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Old Jun 03, 2013, 08:27 PM
Registered User
United States, MN, Mankato
Joined Apr 2013
28 Posts
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Increasing stability in wind with wing tip weights?

I have a foamie that does pretty well in the wind for a light plane but I'm still hoping to fly in higher winds. The throws can be set pretty high and the CG extra forward but the issue I struggle with most is side to side gusts.

Would adding wing tip weight over the CG benefit me or should I focus on more weight lower (below) the aircraft to act like a pendulum?
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Old Jun 03, 2013, 11:42 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,313 Posts
Instead just get used to the plane kicking around in turbulence. It's not harmful and it seldom lasts for long. And the next bump will often tend to correct any disturbance from the first one.

Adding weight brings up worse problems than it cures. First off when you DO need to make a correction it requires more control throw held for longer to over come the inertia from the disturbance. So you actually end up working harder to keep it more or less level.

Adding weight also increases the stall speed. That means during the landing approach the effect of the ground shear where the wind speed drops during the last 6 to 10 feet that your model will need to be flying that much faster to avoid "the bottom falling out" where you experience a stall before landing due to the wing velocity shear effect leaving the model with too little airspeed.

It sounds odd but moving the CG ahead makes the model MORE pitch stable. But that is the last thing you want when flying in turbulent windy conditions. It means that every slight gust that momentarily makes the plane feel like it's flying faster is going to result in a stronger nose up reaction.

Instead you want to move the CG back and re-trim the elevator until the model shows only minimal pitch stabilty. You still want SOME but try to learn to fly with as little as practical. In response to this setup the model will respond to sudden velocity gust effects with minimal pitching action. And that reduces your workload.

In short you don't want to modify the model to fly better in the wind. INstead you want to alter and develop your piloting skills to learn to deal with the wind where needed and ignore it the rest of the time.
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Old Jun 04, 2013, 05:24 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,034 Posts
As BM says is the better way to go, the more you practice the better you can fly in various conditions.

But that said, you can 'cheat' a little by fitting a gyro to automatically smooth out some of the models reactions to turbulence. There are also full 'stabilizer' systems, (basically multiple gyros modules), OrangeRx RX-3S etc, even receiver with it all built in available for control of multiple surfaces, Spektrums AS3X etc.
To some fliers they are 'the best thing since sliced bread', to others they take away some of the skills we learn, and the reasons we enjoy the whole aspect of the hobby so much.
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Old Jun 21, 2013, 01:07 AM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
As BM says.

I would just add that neutral pitch trim provides max pilot control. It also lowers the stall speed, making it easier in turbulent conditions and on landing etc. Move the CG back untill trajectory is straight in the dive test.
It's more or less the same as Bruce was saying, expressed slightly differently.

There is a prevailing mythology around the alleged benefit of a forward CG - a bit of an old husband's tale methinks................

However, not contradicting all the above, Dynamic Soaring flyers do load up the wing tips of their craft. But these are exceptionally high wing loading models that fly in high wind conditions and at extreme speeds. It provides some improvement of stability while flying through the sheer layer. See the DS threads for some of the science behind this, if you are not already familiar with it. Strong stuff!
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