[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PSUBS-MAILIST] Wet-sub propulsion stability and X-tail
Hello Everyone,
I have been an avid reader of the psubs website for quite sometime. My
purpose in this email is two fold. First, I have decided to join the mailing
list, and I thought I would make my formal introduction. I currently a
college student and I have been interested in submersibles since my senior
year of High School. I undertook an ambitious project to build a one-man wet
submersible. Using trolling motors, batteries, plywood and PVC, I created
what many considered a death trap, but it worked! Due to problems with
electrical insulation, the system only performed admirably in fresh water,
going 5 or 6 knots. I vowed, that if I ever had the time, money, and
inclination, that I would go back and try building another wet sub,
correcting all the problems with the first design.
My second purpose in this email is to ask a few questions. I have done my
best to go back and read all the topics applicable to my situation. I found
very little information however, on my specific questions. I think the best
thing to do would be to give everyone a little background into my new
project, in hopes of giving you a picture of my ideas. I am majoring in
engineering, and I have experience in CAD. So someday I can attach some
design pictures.
I case you haven?t figured out by this point, I have decided to make a new
submersible. I was comforted to know I was not alone in my efforts. Most
people couldn?t believe I made my first sub, so I thought they would not be
surprised when I started another. I was wrong (It is difficult sometimes
when everyone thinks you?re completely nuts).
I have made every effort in my new sub to follow hydrodynamics. As I
mentioned before my sub is a wet sub, it will hold two people. The sub
design is 14? long and 4? diameter at the widest point, which is 5?6? down
the length. The sub follows a tear drop contour and is as hydro-dynamically
sound as I can make it and still keep the project manageable.
I wanted to make my project unique, and so I decided to try to come up with
one solution to the age old question of sub endurance and speed. Because my
vehicle is a wet sub, the driver must wear SCUBA gear to operate it.
Therefore it is not practical to drive the vehicle out to the dive site. I
wanted a way to quickly get the sub to the dive site, dive down, surface,
and then quickly drive the vehicle home. As I am sure you all know the ideal
hydrodynamic shape underwater performs very poorly on the surface. As waves
pile up on the hull, the vehicle looses all efficiency. I asked myself how
to fix this many times, and the solution seemed to be staring me in the
face. One of the advantages that wet subs have is their weight. I can make
my hull out of fiberglass. What would happen if I added enough power to the
vehicle to get the whole hull to hydroplane out of the water? The way the
sub is contoured it might work.
I have designed my sub to (hopefully) hold a 40HP e-start outboard motor.
When the sub is on the surface, the outboard will propel the entire sub out
of the water at a high rate of speed. I can drain the hull and close it
making it a surface boat. Underwater I will withdraw the outboard into the
hull and store it in a pressure compensated compartment. This minimizes
flooding issues with the motor, and eliminates the hull protrusion.
When I was faced with the obstacle of how I would steer my submersible, I
immediately drawn to the cruciform arrangement. I am a big proponent of the
KISS principle. Underwater steering can be accomplished with the cruciform,
but when the sub is hydroplaning the tail presents a problem. Even if I
extend the tail through some means so that a section of the rudder is
underwater, when the boat travels at high speed there could be a real
instability. Realistically the hull could be completely out of the water. I
was originally only going to have the motor stationary, but even if I rigged
it to turn a little, is there a danger of the sub getting out of control? I
have seen too many movies of those high speed boats flipping out of control
and hurting people. I know I am inside the sub, but it can still hurt me it
flips at 30+ mph.
I decided a way I might combat this instability it to use an X-tail. Some
navies around the world have opted for the tail because it gives 25% tighter
turns. I like it because I am considering using a piston to extend the lower
fins of the X into the water when the sub is at high speed, effectively
giving me 3 points of a stable tripod. Does this idea sound crazy? I could
turn the sub, but also adjust the hull pitch up and down.
My last question is if anyone has experience dealing with X tail control
systems. Due to the complexity, I would need all four fins to be actuated
separately. I would need joystick control, and some sort of motor control
that could take my stick position and turn it into the proper fin position.
The trick is the forces off the fins are additive, so all four fins need to
work together.
I realize this is a long email, but I look forward to reading anyone?s
insights on the matter.
Best Regards,
Jonathan Huntoon
_________________________________________________________________
MSN Toolbar provides one-click access to Hotmail from any Web page ? FREE
download! http://toolbar.msn.click-url.com/go/onm00200413ave/direct/01/
************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003. Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.
If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
removeme-personal_submersibles@psubs.org
Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of receipt
of your request.
mailto:removeme-personal_submersibles@psubs.org
PSUBS.ORG
PO Box 311
Weare, NH 03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************