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Old Nov 06, 2012, 01:47 PM
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TurboRacer's Avatar
United States, CT, Waterbury
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Help!
Trying to fit an outrunner to old FMA Direct Razor 400

Hello! I need to start by saying I have zero experience with flying wings!

I was walking around my attic last night, and found an old FMA Razor new in the box. No electronics, just the airframe.

The airframe has mount for Speed 400 motor.. I'm guessing we're talking about 2000-2002 or so here

My question - what would be the easiest way to mount a brushless outrunner motor to this wing? I have two outrunner motors I already own and I think would be ideal to use, so I'd like to not have to buy another motor. I have lipos, ESC, servos... I really just need to build the thing, and mount the motor.. I'm also planning on adding a CF tube spar to join the wings for more rigidity. I am *hoping* to build a VERY fast wing... Is 100mph possible?! hahaa
I think I can figure out the TX programming and airplane setup, really I just want to know from you guys what you think would be the best way to mount a motor on that wing.. I was planning on getting out some scrap wood and just going to town, but I think others must have done this before and can save me some headaches!!!

Thanks for any help! Looking forward to getting this thing in the air!!
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Old Nov 07, 2012, 06:38 PM
right between the batteries
Justo23's Avatar
Farmington UT
Joined Jun 2010
143 Posts
I would mount a piece of 1/4" ply or a piece of 1/16" metal to the back of it's built in motor mount... then you could mount the motor to that.

I would use this motor, with this prop... but you may have other products in mind

Best of luck,

...oh and i almost forgot. these wings have been known to get bad flutter at high speeds, so some extra CF spars and tweaking may be needed.
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Old Nov 07, 2012, 07:52 PM
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What two motors do you have?
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Old Nov 08, 2012, 09:50 AM
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For motors, I have a Scorpion HKII-2208-28 - http://www.scorpionsystem.com/catalo...22/HK-2208-28/

And I have the BL motor off a Flyzone FW-190 which the site lists as a 41-19-900kV motor and 30a ESC.. I was thinking the Scorpion may be the better fit because of it's size... What do you guys think?

Thanks for the help!!!!
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Old Nov 08, 2012, 12:43 PM
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I think the Scorpion would be the best choice also, especially if you are wanting to make your wing fast. However, with a kv that high, you will limited to a 4" prop.
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Old Nov 08, 2012, 12:58 PM
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4"? That thing is going to scream I think with a 4" prop.. hahaa... I'm willing to try though!

I am going to go to the hobby store tonight and see if I can find a prop adapter and prop for it.. Do I *need* a pusher prop or can I use any prop and spin it around?

What about the battery - I have a bunch of 3S 1300's - think that would be a good place to start?
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Old Nov 08, 2012, 01:17 PM
I'm overcoming gravity!
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You could try your 1300's but you may need larger batteries in order for the wing to balance.
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Old Nov 08, 2012, 02:37 PM
right between the batteries
Justo23's Avatar
Farmington UT
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a regular prop will work just fine turned to push, you will just have to swap 2 of the connections to the ESC if it tries turning backwards.
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Old Nov 08, 2012, 02:42 PM
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Perfect.. That's what I was thinking... Alright.. Hoping my hobby shop has these things in stock and I can start building tonight

Thanks again for the help.. Will post as I go..
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Old Nov 08, 2012, 02:51 PM
Hi I am Mark & I am an addict
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USA, KY, Louisville
Joined May 2007
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Turboracer - I have one of these that flies really well on a 3s1800 and a 2409 bell type motor and a regular 7 x 5 prop. These pusher wings do not need a different prop, just be sure that the letters on the prop face forward.

Also, my Razor seems to lose almost all responsiveness at landing speeds. I tend to make sure that I am lined up for landing before I slow down too much for landing.

Mark
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Old Nov 08, 2012, 08:32 PM
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Quote:
Originally Posted by mthomas View Post

Also, my Razor seems to lose almost all responsiveness at landing speeds. I tend to make sure that I am lined up for landing before I slow down too much for landing.
When a motor is mounted on the front of a plane, it produces an air flow across the control surfaces. Even when the plane slows down for landing, the motor is still pushing air across these surfaces and the plane is still responsive.
With a rear-mounted motor, there is no airflow from the motor reaching the control surfaces so the more you slow down, the less air is flowing across the wing, and the less control you will have.
Larger elevons would help to make it a little bit more responsive at slow speed.
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Old Nov 14, 2012, 12:20 AM
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Well I am trucking along.. Here's one night of work so far:





All that's left to do is attach the elevons, tape the structure, set up the radio profile, and balance it.. I spun up the motor on a battery with about 70% charge and HOLY CRAP that thing puts out some thrust!!!! I could barely hold on to the motor. Can't wait to see it in action. I hope the maiden goes well! Will probably be this weekend!!!
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Old Nov 14, 2012, 05:57 AM
Never trust laughing dolphins
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Quote:
Originally Posted by TurboRacer View Post
Well I am trucking along.. Here's one night of work so far:





All that's left to do is attach the elevons, tape the structure, set up the radio profile, and balance it.. I spun up the motor on a battery with about 70% charge and HOLY CRAP that thing puts out some thrust!!!! I could barely hold on to the motor. Can't wait to see it in action. I hope the maiden goes well! Will probably be this weekend!!!
Looks great, interesting. Did you secure the prop too? It looks loose to me.
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Old Nov 14, 2012, 06:05 AM
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No, the prop was loose in those pics. I may do a zip tie around the stick that the motor is mounted on. It feels pretty sturdy though, I was stressing it pretty good and it didn't even flex. We'll see how it holds up!!
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Old Nov 14, 2012, 01:03 PM
Never trust laughing dolphins
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Quote:
Originally Posted by TurboRacer View Post
No, the prop was loose in those pics. I may do a zip tie around the stick that the motor is mounted on. It feels pretty sturdy though, I was stressing it pretty good and it didn't even flex. We'll see how it holds up!!
I think the motor will be fine, but a loose prop doesn't sound like a good idea. For best thrust it'll definitely need to be fixed to the shaft, right.
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