Paul_BB

Anyone else tried thisway oflanding:?

I have programed a switch so as to apply a constantoffset to the elevator. I have adjusted the offset value such that the plane flies level at a speedjust alittleover the stall speed.
Thus, when I am ready to land, Ipull the switch andadjust (lower) the throttle to a value A, such that the plane flies level downwind.Then Ireduce the throttle, turnand come in forthe landing. When the plane is aligned anda few feets overthe runway, I flare and I bring back the throttle tothe previous value A : the plane floats at its minimal speed and I can control very precisely the touchdown. Then I cut the throttle.

This way I am sure theplane flies atthe lowestpossible speed, even if the wind blows. Because when the wind blows it is difficult to estimate the airspeed. Ever since all my landings are successful.

bogbeagle

Let's put that into pilot' language.

You've trimmed for the correct approach speed.

You fly the approach with appropriate power.

You round out over the threshold and fly level with runway.

You reduce power and hold off until the aeroplane settles.



Yep, that, or a variant of that is pretty much what we all do when landing. Of course, I see the point you are trying to make ... that you can "set" the correct approach speed by clever use of the programming.

It sounds like a plan ... so long as you are prepared to adjust the approach speed, and trim for the new speed, when the wind is gusty.

Anyway, it seems to work for you and I guess that the "proof of the pudding is in the eating."

Oh, for a simple air-speed reference.

Paul_BB

Yes, I don't need to mess up the pitch trim anymore.

cfircav8r

My Feedback: (1)

Yes, regardless of what phase of flight, it should be trimmed for hands off. I agree that if you have gusty conditions you should increase the airspeed a little to prevent a stall. Also be aware that going to full throttle on some aircraft trimmed for landing can cause it to pitch into a stall. It might be a good idea to practice go around's at altitude with this setting, just to see how it reacts.

Paul_BB

Yes, when I tweaked the offset (trim deviation), I took into consideration possible gusty conditions: the reference airspeed is above the stall speed plus a little safety deviation.

Lnewqban

+1

Go-around's may become ugly with enough power.

Same for frontal gusts.

I would rather had the freedom of nose down at will.

AA5BY

Another concern is with the dreaded cross wind on the tail during base leg. That dreaded tail wind has gotten many of us who otherwise consider ourselves adequate pilots. Depending on the airframe, a number of designs will not be happy with the turn from base leg to final with a tail wind (cross wind in your face) and not putting extra speed on during such conditions can mean bad things in what some call coffin corner.

Part of the problem is that the downwind leg... isn't downwind and we don't feel the plane the same as typical and we may slow up to get it to drop altitude... then when turning base leg we don't add throttle and the airspeed gets precariously low... then that final turn bites.

BMatthews

Moved to Tips and Techniques since this isn't an aerodynamics issue.

Back in the day when we used to have trim levers that actually moved up and down and side to side instead of clicking I would drill and thread in a long 2-56 screw into the elevator trim lever so that I could find it easily with my thumb. The elevator trim became one of my primary flight controls since I tend to fly a lot of sailplanes and old timers. But even the high power sport models benifit from having the elevator trim readily accessable. The use of the screw to extend the trim lever both allowed me to find the trim easily and also to easily feel where it was postiioned. With today's click trims this option has been taken away from me/us.

We're now stuck with doing "tricks" such as yours to accomplish the same thing. What you did is a nice way of doing what used to be so simple. I just wish that more radio makers would include slider or slider like levers so that we could program them for this aspect. It's important for gliders/sailplanes in particular since the elevator trim is our throttle control for adjusting the flight speed.

Shoe

I use almost the exact same procedure when landing on an aircraft carrier... trim the aircraft for a specific AOA (8.1 degrees in my case) and then use the throttle to control altitude/glide path. Only difference is I don't flare. Oh, and I got full power at touch down rather than cut the throttle.

rmh

On the little 17 gram Vapor - we use exactly same technique
reduce power add AOA till the model is in very slow forward flight and very high AOA- I can land the model -in a room on a smooth 30" dia table

speedracerntrixie

My Feedback: (29)

The power required to maintain enough AIRSPEED to prevent a stall is the same regaurdless what the wind is doing. The airplane dosen't know nor care what the wind is doing.

Charlie P.

The only time I mix any elevator in for landing is with the flaps switch or slider just to prevent ballooning. Otherwise, I want to have the control of the model - not rely on the transmitter. Suppose someone barges towards you or you have to do a power on wave-off? I don't want to be futzing with switches in an emergency situation. Also, landing into calm vs. strong winds - doesn't that alter your elevator needs?

I do have a landing switch for the throttle that is the lowest setting. Off I can't accidently powder down so much it dies on me and it is a good taxi setting. On it is very low idle. Switch beside it is engine kill.

Lnewqban

Not completely accurate.
Gusts have a different effect on airplanes just because the inertia.

BMatthews

Yep, gusts can greatly alter the instantanious airspeed over the wings. The wind can change direction and velocity and the inertia of the model takes a while to catch up. But during that time the model ends up being affected quite a bit.

Charlie P, strong vs mild doesn't really alter the elevator needs other than if it's a variable gusty wind. If the wind is smooth it just means that you want to start the approach more overhead than way off downwind. Don't confuse airspeed with ground speed. Mind you if the model in the "approach mode" is flying so slowly that it's got a negative ground speed then it's time to alter the landing procedure and deal with the reality of having to actually make it back to the field. That's a situation where a single fixed landing mode elevator trim is just not going to work out.

cfircav8r

My Feedback: (1)

Airspeed is a function of AOA not power. If you set the trim and leave it the airspeed will stablize and remain constant. If you reduce power the airspeed will start to drop and this will make the elevator less effective, causing the nose to drop, this causes the airspeed to increase, causing the elevator to become more effective, until the airspeed is again stablized at near the same speed, but at a lower power setting. It may not be exactly the same speed as the prop wash across the elevator may be reduced causing a slightly higher airspeed, but that is dependant on the design of the A/C. When you have a wind gust the airspeed will suddenly increase causing the elevator to be more effective causing the nose to raise until the airspeed stablizes at the original speed. Then when the gust dissipates the airspeed suddenly drops, and if you were near stall speed to begin with you could stall before the plane can stablize. This is the reason to use a trim setting that maintains a higher speed during gusty conditions. Do we need to move this back to the aerodynamics section now?

speedracerntrixie

My Feedback: (29)

You guys are over thiking this. If the airplane were a fixed object you may be correct but it is not. The airplane has a set drag coeffecient that is pretty much the same unless a conrtrol input is introduced and even that has minimal effect. A gust will not significantly alter the airplanes AIRSPEED. It will however alter the GROUNDSPEED.



Lets see if I can explain this...............Lets say that to fly the airplane at 40 mph AIRSPEED, it takes 1/4 throttle to overcome the airplanes drag to do so. Now it gets hit with a 10mph headwind. The drag does not change so the airspeed remails the same, the groundspeed theoretically will drop by 10 mph. If you were to bump up your throttle to maintain the same groundspeed flying an approach tolanding with a 15 MPH headwind, you will be landing the airplane with too much airspeed making it difficult to keep on the ground and pitch sensitive at flare. How many of you guys have done that? I have, it's easy we think the airplane is flying too slow because it takes more time to get to the runway then we are accustomed to.

Shoe

You're missing the point about inertia. If a plane gets hit by a gust with a 10mph headwind component, it will take some time for the groundspeed to drop by 10 mph. During this time, the airspeed will not remain the same. This is one of the reasons why microbursts are dangerous to airliners.

pmerritt

My Feedback: (118)

He's from France. I bet he's sitting at a portable cafe table witha gorgeous French gal, sipping wine and eating cheese and crackers while he flies!

Ijust keep both hands on those two little knobs and fly them in according to wind, speed, and approach. I'd be in big time trouble if I took some aviation bible out and figured out how to dial in an auto-approach computerized function that some 737 should have.

Paul_BB

Ahem... This could have happen thirty years ago, but anyways it is forbidden to fly over French cafés.
But for pity's sake, don't think every Frenchman acts like Dominique Strauss Kahn.

bogbeagle

We Brits think you are all like Rene from 'Allo, 'Allo.

cloudancer03

My Feedback: (22)

with my electrics I do couple a couple of degrees of up for landing usally with my throttle.but only because its so darn light just a little bump on elevator sends it up.the added drag with my method makes a nice glide.but thats only on a real light electric .my gas planes like never.

MX240

My Feedback: (4)

Flying warbirds and IF the runway is long enough I plan the touchdown 50' past the end of the runway.

charlie111

I call it as most people do as flying it in.It also keeps the airflow more stable adding power when landing.Remember to lower the wing on side that crosswind is comming from!Or it will flip your plane opposite rudder will have to be used to keep you straight.But with a little extra power the drag is minimal..If pushed to the extremes they call it crabbing and it helps if you come in high you can lower the nose and with airleron and rudder are opposite to the max it works like an airbrake helping you loose that extra altitude.

Bozarth

My Feedback: (15)

Please - using a switch to trim for landing does not prevent you from having "control of the model - not relying on the transmitter." It simply moves the elevator to a different position - YOU STILL CAN MOVE THE ELEVATOR! Holy cow!

Kurt

Bozarth

My Feedback: (15)

You are blending three concepts into one. Lowering the upwind wing is not crabbing. Most call this the "wing low" or "wing down" technique. Crabbing normally refers to letting the nose weather vane into the wind regardless of the ground trajectory of the plane. Lastly, "slipping" is what you addressed in your last sentence.

Kurt