Slowing down (a sports-aero) on landings - flaperons or spoilerons?

[Jonathan M]

So just got back from an evening session. Landings much better now: coming round a bit lower on the base-leg and, after lining-up, getting better at holding the nose up and using the throttle to control descent, then final flare with the throttle off and a reasonable roll-out.

Also practiced using the rudder with a bit of opposite aileron at height on cross-wind legs to get a better feel of the combination. Not so much on landings as the wind was only slightly off the runway line this evening, and I'm not ready to overload things especially as there was some turbulence at low level. Getting more comfortable with it however, and confident it will improve with practice!

---

What I really need is some regular intermediate skills tuition - i.e. an experienced voice by my side directing me through manoeuvres and techniques as I'm flying - but my club lacks readily-available instructors. Doing it on my own is feasible but not optimum, and I've got to be disciplined in deciding what I'm going to practice before each flight, which adds to the work-load. Grabbing the rare weather-window at the end of a working day is all fine and good, but after the second Lipo in succession I begin to tire mentally, so the third and fourth flights tend to get a bit more raggedy.

Sunday morning weather looking hopeful!

[Jon H]

i dont want to get too far down the rabbit hole as its a whole other topic but as i have already mentioned rudder use is a vital skill and the idea of leaving it until after the A cert is not something i would agree with. Stephen pretty much sums up my view as you have to learn all over again and old habits die hard. Its a far better bet to learn it early.

As i fly/teach mode 2 flying i first teach the right stick only so as not to overload the student. Then we bring throttle into the mix, and then rudder. I wouldnt begin to teach landing and takeoff until they can do good circuits flying rudder only with the ailerons disabled.

As a side note, i disable the ailerons for a few reasons. One, it teaches rudder control, but it also gives them an experience to fall back on in the case of aileron servo failure, forgetting to plug them in, or aileron reversal. In these cases you can abandon the ailerons and still control the model.

Rudder mixing on the radio is also a bad idea and my flying this evening after work was a case in point. 12-15mph at least and at about 60-80 degrees off runway heading. My hangar 9 pulse 125 and i had a most enjoyable time practising cross wind landings and cross wind loops. In both cases, rudder and ailerons were in opposition and this is not possible if you mix them on the radio and i deliberately flew this evening just to practise my cross wind landings as i was unhappy with my efforts at the weekend. Cross wind loops to this degree were a new experience and also rather fun.

Jonathan, i am not sure of your skill level as i have never seen you fly but if you want to really test yourself a simple loop can provide quite the challenge...at least it can if you do 20 of them back to back without drifting up/down wind and maintain a position at a fixed distance in front of you and with respect to a reference point on the horizon. Its a really good way of perfecting the use of all 4 primary controls to counter the natural drift of the model in the wind and its tendency to skew out of line due to torque or wind or whatever. Your wot4 is not going to be the best handling model when rudder only but give that a go as well. Go easy at first. Another fun one is to land semi knife edge. Roll the wings about 10 degrees and balance with rudder to keep straight. Get it right and you can touch down on one wheel only and then 'wheelie' down the runway. Piper cubs are good for this in my experience.

I could go on forever about this stuff. After at least 25 years continuous flying i still learn new things every time.

[cymaz]

A good landing starts with a good approach starts with a good circuit. It’s all down to practice. I still make a dog’s dinner out of it.

BTW, if you find yourself at the flying site on a calm evening, I thoroughly recommend do touch and goes for an hour or so. Really concentrates the mind

Edited By cymaz on 06/06/2019 22:43:06

[Jonathan M]

Jon, I wish I'd started flying twenty years before I did (5yrs ago)!

My flying is okay, probably mid-way between A and B Cert levels. But I've tended to have large gaps due to work, family stuff, the distraction of also doing FF scale, and - earlier in the year - the loss of both my previous power models due to TX failure.

EG: I can now often do two consecutive upwind rolls with blips of down/up, each one about 1.5-2 secs, and sometimes get the crossover point properly in front of the pilot-box; downwind still one roll only; loops are big and usually passable, and I'm okay with correcting any mis-alignment on the way round but only with aileron rather than correcting drift with rudder; fig-8's are quite good unless I'm getting tired, stall-turns are mostly fine but have not yet factored in the quarter-rolls on the way up and then down; spins are rubbish because I haven't yet got a feel for how much aileron to add to rudder to get it going properly but not too much, etc, etc.

Sometimes I just 'switch off' and go up and down the flight-line doing half-cubans at each end, sometimes I do the whole upwind leg inverted, sometimes I stall-turn at the upwind end - as if I'm flying my Middle Phase across the slope in ideal conditions!

I'm sure - to mangle the words of Gary Player - I'll get luckier if I practice more!

[Jonathan M]

Posted by cymaz on 06/06/2019 22:41:36:

A good landing starts with a good approach starts with a good circuit. It’s all down to practice...

Absolutely. Whenever I really muck something up, I make myself complete a full proper circuit before trying it again - settles the mind and buys time.

[cymaz]

I often practice flying a straight level line in front of me with a 1/2 Cuban turn around at each end. Excellent practice with some cross wind, you need to “feed “ in rudder on the turn arounds and not ailerons. Rudder keeps the plane on track, using ailerons will just make it screw off in all directions.

[Martin Harris - Moderator]

Posted by alex nicol on 06/06/2019 20:19:23:

For what it's worth, the way I see it is if you got a rudder then learn to use it. We've all had to handle the weather vain effect caused by crosswind landings, the crab approach and that final bit of corrective rudder before flairing out and touching down looks so much neater.

Very satisfying when you get it right, as is the wing low approach with a one wheel landing which I particularly enjoy attempting with my Piper Cub but I have yet to experience a weather vane effect - at least from the moment my model stops being a land based vehicle. It's a figment of the pilot's imagination, I'm afraid!

In order to be affected by the wind, there has to be a connection with a fixed object - that's how your weather vane works but the model is flying in a block of air and is totally unaware of the wind direction. You, as the ground based pilot are aware that it is tracking over the ground differently as it changes direction and problems happen when you make unnecessary corrections based on this optical effect.

In my opinion, the only place for unbalanced flight in the circuit is when you are side slipping deliberately, either to lose height or performing a wing low crosswind approach and that last second correction for a crabbed approach. I see no reason to make flat turns at any other point - even on the approach if a directional correction is being made.

Edited By Martin Harris on 06/06/2019 23:31:20

[Jonathan M]

Good post Martin but to be fair on Alex (although he didn't express himself ideally) he's actually saying to do exactly the same thing: crabbed (presumably wing-level) approach with a touch of rudder to straighten wheels just before touch-down.

[Jon H]

Posted by cymaz on 06/06/2019 22:41:36:

A good landing starts with a good approach starts with a good circuit. It’s all down to practice. I still make a dog’s dinner out of it.

BTW, if you find yourself at the flying site on a calm evening, I thoroughly recommend do touch and goes for an hour or so. Really concentrates the mind

Edited By cymaz on 06/06/2019 22:43:06

totally agree. And if you really want to raise the stakes, put a marker of some kind on the runway and try to tuch down near it each time.

In general though Jonathan it sounds as though you are quite proficient and its a case of where to go next. Spinning/snap rolls are easiest if you just throw the sticks to the corners but the spin in the B needs a little more finesse. Quite often though you dont get a choice regarding spin rate as that tends to be governed by the model itself. With the wing stalled your control inputs can do little to speed up/slow down the rate of rotation.

[Frank Skilbeck]

Posted by Ben B on 06/06/2019 15:53:27:

Just thinking of mention of the thread of electric planes- presumably with an electric set-up the only implication of the power of the set-up is that a more powerful set-up is likely to be heavier (bigger battery, bigger motor). There's no "tick-over" as such, no idle speed to adjust, prop is almost irrelevant- the ESC could even be set on brake to add to the drag (though the risk is always broken props on nose-over).

Slightly off topic, but if you have the ESC brake on to stop the prop it creates less drag than a windmilling prop

[will -0]

Hello

Read with interest, and a couple of things, apologies if already covered some posts are quite length

• Use of rudder at low speed is a good way to get into a spin (well it''s how I do it anyway) so the myth of not "banking and yanking" at low level is baloney. Keep everything coordinated and if your model needs rudder with the aileron to make coordinated turns, do that at low level same as you would higher up.
• Don't be afraid to re-trim the elevator to adjust the airspeed for approach. Many models, particularly those designed to fly faster or set up with a pitchy prop (e.g. your 12x8) benefit from re-trimming from "zooming around" speed to "approach" speed. Personally I use flight modes on the EVO9 to do this at the flick of a switch, your transmitter will likely be different. This makes the model have a slower "natural" speed and generally I find it makes life more comfortable to fly in trim. Experiment higher up to find by how much to change it! Don't forget to approach a bit faster when it's gusty or you have wind shear/turbulence due to e.g. high crops round the patch.
• Don't be alarmed that in lighter winds the model has higher groundspeed. This is normal as it's the airspeed that matters. The effect is that it foreshortens the patch and you have to be a bit more accurate with your approach. Not usually a problem with a Wot4, but sometimes challenging with something a bit heavier and slipperier.

Personally I learnt to fly on gliders. This surely teaches you about using the Elevator for speed control.

[J D 8]

My Major Mannock demonstrates the weather vane effect very well. On landing , mostly roller type as I keep control for longer, as soon as the tail goes down it turns into wind and there is nothing one can do. I think the smallish rudder is blanked. A three point landing results in the same as soon as the wheels/skid touch if not directly into wind.

[Jon H]

Posted by will -0 on 07/06/2019 13:11:30:

• Use of rudder at low speed is a good way to get into a spin (well it''s how I do it anyway) so the myth of not "banking and yanking" at low level is baloney. Keep everything coordinated and if your model needs rudder with the aileron to make coordinated turns, do that at low level same as you would higher up.

With respect will this statement is not exactly true although i understand your thinking.

Bank and yank at low airspeed is far more dangerous and is much more likely to induce a stall. Stalls come from angle of attack and at low airspeed in level flight your angle of attack is high to keep giving you the required lift. What becomes important is relative angle of attack which is derived from the actual angle of the wing chord line and the speed of the oncoming air. You can also add the motion of the wing too but we dont need that right now.

If you are getting close to your angle of attack limit yanking a bunch of elevator will stall the model. This will be more likely if you are banked steeply as you need more lift to maintain altitude due to the tilted lift vector. Also the outer wing traces a longer path than the inner wing during a turn. As we know this gives the inner wing a lower airspeed and higher relative angle of attack. This begins a stall of the inside wing, which is often corrected with aileron, which further stalls the wing due to the increase of angle of attack caused by the aileron. This creates drag which yaws the aircraft toward the stalled wing, this creates more roll...and then its game over.

To get back to the spin argument a spin is created as the wing stalls by shoving a bunch of rudder in a given direction. We all know this stalls one wing and gives the other added lift as one wing moves forward and one aft. The model then spins as in my example above. The key is the fact that the wing is already on the verge of a stall with very high angle of attack and it needs only a nudge to push it over the edge. With elevator held back angle of attack remains high and the wing remains stalled.

In the case of our landing approach discussion, this stall point should only be reached (ideally anyway) about 2mm off the floor. The model then stalls onto the ground and stays there. This is why i have been suggesting that long/flat approaches with power are a bad idea as you are hanging in this almost stalled condition and any input can be enough to push the wing too far and stall it. I suspect this is what you have seen in the past when models have crashed due to rudder input on approach. They were too slow in the first place and the rudder input prompted a spin. If the model is flown in at a more normal attitude without hanging on the elevators there is no risk of a spin and the rudder inputs i am suggesting here are relatively small. Its a shame i couldnt record my flight the other day in the wind. it would have explained a few things.

Large warbirds are the very vulnerable to stalls and spins. They are heavy, have high wing loading and are quite unforgiving if mishandled. This again is why i do steep approaches with lots of drag on to control the decent, using power as needed to maintain the approach. All the while i dont touch the elevator. Rudder and ailerons are busy keeping things straight but the elevator is left alone. This keeps angle of attack constant and low meaning i am nowhere near a stall. The only thing you have to remember is to add power just as you flare as you are no longer in a dive and all that drag robs your speed very quickly.

As an example, watch the following video's The first shows how fast a warbird scrubs speed with its nose up, the 2nd my effort with the same model (skip to 6mins 10). notice how i am always nose down. No chance of a stall.

I hope this makes sense. I think we are back to square one though as many dont use the rudder enough to use it with the same finesse as the other controls. Its then likely they over control it somewhat and get themselves into trouble.

[will -0]

Jon, couldn't agree more, not stalling is a good way to not spin, however flying in a yawed state is not a good place to be if you're going slowly, and of course one of the issues with banking and yanking as it were is that the load on the wing goes up in a turn and so does the stall "speed".

 

What I am calling out here is the mistaken belief that somehow it is safer to steer using the rudder only rather than doing normal coordinated turns when near the ground or if there is a cross wind or some other tosh. It isn't. Turn like you normally do (and don't stall).

 

One of the challenges that your first video shows is that speed judgement in approach is not easy as it is often head on. This does make it important to be flying in trim, as then the aircraft is going at the correct speed naturally On further point and then I'll shut up -

on the issue of learning to fly gliders - this teaches you that to avoid a stall (and hence spin) you lower the nose by pushing forward on the stick/giving down elevator. You don't do it by opening the throttle. I suspect the LA7 pilot in your video could have had a better outcome if he'd lowered the nose first and opened the throttle second.

Edited By will -0 on 07/06/2019 15:24:10

[Geoff S]

I'm a pretty crap pilot on the whole but I usually (actually, mostly) manage to get my models up and down OK. I agree with the elevator for speed and throttle for altitude technique (though obviously both have an effect the other way round). My method is to regard landing as a low slow(ish) pass and try to fly parallel to the ground until the plane is low enough to shut the throttle enough for the wheels to touch the tarmac (or grass). So a shallow approach at least in the ultimate phase of the approach is the answer.

I'm not great at landing so I make myself do a few touch and goes every flight just for practice (and fun) - it's cured me of the ground fear at least

I offered the idea to a club member who's a much better pilot than I am but was having problems landing a biggish petrol powered P47 without its nosing over. He said it helped. Now all I need to do is put it into practice with my quarter scale Mew Gull before I totally wear out the engine cowl! No such problems with my electric balsa ARTF Wottie though.

Geoff

[Martin Harris - Moderator]

It's all a matter of degree. No-one is recommending hanging nose high on the throttle but using an appropriate amount of power for a controlled descent. If you listen carefully to Jon's lovely approach and landing, at 6.40 you hear the final power reduction in preparation for the flare...

will-o...the often repeated advice to make heading corrections on approach with rudder is exactly what prompted me to post one of my earlier responses.

I certainly can't see how we've arrived at any suggestion of "bank and yank" - simple co-ordinated adjustments are very different to 60 degree banked 2g tight turns!

However, I'm fairly sure we're all in agreement that a simple estimate of when to shut the throttle to idle at some arbitrary height in the circuit followed by a glide approach resulting in the temptation to burn off height with elevator is the root cause of many pilots' embarrassment...and not confined to new pilots by any means!

Knowing your model and what it looks and behaves like around the stall is a prerequisite to a tidy and reliable approach at a safe attitude - after which, the landing is so much easier and safer. The Yak in the first of Jon's videos didn't need an experienced Yak pilot to see that it was dangerously nose high and the tip stall came as little surprise. Many models with effective flaps need a noticeable pitch down balanced by power to maintain a safe and stable approach - again, get used to that safe attitude at height and it will reward you on approach.

[Jon H]

Will, im with you on the flying coordinated argument. If its all out of whack then you are in a bad place for sure. In the case of cross wind landings you really only want the final flare/touchdown to be done, in effect, out of balance and cross controlled.

I think one mistake people make is forgetting that each control acts on a primary axis and should be used to control that axis. Interactions between power/pitch/roll/yaw are obviously there, but each control has one primary function.

My example of this is always twins with an engine out. They loose a motor, the model rolls towards the dead engine and its corrected with aileron. WRONG! the model yawed left, it then rolled as a secondary effect of the yaw. Its the yaw causing the problem so correct it with rudder and not aileron. As i have said before, address the disease not the symptoms. Invariably though the correction is made with aileron, adding more drag to the wing with a dead engine and increasing the yaw angle. Add to this a bank angle in the opposite direction to maintain heading and where are we? oh yes, uncoordinated, wrong side of the drag curve with high angle of attack. Not a nice place to be. assuming you get the yaw sorted out in our hypothetical twin situation you can then tidy up with ailerons as you will have more airflow over the wing with the running engine so it will want to roll a bit, but that is icing on the cake stuff.

Martin, Like you i cant see how anyone could make such an error with a warbird and stall it in from that height. It was obvious it wasnt going to end well, but still its a lawn dart. This isnt a criticism of those people personally as i am looking at it from a position of experience with warbirds and to me the 2-3 seconds he had to think about it was an eternity, to him, on a maiden flight? it was probably on the ground before he even knew he had the accident. I saw this last year when trying to help a proficient pilot move into 80 inch WWII fighters. A few small errors (and they were small) left him in a spin after 2/3 of a circuit with a new model. Panic sets in and its all over. Luckily i was able to grab the tranny and recover the spin, the model was saved, but it was a close shave. He knew he was in a spin, but due to an immense workload he was unable to work out a solution. Being experienced it didnt phase me to th same degree and i was able to work it out, but its not always that easy.

Which brings me to another point. In full size they call them human factors, we could also call them 'deer in the headlights' factors, but know how to do something is no good if your brain has left the building due to panic. People freeze i unexpected situations, or do something random which might make the problem worse. This is why flight planning is so vital, especially on landing. Make each approach the same, start in the same place, turn in the same place, drop gear or flaps in the same sequence, change rates etc and know instinctively where all your switches are. If you do the same thing each time you end up forgetting all about the landing and instead focus on the variables. Where is the wind, is it turbulent today, what happens if i need to go around, if the engine quits/i run out of lipo can i glide it in or am i better in the field.

If you are able to think about these things ahead of time they are less likely to surprise you. If you arent surprised you can still think, if you can think you can enact the plan you already made before you took off. I know its a bit of a cliche, but so much of this is a mind game at the end of it all.

Oh and by the way. None of this is intend to belittle or intimidate anyone. As model pilots we are a diverse bunch with a range of experience, ability and age. Some have natural aptitude, some have to really work for it. If i comment on something someone is doing wrong/can improve its not an ego trip, its because i genuinely think they can improve and it will increase their enjoyment of the hobby. Its not about being the best, its about being as good as you personally can be. If anyone reading all this lot thinks the things discussed here are beyond them or their ability i say no. Try it, do what you can to think it all through and then give it a go as Martin suggested. You might surprise yourself.

[Jon H]

oh my..that was longer than i realised.

[Jonathan M]

Jon, long isn't necessarily bad!

Lots excellent nuggets in there (as in this thread as a whole) especially the stuff about trying to be as good as you can be and never mind anyone else.

For my part (drifting back a bit to where this all started), watching those two videos jolted my memory: I started the nose down business after I'd read an article earlier this year in RCM&E on the correct 'keep-the-speed-up' technique for landing warbirds. Clearly the Wot4 as a sports-aero doesn't fall into the same category and needs its own approach.

One other thing: I unwrapped my new incidence meter and checked the model, which is zero-zero on both the wing and tailplane; elevator trim is about 1.5mm up, which therefore makes sense.

Forecast looking good for Sunday morning... at the moment!

Edited By Jonathan M on 07/06/2019 21:25:20