|Dec 17, 2012, 10:52 AM|
|Dec 17, 2012, 01:23 PM|
|Dec 17, 2012, 01:59 PM|
|Dec 17, 2012, 02:29 PM|
Probably pretty important for you guys in the warm country to have overhead... especially if you are flying back to back.
|Dec 17, 2012, 04:47 PM|
United States, TN, Knoxville
Joined Apr 2011
|Dec 17, 2012, 06:09 PM|
Starting Volts: 41.67v
WOT Volts: 37.04v
End Volts: 40.80v
WOT RPMs: 6635
WOT Watts: 4037W
WWOT Amps: 109.0A
Starting Volts: 41.82v
WOT Volts: 36.86v
End Volts: 41.22v
WOT RPMs: 6350
WOT Watts: 4984W
WWOT Amps: 135.2A
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.
|Dec 20, 2012, 04:27 PM|
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.
|Dec 20, 2012, 04:40 PM|
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.
|Dec 20, 2012, 06:22 PM|
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.
|Dec 20, 2012, 09:52 PM|
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
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))
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?
|Dec 20, 2012, 10:49 PM|
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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