Keel Bulb

[Frank Russell]

Delfship is an excellent program that I find I am using over my old version 6 Maxsurf. But one of the features missing for me is in the “Keel and Rudder” menu. There is no option for “bulb”. It would be great if you also had the choice of circular or elliptical/flattened.

[Vic Bauwens]

hi,

A wizzard would of course be perfect, but meantime, modelling a bulb with proper naca sections is not very difficult.
Create a “keel” of some length, then delete everything but the root section. Copy-rotate this section (eg 60 degrees) along its long axis, then create new outer surfaces between the nodes of both sections. Delete the original section surfaces and rotate the newly created outer surface again till you have a 360 degrees surface, done.
This works equally well with different naca sections (of the same family) in horizontal and vertical plane, thus allowing to create a flattened/squashed/elliptical bulb with known hydrodynamic properties.

hope this helps…
grtz, vic

[Frank Russell]

Thanks for this it makes sense but i have managed to get as far as making a section but Copy-Rotate? Can’t figure that one out.

F

[Vic Bauwens]

Ok, maybe take some moments to go through the basic modelling techniques. Delftship bears resemblance to a lot of other generic modellers out there, but there are a few particularities yo have to get used to. one is that you can’t really select objects as such, it’s either control nodes, control edges, surfaces or layers. so to allow selection on object level, best to create each object in a separate layer.

let’s assume that you have indeed achieved the step where you have your bare naca-section in its own layer.
Now choose tab tools, then click the rotate button. Deselect all layers except the one that contains your Naca section.
select the axis along which you want to rotate (should be x if you started off with a keel) and set the angle, there is nothing more to it. Now you have two sections at a certain angle.
the slightly tricky part now is actually creating the external surface. its not difficult but some attention is required. like in other modelers, its best to maintain a clockwise rotation while selecting nodes for every surface. this will create consistent normals on the surface.
go back to ‘Home’ and enable the control net. zoom in till you have good view over all the individual nodes that make up your two sections.
select 2 pairs of nodes (one pair on each section) and click the button ‘New surface’. repeat this step till both sections are joined over their complete length.
then continue as explained earlier.

grtz vic

[giorgio zuppin]

Something is missing…
I found vicbauwens missing reply on the topic, and aligned with my own experiences.
So there’s some reason we do not know?
A perplex Jurgen.

[Vic Bauwens]

Hi,
what I meant by copy, is actually create a second keel which you strip again to the root section and then rotate that second section and continue with the rest.
sorry for the confusion, ….
grtz vic

best rgds, vic

[giorgio zuppin]

Do not mind, my fault, I’ve read maybe an unhedited reply…
Anyway, I like your approach, that’s what I mean with exploiting all features of a program.
Bye, Jurgen.

[Frank Russell]

Yes it is a little confusing and time consuming but it does work. I am also going to try turning the default hull into a torpedo bulb as well.

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