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Old Feb 01, 2013, 10:17 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
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Quote:
Originally Posted by demondriver View Post
...Use light weight spackle to smooth your Wingbox wall when your done.
Great video DD, I'll certainly take this approach as I get closer to completion.
Kevin
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Old Feb 01, 2013, 10:40 PM
KFC
Blue Foam Master!!!
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United States, KY, Hanson
Joined May 2007
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Quote:
Originally Posted by Eddie P View Post
That's a pretty rare case, such a design, isn't it? You have me curious now If you lost an engine in this "prop near the wing tip" configuration, the model might essentially be almost uncontrollable with the thrust line so far out laterally from of CG via P factor (unless you went inverted to bring the P factor in toward the center line ). Are you talking TiltRotor stuff?
not Tilt rotor (most tilt rotors don't utilize a low aspect ratio wing), but the Chance-Vought xf-5u utilized the configuration. I built one a few years ago. Interesting airplane.

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Old Feb 01, 2013, 11:27 PM
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St.Catharines, Ontario
Joined Jan 2009
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I've seen as large one of these flying at a local show. it flew very well. never did it see it fly with an engine out though. would have been interesting for sure.
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Old Feb 02, 2013, 12:17 AM
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The Flapjack! I immediately thought of this in my head when I read your post but immediately figured, "no, that's not what he meant... couldn't be..."

Very cool.
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Old Feb 02, 2013, 06:44 AM
A Day @ a Time - Matt. 6:25-34
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North AL, USA
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Nice picture KFC! That one looks inherently unstable. I guess now I know a bit better why you don't see many aircraft with engines way out on the wing...

This is good stuff guys, keep it coming!
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Old Feb 02, 2013, 09:17 AM
A Day @ a Time - Matt. 6:25-34
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North AL, USA
Joined Nov 2009
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Good Day,

Since the basic wing box is complete (although not attached with bolts) I thought I would lay the E205 airfoil over the side to have a look at what I've got.

This airfoil is an 8.5" chord x 1.25" thick, representing 14.7% thickness. Regarding the airfoil, some of you have commented it appeared to not have as much thickness below the center line. So, I went out and did a search on the E205 and all I have seen look like the one in the picture. Feel free to chime in on this shape, although I'm still learning TLAR will get you in the ball park so this may be OK for this application.

I think laying the main spar on some thin ply in the wing box will work out fine. I'll be making up a narrow profile of the airfoil shape to help me get the AOA correct. I won't do any detailed work on this until I get the wing box in the fuselage and mounted properly - I don't want to set an angle now to find out later that the mounting on the fuselage has either increased or decreased what I built into the wing box.

The tricky part will be the rear where I have the rear balsa piece coming into the wing box. With the FFF covering it may be a challenge to get this piece into the wing box because of the thickness. I'll lay this out to scale too and sort out how to do that. I may find that I do not want as steep a transition of the top of the airfoil so I'll have a bit more thickness to work with. Does that pose any risk to the performance of the airfoil? I picked up some trailing edge stock from one of my FBs and plan on using it. I got the biggest he had (haven't measured it yet). I'll need to get the rear of the airfoil in front of the flaps close to the height of this stock, at least inboard of the nacelles.

Anyway, 'nuff from ruff... Off to work - IT Guy has to sort out some stuff (sorry guys, I don't have a cape but a Director I worked for about 20 years ago gave me a fireman's hat). I hate financial closing weeks!

Kevin
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Old Feb 04, 2013, 09:13 PM
A Day @ a Time - Matt. 6:25-34
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North AL, USA
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Well, haven't had a whole lot of time to work on the 4-0-4 in the last few days, including this evening. I did however snap a picture of the wing box end. The marks you see are the approximate outside of the fuselage, the seam between the 1 inch foam and the approximate location of the nylon bolts.

I picked up some 4x20 2 inch nylon bolts to use for mounting the wing. I used four of these on my Piranha (yes, that is probably overkill) but they work really well.

My idea is to french in some thin ply all along where the seam is marked with the sharpie. Cut out along the seam with enough gap to make it snug but not too tight. Use Gorilla Glue to glue the ply in. Use my hole cutter made out of antenna rod and drill out the foam from the bottom of the wing box to the thin ply. Use a regular drill to drill up through the ply and top layer of foam. I'll place some more ply above the wing box that I'll epoxy the nut to. Two on each end.

Does this sound OK? I haven't mocked up the ply in the fuselage for the nuts, but this shouldn't be very difficult to do.

Thanks,
Kevin
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Old Feb 05, 2013, 07:43 PM
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Quote:
Originally Posted by ruff1 View Post
Well, haven't had a whole lot of time to work on the 4-0-4 in the last few days, including this evening. I did however snap a picture of the wing box end. The marks you see are the approximate outside of the fuselage, the seam between the 1 inch foam and the approximate location of the nylon bolts.

I picked up some 4x20 2 inch nylon bolts to use for mounting the wing. I used four of these on my Piranha (yes, that is probably overkill) but they work really well.

My idea is to french in some thin ply all along where the seam is marked with the sharpie. Cut out along the seam with enough gap to make it snug but not too tight. Use Gorilla Glue to glue the ply in. Use my hole cutter made out of antenna rod and drill out the foam from the bottom of the wing box to the thin ply. Use a regular drill to drill up through the ply and top layer of foam. I'll place some more ply above the wing box that I'll epoxy the nut to. Two on each end.

Does this sound OK? I haven't mocked up the ply in the fuselage for the nuts, but this shouldn't be very difficult to do.

Thanks,
Kevin

Looks Good to me Kevin! Great work!
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Old Feb 05, 2013, 08:10 PM
A Day @ a Time - Matt. 6:25-34
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North AL, USA
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Thanks, not sure I'll get to it tonight, but next time I report back hopefully I'll have the ply installed in both the wing box and mounting points in the fuselage!
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Old Feb 10, 2013, 09:30 PM
A Day @ a Time - Matt. 6:25-34
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North AL, USA
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Found a nice web site for a guy named 707 - He just uploaded some Martin 2-0-2/4-0-4 Sketchup drawings! He has a great R-2800 cowling, several Martin variations, and a bunch of other airplanes in his collection. I'm definitely going to refer to this stuff, even have downloaded some of the models. He takes requests too.

Go check it out here.
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Old Feb 11, 2013, 01:16 PM
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Originally Posted by ruff1 View Post
Found a nice web site for a guy named 707 - He just uploaded some Martin 2-0-2/4-0-4 Sketchup drawings! He has a great R-2800 cowling, several Martin variations, and a bunch of other airplanes in his collection. I'm definitely going to refer to this stuff, even have downloaded some of the models. He takes requests too.

Go check it out here.
Great Site Kev! thanks for the link!
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Old Feb 17, 2013, 04:12 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
North AL, USA
Joined Nov 2009
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Wing Box Bolts Installed - Need Advice

Howdy,

After waiting much too long to get my 1/16 thin ply, I finally picked it up yesterday.

As documented in an earlier post, I inserted and glued two pieces of ply fore and aft between the 1 inch foam pieces, then measured and marked for the bolts to secure the wing. Drilled out the foam with my trusty antenna tube to the ply piece from the bottom, then enlarged the hole with a rat tail file so the bolts would fit. Took my 3/16 punch and knocked a pilot hole in the ply so my drill bit wouldn't wander. Drilled into the ply with 1/4" bit, trying to keep it as straight up as I could (a drill press would have been great) all the way through the top of the wing box. The nylon bolts fit into the holes and stay in place which is nice.

I have attached side, top, and bottom view pictures of the wing box with the fuselage sitting on it at just about the proper position. I'm looking for advice on how to reinforce and lay in some ply to epoxy the nuts. I have seen several of you take a few pieces of FFF glued in between bulkheads with ply glued to the bottom as a mounting point. I want to leave as much space open between the bulkheads for airflow as I can. Perhaps FFF sections running parallel to the fuselage profile spine and a ply strip glued to the bottom of that that is the width of the front and rear sections of the wing box?

I welcome any suggestions here, thanks.

Hope to pick up the pace on this build over the next week...

Kevin
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Old Feb 18, 2013, 05:05 AM
ich bauen groß modell flugzeug
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United Kingdom, London
Joined Dec 2010
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If yu want to thread the wingbox then coat your nylon bolts with vaseline, then fill the hole it will go in wit epoxy and then screw it in... And leave it to dry, then when i havs dried simply screw the bolt out of the hole and it will leave a nicely threaded hole
And seeing that you left the center of the wingbox hollow (to fit your esc's)
I'd add a few NACA ducts to aid cooling te esc's
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Old Feb 18, 2013, 05:10 AM
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Charelston SC U.S.A.
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Quote:
Originally Posted by Keenan smith View Post
If yu want to thread the wingbox then coat your nylon bolts with vaseline, then fill the hole it will go in wit epoxy and then screw it in... And leave it to dry, then when i havs dried simply screw the bolt out of the hole and it will leave a nicely threaded hole
And seeing that you left the center of the wingbox hollow (to fit your esc's)
I'd add a few NACA ducts to aid cooling te esc's
Not a bad idea K!
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Old Feb 18, 2013, 05:12 AM
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Looki'in Sharp, & really spot-On Kevin! Very Nice wing Box for your 404!

The Wingbox is the "Center-Nucleus" Of any wing so it needs to be strong.
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