutes on a pair of 2650mAh.

My Seahawk (19-20lbs, 4x 600mm, 1350rpm)
Typically between 370 and 400mAh per minute (depends on how much I hover) - I would get an easy 5-5 minutes on a pair of 2650mAh.

Don makes a good point about the weight though. On my Seahawk, which is a notoriously tail heavy fuselage, even with 2x 5000mAh 6s and 2x 2s A123 hanging off the front of the Chaos 600 mechanics (touching the cockpit seats) which is almost 2kg of batteries, I still needed about 500 grams of weight bolted in under the cockpit.

A bit less of a problem with the Long Ranger, and the lipos sit on the floor on either side of the mechanics, I needed about 200 grams (from memory - lots of sleeps ago) to get it balanced.

If you get creative, you will probably find a way to get the lipos in, even if it is not exactly scale.

If you do go for smaller lipos, I would tend to get 3000 or 3300mAh. Also remember that the smaller the lipo, the higher the C rating required. For 5000mAh, 25C is fine, for 3000-3300mAh, I would lean towards 30C, and for 2650mAh, I would lean towards 35-40C.

Colin
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Old 03-12-2014, 11:14 PM   #19 (permalink)
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I'm happy to say my new 6s setup worked well in my Huey. I'm spinning a pair of 690 mains with a stock Align 600MX 1220kv motor using a Castle Edge 130 ESC with separate Castle BEC Pro tapped off the 8000mah 6s flight pack. I had a friend turn down the stock 6mm shaft to 5mm so that I could run an 11T pinion which enables me to setup my throttle curve at 80% for scale flight. Everything stays pretty cool now that I have made the changes. The helicopter weighs in at about 14lbs and I have nearly 500 grams of lead in the nose to achieve CG. I'm very happy with her performance.
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Old 03-13-2014, 04:38 PM   #20 (permalink)
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Awesome Big!!!! I'm gonna try it with a 12s and see how it is. I do have a cockpit so we'll see if it fits.

My new problem is a longer main shaft looks like I'm gonna need another 10-15mm for the J arms of the head to clear.

AJ
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