Inrunner vs. Outrunner data (was in "New Hacker outrunner motor" thread) - RC Groups
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Jun 24, 2004, 04:50 PM

Outrunner or Inside Runner ?

Recently some questions in regards to the different power options for the Venus 40 ARF were discussed. I Decided to do some testing with the AXI 4120-18 on my Venus 40 arf. I also tested the typical Hacker B50 with Planetary Gearbox.

My Goal is not to find a winner, but more importantly to better understand some of the choices available to us. Here are the results as I measured them on a typical Phoenix day, at a typical flying Field, in a typical model that many are familiar with.

What is efficiency of the motor, ESC or the battery? Does it really matter ??

I am really only interested in how many amps, at what voltage, it takes to make a given prop turn, a given RPM , sufficient to fly my model the way I like to fly...and have Fun, that is what this is really all about.

Here's my little experiment.

Venus 40 ARF Ready to fly, AUW= 93oz. or 5.81 lbs
AXI 4120/18 Motor weight=11.3oz
Hacker Master 70-O-Flight ESC weight= 1.35oz.
Thunder Power 5s3p weight= 22oz

following pics of model and Axi installed using the Hacker master controller
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Jun 24, 2004, 04:53 PM


Before flying I used the new Hacker master controller and PROG-Box, to set-up the AXI 4120/18
Jun 24, 2004, 04:56 PM

AXI 4120/18 with APC-E 15x10 Prop results

Static testing revealed some good data as follows:

Ambient Temperature 83 F.

15x10 APC-E Prop
Timing advance is set to 24 degrees

Full throttle= 58.7 amps, 980 watts, 16.5 volts
Prop RPM=7000

These figures are a little high according to Hobby Lobby, A 15x8 prop will now be tested.
Jun 24, 2004, 04:58 PM

AXI 4120/18 with APC-E 15x8 Prop

Installed the 15x8 APC-E Prop static results as follows:

Ambient Temperature 90 F.

15x8 APC-E Prop
Timing advance is set to 24 degrees

Full throttle= 52.3 amps, 905 watts, 17.2 volts
Prop RPM=7300

The model flew very well with this set-up, the full throttle vertical climb was unlimited (Slow). The part throttle cruising required about 3/4 stick, but the speed was enough to easy loops from level flight. Full throttle was pretty good in level flight , but not the same as a glow .46.

Prop "Noise" was clearly audible, but less than the gearbox systems. Please keep in mind I fly at a "Glow" club, and Prop sound feedback can very usefull to determine the status of the system.....

The motor temp following a 10 min flight was 140F, the controller was 125F and the batteries were 120F.

I decided to test the part throttle static current as follows:
Using the identical throttle position as during the flight, at the lowest comfortable "cruise" setting about +3/4 stick.

The following measurements were made:

Part throttle Current 43.5amps @ 6900 RPM.
Jun 24, 2004, 05:10 PM

Hacker B50 13S+6.7 in the Venus

Switched the AXI out for the Hacker system

Venus 40 ARF Ready to fly, AUW= 90.7oz. or 5.60 lbs
Hacker B50 13S+6.7:1 Motor weight=9 oz
Hacker Master 70-O-Flight ESC weight= 1.35oz.
Thunder Power 5s3p weight= 22oz
Jun 24, 2004, 05:15 PM

Hacker B50 13S+6.7:1 set-up

set-up the B50 13S using the PROG-Box setting the timing for 3 degrees advance. set the controller for 5s Lipo and 3.0 Volt cut-off. Motor rotation was set for Left rotation.
Jun 24, 2004, 05:20 PM

Hacker B50 13S+6.7:1 with APC-E 15x10 prop

The static and flight tests were performed using the 15x10 APC-E prop.
Results as follows:

ambient Temp 83 degrees
Full throttle 45.7amps
Prop RPM 7000
776 watts

The model flew very well with this set-up, still not the speed as a Glow .46, but very good unlimited vertical (medium speed) and good overall aerobatic power. Flight times are typically 20 min with this set-up. Throttle position at cruise was about 1/2 stick, capable of easy loops and rolls at this setting.

Following a 10 min flight motor temp was 130, batt was 110, and ESC 100 degrees.
Jun 24, 2004, 05:23 PM

Hacker B50 13S with 15x10 Prop Part throttle

The Throttle position during the flight was noted and a fresh pack was used to document the "Cruise" throttle static current as follows:

Cruise throttle 35.6 Amps
Cruise throttle RPM 6600
Jun 24, 2004, 05:34 PM

outrunner and inside runner data

Simple results:

AXI 4120/18 + 15x10 Prop = 7000rpm@58.7amps

Hacker B50 13S/6.7 + 15x10 Prop = 7000rpm@45.7amps

What can we learn from this , different motors can work differently. No question the Outrunner will work very well to this type of model. Is the Inside runner Losing lots of power through the gearbox, does not apper so.

I believe each motor has its, place and $$ Price. I have learned there is no "Free lunch" and in the case of these examples, this rings true.

The AXI is lower Price, and heavier, more current for this model.
The Hacker higher price, lighter, less current for this model.

I hope this doesn't start negative debate , but rather constructive discussions about how different power systems can affect the performance of our models.

Jun 24, 2004, 05:39 PM
Registered User
Bill Mixon's Avatar
Thanks for taking the time to post all that data, Sean.

A bit off topic but..
Can you use that prog box on the new Jeti Advance control or will it only work with the new Hacker esc's?
Looks like it makes things a whole lot easier to set up.

Jun 24, 2004, 05:46 PM
310mph Kolibri T25 Swist
henke's Avatar
finally some useful info! thanks Sean!
Jun 24, 2004, 06:14 PM
Registered User
davidfee's Avatar
Anyone notice the extreme difference in timing advance between the two tests? 24 deg vs 3 deg. Granted, there are differences in the timing requirements of in-runners and out-runners. However, advancing the timing generally results in slightly higher rpm but at the expense of efficiency.

Sean, not questioning your results or conclusions but, it would be useful to see results with less advance on the AXI.

(I don't even have any out-runners, so I have no motive other than curiosity)
Last edited by davidfee; Jun 24, 2004 at 06:17 PM.
Jun 24, 2004, 06:24 PM
310mph Kolibri T25 Swist
henke's Avatar
good idea, would be intheresting to see what effects diffrent timing has on booth Hacker and AXI...
Jun 24, 2004, 07:12 PM
Understand the question,

The timing selected I consider to be "Neutral" for each motor.

When I go lower than 24 degrees, on the AXI the power drops (Prop RPM decrease), and the start-up begins to hesitate, I can go all the way to 30 degrees on the Axi, but things don't look so good in the Amps department (Higher than recommended)

On the Hacker the 0 degree timing does reduce current, and the power drops a little, but mostly the system feels sluggish when throttle is quickly increased. I can go to 7 degrees and the amps increase, but with only small increases in prop RPM, (Not as efficient as 3 degrees)

The nice thing about the new Hacker Master Controller /Prog Box is these exact adjustments can be quickly and easily changed at the Field. Really fun stuff to play around with...

Jun 24, 2004, 07:14 PM
Hi Bill,

The PROG-Box only works on the NEW Hacker Master ESC's


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