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Author Topic: Molded Wing Tips  (Read 4187 times)

Offline Motorman

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Molded Wing Tips
« on: October 16, 2020, 06:54:14 PM »
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« Last Edit: August 19, 2021, 06:30:10 AM by Motorman »

Offline Dan McEntee

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Re: Molded Wing Tips
« Reply #1 on: October 16, 2020, 08:50:39 PM »
Twice. More work than was needed. Stuck with  hollowed blocks or flat tips. D>K

  Yeah, that would only be useful if you used the same tip shape on all your models or you made multiple different shaped molds that you could go back to.. Not a terrible idea but most people like a little variety.
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Offline Perry Rose

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Re: Molded Wing Tips
« Reply #2 on: October 17, 2020, 05:43:10 AM »
Bob Hunt molded some using balsa sheet.
I may be wrong but I doubt it.
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Offline Dan McEntee

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Re: Molded Wing Tips
« Reply #3 on: October 17, 2020, 11:53:08 AM »
  There have been R'C models with vacu-formed plastic wing tips, and I'm sure it's not new to control line models with all of the small kit manufacturers there have been over the years. If I were to do it, that is the way I would go, but then you may have some paint adhesion issues, or just try to dope on some tissue strips so you have a good base for paint.
   One way or another, you are going to have to carve at least one!!
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Offline Howard Rush

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Re: Molded Wing Tips
« Reply #4 on: October 17, 2020, 02:13:34 PM »
I wonder how light you could print one.  It would be cool to include the weight box and leadout guides in the prints.
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Offline FLOYD CARTER

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Re: Molded Wing Tips
« Reply #5 on: October 17, 2020, 02:29:35 PM »
I've discovered that some kits are using molded plastic or fiberglass parts.  They NEVER fit right, even with a lot of "fudging".  Then there is the impossible task of getting these parts to blend in to the rest of the balsa structure.  No thanks.
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Offline Mike Alimov

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Re: Molded Wing Tips
« Reply #6 on: October 17, 2020, 07:39:57 PM »

Mainly wondering how many layers of what kind of cloth would be ridged enough.

Motorman 8)

Two layers of 1.5 oz fiberglass on outside and one layer on the inside, with 2-2.5 mm blue construction foam in between, vacuum bagged overnight and then post- cured for 2 hours at 150 F.  Beats balsa in both weight and rigidity.
I agree with people who say this is too much work if you build a different airplane every time. 

Offline Dan McEntee

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Re: Molded Wing Tips
« Reply #7 on: October 18, 2020, 11:53:54 AM »
I wonder how light you could print one.  It would be cool to include the weight box and leadout guides in the prints.

    This is probably the best idea yet. You can design in the proper thickness where you need extra strength and help control the weight. you would need to and the surface smooth to remove the steps from the printing process anyway, so you could allow for that when sizing it to the end rib. I think this idea has some real merit to it.
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Offline Randy Powell

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Re: Molded Wing Tips
« Reply #8 on: October 19, 2020, 03:38:43 PM »
>> It would be cool to include the weight box and leadout guides in the prints.<<

Yea, get on that, Howard.
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Offline FLOYD CARTER

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Re: Molded Wing Tips
« Reply #9 on: October 25, 2020, 03:58:08 PM »
Some like to make an easy job harder.  Fiberglass molds mean carving a plug, mixing smelly, messy stuff.  Vacuum bagging?  Who has that equipment?  Solid carved balsa is wasteful, so I build-up balsa wingtips using an extra rib or 2 and planking with 1/16" sheet.  Resulting tip looks smooth without "starved horse" look, as in most Noblers.
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Offline Dave Hull

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Re: Molded Wing Tips
« Reply #10 on: October 28, 2020, 02:23:48 AM »
Moldy wing tips?

I just cleaned up a pair of plastic wingtips in a Stanzel Raider kit. Yep, they had some white powdery stuff collecting on them.* Well, the kit is probably 60-70 years old? Most of it came off with Windex. And all of it will come off with a bit of sandpaper when the time comes.

The engineering on these kits is really impressive. The plastic tips would appear to be injection molded using some type of clear plastic. The wood tip ribs have a rabbet that the tip slides right over. Near perfect fit. The hardwood nose and balsa fuse tapered splice has to be fondled to really be appreciated. Wonderful fits....

Anyone got a stuntmaster control unit?


Oops--I guess you guys wanted to talk about hand layed up molded wingtips, not moldy wingtips or injection molded tips.  My bad....

The Divot

*--Reminds me of all the government specs on plastics and associated environmental test requirements. Seems that a lot of plastics and potting materials were used in equipment that was deployed to Viet Nam. A lot of it acted as growth medium for mold. They learned from that experience.....

Online Ken Culbertson

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Re: Molded Wing Tips
« Reply #11 on: October 28, 2020, 01:56:07 PM »
Some like to make an easy job harder.  Fiberglass molds mean carving a plug, mixing smelly, messy stuff.  Vacuum bagging?  Who has that equipment?  Solid carved balsa is wasteful, so I build-up balsa wingtips using an extra rib or 2 and planking with 1/16" sheet.  Resulting tip looks smooth without "starved horse" look, as in most Noblers.
Same here.  Small block in the front, maybe 1" to round the front then planking for the rest.  Have to confess though that carving tips and top blocks was one of the pleasures in life that I miss.

I never build the same exact thing twice so I can't see making molds.  I do want to look into carving foam tips, covering them with fiberglass then hollowing out the foam and adding some balsa ribs to keep them from crushing.  Most of my tips are 4" swept that taper to about 1/2" thick where the leadouts exit.  Anything that would make them lighter.  I don't know, is glass heavier than planking?  While I am displaying my ignorance, is the blue foam everybody uses the insulation sheets you get at the box stores or something different.  One of ours has Pink.  Same thing?

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Offline Paul Wood

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Re: Molded Wing Tips
« Reply #12 on: October 28, 2020, 04:30:55 PM »
Same here.  Small block in the front, maybe 1" to round the front then planking for the rest.  Have to confess though that carving tips and top blocks was one of the pleasures in life that I miss.

I never build the same exact thing twice so I can't see making molds.  I do want to look into carving foam tips, covering them with fiberglass then hollowing out the foam and adding some balsa ribs to keep them from crushing.  Most of my tips are 4" swept that taper to about 1/2" thick where the leadouts exit.  Anything that would make them lighter.  I don't know, is glass heavier than planking?  While I am displaying my ignorance, is the blue foam everybody uses the insulation sheets you get at the box stores or something different.  One of ours has Pink.  Same thing?

Ken

My understanding is that pink and blue foam are the same, just different manufacturers. I use blue foam all the time for wing tips, fuselage top and bottom blocks. I glue the pieces together in the center of the piece with a very thin layer of epoxy. This allows me to carve the edges w/o getting into the glue. I coat the finished part with 3-4 layers of 3/4 oz fiberglass applied with Minnwax polycrylic (water based). Then I rub wood putty into the cloth grain using my fingers. Sand and seal with Minnwax. Then prime/paint. I have even been able to use a low heat shrink covering (Econokote, etc.) but you will have to coat first with epoxy to not allow much heat to reach the foam. The attached photos are planes that all have used this method. Works good for me, but I'm not a competitive flyer so an ounce or two of weight is not a problem. It is certainly an easy process to bench test to see if it works for you.

Paul

Offline Larry Renger

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Re: Molded Wing Tips
« Reply #13 on: November 13, 2020, 12:30:35 PM »
Carve a master tip out of basswood, epoxy finish it and then cast a silicone female mold. Use that spray expanding insulating foam to form your tips. Use as is or hollow out the inboard one to minimize needed tipweight and make lead out guide slot easier.

Should end up feather light and almost perfect surface finish.

Th RC guys have been doing parts this way for years.
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Online CircuitFlyer

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Re: Molded Wing Tips
« Reply #14 on: November 14, 2020, 11:19:26 AM »
My first attempt at 3D printed wing tips. Surface finish is poor but with some post finishing it could work. If you wanted to use it for a buck instead of carving it would be fine. Need another size or shape - just change the CAD model and print another. My little printer could fit a tip with a 10” chord in one go.

Paul
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Online CircuitFlyer

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Re: Molded Wing Tips
« Reply #15 on: November 14, 2020, 09:26:58 PM »
If the airfoil shape is in a CAD format, sure. These were made from a .dwg file. Sometimes a sketch profile can be drawn in CAD overtop of a .pdf of a plan with reasonable accuracy. From just a finished wing or rib, not so easy.

Paul
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Offline TDM

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Re: Molded Wing Tips
« Reply #16 on: November 15, 2020, 08:34:11 PM »
Make a female mold any way you want to. The layout is one layer outside is Style 1280 1.6 oz/sq yd Fiberglass Cloth and one layer of 200g 1X1M 3K Carbon Cloth Fabric Carbon Fiber on the inside.
The outside layer is for porosity and the inside layer for stiffness.
When you lay it out put some splurge epoxy Cabosil on the outer layer against the mold. Separately wet the glass carbon cloth bias at 45 degrees and dry with paper towels to remove excess epoxy and after that lay in the mold on top of the mold. This should be a light weight tip without to much excess epoxy flexible enough to be lightly pushed in to the finish place.
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Offline Steve Helmick

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Re: Molded Wing Tips
« Reply #17 on: December 29, 2020, 01:20:50 PM »
John Callentine (pardon if I spelled it wrong!) did an article on molding balsa wing tips in Stunt News, I think while it was still printed. It was something I'd pondered for awhile, but he actually did it. Somebody in AZ should know how he did it. I'd envisioned trying something more akin to building a cedar strip canoe.  :-\  Steve
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Offline Howard Rush

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Re: Molded Wing Tips
« Reply #18 on: December 29, 2020, 04:57:36 PM »
Cool. 

ABS sands and finishes nicely, so surface may not be a big deal. 
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Offline Alan Resinger

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Re: Molded Wing Tips
« Reply #19 on: December 30, 2020, 08:18:37 AM »
The tips on this wing panel weigh in at about 1.5g.  They are  .75oz glass cloth surface, 1.2mm Airex 70.55 foam sheet and .75oz glass on the iner surface, vacuum bagged in the mold.  Adjustable LE guide weighs 2.8g.  As we prime the mold prior to layup of the complete wing, the panel is ready for finish with just minor sandimg.


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