It’s taken a little longer than I had hoped but the first working version is DONE! Yes you read right I am proud to announce the first public version of the Gertler Series 58 Profile Generator. You can render different profiles based on the parameters and copy the points into your Clipboard. It’s completely working, requires you to have Java installed. Since I developed against Java 1.6 I would suggest that you also install it on your Computer you can give it a shot with earlier versions but I wont test it against those. If you test it and it works let me know.

So click on the link to download the Preview:

Airshipworld Profile Generator Version 0.5

(AirshipworldProfileGenerator-05.jar) 15,7KB

Once you have downloaded the jar and have installed Java properly you should be able to start the generator by simply double clicking on the Jar file. Or you open it via commandline by entering the command “java -jar AirshipworldProfileGenerator-05.jar”. Both should work but let me know if there are problems. Use the comments of this post to share your thoughts. Also let me know what features you are missing, any bugs you find, wishes you have. This application will be going open-source once we reach version 1.0 until then I will post updates here on the Blog so make sure to subscribe to get the latest updates.

Andreas, great!

I had a little problem running the jar file, since windows made it a

zip- file when I downloaded it. So I changed the extension manually

from ‘.zip’ to ‘.jar’ and then it worked.

One point: The parameter ‘L2D’ should read ‘Length to Diameter Ratio’

or better ‘Slenderness Ratio’, while it’s now ‘dimensionless bow

radius’ due to a copy paste mishap I guess.

I think it’s a most valuable tool :o)

Best, Johannes

PS.: There’s a typo in ‘Getler Series 58 Generator Preview ‘

Hello Johannes,

yes you are right, I corrected it already and it will be in the next version.

Also Corrected the typo.

Thanks for the feedback.

Andreas

Hello Andreas,

finally a useful tool in the internet!

Thank you guys. Download with Vista was no problem. Exept, when started and I switch windows, it closes again.

greetings

Philip

Hi Andreas,

thanks again for implementing the tool in java and bringing it to the public. I think the Gertler Series 58 is a big deal, comparable to the NACA four and five digit profile sections.

Let me suggest further improvements for the tool, not wanting to be pushy, just if you agree.

– polynomial coefficients

It would be nice to have the polynomial coefficients a1 to a6 as output too. The format should include 10 significant digits.

– CB

The centre of buoyancy or centre of volume, should be computable (if I did my homework correct) by

(a1/3+a2/4+a3/5+a4/6+a5/7+a6/8)/(a1/2+a2/3+a3/4+a4/5+a5/6+a6/7)

– Cs

A surface area coefficient is a little more challenging. Analytically this might be fun for mathemaniacs, but I’d rather prefere either a numerical or a statistical approximation. WRT the next point, CG, it should be done numerically.

Since the point coordinates x and r are already computed, we can compute the distance between the points ds by

ds=sqrt(dx^2+dr^2)

where

dx(i)=x(i+1)-x(i) and

dr=r(i+1)-r(i)

with i from 1 to n-1, n being the number of points.

Then we need the mean radius rm between x(i) and x(i+1) with

rm(i)=r(i)+dr(i)/2

The surface of a slice between x(i) and x(i+1) is then approximately

dS=pi*rm^2*ds

The surface area S should then be

S=sum(dS(i)) for i=1 to n-1

where n is the number of points.

There are several approaches around to build a surface area coefficient. I’d propose to use, at least in this context, the Gertler variant with

Cs = S/(L*pi*D)

Here, the referencs is the surface of a cylinder of the same length and diameter. Obviously, L is 1 here and D is L2D.

– CG: The centre of gravity of the surface

This is the ratio of the moments of dS times xm and the surface area S with

CG=sum(dS(i)*xm(i))/S for i=1 to n-1

where

xm(i)=x(i)+dx(i)/2

– Clipboard format

How about a TAB as delimiting chacacter between x and r? With OpenOffice CALC a semicolon is not a problem, but a TAB would facilitate the import to MS EXCEL via clipboard.

– n

Would be great, if the number of points could be chosen by the user.

Later we could even add approximations for added masses and the destabilising Munk moment, but this is a different story :o)

Again, thanks a lot, and dont feel pushed. These are just suggestions.

Best, Johannes

PS.: Try as input the following:

m = 0.5

r0 = 0.5

rl = 0.5

Cp = 0.667

L/D = 1

;o)

oops, there is a typo in my last email:

“The surface of a slice between x(i) and x(i+1) is then approximately”

[WRONG:] dS=pi*rm^2*ds

[RIGHT: ] dS=pi*rm*2*ds

Sorry.

Best, Johannes

OK, so finally someone rightly points out that theres a need for a pc program for airship dreamers and designers. Fine. Now howsbout starting off by :

1. Clearly establishing the needed elements in the software workspace in a logical manner (a list, maybe).

2. Initially designing the software workspace simiar to a common photo-editing or program (to make it easier to learn).

3. Using tiny picture icons grouped cose together, and avoid too many GD menus and sub-menus.

4. Providing lots of basic shape templates; lets not have to re-invent all this stuff.

5. Provide lots of automated functions, like before and after dual views, etc.

6. Always have UNDO (to 30x at least) as a toolbar command, not a command from a GD dropdown menu.

7. Windows and dialog boxes need to always have last-position memory as the default (somebody at Corel and Ulead needs a few shouts bout this).

8. Make it affordable for others to use !

Now a word about dual-envelope designs. I hope it is now evident to most (if not all) that for multi-passenger airships this is superior to the long traditional and nearly obsolete single-envelope designs because it:

1. Provides greated structural rigidity.

2. Provides shorter lengths and heights, while having greater lift volume.

3. Provides for designs that can land on water(with passenger compartments at the sides).

But youre off to a good start. now howsbout adding to the above ?

Thats all for now. Any questions /comments ? – paul

> Now howsbout starting off by :

1. Well, go ahead then.

2. see 1.

3. There are no menues.

4. Actually this program is a tool to establish basic shapes.

5. see 1.

6. This program is a basic tool, not a toy for senselessly clicking around.

7. see 1.

8. Did you notice the “download the Preview” link?

I for my part would have even been happy with a command line interface. The way Andreas put the algorythms together and gave it to the public is just great in my honest oppinion, no bell and whistels needed.

Concerning double bubble envelopes:

1. For hogging and sagging loads, the section modulus of a flat section is lesser than for a round section of the same cross sectional area. So how could a flat envelope be more stiff than a round one?

2. Shorter height is an issue concerning hangar space.

For a given volume, length is a question of crossectional area and not of crossectional shape.

3. Why this? Zeppelins did “land” on water. Only problem being waves.

Regards, Johannes