Like Tree0Likes

rear wings on boats

Reply
Old 07-21-2005, 10:57 AM
  #31
Registered
 
dreamer's Avatar
 
Join Date: Mar 2002
Location: cleveland
My Boats: boatless... with money in the bank!!
Posts: 5,798
Default Re: rear wings on boats

Quote:
Originally Posted by _vonb
I don't doubt it at all. But a wing is all about downforce and is in fact an "anti-aerodynamic" device.

Aerodynamics refers to punching a hole through the air with minimal resistance.

The kind of wings we're discussing here are devices that, in principle, try to keep you connected to the surface.

from nasa

aerodynamics

The science that deals with the motion of air and other gaseous fluids and the forces acting on objects as a result of the relative motion between the air and the object
dreamer is offline  
Reply With Quote
Old 07-21-2005, 11:04 AM
  #32
Registered
 
Join Date: Jan 2001
Location: ST. Louis, MO, USA
Posts: 1,658
Default Re: rear wings on boats

While we're on the subject. I've always wondered why cat makers have not added an adjustable wing between the front of the sponsons. With speeds in excess of 100mph, it would seem to be an effective way to control trim.
Anyone know of any attempts at this?
Gary
Gary Anderson is offline  
Reply With Quote
Old 07-21-2005, 11:40 AM
  #33
Registered
 
dreamer's Avatar
 
Join Date: Mar 2002
Location: cleveland
My Boats: boatless... with money in the bank!!
Posts: 5,798
Default Re: rear wings on boats

Quote:
Originally Posted by Gary Anderson
While we're on the subject. I've always wondered why cat makers have not added an adjustable wing between the front of the sponsons. With speeds in excess of 100mph, it would seem to be an effective way to control trim.
Anyone know of any attempts at this?
Gary

some use a tunnel tab at the rear
dreamer is offline  
Reply With Quote
Old 07-21-2005, 11:42 AM
  #34
Registered
 
Join Date: May 2002
Location: MIAMI, FL
My Boats: 4 BOATS KILLED :)
Posts: 1,262
Default Re: rear wings on boats

Formula, Betty Cook and John Connor built a pretty advanced composite 38' cat in the 80's. It had a had a non-slotted nose flap that extended down and forward like a dc9. Didn't work. On a dc9, it modifies the wing shape, makes it larger and gives more lift and drag. On the boat, it only stopped up the tunnel and slowed it down.
BROWNIE is offline  
Reply With Quote
Old 07-21-2005, 11:44 AM
  #35
Registered
 
GregP's Avatar
 
Join Date: Apr 2001
Location: Annapolis MD
My Boats: 1989 Scorpion 32 CC
Posts: 1,464
Default Re: rear wings on boats

Quote:
Originally Posted by Gary Anderson
While we're on the subject. I've always wondered why cat makers have not added an adjustable wing between the front of the sponsons. With speeds in excess of 100mph, it would seem to be an effective way to control trim.
Anyone know of any attempts at this?
Gary
Yep. A friend did some design consulting for the unlimited hydro boys on adjustable front wings between the sponsons to kill the lift at take-off and try to help prevent blow overs. I don't remember which team. Trick I think was no one could dedicate enough attention to how the boat was flying to be able to kick the wing fast enough if it started to get away.

-Greg
GregP is offline  
Reply With Quote
Old 07-21-2005, 11:47 AM
  #36
A to Z
Platinum Member
 
Sean H's Avatar
 
Join Date: Apr 2004
Location: KC/LOTO
Posts: 9,156
Default Re: rear wings on boats

Quote:
Originally Posted by GregP
Yep. A friend did some design consulting for the unlimited hydro boys on adjustable front wings between the sponsons to kill the lift at take-off and try to help prevent blow overs. I don't remember which team. Trick I think was no one could dedicate enough attention to how the boat was flying to be able to kick the wing fast enough if it started to get away.

-Greg

you would spend all your time trying to adjust the angle of attack on that wing and unable to throttle or drive, the main problem with adj wings on boats is that boats never have the same attitude... they are always pitching and rolling, just like a tunnel tab that is used incorrectly, a front wing like that could be deadly in a high speed cat...
Sean H is offline  
Reply With Quote
Old 07-21-2005, 11:50 AM
  #37
Registered
 
GregP's Avatar
 
Join Date: Apr 2001
Location: Annapolis MD
My Boats: 1989 Scorpion 32 CC
Posts: 1,464
Default Re: rear wings on boats

Quote:
Originally Posted by BROWNIE
Formula, Betty Cook and John Connor built a pretty advanced composite 38' cat in the 80's. It had a had a non-slotted nose flap that extended down and forward like a dc9. Didn't work. On a dc9, it modifies the wing shape, makes it larger and gives more lift and drag. On the boat, it only stopped up the tunnel and slowed it down.

The water surface for a cat acts just like the ground on formula cars, and creates a much different set of aero than a wing in nice free space on an airplane (it's also a much more complicated analytic model). Rolling tires are even harder to model correctly.

The height/spacing is very critical, on formula cars a 1/4" or less change makes a big difference. On a cat running height over the waves is continuously varying, making it nearly impossible to optimize as a single solution. In "very" general terms the height of the gap as a function of the wing/tunnel length as a % is what drives the effects, so on a 40' cat the senestivity is less, but still a few inches matters.

-Greg
GregP is offline  
Reply With Quote
Old 07-21-2005, 11:50 AM
  #38
Registered
 
Join Date: May 2004
Location: Stuart
My Boats: WCM
Posts: 254
Default Re: rear wings on boats

Randy Scism built a victoryTeam cat in the early nineties, with a big stabilizer wing on the back and also an adjustable front tunnel flap. I can't seem to find photos of it.
They called it the bat boat. was weird looking, but fast.
It had a huge wreck with Polli and Curtis, who were in the BILBOA boat, I think it was in St. Tropez.
wcmarine is offline  
Reply With Quote
Old 07-21-2005, 12:41 PM
  #39
Registered
 
GregP's Avatar
 
Join Date: Apr 2001
Location: Annapolis MD
My Boats: 1989 Scorpion 32 CC
Posts: 1,464
Default Re: rear wings on boats

Wings produce lift (more accurately a normal force) and drag (axial force). If the camber/angle-of-attack is "up" it make lift ala an airpalne. If it is down it creates downforce ala race cars. If you put it vertically it creates side force (like in direct sideforce generators for advanced fighter aircraft). It's the same wing, same physics. Just point the force the direction that you want it.

Oh, and if you rotate it "just right" it produces thrust for a propeller or lift again for a helicopter rotor.

"Streamlining" is the coloqial term for minimumizing drag or disturbance to the airflow. Now days it's just called drag reduction.

I won't get into boundary layers and viscous -vs- induced drag as it's time for lunch.

-Greg

Last edited by GregP; 07-21-2005 at 12:43 PM.
GregP is offline  
Reply With Quote
Old 07-21-2005, 01:46 PM
  #40
Registered
 
dreamer's Avatar
 
Join Date: Mar 2002
Location: cleveland
My Boats: boatless... with money in the bank!!
Posts: 5,798
Default Re: rear wings on boats

http://www.grc.nasa.gov/WWW/K-12/Foi...l/fsim001m.htm
dreamer is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
pullmytrigger
General Boating Discussion
4
04-17-2003 08:13 AM
Playn
General Boating Discussion
21
06-14-2002 03:57 PM
powerqrudy
General Boating Discussion
1
03-09-2002 06:18 PM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 06:09 AM.


Copyright 2011 OffShoreOnly. All rights reserved.