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View Full Version : AXI 5330/18 versus 5320/28


Tweet
08-10-2005, 03:43 AM
Both these motors are specified at 249 RPM per volt. The 5330/18 weighs 6.5 ounces more and is larger. The 5330/18 also has a lower specified resistance (.032 ohms versus .057 ohms). When I run them both through Motocalc using the same prop and number of cells the produces substantially more thrust (and draws more current). Does anyone know why?

rcers
08-10-2005, 02:51 PM
Motocalc is notoriusly bad at outrunners. I finally gave up on it and just use the wattmeter. I know that doesn't help much in the purchase decision, so I use others expierences for real life input on what to buy, then fine tune with the meter.

Mike

Tweet
08-10-2005, 03:54 PM
Thanks, Mike. But is their any other reason (besides Motocalc errors) that the two motors with the same RPM/V would produce substantially different results with the same voltage in?

rcers
08-10-2005, 03:56 PM
The can lenght must have something to do with their logic. That is valid, to a degree...

Mike

Greg Covey
08-10-2005, 05:04 PM
Tweet,

These are two different motors that just happen to have similar Kv or RPM/v ratings. Comparing the two are apples and oranges.

The first two numbers of an AXI motor are the diameter, the last two are the rotor length. Both dimensions increase power with increased size. Note that the we have a 20mm and 30mm rotor length which makes the latter one more powerful.

Although Motocalc can be accurate at times, use it only as a starting block.

Regards.

Tweet
08-11-2005, 02:58 AM
Greg, that makes perfect sense. Thanks.

Matt Kirsch
08-11-2005, 05:26 PM
Tweet,

Back to why you got different numbers... It depends on how much battery and prop you were putting to the two motors.

In a nutshell, the 5330 can handle more power because it's a physically larger motor, but with similar Kv ratings, the two should perform similarly to a point. That point is where the efficiency curve on the 5320 peaks and starts back down the steep backside. At that point, you're pushing the 5320 beyond its limits, while the 5330 is still yelling, "BRING ON THE PAIN!"

Tweet
08-11-2005, 10:00 PM
Matt,

Understand. This is where the min/max efficiency current specification come in. On 8S with the 5330 at the minimum efficient current my H9 Funtana 90 I have almost a 1:1 thrust to weight ratio according to motocalc, so (and this makes sense) the 5320 would be a better match for that weight airplane.

Matt Kirsch
08-16-2005, 03:41 AM
Bingo. Always use the lightest motor that will handle the power needed for the airplane when all other things are equal.

DickCorby
10-06-2005, 07:02 AM
I make my AXI motor choices pretty much based on the specifications for the weight of model they can fly. So far this has worked out pretty good for me.

I'm in the process of taking my 7.5 Lb Corby Starlet from the 4120/14 swinging a 15E prop to a 4130/16 swinging a 17 inch E prop. This also allows me to go from a 4S-2P pack to a 5S-2P pack. Overall this should be a big increase in performance.

The plane flew great with the 4120, but did lack some performance and to get level flight was closer to 3/4 throttle. I expect also to be able to get it to fly closer to half throttle and give longer flight times with the bigger motor.

I have a Yak coming that will be in the 4-5 Lb range RTF, and the 4120 should be great for it. 2 Lbs of weight can make a big difference in what motor you choose.

jrb
10-06-2005, 06:12 PM
I ran the numbers in my Calc spreadsheet and got results within 5% of each other; very good agreement.

Have had a lot of success with my Calc and it has always had good agrgreement with the others.

What I find as being “notoriously bad” is that the motor manufacturers provide bad data/parameters – “garbage in/garbage out”!

For example, they often don’t give you Kv! But rather rpm/volts; they don’t do the extra work and give us the results of dividing rpm by the applied volts – ignoring the voltage dropped across Rm based on Io – there is a difference.


Definition “Tweet” = a device that is efficient at turning JP-4 into noise!

DickCorby
10-06-2005, 06:49 PM
You can go to the AXI motor website and get more information than you want. KISS principal says "if the weight of your plane is in the range shown for a motor in their listing, it will fly"

For aerobatic of course you want to stay in the lower half of the weight range.

DickCorby
10-06-2005, 07:01 PM
Tweet,

These are two different motors that just happen to have similar Kv or RPM/v ratings. Comparing the two are apples and oranges.

The first two numbers of an AXI motor are the diameter, the last two are the rotor length. Both dimensions increase power with increased size. Note that the we have a 20mm and 30mm rotor length which makes the latter one more powerful.

Although Motocalc can be accurate at times, use it only as a starting block.

Regards.

Dont you also have to figure in the last 2 numbers? (behind the /) I believe that is the winding count, which if yoou are going to get real technical must also be considered in the overall equation.

Which is why I avoid the Technical stuff. (had enough of that in 30 years of working on computers)

Tweet
10-06-2005, 09:08 PM
Definition “Tweet” = a device that is efficient at turning JP-4 into noise!

You got that right, but it wasn't so bad from the cockpit.

jrb
10-06-2005, 09:11 PM
Not while on the flight line with canopy open!

Tweet
10-06-2005, 09:40 PM
Not while on the flight line with canopy open!

That is what the brain bucket was for. Did you go through USAF UPT JRB? I did and then stayed on as a Tweet IP for three years before going on to the "real" AF. Enjoyed my time as an IP though.

DickCorby
10-06-2005, 09:48 PM
That is what the brain bucket was for. Did you go through USAF UPT JRB? I did and then stayed on as a Tweet IP for three years before going on to the "real" AF. Enjoyed my time as an IP though.

The "Real" AF??? You were in the brown shoe Navy?? I spent 20 years in the Naval Weather Service, briefing Naval pilots. Now thats a pilot for you - able to land on a postage stamp in the middle of the ocean, and do it almost every time.

jrb
10-06-2005, 09:49 PM
Been meaning to post that for sometime; over yonder actually.

Retired Reserve; in my whole time in the AF I was told I wasn’t in the “real AF”: ATC, SAC, ALC/Systems Command, & USAFR.

Most of my time was in the Engineering world where I did propulsion tests and systems; rocket & airbreathing.

But, my Tweet experience unfortunately, was just a couple of rides.

Tweet
10-06-2005, 09:58 PM
The "Real" AF??? You were in the brown shoe Navy?? I spent 20 years in the Naval Weather Service, briefing Naval pilots. Now thats a pilot for you - able to land on a postage stamp in the middle of the ocean, and do it almost every time.

Ha ha. I came close to going Navy. I was AF enlisted, finished my degree and talked to the Navy.

I do feel a carrier landing in rough seas with low visibility has to be the ultimate aviation challenge. However, the monsoon season in Korea (my assignment post Tweet) provided some interesting moments.

FAIRCHILD 24
10-24-2006, 04:47 PM
You got that right, but it wasn't so bad from the cockpit.
Hi Tweet,
You wouldn't have any 8.5"x11" dwgs os the tweet, in 3 view format would you?
I am a mechanical designer drafter withmy own 3D parametric CAD package on my computer. If you can come up with those, I can come up with any size model you want on paper.
I like the tweets looks and would love to make a flying model of one.
I am an Instructor Pilot, Civilian style, rated in 1977.
My first plane I owned was a Fairchild 24 hence my handle.
Mine was a special F24. It was converted from a 145 HP Warner,
to a 220 HPContinental engine. She wasn't fast but she climed like a freight elevator.!
On one flight I remember on board we had (2) 210lb people and (2) 180 lb. people.
55 gallons of gas and 5 gallons of oil. On takeoff We broke ground in a short distance and climbed away at over 1,400 ft./min.
Not a tweet but fun.
I started flying in 1960 and flying models in Korat Thailand in 1966.
I watched in wonder one day as a Thai. Arforce pilot landed gear up and slid to a stop. Next thing I see is a huge peice of equipment driving out to it. They picked it up, dropped the gear, placed it back on the runway. The next thig I see is it taxing away like nothing ever happened! Amazing.
As far as designing goes I have designed 10 from scratch. ALL FLEW.
Hope you have some dwgs. Hope to hear from you soon.
Ray Henry try-plan-b@tampabay.rr.com

FAIRCHILD 24
10-24-2006, 04:50 PM
This Spell Check Sucks!

Magoo
12-29-2006, 08:25 PM
I have been using AXI almost exclusively for the last two-three years. I currently run a H9 Showtime 90 with a AXI 4130.

I got a H9 Funtana X 100 ARF (http://www.horizonhobby.com/Products/Default.aspx?ProdID=HAN4175) for Christmas and going to put an EFlite 110 in it. Is there anyone with Eflite motor experience out there?


http://www.flyinggiants.com/forums/images/temp/plane.gif

Thanks,

Larry

jooNorway
12-30-2006, 02:22 PM
The 5330 is appr 30% "stronger" than the 5320.

The additional number which tells the number of windings at each stator-arm tell you what kind of plane it suits. A patternplane requires a higher RPM at a propeller with quite high pitch. Then few winding is what suits. A 3D-plane run a large diameter propell with low pitch at lower RPM, and more windings, thinner wire and maybe higher voltage gives the thrust from low RPM.

The kV-number is worth a study. We want appr 9-10.000 RPM for a patternplane, and 5-7000 RPM for the 3D-birds. But the kV-numbers are given for an unloaded motor. Usually the RPM will be appr 25-30% lower in practice.

http://www.modelmotors.cz/index.php?page=1 is the homepage for AXI.

Jollyroger
12-31-2006, 04:19 PM
Has anybody seen the Axi tandem motor setup? looks like it should pull a DC 3.:D. How about a giant scale warbird? Or maybe a P-61 ginat scale?
The batts would break yer wallet and cause much discomfort from SWMBO.
I like Axis, I wish they were more efficient, though it doesn't matter too much
for sport flying.

feathermerchant
01-03-2007, 02:58 AM
So has anyone run both on similar packs and same prop?
I'd like to know.
Here's a datapoint.
AXI 5330/18 8S Tanic 4,350 Phx 45HV APCE 20X10 1,700W
Pulls a 14.5lb biplane (GP Hawk P6) almost vertical.
not even warm on landing.

I'd like to try the 5320 to drop some weight.

Matt Kirsch
01-03-2007, 07:15 PM
A 20x10 on 8S with a 45HV? I'll have to take that into consideration. I've got a 5330/18 on a Kangke Waco biplane. What little flying I've done is on a 10S with a 16x10 prop. It seems like I have to run at way too high of a throttle setting to keep the plane flying level, and I am suspecting that an excess of pitch speed and a lack of thrust is what ails me with this big, draggy bipe.

I chose the 5330 over the 5320 in this case for weight. The extra two ounces hung way out in front was all it took to balance the plane. Sure beat having to figure out a way to hang the batteries up in the cowl.

Here's a data point on the 5320: Running a 16x10 APC Thin-E on 10S 3300mAh Polyquests, draw was around 35A. This is on a Giant UCanDo3D, and is plenty for smooth aerobatics.

Another data point: Running a 19x11 or a 20x10 and 10S Kokam 3200s. Don't remember exactly how hot it was, but Amp draw was absolutely ungodly. Way too much prop unless you're trying to use the motor as a space heater.

I'm thinking a 17x10 or 18x8 will be a good match to get the 5320 to draw around 50 Amps.

feathermerchant
01-07-2007, 04:23 AM
A 5330 weighs 23oz and a 5320 17.5oz so the difference is 5.5oz. Anyway the 5330 and 20X10 haul my biplane around great on 8S.

Louis4sun
01-07-2007, 07:06 PM
A 5330 weighs 23oz and a 5320 17.5oz so the difference is 5.5oz. Anyway the 5330 and 20X10 haul my biplane around great on 8S.
Hi guys

There is an AXI calculator (freeware) here
http://electrofly.free.fr
The site is in french, but the freeware is in english.
Search top icon "telechargements" then "moteurs"
then download MM_Calc v200
then unzip it to get a stand alone .exe (VB)

You can see that the 5320 is very overloaded at 2kW when 5330 is able at the limit.
Of course this type of software depends of the validity of parameters in the embedded data base.

But it is better than nothing.
Louis