I actually meant that I add positive incidence, like you. My mistake.fanjiatian wrote:Interesting! It's really cool how filght characteristics are so different for each glider and design. Negative incidence usually causes my glider to do a hard crash at the transition. I actually build a bit of positive incidence before trimming to avoid breaking my glider on the first flightAtRi wrote: While I do stand corrected in that adding/subtracting ballast should be the primary change when balancing the glider, I disagree that the glider should always be at 0-0 incidence. I always add a little bit of negative incidence to my gliders and I have had great success. I find it to be more of a balancing act between adding/removing ballast and adding/removing incidence, rather than strictly one or the other.
Adding ballast definitely has an enormous impact on the glider
From the soinc.org FAQ:wiseowl63 wrote:In regards to the "bubble" glider design. Has anybody ever heard of this glider and does anyone know where to find the schematics for it. Also what classifies a glider as canard.
"01/01/2014 - 20:38 What are the exact specifications needed for a glider to be considered a Canard Configuration?
There are two horizontal aerodynamic surfaces in elastic launch gliders. The larger surface is the primary source of lift and is considered the "wing." The smaller is a stabilization source and is considered the "horizontal stabilizer." Canard configurations place the horizontal stabilizer in front of the wing (reverse that of traditional layouts.) No aerodynamic surfaces may be behind the main wing."
As for the bubble glider I have no idea.
Poudre High School, Fort Collins CO.
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I'm sorry, it was me that started the "bubble" thing. I think the team I asked what design it was, gave me a bum steer. But after some research I think they may have had a Chuck Marko's Scholastic Glider design or a derivative of it. The wing looks like what I saw and the fuselage was long, longer than FreedomFlight's.wiseowl63 wrote:In regards to the "bubble" glider design. Has anybody ever heard of this glider and does anyone know where to find the schematics for it. Also what classifies a glider as canard.
In what direction is the carbon supposed to be aligned for the fuselage?
http://www.amazon.com/EPISIZE-CARBON-FI ... B002IZJ8FI
Also, has anyone experienced significant launch differences based on different positions of the launch hook?
FYI... I'd estimate that the vast majority of regional competitions have NOT been held yet. Most regionals are in Feb / March.goswal wrote:...... now that regional competitions are mostly over?
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Canards are inherently longitudinally unstable. The Neutral point and the center of gravity are not the same as the "standard" configuration. So changes in the canard are far more sensitive then changes in a tail on the standard configuration. Thus, less forgiving.goswal wrote: It seems that our canard gliders have a much smaller "sweet spot," and require a near-perfect launch angle and bank for a proper transition....Also, has anyone experienced significant launch differences based on different positions of the launch hook?
That being said, moving the wing along the fuselage to bring the Neutral point closer to the center of gravity will reduce the instability but not eliminate it. However, a less forgiving launch and transition can be achieved.
Poudre High School, Fort Collins CO.
See the Canard Design Calculator link I posted in a message on page 3 of this forum. If the center of gravity of your glider is properly located relative to the neutral point (do you have enough clay on the nose and not too much), your issue is probably inadequate positive foreplane incidence. I have found that almost 3 degrees is needed for my canard design, which has a smallish undercambered foreplane. This is quite a bit more than the typical decalage angle of 0.5 degrees I have found typical of a non-flapper style low-ceiling conventional glider.
As I noted in my previous Canard post on this forum, my best flights with this glider are about 19.5 seconds for a launch height of about 24 ft. I believe that once an issue with foreplane mount flexing is solved, the design may be capable of better flights. I would encourage students to continue testing and researching the Canard design, there is potential, but I cannot share more as this is to be a student design exercise.
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