Building the De Havilland DH-106 Comet 4

[scon10]

From data on the various Comet marks, I roughly calculated, that the wing of the BOAC Comet needed around three times the wing end part 55, that you designed. So I copied that specific part and using Paint Shop, I manouvered it on the outside of the original Part 55. Then I made another copy of Part 55, but including the tip itself, Part 56, and again paint-shopped it to fit the outside of the second copied Part 55. And so I now have an elongated wing, with a fitting wingtip. See picture.

I also included two scans of the Comet 3 and Comet 4, taken from "The first jetliner: The story of the De Havilland Comet" by Timothy Walker, Scoval Publishing Ltd, 2000.

Finally, some more pictures of the engine framework, and the wing planform, to give an impression of the scale. You will notice, I have included some additional brackets to better fix the fairing profiles B47 and B48.

[Don Boose]

This project is really moving along. Fine work!

Don

[Lex]

Nice progress so far and thanks for the info!!

[scon10]

Lex, I have a question on the construction of the exhausts, see the pics.
There is a part 50b, which looks like it needs to be doubled, so that the inside would be black, with the triangles for the noise supprssors on the inside.
However, then a white band remains and the inside will further show two white areas because of the larger length of that part as compared to the black area.
In the instructions you mentioned to insert part 50b "until this line". There is no line visible, but I am assuming you mean the line bordering the sharp ends of the triangles, correct?
So I am at a loss as to how you intended the exhausts to be constructed. Can you please clarify?

Thanks for your help.
Regards.

[scon10]

Just a remark to further improve this great model. The bulkheads of the engines only show marks for outboard and up. It is near impossible to position them correctly, with their asymmetrical shapes, in their respective barrels. It would be much easier, if there was a mark that pointed to the closing seam of each engine barrel, so the engines will get the appropriate form and better fit together. Could you therefore please mark the point of the seam on the engine bulkheads?
Thanks.
Can you also please indicate, how the exhausts should be constructed?
Thanks again.

[Lex]

Sorry for the late reply scon. About the exhaust:

The parts 50b and 50c are supposed to be folded in the middle, so that the black rectangles are glued to the back of the parts themselves. ALL the white bits are THEN cut away... Hope that explains it, I don't have a printout ready so can't take photos of the real thing...


And I will take the issue on the supports in to account in the next release. Cheers!

[scon10]

OK, thanks. The extending black part of 50B, carrying the white punch-out holes, has the circumference of the the aft part of the engines (parts 38 and 49), I'll by-pass some steps by cutting off the white area's beforehand, trimming the black doubler to the length of the circumference (plus about an additional millimeter to account for paper thickness) and glue it overlapping together, forming its own glue tab. I'll make some pictures tomorrow.
Meanwhile, I am now constructing the outer wingframes. If it's ok with you, I'll have some "in-service experience" of this process to show how I want to maintain a contineous strength element carrying tension and compression stresses, as a wing spar should do (I'm an aeronautical engineer, you see). I'll explain tomorrow with some pictures what I mean, and also I'll make some pictures to show how the completed right side engines look like. I think their shape is great!
Regards.

[Lex]

Thanks! As someone who loves aeronautics I'd love to know that! Also I'm having a laptop changeover these few days so might not have time to work on models, but everything should hopefully be over by the weekend...

[scon10]

Some progress reports on the wing construction. I decided I wanted to have a bit more contineous integrity in the sub-assembly of wing spars, ribs and central spacer, so I cut out only the bottom part of the ribs, which should fit inbetween the spars attached to the horizontal spacer. That means you have to cut out a slit the thickness of the cardboard stiffener that I am using, in the top of the spars halfway to the centerline, so that the ribs will slide in place. The bottom goes in last. I hope the pictures can make this clear. In order to be able to see the lines on the parts, I used the left parts for the right winghalf, so that the printed sides would face outward. That's why you see the crossed out letters L...

I had intended to extend the spars all the way through the engines and under the fuselage belly to connect to the other winghalf, but I was hasty and made the engines first, and then that opportunity was lost. Next time I'll try to think ahead .
However, it appears, that the doubling of the two parts B49 above and under B24 gave a stiff enough construction to attach the outside spacer and ribs to maintain correct dihedral ("v-position" of the wings when viewed from front), so I don't think there will be a problem of sagging wings in the future.

To close off, I included some pictures of how fuselage and engines look in their silvery finish. At the end, the finished will be varnished, which will take away the sharp edges a bit.
So long.

[Lex]

Very sorry for the late reply... The model is looking great! According what you have said there is much to improve on this design, I will learn from the words to make my next design better ^^ Meanwhile I anticipate more updates...! Please keep going ~~

Edit: Did you cut the voids for the wheel well on the wing supports? Or are you going to build the model without gears?