12S power systems ideas and options

[Aeroplayin]

The great thing about electrics is that needed weight in the nose can always translates to more flight time. With most batteries, each 250mAh will add about 2.6 to 2.8 ounces. So each 750mAh added means about 8 ounces added, and in this size plane, that can mean another full minute of flight time. It will take some figuring out to get over the initial change from a 5Ah to 5.3 Ah configuration, but it can be done.

 

[skibum44]

Bryan, I used a dab of 5min epoxy to secure the temp probe to the baseplate... Seems to give me decent data so far.

Mine is pretty secure in the mesh fastened at the front and back of the ESC. Tested with batts at storage and voltage and no load RPM from the telemetry gave me 187.5kV for the 5335.

 

[skibum44]

Very clean install. Let us know how the CG works out. The 91s are notoriously tail heavy in DA-60 setups and I wonder if the electric works out well.

Thanks... Will do on the CG. I think I will be ok having the batteries at the firewall, but I will know soon enough.

 

[Enterprise]

I was reading some of the back and forth on a RCG thread on the new MXS power system, and the guess is that they are running a 5335 on it.

So my question is, for a 12s 3300 setup, I see three current choices mentioned

4330-206
Hacker A60-8S
5335-195

Now these all go up in power as you go down the list. Which one will be the more efficient though? Is the running 5335 not as hard as it's amp rating allows offset it's additional mass. Is the 28 pole hacker going to shine in efficiency?

Flight time is always the downfall of the electric, and I would like to maximize this within reason as I am a throttle hog at times.

 

[gyro]

I'm relatively certain it has a Motrolfly in it, and a ZTW HV ESC.

 

[Aeroplayin]

I was reading some of the back and forth on a RCG thread on the new MXS power system, and the guess is that they are running a 5335 on it.

So my question is, for a 12s 3300 setup, I see three current choices mentioned

4330-206
Hacker A60-8S
5335-195

Now these all go up in power as you go down the list. Which one will be the more efficient though? Is the running 5335 not as hard as it's amp rating allows offset it's additional mass. Is the 28 pole hacker going to shine in efficiency?

Flight time is always the downfall of the electric, and I would like to maximize this within reason as I am a throttle hog at times.

We're seeing 28 pounds on the 22x10E Mejzlik on the DM5335-189Kv. Two tests.... Settled in at 4407 Watts and 98.3A on the first test to 7186 RPMs and 4578W and 100.79A on the second to 7244 RPMs. This is really nice, but I'd consider a 23x9 Falcon on it just to slow things up a bit, or go to the 195Kv with the 22x10E or PJN.

The DM4330-216 and the A60-7S on 12S needs a 20x8, no doubt... this will pull only 21.4 to 21.7 pounds. I have a 206Kv and tried the 21x8 PJN on it and got about the same pull. Both are doing about 3100W and 68.56A peak and settling in at about 2725W and 61 to 63 Amps.... 7425 to 7540 RPMs.

We're still waiting for a pull measurement on the A60-8S on 12S with the 21x10 and the 22x10 Mejzlik E-L, which is 45.5g, but seems to be a little stressful on 12S. Throttle response is reported as very good tho. I'll keep you posted once we hear something, but that motor is not doing much more than 3100 Watts either.

The AUW of the DM5335 is 1004g compared to 571g for the DM4330 and 679g for the 28 pole A60 S.

My DM4330 and my A60-7S on 12S are both great on 10.8 pound planes, and I'd put them in the two new 74 inch EXPs in a heartbeat, but I'd go to the DM5335 on the MXS if for no other reason than it is really a 50cc airframe at 85 inches.

 

[Aeroplayin]

To clarify a few things, my guess is that the AUW of this plane is going to be 14 pounds with 2x 4400 6S batts, plus whatever the wing extensions are. Let’s say 14.25 lbs, 14.32 with a CF 23x9 Falcon prop option, and let’s estimate that the 85 inch wingspan comes out to a 1290 sq-in wing area. That’s a wing cube loading just under 9, which is what we are all flying right now on the 78 and the 91 Extras. So, perfect, IMO.

Either of the two prop option will still produce a 2-to-1 thrust-to-weight, 270 to 290 Watts per pound, with a 6 minute flight time, at a 26 oz/sq-ft wing loading.

98A with a 4400mAh capacity:
98A / 4.4Ah = 22.3C
60 minutes / 22.3C = 2.69 mins at WOT
2.69 mins x 0.8 safe capacity = 2.16 mins at WOT
~35% power average (2.16/.35) = ~6.2 minutes

Everyone's power average is different but this seems to be the value with most of the contributors on the power thread. Tom's about a .44 so he would need 5300mAh for 6 mins, which would add 180g or 0.4 pounds, which would screw everything up. :sadface:

I’d try both props to see which one gives me the best blend of throttle response, pull-out, and top-end speed and go with it. I’m fairly sure this will be a really fun plane if the AUW is real, and even better if I've overestimated.

The other option is to go with the lighter motors and 3300's and bring this plane in at 12.7 pounds, probably, but it will be a very busy motor at about 220 to 230 Watts per pound on an 85 inch wing. You'll be spinning a decent 21 inch beechwood or CF prop max because the 22's do load these A60 and DM4330 systems a bit too much (IMO). I would be curious to see what a WL of 23 and WCL of just under 8 would be like at 1.7-to-1 thrust to weight tho. Probably nice and floatie, but not very dynamic.

 

[Enterprise]

I keep leaning towards the lighter options with 3300 or 3700 as I have those batts. I suppose the question is 4330-206 versus the 8S. Is the extra 100 grams and 28 poles gain me anything?

 

[Aeroplayin]

Good question, and this is all I have to offer at this point.

I'm on the 215Kv A60-7S with 12S right now and there is no way I'd use a 20x8 prop on anything bigger than the 74 at under 11 pounds only because all the power is at the top end.

When I ran the 10S setup on the same motor and plane with the 21x10 Falcon beech, I was obviously getting more power in the low and mid ranges... taking off at 1/4 throttle, KE circles and rolling circles at half. With the 21x10 on 12S with the 188Kv, I'd have to see 7100 RPMs with no commutation issues in order to see the 24 pounds I feel I'd want in order to consider the motor on the 78 Extra or the 85 MXS. The 78 Extra will come in at 12.6 pounds with the Hacker A60-8S 188Kv on 3300's if you go light with the BEC instead of an Rx batt. The video of Tom flying the electric converted gas version of the 78 at the Deland Huckfest was with the A60-16M on 10S with a 22x10 PJN and the heavy cage mount to right at 14 pounds, and the motor was pulling 24 pounds on the Rapala in a static test. This is the video.

[video=youtube;M4Ul6tsDgLU]https://www.youtube.com/watch?v=M4Ul6tsDgLU[/video]

 

[Enterprise]

How does the 4330-206 run on the 21x10? I also see Ken has a 195kv option on this motor as well. I am setting up a Pilot Sbach electric for my A60-6XS, but maybe I should use it as a test bed for these setups. It will be stupid over powered on 12S.