Twin .45 Design

[Jeff Schindler]

There was some discussion of .45 twins going on in this thread starting at post #29 http://www.intlwaters.com/index.php?showtopic=53461&st=15&do=findComment&comment=501952

I've not seen one that was very impressive yet. But, I've thought about building a Multi-Engine, and I've got 2 Novarossi .46's that I've been tooling around the idea with for a while.

I have some questions about design that could make or break this project.

(1) How best to cope with the weight disparity 11 lb vs 16 lb? The race water will be choppy, will making the boat larger than needed be beneficial? Lets say I can get everything balanced out in a 40" boat, should I still go with a 45" boat? larger? Of course it will be a struggle to keep props hooked up, but other than that does size matter?

(2) Countering Prop torque. I'm going the traditional twin engine/ twin props/Normal rotation. What is the best way to keep torque steer down, or counter act it? Rudder size, COG bias, biased lift, and biased downforce considered. I've been following the SAW mono topic for a while, and have learned a lot from Andy Brown and John Finch's back and forth. Thanks Guys!!!

I'm going to try and start laying things out soon, so If any guru's would please comment here, it would be awesome!

 

[ALLAN YUEN]

I looked at David Pressue JAE 45 Twin at hobart . It is nice red and use KB.45 modded engines and run good stable. I made laugh at him because he feel shake his body " crazy fear" so he put two engines into pocket pant and easy relax body down

 

[Joe Warren]

jeff if you are designing your own boat? Carefully select your front sponson width to carry the weight of the twin engines and fuel needed. CG? engine placement? Ski? NO SKI? Many things to consider when you have twice the weight. If you see a Good Running Twin any engine size??? It has been tried and tested many times by many boaters, for many years........... it does NOT happen overnite!!!!! slight changes can change it all.....

 

[ALLAN YUEN]

I had sold my very rare SGX45 TWIN with MAC45 to Europe last three yrs ago . It was very good fast but hardly find .187 cable drive 30" . I ordered special cables through Andy Brown

 

[Jeff Schindler]

Allan, thanks for the pictures. That is a long boat! I like the design, and am going to try something very similar with 2 ski's. I am thinking of using a CG farther back and experimenting with different sets sponsons. I won't know exactly until I start laying it all out and trying to get the balance right.

Joe, You definately know how to make them work! It would be nice to build something the first time and have it work great, but I would be a fool to think thats going to happen. I am going to try and make things modular so I can change them out and try different things.

 

[Andy Brown]

Our current Twin 45 SGX is 41". It is based off of our single 80 boat. Allan's boat looks about the same. We have built so many different verssions of the twin 45, many times custom built to what the customer was looking for. We had built some based off of the 67 boat (37.5") but they were just a little to small for some race situations. We had also built some 43" T-45's based off of the 90 boat, but I really like the newest 41" Twin 45. If it is built clean it will come in at 10 pounds even.

Our Twin 67/84 SGX is 42".

 

[SayMikey]

There was some discussion of .45 twins going on in this thread starting at post #29 http://www.intlwater...=15#entry501952

I've not seen one that was very impressive yet. But, I've thought about building a Multi-Engine, and I've got 2 Novarossi .46's that I've been tooling around the idea with for a while.

I have some questions about design that could make or break this project.

(1) How best to cope with the weight disparity 11 lb vs 16 lb? The race water will be choppy, will making the boat larger than needed be beneficial? Lets say I can get everything balanced out in a 40" boat, should I still go with a 45" boat? larger? Of course it will be a struggle to keep props hooked up, but other than that does size matter?

(2) Countering Prop torque. I'm going the traditional twin engine/ twin props/Normal rotation. What is the best way to keep torque steer down, or counter act it? Rudder size, COG bias, biased lift, and biased downforce considered. I've been following the SAW mono topic for a while, and have learned a lot from Andy Brown and John Finch's back and forth. Thanks Guys!!!

I'm going to try and start laying things out soon, so If any guru's would please comment here, it would be awesome!

OMG this coming from some one who told me I was nuts when I brought home a twin....Get the glue out

 

[Joe Warren]

There was some discussion of .45 twins going on in this thread starting at post #29 http://www.intlwater...=15#entry501952

I've not seen one that was very impressive yet. But, I've thought about building a Multi-Engine, and I've got 2 Novarossi .46's that I've been tooling around the idea with for a while.

I have some questions about design that could make or break this project.

(1) How best to cope with the weight disparity 11 lb vs 16 lb? The race water will be choppy, will making the boat larger than needed be beneficial? Lets say I can get everything balanced out in a 40" boat, should I still go with a 45" boat? larger? Of course it will be a struggle to keep props hooked up, but other than that does size matter?

(2) Countering Prop torque. I'm going the traditional twin engine/ twin props/Normal rotation. What is the best way to keep torque steer down, or counter act it? Rudder size, COG bias, biased lift, and biased downforce considered. I've been following the SAW mono topic for a while, and have learned a lot from Andy Brown and John Finch's back and forth. Thanks Guys!!!

I'm going to try and start laying things out soon, so If any guru's would please comment here, it would be awesome!

OMG this coming from some one who told me I was nuts when I brought home a twin....Get the glue out

IT IS A FEVER MIKE! sorta like cat scratch fever.

 

[julianconde]

Jeff build you a Twin 21 i have one and we can race each other for fun

 

[XtremeRcBoats]

Allan, i think your old twin 45 was raced this year at the world championchips by Jorg Banaszak:

 

[XtremeRcBoats]

Jeff, also have a look at the Jae twin 45 design:

http://ne-stuff.blogspot.nl/2012/02/jae-45-twin-pdfs.html

 

[Andy Brown]

Allan, i think your old twin 45 was raced this year at the world championchips by Jorg Banaszak:

The very first Twin Eagle SG was built for Jorg Banaszak in 1996. It had K-90's for power.

 

[Jeff Schindler]

Here's a sneak peak. I got a little carried away with modelling the engines, but they look so good next to each other!

 

[ALLAN YUEN]

Allan, i think your old twin 45 was raced this year at the world championchips by Jorg Banaszak:

WOW Yes my ex- SGX 45 Twin long 43" B)

 

[Thomas Hulbert]

Here's a sneak peak. I got a little carried away with modelling the engines, but they look so good next to each other!

View attachment 41235

Wow looks good , Just one thaught pipes should point the other way though. :blink:

 

[ALLAN YUEN]

Here's a sneak peak. I got a little carried away with modelling the engines, but they look so good next to each other!

View attachment 41235

figure out where place for tanks on the tub?

 

[stan simpson iv]

I would guess in the same area...just the pipes are going to be right above the tanks. Several people have tried that and have had good results. I hope it works for you,with the pipes going forward sounds WICKED when you come down the front straight away for the start of a race. Please keep us posted on your build..thx you

 

[ALLAN YUEN]

Al Hobbs showed me his new custom" Justin" 45 Twin with A/A.45s He will try run it at our district 16 in 2013

 

[Jeff Schindler]

Al Hobbs showed me his new custom" Justin" 45 Twin with A/A.45s He will try run it at our district 16 in 2013

Cool headers! WICKED, I hope so Stan! I will try and fit the tanks under the pipes, and If I have trouble, I might see what some side pods look like.

 

[ALLAN YUEN]

will you may try build homemake 4 gear wheels box on your NR46s as same as Europe gear box monos

will you try build homemake gear wheels box on your NR46s as same as Europe gear box monos Do you think good idea ??? Contact to Terry Keeley he had experince with 20 momo before Good Luck!