HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Aug 12, 2011, 12:47 PM
Registered User
jeb6684's Avatar
United States, PA, Gettysburg
Joined Mar 2011
346 Posts
Discussion
Landing Tips/Tricks

Anyone got any good tips for performing clean landings. I have a super cub and parkzone corsair. I can land the cub alright but I still have problems with the corsair.
jeb6684 is offline Find More Posts by jeb6684
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 12, 2011, 01:09 PM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
4,611 Posts
Conceptual problem maybe? Okay let's look at it like full scale pilots are trained.

You control altitude with your throttle. You control airspeed with your elevator. Kapeesh? Yeah, I know there's crossover, but lets go with the idea.

The more nose high you fly, the slower your airspeed is going to be. Let's say you're trimmed out for level flight and cut the throttle. Sure, your airspeed will momentarily drop off, but the nose will drop automatically regaining your airspeed and you will begin to lose altitude. We're going to use that idea to land.

Practice coming down the runway straight and level 4' altitude. Get the feel of where the throttle has to be for a nice slow but very controlled level pass.

Then on another pass, when you are not yet to the runway, just cut the throttle back gently. You'll see the plane just establish a sink rate that will end in a landing. You can change the rate of sink by dialing in more or less throttle as you need. You might be surprised on your Corsair how much throttle you'll use on landing and how fast the plane will be moving.

Really you're letting the plane land itself. Just keep the elevator where it is. You might pull the nose up just slightly at touchdown.
Rockin Robbins is offline Find More Posts by Rockin Robbins
Reply With Quote
Old Aug 12, 2011, 02:12 PM
Registered User
Wasaga Beach, Ontario
Joined Aug 2007
1,198 Posts
The corsair is a little tricky to land because it has a tendency to float, and it's landing gear is VERY springy. I actually programmed in spoilerons to mine to make landing easier.

The corsair I do a long approach, sometimes twice as far as the Supercub. This gives me a lot of time to bleed off altitude and set up for landing. I also flare the corsair and hold it off about 1-2' off the ground as I bleed speed. The less speed the better when touching down with that bird.
kalnaren is offline Find More Posts by kalnaren
Reply With Quote
Old Aug 12, 2011, 02:51 PM
Citizen #96
Steve Graham's Avatar
NE Denver, CO
Joined Sep 2007
731 Posts
At the end of the day realize that controlling the dynamic forces acting on an airplane to create the perfect satin smooth finish to a flight is a challenge that will humble you for as long as you fly and some days will just be better than others. This takes practice and at a recent IMAC contest I observed some very highly skilled pilots who clearly never gave much time or consideration to this challenge. Also be aware that if you master the fundamentals you should expect that while all your landings may not be greasers they will be safe and un-damaging to the model because you touch down on in the first portion of the runway, on centerline and at a proper speed. Here is a start.

Read as much as you can about how a wing creates lift and what happens at various angles of attack. Most important in the landing phase is how the lift and drag curves interact. A wing creates more lift at higher angles of attack. This is true until somewhere around the critical angle of attack. This is defined as the point beyond which lift decreases dramatically and drag increases dramatically. A wing also creates more induced drag (the portion of total drag generated through the act of producing lift) such that below a certain angle of attack you will also need to increase power to maintain vertical performance.

This brings us to the idea you hear so many people talk about that power controls altitude and pitch controls speed. Instead of altitude I prefer the term "Vertical Performance" because it more accurately describes what we are trying to achieve. Saying altitude sort of leads the reader to the idea that we are trying to maintain level flight. Vertical performance can mean 1. Staying level or 2. Climbing or descending and the rate of ascent/descent. In the case of the approach to landing we are talking about a fixed Glide Path Angle, GPA, with reference to the horizon. We control this GPA with power and to some extent AOA.

Try this experiment. It will enhance your awareness of these forces. Take the plane up to altitude so that if you inadvertently get too slow and stall you have room to recover. From straight and level flight reduce the power to idle and use the elevator to slow slightly below cruising speed and allow a descent to begin. Note a couple things here. The stick position you are holding which determines the AOA, airspeed in other words for unaccelerated 1 G flight, and the GPA. Try also to the best of your ability to "see" the AOA. This will be the pitch attitude of the plane with reference to the GPA. In level flight the AOA and the pitch attitude relative to the horizon are one and the same but any time the aircraft is climbing or descending the GPA has to be added or subtracted from the aircrafts pitch attitude to evaluate AOA. If you can develop your ability to "see" or evaluate your AOA based upon stick position and pitch attitude vs GPA you will be head and shoulders above most who fly RC.

Now begin increasing the up elevator deflection in very small increments and allowing the aircraft to stabilize each time. This will take a number of climbs back to altitude each time you get too low. What I want you to see is that initially as you increase the elevators angle that the aircraft both slows down and begins to flatten it's GPA. In other words you stretch the glide. This is because the new elevator position has increased the AOA which increases the lift of the wing and the slightly lower speed which reduces the parasitic drag. Parasitic drag decreases with reduced airspeed. As you continue to experiment with increased elevator angles and their effects on the glide path watch carefully for a point where the model will actually begin descending at a steeper GPA. This is the point in the drag curve where because of the high angle of attack induced drag has begun increasing dramatically and therefore the total drag curve, induced plus parasitic begins rising. In a small lightly wing loaded aircraft ie. our smaller models especially this zone is small, subtle and a short distance from the actual stall but it can be manipulated allowing you to add drag and control the descent with another tool besides just power.

Be aware that when you are operating in this area, sometimes, called behind the power required curve that the wing will have very little energy left to flare and may actually require a very small amount of power to cushion the flare.

Most approach and landing issues I have seen relate to a fundamental failure of the pilot to understand or control the forces acting on the model in slow flight. The pilot may get too slow and when the model begins to sink he tries to stretch the glide by increasing back pressure causing either an even higher sink rate or a stall. Far more often the pilot is so unaware or afraid of his ability to recognize proper AOA for approach without stalling that he comes zooming in at over 2 times stall speed and flies off the far end of the runway while waiting for the airspeed to decay in the flare or forces the model on the ground too fast resulting in bounces, pilot induced oscillations and loss of control situations leading to bent parts.

For further reading I suggest for the umpteenth time "Stick and Rudder"

Steve
Steve Graham is offline Find More Posts by Steve Graham
Reply With Quote
Old Aug 12, 2011, 06:28 PM
Registered User
jeb6684's Avatar
United States, PA, Gettysburg
Joined Mar 2011
346 Posts
Hey Steve, thanks for the detailed explanation. Now if my thumbs would only do what my mind tells them to do.
jeb6684 is offline Find More Posts by jeb6684
Reply With Quote
Old Aug 12, 2011, 06:51 PM
Registered User
Fla.
Joined Apr 2005
986 Posts
A GOOD landing will result from a GOOD approach !!!!! Enjoy !!! Red
redh is offline Find More Posts by redh
Reply With Quote
Old Aug 12, 2011, 09:19 PM
Just "hanging" Around
3D-Dabbler's Avatar
Richmond, VA
Joined Oct 2009
1,589 Posts
Here is the best write up that I have seen that really helped me "put landings to bed" as something that I even think about. Now it is just like a machine.




Quote:
Originally Posted by blucor basher View Post
I posted this in the 47" SHP thread, equally applicable here:


1.Landing is a maneuver, like any other. You are the pilot, not the passenger. The very first step to making good landings is to take responsibility for them. If you are at the field, and you see a pilot make a bad landing, and he turns around and says "the plane did..." then you can be pretty sure he's never going to be a landing expert. Once a pilot can say "I screwed that up, I need more practice" (about any maneuver) he is on his way ot being an expert.

2. CG

CG (Center of gravity) is important for landing. When you are landing, you should (if you are doing it right) be flying slowly on final approach. We are all aware that if we go too slow, our wing will reach a speed at which it no longer works and will stop flying. We call this a stall. When we stall, we lose lift, and the plane will fall out of the air.

However, our aircraft has two wings (if it's a monoplane)...one in front, and one in the back (the horizontal stabilizer with elevators). In flight, the main wing holds the plane up, and the tail wing provide up or down lift to hold the plane stable. This is why a nose-heavy plane requires some "up" trim and why a tail-heavy plane requires some "down" trim (and why expecting your elevator to always end up perfectly in line with your stabilizer is not correct).

When you slow way down for final approach, the smaller tail wing stops flying first. As the tail wing loses efficiency, the balance of the plane takes over. A nose-heavy plane will drop its nose (the heavy end) and a tail-heavy plane will drop its tail (the heavy end). Dropping the nose is not a problem...dropping the tail causes the plane to slow down more and we may stall. This is why a tail-heavy plane is more difficult to land, because the pilot has to use elevator to push the nose down to maintain flight speed.

You might want a tail-heavy airplane for 3d tricks, but first be sure you can land it. To help:

3.Throttle

Do not glide down to landing. Your throttle is a speed *control* and if you set it correctly (about 1/8 on the SHP) it will help to keep your plane at the proper speed on landing, not too fast and not too slow.

If you learn to fly a full-size plane (or learn to fly an RC plane correctly) you will be taught at some point to fly a "stabilized approach". This means that your landing approach is stable, in that it has no time limit. You could start your approach at 20 feet high or 2,000 ft high, and you can fly in this mode as long as you want.

The opposite of a "stable approach" is a "decaying approach"...this is an approach flown without enough throttle or too slowly which has a time limit. The plane is slowing down (because there is no throttle) and the pilot is trying to get it on the runway before something bad happens.

To fly a stabilized approach, put the nose down about 10-15 degrees, use 1/8 throttle or so, and point the airplane at the spot you want to land. Start high enough and far enough away that you get a chance to fly a stabilized approach down to the runway. Don't "flare" or do anything else until you are very low. If you cut the throttle and pull back on the stick, make sure you're only ankle-high. Too many pilots want to have a dramatic flare at the end of their approach...leave that to the experts. Just fly down to the ground and close the throttle for the last foot or so. Done.

4.Elevator

The elevator is the important control for landing. DO NOT land on 3D rates. Use your low rates. First, fly a pass down the runway about 2 feet high on low rates at about half throttle. Can you do it? For most of us, probably not. Lower your low rates and increase your low rate exponential until you can smoothly fly just above the runway consistently and smoothly. When you are flying a stabilized approach, having the correct elevator repsonse will allow you to actually pilot the aircraft in a straight line, rather than fighting a bucking bronco. Get your elevator repsonse right!

5.Observe

Watch people who can land. Watch people who cannot. See their habits.

What we do not want to do is to go up really high, cut off our motor, and dive at the runway, then pull up and glide along the runway, bouncing up and down, hoping to be able to smack the runway on a lucky bounce.

Instead, we select low rates, select low throttle, point the nose 10-15 degrees down toward the end of the runway and fly a smooth straight line. When we are very low we cut our throttle and bring the aircraft to level and let it touch down.

If we mess it up, we make any necessary repairs, change our CG or transmitter as needed, and try again. Once you know how to land, your repair bills go way down.
Remember that the 10-15 degrees nose down is for your approach. You don't impact the runway at that angle. With a shallow nose down condition you should not be picking up a ton of speed. This isn't a dive at the runway from 400 feet up. You should have already scrubbed off a lot of speed and altitude before you start the descent to the runway.

Make sure to level out above the runway (ankle high). Leveling out too early is better than leveling out too late. Get some practice, progressively leveling out lower and lower with less speed each time but still above stall speed.

Something that helped me a lot was flying "ankle high" up and down the the entire length of the runway at various speeds trying to get it slower and slower but still stable. Then you can get a feel of at what speed the plane will stall out. When you stall out at ankle height then there isn't going to be any damage to the airframe. You will go "WOW, I landed unintentionally and it was a beautiful landing ".

So there is nothing to worry about. Once you get enough practice at that the next thing you discover is that you can cut the throttle at any time you want at that height and pick where you land.

The key is getting low enough, far enough out prior to reaching the threshold of the runway. That gives you enough time to lose any excess speed and touch down.

Keeping the plane nose down and then level once you are just above the runway keeps me from having my throttle set too high.

I used to have a lot of problems with coming in nose up. The throttle setting is much higher. When I get too slow and start to stall, the instinct is to apply more throttle and it is easy to overshoot and pop back into the air (especially when you are releasing elevator at the same time). The right thing to do at that time is go around. Correcting a pop up usually results in porpoising from over controlling and a hard or crash landing.
3D-Dabbler is offline Find More Posts by 3D-Dabbler
Reply With Quote
Old Aug 12, 2011, 10:58 PM
Registered User
United States, TN, Franklin
Joined Jul 2011
35 Posts
Quote:
Originally Posted by 3D-Dabbler View Post
Here is the best write up that I have seen that really helped me "put landings to bed" as something that I even think about. Now it is just like a machine.

Quote:
Originally Posted by blucor basher
Originally Posted by blucor basher
I posted this in the 47" SHP thread, equally applicable here:


1.Landing is a maneuver, like any other. You are the pilot, not the passenger. The very first step to making good landings is to take responsibility for them. If you are at the field, and you see a pilot make a bad landing, and he turns around and says "the plane did..." then you can be pretty sure he's never going to be a landing expert. Once a pilot can say "I screwed that up, I need more practice" (about any maneuver) he is on his way ot being an expert.

2. CG

CG (Center of gravity) is important for landing. When you are landing, you should (if you are doing it right) be flying slowly on final approach. We are all aware that if we go too slow, our wing will reach a speed at which it no longer works and will stop flying. We call this a stall. When we stall, we lose lift, and the plane will fall out of the air.

However, our aircraft has two wings (if it's a monoplane)...one in front, and one in the back (the horizontal stabilizer with elevators). In flight, the main wing holds the plane up, and the tail wing provide up or down lift to hold the plane stable. This is why a nose-heavy plane requires some "up" trim and why a tail-heavy plane requires some "down" trim (and why expecting your elevator to always end up perfectly in line with your stabilizer is not correct).

When you slow way down for final approach, the smaller tail wing stops flying first. As the tail wing loses efficiency, the balance of the plane takes over. A nose-heavy plane will drop its nose (the heavy end) and a tail-heavy plane will drop its tail (the heavy end). Dropping the nose is not a problem...dropping the tail causes the plane to slow down more and we may stall. This is why a tail-heavy plane is more difficult to land, because the pilot has to use elevator to push the nose down to maintain flight speed.

You might want a tail-heavy airplane for 3d tricks, but first be sure you can land it. To help:

3.Throttle

Do not glide down to landing. Your throttle is a speed *control* and if you set it correctly (about 1/8 on the SHP) it will help to keep your plane at the proper speed on landing, not too fast and not too slow.

If you learn to fly a full-size plane (or learn to fly an RC plane correctly) you will be taught at some point to fly a "stabilized approach". This means that your landing approach is stable, in that it has no time limit. You could start your approach at 20 feet high or 2,000 ft high, and you can fly in this mode as long as you want.

The opposite of a "stable approach" is a "decaying approach"...this is an approach flown without enough throttle or too slowly which has a time limit. The plane is slowing down (because there is no throttle) and the pilot is trying to get it on the runway before something bad happens.

To fly a stabilized approach, put the nose down about 10-15 degrees, use 1/8 throttle or so, and point the airplane at the spot you want to land. Start high enough and far enough away that you get a chance to fly a stabilized approach down to the runway. Don't "flare" or do anything else until you are very low. If you cut the throttle and pull back on the stick, make sure you're only ankle-high. Too many pilots want to have a dramatic flare at the end of their approach...leave that to the experts. Just fly down to the ground and close the throttle for the last foot or so. Done.

4.Elevator

The elevator is the important control for landing. DO NOT land on 3D rates. Use your low rates. First, fly a pass down the runway about 2 feet high on low rates at about half throttle. Can you do it? For most of us, probably not. Lower your low rates and increase your low rate exponential until you can smoothly fly just above the runway consistently and smoothly. When you are flying a stabilized approach, having the correct elevator repsonse will allow you to actually pilot the aircraft in a straight line, rather than fighting a bucking bronco. Get your elevator repsonse right!

5.Observe

Watch people who can land. Watch people who cannot. See their habits.

What we do not want to do is to go up really high, cut off our motor, and dive at the runway, then pull up and glide along the runway, bouncing up and down, hoping to be able to smack the runway on a lucky bounce.

Instead, we select low rates, select low throttle, point the nose 10-15 degrees down toward the end of the runway and fly a smooth straight line. When we are very low we cut our throttle and bring the aircraft to level and let it touch down.

If we mess it up, we make any necessary repairs, change our CG or transmitter as needed, and try again. Once you know how to land, your repair bills go way down.


Remember that the 10-15 degrees nose down is for your approach. You don't impact the runway at that angle. With a shallow nose down condition you should not be picking up a ton of speed. This isn't a dive at the runway from 400 feet up. You should have already scrubbed off a lot of speed and altitude before you start the descent to the runway.

Make sure to level out above the runway (ankle high). Leveling out too early is better than leveling out too late. Get some practice, progressively leveling out lower and lower with less speed each time but still above stall speed.

Something that helped me a lot was flying "ankle high" up and down the the entire length of the runway at various speeds trying to get it slower and slower but still stable. Then you can get a feel of at what speed the plane will stall out. When you stall out at ankle height then there isn't going to be any damage to the airframe. You will go "WOW, I landed unintentionally and it was a beautiful landing ".

So there is nothing to worry about. Once you get enough practice at that the next thing you discover is that you can cut the throttle at any time you want at that height and pick where you land.

The key is getting low enough, far enough out prior to reaching the threshold of the runway. That gives you enough time to lose any excess speed and touch down.

Keeping the plane nose down and then level once you are just above the runway keeps me from having my throttle set too high.

I used to have a lot of problems with coming in nose up. The throttle setting is much higher. When I get too slow and start to stall, the instinct is to apply more throttle and it is easy to overshoot and pop back into the air (especially when you are releasing elevator at the same time). The right thing to do at that time is go around. Correcting a pop up usually results in porpoising from over controlling and a hard or crash landing.
Very informative and thank you.
TruSpeed is offline Find More Posts by TruSpeed
Reply With Quote
Old Aug 13, 2011, 03:30 PM
Registered User
jeb6684's Avatar
United States, PA, Gettysburg
Joined Mar 2011
346 Posts
Thanks

All these replies have been very informative, thanks. I'm going to try some of these techniques when I go fly a little later.

I think alot of my problem is coming in to high without enough speed, resulting in stalls most of the time. I need to learn a nice long and low approach.
jeb6684 is offline Find More Posts by jeb6684
Reply With Quote
Old Aug 13, 2011, 04:35 PM
Off we go.............
SabreHawk's Avatar
Seattle, WA. USA
Joined Jan 2006
3,325 Posts
Indeed, "Stick and Rudder" should be mandatory reading for anyone who flies a plane, full scale or model.
It will be the best 20 bucks you ever spend in the hobby.
SabreHawk is offline Find More Posts by SabreHawk
Reply With Quote
Old Aug 17, 2011, 09:41 PM
Cessna 25T clear for departure
justindh's Avatar
United States, TX, Houston
Joined Mar 2011
217 Posts
Quote:
Originally Posted by W.W. Corrigan View Post
At the end of the day realize that controlling the dynamic forces acting on an airplane to create the perfect satin smooth finish to a flight is a challenge that will humble you for as long as you fly and some days will just be better than others.
...
...
...

For further reading I suggest for the umpteenth time "Stick and Rudder"

Steve
Great write-up and +1000 on Stick and Rudder. Less than $14 at amazon. It was easily worth a couple hours of flight instruction and flying. I may read it again this weekend.
justindh is offline Find More Posts by justindh
Reply With Quote
Old Aug 17, 2011, 09:55 PM
Registered User
jeb6684's Avatar
United States, PA, Gettysburg
Joined Mar 2011
346 Posts
I just ordered Stick and Rudder. Looking forward to reading it.
jeb6684 is offline Find More Posts by jeb6684
Reply With Quote
Old Aug 18, 2011, 02:11 AM
mostly newbie
shimniok's Avatar
United States, CO, Centennial
Joined May 2011
263 Posts
just got my copy b/c of this thread. am plowing thru a little at a time
shimniok is offline Find More Posts by shimniok
Reply With Quote
Old Aug 18, 2011, 10:40 AM
Cessna 25T clear for departure
justindh's Avatar
United States, TX, Houston
Joined Mar 2011
217 Posts
Quote:
Originally Posted by shimniok View Post
just got my copy b/c of this thread. am plowing thru a little at a time
Packed my copy for my weekend out of town. I think i'll read it again.
justindh is offline Find More Posts by justindh
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Tank Hobby Radio / Transmitter Ideas, Tips, Tricks mfpage RC Tanks 4 Sep 10, 2011 06:41 PM
Question eflite Mcx tips and tricks? mycrors4 Coaxial Helicopters 37 Aug 09, 2011 08:14 AM
Question eflite Mcx tips and tricks? mycrors4 Micro Helis 3 Jul 11, 2011 01:02 AM
Discussion Generic RC Video Editing Software Tricks Tips and ISSUES jims123 Aerial Photography 128 Jul 10, 2011 10:14 PM
Discussion Glow Toledo Special Tips and Tricks Steverc123 Fuel Plane Talk 13 Apr 03, 2011 10:42 PM