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Sep 15, 2019, 02:34 PM
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UpNup's Avatar
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DIY? Change the wing fuse connection


Looking for some advice. Plans for the middle of the fuse don’t match plans for the wings. P-51B Pony in Aerofred. Electric conversion 57” WS. (.46)

1. Middle section on the fuse is 1/2” narrower than the dihedral braces on the plans for the wings.
2. Plan for the rectangle between the wings has spars that don’t match up with the fuse or the wings.
3. Wings are 2.5” thick at the wing root. The middle of the fuse is 1.5” thick. Can the wings be flat at the bottom and ride up the side of the fuse?

Does anyone have good plans for a P-51 at the wing-fuse connection? I’m willing to scratch build, but not if it exists elsewhere.
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Sep 15, 2019, 05:01 PM
B for Bruce
BMatthews's Avatar
Keep in mind that a lot of the plans out on the web are not all that complete in terms of stuff like this. A lot of them are more "guidelines" done by the original draughtsperson and that they filled in stuff like this on the fly when they built the first model and expect anyone using their plans to do likewise.

I don't feel that it's ever a good idea to cut into the wing center area to fit the fuselage other than for some small notching in the leading edge to allow fitting up close to a bulkhead for a holding dowel or the like. I would not want to put a step down in the wing's thickness like you seem to be planning on doing. Instead I'd modify the fuselage to accept the full wing thickness instead. That maintains the most wing strength... which is often and very typically more important than a little bit of fuselage side stock.
Sep 15, 2019, 05:38 PM
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Quote:
Originally Posted by BMatthews
Keep in mind that a lot of the plans out on the web are not all that complete in terms of stuff like this. A lot of them are more "guidelines" done by the original draughtsperson and that they filled in stuff like this on the fly when they built the first model and expect anyone using their plans to do likewise.

I don't feel that it's ever a good idea to cut into the wing center area to fit the fuselage other than for some small notching in the leading edge to allow fitting up close to a bulkhead for a holding dowel or the like. I would not want to put a step down in the wing's thickness like you seem to be planning on doing. Instead I'd modify the fuselage to accept the full wing thickness instead. That maintains the most wing strength... which is often and very typically more important than a little bit of fuselage side stock.
Thanks for the cautions. However, this is no center to the wings. Here’s the wings together with just the dihedral braces. And another photo is of the side pieces that are inside the fuse sides—and also gaps the wings by 1/4”.
Sep 16, 2019, 11:01 AM
B for Bruce
BMatthews's Avatar
I'm looking at the preview plan at Aerofred and what I'm seeing is a rather different way of making the wing and center section. It uses two panels and a rather odd center tray to connect the wings and allow them to be removed from the model for working inside and transporting the model. But that's OK.

What you mentioned is that the wings don't seem to fit closely enough to fit cleanly to the side of the fuselage. This may be due to a couple of things. First is that it is an error by the original designer that did the plan.... it happens..... Second is that the wing plan may have printed out at a touch larger scale than the fuselage.

At any rate you've gotten to where you are now. So it's a question of how to fix the issue. Since it's a gap I'd say just fill it with a balsa rib thick enough to fill the gap. Make it a touch oversize and sand it to blend with the rest of the wing's root area. Or if the dihedral braces are not glued in place yet (and I hope not since you need to slide the tray over the braces) then perhaps make new ones which are a little shorter so the wings close in a bit?
Sep 16, 2019, 02:23 PM
Registered User
My .02 worth:

On full scale P-51's the left/right wing panels bolt together at centerline rib, then as a single unit, the who;le wing is bolted to the lower lonerons where the front/rear spars pass below. Via stand off fittings, when the wing is bolted on, there is a gap between the top wing skin surface and the fuselage sides. This gap is hidden by non-structural fillets. Also, only the forward fillet is of compound curvature and is actually part of the lower aft engine side cowls. the middle and aft fillets are single curvature (rolled flat sheet). The aft fillet has a lower portion which is also single curvature and top bottom pieces are welded together at the their tE's. The shark-fin like triangular piece, jutting upward on top of the aft fillet actually covers the longeron jog introduced to lower the wing 3", when Merlin was adopted. P-51A and earlier wings sat 3" higher than B/C/D models.
The lower wing surface also forms a " bottom of the fuselage" and incorporates the wheel bay doors and the area just in front of and above the radiator scoop inlet. There is a fillet attached to the radiator fairing that forms the "gutter" between the bottom surface of the wing and the radiator fairing, proper.

It's been my observation that scale model designers oft resort to "simplification efforts" that actually result in model features and shapes that are actually more complex than the original!

Some of my(and others!) scale drawings and observations have been posted here:
https://www.rcgroups.com/forums/show...volved-only%29
Sep 16, 2019, 04:53 PM
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Thank you BM and PP You’ve given me lots to review and think about. Thanks for affirming that this is a challenge and I’m not completely crazy!
Last edited by UpNup; Sep 16, 2019 at 06:41 PM.
Sep 17, 2019, 11:10 AM
Registered User
I'm afraid the sanity boat has already sailed! I am a certifiable airplane nut.
Sep 17, 2019, 08:48 PM
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UpNup's Avatar
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Quote:
Originally Posted by packardpursuit
I'm afraid the sanity boat has already sailed! I am a certifiable airplane nut.
And least a knowedlegeable one.
Sep 23, 2019, 11:16 AM
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Took steps to build the tray. I’m using 1/8” basswood. I’ve got to make braces between the “tray” under the fuse and the wing root.

One unexpected slow-down is moving my workbench to the middle of the room to accommodate both wings.
Sep 23, 2019, 02:07 PM
Registered User
"Moving the workbench"
which is why I made my 30" x 96" ,near perfectly flat work top bench, mounted on castors. But I've got no garage shop, now. And it wont go down the narrow hall of the mobile home, where I'll set up shop soon. Funny how we went from a one bedroom apt, over a great two car garage, to a 4 bedroom double wide MH and no garage. At least my new shop, in the master bedroom, will have it's own shower and toilet. It also has all of my tools and balsa stash, EVERYTHING. We only live in the front half of the house and still have too much room! My roll around bench sits outside under the awning and wrapped ina tarp. full of garden tools. I will try to sell it in the Spring.
Sep 29, 2019, 02:10 PM
Who are these that fly?
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Finishing the center wing tray


Just a quick note to thank guys BMathews and Packardpursuit for giving me some counsel about creating a tray or box to join the wings. Lotsa balsa and plenty of basswood in that little tray. Not finished, but past this hurdle.

This was custom-built because the plans were far off. I was given good advice to complete the wings and fuse first.
Last edited by UpNup; Sep 29, 2019 at 02:17 PM.
Oct 01, 2019, 02:03 PM
B for Bruce
BMatthews's Avatar
Looks like you chose the options and details yourself. Packard's and my posts mostly just triggered you to get creative and perhaps past a mental block you might have had from what I see. I see a whole lot of your own options and work here. So well done on all counts.

And yeah, there's much to be said for having the main working surface as an island in the middle of the area... provided you have that sort of room to work with. Not everyone does. But when you can it's solid gold.

I really like having the side bench done to kitchen counter like specs for the small stuff and as a staging area for tools and small bits when working with the center island. Before when I had the whole shop in a two car garage my "island" was a piece of plywood thrown onto the table saw. It worked well actually.... especially once I learned to put some temporary drywall screws up into the underside to stop the plywood slipping around.... No models were harmed but it did make my heart skip when I leaned against the edge and fell forward with visions of landing on the model while plywood, model and I all went to the floor in a heap... But like a good cartoon it all came to a creaky stop and I was able to recover instead of holding up a sign that said "OH OH!" just before falling to the canyon below.....
Oct 07, 2019, 11:45 AM
Who are these that fly?
UpNup's Avatar
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The final version sanded and hit with light spackling. I tried to do as much as possible with the tray on the plane.

I added a scoop to extend the P-51B a half inch longer then the plans called for.


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