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aeajr
477 Posts |
 Posted - 08/31/2006 : 09:07:46 AM
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When flying in 10 mph winds with my Spirit 2M, 38 ounce RES sailplane, or my Sagitta 600 2M RES, I find the planes hard to handle and they won't penetrate very well. Thermal hunting can be tough under these conditions. Because it is heavier, my 2.9M airtronics Legend, at 80 ounces does better in the wind both from a stability point and a penetration point of view.
Since the Spirit was my first sailplane, it was all I had to fly. Before I started to play with ballast, I would have to skip windy days and resort to flying my electric planes. But I really wanted to fly the Spirit. Even if I braved the wind, it would be hard to handle and hard to land due to ground turbulence. If I caught some lift, I would have to escape early or risk getting stuck down wind.
I have found that if I add about 10% ballast, if I increased the overall weight of the plane by about 10% I could start to get some positive effect. My Spirit is about
38 ounces, so if I add about 3-4 ounces, the plane goes from hard to control to a much more manageable plane that I can actually fly and land in some wind.
Now, I am talking sport flying, not competition. The most I have ever put in the Spirit is about 6 ounces. For competition purposes you might want to put in more to be able to get better penetration.
Whatever you use for ballast, you want to place the ballast directly over the CG so as not to change the CG of the plane. That was tough with the Spirit as the servos sat there. However during a repair I moved the servos forward. This had two benefits. It allowed me to remove 3 ounces of balance weight from the nose. On lighter lift and lighter wind says, the lighter plane flies better.
I then put in a Velcro loop directly over the CG. I use this to secure the ballast. However I have used packing tape to secure ballast in this and other planes. I have used battery packs, strips of lead or a tube of coins as ballast. Anything that is heavy and can be secured in the plane will work. Most people use lead in one form or another. Just make sure it is secure. Having ballast shift in the air can turn a gentle flyer into a handful in a hurry or make the plane totally unflyable, causing a crash. Make sure it is secure!
Many people have thin walled brass or aluminum tubes that are filled with light weight balsa or foam plugs. When they ballast, they replace some of the foam
plugs with lead plugs. They put them in a sequence that will put the weight over the CG. The more lead plugs, the more the ballast weight.
Be aware that when you ballast your plane you have increased the wing loading so it will fly faster. As such, it is going to need to land faster. Get enough ballast into the plane and your floater can become a fairly fast landing plane. Just be prepared for it. Also remember that the extra weight will place extra stress on the fuselage when you land so a landing angle that has worked fine all along might over stress a lightweight fuselage.
If you winch launch it, be especially careful on the pedal as the extra weight, combined with the wind, will place greater stress on the wings. When I am launching in strong wind, I usually go lighter on the winch pedal to reduce the stress AND to take advantage of the kite effect. You want the wind to kite the plane up so you can pull in less line. If you balance it right you will get a higher launch since there is more line to allow the plane to go higher before you release or zoom the plane.
Give ballasting a try!.
It is best to play with it in a large field when the wind is up but not too gusty. Run some launch and land drills and get a feel for the plane before you start to venture out too far. Over confidence will cost you a plane or at least a trip to the building table. With all that lead in its belly it will fly differently. Be prepared for it.
There are many rules of ballasting that are quoted by pilots. Some will say you have to increase wing loading 2 oz/sq foot to make a difference. Others have told me that less than 20% of the plane's weight is meaningless.
Six ounces in my Spirit is about 15% of the plane's weight and takes the wing loading up about 1.3 oz/sq ft to about 8.4 ounces. I find it makes a significant difference in my ability to fly in windy or gusty conditions. Your experience may vary.
My Legend, at 80 ounces and about 13 oz/sq ft of wing loading has never shown any need for ballast, even when I have flown it 20 mph winds. Every plane is different and every pilot is different. Experiment and discover what works for you whether you are trying to be more competitive, or just trying to get in more fun flying time. When the wind is up, adding some weight to your plane may allow you more flying time.
Best regards,
Ed Anderson
aeajr on the forums
Long Island Silent Flyers |
Best regards,
Ed Anderson
Long Island Silent Flyers
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Edited by - aeajr on 04/01/2009 05:36:27 AM |
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Using Ballast
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