3.5 Tunnel SAW record

[zuber]

The lakes must be frozen in alot of places

 

[Slideblues]

Yep Does it show that bad ? :lol:

 

[Preston_Hall]

Less slippage.

To do a little promoting and to set the record straight........

Just for everyone's information,most of the fastest boat speeds in IMPBA have been at the Huntsville pond.

The fastest recorded pass of 126mph was in Elizabeth City, NC. The fastest 1/3 mile oval in Chesapeake, VA. Also in IMPBA hydro and mono classes A-F Huntsville has only 4 of 12 SAW records and 6 of 12 1/3 oval records. The Elizabeth City, NC lake and the Chesapeake, VA lake (both of Old Dominion Model Boat Association) are still the fastest bodies of water for the A-F classes and hold 12 of the 24 forementioned records. So I would say that it depends on what event the redcord setters attend more so than the water density.

 

[GTR]

Hi Guy's

I'm no hydrodynamic expert but I would think the denser water results in less prop slippage than clear water. It does not require more HP to turn the prop but more torque. More bouyant water should play in to the hands of tunnel speedsters as the power can go towards moving the hull forwards rather than lifting it out of the water. Denser water creating more drag? don't think so as most of the hull is flying. This would be totally contrary on a displacement hull but that isn't the case here. Aerodynamic drag is more of an issue for tunnels as they move accross rather than through it.

Think of it as sand - I'll bet you can run a lot faster across grasss than you can across sand. You can only develop the same (person) horsepower but you go faster. Improved efficiency for your feet.

That's my take on it anyway.

GT

 

[Propjockey]

It's all about variables. As bouyancy increases, wetted surface (and drag) decreases. Again though, only to a point. Put a tunnel on a pond of Jello. "Wetted surface" is tiny...edge of the keelsons only. Will it go faster? Kinda doubt it.

I think you're absolutely right though...aerodynamic drag is a huge factor on a tunnel travelling at 70 MPH. Especially when you consider the amout of hull exposed to water compared to the amount of hull exposed to air.

Propjockey Racing.....where the he!! am I going with this?!!

(Yes Dear, I'll clean up the mess when I'm done)

 

[Terry Keeley]

Less slippage.
To do a little promoting and to set the record straight........

Just for everyone's information,most of the fastest boat speeds in IMPBA have been at the Huntsville pond.

The fastest recorded pass of 126mph was in Elizabeth City, NC. The fastest 1/3 mile oval in Chesapeake, VA. Also in IMPBA hydro and mono classes A-F Huntsville has only 4 of 12 SAW records and 6 of 12 1/3 oval records. The Elizabeth City, NC lake and the Chesapeake, VA lake (both of Old Dominion Model Boat Association) are still the fastest bodies of water for the A-F classes and hold 12 of the 24 forementioned records. So I would say that it depends on what event the redcord setters attend more so than the water density.

Hope to get to run at Elizabeth City one day, being at sea level vs 650' for Huntsville or 800' for Flint has to be a bonus.

 

[Lake S.P.O.R.T.]

Lifesize and RC boats run faster on saltwater, mainly because of the bouyancy. I used to have a 60 size hull that i ran a 40 motor on years ago and the speed difference on saltwater was noticeable even without a radar gun. Where i am located is about 400 ft. above sea level. I would not think that that would make much difference. At what point do you think altitude would really start to play a big part? 1000 ft. 2000 ft. ??

Mark

 

[Slideblues]

I would like to hear a little more on the design element. I agree about the water being a factor, But ya got the hydro and aerodynamics,

What's it gonna take design wise to accelerate one to the speed needed and keep the dang thing on the water is my question.

Gene

Length 30"

Deadrise less than 12 degrees

Thin frontal area

What else ?

 

[Jerry Dunlap]

I'd put notches in the sponson running surface and outer sponson strakes parallel with the tunnel floor.

JD

 

[Grimracer]

Gener

13 flat

30" long....not sure this is needed but...cant hurt

2/10ths tunnel AOA

RTR weight at under 4 lbs

Non pointed anything in front but small frontal profile

5/8 tunnel depth...could be less

Props 4 you prop.. i would like to see a 1640 done up like Tommys record prop. But Genes H4 is a good one and should do the deed

Nova built by Rod G just for SAW

K+B foot

Noisy fricking nitro pipe like the Rossi small volume.

Test

Test

Test....

Grim

 

[Slideblues]

Thats interesting JD

 

[Slideblues]

Hey Mikie,

Yeah I do like the shallow draft, I'll have to look up the specs we used on the tunnel depth, But that does sound very close, Ditto on the Rossi pipe, and ride surface,

Gene

 

[Slideblues]

Hmmmmmmm...... 1640 is what Tommie used?

One thing I am comfortable with on the H-4 is, its pretty neutral on the way it handels, No bad habits, but the other sounds interesting too,

Gene

Thats prob back to the progressive vs. fixed pitch thang

 

[Preston_Hall]

So if you can get the speed but the boat blows over, why not reposition the CG without adding any weight.

My thoughts have been to trash the current outdrives and lay the drive shaft out to more of a straight line. This will move the engine (CG) forward and keep the same prop location.

 

[Slideblues]

Hi Preston,

I made the radio box a tray, and then a smaller box adjustable to set CG

and held in place with velcro, The outdrive idea sound's interesting

 

[casey]

i'm at work so i can't measure it, but what's the deadrise and tunnel depth of a villain? thanks

 

[Slideblues]

Hey Casey,

I'm at work too, A stock Villain Im guessin bout 3/4" depth and 14 degrees deadrise,

Gene

 

[Geraghty]

I was talking to Tommy Lee last night and we both were commenting on this thread and the interest shown by some of you to go record hunting.

Tommy and I have been racing partners for a long long time but unfortunately we both have been relegated to being second-hand lions.

The knowledge is there but the passion is waining.

I am going to try to post some photos.If that works then,if you are interested, later tonight or tomorrow I will give you some tunnel history that goes back over 25 years and facts regarding tunnel boat design that Tommy and I know to be facts.

There is no doubt that a 3.5SS or O.S.3.5 can go 55+[i have done it on radar],

a 3.5 Mod.will easily go 70+ and a 7.5 Mod tunnel can run 80.

My next post will be a photo ......I hope!

 

[Geraghty]

Photo #1 This boat has been 55+ on the Stalker Radar gun.

 

[Geraghty]

Photo #2