Cross WInds

[John Tee]

In his OP Danos mentioned he was flying a glider. I'm not a glider flier but is it not more normal to use rudder as the main control when landing a glider? Also no mention of wheels as others have said when talking I assume about powered models.

John

[PatMc]

John, it doesn't matter whether it's a glider or powered model, if it has ailerons they are normaly the prime directional control throughout the entire flight. If it's an aerobatic glider then rudder would normaly only be used during some aerobatic manouevers. If a thermal glider rudder should be used in a secondary role with ailerons for properly co-ordinated turns but this is difficult to judge from the ground when the model is high so I for one switch in a rudder mix with ailerons of between 30% & 50% during this phase of a flight.

[Simon Chaddock]

Danos

Just remember there is more to the weather than just wind speed.

Some days the wind blows in a lovely smooth stream and in these conditions it is relatively easy to account for it. You quickly feel you have mastered flying in wind.

Another time with apparently less wind the model get thrown about all over the place making accurate flying very difficult and you wonder what's going on.

The answer is of course turbulence. It is not only caused by the air flowing round fixed obstacles but can also be generated (or made much worse) by the atmospheric conditions itself.

I am sure if we could see air flow we would have a much better appreciation of it but we cant so we have to learn by experience.

[fly boy3]

Think I am with Gary here. Eg On landing some feet above the runway near stalling speed the model veers off course. Rudder will yaw it back on course. To use ailerons at this point will roll the model into the ground. That is only if the ailerons will be effective at this speed. Don't want to start an argument here,but that was how I was taught to land many years ago.. Cheers.

[Johnny Kirkham]

On crosswind landings i always us the rudder to keep the nose into wind (as much as possible) whilst just applying a tads of oppersite aileron if and when needed to keep the wings level....then at the last second apply oppersite rudder to bring the nose parallel to the strip.

See how the big boys do it **LINK**

If only i could do it like that......dammit!!!

Johnny

Opps forgot to mention im an IC flyer not a glider man

[Olly P]

Johnny - I have been taught the same flying fullsize gliders, and try to do it on my models. It is very odd when you approach a runway at 45 degrees to land....

[Martin Harris - Moderator]

Posted by Johnny Kirkham on 11/04/2013 01:30:14:

On crosswind landings i always us the rudder to keep the nose into wind (as much as possible) whilst just applying a tads of oppersite aileron if and when needed to keep the wings level....then at the last second apply oppersite rudder to bring the nose parallel to the strip.

Opps forgot to mention im an IC flyer not a glider man

If the wings are kept level the aircraft's nose will not yaw. If you're holding rudder on to keep tracking along the line of the runway then you are also banked and you are side-slipping not crabbing. If you need rudder with power changes i.e. the model's side thrust isn't well designed, then wherever the wind is coming from you'd need to hold in the same amount of rudder on the landing approach.

It's a simple vector triangle - your track through the air offsets the drift over the ground resulting in an approach along the desired runway heading. Just like any aircraft does when flying cross country between two points and they don't need rudder holding in (other than to balance propeller effects).

I'd say that the only time you want to be doing rudder turns is when you're close enough to the ground for a wing drop to be inconsequential - i.e. within a foot or so (in models) from the point the wheels contact and then just to kick off drift.

The key thing is to fly with sufficient airspeed to give good control responses and a margin above the stall to account for turbulence.  This basically means coming in faster in windy conditions. As BEB will tell you, this means either trimming or holding in a bit more down elevator for a smaller angle of attack - not adding more power...

Edited By Martin Harris on 11/04/2013 10:38:11

[will -0]

Johnny, in the link you give showing the airliner, the pilot will certainly not be holding any rudder into wind. The angle you see to the runway is simply that the aircraft is pointing slightly to one side to compensate for the crosswind. It will have got into that attitude by steering in the normal way with ailerons, the rudder will be neutral, the apparent wind from the aircrafts point of view will be directly nose on and only at the last minute will the rudder be used to line the wheels up with the runway. They don'y use the rudder to keep the nose into wind.

Olly i'd be amazed if you're taught to fly with controls crossed on a crosswind approach in a glider. You'll certiainly fly a crabbed approach to allow for the crosswind, but unless you're flying a sideslipped aproach the yaw string will be in the middle. If, of course you're flyying a sideslipped approach in a crosswind, you would normally do it with rudder away from the wind so that you're flying with fuselage aligned to the runway.

[Martin Harris - Moderator]

Posted by will -0 on 11/04/2013 10:37:08:

Johnny, in the link you give showing the airliner, the pilot will certainly not be holding any rudder into wind.

Watching the rudder in the video actually illustrates this very well! It's only applied at the point of touchdown.

Edited By Martin Harris on 11/04/2013 10:44:47

[Olly P]

Will - exactly using the rudder at the last minute to 'straighten out' with respect to the runway.

Hench the comment about it feeling very odd - you think you are going the wrong way visually, but in terms of wind/ground directions you are of course bang on.

Olly

[will -0]

Posted by Martin Harris on 11/04/2013 10:43:49:

Watching the rudder in the video actually illustrates this very well! It's only applied at the point of touchdown.

Edited By Martin Harris on 11/04/2013 10:44:47

And even then only sometimes do they correct the drift before toughdown. Many airliners can land with considerable sideways drift as using the rudder will cause roll which is undesirable in airliners as the engines hang very low and too much bank angle at touch down can cause the engines to strike the runway. FWIW in model terms this is what you have to do with three channel models as you can't use the rudder without the aircraft rolling so the only option is to land with the drift still there.

[Steve Hargreaves - Moderator]

An interesting debate to be sure.....I think we are in danger of confusing two issue here....controlling the approach in a cross wind AND picking up a low wing just before landing......

In a cross wind approach you would point the nose into the wind slightly if you can & then align the fuselage with the runway just before touchdown. The control for this is surely the rudder since this controls the directon in which the nose is pointing. I don't think anyone is suggesting that the rudder control be "held in"...it is applied monentarily to point the aircraft in the right direction. So to recap....a momentary application of rudder to point the nose into wind slightly on approach....a momentary application of opposite rudder to align the fuselage with the direction of travel down the runway.....

Now picking up a low wing on landing.....my understanding is that a downgoing aileron increases the AoA which will make a stall more likely. So if one wing drops slightly during the final approach (& I mean during the flare when you are by definition close to stalling anyway) the safest way to pick the wing up is with a quick stab of rudder which will yaw/roll the aircraft level again.

I should add that this is all highly theoretical to me....with my piloting skills just getting the model down in one piece ranks as an achievement....

[Martin Harris - Moderator]

Absolutely agree - wing drop, first action is opposite rudder. Relatively easy to train your reaction in full size but I've found it somehow less instinctive with a model.

However, I can't agree with your statement that "I don't think anyone is suggesting that the rudder control be "held in"..."

Some people have been advocating holding rudder in e.g. "On crosswind landings i always us the rudder to keep the nose into wind (as much as possible)" , "The trick with landing with a cross wind is to use RUDDER as the primery control" and one person even said "When landing cross wind of couse we apply some rudder to keep the nose pointing slightly into wind until just before touchdown"...!!!

[Steve Hargreaves - Moderator]

Ooo Martin you are naughty..... That last quote was from my post of course & reading it back I can see how it would be interpreted as holding the rudder in continuously but this was not my meaning. Probably better written as "using the rudder keep the nose pointing into wind" the inferance being that the rudder is used as & when necessary........

So easy to get lost in semantics isn't it....

[Martin Harris - Moderator]

I was being a bit ish Steve. From your posts, I realise that we both have the same general understanding of the subject.

Your penultimate post highlighted the two separate facets of the discussion very clearly which should certainly help people understand the subject more easily.

[will -0]

Posted by Martin Harris on 11/04/2013 11:47:22:

Absolutely agree - wing drop, first action is opposite rudder. Relatively easy to train your reaction in full size but I've found it somehow less instinctive with a model.

Mmmmph well I think the first action if a wing drops is to unstall the wing with a dab of forward stick. If you are flying an aircraft with dihedral, using right rudder if the left wing drops will only increase the angle of attack of the dropped wing and make the situation worse.

Granted if you're really low, it's quite hard to unstall the wing without diving into the ground.

[Martin Harris - Moderator]

I thought about that as I was posting and decided that as it was more about a wing drop in the flare that mention of elevator wouldn't be appropriate. If any height is available then I quite agree but opposite rudder is the first action - especially in a standard spin recovery with a pause before applying elevator until the spin stops.

[will -0]

Well then you're getting into the difference between an incipient spin (stall with a wing drop) and a fully developed spin. Usually in an incipient spin, standard stall recovery is sufficient to prevent a spin developing.

[Martin Harris - Moderator]

I was trying to avoid that!

[Hogster]

I wish I knew what you guys were on about At the beggining of the thread I was following it now I'm baffled (easily done I know) Are you describing slide slipping during a landing approach?

[Simon Chaddock]

This thread is in the 'Beginners' section.

I would have to agree with Hogster there is a real danger that these posts might appear very confusing to a beginner trying to understand the principles of a cross wind landing.

[Steve Hargreaves - Moderator]

Its a fair point Simon.....I think the OP has been answered to the posters satisfaction then we wondered off in a slightly different direction....as we so often do.....I can create a new thread for the more technical aspects & move the later posts over......

What does everyone think?

[Hogster]

Sounds good to me Steve

[Danos]

Thanks simon that is what i needed to hear...Turbulance that would explain why i was baffled that i could fly great in strong winds one day but then in minor wind speed the next day i was havin problems but couldnt figure out why. Again thanks to you all ive got some great pointers for flying landings weather etc Cheers guys

Dan

[Danos]

Hi guys me again not sure if any of you are still interested but i took her out for a flight with no wind no crosswind nothing. I was very high up when i ecxperienced the same problem as mentioned in my original post this time i nearly lost her as she dropped altiude behind a massive row of huge huge trees separted by a canal luckily got her back down in one piece. SO i stripped her down completely and found the culprit. ! loose servo wire held on by one strand to the little circuit board inside the servo i asume this wasnt allowing enuff power thru to the servo. I actually managed to witness it while held in my hand when i banked right full power to servo but when i banked left aleron didnt move just jittered but when i waggled stick hard aleron wu dmove very slowly. took servo apart soldered the wire job done..well i hope so anyways :D

P.s I had tested servos rigoulsy but whenever the glider was in my hand all servos acted normal for some annoying reason.