My first design

Ask other modelers for a little help / knowledge ?

Postby Xanadu » Thu Apr 28, 2011 10:08 pm

A word of warning about the motor box design.

The Great Planes motor box design is flawed, and will separate from motor vibration, etc. You will need to reinforce the box with fiberglass and epoxy.

There is a tech note on the GP site about this flaw, and how they recommend repairing it.
I also know of this flaw first hand, as I have the GP ASF of the DR1. Kept breaking the mount until I did the fiberglass and epoxy repair.

There is even a video of the this actually happening during flight about 1/2 way down the linked page.
http://www.rcgroups.com/forums/showthread.php?t=657521

I would like you to seriously consider reinforcing the motor box.
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Postby scigs30 » Fri Apr 29, 2011 12:08 am

Xanadu, Most of these ARFs fail because of poor glue joints, and from what I read, that is the case with the Fokker. Great Planes recommends using thin CA to reinforce the glue joint, another bad idea. Wood glue or epoxy should be used on a plywood to balsa wood joint, hot glue and CA is a poor choice. The few pictures I have seen of the failure is a failure of the joint and not the wood itself. I take it a step further and brush Epoxy on the motor mount just like we used to with the old RC Gas planes. Thanks for the heads up, I will also take a second look at the design.
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Postby Xanadu » Sun May 01, 2011 8:44 pm

I used epoxy and fiberglass strips, making it pretty much bullet proof now.

One thing I did find, was there was not quite enough meat on the face plate, too many holes weakening the structure making it prone to cracking. I epoxied and glassed the front as well. The extra weight it added was not even noticeable with the power the Rimfire motor provided.
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Postby scigs30 » Sun May 01, 2011 11:13 pm

To date I have not owned an ARF, not do I plan on it, too many kits out there to build. I have seen plenty at the flying field since that is all anyone ever flies and they all have the same issues. The covering looks great at 5 feet but up close there are som obvious issues, but not a big deal. The biggest thing I have noticed is that it appears the plane is put together dry then glue is added, not an effective glue joint. I used wood glue on my mount followed by Expoxy reinforcement and spruce braces, so that should be strong enough.
I have most of the build complete with some minor adjustments and final sanding. I will also go back and make the necessary adjustments and measurements to the plans and parts. The Great Planes parts fit well and you can see from the pictures my complicated wing jig, duct tape and clamps.
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Postby Supercubber95 » Sun May 01, 2011 11:41 pm

No words to express...
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Postby ADW 123 » Mon May 02, 2011 2:52 pm

how much did the R/c equiptment cost for that?
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Pilot

Postby B R Burns » Fri May 06, 2011 5:30 am

:?: Can you tell me where to get the little pilot from, Please. B R Burns (Barrie) I am in the U.K.
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Postby jim » Sat May 07, 2011 2:52 pm

absolutly amazing
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Postby Bargle » Sat May 07, 2011 11:06 pm

Looks great, Scigs. :D
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Postby supercruiser » Sun May 08, 2011 10:09 am

Fascinating to look at.
I noticed your wing spar construction. That is the proper method for building up a wing: upper and lower spar caps, joined by shear webs on the inner section of ribs.
I really like the looks of how you built the vertical fin/rudder. 8)
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Postby Squishyp38 » Sun May 08, 2011 11:37 am

I may have missed this, but did you make the plastic parts like the cowling yourself?
The P-38 is arguably the best... Forget that, it is THE BEST fighter of world war two, and is epically AWESOME!
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Postby scigs30 » Sun May 08, 2011 9:10 pm

RC equipment can be cheap or expensive. A lot of the guys at the flying club are buying cheap rc gear from Hobbyking. Radio, receiver, batteries, servos, ESC can run 100 to 500 dollars depending on the quality and personal preference.
The pilot and plastic parts were bought on Ebay, Great Planes makes the parts for their ARF.
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Postby scigs30 » Mon May 09, 2011 2:44 am

Tonight the family left so I was able to finish the Fokker minus some screws I still have to buy. Without electronics or motor she weighs 12 ounces. Cannot wait to take her out for a test flight. My Nieuport design is at the cutters right now, can't wait to get started on it.
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Postby Supercubber95 » Mon May 09, 2011 8:46 am

OH OH OH :shock: :shock: :shock: WOW WOW WOW :shock: :shock: :shock:
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