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Old Oct 15, 2005, 09:13 PM
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ptglass's Avatar
USA, TX, Live Oak
Joined Oct 2002
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Need CG for an old FMA Razor wing

A friend donated an old beat-up FMA Razor wing for me to practice on. I have no idea where the CG is supposed to be on the thing. Anybody out there with info? Thanks in advance.
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Old Oct 16, 2005, 01:36 AM
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Toronto, ON Canada
Joined Jul 2002
877 Posts
I can't believe I still have the manual.....

C of G is 7", +/- 1/4" from where the leading edge meets the fuse.
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Old Oct 16, 2005, 01:57 AM
Mum is the word!
Joined Jun 2003
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I was refering to a wing Kit of mine that he bought.
Thnx.
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Last edited by klique; Oct 16, 2005 at 11:27 AM.
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Old Oct 16, 2005, 10:43 AM
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USA, TX, Live Oak
Joined Oct 2002
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helicool: Thanks for the info - I knew somebody on here would know.
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Old Oct 17, 2005, 06:46 AM
Rehab is for quitters
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West Middlesex, PA, US
Joined Jun 2001
4,853 Posts
Too bad FMA quit making this model. Its not the fastest in the world but it can take a beating. Mine has over 600 flights and is 4 years old. I've only run speed 400 6 volt as the motor and 7-8 cell packs.
It was my first wing. After I figured out that you need to decrease the throw on the elevons until you get used to it, it has become one of my favorite flyers. I've actually increased the throws up to 120% and made the elevons just a tad bigger.

Dave...
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Old Oct 17, 2005, 01:33 PM
that tree ate my plane
rotccapt's Avatar
oklahoma city oklahoma
Joined Apr 2004
1,647 Posts
i see you found the manufacturers cg but for futer here is a formula for finding the cg on a wing

pm me and i will email you a ms excell doc that i made with this formula so that you just enter 3 #'s and presto cg
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Old Oct 17, 2005, 09:25 PM
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Silicon Valley Calif.
Joined Apr 2005
409 Posts
I have an old Razor Too!

Got it about 4 years ago. Wanted to modify it with extra electronics so I made the mistake of reinforcing the mid-section with fiberglass. She flew too heavy so I put it aside. I did put a 600 motor in the Razor.

Now, I want to put a brushless with lipos in her and have a package powerful enough to handle the extra weight and pull her around the sky at a good clip.

Anyone have any suggestions?
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Old Oct 17, 2005, 11:08 PM
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USA, TX, Live Oak
Joined Oct 2002
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Jeff85: visit this site justgofly.com Vinnie is the owner and he supplies great inexpensive brushless motors and lipos. Get his email address off the site and send him an email telling him all about your wing and what you want it to do and he will make a good recommendation. He flies wings himself so he knows his stuff. He has pusher configured motors that are ideal for wings.
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Old Oct 19, 2005, 02:49 AM
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Silicon Valley Calif.
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Thanks

Thanks bud!
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Old Oct 20, 2005, 10:51 PM
Rochester, NY
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United States, NY, Monroe
Joined May 2004
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Came across this thread while doing my weekly search for JustGoFly to see what you guys are chatting about. PTGlass - thanks for the kind words !

You own a 48" Razor Wing ? That is one of my favorite wings and the second wing I bought after the Wattage Hyperwing. I have my maiden flight on video below. As you'll see from the landing I expected it to land at my feet and it just kept hanging in the air and wouldn't drop. I finally had to dump it in the grass before it went into the street. The Wattage drops like a brick once you remove power.

Razor Wing - First Flight

and this flight after I had crashed it doing about 80mph into a sign post and took a huge chunk out of the front of the wing and when trying to repair it - the glue dried warping the wing - but I tried to revive it here - and ... well you'll see what happened.

Final Flight of the Razor
I had full left when I gunned the motor and it pulled hard right. I killed throttle but couldn't get it slowed enough.

Great Wing ! I'd buy another in a second if I could find it.

Vinnie
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Old Oct 21, 2005, 11:11 AM
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Hi Vinnie,

PM'd you about a Razor.

Steve
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Old Oct 23, 2005, 06:56 PM
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Jeff85's Avatar
Silicon Valley Calif.
Joined Apr 2005
409 Posts
Which motor for my Razor

Quote:
Originally Posted by JustGoFly
Came across this thread while doing my weekly search for JustGoFly to see what you guys are chatting about. PTGlass - thanks for the kind words !

You own a 48" Razor Wing ? That is one of my favorite wings and the second wing I bought after the Wattage Hyperwing. I have my maiden flight on video below. As you'll see from the landing I expected it to land at my feet and it just kept hanging in the air and wouldn't drop. I finally had to dump it in the grass before it went into the street. The Wattage drops like a brick once you remove power.

Razor Wing - First Flight

and this flight after I had crashed it doing about 80mph into a sign post and took a huge chunk out of the front of the wing and when trying to repair it - the glue dried warping the wing - but I tried to revive it here - and ... well you'll see what happened.

Final Flight of the Razor
I had full left when I gunned the motor and it pulled hard right. I killed throttle but couldn't get it slowed enough.

Great Wing ! I'd buy another in a second if I could find it.

Vinnie
Vinnie: I visited your site-It took me about an hour. I loved it! My question is if you read My post #7, with my Razor being on the heavy side what motor and set-up would you recommend?
Thanks
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Old Oct 24, 2005, 06:25 PM
Rochester, NY
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United States, NY, Monroe
Joined May 2004
1,883 Posts
Numbers, Numbers, Numbers

Quote:
Originally Posted by Jeff85
Vinnie: I visited your site-It took me about an hour. I loved it! My question is if you read My post #7, with my Razor being on the heavy side what motor and set-up would you recommend?
Thanks
Thanks for the kind words. I will post the test data for the 450FT tonight or email me at Vinnie@JustGoFly.com and I will email it to you. If you can provide 300 Watts I can get you
77mph and 30 oz's of thrust 319 watts or
87mph and 21.3 oz's thrust at 292 watts or
95mph and 16.7 oz's thrust at 248 watts

That's what I intend to run on my heavy wings.

If you can't provide the high amps - we can drop the amps down with a different prop for :
82mph 13.7 oz's trust at 204 watts

This is a 2250 KV motor. I've been experimenting with a 1700 KV 450 motor that was running my 24 oz wing that is very draggy yesterday. I started with 6x3 prop which was nice but less than 1:1 and ran about 12 amps 3S. Then upped it to a 7x3 for more thrust and about same speed at slightly more amps. This motor can handle 30 amps at 3S. So I upped it again to a 6x4 and speed increased nicely - but still I wanted more. I ended my test at a 7x5. Nice speed, a little better than 1:1 thrust on a fresh pack and only 25 amps on 3S. This motor doesn't have a name yet - and I need to compare it to the 2250KV 450FT motor. I have a suspicion the 450FT is more efficient but won't drive a 7x5 prop at reasonable amps. These 450's are absolutely unreal motors. Check out http://www.JustGoFly.com and I will get that 450FT direct drive data posted.

Vinnie
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Old Oct 24, 2005, 06:44 PM
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Joined Oct 2005
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Calculating the CG for a flying wing

D=CG=((R*R+R*T+T*T)/(6*(R+T))+(S*(R+2*T)/(3*(R+T)))

S=(Root+2*Tip)/(3*(Root+Tip)) distance from nose to the tip (measured along the root cord, defines the wing sweep)
T=Tip Cord
R=Root Cord


For a flying wing use .9 times the calculated value (max. aft CG position), and use .831 (max. forward CG position).

I have used this formula on about 13 different designs and it works ever time. I suggest nose heavy (forward CG) for the first flight, then you can move the CG back and gain responsiveness.
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Old Oct 24, 2005, 07:41 PM
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Silicon Valley Calif.
Joined Apr 2005
409 Posts
Razor Set-up

ptglass; I was looking up info for my old Razor when I initially came upon your thread. There is very little I can find about the Razor and I'm trying to re-vitalize my old one.

I did not mean to highjack your thread. Now that I found Vinnie I think I will start a new thread called; A place for old Razor Wings.

Vinnie; see you in my new thread.
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