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Old Feb 29, 2004, 08:49 AM
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Turku, Finland
Joined Feb 2004
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Jet for single 700W brushless?

For a while now I've been searching for a ducted fan (preferably a military) jet, but haven't found one that would be close what I'm looking for. I would like it to be an ARF, but I can consider other kits also.

I have two brushless motors (both from Modeltech) and one of them I'm putting on the jet. They are both 700W motors, but the other is 5600rpm/V and the other is 4200rpm/V. The speed controller can handle 120A max and if I remember correctly 80A constant.

So, the jet should be single engined (the real life model can of course have two engines, as long as the model has only one), suitable for one of my motors and it should preferably be an ARF kit.

If you have any ideas which plane I should by, please share me your thoughts. Also I would like to hear which ducted fan unit and how many battery cells I should use in that plane (was thinking something between 12 and 20 cells) etc..

Thanks in advance.
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Old Feb 29, 2004, 01:14 PM
smug in granny panties
monkamarm2000's Avatar
NorCal Silicon Valley
Joined Aug 2002
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what is the can size on those motor's? 400, 480, 500 size.

Barry
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Old Feb 29, 2004, 03:17 PM
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Turku, Finland
Joined Feb 2004
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I don't really know any detailed specs of these motors, because Modeltech doesn't sell these anymore and they have deleted all info from their website. With the motor there came no instructions, so.. I have no idea Only thing I remember the website said these are 700W motors (dunno on what voltage they are tested, probably ~13V, because the max cells the speed controller can handle is 12. It can be used with more cells, but it will not be able to give power to servos anymore).

The can length is 46mm and its diameter is 27mm. It is made so that 540 motor can be replaced with these (the axis is the same size and the screw holes are at the same positions, although the motor is much smaller than 540 motors).


I guess these motors are not the best for ducted fans, because of their high rpm values (the speed contoller has a limit of 100k rpm).

I have tested the 4200rpm/V motor in a RC 1:10 Asso TC10 touring car and with 9 cells I was able to hit about 110km/h. I guess it could have gone faster, but the gear ratio was as long as it could. I could have added more cells, but as the gearing wasn't appropriate I couldn't get all out of the motor. Even it was geared like **** it still had so much torgue that the car spinned very very easily when I applied throttle.


Any ideas if there's any ducted fan units I could use with these motors?


I'm new to these electric jet planes, so any help regarding to which plane I should get is appreciated, thanks.


Edit: the diameter of the can is so much smaller than in 540 motors that it needs an adaptor to fit to the same holes as 540 motors.
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Last edited by Reima; Feb 29, 2004 at 03:38 PM.
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Old Feb 29, 2004, 03:57 PM
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Stavanger, Norway
Joined Feb 2000
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27x46mm pretty much mean they are similar in size to Kontronik Fun480-xx and Hacker B40-xL series.

The one with kv= 4200 => 8-10cell setups using a Wemotec 480Minifan

The other one is a bit too hot but 6cells in same fan should be doable.
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Old Feb 29, 2004, 04:16 PM
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Turku, Finland
Joined Feb 2004
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So the motors doesn't have enough power to run Wemotec Midi Fan properly?

I was thinking to use GP3300 cells, but are they too heavy for the 480 Mini Fan as the thrust ratios of the minifan aren't very good compared to the Midi Fan.

Do you know what happens with the Mini Fan if I give so much voltage to the motor that it reaches >40k (or even more) rpm? Will the thrust increase or is there a point after which it's no use to add more rpm?
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Old Feb 29, 2004, 04:24 PM
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NorCal Silicon Valley
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I use GP's in Mini Fan stuff! There awesome, just drop 2 cells for CP nicad equivilant's for almost the same power but twice the Duration. Actually I like Haldors suggestion of the Hotter motor on maybe 5 GP'? Sound right Haldor? That would be a nice setup for one of Haldors Migs actually.

Barry
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Old Feb 29, 2004, 05:07 PM
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Turku, Finland
Joined Feb 2004
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Any idea where I could get those one Migs?

If someone has one (builded or not, doesn't matter, but preferable with the fan unit included in the package) and willing to sell it, send me email at reima@digip.org

Is there enough room in the Migh for 6-10 cells of GP3300?

Edit: Or how about the Hornet found at this page: http://www.rbckits.com/id73.htm

It sure is cheap (135e with the 480minifan)
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Old Feb 29, 2004, 05:26 PM
EDF Head
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Stavanger, Norway
Joined Feb 2000
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So the motors doesn't have enough power to run Wemotec Midi Fan properly?

No.

I was thinking to use GP3300 cells, but are they too heavy for the 480 Mini Fan as the thrust ratios of the minifan aren't very good compared to the Midi Fan.

Comparing the Minifan to the Midifan is apples and oranges. They are two different animals. With all up weight (AUW) ranging 2-4 pounds the Minifan is usually the right one to choose. The Midifan is used in mainly in 5-8pound EDF's. The GP's are okay for Minifan use, 8GP's will give you pretty good power and decent duration. 8GP's for the 4200 one, 6GP's for the 5600. Power should be about the same but duration less for the 6cell setup.


Do you know what happens with the Mini Fan if I give so much voltage to the motor that it reaches >40k (or even more) rpm? Will the thrust increase or is there a point after which it's no use to add more rpm?


Above 600W you can start looking for a different fan but that isnt required as the efficiency drop isnt that great.

Fan criteria, only a generalizion:
2-4 pounds AUW = Minifan (250-600W)
3-5 pounds AUW = HW609 / HW620 (400-900W)
5-8 pounds AUW = Midifan (600-1200W)
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Old Feb 29, 2004, 05:29 PM
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Stavanger, Norway
Joined Feb 2000
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Any idea where I could get those one Migs?
Is there enough room in the Migh for 6-10 cells of GP3300?


The HalAir MiG29 is available from www.rbckits.com
GP cells will fit fine, 6-8cell optimum.


Edit: Or how about the Hornet found at this page: http://www.rbckits.com/id73.htm
It sure is cheap (135e with the 480minifan)


Very good price and a very good EDF
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Old Feb 29, 2004, 05:45 PM
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Turku, Finland
Joined Feb 2004
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Is it just me being blind or why can't a see the Migs listed at rcbkits.com. I'll send them mail and ask.

The Mig looks a bit better than the F-18, but the F-18 is an ARF kit that would save me a lot of time.

Which one would you buy and why?
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Old Feb 29, 2004, 05:59 PM
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St. Mary, Maryland, United States
Joined Dec 1996
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Quote:
Originally posted by Reima
Is it just me being blind or why can't a see the Migs listed at rcbkits.com. I'll send them mail and ask.

The Mig looks a bit better than the F-18, but the F-18 is an ARF kit that would save me a lot of time.

Which one would you buy and why?
Click "News", it is a new model (for RBC) and hasn't been put in the regular category yet.

They are both appealing models that fly well - a personal choice really. Plus the ARF vs. construction kit. The hornet has the fan mounted inside with duct work leading in and out, the Mig has the fan externally mounted underneath between flat side engine pods. The hornet while internally mounted is still a sport scale representation, they both look great in the air.
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Old Feb 29, 2004, 06:19 PM
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Turku, Finland
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Okay I'll order the F18 from rcbkits, thanks to you all for your help.
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Old Feb 29, 2004, 06:58 PM
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St. Mary, Maryland, United States
Joined Dec 1996
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One other difference - the Mig can be handlaunched, the Hornet pretty much needs a bungee since you'd need to be Shaq to get your hand around it.
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Old Feb 29, 2004, 07:29 PM
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Stavanger, Norway
Joined Feb 2000
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The F18 is handlaunchable but far less so than the MiG29.

F-18 handlaunch (1MB) - www.halair.com/video/f18hl.wmv
MiG-29 (1MB) - www.halair.com/video/mig29hl.wmv
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Old Feb 29, 2004, 07:50 PM
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USA, NC, Greenville
Joined Dec 1999
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Quote:
Originally posted by Reima

...

Which one would you buy and why?
I'd buy the Mig, it looks much better. (And I already have an F-18)
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