Quick question on landing speed

[Wolf Rider]

The AoA indicator, (just below and left of the Compass - item 6 on the first image) is a very useful indicator... use trim the set the pitch so the needle sits between 19 ~ 21 on final, for the recommended approach speed.

Once you get your basic pitch right, the (reverse of the normal situation) nose up/ down for speed and throttle up/ down for altitude (in reference to the glideslope) when flaps are deployed will start to make sense.

 

If your plane is pitched correctly and you find yourself below the glideslope, pushing the throttle up a bit, causes the plane to move along a more horizontal line (remembering here that you are on a controlled sloping descent) and move forward to the glidescope. Keep in mind that deploying flaps, alters trimmed pitch

 

With speed... well, we can't use the throttle anymore for that, and seeing as were are already on a sloping path (not flying horizontally) to the airstrip, so the underplane is acting as a brake anyway - we might as well continue to use this for speed control. We nose up a bit, so to present a bit more underplane surface area to the airflow, and similarly to speed up a touch - lower the nose to reduce the amount of underplane surface area is exposed. (second image gives an idea of what happens)

 

Deploying landing gear, slows you down a bit

 

 

With all that, its now relatively easy to keep your eye on the donut, crosshairs in the centre and the pipper on the end of the runway... look for the pipper "sliding" up or down the runway, (sliding up the runway - throttle down) which you need to do for the last couple of hundred metres.

Edited January 17, 2014 by Wolf Rider

[BitMaster]

...

 

With speed... well, we can't use the throttle anymore for that, and seeing as were are already on a sloping path (not flying horizontally) to the airstrip, so the underplane is acting as a brake anyway - we might as well continue to use this for speed control. We nose up a bit, so to present a bit more underplane surface area to the airflow, and similarly to speed up a touch - lower the nose to reduce the amount of underplane surface area is exposed. (second image gives an idea of what happens)

 

 

Hey Wolf Rider,

 

I think you reversed the RL attitude that happens on approach. You are right with that you DO NOT control air speed in its limits for landing approach with the throttle, you far better do this with lowering or lifting the nose BUT the effect is completely opposite from what you described. It is not only in this sim like this but also in RL flying. With a higher AOA you ALWAYS bleed of airspeed. Considering the fuselage as a plane too makes this even more dramatic

..and with lowering those nose you ALWYAYS gain airspeed. By applying throttle you move your spot of actual touchdown further down the runway and by reducing throttle you touchdown a bit closer to where you started from. It MAY be, in limits of 1-2° of AOA and heavily depending on the airfoils used on the inner wing if you could possibly be right in special cases and rare aircraft tho I do really think this is not how it could possibly be in any aircraft at any given AOA or airspeed. Usually the outer wing is tilted 1-2° down to avoid tip stalling when approaching high AOA, thus causing the inner wing to stall first and have a stable stall straight down instead of a wing tip stall which is a lot harder to recover from in time. I don't see why a stalling wing should cause less drag with all the turbulences it creates when being near stall or already in stalling-limits ( the outer wings keep you straight, tilted 1-2°, and you most likely won't even feel that your inner wing already stalled on you, there only thing you will notice is a greater speed directed DOWNWARD but NOT in your direction of forward movement.

 

This only applies in SMALL quantum, as soon as you overdo either maneuver, nose up/down or throttle +/- you loose your general attitude and you better come around for a 2nd approach. Giving full throttle will not only put your touchdown further down the runway but also accelerate you a lot

and when pulling too hard back you will stall since you were just THAT far from stall speed anyway

and pushing too far forward will not give you enough space to maneuver to catch the plane before it hardly sits down on its gears, usually causing bad RL damage.

 

What I do when I get a new Plane in DCS or as a new R/C plane is...fly it SLOW, try to fly "3 errors high" so you got time to recover when u overdo it..and you MUST overdo it to find its limits and find the way the plane wants to get out of it. Fly a few fuel tanks in real LOW SPEED high AOA to get the feeling for your plane. Circle around at high AOA, forced to slam aileron left to right to keep it from stalling and get to know your tool of joy. When close to stall speed, most control surfaces on most planes tend to become very ineffective and need a lot more travel to have the effect you hoped for, thats why I said before, slam aileron fast between max left and right. Also elevator usually only needs full throw when in slow landing approach, in normal flight SLIGHT movements can present you with a 3G turn while the same throw at low speeds just cause next to nothing with the plane. This is heavily effected by CG ( centre of gravity ) and it does matter how much fuel is stored in front of CG and how heavy your wings are loaded with fuel/weapons since a heavier mass it a lot harder to get moving than a lighter mass, considering putting in only little force through reduced efficiency.

 

Each planes handles a bit different on this, but they all go the same way. like cars generally don't drive good on ice, you always have to think far more ahead and apply little force in most cases and some brutal force in others to get the same response when compared to race track tar and racing rubber on your wheels.

 

Other things may happen or may not happen too, like effect inversion.

 

You roll left but your plane rolls right, you pull up but you go straight down... this is BAD !

 

I only know the german name for it, "Ruderverklehrung" but it is present at not only too high airspeed, it can happen on too little IAS as well on some airplanes or airfoils. It really depends on the airfoil(s) being used on the wing what the actuators actually do at what speed, how much force/throw is needed to achieve a desired change of attitude of your aircraft.

 

We would actually have to study aerodynamics and airfoils to get all this covered but this is far too complex to describe in even 10 pages. I have read several books about that, used to design my own wings with CAD and had to read a lot and fly a lot to understand and finally get the feeling for it, described I don't sit in those cockpits, the only thing I have to "feel" what the plane does is pure eyesight from my stationary POV from where I radio control my aircraft.

 

There are many habits a plane can have and you should know them all before the plane teaches you about its character but at some point you gotta bite the apple and give it a shot. In a sim you can respawn, as a R/C pilot you crash 4k€ in the ground and spend many many hours repairing, in RL you might die.

 

Know your aircraft, read about its attitudes to avoid errors others have found out and fly fly fly to get the hang on it.

 

 

Bit

Edited January 18, 2014 by BitMaster

[Nealius]

The whole "use pitch to control speed and throttle to control descent" on landing has led me to nothing but confusion. One cannot be adjusted without adjusting the other to compensate, so you are never just going to reduce throttle and not do anything with the stick, or move the stick and not do anything with the throttle.

[BitMaster]

The whole "use pitch to control speed and throttle to control descent" on landing has led me to nothing but confusion. One cannot be adjusted without adjusting the other to compensate, so you are never just going to reduce throttle and not do anything with the stick, or move the stick and not do anything with the throttle.

 

No, you are wrong here, I only adjust one or the other unless I need both adjusted.

 

If I need both adjusted I make a VERY QUICK decision if it better come around a 2nd time if I can. ( for my actual RL R/C planes without a respawn button )

 

In a SIM you can try all you want and thus SPOIL your piloting skills a lot. Nothing spoils my R/C skills more than flying stupid in Sims and then using this trained behavior on the strip. I learned that the hard way !

 

When dead stick ( still standing prop or flamed out turbine ) I have no other choice but only nose up/down and banking the plane to slow down if I am FAR too fast FAR out.

 

When you are close and too fast and no engines there is NO GOLDEN MOVE to get you slowed down, you made your mistake further out in your approach and can't be fixed anymore, neither in a SIM or RL, you are gonna shoot over the runway, usually ripping one or more legs off, ruin the fuselage and end up being stopped by hedges or trees.

 

 

GUYS, learn landings: This is THE most thrilling maneuver of all there are.

 

You ask WHY ?

 

Well, easy, LOOK BELOW, how much air have you got left to maneuver out, how much extra airspeed to you have to pull out. Both values are next to zero, meaning NO 2ND CHANCE.

 

Thats why I wrote above, get yourself "3 errors high" and up there, do some HIGH AOA LOW SPEED rounds to get the feeling. Nothing else will teach you that quick the feeling for your aircraft close to stall speeds.

 

applies to SIM and RL / R/C

 

Bit

Edited January 18, 2014 by BitMaster

[BitMaster]

This is what I do to land my balsa built Top Flite 1.6m wingspan P-47 Thunderbolt in R/C. I don't bank or overhead this plane unless dead stick and no other chance: ( this pane has a VERY HIGH wing load, 7.75kg fueled and armed ( 3 working drop tanks or bombs )

 

Fly a pattern you have thought out before, don't just head to the runway without a plan in your head what to do when !!

 

On base leg I drop gears down and check them visually

On turning in and fairly high I lower flaps 60°

Steep approaches are my favorite and are easier to control for my liking

Check if your GENERAL speed is ok by eyesight ( needs experience )..adjust this by throttle a last time

Check if you would hit the threshold by eyesight ( also needs some experience )

get the right AOA and don't change it unless forced, usually my touch down spot is OK.

Depending on cross wind/head wind you HAVE to work with the throttle GENTLY*.

*Too fast throttle movements turn my plane around the prop and a crash is imminent.

Apply rudder to compensate any drift due to crosswinds ( hard in RL )

Apply aileron and HANG your wing into the wind, this prevents your plane from being tossed over by gusts ( wing a BIT down where the wind comes from ).

Adjust AOA just before touchdown to flare in for a nice three point touchdown.

During the LAST ⅓ of the approach, the above mentioned throttle/elevator technique is used to control touch down point and speed, not before !

As said in this thread, the GENERAL speed is adjusted by the throttle, only on the last ⅓ you control speed speed by nose up/down and touchdown spot by throttle.

 

At that last point, my elevator is almost at FULL BACK before actual touchdown.

 

KEEP THE ELEVATOR FULL BACK for slow down, this prevents the AC from lifting again by forcing a stall on the tail wing, keeping you safely pressed down on the ground and avoiding a prop from being replaced and/or bend drive shaft.

 

Taxi back with caution, full up elevator applied throughout taxiing on rough grass/terrain, again to avoid tipping over.

 

Park, grab a beer and chat to pals :)

 

Most other planes, like gliders, Hotliners, Jets are A LOT easier to land, especially Jets with delta wings as they won't stall that easy at high AOA and giving you greater freedom in your attitude.

 

Low wing planes, like the P-51, are the hardest to land. If you can land a P-51 in DCS you know how it works. Any Su will be easy compared to the low-wing Mustang and heavy torque Merlin up front with a Prop that can easily swing the whole AC around itself if you don't move the throttle with brains.

 

Bit

Edited January 18, 2014 by BitMaster

[BitMaster]

Other ways to land:

 

I have another low wing scratch build balsa dogfighter that only has 88cm wingspans and no gears. That thing is a lot lighter and has a lot less drag, so it comes in rather fast for a belly landing.

 

Come in shallow, steep will make you overshoot.

Reduce power to idle

flare along the strip with a modest AOA until she sits herself on the ground

 

By far this doesn't look as nice as her big sister, but the small one aint got flaps, low wing loading and a fast airfoil. They look alike but fly totally different just by changing the airfoil and weight.

 

My Jets are a lot easier to land since you can flare off any extra airspeed by just giving some more AOA ( you still need to know where max AOA is to not overdo it )

 

Gliders are the easiest, the have multiple flaps allowing Butterfly config, allowing you to land in a almost vertical spiral until they just sit down or have very very effective air brakes, allowing you to throw the Air-Anchor...

 

Many ways to land, the one we tried to explain to you just applies to some wing/load/drag configs Aircraft can have. It is actually the hardest one and needs the most skills and gentle fingers.

 

Delta Wings are novice proof. You might wanna give the Su's a shot to get the feeling for FLARING HIGH AOA approaches. You almost can't over pull them when slow, the won't raise their nose higher due to lack of lift/efficiency. Good to get used to high AOA !

 

Bit

[Nealius]

No, you are wrong here, I only adjust one or the other unless I need both adjusted.

 

It's impossible to maintain approach AoA without adjusting both stick and throttle. Adding/reducing power without compensating with the stick will result in a decrease/increase in AoA. Forward/Aft stick movement without compensating with the throttle will also result in a decrease/increase in AoA.

[Wolf Rider]

Hey Wolf Rider,

 

I think you reversed the RL attitude that happens on approach. You are right with that you DO NOT control air speed in its limits for landing approach with the throttle, you far better do this with lowering or lifting the nose BUT the effect is completely opposite from what you described. It is not only in this sim like this but also in RL flying. With a higher AOA you ALWAYS bleed of airspeed. Considering the fuselage as a plane too makes this even more dramatic

..and with lowering those nose you ALWYAYS gain airspeed. By applying throttle you move your spot of actual touchdown further down the runway and by reducing throttle you touchdown a bit closer to where you started from.

 

 

well... you've said exactly the same thing I did but in a different way, but digress slightly off "landing". lets just keep it to "Landing"/ "Landing Configuration"/ "Maintaining Slope and Speed", and not confuse things

 

 

the thing with RC planes is the lack of weight, compared to the real thing... you may have an accurate scale model, but you don't have accurate scaled weight and accurate scaled atmospherics

 

 

It's impossible to maintain approach AoA without adjusting both stick and throttle.

 

which is why you get into the correct configuration first.. from there it is just simple adjustments as required (in good flying conditions)

 

Adding/reducing power without compensating with the stick will result in a decrease/increase in AoA. Forward/Aft stick movement without compensating with the throttle will also result in a decrease/increase in AoA.

 

when flying along normally... gotta keep in mind though, when landing (on Final) you are basically on a glide

Edited January 18, 2014 by Wolf Rider

[PFunk1606688187]

It's impossible to maintain approach AoA without adjusting both stick and throttle. Adding/reducing power without compensating with the stick will result in a decrease/increase in AoA. Forward/Aft stick movement without compensating with the throttle will also result in a decrease/increase in AoA.

 

Its a mistake to think that you won't need to alter one or the other on a landing. What you should be thinking is now that one doesn't affect the other, but that when sink rate is off you alter power and when speed is off you alter pitch.

 

Also, aircraft are designed to want to return to the AOA they were trimmed for so when getting into a landing configuration you want to realize that speed will be more stable than sink rate during instantaneous changes. Trim for a speed and then make gentle adjustments to power and you will see the TVV move up and down while your speed will remain steady. Changes to pitch will tend to have more instantaneous effect on sink rate in my experience.

 

The phrase of "Pitch for speed, power for sink rate" is overly simplistic, but its at the core of how you manage a stable landing approach.

 

Consider this. Trimming nose us leads to a speed reduction but it also leads to an immediate reduction in sink rate. To stay on your 3 degree glide slope you want to reduce power. As the aircraft settles into its new AOA the speed reduces and your sink rate does as well so now you add power to keep from dipping below the glideslope.

 

In the above you made changes to the aircraft's configuration and had to compensate as a result. Thats inevitable, but in the end you're still changing pitch(trim) to control speed and power to control sink rate. That changing one forces you to change another doesn't in any way invalidate the concept behind the phrase. Its just not as simple as the phrase sounds.

 

That said, once you are fully configured, with flaps and gear down, speed brakes out, trimmed on speed for landing, changing your power gently will have no meaningful effect on your speed. At this point you really can alter one without altering the other. This is because the trim keeps your plane at the right AOA and by not slamming the power around you will not generate an oscillating pitch that would push you off the glide slope.

 

The most important part of landing is being stable in your approach. Its a lot harder to corral the plane when making rapid configuration changes, ala the overhead break. Even so the same wisdom applies and when on the perch you'll be in final configuration anyway, so then it just means that your final approach is shorter but in the end follows the same rules.

 

Its mostly about anticipating those changes and knowing whats coming rather than reacting to them after they throw you off glideslope. Also, its worth noting that landing involves various stages that involve different levels of required pilot input to remain on the glidepath.

Edited January 18, 2014 by P*Funk

[Nealius]

Trim for a speed and then make gentle adjustments to power and you will see the TVV move up and down while your speed will remain steady. Changes to pitch will tend to have more instantaneous effect on sink rate in my experience.

 

Yes, but when the TVV moves from that power adjustment your AoA and speed will change as well. I can see it clearly in the F-16's AoA bracket in the HUD when flying BMS, and I can see it on the AoA indexer in the A-10 in DCS. When landing your airspeed and AoA are linked.

[Headspace]

The problem is that with a jet, it takes time for the engines to spool. This is especially true on older generation jets. You don't want to be a throttle jockey on landing. Get a good approach speed going (relative to how heavy the plane is, what the wind is doing, and so on) and landing will get much easier.

 

DCS tends to model all of this fairly well in the game. You don't want to get into the habit of making huge power changes right before landing. Take the throttle out only after you know you're committed.

[Wolf Rider]

Yes, but when the TVV moves from that power adjustment your AoA and speed will change as well. I can see it clearly in the F-16's AoA bracket in the HUD when flying BMS, and I can see it on the AoA indexer in the A-10 in DCS. When landing your airspeed and AoA are linked.

 

if your ILS tells you, you are below the ILS glidepath, throttle up slightly(which nudges the plane forward a bit) to ascend to the ILS "beam" (which is what you want to ride down - glideslope) and then pulling back the throttle a tad to "capture" the glideslope. What has happened is, you have slightly increased your angle of descent, which does increase the AoA even though your plane's inclination may not actually have changed at all (AoA is the angle of the wings in relation to the direction of travel), in the process slowing down a bit.. thereby requiring a slight pitch down to pick up some speed if required.

Edited January 18, 2014 by Wolf Rider

[Nealius]

I'm not the OP of the thread, and I'm proficient at landing ;) AoA and speed are intrinsically linked on approach. Period.

[Wolf Rider]

I'm not the OP of the thread, and I'm proficient at landing ;) AoA and speed are intrinsically linked on approach. Period.

 

 

Pitch angle and speed are linked in landing... Angle of Attack is the angle of the wing chord in relation to the plane's direction of travel.

[Hamblue]

Besides those just arriving, is there anyone here who can't land? :music_whistling::music_whistling:

Unless you are going for your pilots license do what works for you.:thumbup:

[BitMaster]

well... you've said exactly the same thing I did but in a different way, but digress slightly off "landing". lets just keep it to "Landing"/ "Landing Configuration"/ "Maintaining Slope and Speed", and not confuse things

 

 

the thing with RC planes is the lack of weight, compared to the real thing... you may have an accurate scale model, but you don't have accurate scaled weight and accurate scaled atmospherics

 

 

 

Well, I agree to some extend with weight, that is why I used my heaviest plane for this.

 

The aerodynamics are exactly the same up to about 0.7 Mach, beyond models also have the some commons symptoms bigger AC encounter, like static charge/discharge on protruding edges etc... which are very hard to eliminate with given resources and space insite the wings/fuselage. One Me-262 I know that goes well beyond 550 km/h had severe problems with static charge and usually all turbine models have a speed limiter by pitot that stops acceleration at about 450 km/h max IAS. It also gets very hard to control them from a fixed POV, you basically end up in a constant circle around yourself with about 1km diameter

 

Airfoils behave the same in all scales, air molecules are very tiny and don't distinguish if the chord is only 15 inches or 150 inches. That is the reason why all new AC are modeled as "model" with exact same airfoil and shape to study aerodynamics. You just should not change to another airfoil.

 

Given the size of the USAF Mach 8 HyperSonic jet.... well, I know many R/C of twice the size and weight. Also many drones are of the size of turbine powered jets or gliders. Many gliders are bigger than most biplanes... funny but true. The AN-2 is maybe the only Biplane that is bigger than most large scale gliders. A don't consider 7m wingspan a small model.

 

What really matters is the wing load but you can accurately calculate the same wing load relationship with any given scale ratio. Believe me, I did it on my P-47 D23 with 7.75 kg.

My P-47 has a higher wing loading ratio than the original, the only thing that gets her up is a different Selig Airfoil ( actually 2 of them, inner & outer wing ) compared to the S-3 original airfoil

that was developed for high altitude ( thin air ).

 

They do differ in some respect, but just like with cars and R/C cars, you can't cheat physics and those laws apply to any size, from molecules up to an A380.

 

Also, some of my R/C friends are real world hobby pilots ( IFR, single and double engine), Airbus drivers and 1 is even an A10 warthog driver in Spangdahlem around my corner and one of my customers is a former F-15 driver and former F-15 flight teacher. All but the F-15 driver also fly models.... they think they all behave the same or so close to it that it doesn't matter much when going 0.1-0.5 Mach which is our speed envelope with models. We just don't have our butt in the cockpit and thus lack the butt-o-meter to actually feel G-forces to counter-react with control input.

You have to have a trained eye and experience to compensate this disadvantage.

 

Supersonic or very high altitude does change things seriously and other factors come into play, that is why most supersonic AC being modeled do get a different airfoil to adjust their behavior for subsonic flight and dense air. the rest is just the same...if you mess it up you basically crash.

 

I also do remember one R2-GeeBee...the only way that company, a world known FiberGlass company with WC winners as pilots and models, got that thing to basically fly in some sort of controllable manner while landing was to stick to the original airfoil and not try to tame it with modern NACA, Selig or RG airfoils. The GeeBee is known as one of the hardest planes to land in RL and R/C, the sentence "any landing you can walk away from is a good landing" could possibly bee from a GeeBee driver. They are lucky if they got it down in 1 piece without nose stands, torn wingtips etc... Its an insane plane to race but a beast to land. Thats why many pilots don't dare to climb into one.

 

 

Bit

[Nealius]

Pitch angle and speed are linked in landing... Angle of Attack is the angle of the wing chord in relation to the plane's direction of travel.

 

That's not correct. Pitch angle is is the angle between the plane's longitudinal axis and the horizon--where the aircraft's nose is pointed. Angle of attack is the angle between the wing chord and the airflow/velocity vector. The airflow relative to the wing chord is more important than pitch angle because as speed decreases AoA must increase to maintain the same lift, and as speed increases AoA must decrease to maintain the same lift. It works the other way around too. As AoA increases speed must decrease to maintain the same lift, and as AoA decreases speed must increase to maintain the same lift. They are linked by the physics of flight, and not just in landing.

[Wolf Rider]

"Relative wind" (Airflow) generally, is the same as "direction of travel".. you can achieve the same AoA at different pitch angles, in a climb or in a dive or in level flight (note: these are directions of travel). Similarly, you can arrive at a high or a low AoA in level flight (travelling forward)... again, this depends on the pitch angle of the aircraft if throttle setting isn't altered to suit.

 

generally, when landing in landing configuration and you need to slow down a bit, you pitch up

Edited January 19, 2014 by Wolf Rider

[Wolf Rider]

You can also just kick one of the pedals and apply opposite roll, that'll really slow you down :)

 

lol, and get near the ground a bit quicker :)

 

 

 

@Bitmaster...

 

I mentioned "Atmospherics" not "Aerodynamics". Some things are achievable with an RC plane which can't be with a real world plane without it ripping its wings off.

Edited January 19, 2014 by Wolf Rider