decrease dihedral at high speed
02-27-2005 | 06:45 PM
#2
RE: decrease dihedral at high speed
Who wrote that?
Send em back to school.
If the model was designed with CORRECT dihedral ( may or not be right ) the speeds we see will not be a factor.
Send em back to school.
If the model was designed with CORRECT dihedral ( may or not be right ) the speeds we see will not be a factor.
02-27-2005 | 07:25 PM
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From: Orlando, FL
RE: decrease dihedral at high speed
My bad - I should have explained more.
It was discussing how a full size aircraft would benefit from reducing its diherdral as high speed increases.
It was discussing how a full size aircraft would benefit from reducing its diherdral as high speed increases.
03-02-2005 | 08:41 PM
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From: Moreland, GA
RE: decrease dihedral at high speed
Even with full size aircraft, dihedral is not a factor in speed (drag). Dihedral affects lateral stability (the tendency to roll away from a sideslip) and nothing else.
What the article may have made reference to is the fact that if wings are swept back, like most jets, the sweep adds considerable dihedral effect, and often actual dihedral is reduced, or the wings even drooped. But this is for handling qualities rather than drag reduction. Dihedral doesn’t affect speed.
What the article may have made reference to is the fact that if wings are swept back, like most jets, the sweep adds considerable dihedral effect, and often actual dihedral is reduced, or the wings even drooped. But this is for handling qualities rather than drag reduction. Dihedral doesn’t affect speed.
03-02-2005 | 09:37 PM
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From: St. Charles, MO
RE: decrease dihedral at high speed
Lou perhaps they were referring to handling qualities. Wouldn't it reduce sensistivity to Clbeta at high speeds but then it might not be enough at low speeds.
03-03-2005 | 01:51 PM
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From: Moreland, GA
RE: decrease dihedral at high speed
It’s hard to answer a question that is vaguely asked, however if handling quality is the factor, it certainly can make a deference especially if the wing is swept. Lateral stability does change with angle of attack (speed) for a swept wing.
Aircraft that are certified under FAR Part 23 must demonstrate positive lateral stability up to maximum power, and at speeds from 20% above stall to maximum speed. The requirement for positive lateral stability in the landing configuration often establishes the design, and it may mean it will be higher than desired in cruise for swept wings. Although the various approving agencies try to define it, handling qualities are really pretty subjective.
For our model aircraft there is a much wider range of acceptable response, and if the airplane is barely flyable some will think it’s great.
Aircraft that are certified under FAR Part 23 must demonstrate positive lateral stability up to maximum power, and at speeds from 20% above stall to maximum speed. The requirement for positive lateral stability in the landing configuration often establishes the design, and it may mean it will be higher than desired in cruise for swept wings. Although the various approving agencies try to define it, handling qualities are really pretty subjective.
For our model aircraft there is a much wider range of acceptable response, and if the airplane is barely flyable some will think it’s great.
03-03-2005 | 02:09 PM
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From: St. Charles, MO
RE: decrease dihedral at high speed
...... and if the airplane is barely flyable some will think it’s great.
I find myself there more often than I will admit here! And of course it's always the airplane's fault when I am flying :-)
I find myself there more often than I will admit here! And of course it's always the airplane's fault when I am flying :-)
