Taping hing lines

[James Mills]

What is the prevailing thought on taping the hinge lines: tape the entire hinge line or tape in between the hinges?

James

[Brett Buck]

What is the prevailing thought on taping the hinge lines: tape the entire hinge line or tape in between the hinges?

James

  Over. I didn't think it mattered, but at the 2005 NATs Paul mentioned he found a difference, and I tried it, and sure enough, it was different.

  That also tells you how critical sealing the hinge is overall - the difference is only a few gaps totaling something like 1/4" of unsealed hinge gap, and yet, the difference was pretty unequivocal.

    Brett

[James Mills]

  Over. I didn't think it mattered, but at the 2005 NATs Paul mentioned he found a difference, and I tried it, and sure enough, it was different.

  That also tells you how critical sealing the hinge is overall - the difference is only a few gaps totaling something like 1/4" of unsealed hinge gap, and yet, the difference was pretty unequivocal.

    Brett

So did he seal the entire hinge line?

James

[James Mills]

So did he seal the entire hinge line?

James

Never mind Brett, I reread your answer, Over.

James

[Motorman]

I've got a Banshee with a good 1/8th flap gap (forgot to recess the hinges). I sealed the whole thing and didn't notice any difference at all except all that tape looked stupid so, I took it all off, still no difference ymmv.


MM

[Phil Krankowski]

I noticed a difference in freedom of movement when I taped over the hinge vs up to the hinge on one of my flite streaks.  I can't fly well enough to tell if there is a performance difference.

Phil

[Mark Scarborough]

you need to prevent the tape from actually sticking to the hinge barrel,,, I use vaseline on the hinge barrel,, when the tape sticks to the hinge,, it will add friction to movement.

[Phil Krankowski]

you need to prevent the tape from actually sticking to the hinge barrel,,, I use vaseline on the hinge barrel,, when the tape sticks to the hinge,, it will add friction to movement.

Now that it is pointed out that is so very obvious!  I will stick with my butted tight to the hinge on both sides for now, but I will consider this for the future.  (It will also make application a little easier)

Phil

[tom hampshire]

     I have found too much friction (stiction?) when taping surfaces with a single strip of tape on both the fixed and movable surfaces.  It is less when the tape is pushed in to the gap with a credit card, but still more than desirable.  One solution is to have the tape stick to the fixed surface only, leaving it free to slide on the movable surface.  Build a tape strip with the rear half covered with a second strip of tape, mastic to mastic.  Trim to finish size with a straight edge and knife.  Apply the open mastic to the fixed surface and allow the blanked half of the tape to bridge the gap between the surfaces.  Of course you need to do both upper and lower sides of each flap and elevator, but if done carefully, you gain a net reduction in friction.  I had no luck trying to build the tape assembly on the airplane.  The half blanked tape needs to be assembled on a clean surface and then removed for application to the fixed surface.  I can't detect any leakage past the unsealed tape, because the application on both sides of each surface works like a pair of facing check valves, allowing no flow irrespective of the orientation of the pressure gradient.

[Trostle]

     One solution is to have the tape stick to the fixed surface only, leaving it free to slide on the movable surface.  Build a tape strip with the rear half covered with a second strip of tape, mastic to mastic.  Trim to finish size with a straight edge and knife. 

 I can't detect any leakage past the unsealed tape, because the application on both sides of each surface works like a pair of facing check valves, allowing no flow irrespective of the orientation of the pressure gradient.

Tom,

Ed Southwick did this and I thought is was a great idea.  It is a great idea and it does work.  I tried this and used it for a while and liked it.  The problem I eventually encountered is that oil starts to collect between the tape and the surface that it is sliding over as the flaps and/or elevators deflect.  That oil is viscous.  If there is enough oil between the tape along the length of the moving surfaces, the controls start to become very stiff.  The solution of course is to meticulously clean the oil between the tape and the surfaces.  For me, this became too much trouble and there was always the risk that the controls would become sluggish during any flight.  I almost lost an airplane because of the resulting sluggish controls.

Maybe you have a way to keep oil from getting between the tape and the moving surfaces.

(I guess electrics would not have this problem.)

Keith

[Phil Spillman]

It is quite possible to accomplish the same objective by building Mono-Coat hinges the entire way across the moving surface! I've done this on several profiles and in repairing an ARF Nobler with a broken barrel hinge. The repair was only that--- a repair the others were an attempt at sealing the joint. This has worked well for me! I have also taped other gaps the old fashioned way which improved my flying!

Phil Spillman

[Randy Powell]

I've had one plane (count them, 1) that flew better without the hinge lines taped. I always fly a plane without first. But almost invariably, the get taped. And generally the entire length. Mark's point is good. Grease the hinges first.

[Bill Burton]

I just use Dacron hinges all the way down the hinge line.  The hinge line is completely sealed.  No tape needed.

BB

[RknRusty]

I sealed the elevator on my Oriental ARF with tape. However I left the flap hinges un-sealed, because I ended up with more flap than elevator deflection. So I guessed maybe a little mush there would be best. However now I'm repairing it after flying into a Dust Devil, and then the ground, breaking all the Dubro pin hinges, among other things. I was all set to stitch new ones since the flaps are still epoxied to the coupler through the fuselage. I'm thinking this Monokote hinge idea might be a good fix, and might as well seal them while I'm at it.

So, is it just 1" wide strips of Monokote ironed together with 1/4" of each other's overlapping glue sides. I'd like to try this.
Rusty

[Bill Burton]

I sealed the elevator on my Oriental ARF with tape. However I left the flap hinges un-sealed, because I ended up with more flap than elevator deflection. So I guessed maybe a little mush there would be best. However now I'm repairing it after flying into a Dust Devil, and then the ground, breaking all the Dubro pin hinges, among other things. I was all set to stitch new ones since the flaps are still epoxied to the coupler through the fuselage. I'm thinking this Monokote hinge idea might be a good fix, and might as well seal them while I'm at it.

So, is it just 1" wide strips of Monokote ironed together with 1/4" of each other's overlapping glue sides. I'd like to try this.
Rusty

Rusty I have used Monokote hinges on several models where the wing was Monokoted and they work well.  Yes that is the way you make them.

BB

[Brett Buck]

I just use Dacron hinges all the way down the hinge line.  The hinge line is completely sealed.  No tape needed.

   The value of sealing them was first discovered, sort of, when people started using pinned hinges (instead of cloth) and found the airplanes flew much differently.

    The reason you do it is more to make the leakage through the gap even between the sides (i.e zero) and at all deflections,  more than it is to make the surface more effective. Although it does that too.

     Brett

[Bill Burton]

I have used pinned hinges on occasion but being old fashioned I still use cloth most of the time. I find them to be very flexible and durable.

BB

[Steve Helmick]

When I got my ex-Norm Whittle "Eagle", I noticed that it didn't have the hinges sealed (Robart Hinge Points). Flew it that way for awhile, thinking that Norm had not found it needed. Then, I discovered that there was a bit of tape adhesive left somewhere, and thought I'd better try sealing them. First, I got out a feeler gauge set and checked to see how much clearance there was... .018" maximum. But I sealed them anyway. I found it seemed to help the groove a little.

The surfaces don't move very much, and this last Spring when I asked Paul if he'd submit to flying it, he looked dubious about how little they travel. It does turn pretty well, 'tho it would do a lot better with 10 oz less baggage (67 oz on a reputed 638 sq. inches, IIRC).

IMO, if your flaps and elevators aren't removeable, you'll eventually wish they were.    Steve

[Frank Imbriaco]

 Recommend ULTRACOTE CLEAR. ONE ROLL =  3 lifetimes of airplane gap sealing per roll. R/C  and Ukie . Apply at 250- 275 degrees with socked iron and the results are excellent. (Just keep the iron away from ca hinges; something most Ukie guys don't use anyway) Removes easily  with a hairdryer( NOT  Mono-Kote heat gun) and any residue wipes clean with Prep- Sol type product. Apply to stab first, fully deflect elevator/flap, then seal . With large  R/C , cut, fold in half,  position with thin 6" machinist ruler, seal within the gap of the  t.e. of stab and l.e. of elev/ aileron.