Why a Large Elevator Horn Hole Helps Hunting

[phil c]

Hah,  I'll hazard a guess, and not divert the other thread.

If the controls are very tight the slightest bit of down elevator makes the plane dive.  The pilot can't easily hold his hand steady enough exactly where he wants it to be.  Pilot induced oscillation.  If the horn has a slightly oversize hole the pilot can relax the controls to neutral and even put in a slight amount of down, but the elevator won't follow it, if the amount of control is small.  This is in addition to other causes that have been discussed elsewhere- airflow over the stab, the need for a slight amount of down elevator at neutral flap, etc.

[minnesotamodeler]

So the airplane (if well trimmed) is really sorta flying itself.  That somewhat makes sense.  Thanks, Phil.

--Ray

[Russell Shaffer]

I'll go with that.  We might also throw in line oscillation, ground effect, wind, etc.  The pilot's hand is rigidly attached to the ground, not necessarily steady.  The aircraft is anything but.  It makes sense to me to allow a little play in the system.  The lines have some stretch, but unless you are really on the ragged edge this shouldn't make any difference.  A little play in the control linkage should help to compensate for any number of small variations in the flight of a CL airplane.  Speaking for myself, I can use any help I can get. I have fun, but I am certainly no expert. 

[L0U CRANE]

To all three of yuh...

30 or more years ago, the 'received wisdom' included the idea that a bit of SLOP - let's call it by its right name - at the elevator horn improved grooving in level flight. ...Without harming response for rounds or corners. This had been 'discovered' accidentally by someone who noticed that older stunters, in which vibration had egged out the elevator horns a bit, seemed to track better in level flight and straight sides. NOTE: Slop at elevator, no slop at flap, horns...

Since then, we've come up with much larger stab/elevator areas, with much nicer 'fittings' to provide slop-free connections at flap and elevator, and with several top fliers who are death on "slop" anywhere in the controls system. (If it chatters enough to open clearances in the elevator horn, what is it doing to the rest of the control system, and when will it fail 'catastrophically'?)

YES, slop works. ...temporarily. Long-term, I think it 'is/would be' better to have the model trimmed to NOT need it, so that the modern approaches to control hook-ups can do their thing. Vibration caused wear only gets worse as flying time builds up. Isn't that reason enough to build a tight (minimum free clearances) control installation?

[minnesotamodeler]

You're right of course, Lou, that was our experience too--as I stated in the other thread, a guy had to really keep his eye on the elev. horn lest it wear completely through.  I don't think larger stab/elevator even enters in to it; my experience was with a Rat Racer with minimal elevator.  With any size tail feathers the right approach would still be to build it right, build it tight and trim it to fly to your taste.  We used the "slop" as a last-ditch fix to get a few contests out of an otherwise unusable bird.  I wouldn't (and didn't) incorporate it into a standard building procedure. But it DID work when needed; I just always have wondered why...always seemed sort of counterintuitive. 

--Ray

[Bootlegger]

  Fellows this question comes to mind... If the model DOESN'T have flaps, does "slop" in the elevator help or only on flapped models
 Another question, I have used Nylon control horns on profile models and there is no slop, I have to drill the holes larger...

[john e. holliday]

Since day one I have always set my controls up a solid as I could get them and still having them be free from drag while trying to move the surface.   I guess having my planes a little nose heavy has helped the wandering thing.  Of course this past weekend I don't think anything would have helped the planes fly level.  DOC Holliday

[peabody]

I believe that Noel "we have the technology" Drindak covered the idea of "slop" in an article once....and came to the conclusion that slop masks a problem,, and that an accurately built piece needs no slop.....

Real aeroplanes don't have slop......

[Shultzie]

 
Over the years....It boggles my mind....that so many flyers seem to have the ability to train their "MIND TO MUSCLE MEMORY" and by some miracle....seem to be able to fly some pretty amazing and successful patterns with a model so poorly trimmed that would scare the livin' out of even the most gifted aviator.

For example, I had an old modified twin tailed Nobler (nicknamed GOBBLER) that for some reason or another after hours spent trying to get that model de-demonized....
I  finally GAVE UP and just learned to live and fly that old model and actually competed successfully with it. Evem by some stroke of the draw won a couple of pieces of plastic with it???

Gary Letsinger, Joe Dill, Bob Emmett, Ben Madsen, Howard Dooty and others that had the misfortune to test ride that old "GOBBLER!"
 Durng practice sessions....this old weird-terrorized Nobler by Shultzie....in the hands of some of our best local flyers in those days brought some pretty illustrative comments ranging from "LET ME REKIT THIS PIECE OF S--T FOR YOU" to "POUR THAT DUKES FUEL OVER IT,DONATE THIS TO THE BURN BARRELL!"

Gary Letsinger is known for his gift in understanding and  correcting even the most out of trim models...He deemed this old GOBBLER of mine....as "The worst flying Nobler that he had ever had the misfortune to test fly and wondered how anyone could fly a pattern...little lone win anything with it?"

[john e. holliday]

Don,  Do you still have that bird?  Today we have people that I have been told that can fly a plane and tell where it is out of trim.  DOC Holliday

[Shultzie]

Don,  Do you still have that bird?  Today we have people that I have been told that can fly a plane and tell where it is out of trim.  DOC Holliday

I did that model justice....and entered it in a slow combat event....where it was "TERMINATED" by a direct hit right in front of those twin rudders by a Ringmaster, knockin' the entire tail section OFF WITH A BANG!...

(I can still see both that old GOBBLER AND RINGMASTER...FALLING OUT OF THE AIR WITH PARTS THAT LOOKED LIKE AN AFTER-MATCH OF A PILLOW FIGHT!)
  The ski rained airplanes that day in Auburn Wa.