|Apr 04, 2008, 02:16 PM|
Mcclain Wing Cores 36" virgin foam/EPP wing
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 36" wings as I had time and tools.
Jeff agreed to send me the 36" 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:
Since I started the building process and from feedback on the site, he is now also offering an all EPP version of the same wing:
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.
So here goes!
UPDATE - first video...
PS. I am doing concurrent builds of the 24" and 36" wings. To prevent confusion, I have moved that thread here:
VIDEO LINK: http://www.rcgroups.com/forums/showthread.php?t=872684
|Apr 04, 2008, 04:43 PM|
here it is out of the box
Box had the 36" cores in two parts:
front leading edges cleanly cut from epp with the R and L leading edges clearly marked.
rear virgin foam very nicely cut from white expanded bead foam with medium density foam.
This sale was only for the cores and that was what was in the box.
The rest is up to the builder in so far as spars, hardware, and wood for the elevons and cloroplast for the winglets / tips.
The cores can be used for slope flying or Electric powered conversion so the world is your oyster! Why include stuff you going to throw away. The price reflects that too, these are very reasonably priced cores.
|Apr 04, 2008, 05:05 PM|
36 Inch wing span
Wing area is 162 sq.in.
CG is 5-3/16 to 5-9/16 from the center L.E.
The L.E. is 2 inch EPP Foam
The main body of the wing is virgin white bead foam.
the cores weighed in at 1.1 oz.
|Apr 04, 2008, 06:34 PM|
I know there are more opinions on glues than there is space to post . . so this is what I am using on -most - of my foam based planes.
UHU styro glue.
This stuff sticks any foam to any foam without issue. It is flexible to a point and works like a contact cement so you have a few seconds of play to move the pieces into place if you muck it up and it is not effected by temperature. It sticks regardless even in an impact as it has some flex . . . . bounces with the EPP! Best part of all, this glue is available from Michael's Crafts or AC Moore which both run weekly coupons in the sunday paper for 40%- 50% off one regularly priced product! a 5.00 tube of glue becomes a 2.50 tube of glue
I stopped using epoxy as it is more susceptible to temperature than gorilla glue and does not have the foaming options that gorilla glue has. Since my building area has been pushed out into the garage since I moved into my new home a few years ago - this is a consideration as the temperature in my work space varies from low teens to high 90's.
|Apr 04, 2008, 07:02 PM|
|Apr 04, 2008, 07:25 PM|
radio and power options
Well, this one is way up there for discussion!
One of the main considerations with this wing is - what do you want to do with it. Are you looking for speed or are you looking for something that is more aimed at fun/sport flying.
Fortunately you can run a fast motor slower than full throttle but you cant run a slow motor faster!
With the bevy of options out there, there are limitless options. After looking at the planform and airfoil, I think you will be able to achieve a pretty wide speed envelope based on the wingloading.
It is my opinion that this would fit a niche somewhere between a Hobby People Wild Wing and the 36" "rite" wing. the stability at extreme speeds will be diminished because the tips are thin and narrow and probably prone to vibration unless glassed the rite style, however, I do not think that the makeup of the wing with both epp and expanded bead will hold up anything like a rite wing in an 75+ mph hit.
It would be my opinion that a speed range could be considered between mild range for 25 and 45mph with a basic 24mm cdrom type motor or tower pro motor on 2-3s and light build or 25-75 on a slightly more robust build with carbon spars and a higher KV outrunner like a dons wicked Jr., an AXI 2208 series or one of the lighter options from Justgofly.com.
For esc's - what ever you like is fine. You are looking for something 10-25 amps with a basic set up or 18-30 amp range with a hotter set up
If brushless is not your thing, I would highly recommend a johnston 250 motor for the sport crowd or a good ole graupner speed 400 6v from hobby lobby. There are a bunch of new Chinese brushed speed controllers out that are compatible with the lipo batteries, a 2s 1000 mah 20c for the johnston or a 1500 2s 20c pack for the speed 400 set up. Either will yield great performance .
There are two considerations for the servos with the understanding that sub micros are needed to keep overall weight down-
how fast do you want to go with the plane?
do you want to risk having to tear the servos out to replace stripped gears?
For the budget minded with the lighter set ups and 2s sport motors, the hecktronic 6 gram light weight servos from hobbycity.com work fine.
For the slightly faster and heavier setups, you need the 9 gram servos to fit the bill. At 3 bucks a piece, you cant go wrong . . do pick up at least one set of extra gears when you buy them as anyone who flies wings will tell you - if you haven't stripped gears yet - - you will soon!
For the folks that want a faster set up or better quality gearing, I go one of two ways.
I really like the gws pico servos. These are a little heavier than some of the servos out there but the gears are the toughest I have found in a budget servo. The torque is great and the quality has been consistent ever since I started using them when they first came to market 8 years ago.
For things I care about or things that are going to fast not to care about there is only one option - jr servos. I have them in anything that I am going to push hard. For the speed freaks, they have metal gear sub micros and for the budget minded they have their basic ultralight weight servos. All of them are about the same in weight, but the JR gears and resolution for precision is unmatched.
Hitech HS55's are fine too.
If you plan to use this sloping soaring, a higher torque sub micro servo is more inline for you as a little extra wingloading wouldn't hurt you and the extra meat in the gear train will help significantly when contacting terra firma!
For mine I have opted for the following:
Don's Wicked Jr motor
3S 20c Kokam 1500 pack
25 amp castle creations esc
gws pico servos
sport/speed set up will have 1/8" pultruded rods for spars on LE and across span mid chord.
covering is tba at this point.
|Apr 04, 2008, 07:39 PM|
gen pics out of box
here are the pics of the wing out of the beds and laid out to see the planform
The leading edge and white foam is cut nicely, no divits no drag lines no burn marks. top notch cutting.
|Apr 04, 2008, 07:47 PM|
how to handle cores
for the newbies . . . .. do not throw away the "extra" foam from the cores or core beds!
o.k. those that have never made the mistake - your too good . . .or someone told you!
Until you cover the plane and are completely finished building - use these to cradle you foam wing to keep it flat and clean - no divits no cuts no damage!
you will need these to ensure that you have the wing flat to join it, to ensure that the leading edge is flush with the foam and to help you keep the wing still while you are cutting into and on it!
mark the center or each core with a T for Top of each core and an R and L so you know which is which. I have seen so many folks show up to fly with an upside down airfoil it isn't funny. Too much work to fix too.
So look at this pic and learn from one who has learned through the mistakes of others!
|Apr 04, 2008, 09:35 PM|
check the cores for damage
remove the cores from the bed and set the top and bottom pieces of the "bed on the table flat.
Inspect the cores top and bottom for any damage.
arrange the core beds facing out toward you.
|Apr 04, 2008, 09:46 PM|
apply glue to epp leading edge
Place a sheet of wax paper between the core and the core beds.
Make sure you have the Right Wing half with the Right EPP leading edge and the left wing half and the Left EPP leading edge arranged.
on the epp leading edge, apply glue (I use the uhu here) in a zig zag pattern with about a 1" tooth from top to bottom inboard to outboard.
Using a latex glove, rub the glue into the face of the leading edge of the core evenly spreading the glue.
apply the same glue to the leading edge of the core making sure that you have NOT mixed left and right sides AND make sure you apply and spread the glue evenly using a latex glove to protect your finger.
Let the glued sit for two minutes then slide the core back into the bed by 1/8" and use the ledge as a base to apply the leading edge to the core.
Apply even pressure and then place the top of the core bed (thicker inner part) over the top of the joined core and leading edge in the same manner as the bottom. The EPP Leading edge should be extending past the core bed but the core bed should be applying pressure to the top and bottom of the joint.
Use your hand to apply even pressure to the leading edge front to make sure you have a good joint.
Place a few light weights on top to keep pressure while you wait about 10 minutes for the glue to cure enough to move onto the other half of the wing.
|Apr 07, 2008, 05:38 PM|
remember, it is imperative that you use the very edge of the core bed as a support/guide to ensure that your leading edge is not drooped or raised above the appropriate line. This mis formation of the leading edge would drastically degrade the performance of the airplane!
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