micro ridge or thermal

[HELModels]

I've been getting some more flight experience with my own design V-tail pusher. I know it is not a traditional glider, uses a freeflight wing, has a CDROM motor, but the thing wants to thermal. So, I figure I better appease her by learning how to thermal and read lift of different varieties.

tonight I went to the field and wind was about 5 knots, fairly steady and no noticeable gusts. I plug in and toss into the wind, weathervanes alittle and I find the true heading. climb up to desired altitude and cut the motor way back to a few clicks above off so there is still alittle power. I keep getting jostled around, wings tipping, nose pitching. Here is where I think I learned something. Plane gets pitched up and approaches stall, so I turn knowing a level turn requires pitch up -turn and nose comes down, stall avoided. I just picked any direction to turn and held it and up she went. This seems like a thermal, but keeps showing up in the same spot. I did notice that upwind of where I was flying is alot of pavement and I was flying in a grassy area. The lift kept showing up along a ridge. I say ridge, but it is probably only 20-30 feet different in elevation from the paved areas. Am I seeing ridge lift or is this thermals being blown by the wind?
I've flown this spot a few nights and the lift always seems in that region whether there is wind or not. I also noticed that higher up the winds were stronger, smoother and if I flew downwind a little further from the "ridge" I could almost hold ground position with same low throttle setting. eventually make it to the ridge and up she went again. Fly away from the lift too much and down she came like rolling down a hill.

Feel free to expound on micro meterology, thermals, or anything related to keeping a small plane airborn without using full power.

[Thermalin]

Your text makes its difficult (for me anyway) to pinpoint what your seeing.. 1) you encounter lift on the ridge area whether wind is blowing or not. 2) Lift always seems to be in that region. 3) It's a bit downwind of what would be thermal generating terrain.

My questions... .what is your own design in terms of size, weight. What is the makeup of the ridge regarding incline (30 degress, 75 degrees?) When you say "wether the wind is blowing or not".. Is it dead calm or does the wind just become much less. What time of evening are you flying.

When thermals leave the ground.. depending on strength, air moves in to fill the area, hence a breeze. (in calm conditions this is easily felt. In a more breezy day.. it becomes more difficult to figure). Its confusing b/c if the thermal producing area is upwind of the ridge.. the "breeze" should be moving in that direction intially anyway. If your flying something very light.. it doesn't take much to gain altitude either via thermal or the small ridge your flying which is seems big enough at 20-30ft in height. You may be experiencing a bit of both .... thermal may be moving toward the ridge and up/over it as it passes causing what I believe some call Slermals. This may explain why you encounter lift when there is no wind (thermal) and lift when there is (slope lift). I know from experience it doesn't take much to slope fly a lightly loaded ship big or small... (just my thoughts.)
Mike

[HELModels]

I went back out tonight and I thought I had experienced no wind before, but this was absolutely dead calm. Other evenings when it was what I thought "no wind" there must have been 1 knot or so. What I found tonight was no lift on the mini ridge or anywhere. Still had a nice flight.

As for what I called a micro ridge, the paved area has a few large buildings and I judge the difference in elevation to be 20-30 feet because I am about eye level with the second floor. The change in elevation from where I fly and the hot spots is pretty gradual 30 feet in 100yards, maybe.

The plane has about 8.0 oz. wing loading and 30" span.

I'll just accept lift as lift wherever I find it, but learning to read it is a goal.

[Thermalin]

30 feet over 100 yards I dont think will do anything for you regarding slope lift but I couild be wrong.... your talking 10 yards vertical over 100 yards in length.. 10% elevation..... now if it was 30 ft in the span of 60ft ..that woiuld be diff... I'm thinking the air is heating over the lot / bldg area.. moves off toward the ridge and the contained heated mass just continues to rise having you think its slope lift. Only thing I can come up with...

I have found thermals to be more like big balloons or series of bubbles... rather than cone like as some pics depict. Fly long enough and you can form a picture in your head of what is happening based on how it telegraphs its movements to you.

I have flown and been pushed away hard... in that case you turn hard in the opposite direction.. this can happen at any altitude. I have flown right through the middle of weak thermals ( the plane ceases to lose altitude and flies tail up) and strong thermals (tail up and violent bobbing and jerking) both times continuing to fly straight... but passing through other side always brings same result.. SINK... in both cases turn in either direction and see which side "most" of the bubble is on and try to center in it.

if only it were that easy!
Mike