Soaring on Windy Days.

[fraggin]

Yesterday, the wind here was outrageous. It was a steady 20mph breeze most of the day, with gusts up to 30mph in the early a.m.

I've flown in winds only a few times with a gentle lady just to see how it handled.

The results were when flying upwind, the groundspeed was minimal and with a series of up and down elevator, she would just stay in one spot and kind of hover in one area. Kind of tricky to hold it there without it being spun around and carried downwind...
But I did notice that the same elevator action of alternating between up and down while traveling down wind did allow it to pick up enough speed to gain enough lift to keep it from crashing. But, it also seemed to get away from me pretty quickly.

I've read posts about using ballasts to give ships enough weight to penetrate winds, but I have never had any expereince with it myself. I can see the logic behind it, but since I'm not that experienced in flying on windy days, I'm failing to understand the dynamics associated with flying down wind with enough ballast weight to fly upwind.

Are there any threads that explain these soaring dynamics?

[DLD]

Thermal soaring on windy days is quite fun, but requires a plane capable of carrying ballast effectively. One very important reason for this is being able to penetrate the wind to get back to the flying field after following a thermal downwind. Flat bottom airfoils are not especially well suited for this. I have used Quabeck airfoils extensively on contest sailplanes for this very reason. They work in all conditions, and carry ballast extremely well.
The other issue is learning how to follow a thermal in the wind. It can be tricky, but that's what makes it fun. You have to let the plane run downwind with the thermal. It can be done in light winds with something like a Gentle Lady, but be careful about going very far downwind, or you'll be hiking for it.

Good luck,

David Layne

[xtc]

Yesterday, the wind here was outrageous. It was a steady 20mph breeze most of the day, with gusts up to 30mph in the early a.m.

I've flown in winds only a few times with a gentle lady just to see how it handled.

The results were when flying upwind, the groundspeed was minimal and with a series of up and down elevator, she would just stay in one spot and kind of hover in one area. Kind of tricky to hold it there without it being spun around and carried downwind...
But I did notice that the same elevator action of alternating between up and down while traveling down wind did allow it to pick up enough speed to gain enough lift to keep it from crashing. But, it also seemed to get away from me pretty quickly.

I've read posts about using ballasts to give ships enough weight to penetrate winds, but I have never had any expereince with it myself. I can see the logic behind it, but since I'm not that experienced in flying on windy days, I'm failing to understand the dynamics associated with flying down wind with enough ballast weight to fly upwind.

Are there any threads that explain these soaring dynamics?

in simple terms,adding ballist increases the wing loading which has a similiar effect as reducing wing area

you pay a penalty on your slow end speed with ballist but your top-end improves

---not to be confuzed with up-wind or down-wind --- thats just in relation to the ground

xtc

[Curare]

I've had some good fun soaring off the lift of a bank of trees, hovering over cars and buildings, losing maybe a foot of height every minute. makes for some longer than expected times, even without finding any thermal lift:)

[little flyer]

Here is an article by Rich B.

A discussion was posted on the RCSE as follows:

I'm heading for a contest this weekend and it looks like it is going to be a howler. Nice weather but wind to 20+ mph. I have flown in this many times but I've never gotten the knack for making my time in these conditions. Others do, so there must be a technique or trick. I'm looking for guidance. Should I ballast? (duh.) Should I move the CG? Should I fly reflexed for the whole flight? Would it be better to fly a shorter wing span or a longer wing span? What's the wisdom from those who relish these conditions?

Here is Rich's reply...

1). First, if your model is real nose heavy, like 2 ounces or something crazy like that, your not going to penetrate even with ballast. So, to give your self half a chance for extended flight time, the model should be balanced close to neutral with a recovery from a dive that takes about the length of a football field or so, (100yards+) or so .

2).BALLAST: If the thermals are very few and far between, high pressure, or early morning or late evening conditions, ballast is a mistake! It just makes you come down faster. The exception is field slope affect . You might need extra weight to get to a slope or stay in the slope affect area once your model arrives there. Now if there is lift, which is probably 95% of the time, only add enough weight to give your model adequate ground speed to move around the sky,ie. come back from positive air, and come back to the landing circle. This is an important point... know how much weight to add to your plane for the given wind conditions. And not an ounce more than you need. I can easily feel 5 ounces in most any plane in the air but I start at 8 to 10 ounces of ballast. And that will change the planes performance. Special note here: It's a mistake to ballast with week winches, lightweight line, or crosswind, downwind launching conditions. You have to pay attention to everything!!!

3). REFLEXING: 10% thick airfoils usually need ballast in winds above 10 to 12 mph. OK... so thinner airfoils will penetrate without needing as much ballast. A much better scenario. This is a tricky area because camber has lots to do with penetration too! So in general from my blue collar perspective of flight performance, (I dont design jets); a thick airfoil with low camber is the worst set up . That is the type of airfoil used on power planes. I suggest that an 8% thick, 1.8% camber is close to the perfect airfoil for thermal/wind flying. Could that be a MH-32? yeap,close. So... What airfoil are you using??? Is it close to that??? Simply put... higher camber airfoils need lots of reflexing to just achieve penetration. Once thermals are located and centered, go to a neutral or slight thermal mode. The MH-32 airfoil is one of the few airfoils of the many i've flown that doesn't really need any camber changing for any thermal/wind conditions. Very user friendly! Saying that... there are much better airfoils of course for speed and pure early morning thermalling. I cant get any more specific than the info above because plane design, ballance point and quality radio installation play a major role in the overall levels of performance.

4) Ahhh... The fun wind challenge? The wind is howling right?? Is it lift or is not? If you know your model very well, and the model is setup like I mentioned above, you'll be able to recognize the model suddenly penetrating, rising, or the tail rising or one half the wing rising. I practice the art of flying my model in heavy winds. I call those straight line winds! The wind of the day. Thermals tend to show themselves when the wind slows down for a short spell depending on the wind speed of the day. Lets call that a thermal cycle. The challenge comes when I first recognize the thermal, positive air, determine if it's straight in front of my model, behind the model, or is the stronger part of the thermal on the left or right side of the model, then I adjust where I'm flying and heading my model. How big is this thermal? Is it big enough and or strong enough to capture and follow it for extended flight times? Is it a genuine thermal? I measure the thermal by a count. The count, in seconds, would be the size and length of the perceived thermal. I count; "one thousand and one... one thousand and two", and so on. A one second count to a one and a half second count is generally not enough thermal size for the size models we're flying. A two to three second count sometimes is all thats needed to core the positive air and gain an advantage in time and win a flight challenge. It takes practice, practice and more practice. I usually stop flying when the winds get to where my plane lands WHEN it wants and WHERE it wants! Short of that I'm flying! Ohhh, theres lots more, just ask. I'd be pleased to answer, as I do lurk the exchange. I only give my input when I'm personally asked.

Otherwise, Thermals to you all,

Richard Burnoski
Chicago S.O.A.R.

-Jeff