Q-500 Racing Discuss AMA 428, AMA 424, and any other variants of Quickie 500 racing

Q500 wing with no SPAR ??

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Old 04-08-2019, 06:10 PM
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TampaRC
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Default Q500 wing with no SPAR ??

I am building my first q500 and its a sheeted foam core wing that has no spar what soever. The wing panels are simply butt jointed with "5 min epoxy". The center section is to be glassed, but how is that enough to hold the wing together at 100mph + ?
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Old 04-09-2019, 01:43 PM
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Depends in part on the weight of the glass used. A chunk of 6 ounce would prevent things from coming apart quite well.

There are many models out there with sparless foam wings. In your case the sheeting takes on much of the job of the spar. Another trick is to run a strip of fiberglass re-enforced packing tape down the length of the bottom of the wing where a spar would normally be. One continuous run tip to tip then sheet the bottom.

And I'd use 30 min epoxy for the joint and the glass.
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Old 04-09-2019, 11:39 PM
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That's exactly the way we used to build them back in the day. Even when powered with Rossi .40 and Webra speed .40 engines. If you were going to be running any more power then that I would do an 8" long wing joiner. When glassing it is best to use several layers of fairly light cloth. I always used 3oz and started with a 8" peice followed by a 6" peice and lastly a 4" peice. Use a good laminating resin such a Z poxy finishing resin which is really just a laminating resin.
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Old 04-14-2019, 07:13 AM
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Originally Posted by TampaRC View Post
I am building my first q500 and its a sheeted foam core wing that has no spar what soever. The wing panels are simply butt jointed with "5 min epoxy". The center section is to be glassed, but how is that enough to hold the wing together at 100mph + ?
I put a vertical sheer of carbon on mine and the wings are good for the fastest classes.

Sheet a Q500 Wing
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Old 04-20-2019, 09:10 AM
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Just including this reply for those searching similar glassing tasks in the future:

As I have learned from a mentor, fiber orientation can help in some instances too.

Bi-directional cloth applied to the center section with fibers running 0-90 will have only those running span-wise providing strength across the butt-joint. Those fibers running chord-wise - which comprise half the material - are not providing strength across the joint. [++++++l++++++]
You may achieve better results with uni-directional material where all the fibers are running 90 degrees to the joint. [--------l--------]

If you have enough bi-directional material to do the job and the cloth is applied on the bias (45/45), then all the fibers will be working to strengthen the joint like the uni- but with the added benefit of torsional rigidity. [XXXXXXlXXXXXX]

Last edited by H5606; 04-20-2019 at 09:17 AM.
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Old 04-22-2019, 08:04 AM
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Some pretty good info in that last post. A couple things I would like to add. The practice of running fiber orientation is a good one however you need to know what your reference point is. The fiber orientation on a plain weave fabric runs in two directions the " Warp " fiber runs the length of the roll and the " fill " fiber runs at 90 degrees to the roll. When fiber orientation is specified it is in relationship to the warp. When talking about unidirectional fabrics, they are usually only available in Carbon Fiber.
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Old 04-27-2019, 05:11 PM
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Originally Posted by speedracerntrixie View Post
The practice of running fiber orientation is a good one however you need to know what your reference point is. The fiber orientation on a plain weave fabric runs in two directions the " Warp " fiber runs the length of the roll and the " fill " fiber runs at 90 degrees to the roll. When fiber orientation is specified it is in relationship to the warp.


From personal experience, I was reprimanded for taking too long to cut some cloth for a project. Boss sez: "What took you so long? - I was getting ready to send out a search party." Me: "Oh, I was cleaning up the area after cutting materials, putting some things away, and then I was talking with someone in the hallway." Boss: "Geez, I didn't ask you to weave cloth, did I? We don't have all day! This task should have taken minutes, not hours! Please don't tell me you're cutting one piece of cloth at a time." Fact of the matter is, I spent an enormous amount of time deliberating how to keep fiber orientation while cutting cloth off the roll. After much head scratching, I had to draw some arrows on both sides of the pattern and turn it over several times to help me see what happens here.

1) Stacking two pieces of plain weave cloth while using care to maintain orientation coming off the roll and cutting both with a pattern at the same time gives identical pieces - two rights or two lefts and both pieces will have warp and fill fibers running exactly alike. For this example, slashes can represent the fibers running the length of the roll. [//>] [//>] 2) Using care to turn only one of the pieces over now gives a left and a right with fiber orientation in a mirrored or balanced manner. [//>] [<\\] 3) Overlapping a portion of the two pieces gives two layers in the center and one layer outboard. [<\X/>]

Also from experience, early AMA 428 class Q-500s were shown to be having wing failures in compression, not tension - so strength was commonly achieved by concentrating on reinforcement to the top of the wing, not the bottom. Glass coverage on the top of the wing usually extended out further than the bottom to avoid stress concentration - especially at the LE. In other words, not simply a single wrap of narrow, constant-width cloth around the wing panel joint which may have been fine for 424.

Last edited by H5606; 04-27-2019 at 05:52 PM.
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Old 04-27-2019, 07:10 PM
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Great post! Most wing failures I have seen did not happen at dead center but usually just outside the fuselage. For that reason I always apply the cloth to extend at least one fuselage width past the fuselage. My last two designs have rather thin wings so a vertical wing joiner of Divinicell with 3.6oz bagged front and back. The joiner is flush to the exterior of the wing skins so that when the center section is glassed the glass has a connection to the joiner. Very light and strong.
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