Douglas TBD Devastator (oz2669)

 

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User comments

Hi, I do want to build this beautiful model. However I can not understand the design/drawings of W1 and W2 wing ribs. Can anyone comment about? Thank you.
Muzaffer Geçim - 30/07/2023
W2 is longer than W1 because it is angled in relation to the other ribs and wing chord. Hope this helped.
Douglas Babb - 30/07/2023
The reason W-2 is similar but longer than W-1 is because W-2 is positioned diagonally and meets with W-1 at the leading edge (see wing planform, point of view from the top). The top/front spar slot on W-2, which also has a higher degree angle, becomes correct when the rib is placed diagonally as its supposed to.
RC Yeager - 31/07/2023
Thank you for your comments. But I am already well aware of the locations of both ribs and hence the respective lengths of them. My question is about the inner features of these ribs:
Why are they drawn like that? They look like ribs in ribs? Very peculiar. Further more W1 runs almost tangent to the fuselage. But how can that ever be despite the formers F3 and F4 ? The deep belly slots under these formers are not deep enouh to allow thru passage for W1 s !
Whatever the Rosetta stone was for understanding the Egyptian hierogyps, W1 & W2 ribs are the key to understand this plan- I think.
Muzaffer Geçim - 31/07/2023
I studied a little with some measurement, to me it works but:
1- PB always made a great effort in lightening every model parts. Note the lightening holes in ribs w3 to w7.
2- There is no ribs on ribs; W1 and W2 are great enough to be realized by the “sliced ribs” method and reinforced in the leading edge nose area. Drawings are correct.
3- the notch on F-3 is only for the lower slice of W-1 ribs. And it’s visible the upper slice section.
4- Building: I must admit it’s the obscure part of the plan. Probably the wing is made starting by glueing ribs from w3 to w7 on the main spar and on leading and trailing edge, then glue only the lover slice f W-1. Join the central part of the main spar to the other semi wings, or better make it in a single piece, then glue the L.E. and T.E. respecting dihedral angle.
5. Once the (semi complete) full wing is ready, insert the fuselage on it in trough the notches for the lower slices of w-1 w-2. Then add the upper slices of w-1 w-2 and fairing support. PB didn’t mentioned in the plan a stiff paper fairing (rolled on pencil) thet goes from fuselage to w-2 since the L.E. triangular fillets (I presume). Pit
Pit - 31/07/2023
Dear Pit,
I deeply appreciate and thank for the effort you did for your comment. I do agree but still I have the following reservations:
( I wish we could post pictures here)
1 .- If w1 and w2 were sliced rib construction then how can the slots for the main spar shown on w1 and w2 can be drawn like that? They are drawn as if the inside of them were solid sheet too?
2.- height of the w1 rib ~14 mm at the F3 and ~13 mm at the F4 intersection. When we look at the formers upper sliced rib -as you call- can not be placed later either. They can not pierce thru the formers.
3.- the cross hatched features on the lower sides of the f3 and f4 formers corresponds to the strips shown just above the upper slice/sheet shown on the side view at the top of the plan. Careful measurements vindicate this.
4.- you say that Pres reinforced these ribs on the LE but I think it shows a gap in this area and the semi-round feature is the front end of the sheet inside?
Best Regards.
Muzaffer Geçim.
Muzaffer Geçim - 31/07/2023
Hi Muzaffer,
thanks, I noticed all you said and many more on this plan. In your order:
1-Surely w-1, w-2 have a spar slot that makes confusion and resemble a slot for a full rib, but probably PB wanted to indicate the position of the upper slices in relation of the main spar. I’m not so worried about it.
2-the lower slots in f-3, f4, are only for the lower w-1, w-2 slice rib and in f-3 deepest than the slice dimension due to wing incidence to reach. The upper slice do not pierce trough the formers (and it’s impossible), they’re applied later externally to the formers, like a normal stringer: see former f-3, f-4, f-5 in wich the unique dotted line in only filled notches makes it evident. All this zone is later covered by stiffened paper fairings.
I think sliced ribs solved most of the problems, but as I always say: “try to build, with the pieces in your hands it’s easier to find the correct solution, continuing to analize the plan make you see errors that do not exist (sometimes).”
Do not expect every plan 100% perfect as many OZ contributor demonstrated when effectively built them. PB plans, sometimes, seems a rapid sketches more than a “regular” plan. I built many Walt Money and other plans and I met little errors on them during construction.
I was a professional architectural scale model builder, famous architect commissioned us complicate model buildings and we discovered great errors in their drawings during model construction. I said that we had to be payed two times, one for the model an one for the “revision service” of their drawings.
Pit
Pit - 01/08/2023
Hi Pit,
Just back at home after Chris Nolan’ s “Oppenheimer” ; and I am pleased to see your comment again. Thank you.
I am convinced that the w1 & w2 are both of sliced rib construction. For w1 it is inevitable due to the related formers; but I think I will build w2 ‘s like the rest of the wing ribs perhaps two of them one of which glued against the former horn ends one as as root rib of the wing panel, we’ll see. Of course being aware that the wing dihedrals begin with the W1 s.
I do not want to extend this conversation any longer but I really can not help to ask the followings:
1. You said: “…they’re applied later externally to the formers, like a normal stringer: see former f-3, f-4, f-5 in wich the unique dotted line in only filled notches makes it evident. All this zone is later covered by stiffened paper fairings” However I can not see any dotted lines? At which view should I look? On formers themselves or at top or side views? Or do you mean dashed lines? Where are they?
2. If PB -or yourself- were to care enough to show the positions of the upper slice of W1 on F3 & F4 formers’ face on drawings below how would he draw / display them? As for PB, I am a great admirer of him. I have even got this plan printed and framed and hanged on the wall. May he live long and prosper. Thanks again indeed. Muzaffer.
Muzaffer Geçim - 01/08/2023
Here again with good (and final, I hope) news. Fortunately I found a build blog because sometimes it's difficult to me to clarify my thoughts in english.
As you can see this builder made some free variations to simplify his life, making w-1 full rib to place it on his own internotch or better sectioning (probable) the full rib to fit in interformers space. But it can be done slicing the rib as per plan to save weight. Ribs to ribs are an insult against PB concept of lightness. PB is one of mine preferred rubber powered designer too. Definitively a quite common building method in a difficult plan. Enjoy.
Steve, now you have some photos too.
https://ibb.co/album/bzqYLt
Pit - 01/08/2023
Hi Pit;
Thank you.
You’ ve been of great help to me.
Best Regards, muzaffer
Muzaffer Geçim - 02/08/2023
PBYACE appears to have constructed many beautiful models, the TBD Devastator being merely one of them. I salute his talent and skill.
Jan Novick - 02/08/2023
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