Preferred Elevator Hinge Method?
02-19-2023, 05:26 PM
#26
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Film hinges for the rudder should work just fine so long as the hinges are not supporting vertical shock loads from the tail wheel which would put shear stress on the hinges instead of the tensile loads for which they excel. Monokote and UntraCote bond to themselves really well. By covering the rudder leading edge and vertical stab trailing edge prior to applying the hinges, the hinges now have a better surface on which to adhere. The surface covering also helps lock the hinge straps in place. In addition, when applying the surface covering after the hinges are ironed in place, cut one piece of film covering large enough to cover one side of both the vertical stab and the rudder in one piece. Cover the vertical stab and then fully deflect the rudder and continue applying the film down into and back up out of the stab/rudder hinge valley and then continue covering the rest of the rudder. This does two things. It 1) totally seals the rudder hinge gap to increase aerodynamic effectiveness and 2) it helps ensure the rudder will stay attached even if the hinges were to fail. I do not do this for control line models because it will cause the control surface to try to deflect slightly and is a little stiffer, but for RC use with a strong servo, it won't be noticeable. To ease your mind, just install more hinges in a solid line of hinges instead of staggering them, i.e. XXXXXXXXXXXXXXXXX instead of XX XX XX XX XX. If you still have any doubts, just make a sample and then try to pull it apart. Bet you can't do it.
Thanks!
02-19-2023, 05:28 PM
#27
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Pull-Pull hinges
The hinge loads on a pull-pull system are not all that different than that of a single push rod system. When a pull-pull system is activated, there is a pull on essentially one side only, the same as when a single push rod system is pulled. The only difference is that the pull-pull system will have some forward pull on the rudder all the time. With film hinges, this thrust load (tension) is absorbed by the leading edge of the rudder pressing against the back of the vertical stab. For this, I recommend leaving the trailing edge of the vertical stabilizer somewhat flat and rounding the leading edge of the rudder so it has a surface on which to "roll" as the rudder is deflected.
02-22-2023, 06:02 PM
#28
So I get a little lost in your explanation of the hinge straps. Are those straps once sealed/adhered together (one up, one down, 1/4" overlap) a 1/2" wide by 3 3/4" long? Once applied it would go past the initial leading and trailing edge pieces that were applied. Is that right? Then I should cover the elevator and stab right up to the hinge line capturing the hinge strap. If so, I think I got it. Thanks.
Last edited by Tom Nied; 02-22-2023 at 06:05 PM.
02-22-2023, 07:35 PM
#29
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Hinge straps
Hi Tom, Yes you have it right. The main reason for covering the leading and trailing edges prior to attaching the hinges is because once the hinges are finished, the leading and trailing edges are no longer accessible to be covered. Not a problem with dope but it is with film. The top layer of film will also help anchor the hinge straps in place. If the hinge were to be highly stressed, then yes, covering more of the leading and trailing edges would provide for a more secure hinge strap attachment because the UltraCote sticks better to itself than it does to raw balsa wood. Also the hinges can be cut wider than 1/2" if desired for extra strength. Attached are some photos of the flap assembly for a Sig Twister I am building. Since the flap has to slide through the wing hole before inserting the wing, it is not possible to hinge the flap to the wing prior to installing the wing. The hinge straps will be ironed onto the wing after the wing is glued to the fuselage. As you can see, it was possible to entirely cover the flap after ironing the hinge straps onto the flap.
Assuming you are going to cover your .35 Buster with UltraCote or Monokote, then film hinges would be perfect for hinging the thin elevator to the stabilizer... no holes, no slots. Hope this helps. Let me know if you have any questions.
David
Leading edge of flap was covered prior to installing hinge straps. then the entire flap was covered.
Flap hinge is almost invisible once the top layer of film is applied over the hinge straps.
hinges ready to be ironed on after wing is glued to fuselage
Wing trailing edge covered prior to hinging. Flap has hinge straps installed and then covered to seal in the hinge straps.
Assuming you are going to cover your .35 Buster with UltraCote or Monokote, then film hinges would be perfect for hinging the thin elevator to the stabilizer... no holes, no slots. Hope this helps. Let me know if you have any questions.
David
Leading edge of flap was covered prior to installing hinge straps. then the entire flap was covered.
Flap hinge is almost invisible once the top layer of film is applied over the hinge straps.
hinges ready to be ironed on after wing is glued to fuselage
Wing trailing edge covered prior to hinging. Flap has hinge straps installed and then covered to seal in the hinge straps.
Last edited by LLRCFlyer; 02-22-2023 at 07:41 PM. Reason: typos
02-22-2023, 08:04 PM
#30
This makes so much sense that I'm daffy with excitement. My Brodak Buster has been sitting on a table in the basement unfinished because I got stuck on how I was going to do the hinges. I think properly installed MonoKote hinges like you describe is a really neat procedure. I've known about MonoKote hinges but never thought that they would hold up to the rigors of a Controline model. I will do as you suggest and just take some scrap balsa and test it. Thanks for sharing that man. Tom.
08-01-2023, 06:32 AM
#31
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Tom,
Here are some photos of the finished Twister. As you can see, the hinges are nearly invisible. It flies fine and the hinges are still perfect. It balanced perfectly with an OS Max .35S without any balancing weights. How is your Buster coming along?
David
Here are some photos of the finished Twister. As you can see, the hinges are nearly invisible. It flies fine and the hinges are still perfect. It balanced perfectly with an OS Max .35S without any balancing weights. How is your Buster coming along?
David
08-01-2023, 08:56 AM
#33
Dave, that's a beautiful looking Twister. I don't see it in your photos but you may want to add a fairlead (some have even just used a cotter pin) to prevent the pushrod from the flap to the elevator from bending when its pushing. But that is a very good looking Twister. Did you MonoKote the fuselage as well? My Buster project got shelved once again. The GF and I moved 1700 miles from Carol Stream Illinois to Queen Creek Arizona. So I had to pack all my models, built, half built, kit or ARF. I'm pretty sure it made it, I should unpack the wing and see how it did. Moving is the worst thing for a modeler. Imagine deciding which planes go and which planes get junked or given away. Also the work shop has to be disassembled. But I really like your MonoKote hinges and when I can get back to it I will certainly use your suggestion. Keep those lines tight. Tom.
08-01-2023, 10:07 AM
#34
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Tom,
The Twister is covered in orange and white UltraCote, including the fuselage. I did apply some Cover Grip (by Deluxe) to the forward fuselage plywood doublers, wing tips, and to the wing/fuselage joints to help ensure the Ultra Cote will not loosen in these areas. I thought about adding a fairlead. However, I built it completely stock (except for the landing gear) and did not lengthen the fuselage like a Francherized Twister. The supplied elevator push rod is quite stiff and is so thick that I had to seriously drill out the control horn holes to get it to fit. So far, it has not shown any signs of flexing, even in the tightest loops.
I hope you enjoy the Arizona weather. Definitely better for winter flying. Post some photos of your Buster when you get it finished. I remember when I had to move, I ended up giving away several airplanes and some nice kits rather than move them and have to pay storage costs. I wish now that I would have been able to keep several of them ... R/C Nobler, CG 1/2A Skylane, CG Ranger 42, CG .35 Cosmic Wind, Sig Super Chipmunk, Astron .40 (Bill Evans) etc. oh well...
David
The Twister is covered in orange and white UltraCote, including the fuselage. I did apply some Cover Grip (by Deluxe) to the forward fuselage plywood doublers, wing tips, and to the wing/fuselage joints to help ensure the Ultra Cote will not loosen in these areas. I thought about adding a fairlead. However, I built it completely stock (except for the landing gear) and did not lengthen the fuselage like a Francherized Twister. The supplied elevator push rod is quite stiff and is so thick that I had to seriously drill out the control horn holes to get it to fit. So far, it has not shown any signs of flexing, even in the tightest loops.
I hope you enjoy the Arizona weather. Definitely better for winter flying. Post some photos of your Buster when you get it finished. I remember when I had to move, I ended up giving away several airplanes and some nice kits rather than move them and have to pay storage costs. I wish now that I would have been able to keep several of them ... R/C Nobler, CG 1/2A Skylane, CG Ranger 42, CG .35 Cosmic Wind, Sig Super Chipmunk, Astron .40 (Bill Evans) etc. oh well...
David
10-14-2023, 09:52 AM
#35
Senior Member
I’ve got a problem way too many kits and they will never get built. Hindge,! I use Aircraft grade A Fabric and Stits polyfibre D-103 still have some Ambroade glue the hot summers here keep the cloth hindge tight and they don’t deteriorate.
10-15-2023, 03:36 PM
#36
Senior Member
Hindges
I do old school and it's cheaper than buying the newer style. I've got some grade A fabric tapes that you use to cover to cover wing rib stitching. Pinked edge and I cut a two inch tape twice gives me about a3/4,inch wide hindge. Its been years sense Ive seen fabric hindges in a hobby shop. I use to fly RC and used the fabric method never had an issue.AJ
10-15-2023, 04:01 PM
#37
Don't they get fuel saturated or brittle? I used cloth hinges on my first 1/2'As back in the '60. But those planes didn't last long. The hinge material supplied in Carl Goldberg kits I believe was nylon..
Last edited by Tom Nied; 10-15-2023 at 04:02 PM. Reason: grammar
10-15-2023, 05:25 PM
#38
Senior Member
Hinges
Well I don't know the fuel I use has lots of caster. And when I finish I use Silver xcide mixed with Butirate dope. Never had one fail. A few Of my planes are 45 years old. My most recient build is the Brodak Bi Slob. I used the same material its old Aircraft cotton with pinked edges I coat the balsa with 3 coats of nitrate. To fill the balsa for a smoth finish I mix talc with BUTIRATE dope. Then finish in silver. I tried using stits polyfibre finish but I went back to randolph. They supply to Sig And Brodak. Those just 9 dollar bottles. If I used color I would buy a Quart. Did buy a quart of yellow. For my wings. Just use the silver I know I am going to crash so why do a nice finish. Also much easier to repair. My planes are not pretty but I sure enjoy getting dizzy. AJ.
