to all those brains out there-help!!!     i don't have time or
 money to waste on weak cad programs. i need a great cad program to
 design a twin rotary amphibian. i am a newbie at cad. (no habits to
 break) i will also be purchasing a dedicated laptop for the job.
 suggestions on brand? thanks george g. on the vote for rhino. does
 anyone else have experience they would like to share?

 --
 flyboy


 I like Rhino.

 Paul Lamar


 A lot depends on what you want to do.  In the CAD world there
are many
 flavors of programs, but they usually are categorized into either
 parametric
 and non-parametric.

 In very general terms, parametric programs allow the user to create
 designs
 where some dimensions are related others such that one can
change one
 dimension and have related dimensions automatically change.  For
 example,
 one might create a shaft with a bushing around it.  One could
 specify that
 the clearance between the shaft and bushing must always be a
 specific value.
 If you later elect to increase the size of the shaft, the
bushing will
 automatically increase in dimension so that the specified
clearance is
 maintained.  This is just one (simplified) example of parametric
 behavior.

 Non-parametric programs, do not respond as noted above.  If one
 wishes to
 increase the size of one part, the user is often required to
 manually redo
 the other parts.

 SolidWorks is one example of a popular parametric design program
 while Rhino
 3D is an example of a non-parametric program.  Each has its
respective  strengths and tradeoffs.

 In addition to this feature, some CAD programs permit designers to
 create
 very smooth, very complex surfaces while others are more limited
in this
 capability.  Arguably, Rhino 3D currently permits users to
create much
 "nicer" surfaces as opposed to SolidWorks.  In this context, one
 simplistic
 example of "nicer" refers to how smoothly one surface blends
into other
 surfaces.  Imagine sighting down a car's body.  "Nicer" surfaces
 will not
 display kinks and obvious transitions while less nice ones may have
 noticeable surface transitions.  This surfacing capability is
one of the
 reasons Rhino 3D has grown so popular among industrial designers,
 and others
 wishing to create smooth, nice looking shapes.  But don't
misunderstand;  SolidWorks creates nice surfaces, but Rhino 3D
does it better...at
 least for
 the moment.

 If one accepts, for the sake of argument, that Rhino 3D has a more
 powerful
 surfacing capability, as compared to SolidWorks, and one is more
 interested
 in form design, it might be a better choice than SolidWorks.  On the
 other
 hand, if one is designing mechanical assemblies with a great
number of
 anticipated dimensional changes, SolidWorks might be the program to
 choose.
 Of course there are other programs out there and other criteria to
 consider,
 and there are certainly other features to consider, even between
 Rhino 3D
 and SolidWorks.  One should also not forget popular programs like
 AutoCAD.

 More recently, McNeel (producers of Rhino 3D) have addressed this
 parmetric
 issue by providing a well behaved path such that nice looking,
 non-parametric shapes can be designed in Rhino 3D and then
imported into
 SolidWorks where the internal mechanical components of the user's
 design can
 better be designed to fit into the Rhino 3D shape.  Unfortunately,
 if the
 user later elects to change the size or layout of his mechanical
 assembly,
 such that it no longer fits inside the Rhino 3D shape, one has
to go
 back
 into Rhino 3D to resize the enclosing shape.

 Now, if cost is not a major issue, one can always use Catia from
 Dassault
 Systemes.  It is parametric and has very powerful surfacing
 capabilities.
 Catia is the standard for companies such as Lockheed and Boeing.
  But you
 had better think it over.  A single user commercial (retail)
version of
 Rhino 3D lists for $995.  A single user commercial version of
SolidWorks  lists for about $4,000.  And Catia goes out the door
for $10,000 to
 $14,000.


 Then there is the issue of ease of use or the learning curve.
  Clearly, the
 more features a program has, the steeper that curve may be for
 people new to
 CAD design programs.  Rhino 3D is alleged to have an easier learning
 curve
 as compared, say, to SolidWorks.  And some would argue that
Catia is
 even
 more difficult to learn.

 I happened to use SolidWorks for a lot of my mechanical designs, but
 I am
 also very familiar with Rhino 3D and often recommend it to those
more  interested in esthetics.  I know that Paul likes Rhino and feels
 that, up
 until now, it has satisfied all his needs.  But Rhino would not have
 permitted me to design the things I have, such as gearboxes for
turbine  engines and other mechanical assemblies.

 So, where does this all lead.  Personally, I would recommend
SolidWorks  unless you are primarily interested in producing
things with very
 complex
 surfaces.  Most amateur aircraft, however, do not involve such
 surfaces.  I
 know of one aircraft design being done by a close friend using
 SolidWorks
 which is outstanding.  I doubt that it could have been done in
Rhino 3D.
 There were many dimensional revisions which would have been
 exhausting to do
 in Rhino.

 I don't know much about AutoCAD, so I'm in no position to comment
 intelligently about it.  But I have used earlier versions of Catia
 and think
 that, for most amateur designers, it is overkill.

 I'm sure that Paul has other views and know he will be
responding to
 this
 message.  If he doesn't I'd be quite surprised.

 George Lazik
 Woodland Hills / Santa Paul California

 I designed this gear box in Rhino and had it made in the same NC
shop  George had his made :) I will say one thing about Rhino Ver
3. It
 doesn't  do variable radius fillets worth a damn. version 5 is out
 so I don't  know if they fixed this.

 Cowls in aircraft are very important because you must fit all the
 parts inside. Rhino does cowls much better than Solid Works.
 It is tricky to do cowls but I can help. It took me about
 a month to learn how to do them. Not 24/7 just off and on
 for a month.

 IMHO it is not worth $4000 for Solid Works.

 Paul Lamar


 Hi Paul

 I have SolidWorks and it's very good but the learning curve is
steep.
 If Flyboy only wants' to design an airplane what about Aerologic
link  attached.

 http://www.aerologic.com/index.html

 Might be worth a look?

 Clive      England


Flyboy, I don't reccommend trying to use a laptop on any of the
better CAD systems. The screen size is too small and you will
spend more
time resizing viewports than designing just to get things big
enough to
see what points you  are picking. The second consideration is
processingpower. The typical laptop is about 1.8 Ghz and dual core
with 2Gb of
ram. This will operate the program as long as your model is small and
not very detailed or finely meshed. Using a desktop allows adding a
graphics card such as the asus 9800 or nvidia 9500 which have in
excessof 120 processor cores.( For some reason the radeon based
Ati cards have
issues with CAD.) This shifts the on screen display processing to the
pci express-16  based graphics card for processing with a transfer
rateof 3 Gb/second. Anytime you zoom in or out the active viewport
has to
regenerate. My current drawing is 230 mb which for the 4 viewports is
approaching 1 GB of display points.
   If you know where you are heading with a design and are using
more  of the editing type commands it doesn't take much to
overheat a
laptop. If you find yourself waiting for the command line to
display the
computer is maxed out during those times. If you use a laptop for
microsoft office or surfing the internet there is much more time
for it
to dissipae the heat.  I have problems with any desktop having power
supply failures. 500 watts is the minimum that will survive and
650 is
more reliable.While running CAD or gaming programs the power
supply is
at 350 to 400 watts output and that is a lot of heat to dissipate.
If
you run CAD on a laptop it will have to be plugged into the wall
to stay
on for more than 20 minutes just like a deshtop.
    The best deal on the computer would be a used gaming computer
from craigs list or e-bay which are often priced at what I spend on
just the ram to build one. One with an nvidia (not ATI) video card
and 4
GB of ram that is not running overclocked which can overheat the
northside bridge, the processor, and the video card.

george grimes

George, I'm going to have to disagree w/ you on this one.
I'm using a Dell M6300 Precision laptop w/ a 17" screen and
4Gb of ram.  It has a Nvidia Fx1600M graphics card.  I've
been running Solidworks on it in 32bit for several years
and it rivals a 8 processor 4GB machine I have at work.
It's not got as much screen area as a desktop [my work PC
has two 24" units] but when I'm home I can also hook it up
to my PC screen and get a larger screen if I so choose, but
I rarely have the need.

The Precision  series laptops are certified to run
SolidWorks and do it very well.

I've actually got parts on order for an upgrade this laptop
now that it's off warrentee.  In the next month it will
move to a 8GB 64b system running Win7 w/ a 1TB harddrive.
[or a 640GB if the price doesn't come down some..  the HD
price has been what has been holding me off upgrading for
the last few months].

Laptops have come a long way in regards to processing
power..  I use mine on an AC supply when I'm at home but
have been known to watch vid's while flying and it lasts
for several hrs [2.75 or so IIRC] while playing video or
doing mild CAD work.


Love my Precision laptop!!!

Btw on the subject of Surfacing and SolidWorks. I think the
program got a bad rep for this in the past when it was a
bit weak.  In recent years they have been adding
functionality to the surfacing side of things and the
impact has been huge!  I know this as been mentioned as a
concern, but I fail to see it applying to the current
versions of the software.  Not only that but if you wish,
you can add formula's to curves and equations to sketch's
to drive geometry.  One of the model's I did [I've posted
pic's in the past] has over 85 Equations in it, driving the
fuselage shape..  by simply sliding two independant splines
it can change the cross sectional shape along the fuse's
length..  a fairly handy feature to assist in 'tweaking'
the shape to be pleasing to the eye..

It isn't cheap, but then it's usually the case in life,
the good stuff never is.. :)

Fwiw

Jarrett Johnson