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Old Apr 29, 2007, 03:56 AM
who has rabbit ears down
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United States, MN, Buffalo
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Shook up

Had our shakedown, today, small tweaks neccesary. Will be finished with blue butyrate on fuse! Maybe next weekend??
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Old Apr 29, 2007, 07:34 PM
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Solarsail's Avatar
United States, CA, Santa Monica
Joined Feb 2006
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What a beautiful rainbow-colored canard~,~. Great idea on the scheme.

What's the power source? There seem to be odd things underneath and at the rear.
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Old Apr 29, 2007, 07:37 PM
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Toronto (Don Mills), Canada
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Quote:
Originally Posted by Solarsail
What a beautiful rainbow-colored canard~,~. Great idea on the scheme.

What's the power source? There seem to be odd things underneath and at the rear.
This should fill in the gaps:
http://www.rcgroups.com/forums/showthread.php?t=678704
Pat MacKenzie
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Old Apr 29, 2007, 08:20 PM
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Ah, EDF. I thought there might have been a turbine under there ~,~
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Old Apr 29, 2007, 08:45 PM
who has rabbit ears down
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United States, MN, Buffalo
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Howdy Gang!-Solarsail!
I can't even tell ya which motor this is, other than the Hobby Lobby ball bearing Brushed motor that has reports that go forever-Bein'a newbie to electric, Craig told me the name, but of course- I didn't bother writing it down- Phasw one of a ducted fan sailplane platform new info will be here, at electric sailplanes!
Johnny
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Old May 01, 2007, 05:17 PM
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Cebola's Avatar
São Paulo - Brazil
Joined Apr 2004
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Quote:
Originally Posted by Captain Canardly
Howdy Gang!-Solarsail!

Hi Captain Canardly

Despite my avatar is a cannard model, I never found the correct position of the CG.

Can you give us a tip?


Cebola
Brazil
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Old May 01, 2007, 09:02 PM
who has rabbit ears down
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ABSOLUTELY GANG!!
without using all that engineering terms, here we go;
As a Canard uses 100% of horizontal area for lift, we will use percents for the base of calculations with a sketch as reference;

1) Main wing square inches=XX
2)Main wing quarter chord =sub(little) c
3) Canard square inches= XX(canard)
4)Canard quarter chord= subc
5Distance of mounting =Length using quarter chord locations;
NOTE- I personnally like my spars to be perpendicular to Length, at the thick point of foils, and I use the (Spar)- wing rod for distance references

just using math, we will assume a main wing of 500 sq" and canard of125 sq"
main plus canard =625 sq"
Length of mounting we will use 25"
To get our Neutral point, we go length multiplied by Mainwing-25x500=12,500(
)divided by total sq."= 20 "
Still with me? the length 20 inches is our NEUTRAL POINT from the Canard's quarter chord towards the main wing Length, which would be a distance forward of the Main Wing leading edge
NOW THE CRITICAL PART
The STATIC MARGIN= ( ENVELOPE) this will establish the aircrafts' stability of flight.
for the most forward Center of Gravity, we will use 15%, and for flying "the ragged edge" we will use 10%
We have established that 20 inches from Canard Quarter chord is the neutral point,
Now we need the (bar sub C) which is the proper termfor the Mean Aerodynamic Chord= MAC which is average chord, being square inches divided by span.
We haven't established a span in our calculations, yet, so we will go with 50 inch span, for math, we are using a rectangular wing, 500 sq" divided by span of 50" gives a MAC of 10 "
Now the STATIC MARGIN'S calculations are 15% of 10" MAC, PLUS the 20"= 21.5", Right?? actually no.
AS the neutral point of aircraft would be considered ZERO, forward of neutral point
would now be calculated in the negative, meaning the 1.5" is subrtacted from our 20" Neutral Point=18.5" and at 10%, 19 inches from Canard's Quarter Chord.
This would be the ENVELOPE
Did I come across clear as mud? Obviously, I willneed to update/ edit future details, in the morning -Igotta goto work, now
Johnny
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Old May 02, 2007, 08:02 AM
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Here's a sketch
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Old May 04, 2007, 05:10 PM
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São Paulo - Brazil
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Quote:
Originally Posted by Captain Canardly
Here's a sketch

Hi Captain!

Thanks for the tips.

In fact I love canard models, and I think now its possible build one.

Something like the drawing below.

Can you make a evaluation?
Good trip?
Bad trip?

Regards


Cebola
Brazil
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Old May 05, 2007, 06:33 AM
who has rabbit ears down
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Cebola!
Your Welcome! I hope I did'nt cause too much confusion- After I get Bill Kubiak to rewrite the "king's Math", I'll post that.
Now then, very clean lines, but we need a couple small adjustments.
I'm relearning a cad program, and what you would want is a 4 point conic section, and play the fourth location to get something as the (enclosed). I've had two bent birds, and it either breaks in the center of fuse, or right behind the canard drive cutout, which subtracted quite a bit of nose strength.
I believe you could easily take what you have, and reverse the fuse to the flying surfaces- you already have the right shape!
Add a bit of dihedral, not much, just a few degrees, or have a break out at 75% span
and about 2.5" lifted.
Add some dihedral to the Canard, too, what happens in a turn, is what kills lots of EZ pilots, like John Denver, as when airspeed gets too low, with the flat plane (dihedral), there won't be anything to help the nose recover from it's dropping tendancy. I usually like 15% included.
Your inclusion of vertical area is a sweet Idea, I'm Glad your executing it, as I've decided on "my" shape.I suspect you be stucturing/ fairing and mounting to the wing in 2 places??
here's a canard mounting shot or two!
More later!!
Johnny
I have severe editing to do in photos- more later!
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Old May 15, 2007, 03:13 PM
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Scotland UK
Joined Jan 2005
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Tracker 100

New model, limited production UK model. Motor,ailerons,flaps,Vtail ruddervators.
It flies very well indeed
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Old May 15, 2007, 07:12 PM
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São Paulo - Brazil
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Quote:
Originally Posted by sandist
New model, limited production UK model. Motor,ailerons,flaps,Vtail ruddervators.
It flies very well indeed

Hi Sandist

Is your model a balsa fuse, or Lite ply, just in case can you tell something about it?

Regards

Cebola
Brazil
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Old May 16, 2007, 06:03 AM
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Scotland UK
Joined Jan 2005
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Hi
Tracker has a kevlar fuselage, moulded wings, huge flaps and ailerons.
megas motor,4.4 maxon gearbox,17 x 11 propellor, CC Phoenix 45 speed controller,
2100 4s lipo. Draws about 32 amps
weighs about 1900 gms, it is set for the UK 200w/kg class therefore the climb is lethargic to about 8/900 feet in 30 seconds

It flys very well ,responds to lift and handles our blustery and frequently turbulent conditions.

Ian
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Old May 20, 2007, 08:59 PM
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United States, MN, Buffalo
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The weather guys were off, again!
She flies beaufifully! just right combo! about 75 ft /min climb, used the bottom of the battery, for three check flights, had the trims dead on at first flight, thought I'd add some 'up', but not neccessary, as this induced the pitch moment to wobble a bit. during recharge, the front came through, which gave us 20 mph winds and 20 degree temp drop. got about 6 photos on a SLR Pentax, will post at next finished roll /flight.
Johnny
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