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Hi,

have talked with a guy from Munich University Aerodynamics he designed some world champion pylon racer planes. He say ,that the deck is producing lift but the relation to the lift created by the tunnel is like nothing . So no lift from deck is OK .

Happy Amps Christian
 
Interesting read guys,

Best in a long time from some heavy hitters

In the tunnelhull world......

Gene
 
Hi ,

i want to give you a little rethought about tunnelhull design. Tunnelhull tend to make a spin out . The reason is that the front part of the sponson grab deeper and deeper in the water and the outborder skeg can not hold the back . With an early tunnelhull i run a simple brasstube outbord with no skeg and the tunnel don't spin out . The reason was that the sponson had a deep v at the back and no v at the front of the sponson. With no V the front didn't grab deep in the water like you most do with a aditional wedge in the tunnel. I think you need no wedge ,the sponson V can do the same.

To improve very narrow curve drive i adopte the idea from Ed Fischer ,the turnfin on the outrigged position. The turnfin hold the boat and also prevent it from spin out if it is placed behind the c.g. .

For the European F1 triangl race i ad a turnfin a each side to get good tunrability in both ,left and right hand , turns .

The pics show the old tunnel with the changing V

and i have modifide Kris plan that show the flat front sponson modification.

Happy Amps Christian

2014-07-14 22.19.41.jpg

2014-07-14 22.19.03.jpg

IMG_2348.PNG
 
This is a typical "norwegian" hull style for triangle corse racing. Does not spin out unless you lift the outboard too high.
This very different from the US hull style design. It is not an ultrafast design, but it has very good handling.

54.jpg

55.jpg

56.jpg
 
Christians modifications to my design would be pretty good i think...maybe an angle inbetween and make to pad on the left sponson wider by 10mm or so for the front 1/3rd.

That is a beautify hull Joern...very good craftsmanship by whoever built it.

I tried a design of ride pad angle similar to that on my dragon 2 revisions before my current M11 (technically the design after what is attached to first post). I could not get it to corner the way I wanted it to so the belt sander changed a few angles and the M11 prototype was born :)

Maybe one day a dragon will be raced in your country to see how it goes.
 
Hi Kris,

yes you can simply glue some hard foam on the sponson and cut angles like you want . There is a lot of experiment open to find the best angle and wide .

Happy Amps Christian
 
Hi,

would be good if Jerry Dunlap can contact Jay Selby . He wrote a very good artikel about aerodynamics of tunnelhull in RC-Modeler mag. Most influence about lift was the design of the tunnel it selve.see pic. .How to accelerate or to slow the airflow will rise presure or reduce it . I have test some of Jays design rules and they have all worked as he wrote. With this i would never place a wedge inside the tunnel . I have allways ad such wedge on the sponson at the front . For super high conering i also used turnfins , position after the c.g. . I have run a Prather 20 size tunnel in the Naviga F1 class and reached best time 12,2 seconds . The current record was in this class 11.1 second ,but this was with a full submerged propeller monohull that was spezial for F1 made. My tunnel run with a K&B lower ,a Octura 1250 with big cupping , prop. This tunnel run left and right hand corners as well with no spin out.

Little draw: at nr.1. the airflow will slow and the pressure rise and the result if lift the boat at this position.

Happy Amps Christian
The fastest outboard tunnel 2-lap times ever recorded (to this day anyway) had a wedge in the tunnel.
 
Carl,

Having said that and based on Tommys comment.. I suspect the wedge shape was arbitrary or had little to do with aero.. but likely not in mechanical strength.

I like trapezoids or triangles for strength... might be a huge advantage to your designs..

Grim
 
Hello Kris-I was just making a "blanket statement" that seems to me like everyone is trying to make a tunnel boat that looks fast &"zoomie" sitting on the table but making no progress on the water. This could be a controversial subject and some probably will not believe what I say but I don't care . I know what I have learned. I have no desire to get into a big discussion over this. (I'm too old) I do have access to wind tunnel data that was taken from a model of a full size boat and from what I know this is the only time this has been done. I do not own the data and I cannot and will not share the info on an open forum. However, all the aero principles that have been around for years and apply to airplanes, cars, trucks, etc. also apply to tunnel boats. There are no big secrets out there. I will share a couple of facts that may surprise you-maybe not. 1-a tunnel boat is not a good aero design. 2-the deck shape above the tunnel floor does absolutely nothing to affect performance, lift or anything. 3-you CAN NOT CREATE LIFT from the deck of a tunnel boat. 4-the cowling has no lifting capabilities and Kris as you have stated the boats work pretty good without them. Maybe a small increase in drag. A few things to think about.
I have worked on tunnel hull aerodynamics for the past 20 years and it is what keeps me interested in the sport. I have learned many things about these persnickety little boats because I don't accept ANYTHING that I can't prove to myself. Yes I am hard headed. I have a wind tunnel that I test and prove all my boats on. It came with several variable surface texture settings and air speeds but I am not able to set them because they are randomly set by the guy who made it for me. The last tunnel boat design that I just recently finished is called the Taboo MR 300 (MR for Mike Rushing) This was the last project we worked on together before he passed. This boat challenged all my knowledge about boat design big time and I ended up spending 9 years in development (off and on) and 5 molds before I finally got what I originally set out to build. I learned a piece of the puzzle with each change I made. What I had originally set out to do by building the Taboo was to make a boat that was superior to the performance of the Lynx. This is why it took so long to accomplish. So far only two boats have come out of these new molds.

People who run my Lynx and who also know how to set them up correctly... will tell you that they can actually see the aerodynamics taking affect and working on their boats as they near the ends of the straights while driving them. You will never get this to happen unless you have a boat that is what I call neutral. Meaning the top and bottom of the boat are working together to the same degree "at a given speed". When you get to this magical point, you can push it faster than ever because everything is working together instead of one over powering the other as the speed increases. When I design a boat, I am all over it. Meaning, I am working it from all aspects of its shape, length, width, weight etc. leaving nothing out while trying to get the model to behave in a certain way. All of this effort only gets the initial prototype close to this point because believe me this is just step one of a long project when trying to tame a tunnel boat. The sleek resulting look of the boat is just what works best.

As Kris mentioned in his post about his cowling having little affect on his boat... When a boat is being controlled mostly by its hydrodynamic footprint, then aerodynamic changes may not have as much of an affect on the model and vice versa. This is not intended to be a slam to his model because the Dragon can run hammer down around the track and finish in some nasty water. We have been watching the performance of this boat and agree that at the end of the day, it is a good round track boat. When you get your model performing equally between these two effects (aerodynamically and hydro dynamically netural) is when you can really start to work on subtle changes that allow you to fine tune your model. This takes time and LOTS OF IT! You do not always make progress as it is easy to branch off into what you think is a "fix" to a problem only to learn later that you have been working on an "effect" the whole time and not the real root of a undesirable trait.

If you want to design, build and perfect a model tunnel boat, get ready to spend years doing it because if you throw one together and it is the best tunnel boat ever made in its class; you will not need to think that it will ever happen again. If it does, you would be better off using that kind of luck buying lottery tickets because take it from me, you will never make enough money from selling models to pay your bills.

But now to each his own. I'm not knocking anybodies designs or ideas. I think everybody should have their own ideas because that is what makes designing and building and racing tunnel boats fun.

See you at the time trials!

-Carl
Hi Carl,

Since we are talking about designs and such...please do not take this in a bad way, but what happened with the THOR line up? Why were most of those turds on the water? Was it incorrect builds? Rushed into production? other?

Always wondered why it never took off and now you do not offer it anymore.

After talking to someone about 'wedges' used in many industries with someone I work with, we are now interested to see what actual effects we can gain from them, along with other 'aero' tweaks in the tunnel. I know stumble blocks for one, are not just an aid for turning
default_smile.png


Cheers

Kris
 
Hello Kris-I was just making a "blanket statement" that seems to me like everyone is trying to make a tunnel boat that looks fast &"zoomie" sitting on the table but making no progress on the water. This could be a controversial subject and some probably will not believe what I say but I don't care . I know what I have learned. I have no desire to get into a big discussion over this. (I'm too old) I do have access to wind tunnel data that was taken from a model of a full size boat and from what I know this is the only time this has been done. I do not own the data and I cannot and will not share the info on an open forum. However, all the aero principles that have been around for years and apply to airplanes, cars, trucks, etc. also apply to tunnel boats. There are no big secrets out there. I will share a couple of facts that may surprise you-maybe not. 1-a tunnel boat is not a good aero design. 2-the deck shape above the tunnel floor does absolutely nothing to affect performance, lift or anything. 3-you CAN NOT CREATE LIFT from the deck of a tunnel boat. 4-the cowling has no lifting capabilities and Kris as you have stated the boats work pretty good without them. Maybe a small increase in drag. A few things to think about.
I have worked on tunnel hull aerodynamics for the past 20 years and it is what keeps me interested in the sport. I have learned many things about these persnickety little boats because I don't accept ANYTHING that I can't prove to myself. Yes I am hard headed. I have a wind tunnel that I test and prove all my boats on. It came with several variable surface texture settings and air speeds but I am not able to set them because they are randomly set by the guy who made it for me. The last tunnel boat design that I just recently finished is called the Taboo MR 300 (MR for Mike Rushing) This was the last project we worked on together before he passed. This boat challenged all my knowledge about boat design big time and I ended up spending 9 years in development (off and on) and 5 molds before I finally got what I originally set out to build. I learned a piece of the puzzle with each change I made. What I had originally set out to do by building the Taboo was to make a boat that was superior to the performance of the Lynx. This is why it took so long to accomplish. So far only two boats have come out of these new molds.

People who run my Lynx and who also know how to set them up correctly... will tell you that they can actually see the aerodynamics taking affect and working on their boats as they near the ends of the straights while driving them. You will never get this to happen unless you have a boat that is what I call neutral. Meaning the top and bottom of the boat are working together to the same degree "at a given speed". When you get to this magical point, you can push it faster than ever because everything is working together instead of one over powering the other as the speed increases. When I design a boat, I am all over it. Meaning, I am working it from all aspects of its shape, length, width, weight etc. leaving nothing out while trying to get the model to behave in a certain way. All of this effort only gets the initial prototype close to this point because believe me this is just step one of a long project when trying to tame a tunnel boat. The sleek resulting look of the boat is just what works best.

As Kris mentioned in his post about his cowling having little affect on his boat... When a boat is being controlled mostly by its hydrodynamic footprint, then aerodynamic changes may not have as much of an affect on the model and vice versa. This is not intended to be a slam to his model because the Dragon can run hammer down around the track and finish in some nasty water. We have been watching the performance of this boat and agree that at the end of the day, it is a good round track boat. When you get your model performing equally between these two effects (aerodynamically and hydro dynamically netural) is when you can really start to work on subtle changes that allow you to fine tune your model. This takes time and LOTS OF IT! You do not always make progress as it is easy to branch off into what you think is a "fix" to a problem only to learn later that you have been working on an "effect" the whole time and not the real root of a undesirable trait.

If you want to design, build and perfect a model tunnel boat, get ready to spend years doing it because if you throw one together and it is the best tunnel boat ever made in its class; you will not need to think that it will ever happen again. If it does, you would be better off using that kind of luck buying lottery tickets because take it from me, you will never make enough money from selling models to pay your bills.

But now to each his own. I'm not knocking anybodies designs or ideas. I think everybody should have their own ideas because that is what makes designing and building and racing tunnel boats fun.

See you at the time trials!

-Carl
Hi Carl,

Since we are talking about designs and such...please do not take this in a bad way, but what happened with the THOR line up? Why were most of those turds on the water? Was it incorrect builds? Rushed into production? other?

Always wondered why it never took off and now you do not offer it anymore.

After talking to someone about 'wedges' used in many industries with someone I work with, we are now interested to see what actual effects we can gain from them, along with other 'aero' tweaks in the tunnel. I know stumble blocks for one, are not just an aid for turning
default_smile.png


Cheers

Kris
Kris,

I stopped building laser kits because I can't make any real profit on wooden kits compared to my fiberglass models. If you don't own a laser, the cost of a kit eats most all the profits away not to mention that the market for wooden tunnel boats is nothing compared to fiberglass models. Yes, your right...I made some changes to my kits. Have you ever made changes to yours?

You seem a little hostile for some reason. What makes you this way? I don't think there is anybody on here that wants to see me and you go at it like a couple of pre schoolers. I certainly will not take that bate and be a part of something like that. I have no issue with you. Try to bring your act up a notch Kris. You don't hear me bashing your products or any products for that matter. I hope that you can find a way to be more helpful to our sport and for the readers of this forum rather than electing to lash out and trashing people.

-Carl
 
Hi Carl,

This was not a bash, it was a question. People talk to me about it all the time, but I never see anyone ask the real questions. Think of me as the voice (or ugly head) of the crowd. I do not need to bash your product. You do however have the best running and most decorated design by far under your belt, no body can take that away from you.

I couldn't care less for hostility these days, I have better things to waste my time on these days
default_smile.png


You are right about the laser cutting being chunk of the pricing of a laser cut kit. Then having to deal with someone else and being at their mercy sucks!

I have actually made no design changes since my M11, M13 and M18 designs came out. I thoroughly tested and raced them before official release to ensure I had the best product I could have at that time. Only changes have been tweaks to make the build easier and using better quality wood.

now, as for this line

Try to bring your act up a notch Kris. You don't hear me bashing your products or any products for that matter. I hope that you can find a way to be more helpful to our sport and for the readers of this forum rather than electing to lash out and trashing people.
I feel people just try to bring me down when they look at my posts as a negative, how about you just see it for what it is? A simple discussion into why a design did not work. I know I would be happy to discuss why a design of mine did not work out the way I had intended it to. Not everything has to be progression. Look into all the larger/more informative outboard/tunnel boat threads over the last few years....who started them??

Look at this thread we are currently posting info into...I think me giving out FREE plans is a huge positive. I know a few people who have already build them and had them running very well.

Anyway, I had assumed the response could go either way...but hoped you would see it for what it was...
 
Just to add...I realize my wording in the original post/question above was not the brightest. I see that would not have helped with your response Carl. Sorry about that.
 
Just to add...I realize my wording in the original post/question above was not the brightest. I see that would not have helped with your response Carl. Sorry about that.
Thanks for the complement Kris.

I have gone to races where people had their Lynx jumping and acting a fool all over the pond and could hardly finish a heat and all I had to do to correct their problem was to wet sand the bottom for 3 to 5 mins and tweak the prop and boom... she was a rocket ship. The difference between a poor running boat and a fantastic running boat can be as little as .005" in the right place on a tunnel boat that trims on the "heels" as mine do. But on a wooden boat designed like this, it is not so easy to do because as you know, a few licks with some sandpaper and you're into the wood grain. This makes working the bottom of a wooden boat very hard to do if the bottom is the slightest bit off once you finish it. At one point I had thought about supplying my kits with two fiberglass panels such as a thin strip of G-10 instead of plywood for the sponson bottoms in order to make working the bottoms easier to do but by that time I realized that the wood kits were more trouble than they are worth in a profit sense for me so I elected to just stop and get back to my glass models. I believe that it actually cost me $35 dollars to sell my THOR 470 to someone once its all said and done. I mostly use my laser models for prototypes now and it is a great tool for that in my case.

-Carl
 
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I've built over 16 tunnels in the last 10 years - all have been electric. I have rigged 2 Dragons in the last couple years for someone in our club. A year ago I bought a Thor kit - I raced it the last 2 club races in 2016, and raced it the last 8 races this year. I also own a Lynx, and the Thor is probably 8 ounces heavier. The Lynx may be a little faster on top end. Both boats are set up as spec boats and running Lawless outdrive. They run 59+. I can be more aggressive with the Thor. In our club there are 3 Dragons, 2 Lynx, 1 Cobra, 1 LM Boatworks, and 1 TopSpeed3. I know driving skills help a lot, but not one of these other club boats has driven around me yet - as Carl says "Drive one or chase one..." If anyone has any questions about setting up a Thor or Lynx for electric, call me 360-876-5711.
 
Just to add...I realize my wording in the original post/question above was not the brightest. I see that would not have helped with your response Carl. Sorry about that.
Thanks for the complement Kris.
I have gone to races where people had their Lynx jumping and acting a fool all over the pond and could hardly finish a heat and all I had to do to correct their problem was to wet sand the bottom for 3 to 5 mins and tweak the prop and boom... she was a rocket ship. The difference between a poor running boat and a fantastic running boat can be as little as .005" in the right place on a tunnel boat that trims on the "heels" as mine do. But on a wooden boat designed like this, it is not so easy to do because as you know, a few licks with some sandpaper and you're into the wood grain. This makes working the bottom of a wooden boat very hard to do if the bottom is the slightest bit off once you finish it. At one point I had thought about supplying my kits with two fiberglass panels such as a thin strip of G-10 instead of plywood for the sponson bottoms in order to make working the bottoms easier to do but by that time I realized that the wood kits were more trouble than they are worth in a profit sense for me so I elected to just stop and get back to my glass models. I believe that it actually cost me $35 dollars to sell my THOR 470 to someone once its all said and done. I mostly use my laser models for prototypes now and it is a great tool for that in my case.

-Carl
So alot was to do with the build or builder rather than design. I can 100% understand how not sanding the bottoms flat and not having straight and sharp edges on the bottom drastically effects some boats.
 
Let me know who has downloaded the plans and are tempted to build one??
I will Krys. Here in Portugal there are two dragons built from the scratch (one is mine) and soon they will be on the water. You did a great job of divulging the modality posting this plans and also very important helping and giving advices. Dragons forever
 
Let me know who has downloaded the plans and are tempted to build one??
Kris,

I think that you providing a free kit to boaters is actually a great thing. I have a lot going on right now but I want to follow your lead along with a couple of others designer/builders on here that are doing the same thing as well. I have one in mind and when it gets cold this winter, I will get this kit together and make it available in PDF.

-Carl
 
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