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consistency

Old 06-20-2009, 10:48 PM
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maerlma
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Default consistency

i was at the field today and some of the usual guys that i fly with weren't there. i didn't mind, though, because i met some of the other guys in the club who usually fly on different days than me. the wind was marginal today, though it was straight down the runway. my first flight i made a beautiful wheel landing, setting down gently on the mains first, then the tail settled as i bled off speed. my second flight, though i had trouble getting it down. i was flying the same pattern, and did my approach the same way, but i ended up making one of those ugly, bouncing landings. maybe the wind had picked up a little for the second flight, i was having trouble getting the plane on the glide slope. it kept wanting to balloon up and quickly lose airspeed on final, so i was putting in a touch of down elevator, trying not to dive toward the deck. what was i doing wrong? i hope i'm not tail-heavy, but after i got the plane all setup the cg was right where the instructions said it needed to be and i haven't changed anything.
Old 06-20-2009, 11:27 PM
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JohnW
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Default RE: consistency



Assuming the plane lands fine in clam conditions, I'll say you were too fast for your trim based on the wind speed you mentioned was higher than what you are used too so you probably flew your approach at higher speed to create the same illusion of glide slope, the balooning, and needing down elevator.  I assume a flat bottomed or semi wing?  Try adding a touch of down elevator trim and be aware that in a head wind the approach will/should look slower.

Old 06-21-2009, 12:25 AM
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WestCoastFlyer
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Default RE: consistency

Imagining your description, both landings seem a little hot. The first landing sounds like a "Fly it to the deck" as the Navy teaches.

A better landing in RC is a stalled landing. The idea is to stall the airplane as you touchdown. Depending on the airplane, this involves slow and steady flair the last couple of feet - depending on speed, wind and the airplane, which all change for every landing.

The second landing sounds like you came in too hot and tried to bleed off, then gain speed with the elevator. I think you should watch how similar airplanes to yours land. You mentioned a "glide path," but that could be anything. You could be too high when you turn on final. Watch for the height of those other airplanes like yours on final. Also ascertain how much throttle they have on final, because you may be carrying too much speed.

Old 06-21-2009, 06:29 AM
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jester_s1
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Default RE: consistency

If you're getting balloning that's just simple pilot error. Go easy on the up elevator and let the plane settle in. Bounces usually indicate that you stalled your wing by losing too much airspeed. That's common on windy days. You can save a bouce landing by goosing the throttle after the first bounce, giving yourself some more airspeed to work with. On windy day landings, leep a little bit of power on until your wheels touch. When the wind is high, you actually have to fly the airplane all the way to the ground with the power on, setting it down with the sticks.
Old 06-21-2009, 08:27 AM
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Default RE: consistency

I remember something similar happened to me once.
The rubber bands of the wing were old and let the wing lift up and shift enough after a couple of aerobatics as to change the AOA and decalage (difference in AOA between wing and tail), making the model float forever.

If the wind just picked up a little bit, the difference in behavior may has not been caused by it.
Old 06-21-2009, 09:21 AM
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Default RE: consistency

That "touch of down elevator" is what you were doing wrong. You lose altitude on final by cutting the throttle. If you try to lose altitude with down elevator, your airspeed will increase and when you level out, the plane will climb because of that increased airspeed. You should fly your whole final approach with the nose just a little high. Throttle controls rate of descent: less to come down faster, more to climb.
Old 06-21-2009, 09:56 AM
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Default RE: consistency

The best approach you can make on landing any aircraft is one that you cannot see the bottom of the aircraft, yet it flys straight.  That means no down elevator and carefully adjusting throttle to slow down the aircraft.  If you do it right, the plane will slow down and descend on it's own.  Once ready to land, the flair maneuver in which you pull a little elevator to raise the nose slightly will bleed off the remaining airspeed and it will settle in for a nice smooth landing.

You can force it down if you wish, but your landings will most likely bounce or be very hard which is the best way to break things.

I preach this all the time whenever a thread like this one comes up.  Practice is the best way to do things right.  Dedicate a flight, perhaps the first one of the day, to doing nothing but take off, trim, then do approaches.  You don't have to actually land, but get it to a point where all that is necessary is to flair and land.. then simply add throttle and go around.  Get the plane to go where you want it to go and practice that technique. 

Make the turn from base to final and point it right at you, and reduce throttle and watch it.  If it appears to be short, ADD A BIT OF THROTTLE and then remove what  you added once you are back where you want it.  MOST important, if it does not look good, by all means, go around.  Don't try to land it at any cost because what you will most likely end up with is a broken plane.  Don't be so proud that you don't want to go around.  A better pilot will see the problem, add throttle and climb out and go around and try again. 

Practice.. practice.. practice.  Burn fuel.  Get that thing up there, and do practice landings.  That's the only way you will get it right.  Eventually, your landings will be the envy of the airfield.  Then you will have consistency in your landings.. they will look good and will get you to your next flight rather than picking up the pieces and going home.

CGr.
Old 06-21-2009, 12:05 PM
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Default RE: consistency

top gun is correct...throttle does not control speed on approach...elevator does......throttle is altitude......a bouncy landing is not a stalled landing...a bouncy landing is too fast and not enough up elevator.....a stalled landing is a splat landing where the airplane falls onto the runway.....if your descent rate becomes too great goose the throttle..2 clicks up and right back off again..this will retart the sink rate
Old 06-21-2009, 12:13 PM
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Default RE: consistency



Right.  If you want to extend your landing approach, add a little throttle.  That will level out the aircraft and extend the approach.  Then when ready, remove what you added and continue the approach.  "Altitude" may mean maintaining altitude rather than descending.  Same as Topgun and Jetmech said.  So, you are 30 feet up and coming in but you are short.  Add some throttle, the plane will level out (maintain altitude) until you are where you want to be, then remove what throttle you added and the plane will slow down and continue to descend. 

CGr.

Old 06-21-2009, 12:36 PM
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Default RE: consistency

Following the above advices, you will not be able of landing without consistency.

Then, crossed wind landings will be easier to master.

Use rudder to correct alignment rather than aileron, especially when approaching too slow.

Use rudder side to side also to bleed off excess of approach speed.

A bouncing landing is always a landing at excessive speed (too much energy, able to flex the landing gear enough to make it react like a spring).

A crashing landing due to early stall is always a landing at insufficient speed, mainly forced by up elevator at final.
Old 06-21-2009, 03:57 PM
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Default RE: consistency


ORIGINAL: lnewqban

Following the above advices, you will not be able of landing without consistency.
Might I ask why? (or why not)?

It seems that you pretty much repeated what we've been saying, then adding some rudder info.

CGr
Old 06-21-2009, 05:18 PM
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WestCoastFlyer
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Default RE: consistency

ORIGINAL: CGRetired
ORIGINAL: lnewqban
Following the above advices, you will not be able of landing without consistency.
Might I ask why? (or why not)?

It seems that you pretty much repeated what we've been saying, then adding some rudder info.

CGr
CG, he's saying the same thing but using a double negative.

Maerlma, Top_Gunn wrote perfectly what I and many others on this thread were trying to explain. Top_Gunn wrote, "If you try to lose altitude with down elevator, your airspeed will increase and when you level out, the plane will climb because of that increased airspeed."

Old 06-21-2009, 10:22 PM
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Default RE: consistency


ORIGINAL: CGRetired


ORIGINAL: lnewqban

Following the above advices, you will not be able of landing without consistency.
Might I ask why? (or why not)?

It seems that you pretty much repeated what we've been saying, then adding some rudder info.

CGr

Sorry, CGRetired, my statement was confusing.[]

I just tried to use the word that made the title of this thread: Consistency.

I agree with all you guys stated above, which is great advice.

Regards
Old 06-22-2009, 09:52 AM
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maerlma
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Default RE: consistency

thanks for all the replies guys. i guess i just need to practice more. i was a little nervous about slowing down too much because i've just removed the droops on my pts mustang, and the wind gave the illusion of being too slow.
Old 06-22-2009, 11:08 AM
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Default RE: consistency

You should get some altitude and keeping the nose from falling, stall your aircraft, get the feel for the stall....
now on approach you'll have a better idea how your plane will feel.....watch for the controls to become sluggish or the tail to droop......
Old 06-22-2009, 11:11 AM
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Default RE: consistency



If you do some high level approaches, you can work the throttle and see where you are losing perspective.  You can slow it down to where you feel is what you want and see how the plane reacts.

One thing I've done is climb way up high, where you have time to recover, point it into the wind, and drop the throttle to idle and see what happens.  If it still flys, meaning if it is still moving into the wind, you know what you can do at idle.  If it stalls, add throttle and recover, then do it again, this time with a little more throttle.  That way you can gauge your throttle for what you can expect during conditions such as are at altitude. 

Each landing is going to be different, but the process is the same.  You have to watch and work out in your mind as to how the aircraft appears during your approach.  At some point, it will come to you automatically and you will just do what is necessary, FOR THAT PLANE, to land it correctly and safely.

It's always good to work things out about "three mistakes high" 



CGr.

Old 06-22-2009, 11:12 AM
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Default RE: consistency



Now that was interesting, Jetmech.  We both posted pretty much the same thing at the same time. 





CGr


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