Stumped

[Colin McRae]

I was wondering if modelers might offer an opinion concerning the control surface reaction on my Vector 40.
I did not build the model but purchased it from a guy. It is a professionally built model. Definitely not an ARF, but either from a kit or scratch built. But not really sure.

But I notice (on the bench) that when I pull on either lead, and then relax the pull, the control surfaces (both flaps and elevator) the surfaces relocate back close to neutral. Sort of a 'springy' feel in either direction. It is almost like there is a spring on the bell crank tied back to neutral. The controls operate smoothly, and I don't notice any obvious signs or internal binding.

I really can't see into the wing or fuselage. Might anyone know what might be going on? It sure is strange.

Thanks in advance.

[Steve Helmick]

What sort of hinges are used? I'd wonder if they're the R/C type flexy hinges. They're reportedly not good for CL, and I agree 100%.  Steve

[Colin McRae]

What sort of hinges are used? I'd wonder if they're the R/C type flexy hinges. They're reportedly not good for CL, and I agree 100%.  Steve

They are nylon hinges similar to Dubro. There is also Blenderm seal tape on the hinge line gap. Not sure it is the tape because the spring action is in both up and down motions. But it might be. The tape is continuous across the hinge the entire length of the surface. I normally stop the tape on either side of the hinge.

I will remove the tape to see the effect. Then I can reapply new tape.

[Colin McRae]

Problem solved. It was the Blenderm hinge line tape after all. I removed the old tape and problem went away. The model builder used a continuous piece of tape the entire length right across the hinge itself. The tape was stuck to the hinge barrel with no type of slot or anything.

I just have to re-tape correctly.

Sometimes the simplest things!!

[Brett Buck]

Problem solved. It was the Blenderm hinge line tape after all. I removed the old tape and problem went away. The model builder used a continuous piece of tape the entire length right across the hinge itself. The tape was stuck to the hinge barrel with no type of slot or anything.

I just have to re-tape correctly.

Sometimes the simplest things!!

  The technique for this is pretty important, you want the tape to cross the gap in line with the hinge pins, *not* to stretch and relax, or accordion-fold, or it will do exactly what you found.

   I seal over the hinges. I put oil on the barrel so it will slip and don't have any issues. I used to go between the hinges, but at some team trials, I was talking to Paul Walker and he said he could tell the difference. I was skeptical, but, sure enough, even the little 1/16" gaps from the end of the seal to the barrel of the hinge made a small but detectable difference, and when I replaced them with a single piece over the barrels, a few little trim glitches here and there went away.

     Brett

[Colin McRae]

  The technique for this is pretty important, you want the tape to cross the gap in line with the hinge pins, *not* to stretch and relax, or accordion-fold, or it will do exactly what you found.

   I seal over the hinges. I put oil on the barrel so it will slip and don't have any issues. I used to go between the hinges, but at some team trials, I was talking to Paul Walker and he said he could tell the difference. I was skeptical, but, sure enough, even the little 1/16" gaps from the end of the seal to the barrel of the hinge made a small but detectable difference, and when I replaced them with a single piece over the barrels, a few little trim glitches here and there went away.

     Brett

Thanks Brett. I am basically a sport flyer but working away on the pattern. Not sure I will ever compete but who knows. Still have a long way to go. But I do want my models to fly as good as they can. I have been taping my models, but no tape across the hinge itself. I probably would not notice the 1/16" gaps in the air at my skill level. But continuous tape with oil at the hinge is also easy to do.