RE: [PSUBS-MAILIST] Convention: OMSI USS Blueback tour and other questions

[Alec Smyth <Asmyth@changepoint.com>]

David,

The lobes are very easy to understand from a photo, but hard to explain in
words. Think of a park ranger hat which has 4 "dished in" depressions around
the crown of the head. That is one of the ways in which a cylinder might
fail. It might fail by dishing 4 times like the ranger's hat, but it could
also dish in 3 places, 5 places, etc. I'm afraid you just need to plug in
different values and see which one produces the lowest failure pressure.
After a few values you can spot the trend, so this is not as iterative as it
sounds.

Regarding the admittedly counter-intuitive result of decreasing yield
performance as you increase frame width and depth, I believe its because
what matters as far as the formulae go is the moment of inertia of the
frame-shell combination. It is possible some heavier geometries have worse
moment of inertia than lighter ones. It just depends on the specific
geometries. There is a tab with auxiliary functions, and the various moments
of inertia have columns on it. If you look at those, you should be able to
explain the effect for your given geometry. 

rgds,

Alec

-----Original Message-----
From: DAVID A HAVERBERG [mailto:carro@wans.net]
Sent: Saturday, February 23, 2002 10:59 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Convention: OMSI USS Blueback tour and
other questions


I'm using the PSub hull calculation spread sheet and have two questions.
What are Circumferential Lobes and why does the Shell Yeild decrease if in
increase the frame thickness and depth?
----- Original Message -----
From: "Alec Smyth" <Asmyth@changepoint.com>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, February 12, 2002 1:54 PM
Subject: RE: [PSUBS-MAILIST] Convention: OMSI USS Blueback tour and other
questions


> Ray, I'll definitely go to all of it, but I think the family would stay
> behind. Incidentally, is the website open for updates? If you need any
> support divers for the lake, please put my name down for that.
>
> Incidentally, when was it the site is open for updates again? I'm happy to
> say I've had some good progress on the project.
>
>
> thanks,
>
> - Alec
>
> -----Original Message-----
> From: Ray Keefer [mailto:Ray.Keefer@Sun.COM]
> Sent: Tuesday, February 12, 2002 3:56 PM
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] Convention: OMSI USS Blueback tour and other
> questions
>
>
> Hi,
>
> I called OMSI (Oregon Museum of Science and Industry
http://www.omsi.edu/ )
> regarding a tour of the USS Blueback. They have a techno tour they hold
the
> 1st Sunday of each month. The convention dates are:
>
> Friday, 16 August 2002 Regatta
> Saturday, 17 August 2002 Meeting/OMSI
>
> There is a possibility that OMSI would hold a special techno tour for us
> but certainly not on Saturday afternoon because it is too busy. Maybe
> Saturday morning and more likely Sunday morning. They want to know
numbers.
>
> The question is, how many of you are interested? I guessed at 15 but
> a guess is not worth spit. Actually I need to ask some questions to
> get a feel on the scope of the convention:
>
> 1. Who is coming? Your name and number in your party.
> 2. How many want to see the sub. Each person has to be over 36" tall and
>    and at least 3 years old.
> 3. How many are coming to OMSI?
> 4. How many are coming to the regatta?
> 5. How many are coming to the Meeting?
> 6. How many are bringing their own subs? Trailers?
>
> Regards,
> Ray
>