Power system for big 3D plane - RC Groups
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Feb 23, 2003, 10:00 PM
Registered User
Bill Mixon's Avatar

Power system for big 3D plane

I would like to get everyone's input on a power system for my giant 3D plane pictured below.

Plane specs..
Wing span 87"
Wing area approx. 1600
Length 76" from firewall to tip of rudder.
Weight as pictured with all radio gear, receiver battery, control linkages etc.. 2004 grams or
70.69 oz. or
4.418 lbs

I would like to use 20-24 cells and swing an APC prop in the range of 20X8 to 24X12.

That's a Hangar 9 Pizazz in the picture for reference, although it really doesn't represent the size that well.

More pictures and info in the Large 3D Plane thread in sport planes.


Last edited by Bill Mixon; Apr 19, 2003 at 09:37 PM.
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Feb 24, 2003, 01:45 AM
Our Daddy and Heli Junkie
Fred Bronk's Avatar
Very doable even with a single motor. I played with motocalc (you can to for free!)

I see better than a 2;1 power ratio at WOT

Motor: Hacker B50 10XL; 1578rpm/V; 0.0118 Ohms; 1.24A idle.
Battery: Sanyo HR 2600 nimh; 20 to 24 cells; 2600mAh @ 1.1V; 0.0045 Ohms/cell.
Speed Control: Astro 210; 0.003 Ohms; High rate.
Drive System: Model Electronics 6:1 Gearbox; 20x8 to 24x12 (Pconst=1.18; Tconst=0.995) geared 6:1.
Airframe: 3D; 1600sq.in; 123.7 to 132.1oz; 11.1 to 11.9oz/sq.ft; Cd=0.057; Cl=0.46; Clopt=0.66; Clmax=1.24.

NC = 24
Gear Ratio = 6.00
Diam (in) = 24.0
Pitch (in) = 12.0
Weight (oz) = 132.1
Batt Amps = 82.0
Motor Amps = 82.0
Motor Volts = 17.3
Input (W) = 1418.5
Output (W) = 1278.6
Loss (W) = 139.9
Temp (°F) = 263.5
Motor Ef(%) = 90.1
Motor RPM = 24980
InPLd (W/lb) = 171.8
OutPLd (W/lb) = 154.8
Elect Ef(%) = 59.1
Prop RPM = 4163
Thrust (oz) = 293.6
PSpd (mph) = 47.3
Time (m:s) = 1:54
Feb 24, 2003, 08:16 AM
Registered User
747drvr's Avatar
What kind of performance are you looking for ? A real tree stump pulling system is the one being used in the 30 cell Funtanas but your looking at a bit of cash.

I'm hoping to start a Funtana soon and am leaning towards a large " outrunner style" such as the Actro 40-5. I'm also looking at a Torcman or LRK outrunner but need to educate myself in their specs. The outrunners are a little heavier and less efficient than a big geared Hacker but at least there's no GB noise. The performance will still be more than "adequate" !
Feb 24, 2003, 11:20 AM
Registered User
Bill Mixon's Avatar
Thanks for running the numbers, Fred.
I think the amps need to go down and the time go up.

This plane is relatively light for it's size and ready to fly it should weigh around 8 lbs or so depending on # of cells, gearbox, etc. So 12-14 lbs of thrust should be good I think. I should be able to get away with a low pitch speed because of the light wing loading and type of flying I'll be doing with it. I didn't design the plane to fly fast or do large pattern type flight, but instead fly nice and slow 3D maneuvers, and hover.
Emphasis will be on keeping the plane as light as possible, flight times around 7 mins, and good hover performance.
Hover performance meaning the pecentage of total flight time that the plane will still hover.
For example: If I were to get a typical flight of 6 mins, 3 mins of hovering out of that 6 would be nice.
A 6 min flight with 1 min hover duration just wouldn't cut it.

I'm waiting to see the info on the new Hacker motor, but I doubt that I will need that much power for this plane.

From what I have read, some of the 60-90 size arf kits out of the box(just the unassembled airframe parts) weigh about the same as my plane with it assembled and radio installed.

Feb 24, 2003, 12:59 PM
Registered User
WimH's Avatar
Originally posted by 747drvr
I'm also looking at a Torcman or LRK outrunner but need to educate myself in their specs.
Here's a good starting point:

All-wood CNC Kit
Manufacturer: Harald Weiershäuser, Deutschland
Builder:Thomas Häni, Winterthur
Pilot :Thomas Häni, Winterthur
Span : 2m
Lenght : 2m
Surface Area: 1m^2
Weight : 4.4kg
Motor: LRK Torcman 430-30-15 (weighs 500g)
Prop: Aeronaut CAM 17x9 on 68mm yoke( Pic shows different one?)
Cells: 22xSanyo CP2400 "zapped"
ESC: Hacker Jeti Master 77
P_in 1300 Watt (22V, 59A)
P_out ca. 1050 Watt @ 6500 rpm ( Eff. >80%?)

Last edited by WimH; Feb 24, 2003 at 01:05 PM.
Feb 24, 2003, 04:24 PM
Registered User
747drvr's Avatar
Thanks Wim !

I'm aware of that sight and have seen this example of the Funtana. I would like to use 30 cells like the Funtanas that are flying in the US. The Actro 40-5 should work but I'm trying to figure out which Torcman would also work. I suspect the 430-30-?. They say that 10 poles is required for over 24 cells as well.

I would like to know how they compare to the Actro outrunners.
Feb 24, 2003, 06:19 PM
Registered User
I'm running my Actro 40-5 on 32 cells at 60 amps fresh off the charger. APC-E 18x10 prop, Actronic 70-32 ESC. Never a hiccup.

Another option if you want to run 30 cells is the Maxcim "Y" wind. Tom's web site probably still says 28 cells, but he now has a controller that supports 30 cells on the "Y" wind. This would be around a 1500 watt system, and it's available now, not some vague distant date. If this interests you, I'd call him or email him with your requirements.


Feb 25, 2003, 05:18 PM
Our Daddy and Heli Junkie
Fred Bronk's Avatar
Remember the numbers are just that, and you won't be at WOT all the time.

6 minutes should be easy with a good BL system, LRK style or not. The effeciency will be very close between the 2 when you add in the loss for the GB and extra wieght.

As for gear noise, what noise?
Feb 26, 2003, 06:35 PM
Registered User
Bill Mixon's Avatar
I've been looking at Motocalc and come up with this.

Hacker B50 11XL, 6.7:1 drive, 22X10 APC, 20 sanyo 2400's

This setup shows a WOT thrust of 215 oz, 40mph PS, at 45 amps, 930 watts.
This looks good, but I wonder how close this will be to what the actual motor does. Also, on everything I ran it said that the Battery temp was too high.

Feb 26, 2003, 07:31 PM
Our Daddy and Heli Junkie
Fred Bronk's Avatar
MC gives you numbers in raw static form. The motor will unload during actual flight and you will have cooling for the batteries.

MC also allows you to do in flight calcs at diff throttle settings.
Feb 26, 2003, 08:47 PM
Product Manager at Hobbico
GWRIGHT's Avatar
the temperature thing in motocalc bugs me lot too. If it were correct, i'd be burning up a battery pack every flight on most everything I fly You can of course turn the temperature numbers off.

APC now has 22X12 and 24X12, so you might want to go a bit larger on the prop and up a wind or two in motor.
Or, just up to the 22X12. Current is usually a touch higher than motocalc predicts, but for 3D flying with lots of throttle usage, 50 amps isn't too much on those motors. Even a bit higher is Ok. Remember, you'll be using throttle a lot, so static current has almost no bearing on flight time. I've even found that some higher static-current setups have given more flight time than lower current setups because they're more efficient in the air, so for a given level of performance, the throttle is much further back, and on average you draw lower current during flight. Motocalc is an invaluable tool, but it isn't the final word, it just serves to get you in the right ballpark. Once you're flying a given setup, and know the performance level, motocalc is great for comparing different paramaters though, like changing props and cellcounts and comparing the performance to what you actually see with a single setup to see if it looks like it will be better or worse, without expending the calories and time to try everything available.
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Feb 27, 2003, 08:30 PM
Registered User
Bill Mixon's Avatar
Thanks for the tips, Gary

One thing that suprised me was the difference between RC 2400 cells and the CP 2400 cells on the same power system. I expected some difference, but not as much as it showed.

I think I'm going to work around the 22 X 10 APC prop. I wonder if APC is going to make any other pitch sizes in this same dia. I've got some concerns about the gyro forces of the 22-24" props, and also the performance of the 10-12" pitch sizes. It seems that pitch sizes lower than 10" have worked the best on other 3D planes. If I remember correctly the 20X8 worked best on the Funtana, and the 14X7 worked well on the E3D. Please correct me if I'm wrong on this.

Feb 27, 2003, 08:48 PM
Recruiter - 60 Amp Club
Ed Lyerly's Avatar
Here's a suggestion for you
Feb 27, 2003, 09:40 PM
Product Manager at Hobbico
GWRIGHT's Avatar
Bill, it's not the actual pitch that's the problem, it's the pitch to diameter ratio. You want to be somewhere between 2 to 1 and 1.5 to 1,..i.e. 12X6 to 12X8, 20X10 to 20X12.6,.. etc etc. the 20X8 on the funtana is actually a bit low in pitch speed, but the right wind motor coupled with the right gear ratio just wasn't found for the 20X10/11/13 props. The current setup on aero-models' funtana (and will be on mine if UPS ever gets it here) is 6.7 ratio on the 14XL with the 22X12 (yes, they have 12 pitch on the 22 inch prop now). Keep in mind we're using 30 cells, though, so you'd need a bit "hotter" motor for lower cellcount. Back to the p/d ratio thing. Unless you're actually flying right at pitch speed (where the entire prop is at the same angle of attack), some portion of the prop is at a very high angle of attack (the root), so as you go down in pitch/dia ratio, more of the prop near the hub is actually working in hover, and not stalled. The downfall is that the prop stops making thrust sooner as speed increases. The higher the p/d ratio, the less prop you have working in hover (the root angle of attack deams that part of the prop stalled and only the very tips are working), but,.. the more thrust you have at higher speeds, since the angle of attack of the entire blade is higher, although now below stall angle of attack since you have pitch. I really think that for 3D type flying, we need some progressive pitch electric props like zinger has with some of their wood props (18X6X10, etc).
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Feb 28, 2003, 09:08 AM
Registered User
Bill Mixon's Avatar
Thanks, Ed

The P/D ratio makes perfect sense.
Progressive pitch props would be great. I wonder what the guys at APC would say if someone told them that they now needed to make the thin E series in various progressive pitch sizes.


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