I have seen mention that some people prefer to use less flap when landing with strong winds.

What is the thinking behind this and what benefits are those that prescribe to this attempting to achieve?

I always reduce my flaps in strong winds. Wind on the nose is free airspeed and my plane will float if I don't and make it hard to land and make stay on the ground if I don't.

Sicklick, I think it is a very situational question and it really depends on the plane...My BVM Hun gets Full Flap + Speed brake treatment on every run! Just landed her in a 20+ head wind. I was at 2/3 throttle until I hit the numbers and landed on a 650 runway at Warbirds Over Denver with no problem.

'Pends on the plane. My Skymaster MB339 conversely doesn't sink like the Hun, instead she gets too floatie in strong winds with half flaps only. However even though the two planes are more different that nigh and day, again with the MB339 I also drop full flaps to +60 degrees and give her crow too. Landed her in 20+ headwinds this weekend too with no issues. My large BVM F86 has Fowlers, you NEED to drop full flaps and air brake for a steady reliable approach and descent.

I don't know...maybe the answer is just as much a function of how each person flies AS WELL as the type of jet...
Happy landings bud,

Shaz

In full size it is common to use less as the winds increase. But the main issue there is if you have a turbulent crosswind component in high winds .. then roll response will be critical. The benefit of the lowered stall speed that comes with flaps, is counter to the lack of roll response at those airspeeds.

The first stage of flap increases lift a lot and drag a bit. Landing flap adds a lot of drag and a little more lift. If you're suffering from 'floating' in high winds do you not need more flap (not less)?

Aileron response is improved by increased airspeed and this can still be achieved with full flap. I don't know of any full size aircraft that use part flap for landing in strong winds (although I concede that there may be some). The benefit of the 'free airspeed' is usually considered to be a lower ground speed on landing rather than the option to use less flap.

I can understand that there may some issues with our perception due to the fact that we may find it more difficult to judge our approach speed from outside the model than a full size pilot would when sitting in it but, from an aerodynamic point of view, I still lean towards using full flap no matter what the wind speed is.

I'm not criticising anyone for doing anything different and if it works for you then great (a bit like the crow/no crow argument).

I agree,

I land full flaps no matter the wind. I don't land based on what I think the airspeed is, but by knowing my sink rate at a certain throttle. If I don't use full flaps as always, then i can't judge my sink rate as I'm used to.

If it is windy, just account for that as you turn from your downwind to your base, so you make a much shorter approach.

But then again, it is a matter of how you feel confortable. I know that there are some that prefer to use 1/2 flaps and land at a higher ground speed. In my case, it just takes my outside my known flight envelope for landing

I found out the hard way that half flap landing in high gusty winds can be fatal, due to the extra lift generated it is all too easy to get into a porpoise situation.
Since then I use full flap and airbrakes if available in any conditions and have had zero problems. Just need extra power as mentioned earlier.

For me & what I fly half flap is for extra lift & only used for take off.


Full flap, (about 80 degrees) is all about drag & speed control, more
wind just means more power used on the approach or, alternatively,
a steeper approach. I always use full flap for landing & sometimes this
requires quite high power setting on the approach..

Given the choice, if I was caught in wind that suddenly turned to a gale
while flying, I would land with no flap at all. - John.

Full size aircraft do not fly the approach on sink rate. They fly at a specific standard approach angle (glideslope) of 3 degrees (with very occasional local variation). In a strong headwind that means you need more power on the approach. The sink rate is less, since the ground speed is less in a headwind, to maintain the 3 degree slope.

Some aircraft I have flown, for example the twin turboprops HS 748 and B.Ae. ATP, use one notch of flap less in a strong wind. Stopping in a headwind is not a problem, but strong winds are usually gusty so the airspeed jumps around in the gusts. The flap limiting speed is appreciably higher with the lesser flap angle so it is easier to keep the erratic airspeed above stalling speed and below flap limiting speed. As has been pointed out already, aileroncontrol is more positive at the higher airspeed. The purpose of the drag flap setting is to increase the power setting on approach so that theturbineenginesare more responsive, they spool up quicker on go-around. But we have increased power anyway, for the headwind, so we don't need the extra drag.

The last stage of flap provides pure drag with very little lift augmentation. Most of the big jets (I've flown 747, 757 & 767) land with full flap even in strong winds. I can't remember back as far as L1011 and HS Trident. My last aircraft before retirement were the 757/767 and they used less flap (20 instead of 27) for engine-out (assymetric) landings, because they didn't need the extra drag from 27 flap.

When flying model jets I generally use a lesser flap setting in a strong wind, but recently I was using full land flap in a strong wind, and practising my X-wind technique with my O/D jet trainer JayTee.

The reasoning behind less flaps in windy conditions is

1) you don't need all the extra drag (there is little or no extra lift to be had between a typical half flap and full flap setting, just extra drag) to set up a reasonable glide path angle while still keeping some power on for a potential go-around.

2) a bit of extra speed adds more controllability for handling the gusts and turbulence.

Like stated in previous posts, just use more throttle in windy conditions on normal landings.


Only reduce flap or even don´t use them if you have a emergency situation (no engine) in windy conditions for stretching the glide to the runway.

I understand that on fullsize, you have data. But on the model, the sink rate is very easy to judge from the ground, so for me is a good measure. The way I land is: I know the angle of attack my plane likes (this usually means, never look at the top of the wings, only bottom), I know the throttle setting and I judge the sinkrate. Sinkrate too low, lower the throttle a tiny bit. Sinkrate to high, add throttle and maybe drop the nose for a sec. None of this "judgement" is affected by observed groundspeed (since we don't really know the airspeed), so I try to always keep it constant, by always landing full flap, regardless of the wind.

Also, what you mention about turbulence on high winds makes sense, but again, I don't like changing the behavior of my plane on landings by having different flaps settings

Again, techniques are very personal. This one works for me, but I'm sure there other ways

Jack

Alasdair gave a great description of flap use in air carriers, we are very concerned there about "overspeeding" the flaps with strong gusty winds. But all planes are different, the older model 737's handled strong winds fine with full flaps. The newer models like the -700 move around much more with full flaps in gusty winds. (That said if you need full flaps for runway stopping margin, then you use them and "stir the stick" a bit more!) So when I got my BVM Electra and the manual said to reduce flaps deflection from 2.5" to 2" in high winds (over 15mph), that sounded right to me. But after 100+ flights I do not vary my flaps settings for landing anymore as I just left it at 2". The Electra lands slowly even at that setting.
Concerning RC planes, I have seen JackD do a lot of landings with his Electra and a lot of other BVM turbine jets. He is a master at setting those planes down (I am not!) and what he said makes perfect sense. I would take his advice. I know in my case I have trouble when I "drag it in" on a shallow approach, or flare to far instead of flying the model onto the ground, in both cases getting too slow to have really precise control of the model. That is a perception problem, not a flap problem!

Bob Violet recommends reduced flap settings in high wind on his F-86 80" Sabre.

Andy I got the same manual that you do, but I ain't planning on flying in much more than 20 mph winds, and in 20 mph full flaps and air brakes are perfect. I'm no sayin, I'm just sayin.

Shaz

Like Jack I always do the same thing all the time wind or no wind. My BVM F100 full flaps, speed brake. BVM P80, Full flap, speed brake and crow. BVM Bandit Full flap and crow. The only thing that changes with wind is the power setting. Shzam stated the BV recomends less flap in high wind. Their are a lot of planes out their with a light wing load. I have seen many strugle to get them on the ground. Crow is the key on helping the problem also make sure the elevator is not to sensitive. One more thing I do is have speed brake and crow automaticly come on when I go to full flap. Less switchs to think about. I use no duel rates also to give it the KISS system. Dan Avilla

The purpose of flaps is to increase lift and drag. At lesser deflections, they mainly increase lift. As you increase flap deflection, lift increases but so does drag. Beyond a certain point, any additional deflection just adds more drag.

You want more lift for one purpose, to be able to fly slower, and thereby land at a slower speed, which means a shorter landing roll. Very important for jet airliners and jet fighters.

You want more drag for two reasons: First, to increase your angle of descent. This enables you to fly a steeper approach while maintaining a given airspeed. Second, to require more thrust on approach. This reduces spool-up time in the even of a missed approach.

So why would you want less flap in windy or gusty conditions? Actually you really don't, unless you are using a very high drag flap setting. Airbus A320's and Boeing 757's use the same flap setting no matter what. What they do change; however, is approach speed in gusty wind conditions. The same applies to model jets. In gusty wind conditions what you need is a higher approach speed to account for a sudden drop-off in headwind component. The only time you would use less flap for landing is if your normal landing flap is a high drag setting, like 40 degrees. In that situation, you might want to land with 30 degrees because you don't want any more drag than necessary in a go-around, and you don't want to have to wait for your flaps to go from 40 to 30 degrees. If you need to go around in a gusty situation, a lot of drag is the last thing you need. You want lift.

So to summarize, unless you normally land with a very high drag flap setting, you don't need to change your landing flap setting. Just carry a little more airspeed on final in case of a sudden drop-off in headwind component.

I use full flap every time, no mater what the wind strength.
If its windy I come in with more power on.
Paul G