Mcclain Wing Cores 24" virgin foam/EPP wing - RC Groups
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Apr 07, 2008, 07:32 PM
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Mcclain Wing Cores 24" virgin foam/EPP wing

Hey folks

Have been perusing the treads for months regarding the McClain Foam Wing Cores addition of flying wings to their catalog of foam cores and plans.

After a few calls with questions to Jeff at McClain Foam Cores, I offered to do a building thread based on one of his 24" wings as I had time and tools.

Jeff agreed to send me the 24" for a building thread to get an idea of how he makes his stuff / quality/ cutting, materials and design as I had never seen these wings before nor knew who designed them.

Jeff has been making cores for scale and combat planes based on the Gus Morifs plans as well as for power slope and slope soaring for quite a while. Several years ago a close friend built a mosquito from his 1/12 cores and plans with excellent results. I have read several threads based on his combat cores - so the guy has a good track record as well as phenomenal Ebay feedback.

This wing can be bought on Jeff's Ebay store:

I will call the build as I see it, this is a chance to see the design to make sure it works as advertised.

I am making some assumptions in this thread:

1) you have limited experience with building your own airplane but have build at least an ARF.
2) you have basic tool knowledge like how and when to use an exacto blade over an exacto saw.
3) you have a rudimentary knowledge of how your radio gear works and the proper tools for installation.

Other than this type stuff, I am taking it pretty simple and pretty straight forward in the build.

Please don't rail on me for being oversimplified for those that do know the basics . . .there are many that do not! There are many that would not even dream of picking up a kit type design which severely limits the options in performance and fun planes available.

In the old days you had to build your airplane to fly it . . now we have folks in China doing that part for us so that we can enjoy the flying side, fortunately, I enjoy both sides of the hobby.

Last edited by pval3; May 31, 2008 at 04:39 PM. Reason: video link!
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Apr 07, 2008, 07:32 PM
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Here are the specs on the 24" MWC wing.

24 Inch wing span

Wing area is 108

CG is 3-7/16 to 3-11/16 from the center L.E.

The L.E. is 1/2 inch EPP Foam

The main body of the wing is virgin white bead foam.
Apr 07, 2008, 07:37 PM
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new arrival

Here is the way it comes in from McClain Wing Cores. The box was solid and there was no damage to the box or wing cores.

Packing was phenomenal; cores were centered in the box with shredded paper. Jeff packed two sets of cores in the box.
Apr 07, 2008, 07:41 PM
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contents of the box

contents of the box

Here are the contents of the box. The main part of the wing is virgin foam. The leading edges are EPP. Cores were taped in the beds and secured with shipping tape. The EPP was kept together with masking tape.
My overall impression of the materials at this point is that the foam and EPP is clean, no ripples, no pulls and no inconsistencies in the foil along the span. Very impressive cutting.

I am doing concurrent builds on the wings that Mcclain offers.

The 36" wing thread is located here:
Apr 07, 2008, 07:50 PM
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here are pics of the root and tip of the cores

here are pics of the root and tip of the cores
Apr 07, 2008, 08:06 PM
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EPP leading edge and weights

EPP leading edge

The EPP leading edges were cut with the appropriate sweep angle cut for you.
They were also marked clearly for those that might not be familiar with airfoil shape and how to figure the right from the left halves on the leading edge material.

The weight of the cores and leading edges themselves are a scant .4 oz!
Attached Thumbnails
Apr 07, 2008, 08:11 PM
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out of the beds - and some foam core wing basics!

Here are the cores out of the beds with the leading edges placed in front of them.

OK, this is where we get into some basics…
For those that have never made the mistake – your too good – or someone gave you this tip before you started building your first foam wing . . . keep your chides to yourself!
Over the years I have seen so many new folks show up to the field with wings that are assembled upside down or backwards that it is not even close to funny.
To prevent this:
Mark the top of the airfoil with a” T” and with the side of the wing that you are holding – i.e. L or R…
Mark your leading edges with L or R also BEFORE you start working on your wing. Make sure you also place the same type of marking on your core beds!
Many are also compelled to “get rid of” the trash from the extra materials from the cores . . .”all I need is my wing” – NO – you need those core beds throughout the assembly process. These protect your cores from damage from loose items on your building board as well as to align the cores for joining and stability up until you finish covering the model – DON’T THROW THE EXTRA FOAM AWAY!
Apr 09, 2008, 10:03 PM
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cores and le

Here are the cores out of the beds with the leading edges placed in front of them.
Apr 23, 2008, 11:13 PM
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pieces n parts

Here is how to “set up “your building table/area . . Place the thin core bed tops and bottoms flat on your board and then place the cores into them so they lay flat.

The center section of this core bed is the top of the airfoil, do not throw this away as it makes a great hold down while letting the glue set when you join the wing.

Pay no mind to all the assorted junk on the peg board, this is my secondary building area and I use the desk for house projects and hobby projects!
Apr 23, 2008, 11:18 PM
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Building materials:
I have been building with foam for a long time, from cutting and skinning my own cores in the 80s to the park fliers of today . There are more glues and methods of using them than I can count. I have found that for my own sanity, there are a few that have consistently worked well for me with these wings.
The primary glue I use is UHU foam. It is available from both Michaels and AC Moore Craft Stores. Best part of all is that every Sunday there is a coupon in the news paper for 40% off one item. This makes a 4 buck tube of glue cost a measly 2 bucks! I have included a picture of the packaging as there are about 10 different glues made by UHU – many are not foam compatible. This glue is used like a contact cement and remains flexible over time so if you hit ole terra firma, the EPP and the glue give to absorb the impact. With CA type glues and epoxy, over time they become brittle and will crack when you hit the ground or stress the airframe.
The other glue I use heavily is gorilla glue. This has similar properties as the UHU but has a foaming action that is perfect to fill gaps in seams and remains flexible over time but is not as flexible as the UHU. It will bond almost anything to anything whereas the UHU will only bond foams.
Both of these glues are not effected my temperature variations as epoxy is, since I moved into my new home, my building area is in the garage – temperature variation is a fact of life and the consistency I have found with these glues is great.

NOTE: spray 77 craft glue works fine with the white foam and the EPP but 3M spray 90 DOES NOT...for those of you that have done a Ritewing build or seen one, this is the fantastic glue that allows you to use spray glue in place of epoxy for glassing. It works great on the EPP but will melt the white foam faster than you can come to the realization that part of your model just melted into the air!

Use the Spray 77 only for providing extra tack for the fiber tape toward the end of the build!
Apr 23, 2008, 11:19 PM
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starting out -

Lay the Right Core bed bottom on the table flat.

Match the Right wing and Right EPP leading edge over the core

Place a sheet of wax paper over the core bed between the wing and the core bed. This prevents the glue from sticking to the core.

Pick up the wing core and apply a bead of UHU glue on the face of the leading edge of the foam core in a tooth shape pattern.

DO not use too much glue as it will increase the drying time.
Use a finger to spread the glue thinly and evenly all along the seam.
Apr 23, 2008, 11:21 PM
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leading edge

Once it is spread evenly and consistently, place to the core on top of the wax paper in the core bed, slide the core back ¼” from the front of the core bed.
Apply a bead of UHU glue to the back of the EPP leading edge in the same manner listed above.
Apr 23, 2008, 11:23 PM
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When you are finished spreading the glue, place the EPP leading edge in front of the core.

Make sure the EPP leading edge is flat on the core bed.

Put a ruler against the center of the wing and butt it up tight against the foam.

Starting with the root, press the EPP against the foam making sure that it is both flat against the bed and the ruler and gently work out to the tip of the wing half
Gently – adjust for any areas that are not contacting. You have about 2 minutes before the glue really starts to bite so work quickly but accurately
Apr 23, 2008, 11:24 PM
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sitting time

Use the top of the core bed to apply pressure to the top and bottom of the joint and keep it together. Allow the core bed to extend about 3/8” ahead of the core over the epp.

The wax paper will prevent the core beds from sticking.

Allow to sit for about 20 minutes for a good bond.
Apr 23, 2008, 11:25 PM
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other side

Move to the other half.

Same procedure as before but place the wing halves together to ensure that the leading edges will tightly fit.


I like to place a straight edge between the cores to act as a good solid surface while pressing the other side together.

Once I am sure it is initially holding together, take the core and check it to make sure it fits together with the other half without any gaps. You have a few seconds to make small adjustments if it is not.

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