Sponsons and Tub Tips

[LohringMiller]

"I like the old methods....reality.

Drive down the road 85-90 mph and stick a 2 ft piece of boom tube out of the window... "

I like real world testing as well. Where is the water when you use uour method? How close is your object to the water surface? How will you measure the performance of a real hydro under actual conditions? We ran a multi year series of test programs that investigated a lot of these things. Our data collection methods started with a radar gun and onboard tach and ended with onboard data logging and an engine dyno. We tried a lot of off the wall things like various air traps, rudder designs, and engine modifications. Some were worthless and some worked surprisingly well. The ratio was around 5 worthless to one good idea. The result was a record that stood for around 14 years. The GX1 gas sport hydro and 3.5 outboard hydro records still stand.

Lohring Miller

 

[dwilfong]

"I like the old methods....reality.

Drive down the road 85-90 mph and stick a 2 ft piece of boom tube out of the window... "

I like real world testing as well. Where is the water when you use uour method? How close is your object to the water surface? How will you measure the performance of a real hydro under actual conditions? We ran a multi year series of test programs that investigated a lot of these things. Our data collection methods started with a radar gun and onboard tach and ended with onboard data logging and an engine dyno. We tried a lot of off the wall things like various air traps, rudder designs, and engine modifications. Some were worthless and some worked surprisingly well. The ratio was around 5 worthless to one good idea. The result was a record that stood for around 14 years. The GX1 gas sport hydro and 3.5 outboard hydro records still stand.

Lohring Miller

Yes nothing like real world testing with a boat on the water.
The simpler it is the easier it is to make adjustments.
It looks good on paper till it gets wet........LOL

 

[KenOlvis]

After being out of the Hobby so long an reading on the forum here I see
1) hulls are bigger an lighter (dang wide track lol)
2 )clean way of fasting the radio lid
( dang screws would twist the Hull out of square needed to pay attention.
3)So much info available today.
4 ) Still a hobby for most.
As for the Hull an sponson tips make it square.Velcro the shape on the tip make several shapes test test an retest
For most running the boat is funnest way to se results.
Remember a helicopter can't fly in theory. Or was it a bumblebee.
Hope to get wet.

 

[Wasted wages]

Helicopters just fly because they beat the air into submission....


You'll never catch me on one of those deathtraps.

 

[brad nichols]

I know that Andy Stechenko?? from AC boats use to take a can of bondo to the lake when he was testing new boats.

Brad

 

[darryl whitman]

hi guys , I'm thinking simple here, we are working with 3 elements, 1 gravity, weight of the boat, 2 water friction, hydro dynamics, 3 airflow, aerodynamics,
all 3 work against movement , keeping us from GOING FAST, like I said - Im thinking simple rain drops may have some answers . all 3 forces are working here,
if we could come up with a way to change the foot print of the bottom of the boat , wide plan to lift the boat up - than narrow it for speed once the boat is running , also be able to redirect airflow to increase or decrease lift. an we think lighter is faster, debatable, I found in flying lighter is not really good on some conditions , gravity can be good for controlling the unit. we see this a lot , build real light boat , runs fast skipping along than pow aerodynamics takes over.
ITS A PLANE , lol speed dies off than gravity , we have all seen it . just my thoughts .

 

[KenOlvis]

Was anyone tried to dimple the surface of the Hull or sponsors like a golf ball
Research shows that dimples have a diameter of approximately 3.9 mm, and have depth of 0.15 mm. Without dimples, a smooth golf ball has a volume of 38,792 mm3 and a surface area of 5,542 mm2.

Less surface to have affects of the elements

 

[darryl whitman]

Ken Im going to try 2 methods, 1 mixing sand in the epoxy for the bottom of the sponson , also cutting a 15 degree grooves from the tub out on the sponsons,
Shingling is also an idea too

 

[KenOlvis]

Shingles work for me.

 

[KenOlvis]

Be reading more about the effects of the dimples

 

[dwilfong]

I built a ,21 rigger with a lattice work side frames covered with CF. then I put shingles on the bottoms of the sponsors in two rows on the outer edge to make a tunnel.
Even put the K&S aerio foil tubes on the booms.
Still have the boat.
Took the shingles off the sponsons made it to light on the water.
YES to light.........
Took the foils off the boom tubes also.
Did not race well like this.
Over all none of the trick stuff mad a rats ass difference in the boat as far as how it raced.
Just made it harder to try and set up.

 

[darryl whitman]

Shingles work for me.View attachment 290576

thats funny . lol

 

[darryl whitman]

Be reading more about the effects of the dimples

maybe I will try this on the top an sides of the boat.

 

[Chris Wood]

yrs ago in testing sponson's on my 21 hydro i tried wrapping the tubes in thin brass sheet stock all the way around encasing the tubes it immediately made to much lift. so there are things there to play with, just depending how much time you want to spend

 

[John Beardslee]

If I remember right, a round tube has 9 times more drag than a given airfoil of the same cross section so I think for SAW it’s something to consider. I saw a gas rigger with carbon fiber airfoils on the booms that were free floating. It ran 117mph right off the bench.

 

[Brad Christy]

yrs ago in testing sponson's on my 21 hydro i tried wrapping the tubes in thin brass sheet stock all the way around encasing the tubes it immediately made to much lift. so there are things there to play with, just depending how much time you want to spend

I would think a relatively short airfoil, relative to the diameter of boom tube to be covered, would minimize lift, while also minimizing drag. Obviously, some trial and error would be required to find an acceptable balance. All we're looking for is to reduce the Bernoulli affect as much as possible without unmitigatable lift. Additionally, if one were to tune the angle to produce downforce, instead of upward lift, This would almost certainly help in negating any unwanted influence.

Thanks. Brad.
Titan Racing Components
BlackJack Hydros
Model Machine and Precision LLC

 

[Hydro Junkie]

I may not run riggers but some of this I've heard before when discussing full sized unlimiteds and scale boats.
Way back in the 1950s, there was an argument over the shape of the deck. One school of thought was that the deck needed to be arced higher for more deck pressure to hold the boat down while the other called for lower to allow the boat to fly more. It seems that aerodynamics were being looked at back then as well. This lead to wind tunnel testing of a model of one of the boats back in the late 80s(don't remember if it was the Circus or Budweiser)where it was found that a round edge worked better than the sharp when it came to air flow around the sponsons. I don't know if any of that was done with the bulnose shape or not, just that the various boats now have changeable bulnose covers that will change the shape and depth of the bulnose so there has to have been some testing done with that as well. It seems, however, that aerodynamics are more of a design issue than hydrodynamics since, once on plane, hydrodynamics really don't affect the boat that much unless there is enough "chop" to change the boat's attitude. This is borne out by the fact that the unlimited boats of today have become more aerodynamically thought out on the right side of the boat hulls than the boats from decades past

 

[bermudadude]

yes my dad used to tell me about the wind tunnel testing half my life or more ago. so its waayy not new. shingles adjustable canards and rear wings n all.
on the topic of engines i remember him telling me once there will never be nothing new before internal combustion is obsolete...its just new to the public .
most of that (both hull design and engine) is because the exotic materials needed to get the small angles and small cross sections and details + the tech to measure all the angles and tiny thicknesses is only now becoming available and affordable to the average person.
think about it ,carbon fiber developed for the stealth fighters now available for us crazies to make boats . u wouldnt have dreamed of it back in the day. same with good billet alloys and the tiny millers and lathes that can fit in ur house and use regular 120v power and not need a nasa super computer ,any modern laptop will do . we all have access to CAD and all the programs for cnc .
only difference is now u can actually build the engine and hull of ur great grandpas dreams right in ur yard and not at area 51 lol
my dad did a few trips to an evenrude factory n he learned about stuff that he told me about that ive been seeing introduced in production engines over the years .
if u search the net for random racing stuff u find lots of archived info with the old pics. crazy to see how old some stuff is .
lotta crazy trix with hulls. like because of the heavy materials back then -air tubes from the deck to the running surfaces,have to put em in the right place or u loose control because the boat becomes a hover craft .
prop wont pull out the hole -send air into the blades under the cav plate.
cant turn at speed put on the water break- a tiny inch or so dia cylinder stuck out the bottom of the boat . breaking power so unpredictable they banned it ,somebodies boat disintegrated because it wanted to stop too hard .
lots a stuff out there

 

[Hydro Junkie]

Shawn, did we kill this thread? After you and I posted, it kind of died

 

[bermudadude]

lol wouldnt say that .
these days the homemmade or mod threads are always slower.
what with the ready to run and cookie cutter generation.
just gotta go with the flow i guess