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Oct 25, 2018, 11:00 PM
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Build Log

Building a 70" F4U-Corsair


I recently started this large undertaking (in my opinion) after watching a giant scale airplane fly indoors at slower speeds than I could've ever imagined. So, of course I wanted to build my own. I went on Aerofred and found some plan for a corsair that I thought could work and downloaded them. I then used the free version of Adobe (I forget the actual name of it, I'll post its name if I remember) to tile the plans onto multiple sheets of paper and scaled it up to around 15-20" on the wingspan. I taped all of the sheets of paper together (like 48 of them) so that I had a large sheet of plans like the ones they give you with a balsa kit. I went to the dollar store and bought $12 worth of foam. I'm using this foam because it is some of the lightest and cheapest stuff you can get, and it's a lot easier to cut through than the Elmer's and other heavier brands. Another thing I want to try is make a watered down glue solution and make a rigid skin on the plane to add durability. I might experiment with getting the paper that's already on the foam saturated in glue for this skin effect, or I might peel it all of of the outside of the plane and do it with some blank newspaper (there's an article on rc groups about this method). So today I first started building and I am, instead of using a bunch of ribs, I'm just going to make two spars out of foam(one might have some carbon fiber in it) and just a couple of formers to bend the foam around for the leading edge. I started on the main spar, using the cross section as a guide I poked some holes from the top of the plans through the first layer of paper in the dtfb. I then connected the holes with a streightedge and freehanded the rounded wingtip. Then I made it so that it will fold into a box using some of Flitetest's 90* folding methods. All of the pictures of things I described will be below.
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Oct 27, 2018, 07:58 PM
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Day 2-3


Yesterday I drew and cut most of my formers for the leading edge of the wings. I only had two actual ribs on the plans that I could trace, so I had to freehand many of them to get the tapered effect of the wings. Today, I drew and cut all of my trailing edges using the same techniques as the leading edges. I then glued all of them to both of the dihedral parts of the wings. I made a bunch 90* triangles for gluing on the ribs so that I could get them straight/perpendicular to the main wing spar
I worked a total of 5 hours today, 1 Hour yesterday, and 2 hors the day before.
Oct 28, 2018, 05:13 PM
Build straight - Fly twisty
Whiskers's Avatar
At what stage are you building the 'crank' into the wing?
Oct 28, 2018, 05:35 PM
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Do you mean the wing folding or do you mean the bellcrank? If you mean the bellcrank, I'll place it just behind the spar and punch my control rod through the foam ribs. If you mean how the wing folds, I'm still working on that in my head, but I think I'm going to use a push/pull solenoid for the locking pins and a servoless retract system for the actual motion.
Oct 28, 2018, 05:44 PM
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And, hey! Thanks for reading my posts.
Oct 28, 2018, 09:41 PM
Build straight - Fly twisty
Whiskers's Avatar

I was referring to the characteristic cranked shape of the wing as shown below.
Oct 28, 2018, 09:53 PM
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Anhedral wing


So today I finished the skeleton for the anhedral parts of the wings. It went together basically the same as the rest of the wing. For my main spar in this section I built a box With a little bit larger dimensions than the rest of the wing. I built a simple box and then I measured the angles that I needed to cut and sawed them off with the bandsaw. They turned out very well if I do say so myself.
I worked a total of 1.5 hours today (I work pretty slowly if you haven't noticed yet).

Thanks for reading!


P. S.
I didn't see your post, so this is the anhedral part of the wing (opposite of dihedral)
Last edited by Luke Rondeau; Oct 28, 2018 at 09:55 PM. Reason: Needed to make a change
Oct 28, 2018, 10:25 PM
Build straight - Fly twisty
Whiskers's Avatar
Ah! Good!
The correct look of the wing is so important to making the model 'right' in the air.
Oct 28, 2018, 10:40 PM
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Yes, and I want it to be (somewhat) presentable up close
Oct 28, 2018, 11:51 PM
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Looking good! At 70 inches this thing is going to be awesome.
Oct 30, 2018, 07:18 AM
Ldm
Ldm
Ldm
Ldm's Avatar
Subscribed -very cool
Nov 02, 2018, 07:35 PM
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Catching up


Sorry for the lack of posts as of recent, I've been busy with quarter finals this last week at school. But I have made a little bit of progress on the wing. I finished the very center section that rests just below the fuselage (you may notice that the spars in each section are a little different, I didn't do this entirely on purpose, but it shouldn't effect the functionality or I think even the look of the finished plane). I also started drawing and mapping the center piece of the fuselage. I'm making one "rib" that is going down the very center section of the fuselage. It needs to have a seam because my foam board isn't big enough. I'm going to use one of Flitetest's methods using packing tape and hot glue for this. I'm then going to make ribs that go perpendicular to this piece in similar fashion to how I made the ribs for the wing. I don't think that I've described how I do that so I'll give that a go. If you'll look at the picture of my full plan, you'll see that there are only a couple of actual drawn ribs. So I cut that shape out of foam board and use it as a template. I measure how long my new rib needs to be from the top view of the plans and then measure how tall to make them from the cross section. Then I line up my other rib to my dimensions on the foam and freehand the new one following the other my template one(ask for clarity if you don't understand).

*whew! My thumbs are getting tired! I'm almost done though*

So I've got another build tip that I came across while building. When you make your A or B joints like Flitetest's, you can fold both halves of the foam back and then to remove the center cube just push sideways with your finger nails against the foam. This shears it from the paper leaving a perfectly clean surface for a strong glue joint.

Thats all for right now, this took me just 1 hour, I'll leave pictures of what I did below. As always, thanks for reading, thanks for the positive feedback, and happy building.

P. S.: actually I lied, I'm going to post the pics later bc I'm using data right now.
Nov 03, 2018, 07:00 AM
Ldm
Ldm
Ldm
Ldm's Avatar
Keep up the good work , remember the important thing about building is build at your own pace . Don’t worry about the thread, when we subscribe it updates when you do . No worries .
The best way to build a great model is to work have fun build when you want , when your tired bored stale , walk away until another day !
Nov 03, 2018, 08:41 AM
I Look, Listen, and Learn
Timbo383's Avatar
I'll be watching this build.....with patience...
Nov 06, 2018, 05:59 PM
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The fuselage


Hey everyone, I'll put the pictures from my last post below and a few new ones. So after I finished the wing skeleton, I started in on the fuselage. This piece needed two boards of the foam because it is so big, so in the close up pecture you can see how I connected them. I used one of flitetest's methods where they put tape on one side of the board, then fold it backwards and fill the cavity with glue, they squeeze the boards together, wipe off excess glue and then tape the other side... it's very sturdy. I've also cut out all of the ribs for either side of it. I've finished with the fuselage ribs on one side of the main part and I'm just about to put them on the other side. This is where it gets exiting! I would try to put my servos and extension rods and such in at this point but I don't have those electronics and I'm debating some things about the tail end section. So while I'm waiting for that to happen I'm going to go ahead and put all of my ribs on the other side (it's gonna look cool). This is about 2 hours of work, now that I know what I'm doing it's going much faster..

As always thanks for reading and happy building.


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