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Aero Dynamics in Drag Boat Racing
Last Post 08 Feb 2007 07:52 PM by Admin Sims. 14 Replies.
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Admin Sims aka "The Admin" Send Private Message Posts:3043 Admin Sims
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08 Feb 2007 07:52 PM

In the 90's feather weight hulls were thought to be the item, today it seems that the heaver hulls, set forth by Anderson/Patton/Meyers are the way to go quicker and faster.

 

Based from this picture from pro mod 115 of his Fineline pro mod airing it out and knowing how fuelers thought the same and pushed the limits of the single screw during this period of time, is it conclusive to say today…

 

Heavy Hot Pounding Fiberglass Twin Screw Nitro Drinking Fire Snorting Hydroplane are the way to  “git ur dun”? jumpin  


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images.jpg

 

Greg Padgett Send Private Message Posts:372 Greg Padgett
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08 Feb 2007 10:19 PM
I dont know the real answer. but my dad always said in a fuel boat heavier the better, his thought was the heavier you can make it the more load it will keep on the motor, the more load on the motor the more power and less chance of dropping a cyl.


NOTHING TURNS ME ON LIKE NITRO AND DIRTY STRIPPERS I LOVE THOSE STRIPPERS

CAPSULES WHO NEEDS THEM



NOTHING TURNS ME ON LIKE NITRO AND DIRTY STRIPPERS I LOVE THOSE STRIPPERS

CAPSULES WHO NEEDS THEM
Eddie Knox Send Private Message Posts:1044 Eddie Knox
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09 Feb 2007 12:36 AM
I think it's more like the ability to stay together at speed and rough water. Although I concur to a certain degree that the weight could help with loading the motor. This can also be achieved through gear/prop combinations. I do know this, the cars guy's spend hundreds of thousands of dollars to buy the absolute lightest things they can get their hands on. weight & mass x acceleration. Getting back to areo or aquadynamics. There is probably a lot more left on the table than we will ever figure out.
Problem Child TFH #712



www.eddieknoxracing.com
Problem Child TFH #712
Admin Sims aka "The Admin" Send Private Message Posts:3043 Admin Sims
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09 Feb 2007 02:00 AM
Eddie thanks for your input, aquadynamics... great pun on words!!!
 
Hopefully you will continue to figure it out and reclaim your ET record and even capture a MPH record in addition to a back to back championship!hop

boat in pool 2.bmp
boat in pool 2.bmp

 

Eddie Knox Send Private Message Posts:1044 Eddie Knox
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09 Feb 2007 03:38 AM

All we need is $$$$$$$$$$$.

Padgett, if you and pops ever feel like puttin that trucking sticker on the side of a hydro let me know. Speaking of which, we could sure use a transporter and a driver. rolleyes



Eddie Knox Racing
Problem Child TFH #712



www.eddieknoxracing.com
Problem Child TFH #712
Pro Flat Gold Memeber Gold Memeber Send Private Message Posts:33 Pro Flat
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28 Mar 2007 06:49 PM

I like this topic...  Being in the design side of the aerospace industry, this is something I have thought of from time to time.

 

In my opinion, car's go for the lightest equipment because of the excessive down force they make.  There is no penalty for lightening the chassis / motor.  If they begin to have problems keeping the tires gripped to the road due to aero issues, they just add a bit of spoiler.  (I know I am oversimplifying)

 

Boats have to maintain a balance of lift and down force all the way down the track, and maintain the balance in a variety of water conditions.  The lift generated by the sponsons in the water + lift generated by the air flowing under the boat + lift generated by the prop(s) = roughly the down force of air running over the deck.  If this balance is off by a large margin, nothing bad really happens at low speeds, the boat just doesn’t 'fly' right.  At higher speeds, the balance obviously becomes more important, and the aero penalty for the imbalance gets higher, resulting in the two extremes: submarining the boat, or flipping it over.  (this assumes CG is correct for the application)

 

I would think that the heavier hulls are a product of the water conditions at speed, and not necessarily because of the loading factor benefit on the motors, although the statements about it helping the motor stay loaded sound right.  You could conceivably design a very lightly laid up boat, and stuff it with titanium everything, to maximize the hp / weight ratio, but you could only run the boat in the best of water conditions. 

 

As far as what’s left on the table in terms of aero, the biggest thing that sticks out to me in terms of things that are needed for outright speed is the cowling between the capsule and the motor.  Any streamlining that can be done from the back of the capsule to the transom will help, the important thing to remember is avoid having voids in the air stream (why the cowling is needed), and to have smooth transitions wherever possible, no 90 deg transitions.  In the end it’s all about how much money you want to spend, but if you are asking about the biggest bang for the buck, the cowling is #1 and any mass aft of the motor to the transom (to smooth out the airflow) is #2.

 

And not to get off topic, but can anyone explain why the new outrigger fuel boats are considered a TFH?  The way an outrigger generates lift and stability is different enough from a hydro that I think they are a new subclass and would call them a TFO...

 

Anyways, I have only been in this sport for a few years, and these are just my thoughts, so I welcome any feedback or corrections.

 

Thanks. 



On this trailer....you know the rest !
Greg May Send Private Message Posts:489 Greg May
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29 Mar 2007 02:15 PM
I'll take a stab at this.  I think Hydro refers to hydroplane.  And from the best of my knowledge “hydros” have a ride plate attached to each sponson to lift the boat at speeds.  While some do trap air I think the plate enable the proper angle so that they can trap air.  So going by this it might just mean that any boat with two plates might be considered a hydro.  So that is how the Outriggers are still considered a Hydro.  There are several different types of hydro hull out there.  I have no clue how many but they all are a little different.


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BAF316PE Send Private Message Posts:557 BAF316PE
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29 Mar 2007 02:39 PM
mustoer said...

 

In my opinion, car's go for the lightest equipment because of the excessive down force they make.  There is no penalty for lightening the chassis / motor.  If they begin to have problems keeping the tires gripped to the road due to aero issues, they just add a bit of spoiler.  (I know I am oversimplifying)

 

I cant really speak for other race cars but TF dragsters have a weight limit w/driver and they are also limited to rear spoiler angle. The amount of tire spin is absorbed thru clutch managment.


Sean Barnes
Physi-COLE ATTRACTION
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TAF/316
Canyon Boats
TAF 535



Daniel L. Ellison Send Private Message Posts:106 Daniel L. Ellison
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31 Mar 2007 02:54 PM
An outrigger is basically just a hydro with no wing(airtrap).They could be made lighter,as they are less affected by airflow. The first couple that I have built are overkill(3000+wet),There is alot of room for weight savings. Also the complaints I have gotten from engine tuners is,the boat is too efficient so we can't keep 8 lit. This tells me an outrigger could stand more gear and prop(load). This has been a HUGE learning curve, fuel boats are strange beasts. I applaud all those that can get one down the track.


Pro Flat Gold Memeber Gold Memeber Send Private Message Posts:33 Pro Flat
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04 Apr 2007 04:28 PM
I was commenting on the differences between the lifting forces on an outrigger hull versus a traditional hydro hull when the boat is at speed.  Namely the Hydro's use of the front wing/tunnel , and the outriggers use of the larger, wider sponsons that stay in the water.

To me, (again I come from a background in aerospace design, so I might be commenting on things that are out of my sandbox), the differences between the 2 hull types (w.r.t. lifting forces) are large enough that I would consider the outrigger to be a new class of boat, not a variation of a hydro. That’s why I said I wouldn’t necessarily call them a TFH.  I wouldn’t put them in a new, separately run class, as I would compare it to running flats and hydros in the same bracket class.

 

Regarding the comment about the boats being too efficient for the fuel motors:  Isn’t there some way to keep a load on the motor without going to a larger gear or changing the prop setup?  Something like a Non-contact torque sensor on the driveline that controls a magnetic brake on the driveline (same sort of braking setup that is used on some of the highspeed cars/trains/airplanes)...  This would put a constant load on the motor and the sensitivity could be adjusted so that it responded fast enough to do the job...

 



On this trailer....you know the rest !
JT69383 Flat-Out Send Private Message Posts:525 JT69383
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04 Apr 2007 07:27 PM
By definition, a hydroplane is a motorboat that has been designed to skim long the surface of water.
 
I DID A REPORT ON THIS IN HIGH SCHOOL AND BUILT AN OUTBOARD 2 POINT HYDRO (GOT AN A+). OUTRIGGERS STILL QUALIFY IN MY HUMBLE OPINION, THEY ARE 3 POINT HYDROS JUST LIKE THE REST OF THEM.
 
SORRY ABOUT THE FONT, IT CARRIED OVER FROM THE WEBSITE I GOT THE DEFINITION FROM.


John Thompson
 
'an old guy with an old boat'
 
Clear Lake, Northern California
   



An Old Guy with an Old Boat
'69 Agua Craft
Clear Lake
The other Dunn Old Timer Old Timer Send Private Message Posts:90 The other Dunn
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04 Apr 2007 08:48 PM

 

 

          Here it comes BARNES!

   (Non contact torque sensor)...OK... Like D. E. said if it floats its a boat..if it has sponsons its a hydro!...Im not speaking for D.E. because his boat was designed after the Radio control boats which are more of a true Outrigger. I built mine to my own specs because I knew they would be a hard sell, the first person ever get a look at my idea on paper was Harold Kindsvauter and he tore it apart.

  The sponsons shoes and gliders are almost the same as (Wolfies) just a little longer...they measure the same distance over the top as the bottom...equal area so I consider them neutral as for lift. On a run the boat rides on the shoes, very little but on the shoes. The Big advantage D.E.s boat and the BULLET have over the Barndoors is.... (They spill air and are a lot more forgiving in case of big problems).... like breaking a prop shaft off at 250 plus unloading and returning to the water to race again. Or the rudder going full left, putting the boat 90 degrees to the coarse and not crashing...Luck is a factor but show me any other boat that has gotten away with any of these stunts and not crashed. It seams as though everything that could happen has happened to the BULLET, Daryls in the seat driving and Dennis throwing money at it, and its always their at the end of the day for the finals.

   TEAM...DRIVER...BIG D...OUTRIGGER...if it floats its a boat nothing special just a hydro!

   



Scott Burrows Send Private Message Posts:1442 Scott Burrows
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04 Apr 2007 10:26 PM
Wildside lost strut and prop shaft on a 246, 4.77 run in Phoenix '01, ended up on the beach but stayed straight.


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Pro Flat Gold Memeber Gold Memeber Send Private Message Posts:33 Pro Flat
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09 Apr 2007 06:29 PM

Regarding the non contact torque sensor / magnetic brakes, if keeping the motor loaded really is a problem for TF boats, and the same clutch setup that’s used on cars doesn’t work in boats, then the torque sensor and magnetic brakes would be a solution (certainly not the only one).  Its the first thing I think of because that’s my professional background (electrical / computer engineering), although now I play with planes.

If you want to see something similar to what I was thinking about, do an internet search for 'Futek t5400'.

It is rated to 10000 in/lbs of torque...  I haven’t done enough research to say this is what would work, but the interface/design is similar.

The output of the sensor (voltage) is read by a micro computer which in turn controls the magnetic brake (by limiting the power applied to the magnets).  You could put one brake on the driveshaft (next to the torque sensor) or maybe on the output of the w-drive (or wherever there is room).

There are probably a ton of ways to do something like this, I was trying to think of a way to remove the mechanical interfaces so parts wouldn’t wear out.

Of course, if this isn’t a problem, then consider this just an academic exercise.



On this trailer....you know the rest !
Greg Padgett Send Private Message Posts:372 Greg Padgett
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10 Apr 2007 03:50 PM
if you ever need a drive i am sure we could work out that padgett sticker on the sidescool
P.C. said...

All we need is $$$$$$$$$$$.

Padgett, if you and pops ever feel like puttin that trucking sticker on the side of a hydro let me know. Speaking of which, we could sure use a transporter and a driver. rolleyes


NOTHING TURNS ME ON LIKE NITRO AND DIRTY STRIPPERS I LOVE THOSE STRIPPERS

CAPSULES WHO NEEDS THEM



NOTHING TURNS ME ON LIKE NITRO AND DIRTY STRIPPERS I LOVE THOSE STRIPPERS

CAPSULES WHO NEEDS THEM
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