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Medusa motors

Old 10-01-2008, 05:34 PM
  #1  
celticflyer
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Default Medusa motors

MEDUSA MOTORS, does anyone have any experience with these motors?
I need a replacement for a warp4 to power my MiniMag.

John
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Old 10-01-2008, 07:56 PM
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bajinuk
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i have actually used a medusa 28-32-1200 and warp4 6-turn 1190 to power a minimag and can tell you there is not much difference between the motors apart. I ran them both on 8x4 and 9x4.5 props. The warp 4 actually performed slightly better and is cheaper.

--------------------------V-----A--- rpm-----g-----%
medusa 1800 30C 8x4----11.45--13.2--10290--727--64
------------------9x4.5--11.19--16.2--8850---795--55
warp4 2200 10C 8x4----10.49--14.4--10350--736--65
------2400 30C 9x4.5--11.2---17.8---9060--835--54

Even though the 9x4.5 runs at 55% efficiency i prefer the 9. The longer can medusa 28-40-1200 would be more suitable for the 9 but the shorter can works just fine.

I got my warp4 from http://aircraft-world.com/default.asp .
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Old 10-01-2008, 11:06 PM
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I used a Warp4 6-turn on a MiniMag 32amp Powerup esc and an 1800mah 20c
Prop was GWS8x4.7,8x6 and apc 8x6
My problem is that I kept burning wires off the motor and I just fried a new 32amp esc
I noticed that one of my wires is only held on by 2 strands.
I thought that I'd look for another replacement.
John
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Old 10-02-2008, 12:03 AM
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Dr Kiwi
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As far as I know Medusa are very good - if you need a 28mm motor you can also try Dave's ARC range at www.lightflightrc.com.
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Old 10-02-2008, 03:18 AM
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I just ordered a Turnigy TR28-30b (1050) kv It's an outrunner but I'll get it mounted.

John
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Old 10-04-2008, 05:07 PM
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This response is probably too late for you since you already ordered a motor, but many help other readers...I have a couple of Turnigys, multiple Megas, and a Medusa 28-40-2500 V1 (the new V2's have more vent holes and can take higher current). The Medusa is currently on a Multiplex FunJet direct drive with a 6.5 x 4 Aeronaut prop on 3S1P 2100 mAh lipos. It pulls about 34A in flight shown by a digital recorder with speeds in the high 80 to low 90 mph range.

IME the Medusa is a good as a similar size Mega 16/15/XX in durability and performance, and now with the DM high against the USD, the Medusas are a better buy. It does have a little softer shaft so it will bend rather than snap like the Mega will, and it can be straightened if you are careful. I generally snap a Mega shaft if I try to straighten it.

The 2500 Kv Medusa splits the difference between the 2000 Kv Mega 16/15/4 and the 3000 Kv 16/15/3 and after trying the Megas it is the sweet spot for me in the FunJet. I have not had to return the Medusa for service but I have snapped Mega shafts and had to wait 4 weeks turn around plus the $30 for the repair (they don't sell the shafts for DIY repairs I think they just replace the entire rotor)

The Turnigys are not in the same class as the Mega or Medusa, but they are 1/3 the price too. The machining and finishing are about the same, but their quality of magnets and steel is not on a par with the other two. I have several in different sizes on different planes and while they are serviceable they are clearly not as good. However, for the price they are hard to beat.

If you want to go cheap, can deal with an outrunner vs. an inrunner, and can suffer with a little less flight time due to less motor efficiency, then they and the KD brand also sold by Hobby City (AKA Hobby King) are about the best cheap motors going. However.....they have very soft shafts so buy extras when you order the motor. They are easy to replace if you have a very small Allen wrench and a press (a drill press works great) and can be straighten very easily with a little patient work. The shafts are so cheap I generally don't bother and just throw them out.

Working at less efficiency, the cheaper motors will produce more waste heat than a quality motor so you have to be sure they get enough cooling air - more than the quality motor could live with. Treated right they will do the job.

FC
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Old 10-04-2008, 07:30 PM
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FC, thanx for your input. I have altered th MM to get a lot more air over the motor.
This is a setup to train my grandsons. My main flyer is a STIFFY powered with a 480.
WHAT A RIDE

John
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Old 10-24-2008, 11:23 PM
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This is just what I've been looking for. I have a new MiniMag and am wanting to start out with a brushless motor so that as I progress I can convert over to the float option and fly off the lake in my back yard.

I currently have a Park 480 BL, 45 amp ESC, and a Tenergy 25C 2400mAh 11.1V 3S LiPo. My feeling is that the ESC and batt. are too heavy for this plane (I am new to electrics and started out with a Taylorcraft, but it is too much plane for me right now.) I went with the MiniMag because the fuse and wing are relatively cheap for replacement parts.

My goal is to get a few parts that will be usable on a variety of aircraft in this size range. For this reason I purchased the MiniMag Kit which only came with the motor. I would have eliminated that if I could have but couldn't find a version of the kit that did not have it.

So, I am looking for a brushless motor that will be a 'drop in' with the MiniMag if possible, but I also like the Turnigy and KD motors mentioned above, especially because of the lower price. I would much rather replace a couple cheap motors vs. a couple more expensive ones.

My only concern with the Turnigy/KD route is modifying the motor mount area in the foamy.

I would appreciate any comments/suggestions.

Thanks, Dave
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Old 10-25-2008, 12:55 AM
  #9  
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"My only concern with the Turnigy/KD route is modifying the motor mount area in the foamy."

The problem with altering the motor mount is getting the correct angle, and where to put it. If you can find an inrunner with holes the same distance it will make the job easier. You need a KV of about 1100 to 1500 and about 200 to 300 watts.
I had a warp4 turn 6 and it was great. I eventually burned it up as I didn't have proper ventilation. Rasp out an area under the motor and on the cover create an air scoop. I'll try to send pictures later.
John
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Old 10-25-2008, 01:34 AM
  #10  
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I used a Turnigy With a GWS9/4.7 SF I get 172 watts and draw about 14.5 amps It flys great with an APC 10/3.8 sf but the amp draw is a little high.

John
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Old 10-27-2008, 12:19 AM
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Hi John,

Thanks for your speedy reply. I think I may have found a solution on the motor. I fully agree that I would much rather not mess with tryinig to install a different motor mount/firewall with all of those complications.

I discovered that the Warp4 is no longer in production. However, I did find, at HobbyKing.com, some KDA inrunner BL motors in the 28mm range. They range from 1800 to 2600 kv, and from 16a to 27a. The specs did not mention the wattage and I'm useless in the electronics field and don't know how to figure that.

These motors are prewired with the goldplated connectors. From the pictures they look very much like the Multiplex Permax 400 that came with the kit.

The other plus is that these motors are priced under $30, which is much more attractive than $65-75 per. Do you think these are compatible. Tomorrow I plan on talking with Hobby King to get their take also.

The remaining questions are, 1. If this motor works can I use my 45 amp BL ESC with this motor, and 2. What LiPo would work with this set up?

Thanks again, Dave
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Old 10-27-2008, 01:42 AM
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There just isn't enough information at Hobbyking. You need about 16mm between mounting holes. It is possible to mount an outrunner by using the shaft end but the mounting holes and the wire routing is important. I think that a higher kv might be a problem, but then I don't have any experience in that area.
I prefer 1000 to 1500 kv 1200 with a prop that produces over 200 watts. For reasonable motors you might check with HEADSUP. Call Jeff on the phone and he might help. If I were doing it again I'd use a Himax HB2815-1400, a little costly but a drop-in that should give great performance.
John
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Old 10-27-2008, 01:44 AM
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http://www.headsuprc.com/servlet/StoreFront
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Old 10-27-2008, 04:02 AM
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We just released a 28mm inrunner with 2000kv for under $50 retail.

Check it out.

Joe
Common Sense RC
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Old 10-27-2008, 06:24 AM
  #15  
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Originally Posted by Joe_Curd View Post
We just released a 28mm inrunner with 2000kv for under $50 retail.

Check it out.

Joe
Common Sense RC
Joe, who is we? Do you have a website?
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Old 10-27-2008, 05:08 PM
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Celtic,

Our website is www.CommonSenseRC.com

Thanks,
Joe
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Old 10-27-2008, 06:07 PM
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Hi John

Thanks again for your suggestions. I've sent an email to Headsuprc and will see what they have to say. I haven't called Hobby King yet to see what they have to say.

Can you say a bit more about your comment: "with a prop that produces over 200 watts?" How do you determine how much wattage is produced?

Also, I am still stymied as to how to determine the amps for the ESC, and which type of LiPo to select (it looks like it should be 7.4v or 11.1v - but how do you determine this?). Also, how do you determine the level of the "mAh" for a LiPo?

Dave
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Old 10-30-2008, 06:09 AM
  #18  
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The 10/3.8 APC produces a lot of power but the amp draw is high at full throttle.
GWS 9/4.7 produces 172 watts (good power) and amp draw is within reason.

You always start at the motor. The manufacturer should give you MAX amp draw. Always buy an esc that is say 10% higher then choose a prop that achives the best power without going over max amps by more than a small amount at full throttle.

7.4 lipos are ok for small or lightweight planes and large props for indoor flying but they are not enough power for good performance i.e. aerobatics or 3D. For that you need a 3 cell 11.1 (planes 2 lb. and under)
Discharge rate or (C) is also important. Low c is ok for servos on larger planes but a powerful motor need to draw a lot more. My MiniMag @ 22 0z. fly wt. for example; I use a motor that will produce about 32 0z. of thrust Max draw 14 continuas amps and bursts of 18 amps My ESC is a POWERUP 32 amp and my batteries are 1800 mah @ 20c
Headsup has a lot of information at his site about power setups but one thing that you really need is a watt meter.
I'm sure that someone else will weigh in on this as there are many more criteria and ideas that work for others. I'll try and find some websites that give planes and setups that work well at a reasonable cost.

John
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Old 10-30-2008, 06:12 AM
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Try this site. I fly this LAZER and it is a ball. I use his 900mah 20c batteries. The price is not bad.
http://www.ncweb.com/biz/dan/
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Old 10-30-2008, 05:49 PM
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Originally Posted by ddraggoo View Post
Hi John

Thanks again for your suggestions. I've sent an email to Headsuprc and will see what they have to say. I haven't called Hobby King yet to see what they have to say.

Can you say a bit more about your comment: "with a prop that produces over 200 watts?" How do you determine how much wattage is produced?

Also, I am still stymied as to how to determine the amps for the ESC, and which type of LiPo to select (it looks like it should be 7.4v or 11.1v - but how do you determine this?). Also, how do you determine the level of the "mAh" for a LiPo?

Dave
Please - neither motors nor props produce power/watts - they consume it, or cause it to be consumed. [my pedantic rant is now over!].

The amp draw (and thus watts or "power") is determined by the characteristics of the motor (particularly Kv) in concert with the voltage applied and the size of the prop. All motors have amp/watts limits and so choice of prop with regard to Kv and voltage applied is critical. Increase voltage or Kv and you'll need a smaller prop to keep the system within its limits.

ESC rating - the ESC needs to be able to cope with the maximum a motor can handle, plus a bit more for safety - thus if your motor is going to draw 20A max, then use say a 25A ESC.

Voltage: this depends on Kv and the size of the prop you want to use. For any one motor, you can spin a big prop on 2s or a smaller prop on 3s and keep amp draw and watts-in within limits. For the same amount of power-in, you can have low voltage/higher amps, or higher voltage/lower amps - it just depends on your chosen application. For 3D you usually want a large, low pitch prop spun slowly.... for pylon racing you'd want a small, high pitched prop, spun fast. If you choose a motor with high Kv, and yet you want a big prop... you may NOT be able to run it on 3s. Choose a lower Kv motor and you will be able to use 2s or 3s with that big prop.

mAh: Lipo packs are rated using a C rating - a 20C 1500mAh Lipo is said to be good for 20x1.5 = 30A draw. The actual size of the pack (mAh) is your fuel tank - more mAh gets you longer flight time. The 30A from a 1500mAh pack gets you 3 minutes at WOT (actually it'll be a bit less since you can't suck every last drop out of your "tank". Put a 20C 3000mAh pack in there and you get 6 minutes. If you don't hold the throttle at WOT and only average 15A draw, you'll get 12 minutes... and so on. Weight can be a determining factor in choosing a pack.

Hope this helps,

Cheers, Phil
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Old 10-31-2008, 05:18 AM
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Please - neither motors nor props produce power/watts - they consume it, or cause it to be consumed. [my pedantic rant is now over!]. (DR KIWI)

Never suggested that they didn't consume it,just that the wrong prop could over work the motor. That is highly unlikely with a 2cell but 3cell needs more caution.
I still start at the motor. I buy one that will do the job on the plane I intend to fly. Next I match an ESC to the limits of the motor. Battery capable of providing power that I will require and a prop to give best performance without frying my motor.
Personally, I couldn't get along without a watt meter.
Now if you suck the full 30amps all the time or 20 for that matter, your flight times will be short. The 1800mah 20c will fly my 22oz. MiniMag for 10 minutes wide open and still leave me over 10 amps left. I have flown this setup, conservatively, for over 20 min.
John
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Old 10-31-2008, 05:25 AM
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PS DR KIWI, for dddraggoo sake, I agree with your input. ddraggoo needs to understand KV (rpm per volt) That is why most of us use 3 cells or more. But of course a 4 oz. plane for indoor flying doesn't need to be weighted down with all that big of battery.
John
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Old 10-31-2008, 02:15 PM
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Thanks Fellas, your input is most helpful and very much appreciated. One of the reasons for that one question is that the phrase in celticflyer's response above reading: "with a prop that produces over 200 watts?" was a little confusing, because with the little that I do know I felt that a prop would 'draw' energy vs. producing it. Beyond that, all of your input is helping to answer a lot of questions for me. Now I'm just struggling with wading thru all of the forums and all of the websites trying to find the best motor/esc/batt option. All in due time!

Dave
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Old 10-31-2008, 03:20 PM
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I usually start with the prop. Decide on how much thrust you need at what speed... choose a prop which can get you what you need - choose a motor which can spin that prop at that speed using a bit less than its max power rating - choose an ESC big enough for the job - choose a pack which can supply that amount of power.
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Old 10-31-2008, 03:59 PM
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Dave,

Unfortunately, a dirt cheap low Kv inrunner is hard to come by; trust me, i have a spent a long time looking. Your best bet would be a 2nd hand motor on ebay.

You can still buy warp4 6-turn at http://aircraft-world.com/default.asp ($50) and if you bend the shaft you can have the motor replaced at 40% discount. I bent my shaft and asked them if they could replace the armature; they told me they couldnt but offered me a replacement motor discounted 40%. Stick to 8x4apc e to keep within the motors specs and you shouldnt have any problems regarding heat and motor wires burning out. With this setup shell also take off from water easily.

Nicholas
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