H-9 Corsair 60cc shimmies in flight
#27
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https://www.grc.nasa.gov/www/k-12/airplane/move.html
#28
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Wow, this thread went a little nuts, by the way I had a maiden flight (actually 2 flights) my H9 60cc Corsair last night. Guess what, I have the tail waggle too, and I'm perfectly fine with it. I am now flying with 3 others in our club with Giant Scale Corsairs (all three top flite models) and they have it too.
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The reason the tail "shimmies" in flight is because it is an unstable design. The model sets up an oscillation around the yaw axis and you see it as a shimmy
Larry B.
Larry B.
#31
When you really look at them, all fighters are unstable. A low wing design has just enough dihedral to keep it upright without constant inputs from the pilot. The classic midwing Wildcat and modern F-16 Fighting Falcon have no dihedral at all. Almost all modern high wing designs have some anhedral in the design to reduce stability. The thought is that designing the planes just at the edge of being unstable makes them react quicker to pilot input and, therefore, more effective at combating other aircraft when called upon to do so.
#32
I have the CARF Corsair, it's put together properly and it too exhibits some instability in the yaw axis though I only notice it at cruise speed and above. That's 80 mph to 120 mph to be precise.
#34
From my experience with flying RC Corsairs and watching others fly Corsairs, the tail does not wag when the head wind is dead on the nose. If the wind direction is off the nose, say approximately 5 degrees to 90 degrees, port or starboard, this is where the tail wag seems to be more pronounced. Beyond 90 degrees and including a direct tail wind, the tail wag does not appear. This is what I have observed over the years with RC Corsairs with wing spans from 39'' to 100+".
Roger
Roger
#35
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You feel better now Dan? I don't think I mentioned anything about movement over the earth or the fluid of air, or angle of attack or vectors of air or anything else mentioned in your post other than maybe misusing the term "headwind".. Which I'm still not sure I used incorrectly.
When I'm flying in the direction the wind is coming from the tail shakes more.
This RC pilot thanks you for the informative post, but the tail still shakes no matter how I describe it and your post really didn't help explain why.
When I'm flying in the direction the wind is coming from the tail shakes more.
This RC pilot thanks you for the informative post, but the tail still shakes no matter how I describe it and your post really didn't help explain why.
So while you may be flying "into" a "headwind" relative to the wind at your windsock location, at the airplanes altitude and location, its very possible that its encountering a quartering headwind, crosswind or in severe cases a tailwind.
#36
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Can we just sum it up to the fact that Model Corsairs are "sensitive" to wind conditions and leave it at that?
Unless someone is going to head over to a wind tunnel and get scientific then really nobody knows for certain the whys and hows and basically who cares!!
Its sensitive to wind so be carefull and keep it in mind when flying. I know even at the slightest breeze a tail wind landing or take off is not advised, been there done that.
One field I fly at is so turbulent that you just fly the general relative wind where you stand and just deal with it. We have a row of tall trees parallel to the runway about 150ft back. Theres a 100ft deep gravel pit at the eastern end of the runway behind a 20ft high burm and chainlink fence. Theres a fence to the west thats low. Theres a railroad track to the north and a couple trees. At any one time the wind sock can show 90 degree cross winds and then go slack and change 180.
The eastern approach I call the carrier landing because you have to be under 5 feet above the burm to hit the first 25% of the runway. That means a downward swirl just as you pass over to be prepared for and slight upward gust just after.
This is where I learned to really fly the Corsair and its more than capable to handle wind in any direction.
Just dont land with full flaps and try to taxi for a long distance as they partially blank out the rudder when you need it to steer at low speed. I learned the hard way. Raise the flaps as soon as your settled to gain more control as you slow it up.
My friend decided to sell his H9 Corsair so I wont have a chance to learn more about that plane any time soon.
Unless someone is going to head over to a wind tunnel and get scientific then really nobody knows for certain the whys and hows and basically who cares!!
Its sensitive to wind so be carefull and keep it in mind when flying. I know even at the slightest breeze a tail wind landing or take off is not advised, been there done that.
One field I fly at is so turbulent that you just fly the general relative wind where you stand and just deal with it. We have a row of tall trees parallel to the runway about 150ft back. Theres a 100ft deep gravel pit at the eastern end of the runway behind a 20ft high burm and chainlink fence. Theres a fence to the west thats low. Theres a railroad track to the north and a couple trees. At any one time the wind sock can show 90 degree cross winds and then go slack and change 180.
The eastern approach I call the carrier landing because you have to be under 5 feet above the burm to hit the first 25% of the runway. That means a downward swirl just as you pass over to be prepared for and slight upward gust just after.
This is where I learned to really fly the Corsair and its more than capable to handle wind in any direction.
Just dont land with full flaps and try to taxi for a long distance as they partially blank out the rudder when you need it to steer at low speed. I learned the hard way. Raise the flaps as soon as your settled to gain more control as you slow it up.
My friend decided to sell his H9 Corsair so I wont have a chance to learn more about that plane any time soon.