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Old Dec 17, 2012, 09:04 AM
Facts, Logic, 3D
Tom K.'s Avatar
Florida
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You'll need more than a 450 if you're gonna fly more than once. Mine pulls 200+ a flight.

--Tom K.
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Old Dec 17, 2012, 09:08 AM
They Call him Dead!
YellowJacketsRC's Avatar
United States, SC, Pawleys Island
Joined Jul 2003
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What size do you use Tom?
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Old Dec 17, 2012, 09:52 AM
Facts, Logic, 3D
Tom K.'s Avatar
Florida
Joined Nov 2010
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Quote:
Originally Posted by Dead View Post
What size do you use Tom?
Either a 2100mAh 2S plugged into the receiver or a 1400mAh 3S on a BEC. We're changing over to the BEC w/3S to assure constant voltage to the servos (8.3-8.4 volts). I can fly 4-6 times before recharging and still be safe.

--Tom K.
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Old Dec 17, 2012, 11:38 AM
daedalusrobert's Avatar
United States, GA, Valdosta
Joined Jan 2009
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You guys using the BEC Pro on 3S as Aero posted earlier?
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Old Dec 17, 2012, 12:23 PM
Facts, Logic, 3D
Tom K.'s Avatar
Florida
Joined Nov 2010
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Quote:
Originally Posted by daedalusrobert View Post
You guys using the BEC Pro on 3S as Aero posted earlier?
No. We're currently just running a 2S into the receiver. We were going to go to 3S and the BEC pro but the BEC has too many wires and would require another 3 ports on the receiver and I only have 2. So for now we're going to stick with the current setup until we decide how we're going to move the receivers around and do some testing.

--Tom K.
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Old Dec 17, 2012, 12:59 PM
Not as Good as The Kid
Aeroplayin's Avatar
South Pasadena, FL
Joined Sep 2009
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Quote:
Originally Posted by bryansifsof44 View Post
According to the spec the 85 is only 2g more the 65 amp and gives you more options in the future. Not needed, but if speced weight is right why not. BEC is 5 amp should be enough, but they are digital servos which burn more power, so the external is a lightweight piece of mind.
I agree that headroom is your best friend with an ESC and I have seen a big difference in heat between cutting it close, to adding 20% or more to the constant current rating. I have an ESC with a burst rating of 80A on the 2820-680 on 4S with the 14x7 prop and I don't worry about a few grams at all, or the additional $10-$15 it costs. The 92 Amps that the 78 setup is pulling is doing so on a very cool Ice2 HV120. Also consider that we fly in Florida so a winter day could be 80 degrees. It's 77 degrees and sunny right now.
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Old Dec 17, 2012, 01:29 PM
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United States, AK, Anchorage
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Probably pretty important for you guys in the warm country to have overhead... especially if you are flying back to back.
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Old Dec 17, 2012, 01:32 PM
zürich
Joined Jun 2008
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aeroplayin....can you say anything about apc 24x12 vs meijzlik 24x10th ?
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Old Dec 17, 2012, 03:47 PM
Byron C
3DeltaFly's Avatar
United States, TN, Knoxville
Joined Apr 2011
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Quote:
Originally Posted by Tom K. View Post
No. We're currently just running a 2S into the receiver. We were going to go to 3S and the BEC pro but the BEC has too many wires and would require another 3 ports on the receiver and I only have 2. So for now we're going to stick with the current setup until we decide how we're going to move the receivers around and do some testing.

--Tom K.
Most everyone is using short 4" ~ 6" aileron servo extensions on the receiver side. I'm planning on changing those from straight extensions to short Ys' leads to get an extra couple of ports for plugging the CC BEC Pro (or a dual output A123 pack) into. That way there is an added advantage of spreading the receiver/servo supply current across the Spektrum AR8000's buss, i.e. between R.Ail and Aux-1 (L-Ail) ports. Or maybe you're using something that has different needs.

Byron C.
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Last edited by 3DeltaFly; Dec 17, 2012 at 03:54 PM. Reason: Addendum: short Y-extensions of AWG 20 or 22 wire size
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Old Dec 17, 2012, 05:09 PM
Not as Good as The Kid
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South Pasadena, FL
Joined Sep 2009
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Quote:
Originally Posted by long leng View Post
aeroplayin....can you say anything about apc 24x12 vs meijzlik 24x10th ?
We have the 2x10 Xoar PJN, the 24x12 Xoar PJN, and the 24x10TH Mejzlik. We tested all three on the ground first on 10S with the Hacker Q80-7M with the same 2x 40C 5S 5000mAh Sky Lipos:

24x10 Xoar:
Starting Volts: 41.67v
WOT Volts: 37.04v
End Volts: 40.80v
WOT RPMs: 6635
WOT Watts: 4037W
WWOT Amps: 109.0A

24x12 Xoar:
Starting Volts: 41.82v
WOT Volts: 36.86v
End Volts: 41.22v
WOT RPMs: 6350
WOT Watts: 4984W
WWOT Amps: 135.2A

24x10TH Mejzlik:
Starting Volts: 41.88v
WOT Volts: 38.03v
End Volts: 39.89v
WOT RPMs: 6570
WOT Watts: 4423W
WWOT Amps: 116.3A

Since the Xoar 24x12 produced a very hot power output on the 10S setup, and since we did not want to sacrifice any more of the already low 5 minute flight time, the The Mejzlik was the final choice.

If you went with the Q80-8M on 12S, I would probably suggest giving the 24x12 PJN another chance. My intent at this point is to find a 50cc airframe that can come in under 18 pounds with the 7M on 10S. I would not recommend the 7M for any 50-60cc size EF or 3DHS planes at this time.

Oh, and Tom tried the 24x10 Xoar in the air and immediately put the Mejzlik back on without hesitation.
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Old Dec 20, 2012, 03:27 PM
Not as Good as The Kid
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South Pasadena, FL
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The discussion on the owner's thread about the setup for the 70 EXP made me go back to the calculator. I came up with these comparisons. These are all relative at 81% Kv efficiency, and 3.7 volts per cell. I did this only because everyone's batteries are going to be different, and I think that 81 is a fair KvE average.

From experience, the KvE is higher on Hacker V2 motors so they may be at a slight disadvantage in this comparison, so you can keep that in mind. Flight time is calculated at 40% throttle, and all weights are relative to published battery and motor weights compared to Roger's all up weight of 10.33 pounds. I used the higher weight listed for the 6S 3300 than my actual lower weight to try to maintain an even par.

The 3.7v and 81% may also be a good indication of where the power systems will settle-in once the peak charges are off the batteries. Even though this is just a guess, it is based on some in-flight data we have accumulated this year, and it seems to coincide with what Bryan posted a few pages back.

DM4330-216: 12S 3300 20x8 @ 216Kv = 2955W, 67A, 7.0 mins = 278W/lb @ 10.61 lb (7765 RPMs peak and a wing loading of 24.45 oz./sq-ft)

DM4330-236: 10S 4000 20x10 @ 236Kv = 2790W, 75A, 7.0 mins = 262W/lb @ 10.66 lb (7075 RPMs peak and a wing loading of 24.56 oz./sq-ft)

A60-20S V2: 10S 4000 20x10 @ 245Kv = 3120W, 84A, 7.0 mins = 291W/lb @ 10.73 lb (7342 RPMs peak and a wing loading of 24.72 oz./sq-ft)

DM5320-300: 8S 4000 19x10 @ 310Kv = 26350W, 89A, 5.8 mins = 255W/lb @ 10.33 lb (7430 RPMs peak and a wing loading of 23.80 oz./sq-ft)

DM5320-300: 8S 4000 19x10 @ 300Kv = 2390W, 81A, 5.8 mins = 231W/lb @ 10.33 lb (7190 PRMs peak and a wing loading of 23.80 oz./sq-ft)

A60-5S V2: 8S 4400 20x10 @295Kv = 2788W, 94A, 6.4 mins = 259W/lb @ 10.29 lb (7075 RPMs peak and a wing loading of 23.71 oz./sq-ft)

A60-6XS V2: 6S 5300 20x10 @ 370Kv = 2321W, 104A, 6.1 mins = 230/lb @ 9.81 lb (6650 RPMs peak and a wing loading of 22.60 oz./sq-ft)

The more I look at these numbers, the more I understand why the A60-6XS V2 motor on 6S is so popular on this size airplane over at 3DHS. That's almost 240 Watts/lb with a wing loading under 23 on this plane if the wing area is correct. I think they are also putting the 21x10 or a 20x11 on 74 inch planes with success.

Considering Watts per pound and wing loading, I think the DM4330-216 on 12S, the A60-20S V2 on 10S, and the A60-5S V2 on 8S have big potential as excellent power setups in 10 to 11 pound planes.
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Old Dec 20, 2012, 03:40 PM
Not as Good as The Kid
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South Pasadena, FL
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I also forgot to mention that the 310Kv seemed to make more sense than 300Kv for the DM5320 motor according to Roger's numbers. I included calculations for both possibilities. Maybe the reality is somewhere in-between. Again, these numbers are for 3.7v/cell.
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Old Dec 20, 2012, 05:22 PM
Just flitting about!!
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Joined Aug 2011
2,637 Posts
Jim,
I'd much rather be flying one of these under the 10.5lb number then above.

My slick came in around 10.8lb and she was heavy and sluggish.

The 70" extra feels light and nimble by comparison and 6 minutes on 19x10 Xoar still had 28% left in the packs.

I am using pretty good 30C Gens 4s4000 packs though and the voltage sag is pretty minimal compared to other packs I've tried.

On the 19x10 Xoar it will peak at 3000W and settle to about 2800Watts after a few seconds. Losi also runs this motor and uses a Mej 19x8 gas prop and peaks around 3000W as well.
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Old Dec 20, 2012, 08:52 PM
bryansifsof44's Avatar
United States, AK, Anchorage
Joined Oct 2011
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We were talking (losi and I) about this the other day... to get those numbers we figured Losi has a wind closer to 330 then the 310 he thought he had. So roger if your getting numbers that high I assume you do too.

As far as my setup I believe it is slightly more efficient then stated above... Actual numbers below. Settled in numbers are 5-7 seconds in a WOT... after 5-6 WOT blips. Peak numbers are highest reading with each prop at one point in time.

Xoar 20x8 PJN
Weight 61g
Peak: 8102 RPM, 3180 watts, 71.3 amps, 44.6 volts
Settled in: 7947 RPM, 2863 watts, 65.5 amps, 43.7 volts
So with a 216kv motor efficiency is 84.1% (8102rpm / (216kv x 44.6V))

APC 20x8E
Weight 112g
Peak: 8167 RPM, 3123 watts, 69.8 amps, 44.8 volts
Settled in: 7990 RPM, 2749 amps, 63.1 amps 43.6 volts
Motor efficiency is 84.4% (8167RPM / (216kv x 44.8V))

Just for comparison Jim... What efficiency readings were you getting from the Hacker?
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Old Dec 20, 2012, 09:49 PM
bryansifsof44's Avatar
United States, AK, Anchorage
Joined Oct 2011
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Quote:
The more I look at these numbers, the more I understand why the A60-6XS V2 motor on 6S is so popular on this size airplane over at 3DHS. That's almost 240 Watts/lb with a wing loading under 23 on this plane if the wing area is correct. I think they are also putting the 21x10 or a 20x11 on 74 inch planes with success.
Joe Smith says here you need a 21" prop to get good power with the A60-6xs, which gives excessive torque on a 70" plane... good for 74" plane though according to him:
http://www.rcgroups.com/forums/showp...ostcount=26926

My setup is just under 3oz (under 0.2lbs) heavier then the A60-6xs setup with a 26.81oz 6s 5000 running on a 4.3oz Ice 100... motor spec is 17oz. Total 48.11 oz for power system

My setup: DM4330 spec weigh of motor 17.64oz... 2 x Glacier lipo 6s 2600 batteries at 14.6oz each, and a 4.2oz Ice 80HV. Total wight of my power system is 51.04oz

Difference of 2.93oz.
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