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Stop landing "bunny hop"

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Stop landing "bunny hop"

Old 06-22-2015, 05:11 PM
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BillJ
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Default Stop landing "bunny hop"

I've been working with an airplane to try and relieve its very long glide and Bunny Hop tendencies on Landing .....Tonight ..I took a serious look and found that sitting on the gear my Wings have +3 degrees incidence...... I'm thinking that unless you are a super zero airspeed..this is causing the problem...touching the least little bit fast and boom/bounce ...you're still flying....

Is the easiest way to correct this perhaps cutting nose gear strut down to try Lower nose on landing below + incidence on touch down ?

Appreciate the inputs

Bill
Old 06-22-2015, 05:20 PM
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gunradd
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Crow and lower landing speed will help. The crow I think will be the key.

Also what kind of plane is it? Are you running the brakes on down elevator? it helps to hold up elevator through out the landing.
Old 06-22-2015, 05:26 PM
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DAN AVILLA
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It would be good if you stated what plane you have. As a example many planes will not land fast. You need to be at stall and never let off the elevator or you are along for the ride. Crow like was suggested works great. Dan
Old 06-22-2015, 05:30 PM
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skylark-flier
 
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What plane, size, weight? A foamie with 3 degrees would probably be a disaster in all cases, my .60 Stratus floats down softly but when she touches the ground she stays.
Old 06-22-2015, 05:59 PM
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noahb
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I had a dv8r that did this. Crow made a huge difference. It had about 6deg. + i extended the main gear and that improved things as well
Old 06-22-2015, 09:07 PM
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invertmast
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anytime i've seen the bunny hop, its almost always b/c of too high a landing speed..
Old 06-22-2015, 09:30 PM
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LA jetguy
 
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Crow definitely helps... Also try applying some brake "before" landing, it will take the energy away on touch down and pull the nose down. Once you touch down you can then release the brakes and pulse them...

Check the CG as well. A little nose weight prevents hopping.
Old 06-22-2015, 10:08 PM
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paulsf86
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Make sure the cg is correct. Too nose heavy results in fast landings and almost always increasing amplitude bounce as the airplane goes down the runway helplessly. Crow certainly helps but getting the airplane set up correctly is the first step.
Old 06-23-2015, 12:01 AM
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Trailing link UC can cause this when the springs are worn and too weak to stop the sudden increase in incidence (more than 3 degrees when loaded)! It can be much improved by binding the spring and leg together with about three layers of electrical tape (as a test) if you are using this type of leg!
Old 06-23-2015, 04:32 AM
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JohnMac
 
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Originally Posted by invertmast
anytime i've seen the bunny hop, its almost always b/c of too high a landing speed..
I am with inverstmast on this one, too much speed on touch down relaunches the model into the air but without enough airspeed for good control. Don't hurry your landings, hold off until the model can't stay airborn any longer. The trick is to do this about 2" off the deck.
John
Old 06-23-2015, 06:49 AM
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dionysusbacchus
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When it's done flying, it won't jump off the ground anymore!

https://www.youtube.com/watch?v=UgYYK35GlOY
Old 06-23-2015, 08:40 AM
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Zeeb
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As others have mentioned, you need to get the thing slowed down and adding crow to the flaps on approach will help on lots of models. It's helpful to remember that an aircraft, full scale or model, will fly slower than it will glide and this is called "slow flight". It's accomplished by increasing the angle of attack (AOA) and sustaining flight by adding power. This is what you want to do on landing; slow flight, control the descent rate with throttle not elevator and let that puppy settle in nose high and slow just like the video above although I'm not big on a full elevator deflection.... Also, setting up for landing while carrying some power will decrease the spool up time if you need to go around as the engine is already running at a higher RPM. IF you do bounce one, IMHO the only option is to go around as you'll usually wind up with what's known as a "porpoise" and unlike some maneuvers where it will settle down, a porpoise as you've found out will only get worse if you try to go ahead and land.

JMHO
Old 06-23-2015, 08:54 AM
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FalconWings
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BOTTOM LINE: you are landing too fast. Everything else is just a contributor leading to......
Old 06-23-2015, 08:59 AM
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dionysusbacchus
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I only use full up elevator on certain models and in this case with the F-18F, it was just showing off, but it is more than capable. On many models I can hold full up elevator all the way down the runway controlling altitude with throttle, this is the key to landing exactly where you want to land, I can land at my feet 95 percent of the time.

Throttle controls altitude and elevator controls airspeed on landing, when you figure that principal out, you will land like a pro.
Old 06-23-2015, 09:01 AM
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Greg G
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One other tip is to make sure you have enough elevator authority to keep the nose high at just above stall speed at touch down. I use HIGH Elevator Rate for landing only.

Also, with the high angle of attack and full flaps there will be significant drag that will continue to decelerate you if you have insuficient power (thrust). In landing configuration I carry 15-25% power until very close to touch down. At a few inches off the deck keep pulling more up elevator until she can no longer fly. With proper balance and enough elevator authority you may be able to keep the nose gear off the ground while rolling on the mains.

It's easy to fly from the keyboard! There is no substitute for practice.
Old 06-23-2015, 11:19 AM
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Softer spring in the nosewheel will help. The rule is to have softer in the nose than mains.
Old 06-23-2015, 01:53 PM
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Bill
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Old 06-23-2015, 02:04 PM
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basimpsn
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F-18 with never bunny hop.. the main sit too far behind the CG.
Old 06-23-2015, 02:45 PM
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Originally Posted by basimpsn
F-18 with never bunny hop.. the main sit too far behind the CG.
True, and nothing will bunny hop if your plane is set up right and you use proper landing technique, I also have a BVM Bobcat. My F-18 video was for the illustration of my technique that is true for all airplanes.
Old 06-23-2015, 03:47 PM
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highhorse
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Getting back to the original question: Yes, shortening the nose strut will help a lot.
Old 06-23-2015, 08:40 PM
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gsmarino2000
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I have not noticed that a longer nose strut makes any difference at all. Landing too fast can do it every time.

Greg
Old 06-23-2015, 09:11 PM
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This is a good discussion topic as I think many people have had this problem, especially when transitioning to a heavier loaded model like a jet... I know I did, and did a bit of damage to my Bandit until I got the landing sorted.

I’m with Invermast and Falcon wings Dan Avilla, Gunradd, Chris etc.. Bouncing or hopping on landing is mostly because you are touching down too fast. Crow, Flaps, speed boards, and rearward CG can all help to slow down..
Old 06-23-2015, 11:00 PM
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You need to be at stall and never let off the elevator or you are along for the ride.
Old 06-24-2015, 06:01 AM
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Too high landing speed is not neccessarily resulting in bouncing. Sinkrate and aircraft pitch are also important factors. I have witnessed multiple bouncing even at stall speed. If the model hits the tarmac too hard, and the nosewheel spring is hard as/harder than the mains, the next result will often be an exessive nose up attitude.....and the show begins. I have had silly high speed landings after flame-outs, wanting to land at the runway. They were not bouncing even if the speed was too high. Many nosewheel struts are delivered with the same spring as the mains, so I change or cut down the nosewheel spring.

edit: that said....correct speed is best

Last edited by kimhey; 06-24-2015 at 06:12 AM.
Old 06-24-2015, 06:48 AM
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BillJ
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Well, Quite a discussion ....My Kudos to Dan Avilla and Zeeb for asking a very important question and bring up good points...Point well taken from Kimhey as well ..And of course JOE in Ohio,,who has the inside scoop


Lots of good ideas her that will be real helpful to folks down the Google search line.... As far as my issue..I'll let you know of the changes and effect with a post here
Bill

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