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Feb 06, 2018, 10:08 PM
Held by Grace
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Build Log


While recently looking over my stable of slope ships I concluded that I did not really have a good 48" wing for front side fun and combat.
I have decided to build a Knife Edge wing produced by G.E.M.S {The guy's from Cleveland } ,They can be found at -

I thoroughly enjoyed building one of their other kits this past December, the Sizzle . its build log can be found here -

Here we go - The Knife Edge
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Feb 07, 2018, 08:13 PM
Held by Grace
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The kit revealed

I have to confess I tend to feel a mix of anticipation and anxiety when starting a new project.

The joy of spending time and effort to craft something that leaves a bit of yourself in it, learning new methods or materials, completing and flying your newest creation....

The anxiety : Oh no what have I gotten myself into...i haven't worked with this stuff before... never seen paint do that ! Boy did I screw this up ...I thought I had the CG in the right spot...
The list could go on and on .


Opening the Knife Edge kit I found a super complete package of components :
CNC cut EPP foam wing
Copolymer spars pre-installed in the wing
G.E.M.S spar wing joiners
pockets for the : Servo's, battery ,recessed push rod tubes and receiver compartment all pre- cut
Dubro control horns
coroplast wing tips and radio hatch
Aileron push rods and fittings
Balsa Ailerons.

You supply :
a receiver
2 -standard servos
1100ma life battery
strapping tape
fiberglass hinges
a on/off switch or switch jack {if you use one}
and your choice of covering materiel {Solartex, econokote,Ultrakote, laminating film ect. }
Last edited by BDOG1; Feb 08, 2018 at 07:36 PM. Reason: larger battery
Feb 08, 2018, 07:57 PM
Held by Grace
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Due to the high degree of prefabrication,the only cutting required should be slight trimming of the servo and battery pockets to fit your specific gear and trench for the servo wires.

Here is the starting weight of all the kit parts before starting
Feb 08, 2018, 07:58 PM
Held by Grace
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And the radio gear
Feb 08, 2018, 08:13 PM
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First step in the assembly was to glue the bottom wing beds together on a flat surface with your choice of adhesive, I used hot glue.
These will assure proper alignment when next you glue the 2 wing haves together.

Next cover the center of the wing beds with wax paper to prevent accidentally gluing the cores to the beds when you join the wing.

Now its time to glue the wing together.
Remove all the pre-cut pieces before gluing,no need to have to cut them out a second time
I am using hot glue so this step will go quickly,if you use something with a longer curing time you should use weights,tape and pins to assure alignment while the glue hardens .
Feb 08, 2018, 08:28 PM
And Repairs
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Having pre cut servo holes and gear compartments does look helpful. Unusual for an EPP kit.
Good luck with the build and thanks for posting pics.
Feb 08, 2018, 08:50 PM
Held by Grace
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Once the wing haves are glued together and dry its time to add the G.E.M.S spar joiners.

Trial fit the joiners in theirs prospective locations,
Push them to the bottom of the pre-cut channels -they should not stick out above the wing surface, you do not want to try and have to sand them down.

This is probably a good time to talk about the G.E.M.S spars and joiners as they are different than anything I have seen else where.

The spar is a copolymer material that has the ability to flex when it takes a hit and the return to its original shape rather that shatter.
The joiners are a tempered steel rod encased in a fibrous outer shell,

There is a old saying "Blessed are the flexible,they shall bend and not break" I think that sums up the design philosophy

I know this stuff is different from what most of us are used to working with,but i have seen these planes in action and this stuff works.

*A NOTE - if you are planning to DS the Knife Edge wing let the Guy's at GEMS know when you order and they will provide a different set up.
This combat set up has been DS'S to 70mph after that it can start to flutter.

Back to the build -
I am using hot glue for this build , going for a quicker assembly and nothing too fancy for the is a combat wing after all

Here you see the joiners glued in while resting in the beds, first the top and then the bottom
I used a small screw driver to push and hold the joiners in while the hot glue set
Last edited by BDOG1; Feb 09, 2018 at 07:54 PM.
Feb 08, 2018, 08:52 PM
Held by Grace
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Thank You Ty.
Yes with every thing all ready cut out its almost a arf

I saw you video of the Eagle "Sky Dancing"
It was Awesome !
Last edited by BDOG1; Feb 08, 2018 at 08:56 PM. Reason: more
Feb 08, 2018, 08:54 PM
Held by Grace
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Time to check the weight of everything up to this point
Feb 09, 2018, 08:03 PM
Held by Grace
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I have put a light skim coat of Spackle from the leading edge to behind the spars,I believe that the mechanical advantage gained with a smooth surface for your adhesive to grip is worth a little sanding.
While the spackle is drying I will pin the ailerons together and match sand and true all the edges .
After that I can mark the hinge locations and begin to slot them for the hinges .
Feb 09, 2018, 10:18 PM
Registered User

Look easy

Looks like it's going together pretty fast
Feb 10, 2018, 07:51 AM
Registered User
there are tunnels in the core for the servo wires and also for the battery to rx no need trench channel for the wires.
Looking great so far.
Last edited by dvk44039; Feb 10, 2018 at 08:09 AM.
Feb 10, 2018, 10:28 AM
Held by Grace
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"there are tunnels in the core for the servo wires and also for the battery to rx no need trench channel for the wires." - G.E.M.S
WOOPS - missed that
Bipe22 - Yes it takes me longer to write and take picture than to build

I am certain that if I destroyed one {if that is possible} away at a event I could put a new KE together over night in my hotel room and be flying the next day.

Next : Hinges
The tunnels -
Last edited by BDOG1; Feb 10, 2018 at 04:15 PM. Reason: more pics
Feb 10, 2018, 06:52 PM
Held by Grace
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I have now sanded the skim coat of spackle and thought it would be appropriate to see how much she weights now .
I have not kept track of this in the past but it should be a good point of reference for future builds
Feb 10, 2018, 07:14 PM
Held by Grace
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1 oz gain from filler does't seem too bad.

I centered my servo arms in preparation for the installation, pictured here is a servo tester from Hobby King/Turnigy .

If you don't have one of these you really need to pick one up.

I use them to set up and test direction on electric motors ,cycle my receiver batteries and of course check throws and operation of my servos.

Also shown here are my servo arms cut down and ready for installation

I am going to use Futaba S -148 standard servo's for the Knife Edge

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