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May 18, 2019, 09:39 PM
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Thread OP
The outer wing joiner rods, webs & locater pins are now fit in the cores. The rear locater pins are 1/4" x 8" CF solid rods which are a no-slop fit into the 9/32 x .014 aluminum tubes. The photo also shows the plugged wooden anchor ends that were also reinforced with 4oz. FG cloth to make a solid stop for the pins. The pins & anchors needed to be parallel and level with the joiner so the wings will slide together. Hopefully the stiff pins, along with the main joiner rods will strengthen the joint and transfer the twisting forces to the inner wing, where they will be nullified. The yellow tape marks the aileron. This is all uncharted territory for me, so feel free to comment on any red flags, alternate methods or ask questions. . Since I changed the camber from 3.5 to 3.0 after I had the fuse finished, the fuse wing root needs a little modification and filling to match the less-draggy 3.0 airfoil of the wing root. (thanks John and Kenneth). Also, the webs still need to be covered with the CF tube, the servo wire channels need to be cut and the ply outer wing ribs need to be fit.
Last edited by flyingfever; May 18, 2019 at 09:48 PM.
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Jun 11, 2019, 06:17 PM
Everything's A Composite
Knoll53's Avatar
Along the lines of encouragement, here is some real world proof of the strength of yyz spar method. I had a chance to test one of his wing panels in bending. If you study the lever arm and loads used (me at 180 lbs.) you can see that it would be unlikely that this wing would ever fail from any aero loads.

EB-29 Spar Testing to failure (0 min 48 sec)
Jun 11, 2019, 06:43 PM
"Fly"Fisherman
Asher Carmichael's Avatar
Wow! That’s really compress... er impressive. Not surprised in the least, however. “Mikes the man.”
Jun 27, 2019, 10:56 PM
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Thread OP
Thanks for posting the wing test video. Without the video, it's unbelievable. I wonder what the spar, web, caps & skins configurations are,? After several weeks of many chores, I'm finally ready to laminate the spar webs with the braided 6oz. bias CF tube, I wonder if one lamination is sufficient, or should I double the tube, maybe out to about 1/3rd ? It's an 8-foot inner wing panel.
Any ideas or suggestions? No photos yet---sorry. Thanks.
Last edited by flyingfever; Jun 27, 2019 at 11:13 PM.
Jun 28, 2019, 12:32 AM
Everything's A Composite
Knoll53's Avatar
you can check yyz EB-29 build log for all the details on this wing construction. it was a rather thin wing and the spar construction was maxed out. He didn't miss a trick. The only thing he could have done to make it stronger would be to make the spar wider.

IMHO the most common failure is the connection from the spar caps to the joiner. If it is not wrapped, the joiner will just pry the spar caps apart. Having a strong sleeve around the joiner will not help this prying force. The spar caps must be wrapped.

With a very long joiner you can reduce this prying force such that wrapping would not be needed. In this case the joiner is more of a spar replacement. On the other hand, with proper wrapping, a very short joiner is possible.
Jun 28, 2019, 02:14 AM
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Kenneth Paine's Avatar
Bob,

The thread that Knoll53 mentions is here https://www.rcgroups.com/forums/show...d#post13687310

It is a masterclass in spar building.


Kenneth
Apr 04, 2020, 09:03 PM
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Surprise---Back at it again.


Finally got a few things done, The root and outer wing ribs needed to be laminated, each with one 6oz. & one 2oz. layers of CF, with peel-ply. The cloth was held in position with a light mist of spray adhesive before wetting out. Also have the final fit of the root ribs, now 3.0 camber to the fuse which was 3.5 and the 9-pin connectors were fit with the 3* angle. The locater & mounting bolts are also fit to the fuse and wings (probably overkill).. I will be able to make more progress soon. Many thanks to all who have helped to get to this point, and to all who have followed.. Yes---- I will finish this plane.
Last edited by flyingfever; Apr 04, 2020 at 10:02 PM.
Apr 08, 2020, 02:45 PM
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Nietzsche's Avatar
Amazing!

this has to be the longest project on rcgroups.com. Seems like there should be an award for this thread or something...

Can't wait to read more.

Nietzsche
Apr 14, 2020, 01:49 PM
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Well, Nietz, if there ever is such an award, it'll go to WooWho. He started 4 mo. (sept. '14) before me, his Diana is light years ahead of mine, and his workmanship & detail are top notch. The 9-pin connecters and wires are soldered. Next is to CF the spar webs.
Last edited by flyingfever; Apr 14, 2020 at 02:03 PM.
Apr 18, 2020, 05:29 PM
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I was concerned with the resulting strength of the outer wing when the servo pockets were cut out at core 6. It wouldn't leave much wing surface, and there will be a wingtip wheel at core 7, so I lengthened the spar & web. The servo locations and pockets are located so the servo control horns are centered on a core line, which hopefully will help in 90* control horn placement after the surfaces have been cut loose and everything is black. Also, I got the fuse root servo connector holes done. It was a real challenge cutting though the 4 layers of ply and 6 CF with drills, files, cutoff wheels, a drum sander and a router to match up with the wing root rib connectors at the same angles. They still need a little smoothing, but do line up. There will eventually be hardwood mounting blocks epoxied from the inside in place at both sides of the holes which will provide mounting surface at the correct depth to screw the connectors in place and leave the center open for the wires to exit to the RX. Now I'm finally ready to CF the main webs.
Last edited by flyingfever; Apr 18, 2020 at 07:45 PM.
Apr 25, 2020, 08:05 PM
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I decided to figure out and cut the 50k CF tows for the 4 spar caps. Each is 20 or 21 tows (I lost track) at the roots, tapering, to 1 at the tips. After much consideration, I have pretty much given up hope for any scale wing flex. The spool of CF was put at the root ends, so each length x 4 , starting with the longest at the tip, was cut in place, then pulled out to the next position, etc., so cutting the 80 pieces wasn't too difficult.. Also the core spaces above the webs will have to be enlarged a bit in some places to allow all the tow to press in and around the webs. I'll set these aside for now. I also have the spar webs CF'd with the woven tubing and permanently attached to the boxes, but I will have to wait to post for at least a week for a replacement camera battery to arrive. Meanwhile, the servo wires need to be cut to length, the connectors attached and the harnesses assembled. I intend to hook up all servos in place to test with my rx & tx before burying them at their respective servo pocket locations. The sheet of 2" foam is for lengthening my hotbox for the wing bagging. Questions, suggestions, red flags & comments welcome. Thanks.
Last edited by flyingfever; Apr 26, 2020 at 12:06 PM.
Apr 26, 2020, 07:14 AM
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Spar - Calculation for the Structure (Carbon Layers)


Amazing and subscribed!! Congratulations for the progress done!!

By the way, is there any Excel file or any program to calculate the Carbon Fiber layers for the fuselage / wings, and also to calculate the Spar for the Wings? I'm in the process of designing a new glider in 1:3rd scale, estimated weight of 14-16 kg and would like to know how to calculate the layers for it, so it can support a minimum of 20G's

Many thanks,
Best regards



Quote:
Originally Posted by flyingfever
I decided to figure out and cut the 50k CF tows for the 4 spar caps. Each is 20 or 21 tows (I lost track) at the roots, tapering, to 1 at the tips. After much consideration, I have pretty much given up hope for any scale wing flex. The spool of CF was put at the root ends, so each length x 4 , starting with the longest at the tip, was cut in place, then pulled out to the next position, etc., so cutting the 80 pieces wasn't too difficult.. Also the core spaces above the webs will have to be enlarged a bit in some places to allow all the tow to press in and around the webs. I'll set these aside for now. I also have the spar webs CF'd with the woven tubing and permanently attached to the boxes, but I will have to wait to post for at least a week for a replacement camera battery to arrive. Meanwhile, the servo wires need to be cut to length, the connectors attached and the harnesses assembled. I intend to hook up all servos in place to test with my rx & tx before burying them at their respective servo pocket locations. The sheet of 2" foam is for lengthening my hotbox for the wing bagging. Questions, suggestions & comments welcome. Thanks.
Apr 26, 2020, 09:21 AM
yyz
yyz
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yyz's Avatar
You're rounding 3rd, Bob. Keep up the great work.
Apr 26, 2020, 09:19 PM
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Thread OP
Gmoreno, Thanks for following my build and your comments. I don't have any experience or knowledge of the Excel programs or any other programs, tho some must exist. If you go back to #148, a builder has a 9m Nimbus hollow core that he built, and he took the measurements and weight of mine and calculated the connecting rod for mine @ 10g. His calculations was for Carbon, glass, and steel, I think. For the fuse layers, spars and caps and wing laminations, I studied every build of this size and up that I could find on RCG, and noted how they built theirs. Most of the builds used mostly glass laminations for the skins with CF reinforcements at stress sites, and proved to be plenty strong. Just to make sure of the strength I chose my fuse layers to be all CF and Kevlar, with a bit of glass, then added another layer or more inside with extra reinforcements for good measure. Then, I ask for advice here, and usually get some answers. The number and size of spar cap tows was mainly taken from a chart of spar and CF tow cap sizes developed and shared by mikegbough. He has built 20 or more of these big birds, with a 10m one as his last one. He developed a system that works as a result of trial and error--seldom error. I chose his suggested numbers and added more ---hopefully it'll be enough. I wish I could help you, but hopefully some of the guys following here can respond to your questions. They are more than welcome to answer here, and have my invitation to do so. I hope some will respond here. what model are you designing, and what kind of flying do you do to need a 20g+ plane?
Last edited by flyingfever; Apr 26, 2020 at 10:24 PM.
Apr 26, 2020, 09:22 PM
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Quote:
Originally Posted by yyz
You're rounding 3rd, Bob. Keep up the great work.
Thankyou, Mike, I truly .needed that. However, I feel more like I'm sliding into 3rd.


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