Why no aerodynamic control/stabilizer surfaces on high speed cats?

What is the reason? Because cats are going fast enough to ******* blowover. THAT'S THE REASON. The same airspeed that makes blowovers possible also makes aerodynamic stabilizer and control surfaces effective. Maybe their driver capsules and escape hatches wouldn't get such a workout if the boats weren't blowing over in the first place.

 

My purpose was to aid in definition of the problem in an attempt to help with possible solutions. Sounds like you have your own solutions already, so have at it yourself. Why are you asking if you already know the answer?

 

The question

My question wasn't "What is the solution?"

My question was "Why aren't boat designers adopting the solution?"

Maybe the answer to that question is "Marine architects who can't figure out planing hulls are submerged in AIR not in water."

 

Alrighty. You are correct. Naval/marine architects are all stupider than you are. So figure it out yourself then wiz kid.

 

"War Whoop" already did.

War Whoop
Senior Member Join Date: Jun 2003
Rep: 23 Posts: 184
Location: Sunny Ft Lauderdale Fla

"I had cockpit-controlled canards on my offshore race cat’s years ago, Aside from the aerodynamic trim abilities thinking was to give the crew half a chance at control should the boat ever become airborne."

 

Then you're all set.

 

Not sure Arfons is a good example.... Craig Arfons died in the Rain X Record Challenger when it went airborne and disintegrated at about 270 mph.

I agree some of the responses above have missed your point and dealt with much larger displacement and slower speeds than you are considering. However, use of terms like "*******" and "dumbs h i t Sherlock" tend to create an image of you as an immature jerk, not worthy of being taken seriously. You might consider simply telling the poster that you are thinking in terms of speeds well over 100 mph, and he/she is off topic. Then it's his/her responsibility to address your specifics or opt out.

Getting back to your topic, I'm not sure there is much to be gained by adjustable control surfaces in the airstream at speeds in the 125-200 mph range. The existing adjustable control surfaces, i.e. drive thrust angle and control tabs, are hydrodynamic and work pretty well on even the fastest boats. The designers of power cats operating in this speed range all design the center of the hull as an airfoil, with the goal of finding the best compromise between enough lift to add speed, and not so much as to actually fly the hull. The main factor in regulating angle of attack in this speed range, again, is the hydrodynamic effect of the drive thrust angle and/or control tabs. I believe aerodynamic controls aren't used because their effect is negligible at those speeds.

At some point above 200 mph, It seems apparent that aerodynamic forces become an equal, if not more important, factor. Ken Warby added the T tail from a Cessna 172 to his record-setter, and he has a T tail on his new one, as do his hopeful competitors, so I think the importance of both vertical and horizontal aerodynamic controls might be a given ... at those very high speeds.

As for high speed sailing cats, I've seen numerous designs that are pretty far out of the traditional box. Most think of the mast and sail as an integrated, adjustable airfoil. That doesn't mean necessarily that they haven't thought of adding other control surfaces. It might mean they tried them and found that the sail/mast airfoil is much more effective. I honestly don't know the answer to that last, but there are many websites with info on cutting edge high speed sail cats.

BTY, is this theoretical, or are you working on a specific project?

 

200 mph speeds

Those links were to Art Arfons' boat, not Craig's.

Adjusting trim on fast cats is very effective for maneuvers that require planting the boat harder on the water (such as turns), but not of much help once the boat gets light.

Craig's boat didn't disentegrate. It broke in half just aft of the air inlets.

http://www.boatdesign.net/forums/showthread.php?t=15459

As best I could determine from having been an eyewitness, watching the video of the last run, and talking with friends of Craig Arfons this is what happened.

Craig's boat weighed 2,500 lbs and with the J-85 engine could develop about 5,000 lbs thrust on afterburner. The afterburner was installed only after initial trial runs revealed dry thrust would not be enough to break the record.

The major problem with Craig's boat was it would get up to a certain speed and veer off to the driver's right because it stopped responding to the rudder. For the record attempt they positioned the boat all the way to the left side of the course with the hope that by the time it got to the end of the kilo it would still be inside the course markers. Because of this problem the boat accelerated for a longer distance than it would have otherwise. About halfway through the kilo Craig gets worried he's going so far off course he's going to run out of lake so chops the engine. The sudden change in the loading on the sponsons sets off an episode of chinewalking, Craig releases the drag chute but it fails to inflate, and the boat does divergent enough to blowover.

The boat's Kevlar/fiberglass foamcore composite construction probably accounted for the boat being recovered in just two large pieces. The front half was intact except for a missing windscreen which I was later told had been punched out by a battery breaking loose from the control console. Craig was still alive when pulled from the cockpit and might have survived if one of the anchors for his restraint harness had not failed.

Whether a rudder and stabilizer fin arrangement like Bluebird's would've helped Craig's boat I don't know, but I was struck by the difference when I saw the photos of Bluebird's stern after its recovery.

At the moment this is all just an interesting discussion of theory.

 

You have a good point. Racing power cats have begun to encounter some of the aerodynamic situations facing unlimited hydroplanes, as they enter the region in which aerodynamic forces begin to exert a measurable effect. Personally, I believe there is a lot similarity between cats and sponson-type hydroplanes at higher speeds, since they both ride on just two small surfaces forward and one or 2 aft. As the ratio of wetted surface to airfoil surface decreases, i.e. as the boat gets "lighter", aerodynamics plays a larger role. Of course, what makes racing boats unique is that they operate simultaneously in two media with a huge difference between their densities. Too much influence by water = drag = slow. Too much influence by air = flying. The wrong kind of influence by either = loss of stability. One approach encourages bubble formation, in effect mixing air and water to create a medium that bridges the gap in densities, reducing drag and enabling higher speeds without flying. Most cat tunnels make use of this effect, and there are experimental underwater vehicles using supercavitation to create a similar effect, claiming speeds approaching 100 mph fully submerged.

War Whoop mentioned adding control surfaces to try to gain some control once the boat goes airborne, or try to prevent that from happening. I agree that this is an area for study that may increase safety. Any solution would likely require computerized control, since many launches are caused by hydrodynamic forces, usually a "rogue" wave, either natural or the result of wake convergence. The majority of launches followed by crashes seem to result from either chine/sponson walking (lateral loss of stability) or submarining , hitting the water bow first or stern first at too steep an angle (longitudinal loss of stability). Once the boat transitions to fully aerodynamic flight, it's probably too late to save it. The solution may lie in automatic controls, linked to motion sensors, fast enough to dampen or cancel the destabilizing force (usually hydrodynamic) and prevent the launch.

It's a fruitful area for creative thinking.

 

I think for offshore racing a boat that can run lighter in the water but still recover if it goes divergent will be the one with the best lap times. And for some of these functions some form of automatic control over the aerodynamic surfaces will probably be needed.

 

Whenever a boat (or notoriously, the 1999 lightweight Mercedes CLR Le Mans car) becomes airborne, it looses thrust and stalls, even completing a 360. I cannot see how a human would have the reflexes to cope with making a safe landing in such a situation. Windshear and microbursts etc., brought down significant numbers of aircraft, which were at least manufactured to succeed in air, the element for which they were designed.

Since 1995, the number of major civil aircraft accidents caused by wind shear has dropped to approximately one every ten years, due to the mandated on-board detection as well as the addition of Doppler radar units on the ground.

http://en.wikipedia.org/wiki/Wind_shear#Impact_on_passenger_aircraft

Lift off is instantaneous and without warning, either for cars or boats.

http://uk.youtube.com/watch?v=S-_-8iwSLo4&feature=related

"I think for offshore racing a boat that can run lighter in the water but still recover if it goes divergent will be the one with the best lap times. And for some of these functions some form of automatic control over the aerodynamic surfaces will probably be needed."

RF, surprisingly you haven't considered an injection seat. If you make the boat lighter, it'll lift off more often, becoming a self fulfilling prophecy. Unless thrust is continuous, any boat, car or airplane will gravitate remorselessly downwards. Basic aeronautics would inform you of these facts. What a pity this is not a boat. Good suggestion from Kach22i.

http://en.wikipedia.org/wiki/F2Y_Sea_Dart

Gentlemen, I expect we shall have a vituperative backlash from RF with heavy use of "*****" and other retorts. That is, if his previous form in other posts, wins through. Which of course, is unfortunate, because if he were able to resist antagonising many of our fellow travellers here, I suspect his ideas would not receive such short shrift.

http://www.boatdesign.net/forums/showthread.php?t=21261

OTOH, leopards do not change their spots and perhaps, RF will have to remain a prophet without honour in his own country.

Such is life, eh?

Pericles

 

It speaks for itself

Pericles was the Athenian king who started that disasterous war with Sparta. This probably says all we need to know.

That, or the fact you can't tell the difference between "injection" and E J E C T I O N.

Oops, almost forgot the fact you have no knowledge whatsoever of boat racing. If you did, you would already know a wide variety of racing boats are trimmed to run down the straights as light as possible since the less boat in the water the faster it goes.

Oh, then there's also the fact you don't know anything about aeronautics either. Pilots were making 120 mph landings in the Sea Dart seaplane fighter fifty years ago.

P.S. This is a message board not a cell phone. Any ***** knows there's plenty of room to use actual words.

 

I had adjustable control surfaces on my cats 15 years ago; they will work just fine if the designer has even a microgram of brain matter.

 

As was predicted, Frank the Rat, the most self opinionated blowhard yet to post here, has prematurely self ejaculated all over himself (and his keyboard no doubt) in his haste to punch his garbage into his computer and confirm what he is. An impotent sad old duffer who, to date, has not made public, any evidence of his manifold talents and frankly Frankie, I'm not surprised! With a name like yours, I believe your mother threw away the baby and raised the placenta as a child. Then when she got her first clear look at you, she decided to leave you on the front steps of a police station while she turned herself in.

Kach22i asked him if the following notes related to him? I have to include the questions and Frank the Rat's answer.

Originally Posted by kach22i View Post http://boatdesign.net/forums/showthread.php?p=122978#post122978
Which one are you?

FRANKLIN N RATLIFF Born Apr 1968 More Information on FRANKLIN N RATLIFF
9006 133RD RD Map It Recorded: 03/01/2005 FRANKLIN N RATLIFF business listings Check Yellow Pages
LIVE OAK, FL 32060 County (386) 364-1822 Leave a message for FRANKLIN N RATLIFF


FRANKLIN R RATLIFF Born Nov 1955 More Information on FRANKLIN R RATLIFF
5090 HOPERITA ST Map It Recorded: 11/19/2003 FRANKLIN R RATLIFF business listings Check Yellow Pages
ORLANDO, FL 32812 County (407) 380-6996 Leave a message for FRANKLIN R RATLIFF


FRANKLIN R RATLIFF Born Nov 1955 More Information on FRANKLIN R RATLIFF
6955 POMPEII RD Map It Recorded: Unknown FRANKLIN R RATLIFF business listings Check Yellow Pages
ORLANDO, FL 32822 County Leave a message for FRANKLIN R RATLIFF

FRANKLIN D RATLIFF More Information on FRANKLIN D RATLIFF
2169 US 27 HWY Map It Recorded: Unknown FRANKLIN D RATLIFF business listings Check Yellow Pages
PERRY, FL 32347 County Leave a message for FRANKLIN D RATLIFF

I'll be in Florida in a couple of weeks if you want to follow up on this *******.

http://forums.hotrod.com/ubbthreads/...1&fpart=1&vc=1


Is this you?

PROPSTERGUY@aol.com

http://dragracingunderground.com/dru...ic.php?pid=599

http://www.draglist.com/stories/SOD%...SOD-121201.htm

http://www.sonicwind.com/

Frankie' response:

It is not for me to presume that an individual's critical thinking skills have become so atrophied the concept of asking questions before making conclusions is entirely alien to them. It is not for me, as a result of their making unfounded assumptions because of their inability to ask questions, to apologize for not giving them a good enough explanation. It is not for me to assume that someone, despite their complete ignorance of the fact hydroplanes aren't the only boats light and fast enough for aerodynamics to be a strong influence, will not only still blather on as if I'm the one who didn't know what I was talking about but be so childish as to blame me for THEIR unfounded assumptions.

Would someone, anyone, care to explain what is meant here?. Not you Frankie, you've had your chance.

Here are a couple of other Uriah Heep efforts.


Drag Racing Story of the Day!

Fire Protection and Cockpit Intrusion
(Letters to Dick Wells)

By Franklin Ratliff

Dick Wells is 25% of the Board of Directors of the NHRA.

The following e-mails relate to concepts I first publicly proposed during my interview with Bret Kepner, published in the October 1999 issue of Drag Racing USA, and which I've continued to promote in on-line forums such as Nitronic Research and Drag Racing Underground. FR

October 19th, 2001

Dear Mr. Wells,

As I pointed out in my September 5th letter (below), there is no good reason for drivers of fuel cars ever to be seriously burned again, even on tracks that don't have a safety crew the caliber of the NHRA Safety Safari.

To address cockpit intrusion problems in dragsters, I suggest double-frame construction for the cockpit portion of the frame. The exterior frame could use arched instead of flat frame members with the exterior frame mounted to the interior frame through chromemoly plate diaphragms to spread the load. The use of double-frame construction would also simplify the creation of fully enclosed driver capsules for Top Fuel cars since the space between the interior and exterior frames could be filled with insulation. I suggest making the transparent portion of the canopy as small as practical, perhaps using double-glazing with tempered Pyrex glass for the outside and quarter-inch polycarbonate for the inside.

To solve some of the driver egress problems associated with installing a fully enclosed driver capsule in a Funny Car, an opening could be left in the body. The capsule could be built to match the contour of the body so that the capsule actually serves as part of the body. Several months ago Brent Fanning of Udder Nonsense Racing pointed out to me that even in existing Funny Cars because the cockpit is relatively well sealed, ram air can be used to pressurize the cockpit and keep smoke out while the car is in motion.

Sincerely,

Franklin Ratliff
------------------

September 5th, 2001

Dear Mr. Wells,

Below is why over two years ago I first proposed the concept of an X-15 style fireproof capsule that even in a fully engulfed car would keep the driver insulated from the fire inside a breathable atmosphere.

"...As near as I can tell he went up in flames in his funny car just before the finish line, steered toward the wall, crossed over to the other side, hit the wall, went airborne and then came to rest just before the turnout. The Sheriff's crew chief Scott Mason was down at that end just after the Sheriff's run and was the first on the scene. It took several minutes to get the body lifted and when they got in there, Keith's face shield was melted to his helmet. Scott pried one side up about two inches to try to get him some air. About that time, the safety crew showed up and tried to put out the fire. They had to cut the cage off so they could get Keith's helmet off..."

With regards to cockpit intrusion by another vehicle, there is a highly informative article on canopy and safety cell design in the September issue of POWERBOAT magazine. Unlimited hydro builders have, more than in any other motorsport, taken the lead in anticipating cockpit intrusion. With vehicles that can slice and dice a driver three different ways (propeller, rudder, AND skid fin) they have had some extra incentive.

Sincerely,

Franklin Ratliff
PROPSTERGUY@aol.com


Did you get any replies Uriah? (In the end all the evil machinations of Uriah Heep were frustrated by my old friend Mr. Micawber)

How about this trite verbal diarrhoea claim from the bottom of http://www.sonicwind.com/?

"Also, the most enlightened Land Speed Record expert on the planet, Franklin Ratliff, contact him at Propsterguy@aol.com"

Finally, we get Frankie babe's scribbles to Hot Rod magazine, where once again his self esteem is trampled into to dust by other members.

http://dragracingunderground.com/druforum/viewtopic.php?pid=599

Fwankie, there's a chip on your shoulder so crepuscular, that nobody will bother to urinate on you, even if you were on fire in a gutter.

You should now be aware nobody as calculatedly rude as the British, which naturally amazes Americans, who do not understand the studied insult and can only offer abuse as a poor substitute. When the debate is lost, slander becomes the tool of the loser. You a now a disinterest of mine, as your works consigned are consigned to oblivion.

Pericles

 

All you've proven is <removed> who doesn't have the mental wherewithal to respond in any kind of thoughtful or constructive way when your ego is threatened, but you're <removed> you have no clue that engaging in personal attacks like this only proves everyone else's perceptions of you as a complete whackjob.