Mega 16/15/2 w/Alfafan EDF

[Bmiller]

Greetings,
I have this on the way and was just told about the possibility that the
megas 6 pole motor max rpm MAY be only 50,000rpm due to the switching capability required of the ESC.
For example, a 2 pole Hacker motor won't hit the limit until 150K.
I'll be using a CC phoenix45A.
This is cause for concern as I was planning on using 4 or 5S to spin the fan at 64,000+rpm to get the thrust I want.(24+ozs) I've already spun the alfa this high before using a himax 2025/5300 on 4S.:D
Heres my vid on it.http://aeneas.ps.uci.edu/edf/a10gws/f-86-alfa-bruce.wmv
It was dopplered at 102mph.:eek: :D
So I'm not concerned about the fan exploding, it won't.
Anybody have some input/experience with the switching poles and clockspeeds phenomenom (or something like that):confused:

Regards, Bruce

[Rugar]

I've already spun the alfa this high before using a himax 2025/5300 on 4S.:D
Heres my vid on it.http://aeneas.ps.uci.edu/edf/a10gws/f-86-alfa-bruce.wmv
It was dopplered at 102mph.:eek: :D



Very cool! :D

[roccobro]

Bruce-You crazy, cray man. I don't personally think you'll have a problem just from my CD motor experience. The P-10 has a lower rate than the P-45 and I was spinning 55k with a 9 tooth 6 mag motor with one.

We'll see though ;)

[watt_the?!]

oh you da man Bruce!

wish i could help ya...

[Bmiller]

:D Thanks guys!:D
Hope you liked the "Alfa screaming"!
I talked to my friend Herb(resident hipower EDF guy!) at the field today and he thought it'll go to 66,000rpm w/o too much problem so I'll cross my fingers!:rolleyes:
Bruce

[Rugar]

:D Thanks guys!:D
Hope you liked the "Alfa screaming"!
I talked to my friend Herb(resident hipower EDF guy!) at the field today and he thought it'll go to 66,000rpm w/o too much problem so I'll cross my fingers!:rolleyes:
Bruce

Maybe wear a "Flap Jacket" just in case :D.

[watt_the?!]

actually myself and my mate did a stress/strain analysis on this and many other fans...elastic deformation occurs to some extend from the get go...but we figured a value of 90,000rpm before plastic failure. the problem was creep at the hub leading to slip which tends to limit the entire thing...plus fouling of the blades on the inside of the shroud.

Tim.

[watt_the?!]

oh no...this post is to take my total past 666...dont want to be on that number for too long.

[ParkJetsFlyer]

Originally Posted by Bmiller images/images_pb/misc/backlink.gif (http://www.wattflyer.com/forums/showthread.php?t=3072#post29616)
I've already spun the alfa this high before using a himax 2025/5300 on 4S.:D
Heres my vid on it.http://aeneas.ps.uci.edu/edf/a10gws/f-86-alfa-bruce.wmv
It was dopplered at 102mph.:eek: :D

Lordy What a screamer!!!!

[Bmiller]

Well I meant the mega should go 66,000 without a timing problem!;)
I modded a 2mm collet style prop adapter for the rotor as the stock "glue it on" adapter is a hit or miss on centering the rotor.(ie total crap!;)) No slipping here!
At these hi rpms the rotor blades start clearancing themselves on the shroud! gap was less than 1mm new now its at 2mm and doesn't rub anymore!
I ran a thrust test on a new unit w/ 4S 2025/5300
64,000rpm
24oz thrust!
33amps(8A over max rating of 25A)
AUW is 21ozs
Motor in the video lasted 5.95 flights!LOL Good thing these alfas glide well!

[watt_the?!]

i love it...those alfa fans rock!

[Bmiller]

Bruce-You crazy, cray man. I don't personally think you'll have a problem just from my CD motor experience. The P-10 has a lower rate than the P-45 and I was spinning 55k with a 9 tooth 6 mag motor with one.

We'll see though ;)
Thanks Justin,:)
I feel pretty hopeful because of all the testing you did including spinning a mega 16/7/3 to 64,000+rpm with no problems.:cool: Looked at the mega site and all the ACn16 series motors are 6 pole.(kevlar wrapped magnets too)
Thanks again man!
Bruce

[roccobro]

Sweet. I'm still trying to finish up the "other" rotors so we can get a sub sonic rpm thrust maker. :D

Justin

[tashley]

Sounds sweet Bruce.

[Bmiller]

Thanks Tom:) Wish I got video on the last 4S flight w/new impulse2100 pack as it had almost unlimited verticle! (24ozthrust/21oz AUW)
On another note:
I discussed my rotor rubbing problem w/Herb and he immediately said they never stretch that much and more than likely the stators were flexing as the rubbing occurred only on 1/2 of the shroud. I tend to agree with him as he's usually never wrong when it comes to EDF! So now I've CA'd the stators to shroud joint and the outside mounting ring and the unit is 10times stiffer! Next up is a new rotor. I did a 3S amp test with the old 2mmgap rotor and it only drew 16amps! so it's outta there!;)
Bruce

[watt_the?!]

ok no probs about the stretching.

why would i post rubbish here?..

without test, just input the material properties into your model, calculate load at the blade and at the hub, and you WILL show elongation.

heck even steel elongates under load.

what we did observe was slipping of rotors at high rpm in many fans that use a hub clamping attachment. We had 5s on a himax 2025-4200 on the himax.

[Bmiller]

Rubbish? You have not posted any rubbish here. Your comments have been informative and helpful!
I was just saying that it shouldn't have stretched SO much as to rub more than 1mm off the rotors, and only rub 1/2 of the shroud when I had it perfectly centered to start with. If the rubbing was just from stretching, the shroud should have rub marks all the way around. And I agree with your slipping analysis, the stock rotor is only held in place by a little phillipshead screw. My modded prop adapter clamps the rotor between 2 nuts which are torqued down very tightly. It showed no signs of slipping.:)
Regards,
Bruce

[watt_the?!]

yeah youre right..im a bit sensitive after many years at that ''other'' site...

it should be all the way round...and we were surprised also when it (slip)happened..we even showed a small bump in the thrust curve at high rpm that could only be attributed to tip clearance.

we also had a guy who had the alfa fan doing 58000 rpm..and power etc was fine...then he reported even higher rpm for less current..classic symptoms of slip at the hub after cavitation was eliminated.

yours sounds slip free, as the current you're drawing is also spot on.

thanks mate.

Tim.

[Bmiller]

:)

[Bmiller]

YES!:D
My Mega16/15/2 and Alfa Mk2 EDF unit arrived today!
Much thanks to Randy at www.dynamoelectrics.com (http://www.dynamoelectrics.com) for selling me one!
Preliminary investigation reveals alittle too tight of a fit for the mega. Have to remove all stickers from the can and sand the motortube abit.
Also theres a 1-1.5mm lip at the bottom so I'll have to use a spacerplate. (no big deal) Got the teststand all setup so I'll get to work making the motor fit!
Bruce

[roccobro]

Yeehaw! :D

Justin

[tashley]

Rock on B!;)

[Bmiller]

Greetings!
I also received a Justin(Roccobro) modified stock (3.2mm I think?) adapter w/dual setscrews:D Nice work Justin! It's also alot easier to use it rather than modding a prop adapter.
Tim, about the slipping rotors you spoke of, any fixes for it? I want to be able to swap rotors out later so any fixes can't be permanent.:)

Oh and the big news...:(
To create the mega motor fan, ALFA machines the regular fan unit motortube just like we would! Found this out once I compared it to a normal unit. No hint of ribbing and the walls are super thin and you can see 2 slits of daylite where each stator is attached!:eek: ;)
Instructions say use thin CA on the slits and glue the motor in. Gonna have to as the walls have zero strength, being so thin. But thats okay it'll work fine and I didn't have to do the machining myself. But I had HOPED alfa would have used a bigger motortube/stator assembly.:(
Anyway I sanded alittle, motor fits in, spacerplate almost done w/holes drilled to match cooling holes in the motor, once thats done and rotor centered, Ca motor to stators.
Bruce

[watt_the?!]

hmmmm...we used a star washer in the end and tightened it up so tight that it created pressure on the shaft (i.e. interference fit due to the compression of the material). I think that the star washer mightve fixed it though itself, as it meant that the nut was clamping down on a larger contact area and bedded in via the washer's teeth.

i cant tell you if it was that or the tightness of the fix. i was concerned with it being so tight that it would deform the rotor in some way though.

Tim.

[Bmiller]

Thanks Tim!
We have an assortment of starwashers at work I'll "borrow" some;)
Bruce

[Bmiller]

Happy Holidays everyone!:)
Okay, Mega 16/15/2 is now installed in fan unit.
CA liberally applied on stators and outside mounting ring.
(Very little flex/Unit feels solid)
Question on wire size: motor to ESC, can I get away with 20g or you think its too small? The mega wires are short and I'm trying to attach the tailcone and the solderjoints would be right in the fin of the tailcone.
I guess I could stuff the soldered joints in the 'cone and run bigger gauge wire...What do you think?

[Bmiller]

Okay I decided to go with 16gauge wire.
Soldering begins now!;)
Bruce

[watt_the?!]

http://www.powerstream.com/Wire_Size.htm


look down the max amps for chassis wiring....

16g should be ok...

Tim

[Bmiller]

http://www.powerstream.com/Wire_Size.htm
Tim

Great link Tim! Thanks! I'm gonna save this one!:D
Regards, Bruce

[Bmiller]

4S 2100 16C Impulse pack charged last week sometime.
Mega16/15/2 in Alfa fan.
14.05Volts
24.4Amps
343Watts
56,560rpm

4S 1600 12C Apex pack charged yesterday.
13.39Volts
21.6Amps
289Watts
55,160rpm
Both packs were cold, only ran setup for 10seconds to stabilize readings and take photo.
Gotta maybe balance the rotor as the spinner popped off probably from vibration.

[roccobro]

Hmm.. Bruce, we need to set up an online database for this fan so we can all post data on it.

Justin

[watt_the?!]

4S 2100 16C Impulse pack charged last week sometime.
Mega16/15/2 in Alfa fan.
14.05Volts
24.4Amps
343Watts
56,560rpm

4S 1600 12C Apex pack charged yesterday.
13.39Volts
21.6Amps
289Watts
55,160rpm
Both packs were cold, only ran setup for 10seconds to stabilize readings and take photo.
Gotta maybe balance the rotor as the spinner popped off probably from vibration.

something doesnt seem right here... 54W for 1,400rpm.

from first priciples, delta rpm = delta thrust squared = delta power cubed.

i.e. delta rpm = 56500/55160 = 1.024
therefore delta power = 1.024^3 = 1.075

i.e. power should be 289 x 1.075 = 311W. (not 343)...OR the rpm isnt right.

either one...the only other factor it could be is that at above 20A either the pack or the motor or both is/are running inefficiently.

consider the himax at 19A and 10V for 51000rpm... 190W.

PS not criticising, just posting thoughts.

would love to hear other's.

Tim.

[Bmiller]

That'd be cool Justin!

You're right Tim,Probably the rpms are off on the 1st test. The angle of the flashlight was not good. And I was more preoccupied with my new camera. Fan sound had a much higher pitch than test 2.
And the watts don't lie!;)
I'll tell you what though...The Mega isn't even stressed! I know this motor can handle the load! Also gotta get a 2S 2100 impulse pack to test this monster on 5S!!!!!!Muahahaha!!!!;)
Bruce

[ParkJetsFlyer]

Mega Motorss are only rated to 55K rpm, I'd be VERY Careful running a 15/2 on 5S Your looking at around 85K rpm :(

[Bmiller]

Thanks Tom, Yes the extremely high rpm is a worry, both with the ESC switching being able to handle a 6 pole motor at those rpms and mechanical failure. I think a "meatier" rotor is needed here. That would be the ticket! Justin & Scott are about to test a cutdown walkera rotor(and some other rotors as well)in the alfafan. Still waiting for their results.
Regards, Bruce

[watt_the?!]

personally i think putting other rotors in there is...cool yes, but not going to yield much useful info.

at over 55k rpm its pretty subject to vibrations, so best to go for the next diameter up.

this is where the vasas have an advantage....and, dare i say it, the gws fans.

more aggressive pitch fans.

the more aggressive pitched fans are harder to pick a motor for though aS the margin for error is far less thana lightly loaded one.

T

[ParkJetsFlyer]

I've been thinking about a Mega 16/7/3 (5580K) motor http://www.dynamoelectrics.com/detail.aspx?ID=927 for a bit of time. on a 3S pack, it's rolling along at almost 62K rpm!!
A nice short can motor
Mounted in a Minifan or Alfa-fan might be nice.

[watt_the?!]

i think youll find that that'll give around 54-55k Tom.

[ParkJetsFlyer]

:D Oh, I think I could live with that!! The really nice thing is that the battery and motor will probably weigh about 1/3rd. less than a more "Standard" Mega 16/15/XX set-up would. Know of any Minifan jets that need a light weight make-over?

[Bmiller]

I have to admit I'm kinda lazy and I don't want to rework the ducting or fan bulkhead for another fan. And I've read of rotor problems with the Vasas at hi-power(300watts+) levels. The cutdown rotor is the easiest mod to do/test.
Roccobro tested the 16/7/3 in the alfafan.
These numbers are from memory But should be very close!
3S 54k rpm @ 28A
4S 64K rpm @ 40A

3S Mega16/7/3 would be better than the 2025/5300 for sure and lighter.
But its too hot of a wind for 4S(IMO)
A Hyperion X22s or Y22s5000kv or the new AON 4900kv are possible too.
I couldn't find a maxamp rating for the hyperion. But its probably 25A or less.
Cheers, Bruce

[watt_the?!]

bruce...looks good to me. we tested the hyperion x22s and that was really struggling at about 16A. it managed 45000 on 3s and 20A.....very hot..

that was the 5000k version.

what is the max amps for the 16/7/3...?


oh, max amps for the hyperion is 18A....

[Bmiller]

Mega lists the 16/7/3 at 30A
18A for the hyperions...Thats all! :( Too bad cause they're cheap!($39.95)
Wish the mega had a 5000KV!

[Bmiller]

Hello all!
Sorry for the delay! Been working on some other stuff...:)
Along with my SU-27 I was flying my F-86 w/2nd himax2025/5300 on 3S last saturday and generally having a great time with friends and perfect weather...
Tossed my 4S Impulse2100 16C in and at 3/4 power,threw it, let it fly 75ft, gave it full power, went 90*straightup, leveled plane at 400ft, and then cruised around at 1/2 power to cool the motor, several low level hispeed passes, interspersed with low power passes for cooling, landed, and kept motor running at slowest speed and long story short the motor windings are shorted! :mad: Found this out on next flight w/3S as motor cutout about 10 seconds after launch, recycled esc and landed.
Ampmeter showed 35A on 3S, 25A on 2S! Oh well bye bye Himax!
So anyway that night I installed the Mega/2 fan unit and launched it sunday w/ 4S! Sounded great, went for my full power vertical and after 2-3 seconds of that the motor cutout! No problem, just leveled it out and recycled ESC,applied 3/4 power and flew around while trying 100% power several times, and it cut out everytime after 2 seconds which I guess is the time it takes the motor to spool up to around 60,000rpm...Overall the average flight speed was about 20mph faster than the himax setup since I never used less than 3/4 throttle!And its still very fast at 3/4!!:D
So the darn ESC timing can't handle the 6 pole motor at the rpm level I want. Playing with the timing & frequencykhz increases risk of overheating either the motor or ESC. So I'm looking for a mini480 rotor to cutdown and that should drop the rpm to manageable levels while retaining same thrust or better.

[Bmiller]

Went to the AMA show on Saturday and talked to the Castle
Creations rep Shawn Palmer(used to be in tech support).
He said there shouldn't be any problem with 6 pole motors as he runs a 28pole at 30,000rpm! Told me to turn off current limiting and select soft start. I only disabled the current limiting at the field on Sunday and it worked!
WOT no problem! so I still got unlimited vertical and after the pack warmed up a bit it seemed as fast as my (way over the limit )4S 2025/5300 102mph setup!
And I can WOT the whole flight too! Motor is cool after flight.
A quick amptest after flight, motor draw was 25.1A
Next experiment is cutdown kyosho rotor.
Should bring the rpms down to a safer level and thrust up!
Hope to run somewhere around 400-450 watts!
Bruce

[Bmiller]

Long story short,
I installed a cut down a Kyosho rotor in the alfa fan and off to the field!
Put in my 4S pack and away it went! Silly fast and amazing thrust!
I'd go vertical at min speed and as it stalled, hit WOT and about 3seconds later, level out at 500ft! Pack was smoking hot afterward so I got worried and put in a 3S pack and the meter showed 42A 450watts!:eek:
(After cooling)I recharged 4S pack and meter showed 44A 600watts!!:eek:
So you can imagine how a 24oz EDF flies with 600 watts!:D

But the kyosho rotor is TOO efficient! and its killing my batteries!
Next thing to try is a cutdown minifan rotor, It's got a much larger hub and after cutting it down, hopefully will be less efficient and lower the ampdraw.....
Bruce

[Bill G]

Bruce, a while ago I heard some positive things about Warp4 motors for high power/rpm applications. One author claimed the motor to significantly outperform his Mega 16/15/3 (I think). Was that all advertising hype or do these motors really compare to Megas in these high power/prm apps? Just wondering if anyone has any exerience with them.

We need to start a lipo donation fund for your testing program. Parallel a bunch of Gen1 blue label 2100s. That's gotta get pretty expensive running batts at 40 some amps.

[Bmiller]

Yes I've also read good things about the Warp series but don't have one to torture!;)
As for outperforming Megas I doubt it would be to any significant degree even if true, however I've read they are AS good and alittle cheaper to buy.
I currently own 3 Megas(two16/15/2 & one16/15/3) and have never been disappointed in their performance and quality.
I'm going to fly the AKM(AlfaKyoshoMega) 2 more times this weekend then install the cutdown minifan rotor. I got nothing to lose!
I left the hobby for 3years and missed the entire gen 1 lipo era!:p
Which from what I hear was not a bad thing to miss!

I could 3S2P my 2200s(2P=54Acontinuous) but the Megas rated at 35A anyway so I don't think it would last too long running at over 44+amps.

[termite]

Bruce,
I've got a couple guys run the 2 turn on 4S in minifans at over 60 amps without any problems :p

Your mileage may vary :D

Randy

[Bmiller]

Bruce,
I've got a couple guys run the 2 turn on 4S in minifans at over 60 amps without any problems :p

Your mileage may vary :D

Randy
Randy,
Are the physical dimensions the same as the mega16/15/xx series?:D

My 600watt Alfa is fun!!

Bruce

[roccobro]

I think Randy is talking about the 16/15/x series. :p

Justin

[Bmiller]

I think Randy is talking about the 16/15/x series. :p

Justin
Doh!:p Holy crap! my /2 will handle 60A?!?!:eek:
I've heard 50A or so (in bursts)
Geez, So all I need is a 4S 20C 2500 battery pack????
Mileage be damned!LOL

[Bill G]

Yes I've also read good things about the Warp series but don't have one to torture!;)

I love it!:D
That's the tested tough program. Any good device should at least exceed specs by 200%.

[termite]

Doh!:p Holy crap! my /2 will handle 60A?!?!:eek:
I've heard 50A or so (in bursts)
Geez, So all I need is a 4S 20C 2500 battery pack????
Mileage be damned!LOL

Yes the 16/15/2 at 60 amps.
Now as a dealer for Mega Motors I'm not at liberty to tell ya these things so lets keep it between us.

Seriously I don't recomend it but I know guys that do it.

Randy

I've tried the Warp motors and ya notice I don't sell them. Nuff Said

[Bmiller]

Well that makes me very happy!
I feared I'd hurt my motor and thought it may have shorted some windings since it pulled 44amps when I had expected(guessed) to see 35A or thereabouts!
Hmmmm 5S?;)

[Bmiller]

Well decided I'll leave the ky rotor in for awhile and get some better batteries.
Flew it today and the 4S pack puffed up AGAIN! shrank back to normal in 5minutes so I partially recharged it with the blinky installed and it seems normal.....we'll see!
Don't want to go the 2P route and doubling the pack weight...

[roccobro]

You ever notice the gauge wire comming out of the /2? Monster size, only beaten by the /1 motor. :D It can take it my friend. :)

Sorry to hear about your packs... again. :p

Justin

[Bmiller]

Met up with Turbonut(Scott) and we drove to Roccobros field(Too bad you're working Justin!)And got some flights in.:D
I showed off what 600 watts is like in a 24oz EDF!
That is until the battery puffed up like a balloon!;)
Unfortunately he was showing me what a low close pass with his Alfa Huck looks like when it clipped his transmitter antenna and cut the wing in half!!!!:eek: Scratch one Alfa Huckebein:mad: It flew very nicely too.....

Anyway at the field I disabled the LVC and checked the current limiting settings and found it had changed from disabled to most sensitive???
Whats up with that! With the LVC and the current limiting disabled I experienced no inflight cutouts which made for a much better flight!

[Speed is Life]

Hey Bmiller, good on ya.
Now I don't feel so lonesome for puffing a pack today myself. Similar deal, I was shining my a** with the F-104, hot performance indeed.
-Mike

[Bmiller]

Thanks man! Its the 3rd time its puffed up so its pretty much toast!:p
But 400watts per pound is totally addicting!!!!!:D

[tashley]

But 400watts per pound is totally addicting!!!!!:D

Well, Yeah!

[turbonut]

Hi Mike! Sooo You like the schubie!
Scott

[Speed is Life]

Hey Scott,
Oh I don't just like-I love it.
Trouble is, I set my hair on fire and overdo the poor LiPo!

How are you coming on your F-104?
-Mike

[roccobro]

Ugh. The weather was so nice between sprinkles I wish I had called in sick to meet up with you guys.

Scott- Sorry to hear about your Huck (must have been some sight!) but she had been very good to you so it wasn't a total loss. Not like some who dork their new Alfa on the maiden and have to buy a new one. :p How's the Tx's ant.?

Did anybody get some video?

Justin

[Bmiller]

Sorry Justin no video....
At 1st I thought the huck hit Scotts head and took his baseball cap off but it was the white foam from INSIDE the wing that went wizzing by!
They had like 8 soccer goals setup on the darn field! And only Scott and I were there!

[roccobro]

Yep, thats the place. I used to "land" my B2 in those goal nets. :D

Justin

[turbonut]

Stopped by Pegasus and picked up a new one to day! You should have seen it Justin foam flying everywhere..Yea that huck had a good life..Really 3 of them..who said you cant repair foamy planes.
Scott

[Bmiller]

Cool! You're still in the 3 alfa EDF owners group!;)
Did they have any other EDFs there????