Where do we Go From Here?

[TUNLBOTR]

Im VERY anxious to see how Marty Davis's new boat runs.......could be the next level.......my GOD its light!

Got to fondle the Cougar to day.

David

Take that stuf to off topic you PERV.

Did Marty watch?

buncha sick pups on here.

 

[Archie Stanton]

deleted

 

[Ron Olson]

I have to agree with Archie.

I've mentioned this before; the late Ric Carpenter had a .21 'rigger thaqt was shaped more like a submarine on sponsons than the boxes that we're used to and the thing was crazy fast with a tired K&B. Had he done more work on it insted of quitting when it got rear-ended after losing a flex cable no telling what its future could have been. Look at the Team JAG record-setter and you'll see more rounded parts than pointy ones. There are a few designs that are in the FE crowd with 'glas hulls with a more modern design.

In order to think outside the box you need to get rid of the box.

 

[Charles Perdue]

While I do say clean aerodynamics is important, the hydrodynamics is WAY more important. Water is over 800 times more dense than air so the main drag stuff from water is a bigger deal to solve. Aero will be a factor, lift I would say is the most important part, aero drag is not as big of deal really.

Aerodynamics is very important. Controlling the air above, around and below the hull and sponsons is essential to creating and controlling a high pressure area beneath the boat. This lifts the boat slightly which makes the boat run like it is much lighter on the water, reducing the hydrodynamic drag.

The boat may look something like this.......

I agree

Aerodynamics is where it's at.....

I just cant see any more speed gained from where the boat touches the water......unless some genius figures out to touch the water less times and still be a hydro

Look under the boat in the pic.....only things touching the water is the turn fin, prop and rudder.....

This is the way it runs down the straightaways....just touching the sponsons ever once in a while for balance.

 

[dwilfong]

This looks promising.

 

[Charles Perdue]

This looks promising.

A good step in the right direction, but it still has long flat sides on the sponsons and hull and its shape is not aerodynamically neutral.

 

[dwilfong]

This looks promising.

A good step in the right direction, but it still has long flat sides on the sponsons and hull and its shape is not aerodynamically neutral.

I have bin scratching around in my head of building a wind tunnel. With three load pads on the floor. Should not be too much trouble considering the small size it would be.

 

[Charles Perdue]

This looks promising.

A good step in the right direction, but it still has long flat sides on the sponsons and hull and its shape is not aerodynamically neutral.

I have bin scratching around in my head of building a wind tunnel. With three load pads on the floor. Should not be too much trouble considering the small size it would be.

I have been using my "WALMART" wind tunnel for a while now. The blower has a gas engine and the tunnel is cardboard, plexiglass and duct tape. I can generate up to 80 mph wind thru a 6"X6" tunnel. It could be a much better, but I have learned a lot using it.

 

[Tony Jacuzzi]

My son (Eric) did some CFD markups and modelling of some of the SAW sponson and boat designs that we had seen at Flint, and a set of M Nowicki 21 SAW sponsons that I have. (Eric is currently working on his Masters at the University of Michigan in Aerospace Engineering). The results were very interesting and a lot of the shapes that we thought would be aero slick had a lot of room for improvement. It was really pretty interesting stuff but he is so busy with full time work and full time at the U of M that the project has been filed for the future. He is convinced that there are aero opportunitys out there for our boats... . Tony J

 

[Jorgen Andersson]

Hello

Interesting subject....

Enclosed is a picture of the hydro 21 that Carl mentioned.

This was designed and built by Anders Ydergard from Sweden.

I think the first major outing was the European Cup way back in 1984.

I have more pictures and a drawing if someone is interested.

If memory serves right, I think that is was fast and stable, but nothing out of the ordinary.

I agree with Charles and others about the Aero, this is the key to control the total drag and handling. It is not difficult to built a hydro that has very low hydrodynamic drag, the problem will be the handling of the boat in rough water, racing water, and having very good control in the corners when driving in lane 1 and passing other boats.

Power and speed is nothing without control in 8 boat heats with several good drivers.

As I see it you must have a certain amount of water penetration in order to have a good handling boat for racing, if it is too light, you will end up with several DNF´s.

The AoA is getting higher and higher, and we have been able to handle this without blowing off by new designs.

Chris - Shocks....yes...*smile*

Enclosed are two pictures of my latest hydro 21 called HydroShock 21.

Round boom tubes have one Aero advantage, the give the same drag/lift at any angle.... but several racers have used better Aero designs with good results.

All my comments are made with 6 lap heatracing in mind, not SAW or time trails.

One problem with todays racing is that the cornering speed and the speed at the straights are almost the same. If you don´t take the start and the racer in front of you is fast and a Lane 1 racer, it is very difficult to overtake even if you have reeled him in.

Charles design and handling could be a step in the right direction for this.

One thing that I found very important in order to keep the race speed up all the time, is that the prop stays well hooked up all the time. When you get unhooked, even very little, you loose very much speed/drive at once. Many hydros have been passed when they get unhooked, even just for a very short time.

Jorgen

 

[Archie Stanton]

deleted

 

[PropNut]

Chris Harris carbon rigger circa 2007. Helld the IMPBA electric SAW record at 111 mph for 3 years. Many interesting Aero design features.

All the best,

Ray

 

[Charles Perdue]

That is a very good SAW design.

He also reduced the rear drag by elimating the flat transom. The flat rear of the boat creates a strong low pressure area behind the boat that acts like a suction, slowing the it down.

I looks like that he recessed the transom so that he could mount the hardware farther forward so he could taper the rear. This is very important in allowing the air to come back together with minimum turbulence.

 

[dwilfong]

I saw a boat at a local RC boat builder that had a split tail on it. It was a mono but was intrigued by the design. I was told it was designed by a person working at NASA in a wind tunnel.

David

 

[Charles Perdue]

There is a lot of info avaliable on some of the NASA sites...........

 

[dwilfong]

There is a lot of info avaliable on some of the NASA sites...........

I know was given some info on down loads of airo programs. Will start to mess with them real soon. Wish I had more free time to play.

The X1 was based on a 50cal bullet profile. Seams that this would be a good way to think on tub and sponson design.Air foil would be nice but you need to have control in race water. Like what was said you have to turn in rough water. We already use the turn fin to hook in the turn and control boat attitude in the turn why not get rid of the sponson and just use the fin. With nothing riding on top of the water waves would be taken out of the equation. I was thinking of a flat arch from the tub to the water with a T foil on the end. The arch would act as a shock kinda like a torsion bar.

David

 

[Martin Hamilton]

A more aero shape is only going to increase speed a small amount over a slightly less aero shape. How we run the tethered hydros is aero shaped this includes fully cowled engines & pipes which also helps with noise levels that we have to keep to 80db at 22metres. But the biggest increase in speeds are seen in trim of how the boat rides. We run them with the sponsons just hovering of the water so just riding on one prop blade. The most single important part to do this is the rear horizontal wing.Think Ken Warbys world record holding full size jet boat that had this type of wing, We were useing these wings long before. Its a reverse aero foil (upside down wing). The idea of this is that you can trim the boat,Sponson shapes & angles, hull shape top & bottom,tether points & hights & C/G.By altering the angle that the wing sits at determins how much the front lifts above the water & should the front start to come up to high the wing is working all the time to trim the boat to its given trim or ride level. We have been useing these wings for around 30 years now and would never run or could run a tethered hydro without one they also help stabalize the rear end of the boat and stop the prop from jumping. This is all assuming you have every thing sorted on the boat and adding this wing will not turn a bad design or set up into a good one allthough it will improve even a bad running boat or prop. Bearing in mind this is all on tetherd boats.Regards Martin.

 

[Charles Perdue]

Hello

Interesting subject....

Enclosed is a picture of the hydro 21 that Carl mentioned.

This was designed and built by Anders Ydergard from Sweden.

I think the first major outing was the European Cup way back in 1984.

I have more pictures and a drawing if someone is interested.

If memory serves right, I think that is was fast and stable, but nothing out of the ordinary.

I agree with Charles and others about the Aero, this is the key to control the total drag and handling. It is not difficult to built a hydro that has very low hydrodynamic drag, the problem will be the handling of the boat in rough water, racing water, and having very good control in the corners when driving in lane 1 and passing other boats.

Power and speed is nothing without control in 8 boat heats with several good drivers.

As I see it you must have a certain amount of water penetration in order to have a good handling boat for racing, if it is too light, you will end up with several DNF´s.

The AoA is getting higher and higher, and we have been able to handle this without blowing off by new designs.

Chris - Shocks....yes...*smile*

Enclosed are two pictures of my latest hydro 21 called HydroShock 21.

Round boom tubes have one Aero advantage, the give the same drag/lift at any angle.... but several racers have used better Aero designs with good results.

All my comments are made with 6 lap heatracing in mind, not SAW or time trails.

One problem with todays racing is that the cornering speed and the speed at the straights are almost the same. If you don´t take the start and the racer in front of you is fast and a Lane 1 racer, it is very difficult to overtake even if you have reeled him in.

Charles design and handling could be a step in the right direction for this.

One thing that I found very important in order to keep the race speed up all the time, is that the prop stays well hooked up all the time. When you get unhooked, even very little, you loose very much speed/drive at once. Many hydros have been passed when they get unhooked, even just for a very short time.

Jorgen

Looking good Jorgen.....

I am glad that you decided to get back into boating.....from the looks of your boat, you may have been teasing us into thinking that you were out of boating while you were working on your new designs all of the time.....

 

[Jorgen Andersson]

Hello again

Martin - Yes, I agree, this could be a good thing for RC hydros.

I have done some yet early tests with a rear horizontal wing with a moving elevator, similar to an airplane.

I have tested and used it fixed as you use them on the tether boats, but I have also had it adjustable by radio as a trim for the ride level.

I have some pictures of the system, I will see if I can post some tomorrow.

This worked really well, so I will continue to test more during the summer.

Any chance you could post some pictures of modern tether boats? I have earlier looked at them for inspiration, but at the moment my update is poor.

Charles - Thank you for the nice words, it is appreciated. As we had said before, you and I think alike many times......

It would be really interesting if you could tell us some more details around your new boat and how the testing goes.

Thanks

Jorgen

 

[Martin Hamilton]

Hi Jorgen go to onthewire.co.uk then click on hydros on the left side of the page then scroll down to infomation sources & click on A3 tethered hydroplane, Also click on classes & records & theirs some pictures of modern boats. Regards Martin.