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Awful landings - advice requested

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Tony Kenny17/08/2017 20:05:33
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282 forum posts
62 photos

HI All, me again!

I joined SMSA today and flew at Burton Dassett, a beautiful location and friendly club who made me feel very welcome! Lots of lift and some great scenery to boot.

As usually, I ballsed up my landings! If I say what i see and what I think is happening, maybe somebody can suggest something?

I fly a Phoenix 2000, on this slope with the motor disabled and prop tied back.

I tend to kill my airspeed and come in low, maybe 8m above the slope edge and then turn to land. What I find happens is that I shoot way too far back and then either cannot turn at all, or when I turn I have no speed or altitude left to make it back and en up stalling while I struggle to keep airborne - then splat!

So, what I *think* I'm doing wrong. Maybe coming in too slow and low, so that I have no airspeed and hence cannot turn because there's nothing for the control surfaces to push on. When I do turn, maybe I've lost all my airspeed and or course I'm too low to gain any. Any slopes where I'm allowed power, I can throttle up and fight my way back.

My plan, come in higher, although as slow as I dare so I don't end up too far back, and start my turn as soon as I'm over the slope edge, putting crow brakes on just as I complete the turn, or just top brakes, depending on how fast I am, and plenty of down elevator. Then if I don't have enough airspeed, I can trade altitude for speed Sometimes I find the crow gives too much lift and if I'm already slow, then just the "flaps up" type braking kills the lift and helps me get it on the deck.

If I put the crow brakes on too early, are they just going to act as sails and push me too far back again?

Any comments/ suggestions gratefully appreciated. Would be interested to know how far off I am on my assessment.

Tony

Trevor17/08/2017 20:36:38
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365 forum posts
52 photos

Your analysis sounds pretty good to me. Slope landings are all about judging how much energy the aircraft has during the approach. This energy comes from either height or airspeed. You can see the height very clearly but airspeed is altogether more difficult. This problem is exacerbated by the fact that when you turn downwind the model's ground speed increases considerably. This though doesn't contribute to the energy budget. Worse still, on seeing the model screaming off downwind, the temptation is to pull back on the stick to slow it up a bit - hence you find that when you try to turn into wind the model has has a sever energy shortage and you land short.

Practice is the only remedy - but thinking it through as you have done will earn you a greater return on your practice hours.

flight117/08/2017 20:39:23
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609 forum posts
33 photos

Do you have flaps set up on your Ph 2000 if not set up spoilerons ( up ailerons) this will give you control of the lift from the wings so you can descend from a higher point on your landing approach , test a t altitude to see effects on glider and to get to under stand whats going on when deployed.

what you need to do is practice your down wind approach over top of slope and turn into wind for landing. you need to do many a pretend landing at altitude so you can get a feel of it.

A common mistake is to have too low a air speed on the downwind leg resulting in a inability to turn ( as you are near stall) due to the fact your ground speed is fast, this is a bit you need to get used to.

another one is to let the nose of the glider rise on the into wind landing approach , this leads to loss of yaw control and it gets difficult to recover and stay on track , so a rule is to have don't let the nose rise always have to glider with a slight nose down attitude and not nose up from horizontal.

The most important thing is to practice , and if you can try a session with a experienced pilot to talk you through it

I think you are not far off in your assesment but good air speed on dowward leg alows you to turn quickly and where you want, so try not be frightened of it

Tony Kenny17/08/2017 21:13:00
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282 forum posts
62 photos

I have various settings on flaps/brakes as follows and from experimenting at the flat field, this is what I found through lots of practice approaches last week.

1. Crow braking, good for killing airspeed, but with my current set up (99% flap, 54% aileron, 35% down elevator - I mean down as in nose down, not control surface down), generates a lot of lift

2. Flaps, as you'd expect, plenty of lift and drag, better for if I've approached too slow but too low to risk using power for fear of stalling and snapping yet another prop and motor shaft!

3. "Flaps up" style brakes (is that 'air brakes'?), great for killing lift and a bit of speed. When I seem to have my approach just right, but still have oodles of lift, flipping this on pushes her down to mother Earth.

The 'flaps up' version is what I tend to use most at the flat field, only using crow if I think I'm coming in too hot.

But, I've not had time to experiment with these in "unpowered" flying on the slope. I hadn't thought of rehearsing approaches by just coming in really high and going around each time. For that, I might like a spotter to keep an eye on the field.

Is this what you'd expect?

As has been mentioned, because of the wind at 8m/s plus my airspeed, the effective ground speed is pretty fast and I tend to panic as i come off the slope!

Cliff 195917/08/2017 21:19:51
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243 forum posts
54 photos

For what it's worth we tend to land in the lift due to locations, this is done by crabbing in low, may be a couple of feet of the ground, and when you turn into the wind for a second or two you'll be hovering and losing height and, bingo, you're on the ground! Perhaps easier to say than do but if you're too high you just go round again and come in a little lower.

Tony Kenny17/08/2017 21:34:07
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282 forum posts
62 photos

I crabbed it in a couple of times today too mainly because I find it easier but also because I couldn't see the LZ clearly, but I was aware of the rules so felt a little bad doing it. Also, when there are other people on the slope, that is less of an option lest I knock somebody over.

Mark Kettle 118/08/2017 00:28:48
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2343 forum posts
1364 photos

 

Hi Tony, your slope landing problems might be much simpler to fix than you think.

If your done a lot of power flying either electric or i.c flying and started flying slope gliders and soaring this problem can crop up. I'm thinking that you could be flying a landing profile, the approach like you do on a powered model and being caught out down wind with a glider far away without motivate power to work it more forward too where you can see it and want to land often near to where you are standing as you do on a powered field.

The next few paragraphs will explain where the problem may lie, and a different approach to do when flying on a slope as I see it.

When you are at a slope you tend to stand and fly near the edge, this gives you a view of where you want to fly up and down the slope or on the front of the slope. This will be at flying speeds that keep the model in the air and that seem normal, to your eye and senses. You'll be experiencing these as a mix of glider flying airspeed and ground speed.

However as a exercise do a fly by near to your standing position, this will be near the lip or edge and in this area it will have a greater wind speed, this is because the compression of the air close to the edge. This area of slope and the wind speed the effect on your model still provides it with plenty of airspeed for lift, but if measured the flying ground speed would be a little less.

Now because you have the model close to you, your eye and senses should be able to see this and excuse 'the pun' sense this. Now the important thing here, you may have to feed in down elevator to push through this -to stop it ballooning and keep it level - but you should also notice how the 'brakes of ground speed' have been put on.

If the slope your flying as a landing area that is flattish along the top the compression wind isn't there but the wind speed is, it can carry along the slope for quite a long way. Now do a landing approach profile like you do with a powered model where you let it go down wind a little, you'll be trying to land without your eye or senses close 'or' on the model. Down wind the model may be moving and flying however when you turn into wind towards you you'll probably not notice that you have no ground speed when you do this turn far away from you.

So I ask the question? When landing down wind and far away from you, do you land pushing down elevator in or pull up and also how easy is it to keep the wings level. Remember you have no power to bring it closer or to fly on for another go!

So the remedy is, land close to you, if on flying on your own do it near to where you are standing or on a crowded slope moved to the designated landing area. You'll be able to see, sense and control your landing by using the wind near you to land at your feet.

 

 

 

 

 

Edited By Mark Kettle 1 on 18/08/2017 00:30:18

Tom Thomas18/08/2017 02:57:43
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315 forum posts
207 photos

Reading with interest, I may ..... Wind permitting be maidening my gentle lady tomorrow.

Some great advice here, I understand that sloping a 2 channel is a challenge, but I've watched vids of it beng done and it looks fun.

My only experience of sloping was years ago with a Zagi, and landing with one of those doesn't really present a challenge of course because you can't really break it! But I admit to being nervous this time as its a new slope I've found and a new breakable model frown

Piers Bowlan18/08/2017 04:28:52
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1826 forum posts
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You are right Tom, 'wind permitting' is particularly relevant as far as your Gentle Lady is concerned. I would say that 5 to 10 knots is the absolute max for this model. It will soar with the merest hint of lift but it flies slowly so you will struggle to penetrate into wind in a blow. Two channels is not an issue but once you turn into wind to land, getting it down will be a challenge without spoilers or flaps if the wind speed is too high. Good luck with the maiden.

Mark Kettle 118/08/2017 07:00:59
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2343 forum posts
1364 photos

In this nice video a training video by - SpeedsterDEN - from north Denmark it shows how to keep the model close when landing. .

Flaps are not needed to land a glider, however in his video he's using wing flaps mixed with a little down elevator correction. With this setting he slows down the model for some great hand catches.

 

 

 
 
 
 
Below is 'SpeedsterDENs' video description :-
 
How to land your RC slope glider.
As you can see the wind is a bit off the slope and comming from the right, so I start the landing procedure from the left and just let it drift sideway a bit to get in the right possition over the ridge.
In that way you dont need to make a dangerous 360 degree turn in high wind and low height and probberbly stall, or get blown behind the ridge and into the turbolent air.
And when pointing up against the wind, aply and work the flaps or spoilerons and just wait until its down.
For flaps gliders you can dive down, but with spoilerons you have to keep the speed down on the landing speed, if you dive it just accelerate and you will feel that the spoilerons dont work at all, and it will overshoot the landing spot.
If you are on a slope with a turbolent top, then land down in front of the slope, or walk backwards until you can feel a staydy wind, (around 150- 200 feet) and land there.
We do that on a very steep coast slope at the west coast, if you dont do that its 90 % sure that you will crash.
Good luck
S
Glider: Arthobby Thermic 2,5 meter.
East coast, North Denmark.
Flaps vs. spoileron landings:
 

 

Edited By Mark Kettle 1 on 18/08/2017 07:04:07

Speedster18/08/2017 15:15:33
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370 forum posts
163 photos

 

 

How to land your slope glider.

It's very easy if you just do it like this:

smiley

Here the wind is a bit off to the right, so I start the approach from the left, then there is just a bit more head wind, and it's pretty easy to control the glide path.

Here is very turbolent at the dune top, but as you can see I keep the glider up in the clean airflow and stay there, and using the flaps to reduse the speed and height until I can reach it.
If I just fly 5 meter longer downwind or just a bit lower, then it will fly down in the lee and turbolens air and with that groundspeed it will loose all the airspeed and it will stall and dive vertical to the ground.
Wind 12 -14 knots, 
 
More here:
Good luck
Soren

Edited By Speedster on 18/08/2017 15:16:45

Edited By Speedster on 18/08/2017 15:24:58

Edited By Speedster on 18/08/2017 15:33:32

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