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Old Oct 27, 2012, 01:58 PM
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rogue wolf's Avatar
United States, NJ, Newark
Joined Aug 2012
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Quote:
Originally Posted by Rockin Robbins View Post
That's not necessarily true. If you establish a flying height of an inch above the ground and reduce throttle you will land without bounce, provided you don't fly back upward again with up elevator. Even then it wouldn't be a bounce, it would be a touch and go!

Bounces happen because of too much vertical velocity when you touch down, not because of too much horizontal velocity. Therefore a bounce-free touchdown can happen at any velocity at which the plane has a sink rate instead of a climb rate.

I prefer to speak in general. Nevertheless, the major point, as stated by the thread title, was how to eliminate landing bounce. That is best accomplished with a proper appoach more than any one factor.
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Old Oct 27, 2012, 02:32 PM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
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Quote:
Originally Posted by jasmine2501 View Post
You can also tie the wheels together to prevent them bending outward.
Ding! Ding! Ding! Ding! A great answer which was the fix for my Slow Stick. And that's one reason the low wingers don't bounce so much. They tend not to use springy wire landing gear with the wire on an angle that induces bounce.
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Old Oct 27, 2012, 02:38 PM
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Canada, BC, Port Coquitlam
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Originally Posted by itsme2 View Post
I am frequently getting a significant bounce on my landings. This is happpening with my Apprentice trainer (tricycle gear) and several float planes that I have. What might be the main cause(s) of this happening? Thank you.
The simple answer to this question is to touch down at the correct airspeed with the perfect flare executed at exact altitude. Of course, this is easier said than done.

There are at least two ways a plane can bounce:

1. descending at a rate that will cause the landing gear/rubber wheels to act like a spring to bounce the plane. Try dropping your model from two feet high and it will more than likely bounce. Model airplane landing gears do not have shock absorbers to damp the "bounce".

2. the wings still have a lot of lift remaining, considering both airspeed and angle of attack, such that any touch down that is less than perfect...meaning too high airspeed or too fast rate of descent (not enough flare), will induce a bounce.

I think ground effect, wing loading and aircraft type interact.

For example, I have a difficult time making perfect landings with my SuperCub no matter how smooth the flare, yet my FMS 1100 Hellcat can literally be plopped onto the runway with hardly a bounce.

If you land at just about stall speed (for your particular model) and give the proper amount of flare at the exact altitude from the ground, there is no reason for any airplane to bounce. Once you understand the aerodynamics and physics of why a plane bounces, all that remains is for you to know what your airplane "wants".
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Old Oct 28, 2012, 04:59 AM
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Joined Oct 2012
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I fly full size and models and the way to land a low wing loading plane like the apprentice is this:
Cut power on final approach,
keep it slightly above stalling speed at a safe gliding attitude,
at 1 ft or lower to the ground level out,
as the model slows pull back the elevator gradually
the model will sink onto the runway (stall)
it MUST stall onto the runway or you are going to fast but you cannot stall too high or you will bounce.
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Old Oct 28, 2012, 11:46 AM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
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Quote:
Originally Posted by GLOW POWER View Post
I fly full size and models and the way to land a low wing loading plane like the apprentice is this:
Cut power on final approach, ...
Are you telling me you cut power on final approach on a full size?

Larry
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Old Oct 28, 2012, 07:47 PM
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Joined Oct 2012
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Quote:
I fly full size and models and the way to land a low wing loading plane like the apprentice is this:
Cut power on final approach, ...
You do cut it dramatically down to almost idle. It also depends on the plane. Light wing loading planes or typical trainer planes you do cut power. but you always stall it onto the runway. VERY IMPORTANT
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Old Oct 29, 2012, 02:03 AM
lost in the addiction of flyin
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Canada, BC, Kelowna
Joined Dec 2009
802 Posts
having taught probably 30 people to fly on apprentices i know the problem your experiencing well. first off yes you need to bring the plane in at a stall like nose high attitude to get a smooth no bounce landing. you will find that you can do this if you time it perfectly with no power on, i dont recomend this method as it needs to be near perfectly executed to be done right. the second way of doing this is to practice low passes as slow as you can do them with lots of up elevator being used in the passes. controlling airspeed and altitude more with your throttle stick than anything. in the 3d world this is known as a high alpha flying style, if you cant get your plane to do this type of attitude try moving the cg back 1/2 inch. Apprentices are designed very nose heavy and the stock cg will actually cause you to bounce landings more than you think. what usually happens it the plane stalls with no power on just at the last second and drops the nose causing it to hit the ground first.

most of all the best thing i can say to you is keep practicing, my students keep saying "man you make it look so easy". i usually reply with "yep 30+ years of practice does that"
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Old Oct 29, 2012, 02:47 AM
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Kilsyth, Victoria, Australia
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I'm surprised that so many say it is "springy" undercarriages that cause the bounce. Having flown a number of Sebart aircraft in both 30 and 50 size I find it the reverse. Sebart undercarriages are relatively rigid but the models are light so any heavy landing, even only mildly
so, will result in a bounce.

A Multiplex Fun Cub with its very springy undercarriage tends to absorb much of the forces either back and forth or up and down resulting in a less noticable bounce.

Different aircraft and different landing choices can require differing approches. Assuming a tail-dragger you really have two choices either "wheeling" the model in or three point landing. Above all you need to appreciate the stall characteristics of that particular model.

If very low stall you can slow the model right down dragging the aircraft in at low speed with the tail slightly down until a couple of inches above the ground you just finally pull the throttle and allow the model to set down at close to zero speed with very little roll out.

A "wheeler" is much more practical with an aircraft that is also a tail dragger but is more heavily loaded and perhaps with a much higher stall speed. At this point the model is flown in still at a lower speed but keeping above the stall speed. When almost on the ground once again the throttle can be pulled off and the aircraft allowed to settle in a near horizontal attitude. The model then lands on the main wheels before allowing the tail to settle controlling the steering with both rudder and elevator. The danger for all of us is to be heavy handed with the elevator as with too much elevator and that increased speed the model is likely to bounce with even a mildly heavy landing. This is where a lot of problems occur because now the model is several feet up and at near zero speed and the likelyhood of a tip stall.

Nose wheel models are as easy to land as tail draggers and if the same rules as above are followed the aircraft can be landed either on the mains or on all three wheels as a matter of choice.

It is always worth practicing stalls at altitude to see exactly how your specific model performs. Once you have tried at stalls height for safety try those stalls at a lower altitude where you can really see what the aircraft looks like and simultaneously judge the speed.
Remember too that the landings will appear to be different if the weather is windly or calm. I say appear because in reality the model is "seeing" the wind speed not the relationship to the ground.

It is not easy to get landings perfect but a good one is truly worthwhile and give great satisfaction. Too many assume that both take offs and landings are just getting off the ground and arriving. In truth they are worth as much as a aerobatic manuever.
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Old Oct 29, 2012, 02:47 PM
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I was just practicing with my Fun Cub this morning. Low speed fly bys will get you used to the plane you are flying. One of the things I do is hold the elevator too long. It causes the plane to touch and go (IE - Bounce). The timing is very important. Let go of the elevator stick as the plane touches the runway or water. It will stick. As said above, Practice, Practice, Practice.
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Old Oct 29, 2012, 03:32 PM
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United States, AZ, Mesa
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Quote:
Originally Posted by DaveBart View Post
I was just practicing with my Fun Cub this morning. Low speed fly bys will get you used to the plane you are flying. One of the things I do is hold the elevator too long. It causes the plane to touch and go (IE - Bounce). The timing is very important. Let go of the elevator stick as the plane touches the runway or water. It will stick. As said above, Practice, Practice, Practice.
I don't know... with my Seawind, I let it touch down when I'm at full elevator speed, then I can hold the elevator to slow it down - I do that with a lot of planes. If you're going fast enough at touch-down that up elevator causes the plane to take off again, you're going too fast.

That brings up something I didn't mention before - there's two kinds of bounces - one is an actual bounce, from the spring tension in the landing gear - the thing I'm talking about is when the plane starts flying again, and to prevent that, you need to be holding full UP elevator when you touch down. If the plane can descend with full UP elevator being held, then it absolutely will not take off again, because it can't.

The way to prevent the other kind of bounce is to reduce your vertical speed, and you may need to maintain some horizontal speed to do that. So, you need to look at your problem and decide what it is - the solutions to both issues have been given, and they aren't a matter of opinion. We are talking about laws of physics here.
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Old Oct 29, 2012, 03:49 PM
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Canada, BC, Kelowna
Joined Dec 2009
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there are times when with the apprentice i land at full elevator and never release it all the way in even when taxiing, you need to have the plane fully rotate to a nose high attitude before the wheels touch the ground if the plane falls out of the air before you touch down you need to give it a couple of clicks of throttle. always think of it as your doing a three point landing on a tail dragger and you will never bouce again. if the plane balooons when you feed in the up elevator your still to fast if the plane rotates and slowly mushes in you have the right trottle setting, if the plane almost stops in the air and drops the nose your to slow. learn this at some altitude and find out what throttle setting you need to have it just mush in. once you find that magical point you will rarely bounce the plane again.

doing this works for all planes, learning this for each plane is needed as not all planes stall the same. a less stable plane than the apprentice may drop wings when stalled you need to learn this at a highter altitude for this reason.

and as i stated earlier practice practice practice. there are days still when i just sit there and do figure 8 touch and goes for the whole flight, making a landing look perfect is a real joy sometimes.
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Old Oct 29, 2012, 09:10 PM
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How to eliminate landing bounce? Land the right way - on its belly!
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Old Oct 30, 2012, 12:53 PM
DX5e fatal flaw- PM me!!!!
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I found my tendency was to pull up on the elevator as I approached the ground, flying towards the ground just felt too unnatural. This of course led to a stall (only from 6 inches or a foot, so not crash-inducing) and a big bounce.

There are at least 3 ways to land, and they all work, and if someone tells you one of 'em just isn't 'right', they're wrong. There may be wrong times or places or planes for a particular type, but if you land smooth, stay on the runway, and keep it planted after it's down, it's a good landing. For a high-wing trainer with trike gear, any of these 3 ways will work.

- you can fly at the ground and kiss it at speed, looks nice but you have a very high rollout speed. Also, if you goof up you are going fast, and stuff's gonna break. I don't really recommend this method, but in gusty winds it can be a lifesaver.

- You can come in with low power with the nose at the ground, carry a little speed, then use the elevator to bring the nose up, level off, bleed speed, and keep cranking in elevator until it stalls, all with the wheels just off the deck. Keep enough speed such that if the wind slacks off you still have enough airspeed to keep it flying. The tough part about this method is 'energy management'. Go google "energy management" "bob hoover". Go. Now. Do it.

- You can come in with the nose level or a little high, whatever is required to keep the plane above stall speed by some margin, yet have the plane descending without the nose pointed down (or only a very little). Idea here is the elevator sets the airspeed of the plane, and the throttle controls the altitude. You descend and as you get just above the runway you add some power to arrest the descent, and fine-tune the power such that you gently settle on the runway, then cut power. This is the most realistic method, and takes a bit of skill, and is what most would consider the 'best' method. It's the most fun, in any case.
For this method I suggest practicing at some altitude, and finding a descent speed you can use on your approach, and to find a flight speed at which the controls don't get mushy (ailerons usually go first).
With this method if the wind slacks off you must add some power fairly quickly, this method is closest to stalling speed.


Now obviously you can mix and match amongst these methods, but the idea is to build confidence and experience by using a method that minimizes how many controls you need to focus on.

The throttle method, you focus mainly on the throttle, and the nose-down carry-some-speed method you are focused on the elevator.

Once you can do all 3 of these methods you will find yourself picking pieces of each to deal with different situations and all the myriad ways to screw up, and goosimng the bthrottle and managing the elevator simultaneously.
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Old Oct 30, 2012, 01:21 PM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
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That's the difficulty with a thread like this. Every plane knows the kind of control inputs it likes to eat. Feed it what it likes and it's happy. Otherwise, not so much.
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Old Oct 30, 2012, 06:21 PM
DX5e fatal flaw- PM me!!!!
United States, NY, Cortland
Joined Sep 2010
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Like my WWI bipe- fussy bugger on landings. Undersize ailerons don't help (much smaller than scale)
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