Tunnel Hull Design

[RonShaw]

The old Aerotech SR-360 molds were purchased by Jim Iriwin at one time. Not sure of their where a bouts now. That is an old one there. Thoes molds were built around 1984 or 85. They may not pull a straight part by now??? That was a "Low Air Tunnel" It took a screamer O/B to get it up and rolling.That's why it finished a lot of windy races when many others got a big fat D.N.F. under thoes conditions.

-Carl

Carl,

With that thinking in mind, think about that hull with one of today's Q FE motors!!!! It would jump out of the water and on plane very quickly. That's exactly what I am looking to build......

 

[dave roach]

Jim Irwin still has the molds and as far as I know the molds are still in good shape.

Dave Roach

 

[Carl Van Houten]

The Savage would be a good design for the Q class. It was a consistant finisher in most conditions. I gave thoes molds to a friend of mine about 18 years ago and he hasn't made but a couple of the Savage 360 boats since then because he got into racing R/C cars so the Savage molds should be in good shape. I may see what is going on with that. The Hornet

was another good rough water racer. I sold the Hornet molds a few years ago but I am not sure if they are still in working order or not. I haven't heard of anyone buying a new one in years.

-Carl,

 

[David Moyle]

Well this thread has been quiet for too long. We can't let it sit for 3 years!

I'm not sure what other people have been up to - my life has been pretty busy with our young kids but always tinkering around with tunnel design when I get a rare spare moment.

I'm working on a new hull for our 3.5cc Sport tunnel class here in Oz. Slightly lighter build than my mod Breakthrough tunnels have been. Centre section is essentially the same, however the sponsons are different. Constant deadrise angle from the back to the front, and the sponsons get wider towards the front, with the widest beam being about in line with the front of the centre section. They are as yet untested but should be getting wet in about a month or so.

 

[Kris Flynn]

Great to see some more things coming out of the Breakthrough stables!

I have said it before Dave, but it is going to be a good year for Tunnels in Australia

 

[David Moyle]

Yep I can't wait to have some good racing against the Dragons!

 

[Frank Wayland]

Interest in the tunnels is growing in the NW USA as well. There were 3 or 4 at my first race last may. I jumped in with a VS1 and by the end of the season there were two 5 to 6 boat heats running. More builds going on this winter so spring should be interesting. They really are fun to drive and much different than Hydros.

Frank

 

[Christian Lucas]

Hi,

as i have experiment lot of things with tunnelhull to use them on the NAVIGA triangle F1 racecourse i will show some of my results.

On the triangle you have to do 6 120 degree turn and one 180 degree U-turn in boht direction allways at full throttle. World record for this 200 meter race is less 10 second by Chinese driver . My Prather 21 tunnel perfomed verry well . For high speed turns i used outrigged turnfin on both side behind c.g. .For ovalracing on the right side . As tunnelhul like to get moore grip at the front during cornering that will spin the boat inside i use big wedge at the front of the sponson that prevent the sponson from diving to deep in the water .This worke allways best on Prather with it wide sponson and on tunnelboats from AMPS the 21 Velden tunnel and many other .

in the last couple of years i run tunnel with a third ski in the middle of the tunnel . It's just a ski,made of wood oor aluminium that has a bigger angle of attace as the sponson outside. So at full speed the tunnel rides only on the aft sction of the ski and the sponson do not tough the water. And as the ski has a higher angle of attace the tunnel rides better levelt over the waves

 

[Christian Lucas]

moore pics from the ski and the spin prevent wedge.

The ski is made from aluminium and mount on small distance holder on the tunnel floore, And water and air can flow from ech side nearly free under the tunnel space. i set the ski deeper than the sponson at the transom to lift the boat high out the water at high speed. As the ski has a higher angle of attace related to the sponson ,the tunnelhull runs moore parallel to the water surface and the ski at a low resistance angle of about 3-4 degree.my tunnels run moore stable with this ski and turn on a dime .

 

[Kris Flynn]

Bringing this wicked thread to the top for any of the newer readers to have a lesson

 

[Julio Almazan]

Hi:

Bringing this wicked thread to the top for any of the newer readers to have a lesson

I am very interested in this new concept of Tunnels !!!
Thank you very much for uploading it again

 

[Carl Van Houten]

When you have steps on your sponsons and a center pad that lifts the rear of the sponsons clear of the water you actually have a hydro that looks like a tunnel boat.

 

[Grimracer]

As long as the keel line is not broken or added to.. is it a step? In this case I say yes, it is a step.

Grim

 

[Carl Van Houten]

As long as the keel line is not broken or added to.. is it a step? In this case I say yes, it is a step.

Grim

You are right Mike, It is a step plus its being used as a fulcrum point to break the water away from the rest of the sponson thus keeping it from touching the water and that makes it a hydro.

Allowing a step on the sponson bottoms of a tunnel boat can get into the fudge zone very quick especially in timed events. We have seen this done already and you can't stop it through a protest because once you open the rule book you quickly see that the rules that govern the tunnel boat sponson can be interpreted to allow them so what do you do? How many tunnel boaters want to change the rules? LOL That would be a HUGE FIGHT and that is why they are still sketchy when it comes to what the word "continuous" actually means.

This needs to change but it will require some interest and some effort. The first thing you will hear is "It's been that way for years so why change it now"? I for one would love to see it change because when someone designs a true tunnel boat (one that rides one the rear of the sponsons and with no steps on the bottom) and they take it to a SAW event and have to compete with a time that was set by a hydro that looked like a tunnel boat that guy will probably not be very happy.

-Carl

 

[Mark Poole ModVP]

Life size tunnels have steps, usually just one or two per sponson. If you look in the NAMBA rules I think they limit how deep they can be. If you made the step VERY deep then you would have a four point tunnel boat. The boat in the pics with the strip of metal making a ski in the tunnel is illegal. That makes it a hydro. Of course anything is allowed in open hydro, except a mono. Some tunnels have the drop down steps near the tips but are not in contact with the water unless the water is very rough which can help prevent the boat from stuffing. I say we consider a "Classic" tunnel class. No steps, belly pods, blocks or pickle forks. True full tunnel. I wonder how many of you could make that work!

 

[Carl Van Houten]

95% or more of R/C Tunnel Boaters these days are not builders and less than that are building prototype models for testing purposes. Most people that you meet at races have purchased their boats. I wish more people would scratch build models to race.

 

[Kris Flynn]

95% or more of R/C Tunnel Boaters these days are not builders and less than that are building prototype models for testing purposes. Most people that you meet at races have purchased their boats. I wish more people would scratch build models to race.

I had hoped that by sharing my tunnel plans it would encourage more people to scratch build their own versions and try their own things. But I have not seen or heard of many people, other than Manuel in Portugal who has build a stretched version for gesr drive 20 setups they run.

But, the carrot is always there haha