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Normal Topic Canard Difficulties (Read 298 times)
staubkorb
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Re: Canard Difficulties
Reply #6 - Jul 13th, 2022 at 9:12am
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Late to the party, but...

Larger canard as already mentioned and add dihedral to it.  You can possibly reduce the added dihedral you put into the main wing back to the original angle.  I do see misalignment in both the canard and main wing and the right panel of the canard is wider at the tip than the left.  All of this WILL affect performance.

Canards in FF are extremely finicky as the foreplane is the critical control surface making the plane very speed sensitive.  ANY difference in speed requires a different trim setting at the canard.

I built a series of the SAAB Viggen as catajets and they all flew quite well, but launching was tricky.  Had to launch nearly level, with the model banked about 45°.  Theyy did get decent height, but I was not really impressed.  I build another, enlarged about 20% with a "loaded" canard that blew flat on launch and, as speed diminished, gradually loaded down to the glide trim setting.  I was able to launch this model at 60° elevation.

For rubber power, it is probably best to trim for a light to moderate spiral climb and try to keep the speed just slightly above the glide speed.  My RUTANGO canard twin is a very good flyer with no "moveable" surfaces - climb speed and glide are nearly identical.
  

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Sky9pilot
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Re: Canard Difficulties
Reply #5 - May 12th, 2022 at 10:15pm
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Sounds like you're getting a handle on it AK.  Glad to hear the progress!  Helps me if I ever get to completing my Beechcraft Starship!
  

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Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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alfakilo
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Re: Canard Difficulties
Reply #4 - May 12th, 2022 at 1:07pm
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OK...some improvement! Replaced the canard with a slightly larger one, no dihedral, same incidence. Replaced both wings with 1/16" sheet wings, no camber and lots of dihedral. Also replaced vertical stab with a larger 1/16" sheet one.

Ended up with a consistent wings level flat glide. Launching seems sensitive, held glider at the Cg and more or less gently pushed it forward. Aggressive 'throwing' didn't seem to work.
  
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alfakilo
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Re: Canard Difficulties
Reply #3 - May 12th, 2022 at 6:49am
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Sky9pilot wrote on May 11th, 2022 at 6:16pm:
Joshua Finn has this video on trimming a canard:


The large glider showed similar instability to my glider so I'll try his suggestions. Also considering replacing the vertical stab and canard with larger ones.
  
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Sky9pilot
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Re: Canard Difficulties
Reply #2 - May 11th, 2022 at 6:16pm
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Joshua Finn has this video on trimming a canard: Click Here
  

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Kerak
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Re: Canard Difficulties
Reply #1 - May 11th, 2022 at 3:27pm
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Might try masking tape-attached cardstock control surfaces...just to experiment...

Neal
  
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alfakilo
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Canard Difficulties
May 11th, 2022 at 10:04am
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I built this as a test glider for the Hs P75 project. Wingspan is 10".

Cg is behind the rear canopy above the 'cross' decal. Initial tests were terrible...spiraling nose dives into the ground. Hand launch only.

Can you see any obvious mistakes? Disregard canard alignment, no shim to hold its position. Side view shows canard incidence. No thinking went into wing construction, just dinking around. Intent was an airfoil with washout at the tips.

No idea what would happen if I tried to catapult it.
  

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