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Old Mar 11, 2002, 11:52 AM
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BigBadWolf_TX's Avatar
Mineral Wells TX
Joined Jan 2001
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flying cube!

Hello all,

I am going to make a flying cube. I have read other posts on this subject, but I have question. Where should the CG be? 30-33% of the chord? I am thinking of making it in a 18" size (each square will me 18"x18"). I am going to make it with large elevons as well as a rudder. I will post pics, as well as a flight report when I am done. If I could just figure out the CG?

Thanks in advance,
Mike Connally

ps. I just got laid off.....any one need someone in international marketing
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Old Mar 11, 2002, 01:06 PM
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Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
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Shurely you mean a flying rectangle.. an 18x18x18 cube would certainly be way outside the box.. wait, it IS a box!
For a plank wing, AR=1, try a 12% c.g. and reflex the elevons.
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Old Mar 11, 2002, 02:39 PM
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rpage53's Avatar
Victoria, BC, Canada
Joined Apr 2001
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A cube would ordinarily be balanced about 40% back from the leading edge with up thrust to maintain the pitch angle. If the CG is too far forward, it will always pitch down.
If you are going to add rudder and elevons (or a typical kite tail), you can start at 30% and adjust back from there.

Rick.
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Old Mar 11, 2002, 03:56 PM
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Azarr's Avatar
Dayton Intl, Ohio, United States
Joined Jan 2000
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Try www.rcmircoflight.com or www.airdyn.com, both have info on the smaller 12" cube.

Azarr
www.ecubedrc.com
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Old Mar 11, 2002, 05:19 PM
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Mineral Wells TX
Joined Jan 2001
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Thanks for the quick replies! How does a flying cube perform? Is it stable?

Paul,
What does "AR" mean. I am unfamiliar with this term. CG should be 2.16" from the leading edge? This sounds awefully far forward. Would you mind elaborating?

Rick,
I would like to shoot for 0 degrees of thrust angle. Are there some weird aerodynamic considerations with flying cubes?

Azarr,
My rcmicroflight subscription ran out last month. I looked at the airdyn site, but couldn't find any CG information.


Thanks again,
Mike
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Old Mar 11, 2002, 05:44 PM
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Poway (near San Diego), CA US
Joined Dec 2000
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A flyer at the San Diego Midwinter had a version using two N20 motors and diferential thrust. No servos!

The is a picture in the San Diego Mid Winter 2002 section on my site.
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Old Mar 11, 2002, 06:46 PM
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Sparky Paul's Avatar
Palmdale, CA
Joined Oct 2000
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Well, the links didn't work for me either..
So I'm presuming from the titles that this thing really is a flying cube..
4 sides covered, ends open.. some sort of ducted fan/propellor in the hole, with
steering vanes inside.
The c.g. should then be... I haven't the foggiest idea!
I'd start forward and see what happens, moving it to the rear until this thing flies.
Given enough power anything can, but in addition detemining which way is the front..
or right, or left!!
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Old Mar 11, 2002, 07:12 PM
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Mineral Wells TX
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Quote:
Originally posted by Sparky Paul
The c.g. should then be... I haven't the foggiest idea!
I'd start forward and see what happens, moving it to the rear until this thing flies.
Thanks paul.....you had me going there for a minute. Maybe I will put the cg on the trailing edge, put an .049 up front, and call it a heli!


I guess I will start at 30%, and work my way back.



Mike
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Old Mar 11, 2002, 07:39 PM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
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Mike
From the reality version of RC MF

The CG on the mag plan is about 9cm back from the LE of the 28.5cm 'chord'

The vertical CG - pretty important apparently - is about halfway between the bottom spar and the motor boom. The motor has 18 degrees of upthrust!

The upthrust balances out the noseheavy CG. Power up makes it climb, power off and it descends. (like any other properly powered and flown aircraft ? )

Saw Lance Liotta fly his inside the National Building Museum - around a 90 foot cube of flying space. He did it, but seemed nervous. The model is very controllable, not too fast. If it gets a wobble on or is turned too tight, it appears to execute a roll or two, which didn't seem to affect progress much.

The RCMF plan is the 11.25" cube. Have heard of one at 13", with a GWS DX-? motor - sounds a lot cheaper. Have also seen shots of one with a CF rod hoop between the top and bottom apexes at the front - prop protector? Sounds a good idea to me!
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Old Mar 11, 2002, 08:44 PM
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Mineral Wells TX
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Thanks Rick,

I just made a 7", free flight, non-powered version with no tail. It weighs around 1 ounce, and seems to fly well with the CG at 40% (2.8 inches from the leading edge).

Thanks again,

Mike
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Old Mar 11, 2002, 08:49 PM
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Palmdale, CA
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Here's the French version.. a flying oatmeal box..
seen at:
http://www.aviationpics.de/mystery/page_12.htm
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Old Mar 12, 2002, 03:56 AM
Old age is not for sissies
Azarr's Avatar
Dayton Intl, Ohio, United States
Joined Jan 2000
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Not sure why the Air Dynamics link isn't working, try www.nyblimp.com, it's the same site. Click on cube kites in the list of hyperlinks and then "when the going gets wierd". There's some info on a "twin" cube Gabe is working on.

Azarr
www.ecubedrc.com
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Old Mar 12, 2002, 04:23 AM
I broke it
David Hogue's Avatar
USA, NC, Clayton
Joined Feb 2001
5,720 Posts
Azarr,

The airdyn and nyblimp links you posted have a comma on the end, which is causing the problem. I didnt see it till I got a 404 either, but these should work:

www.airdyn.com

www.nyblimp.com


Later,
David
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Old Apr 10, 2002, 10:59 AM
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Canton, MI USA
Joined Mar 2001
150 Posts
Flying Cube (ARF) now available at http://www.voltaircube.com/ . It was at the Toledo Expo and demonstrated in Bowling Green. Only need to install a micro receiver, other than that, ready to fly out of the box!

Regards,
wattsup
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