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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 11-23-2007, 02:02 AM   #1
fiveoboy01
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Default Thoughts on running 4s?

I'm thinking about switching to a 4s setup on my trex.

I'd end up ditching the JGF motor and going with something like one of the scorpion motors at the 4500ish kv.

Questions:

How bad is the weight penalty? Does it cause any major CG issues?

What esc would be recommended(amperage)? It has to be a CC esc, because I'm spoiled by the Castle Link. I'm running a Phoenix 35 right now, would a 45 cut the mustard? Or would I want larger than that for a safety margain?

I'm assuming the woodies aren't safe at real high headspeeds. I've been running 2800 on mine for many flights now with no issues, but I'm unaware of their maximum rated rpm. Will v-blades be safe up to(or exceeding) 3300?
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Old 11-23-2007, 02:41 AM   #2
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4500KV is the wrong type of motor for 4S. A cc p35 is overkill, remember higher voltage will mean a lower current.
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Old 11-23-2007, 06:28 AM   #3
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HFG how does a higher voltage give you a lower current? Is it not I=V/R (ohm's law), so if you increase the volts (r stays the same) you will increase the Amps?
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Old 11-23-2007, 07:09 AM   #4
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The brushless motor will always try to spin at its nominal speed for the applied volts. What varies is the power required for it to attain that speed. The power required to spin the blades at a given RPM and pitch is almost constant (other than parasitic I^2R losses). Thus at a higher voltage, for any given headspeed, less current will be drawn to provide the necessary power.

Going to 4s you want a lower KV motor since you have 33% higher voltage. Even if you want a higher headspeed, that will be achieved with a combination of voltage, KV and pinion.

3300rpm is really much higher than needed, even for wild 3D. Around 3000rpm is all you really need. The woodies are only rated to 2400rpm but many people fly them at 3000rpm with very rarely reported problems. It is a safety issue and good quality CF blades are certainly recommended. Metal blade grips are a must have item at those headspeeds.

So a reasonable 4s setup is probably something around 3000KV with an 11t pinion. However if you do a search you will find many recommendations for 4s setups with specific motor/pinion combinations.

As for weight, a 4s 1800 weighs about the same as a 3s 2200 with about 9% more energy so will give longer flights at the same headspeed.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
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Old 11-23-2007, 08:08 AM   #5
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Jazz 40 6 18
Thunder Power 4S2100 Prolites (180g) or Flight power 2100 EVOLITE (210 grams)

Go check out Trextuning 4S supertest.
Most of the winning motors are still the ones to get, maybe another Neu has slipped in as well. Just watch the weight of the motor ,this is where some good setups come unstuck (the weight issue).

I can thoroughly recommend the Medusa 28 32 2800, with an 11 tooth pinion 3200HS at full noise for the full flight of 7 minutes, 2900 HS for 9 minutes or 2600 for 11 minutes.

Mick



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Old 11-23-2007, 08:43 AM   #6
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I have Jazz 40 6 18 / Medusa 28 40 2500 100g / 12 tooth and run 30sec to a 1 minute less than Aussiemicks set-up but with 4S TP2070 217g / 4S Hyperion Litestorm 195g / 4SFP 2100 Evolites 210g.

They say there is no turning back on a 4S set-up and I agree.
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Old 11-23-2007, 12:10 PM   #7
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Ok thanks for the replies guys...

So do you think I'd be ok keeping my JGF motor? It's a 500TH(3550kv). I'm running a 13t pinion and seeing 2820 rpm right now... I can always step it down a couple teeth. Working backwards with a headspeed calculator and my current setup, if I bump up one cell and reduce the pinion to 11t, I'd see roughly 3200 rpm.

I do have metal grips already, wouldn't think of running plastic ones at high rpms. Definitely would switch to some carbon blades.

Will the 35 esc be ok here, or no? Sorry for the questions but I'm still sucky at electric stuff especially doing all the calculations.
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Old 11-23-2007, 12:28 PM   #8
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The JGF500 on 4s is a great motor. Run it with an 11 tooth pinion for high headspeeds and lots of fun. I flew a Mini Titan with this setup and it was a rocket. Temps and times were both very reasonable.

I am flying the Scorpion 2221-8 w/11 tooth on 4s with EVOLite 2100s. I am running the CC35 too. I tached it yesterday at 75% flat idle it was ~3050. At 80% it was ~3125 and ~3200 at 85%. 80% flat idle seems to be a good compromise that gave me 5 min flights using less than 1400mah with very low temps. All headspeeds were measured in a hover with a skytach within the 1st minute of a freshly charged lipo.
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Old 11-23-2007, 04:57 PM   #9
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Quote:
Originally Posted by Funky View Post
I am flying on 4s with EVOLite 2100s.
Hey Funky

Have you ever weighed your FP EVOlites? If so, how heavy are they?

Mick
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Old 11-23-2007, 05:27 PM   #10
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Yes... and I am kind of dissapointed. The weight is supposed to be about the same as my old 2170s, but instead they weighed 202 with deans connector. Weight isn't up too much from my 3s setup. I was running the Align ESC and FP EVO25s for a little under 810 grams. The new setup has a CC35 with a Medusa BEC for 836 grams with the 2100s.

They still fly good though so I won't pass judgement until I see how many cycles I get from these lipos. I am picking up 2 more 4s lipos next week but I am trying to decide on 2 more EVOlites, 2 Prolites or 2 Align 16C 4 cell lipos.



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Old 11-23-2007, 05:58 PM   #11
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Funky, are you then using the governor mode with the CC 35? Or just running a curve that tops at 80% on each end of the V-curve?
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Old 11-23-2007, 06:03 PM   #12
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I am running a flat curve so far (80,80,80,80,80), (90,90,90,90,90), etc. I am not running gov mode yet, but that is what I am testing these curves for. CC wants you to match the gov mode headspeed to the headspeed reached between 75% and 85% in fixed endpoint mode to get the best performance from the CC govener which is the reason for these low curves I am testing.

I have always been "against" gov mode on 3s. I always flew high, flat curves. 95% always worked best for me with my old Align ESC and 3s setup. I am very anxious to see how gov mode works out with the CC. It was VERY dissapointing when I tried testing the Align gov mode
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Old 11-23-2007, 06:05 PM   #13
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You got light ones!!
I haven't flown with my FP's yet , hopefully they deliver good power when the time comes.

For some reason it is getting hard to track down 4STP2100Prolites.

I can get the CG to work well with both types, The FP's must slide back about 20mm compared to the TP. If I really wanted to lose some weight from the heli I could ditch the EagleTree logger. But the 4S setup more than compensates for any increase in the weight. This thing pulls harder than a 14 year old school boy.

Mick
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Old 11-23-2007, 06:13 PM   #14
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How much do the heavy EVOLites weigh? I am really tempted to just go for Prolites or Aligns for my next 2 batteries. I know the 22c lipos are junk but my Align 16c lipos have over 200 logged cycles and are still flying and balancing great. I have tried MANY lipos, but none of them have lasted as long as these 2 lipos.... and they actually weigh what they are supposed to weigh

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Old 11-23-2007, 06:20 PM   #15
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I got 4 FP's during the week.

the average weight is 209 grams, the worst was 210 the best 208 with deans connectors.

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Old 11-23-2007, 06:23 PM   #16
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How much do your TPs weigh?

I may have slightly lighter ones.... but we are both a far cry from the 185g advertised wieght

I can't really feel a difference in overall weight from my old setup... although it is a LOT more powerfull so I can't compare it fairly. On my old 3s setup, I could feel a weight difference in the air between running 185g 2170s and my 145g Align packs. The power of the EVO packs definately helped make up for the difference and made me prefer them.... but not by as much as I would have guessed.
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Old 11-23-2007, 06:34 PM   #17
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I just weighed them
I have 6 TP's and they all weigh 188 grams with deans.

I too have my original Align 3S2100 16C lipo. It hasnt been used for 3 months since I crashed and decided not to rebuild my Aplus400. If I had of seen this ad http://www.grandrc.com/inc/sdetail/39546 I may have got 4. the price is fantastic.

Mick
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Old 11-23-2007, 06:38 PM   #18
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Exactly the ad I was looking at My only concern is how old these lipos could be. Not many people fly 4s so these lipos may have been sitting there for a year... or more. I know lipos hold their charges well, but I have already been burned with old lipos which held about 20% less than their specified capacity. They were "new" although they had been on a shelf for a little over a year. If I knew these 4s aligns were new lipos (from the past 3 months or so) I wouldn't have to think twice about ordering them.

Thanks for the info Mick
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Old 11-23-2007, 06:39 PM   #19
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And they have 16 in stock!!!
MIck
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Old 11-23-2007, 06:49 PM   #20
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Get 1, if it is ok then order a few more.
If you order now you would have a test fly by Wednesday or so. Then capacity check them. If they are up to scratch by a few more.

For $70 it is a fairly safe experiment. For me the shipping costs kill little experiments.

Mick
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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.

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