HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Aug 17, 2007, 01:35 PM
Deletedfor proving Nauga wrong
Joined Mar 2005
15,855 Posts
what AOA is the canard surface at RELATIVE TO GROUND when its sitting on 3 wheels?

THATS my point. I may have stated it in an unclear manner...

It could be the right angle in relationship to the wing... and have the nose pointed up enough that the canard flips the plane BEFORE the main wing starts lifting!
fhhuber506771 is offline Find More Posts by fhhuber506771
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 17, 2007, 07:11 PM
Registered User
Joined Jun 2005
2,440 Posts
huber, I reference on the wing's flat bottoms as zero AOA which is not technically correct but the flat bottom of the main wing is parallel to the ground so the flat bottom of the canard is 3.5 degrees more positive and since the airfoils are the same, there is 3.5 degrees decalage. The brief time that the model mushed through the air probably was all due to the main wing getting ample AOA when the nose bounced high. The canard AOA was likely in the stall position at the slow speed. Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Aug 18, 2007, 10:46 AM
Registered User
Joined Sep 2006
795 Posts
is it true that if built right a canard won't stall?
b36roxs is offline Find More Posts by b36roxs
Reply With Quote
Old Aug 18, 2007, 10:54 AM
Bernoulli+Newton=Lift
magic612's Avatar
Somewhere south of Chicago, IL
Joined Jan 2006
1,952 Posts
Quote:
Originally Posted by b36roxs
is it true that if built right a canard won't stall?
Well, I've never been able to make this one stall...
magic612 is offline Find More Posts by magic612
Reply With Quote
Old Aug 18, 2007, 11:08 AM
Registered User
Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
3,930 Posts
Quote:
Originally Posted by b36roxs
is it true that if built right a canard won't stall?
That's not a natural characteristic, it's a REQUIRED characteristic. The plane must be designed so that the canard stalls before the wing. By stalling the canard first, it does not have the ability to pull the wing's angle of attack ("AOA") high enough to stall the wing.

If the wing stalls, then very bad things can happen, such as an airplane that suddenly wants to convert itself in flight to a conventional-tailed airplane, followed by a shower of control surface parts and a stream of expletives from the test pilot, punctuated with some well-deserved comments about the species of the engineer's mother.

It is very possible to build a canard aircarft that can do this, but "natural selection" tends to weed them out of the aerodynamic gene pool. Still, if it's your creation that you don't want to be the subject of this weeding-out, best do your design homework thoroughly.
Don Stackhouse is offline Find More Posts by Don Stackhouse
Reply With Quote
Old Aug 18, 2007, 01:06 PM
Registered User
Joined Jun 2005
2,440 Posts
More Delta Testing

D Squared was taken to the field this morning at 7:30 AM. The wind was about 5 mph. Since we have discussed what caused the canard to jump UP, I wanted to try a couple of DOWN elevator clicks for a fast taxi. The trim caused the canard elevator to move about 1/8" UP for less lift and the main elevator to move DOWN the same amount for more lift. At low throttle, it got airborne and went into a vertical oscillation like it was riding a sine wave. The canard did ROG and the main wing with extra lift followed which dropped the AOA of the canard and caused it to drop,gain speed and rise again etc. Back to zero trim and it floated normally. The wind had picked up and it's direction was variable so I will wait for another time. Also I found later today that my glasses are obsolete.The great part of the morning came when my converted Soar Star aka Mickey Duck was flown. You may recall that it would stall out on the entry to a loop. The 8 cell 1100 mah ni-mh battery pack was removed and a 3 cell 2100 mah lipo was added. The ship lost 1.8 ounces and gained a good 60 watts of power. Also, the COG moved rearward about 1/2". The Mega 16-15-6 now tops out at 18.7 amps and the model easily pulls through a loop. It also, when inverted, will take Down elevator and pull up for the second half of the outside loop. It leaves the ground in 10 feet and will do lots of tricks that it could not do before due to lack of power. Charles
canard addict is offline Find More Posts by canard addict
Last edited by canard addict; Aug 21, 2007 at 10:43 AM. Reason: Changed "neutral controls" to "zero trim"
Reply With Quote
Old Aug 19, 2007, 03:35 AM
EDF Addicted
MustangAce17's Avatar
Ocala,Florida
Joined Sep 2005
5,311 Posts
Sabre Canard

here's what it looks like,switched the vert. stab idea and added a pilot and tricycle lg.still have to glue the canards and supports in and devise the linkages. Just got camera batts today so I that's why I didn't have pics when i first posted,been workin on it since Friday evening. Plan to repaint the fuse and sand it down for a better appearance after a few flights
MustangAce17 is online now Find More Posts by MustangAce17
Reply With Quote
Old Aug 19, 2007, 09:23 AM
Registered User
Joined Jun 2005
2,440 Posts
Ace You are red hot! What does the 62kb view show? I trust that you use the CG Calculator? Did you mention the fan type and power? Best of luck with it. I have new glasses now and a better chance to see the new plane in flight. Got to the field at 7:30 AM with two models but left both batteries in a steel box in the garage. Nothing lost because there was an impossible cross wind with no way to fly into it. Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Aug 19, 2007, 02:19 PM
EDF Addicted
MustangAce17's Avatar
Ocala,Florida
Joined Sep 2005
5,311 Posts
Charles, thanks for the compliment,coming from a master it feels nice The edf installed is a carbon fiber Vasa 65mm that I picked up for $65.00 here on rcg a few years ago but am just getting around to trying out, It runs very smooth and I'm seeing 19 amps and 200 watts with a 3 cell 2070 TP Exteme battery on my whattmeter with a GWS 20x40 inrunner at 3900kv. I believe the view your questioning is the intake and the steering arm for the front lg and battery box is hollow(stock location will most likely have to move). Also, yes I will be using the Canard cg calc since it seems to be very handy. Here's a past idea I shouldv'e used it on because it might have flown instead of smash into the ground
MustangAce17 is online now Find More Posts by MustangAce17
Reply With Quote
Old Aug 19, 2007, 02:21 PM
EDF Addicted
MustangAce17's Avatar
Ocala,Florida
Joined Sep 2005
5,311 Posts
Charles, I hope you have a great maiden with D Squared once the opportunity arrives
MustangAce17 is online now Find More Posts by MustangAce17
Reply With Quote
Old Aug 19, 2007, 09:11 PM
Registered User
Joined Jun 2005
2,440 Posts
Thanks, Ace, It's amazing how well I can see now with my new prescription. I am running out of excuses for not doing the maiden. If I break it, I hope all will forgive me for putting a build log out on an untested model. I knew a big chance was being taken but I hated to not share the experience. I now feel that the main wing should have been more like the Long EZ for lateral stability. The control set up may also be very sensitive with the short wings and coupling. I have the movements at 100% EPA with 50% expo which was changed from 50% throws or EPA with zero expo. A friend said that he thought I needed more movement, if needed, with enough expo to give the same sensitivity I had with 50% EPA. Make sense? any thoughts? Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Aug 19, 2007, 09:30 PM
EDF Addicted
MustangAce17's Avatar
Ocala,Florida
Joined Sep 2005
5,311 Posts
it does make sense,more expo is needed with higher rates- for instance, I set most of my planes at 125 EPA and 50% expo on the ailerons and elev to start.
MustangAce17 is online now Find More Posts by MustangAce17
Reply With Quote
Old Aug 20, 2007, 12:47 AM
Registered User
John235's Avatar
Sydney, Australia
Joined Mar 2006
1,315 Posts
Quote:
Originally Posted by canard addict
Since we have discussed what caused the canard to jump UP, I wanted to try a couple of DOWN elevator clicks for a fast taxi. The trim caused the canard elevator to move about 1/8" UP for less lift and the main elevator to move DOWN the same amount for more lift. At low throttle, it got airborne and went into a vertical oscillation like it was riding a sine wave.
I am not sure what a vertical oscillation is. Is it a pitch oscillation?

If so, I seems like a sign of positive pitch stability followed by safe stall recovery. Can that be interpreted as having too much canard incidence??

Quote:
Originally Posted by canard addict
The canard did ROG and the main wing with extra lift followed which dropped the AOA of the canard and caused it to drop,gain speed and rise again etc. Back to neutral controls and it floated normally.
I am having a bit of trouble with the terminology at the moment.
Does neutral controls mean you take the stick position back to neutral but using the same down elevator trim position? Is floating normally some type of level flight?
John235 is offline Find More Posts by John235
Last edited by John235; Aug 21, 2007 at 06:16 PM. Reason: spelling
Reply With Quote
Old Aug 20, 2007, 12:59 AM
Deletedfor proving Nauga wrong
Joined Mar 2005
15,855 Posts
Yes, a canard should go into a series of pitch oscillations when at "stall speed".
The canard surface should stall, dropping the nose.
Airspeed increases and the nose rises.

That can be due to excess incidence on the canard surface or due to inadaquate airspeed. If the CG is too far forward it would happen at a higher airspeed.

Wing loading, incidence and CG are all factors of the speed when that occurrs for any given design.
fhhuber506771 is offline Find More Posts by fhhuber506771
Reply With Quote
Old Aug 21, 2007, 03:40 AM
Registered User
John235's Avatar
Sydney, Australia
Joined Mar 2006
1,315 Posts
Wing structure completed

I just finished the wing stucture. Now I am trying to finalise the design of the fuselage. I wanted to make a sleeker looking tail fin profile, but instead I chose to keep the motor closer to the GC. Fortunately the motor only weighs 46g (1.63oz) including prop. If it goes well, I might want to fit a larger motor and battery. Hopefully the CG will come out somewhere close to where it is supposed to be.

I used the Canard COG web calculator using 10% static margin. It suggested the COG needs to be around 5-10mm in front of the wing leading edge - Thats around the tip of the wing dowel.
John235 is offline Find More Posts by John235
Reply With Quote
Reply


Thread Tools