Landing Techniques

[cymaz]

A couple of us went off topic ( Wot4 XL engine choices) talking about landing techniques and experiences for biplanes.

Since it is the most risk and critical part of the flight to do well, ( unless you want your prize creation pulped into a mess). I thought it would be an idea to start a thread on how we get around the problem of fighting gravity, wind and speed only a matter of inches from terra firma.

Biplanes need to have some powe on landings. This keeps the wind going over the tail, making the flying surfaces still effective. Trying to get one of these things to glide in is almost impossible. Also bear in mind that the bipe will also want to weather cock into wind so rudder authority becomes vital.

Well I've made a start.......carry on!

Edited By cymaz on 27/04/2017 17:30:42

[flight1]

Basics -- remember use throttle to control decent rate not elevator , and remember that the air speed of the the plane is the important bit not how fast you are traveling over the ground.

also to far forward c.of.g makes landing harder and 'flaring out' with elevator having a delaide response.

there we go Pete started

[Frank Skilbeck]

My Wots Wot deadsticks quite well

[Martin Harris - Moderator]

As does my Panic. My Pitts Special would dead stick OK (until a dead stick over the woods downwind of the only landable area) but with around a 1:1 glide angle!

Good advice above but it won't weathercock (until the wheels touch)...drift, yes, but perhaps adverse yaw at lower airspeed while correcting the approach path gives that impression? You're quite right about the need for good rudder control though, as uncoordinated flight adds even more drag!

Edited By Martin Harris on 27/04/2017 18:12:53

[Former Member]

[This posting has been removed]

[Geoff S]

We often have to land over a berm at the end of our tarmac (put there in an attempt to keep motorcycles off, I think) and people tend to misjudge its height/position and 'land' the wrong side. A technique I use (often successfully though not always) is one I read in one of the mags, perhaps RCME, some years ago. That is to pick an arbitrary horizon and keep the model at the same height above it using the throttle mainly, but elevator for speed control, to keep it constant and the model should reach short finals perfectly and safely above local obstructions. Then it's just a matter of flare and throttle reduction. I try to think of landing as trying for a very low pass parallel to the ground before closing the throttle for the final touch down.

In our case once the model starts to lose height as it approaches the berm you'll hit it unless last minute action is taken.

I would add that I'm rubbish at landing and therefore do at least one practice touch and go every flight in an attempt to improve

Geoff

[Former Member]

[This posting has been removed]

[Peter Christy]

Some years ago, I had one of the Phil Ramsey Pitts Specials. It required at least 35% throttle on the approach to stay in the air! As soon as you cut the power, it would fall out of the sky like a sack of potatoes.

Our club had Brian Lecomber around as a guest speaker around that time, well known as "Mr. Pitts" in full-size circles. During the break, I commented on this to him. He replied, "Its very close to scale then! The full size is just the same!"

--

Pete

[Don Fry]

I find with multiwings is not to overpower them. The likes of Panics I have no experience of, but often tempted, but I imagine you plant them in. But put a triplane down, a DR VII, and excess power is your enemy. Tickle the throttle as much as you like, but there is little margins between draggy brick and too fast for the spindly undercarriage.

I am a petrol head. Lecci users read sort the prop to suit the plane.

[David Davis]

At my club we are lucky enough to have a tarmac runway. Trouble is, it's only ten metres wide and at my previous club I had at least a fifty metre grass square to land on. Initially my landings were all over the place; the model frequently landed on the adjacent grass strip and ripped off the undercarriage which was secured with nylon bolts. The club's best pilot must have felt sorry for me and walked me out to the centre of the strip. We stood astride the white lines and he told me that if I lined my model up with a dead tree in one direction and a pair of mature spruces in the opposite direction when on finals the model was sure to land in the middle of the runway. I don't always get it right now but my landings have improved.

The picture shows the landing strip looking west towards the dead tree which is the tallest blob on the horizon! Sorry about the picture quality, photography was my father's forte, and my great grandfather's, not mine.

[eflightray]

Start well out so you don't have to dive for the runway, make sure you find the gap in the trees, , easy.

Ray.

[cymaz]

My instructor always said," a good landing starts with a good approach".

A good approach starts with a good circuit. So, who gives up doing rectangle circuit practice as soon as they've passed the " A" test? Also practice touch and go circuits. It's great fun if two or three of you do it together.....it makes sure you don't fluff your T & G up.

[Keith Simmons]

You can't have a good landing after a bad approach. So get each step right at a time and concentrate on that. Don't think of the end landing result yet but focus on entering the downwind leg at the right height and speed, turn, base leg, turn and finals or final leg and then land. Some do downwind leg and turn to finals and don't forget the wind gradient as you land as the wind tapers down to the ground.

[Bill_B]

Posted by cymaz on 27/04/2017 20:13:22:

My instructor always said," a good landing starts with a good approach".

A good approach starts with a good circuit. So, who gives up doing rectangle circuit practice as soon as they've passed the " A" test? Also practice touch and go circuits. It's great fun if two or three of you do it together.....it makes sure you don't fluff your T & G up.

Rectangle circuit? Fine in theory, but not always necessary, desirable or even possible depending on the weather conditions and/or topography of the site. When slope soaring or flat field gliding, you soon learn to keep your options open and improvise if necessary.

[Bill_B]

Posted by Keith Simmons on 27/04/2017 20:31:32:

You can't have a good landing after a bad approach.

I beg to differ.

[ChrisB]

Rectangular landing approaches don't really work very well. I find a curved approach is far better. The theory of a rectangular approach is all fine and lovely but its very difficult to do a 90 degree turn, as this bleeds speed and requires a lot of control input, the last thing you want to be doing on a landing approach with slowing airspeed.

Generally the larger and heavier the model, the more throttle you'll need. My Topflite 1/5th P47 descends rapidly at idle, it needs some throttle to arrest the descent, the same with my dads 30% Cessna, you need to tickle the throttle down, click by click until touch down and then drop to idle.

[Geoff S]

Posted by eflightray on 27/04/2017 19:21:35:

Start well out so you don't have to dive for the runway, make sure you find the gap in the trees, , easy.

Ray.

Actually Ray's video shows my constant height above the horizon technique perfectly. The model is at a constant height above the horizon right until it is virtually down on the intended landing area and in no danger from obstructions.

Geoff

[J D 8]

Like ChrisB I prefer the curved approach,by stretching or shrinking the curve some I find I can arrive at my chosen touchdown point without changing throttle setting most of the time.

[Martin Harris - Moderator]

I find my most satisfying approaches are the straight in ones where everything feels locked in and the model feels as if it's only responding in the vertical plane to my throttle inputs...not sure if this describes what it's meant to but I know what I mean! Especially if it's in conjunction with a nice wing low crosswind approach!

There are two situations where I'll fly curved approaches, dead sticks and scale where appropriate (e.g. Spitfire). However, I was at Old Warden last week and noticed that the Hurricane came in on a long straight approach - and then read a contemporary account from an old BoB pilot which mentioned the good visibility over the nose on approach so that's one off my list of curved approaches!

In fact, I try to teach people to get on a straight approach which, for a model pilot, means going past the apparent turning point...turning sooner actually requires constant heading changes to avoid landing further out than you intended with the model being angled towards the flight line. Especially for novices, these corrections usually introduce unwanted secondary effects and make the job harder. Flown on the runway heading, it actually appears to point slightly away from the pilots as it gets closer.

[Peter Jenkins]

Even before a good approach I would always suggest a well trimmed model. In particular, make sure that the thrust line is sorted so that increasing power doesn't cause an immediate nose up (or down for that matter) pitch. It's worth sorting this out before you start the issue of setting up a landing.

I think most of the points have already been made above but here's my take.

I think a rectangular circuit work very well provided there are no issues with infringing no fly zones or trees/other obstacles. The cross wind leg allows the throttle to be reduced to establish a descent which you can eyeball more easily than during a curved approach unless you are an experienced pilot. Avoid getting into the situation where you just close the throttle to idle and glide in - that gives you no control if you are going to overshoot. Therefore, avoid flying the circuit too high.

The value of a physical aiming point for the final turn is very helpful when lining up to land as you can control your landing position more accurately - very helpful when the strip is narrow. The final turn should not be too steep, 30 deg of bank is sufficient and you can vary the bank angle to adjust the radius of turn. This avoids the tendency for the model to drop its nose significantly. If you have to bank past 45 degrees to line up with the runway then you didn't start your turn early enough - overshoot and try again by starting the turn earlier. You can add a click or so of engine power as you apply a tad more elevator to maintain the constant descent rate during the turn. A shallow turn means that you are less likely to have the speed bleed away quickly and thus lead to an incipient spin.

Depending on the direction of the cross wind, roll out from your final turn with the nose pointing sufficiently into the direction from which the crosswind is blowing so that the ground track is correct to make the desired landing point. Use throttle to control the rate of descent and the elevator to control the attitude/speed - the cross wind leg will have allowed you to set the desired descent attitude which should be maintained up to the point that you need to flare for landing. As you start the flare, gently reduce the power to idle and stretch the glide as much as possible aiming to have lost most of the flying speed before you touch down.

If you are landing in a cross wind, as you start the flare apply rudder gently in the direction away from the wind - i.e. if you are approaching from the right with the wind blowing into your face you will need left rudder and vice versa. Be prepared to add a touch of opposite aileron to keep the wings level and better still aim to have the model banked slightly into the cross wind.

If you have a flap equipped aircraft remember that with the flaps down the aileron effectiveness is reduced as you have shifted the centre of pressure inboard due to the greater lift from the part of the wing which the flaps are affecting.

As in full size aviation, the most difficult thing to achieve is the perfect landing circuit. Fortunately, practice makes perfect though.

[Former Member]

[This posting has been removed]

[David Davis]

Posted by Tom Sharp 2 on 28/04/2017 01:08:42:

where I fly there is a pilots box 10 meters back from the runway. You take off and land standing in the box so no standing in the middle of the runway to line up your model.

Same at my club. When the club's president and I stood in the middle of the runway it was so that he could show me the aiming points, the dead tree in one direction and the two fir trees in the other. Line up the tail of your model with either of these landmarks, depending on wind direction, and you will land in the middle of the runway. The pilots stand a fair way from the runway especially as we have a high proportion of novices in our club.

[cymaz]

Posted by David Davis on 28/04/2017 03:54:46:

Posted by Tom Sharp 2 on 28/04/2017 01:08:42:

where I fly there is a pilots box 10 meters back from the runway. You take off and land standing in the box so no standing in the middle of the runway to line up your model.

Same at my club. When the club's president and I stood in the middle of the runway it was so that he could show me the aiming points, the dead tree in one direction and the two fir trees in the other. Line up the tail of your model with either of these landmarks, depending on wind direction, and you will land in the middle of the runway. The pilots stand a fair way from the runway especially as we have a high proportion of novices in our club.

Good point. The bmfa have changed things a bit for the A . You now must be on the pilots box for take off. Whereas the old test you were allowed on the strip. At are club there are markers I line up with up with to get the approach line correct. Not so easy when you visit another club! I also make the call " low circuit then landing" . I just do a low- ish pass to see how the wind is, after the pass I call or the landing.

We also have two wind socks. One tall one by the club hut away from trees. The second is a couple of meters high at the end of the runway. It's surprising how they differ sometimes, affected by trees and wind gradient.

 

Edited By cymaz on 28/04/2017 05:22:14

[David Davis]

Despite having first learned to fly r/c in the late 1980s, and despite being a club-level instructor, my landings are still my weakest suit. I wrecked two beautiful kit built Acro Wots powered by 61 two-strokes through landing too quickly on grass.The undercarriages ripped off taking taking the fuselage former with them which allowed the wing to break away. I gave both of the wrecks to a friend who said he would repair them. He hasn't! My fault as I had previously landed both models successfully and had observed that they still flew well even at slow speed on finals. Sometimes however, I over-compensate, approach too slowly and stall!

I know all about using the throttle to gain or lose height and the elevator to regulate speed while landing but if you are on finals with the model descending and you want to slow it down, you apply up elevator, surely the model will then climb and you will have to lose the height you've gained by further reducing the throttle. Is that right?

Any advice from the cognoscenti will be gratefully appreciated.

[Don Fry]

David, on the crosswind leg before the final turn, put a fixed ammount of up elevator in. How much is worked out in advance at a safe height. It's not too far from the stall, but comfortable above it. Tip stallers a bit faster. This gives you a base speed, a bit nose up, and a bit more drag.

Keep that up input nailed. You move your thumb side to side, not up and down from now on. And then all you do is steer it, and alter height with the throttle. You only alter the up input to flare out on touchdown. And remove it entirely at touchdown, to minimise bouncing.

Some do a transmitter mix to input the up elevator. But not wise if the landing has to be aborted in a hurry.

Mind, I only know how to do it. Doing it ain't so easy, but this way gives a structure to the job.

Edited By Donald Fry on 28/04/2017 07:46:13