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Author Topic: 3DR1 Fokker Triplane  (Read 1265 times)

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Offline Flypaper 2

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3DR1 Fokker Triplane
« on: September 29, 2016, 11:26:27 AM »
The idea behind this was, an aerobatic 3D type plane. I figured with a short span with lots of wing area would fill the bill. Don't get much better than 3 wings. :D
 Light weight was one of the other criteria. That's where this foam from Home Depot pays off. It's normally used for under floor insulation. It has a film of thin plastic on either side.
 It's only very roughly semi scale. I wanted to be able to fly at very slow speed too, so I made the control surfaces oversized to enable that.
 Bottom wingspan is 26 in. span.
 Middle span is 30 1/2
 Top is 36 in. not counting the ail. outer tabs.
 The total ail. span is 38 1/2 in.
  Wing chord on the bottom two wings is 8 1/2 in.
 Top wing outer is 9 1/2 in. inner part is 8 1/4.
These numbers are not critical. 1/2 in. either way is not going to matter. One of the joys of scratch building. ;D
 Fuselage is 5 in. deep and notched out for the bottom wings.
Length is 24 in.
 This one turned out a little nose heavy, so I'd move the wings back by 1 in. So the bottom wing will be 4 1/2 from the firewall. Middle wing is 3 1/2 in.
 Now, if you put a ruler between the bottom and the centre wing, the top wing leading edge will be in line with the two bottom wings. Wings are about 4 in. apart.
 Here are some pics. If you need anything specific, let me know.
Rudder hinges have very little area so I used the heavy nylon hinges with the brass cotter pin that you would normally find on the larger 1/4 scale planes.
 I think everybody knows what the tail skid is.
 I forgot. The motor is a BP 2217-7T and 1250 KV and sold by Leading Edge.
 By the way, the plane weighs 1 lb. 2 oz. W.O. batt.
« Last Edit: September 29, 2016, 11:35:35 AM by Flypaper 2 »
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #1 on: September 29, 2016, 04:44:00 PM »
This plane flies like it is on rails and follows the sticks as thought it was reading your mind. I was so impressed when Gord let me fly it, I started building my own. Foam is cut, assembly next. If anyone wants plans, I could figure out how to copy the templates. Easiest just to borrow them.
Photos to follow.
« Last Edit: September 30, 2016, 12:54:01 PM by ganguy »
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #2 on: September 30, 2016, 12:53:34 PM »
Gord:
Are all your servos 9gm, or 5?
I've cut and glued most of the foam. Here's the "Fokker-Werks"
« Last Edit: September 30, 2016, 12:55:25 PM by ganguy »
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline Flypaper 2

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Re: 3DR1 Fokker Triplane
« Reply #3 on: September 30, 2016, 01:32:52 PM »
All 9 gram Reg. Looks like you might be needing a bigger workbench. ;D
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #4 on: September 30, 2016, 03:36:41 PM »
Gord:
Those doublers, do they go all the way back to the TE of the midwing?
And did you put any spars in the wings?
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline Flypaper 2

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Re: 3DR1 Fokker Triplane
« Reply #5 on: September 30, 2016, 04:10:40 PM »
The doublers go to the leading edge of the bottom wing. There no spars in the wings. The only strength is through the carbon rods that go through outer wing struts. They go through the upper and lower wings to the outer surfaces. They're about 1/8 in. dia. or 3mm.
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #6 on: September 30, 2016, 07:31:55 PM »
Thanks Gord, I'm getting there slowly. I'm also going to make the wing struts larger as you suggested.
The joining worked out well., but I might put a bit of rod in the upper wing.
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline Flypaper 2

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Re: 3DR1 Fokker Triplane
« Reply #7 on: September 30, 2016, 07:52:34 PM »
The upper wing didn't have enough support due to the narrowness of the centre strut, So, this morning I put a carbon rod through the wing and into the fuselage, at the back of the wing. I cut around the foam where it goes through the wing and fuselage. Sort if a tapered hole. then filled it with hotglue. The wing will bend no more. ;D
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #8 on: September 30, 2016, 08:00:02 PM »
Hot glue saves the day again!
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #9 on: October 01, 2016, 07:56:22 AM »
So, what do you think about making the struts a bit wider to help with the flatness across the chord? I'll post a sketch.
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline Flypaper 2

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Re: 3DR1 Fokker Triplane
« Reply #10 on: October 01, 2016, 08:21:12 AM »
That's more like what I should have done. I did more like that on the smaller one I have, that this was copied from, other than they are curved at the front also.
 The carbon rods are to tie the wings together for stiffness, so they won't bend, as in unwanted dihedral in a tight loop.
With the longer glue surface that you have, may not need them. If they are needed, they would be easy to install later.
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #11 on: October 01, 2016, 08:37:46 AM »
Thanks Gord - I thought it might be too much weight.

I'm just working on the tailplane now. You are right, that hinge has to be super strong, and I might put a light carbon rod vertically for extra stiffness.

Contact cemented the doublers in, and I'm looking around for an engine.

I wonder if Gary has a neat way to hot wire the leading edge so we don't have to cut and sand?

This plane is fun to build! I can hardly wait to get airborne.
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline Flypaper 2

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Re: 3DR1 Fokker Triplane
« Reply #12 on: October 01, 2016, 09:13:22 AM »
Sort of like building an indoor flier on a slightly larger scale.
 Where else can you cut out/build a 3 ft. wing in about 3 mins. ;D
Gord
Hotglue, held together with foam.

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #13 on: October 01, 2016, 12:27:05 PM »
Well, due to my dumb error, it was more than 3 minutes, but I take your point.
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"

Offline ganguy

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Re: 3DR1 Fokker Triplane
« Reply #14 on: October 01, 2016, 01:41:45 PM »
Elevator - Gord did you double bevel that like the rudder?
Churchill said: "Success is a series of failures during which one does not lose enthusiasm!"