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General control line discussion => Open Forum => Topic started by: Joe Yau on February 04, 2008, 11:21:28 AM
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I'm just wondering if thats a good idea to put in? (if you hold the wing flap, the elevator could move up to 1/8-3/16") I think its suppose to help stabilize level flights.
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That is something that has been used in the past (and maybe some still do!), but I think it has pretty much fallen from favor. ?? ?? ??
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The practise was favored back in the day when we could not easily make adjustments. It still works, to some degree, but it's far better to build in accurate incidences, and use the adjustable features to settle in the best trimming so that slop is not needed. H^^
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The practise was favored back in the day when we could not easily make adjustments. It still works, to some degree, but it's far better to build in accurate incidences, and use the adjustable features to settle in the best trimming so that slop is not needed. H^^
Didn't want to go too far out on the limb, John, but I haven't done it in over 15 years........ ;D
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What do you notice when its not quite right? I have experienced on one of my planes that when its right side up it flys fine, but when it goes inverted its very twichy.. like its hunting a bit.
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Just went through this.. Couple things you will notice if the flap to elevator link is too short or too long. Unequal inside and outside turns and/or the airplane trying to seek a flight level too high or too low.. Most noticeable when inverted.
In my case the airplane wanted to fly upright at two feet and inverted at 12 feet. Thanks to an adjustable push rod (clevis) a little up elevator easily fixed it. Slop might have made it better but adjusting the pushrod length to get the flaps and elevator agreeing with each other is the right solution. Of course this is assuming the airframe is reasonably straight to start with.
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I have heard the reasoning behind the slop in the elevator horn is to compensate for weather changes. The airplane changes shape/size when the temperature and humidity levels change.
Hunting is sometimes cured by slop, along with a little down elevator or built in incidence. Slop or no slop, both have prooven to work.
Mike
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I usually put just a bit of slop in the elevator horn. I will ream out the hole on the horn just a tad (that's the precise technical measurement I use) with a Dremel tool. I do use an adjustable ball link system, but still keep just a bit of slop. This does seem to help keep the plane from having any characteristics of hunting while in level flight.
Later, Steve
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"Slop" works to stabilize a hunting plane, yes, not sure anyone understands why...I used to resort to it to smooth out a jumpy Rat racer. The big problem with "slop" is that it increases with time...the pushrod moving in an oversize hole tends to wallow it out even more, ultimately it will wear through. OK if it's exterior where you can keep an eye on it.
--Ray
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I've just been really lucky (or dumb). I don't remember having a plane (since I have been flying in competition) that *hunts*. ?? ?? ?? ??
Of course, now my very next one will!
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In my case the airplane wanted to fly upright at two feet and inverted at 12 feet.
That sounds sort of like what it was doing right now, maybe i'll try a hair up on the elevator and see if it smooth out or not.. before i get into putting slop in the elevator.
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That sounds sort of like what it was doing right now, maybe i'll try a hair up on the elevator and see if it smooth out or not.. before i get into putting slop in the elevator.
HI Joe
If your plane is built straight, you will most likley be better off with a little down in the elevator, not up. I would try that first
Randy
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HI Joe
If your plane is built straight, you will most likely be better off with a little down in the elevator, not up. I would try that first
Randy
Agreed in most cases the end result will be a little down elevator in reference to the flaps but depends on how much down it had when it came off the bench. In my case I had too much down cranked in and had to go up. If his airplane is trying to climb inverted he needs to go up. Again we are assuming the airplane is reasonably straight and the engine thrust line is OK.
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To really confuse the matter on this, do you make sure you have more elevator than flap movement? On my ARF Oriental that I have just rebuilt the controls. I could hold the flaps and move the elevator a good 1/4 inch each way from neutral. Almost lost the plane several times before I rebuilt the controls. The pushrod was good at the elevator as far as no slop. It was the elevator rod at the flap horn I put a ball link in to get back to no slop in the controls. The plane now flies like it did the first times I had it out. Later, DOC Holliday