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Old Jun 23, 2005, 08:10 AM
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Ron Laden's Avatar
Landkey, Devon, England.
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22/30/2 - Midifan

Hi Guys,

I have a Mega 22/30/2 which I am thinking of using with the Wemotec Midifan, this is for another project after I have finished the minifan Typhoon.

Would I be correct in assuming 5S for this setup and values such as amps, watts and some idea of available thrust would be appreciated, also general thoughts on this setup.

Thanks
Ron
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Old Jun 23, 2005, 10:19 AM
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I use that motor on 5S4P Thunder Power lipo, pulls about 900 watts at the start, maybe a bit more for a few seconds. Using the Hacker Master 70-3P controller with a heat sink attached. I had it mounted in the turtledeck of my midi EJF F-18 and the battery partially blocked the airflow and I had some thermal shutdown issues so I added the heat sink, problem solved. A larger area with better airflow probably wouldn't have a problem but a heat sink is just cheap insurance.

No idea on the thrust.
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Old Jun 23, 2005, 10:55 AM
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Thanks Ed, the initial 900 watts sounds good, I am thinking about a 6lb rog model.
The Hacker Master 77 Opto 32 cell is the controller I will be using. I am lucky in having a friend in the machining business, so a heatsink will be fitted as a matter of course, he is doing a stock batch for Gordon and myself.

Ron
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Old Jun 23, 2005, 11:52 AM
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Hi Ron,

Just stick the controller in the Fan outlet, Gordon does this on his Bob-E-Cat. This way you won't have any problems with thermal shutdowns on the ESC

Which model will it be ??

Grts,

Appie
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Old Jun 23, 2005, 12:41 PM
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Quote:
Originally Posted by Appie
Gordon does this on his Bob-E-Cat.
Not these days Appie I was running a Schulze esc in the plane a while ago and that esc was quite happy in the tailcone. However, I have a Kontronik Beat 55-8-30 esc in that model now, and as both of the two Kontronik escs I own don't seem to like like long battery leads or running anywhere near the quoted max continuous current despite only being fed 2/3 the quoted max cell count in both cases, the Beat is mounted in the fuselage, and has had a pair of big (Schulze!) input capacitors added.

Gordon
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Old Jun 23, 2005, 01:06 PM
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Hi Appie, which model? not finally decided but the Hunter is a front runner, so is the Mystere which I think is a very pretty little jet.

Ron
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Old Jun 23, 2005, 03:43 PM
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Quote:
Not these days Appie I was running a Schulze esc in the plane a while ago and that esc was quite happy in the tailcone. However, I have a Kontronik Beat 55-8-30 esc in that model now, and as both of the two Kontronik escs I own don't seem to like like long battery leads or running anywhere near the quoted max continuous current despite only being fed 2/3 the quoted max cell count in both cases, the Beat is mounted in the fuselage, and has had a pair of big (Schulze!) input capacitors added.
Gordon,

Oke, fair enough, but i did copy (on your advice ) that ESC in the tailcone setup for my Midi F-18 and running at 1200W for 5min straight no thermal shutdown of the ESC, so for me its working perfect (MEGA 22/30/3 with HM 77-O-Flight on 8S1P 4400 Polyquest)

Ron,

How about a DH-108 Swallow ???????????????

Cheers,

Appie
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Old Jun 23, 2005, 04:06 PM
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Ah yes Appie .... I remember you asking about the carbon tube mount ... but I didn't tell you I wasn't running that way any more did I

However, I'm going HM77-O-Flight too for all my escs in future. I feel that the Schulzes don't have enough spare current capacity at 55A max continuous when I'm running 50+ amps on 6.2Ah lipos, and they are too expensive these days compared with the hacker masters. But they've done a good job for the past 3 years or so. As for Kontronik, their latest selling point is BEC even on 30-cell escs, but if the esc keeps cutting at below rated max continuous motor current, one hopes that the BEC circuit works to spec.

Your figures for the Mega setup are really interesting, and sound like an excellent affordable hi-power setup. Did you re-work the Midi motor mount for more cooling? Also, did you support the rear of the motor to prevent vibration from cracking the front mounting plate of the Midi mount?

Gordon
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Old Jun 23, 2005, 05:17 PM
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Gordon,

Quote:
Ah yes Appie .... I remember you asking about the carbon tube mount ... but I didn't tell you I wasn't running that way any more did I
It was GOOD advice though Thanks again for that!

Quote:
Your figures for the Mega setup are really interesting, and sound like an excellent affordable hi-power setup. Did you re-work the Midi motor mount for more cooling? Also, did you support the rear of the motor to prevent vibration from cracking the front mounting plate of the Midi mount?
Yes the figures are quite good, in the beginning i was thinking about a high Amp low Voltage setup but after reading some posts by Phil and the other guys i went for the High Voltage Low Amps (= LESS HEAT) solution. I'm glad i did. (the controllers are a bit more expensive though) But less heat is allways preferrable because heat is power loss.

The motor fits quite snuggly into the mount, so i didn't support it at the rear, i will watch this very closely though

What's this STRANGE business of motors dont fitting right into the Wemo's motor mounts ?? is this why the Shubi's are becoming so popular

I didn't have a change to test fly the F-18 though but that will be done in the next few weeks

Oke back to the subject, i think we're highjacking Ron's thread?

Maybe it's better for also Ron to go for a High Voltage (> 5S) Low Amps solution??

Appie
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Old Jun 23, 2005, 05:46 PM
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The /3 is a very good option. My Probe uses 27 nicads with a 30 cell 65 amp opto coupled esc from France. My Wattmeter records 38v at 43a off of the charger. Mega motors have holes drilled in the backplate that will accept a 7/32 Al tube (with a little sanding). 3 tubes with ply spacers support the esc behind the motor. Since the Probe uses a pod, the battery/esc leads are very short. I have no problem with heat or power.

I prefer voltage over amps because lots of smaller (lighter) batteries at 1700 ~ 1950 outperforms fewer batteries at 3300 (heavyer).
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Old Jun 24, 2005, 03:10 AM
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@ Bob: High volts/low curent is a better option, and even more so with lipos which get more expensive as their max current capability increases. I'm thinking of re-wiring my 6s lipo packs to 8s for this reason ... but will need new motors which is sorta slowing things down

@ Appie: Some motors, eg Hacker, are quite a lot smaller in diameter than the inside of the Midi motor tube, and need supporting at the aft end with slivers of plywood. Even a small gap can let the motor vibrate, which can produce stress cracks in the Motor tube.

This thread http://www.rcgroups.com/forums/showthread.php?t=156604 discussed the problem and defined the solution. I originally used a Pletti 22/30/A4SP4 which I think is about the same diameter as your Mega, but then I fitted a Hacker, and shortly afterwards noticed the problem. The Schubi fans come supplied with slivers of carbon fibre which you tape to the motor case, and which support the rear of the motor inside the motor tube.

Gordon
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Old Jun 24, 2005, 03:15 AM
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Thanks for the info guys, I guess from choice I would prefer to run the 22/30/3 but I have had the /2 new and unused for over a year now so I will run with it and put any spare funds into the Lipos and HM-77-O.

I have shimmed and supported the rear of the motor in the Typhoon,s minifan so if the same applies to the Midi I will do the same.

Appie, I have looked at the Swallow, so who knows I havnt finaly decided yet and all the usual considerations like producing scalish intake,s, space for the retracts etc will help me finally decide.

Cheers
Ron
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Old Jun 24, 2005, 03:59 AM
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Hi Ron

Here's a blast from the past! You in 1992

Gordon (back on topic at last )
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Old Jun 24, 2005, 04:45 AM
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Gordon, where did you find that? The Mystere would be a nice EDF subject, I have always liked it, just wonder how much that intake would need cheating.

Ron
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Old Jun 24, 2005, 04:52 AM
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Quote:
Thanks for the info guys, I guess from choice I would prefer to run the 22/30/3 but I have had the /2 new and unused for over a year now so I will run with it and put any spare funds into the Lipos and HM-77-O.
Ron,

Strong point there Ron, one does not throw a brand new motor in the bin just because (maybe) an /3 is a better option. Like Ed said, with a 5S setup you should be able to get some GOOD results

Surprise us................ or get that typhoon flying first ?

We modellers are a strage bunch, one model isn't finished yet and we are allready discussing an other model to build.........hmm makes one think doesn't it

Cheers,

Appie
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