Rigger question...

[6cuda6]

I admit i'm not all that fussed on riggers but after looking at some of them [PHM"S or eagle etc] i could probably find one a home but i have a design question for the rigger experts....

1- how come there is no off set in the front spondons??? the boats turn to the right so how come no hull off set to the right???

2- there seams to be lots of effort into getting the front ride pads on the spondons just right...why not make the rear boom servo adjustable so the spondons can have a pitch change???

3- looking at the various riggers some have rear spondons others don't...what the value of them???

thanks for the info......Dean

 

[TomMoorehouse]

I admit i'm not all that fussed on riggers but after looking at some of them [PHM"S or eagle etc] i could probably find one a home but i have a design question for the rigger experts....
1- how come there is no off set in the front spondons??? the boats turn to the right so how come no hull off set to the right???

2- there seams to be lots of effort into getting the front ride pads on the spondons just right...why not make the rear boom servo adjustable so the spondons can have a pitch change???

3- looking at the various riggers some have rear spondons others don't...what the value of them???

thanks for the info......Dean

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1) most do have an offset

2) most use shims under the tubes to allow adjustment

3) rears.... it's all up to the designer.... different applications, different desgin goals.

 

[gil sonsino]

Some designs use paralelism others off set for the front sponsons.

Personally I prefer the first one once you have the turn fin left veering the boat and with the anti walk strut you can have your boat going straight effortlessly.

A well balanced and sharpy propellor also will minimize the prop walking.

Most of the riggers have fully adjustable booms so you don't need the rear boom servo adjustable mainly because there is no room in this kind of boat and it would be needed a ton torque servo to hold the boom static.

rear sponsons work during lauching untill the boat gets on plane & in turns once most of the time they are in the air(in straights).two or three rears are great for heat race and one is perfect for straights.

Gill

 

[ClayGlover]

Hey Gil, I'll ask you or anyone who knows, since I get a reply from Andy Brown about 1 in 3 times if I'm lucky . What makes the "anti-walk strut" work as an anti-walk strut? The extra length? Thanks

 

[Preston_Hall]

Hey Gil, I'll ask you or anyone who knows, since I get a reply from Andy Brown about 1 in 3 times if I'm lucky  .  What makes the "anti-walk strut" work as an anti-walk strut?  The extra length?  Thanks

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Good question. It might be magic since the strut isn't in the water.

My boats quit walking when I learned how to set them up correctly.

1- how come there is no off set in the front spondons??? the boats turn to the right so how come no hull off set to the right???

With proper setup there is no need. Also, the weight displacent doesn't seem to be much of an advantage at our scale speeds. Ask this, why would you at this point?
Also, when things are not staright the boat seems to be in a bind going down the straights and then it just exhibits unwanted traits.

 

[Brad Christy]

Dean,

Offset sponsons is a thing of the past, in my opinion. originally, the idea was to apply leverage on the left sponson to keep the boat level in the turns, and not let the turn fin lift out. A good turn fin design will do this for you all by itself. This is not to say that someone with offset sponsons is using a bad turn fin design, just a different method of overcoming lateral inertia.

As for the "on-the-fly" sponson adjustability: forget it. The beating the servo would have to endure would kill it in a matter of laps. You usually find the correct attack angle and leave it there. The main reason for any adjustability is to tweak it after ass'y. Some people make tiny adjustments depending upon running conditions, but they are usually VERY familiar with their boat.

The rear sponsons, like already stated, are primarily for launch. They also serve to keep the prop from digging too hard in the turns or in rough water. If designed right, and the angle is correct, they will actually control the overall ride attitude of the boat, using aerodynamics, hardly ever touching the surface of the water. In this case, you can think of them as the "flights" on a dart or arrow.

This is my spin on these issues. Hope it helps.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

 

[6cuda6]

Thanks guy's....to the untrained eye, except for shapes the riggers all look the same [design that is]... you've explained exactly what i was after and also why the "S" rigger never really to off....

Has anyone ever tryed making the front spondons steerable??? i'm only talking about 10 or so degrees...it would be mainly to speed up steering and to carve a cleaner arc as opposed to pushing the front end? something along the lines of a 4 wheel steer car.....

 

[Mike Hughes]

A properly setup rigger does not need all that much input from the rudder to turn the corner.

There is going to be a lot of load produced by the turn fin on the right sponson. Again you are going to have problems with a servo to take a beating if you try and steer the sponson. Sometimes you need to go with the KISS theory.

Mike

 

[Mark]

The amount of adjustment in the rear boom is very minimal, you can make it adjustable by machining up a accentric cam setup. Fairly simple and would not give the servo a hard time at all provided you gave the cam a total of about 1.5 to 2mm total adjustment in height which is heaps if you're anywhere near close. But I don't really think the advantage would be considered a plus because of the extra weight for the servo and cam setup. On the flip-side it would be good at the start or if you're out infront all alone you could trim it to run light and if you start getting into traffic or chopped up water u could settle the boat down a little so you could still run hard. Just a thought.

 

[Rickracer]

Here is a boat using that idea. I don't think it's done and tested yet, but it should be pretty interesting: http://p086.ezboard.com/fjimsrcboatdockfrm...icID=3865.topic .

At this point, the sponsons don't steer, but they are adjustable, and suspended. B)

View attachment 4178

 

[ken t.]

Thanks guy's....to the untrained eye, except for shapes the riggers all look the same [design that is]... you've explained exactly what i was after and also why the "S" rigger never really to off....
Has anyone ever tryed making the front spondons steerable??? i'm only talking about 10 or so degrees...it would be mainly to speed up steering and to carve a cleaner arc as opposed to pushing the front end? something along the lines of a 4 wheel steer car.....

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Funny you should mention steering the sponsons. I was going to try that very thing myself, It would likeley have to be a gas boat or a 90 size since you'd likely need a couple of 1/4 scale servos to handle the steering.

 

[PHM Racing]

99 % Of todays riggers have no problem turning if there is a problem it's that they can turn to tight.

A well set up rigger will not need the front sponsons to turn.

 

[AndyBrown]

Hey Gil, I'll ask you or anyone who knows, since I get a reply from Andy Brown about 1 in 3 times if I'm lucky  .  What makes the "anti-walk strut" work as an anti-walk strut?  The extra length?  Thanks

96590[/snapback]

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Good question. It might be magic since the strut isn't in the water.

My boats quit walking when I learned how to set them up correctly.

1- how come there is no off set in the front spondons??? the boats turn to the right so how come no hull off set to the right???

With proper setup there is no need. Also, the weight displacent doesn't seem to be much of an advantage at our scale speeds. Ask this, why would you at this point?
Also, when things are not staright the boat seems to be in a bind going down the straights and then it just exhibits unwanted traits.

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Anti-walk strut? Good question. I will talk about why it does work sometime in the next few days when I've got a little more time.

Preston...It is Magic! hehe

I'll give you something to think about for now. If you run a hydro with the Drive Dog (not the prop) even with the back of the transom and then run the same boat set up with the drive dog 2" behind the transom you will see a difference in the way the boat handles. The effect of the prop is exerted on the bottom of the transom.

Even though the transom is in the "air". And even though the prop is BEHIND the transom in both cases.

Outboard racers could benefit from understanding the effects the prop excerts on the harware in front of it.

 

[ClayGlover]

Cool

I can say this, after putting one of them on my 40 rigger, I can pull props that I couldn't turn before and it definitely made this boat handle rough water better.

Strange thing is I have to add some RIGHT trim to keep it straight now :blink: . I think some assymetrical attack angle or toe change is needed to correct my problem.

Well, I don't have a propwalk problem, that's for sure .

 

[Don Templeton]

Can't wait to hear Andy's comments since I'm one that likes to have the drive dog up close to the transom. Oh well live and learn! :lol:

Don

 

[ClayGlover]

LOL, ok, the pull to the right was a big sponson AOA error on my part, nothing to do with the strut... user error on the digilevel I looked at the boat from the front and the sponsons were so cockeyed it was funny. doh

 

[Preston_Hall]

Andy,

I'm all ears.

 

[topfuel443]

"Outboard racers could benefit from understanding the effects the prop excerts on the harware in front of it." ~ Andy Brown

Im all ears Andy!!!

BTW what ever happend to the outboard that you and John were playing with?? Did you get it in the water yet? Did you find it easier or harder than expected to get good handling/speed out of an outboard/tunnel hull??

~James

 

[Don Templeton]

Just bumping this up so Andy will see it.

 

[John Finch]

Hey Gil, I'll ask you or anyone who knows, since I get a reply from Andy Brown about 1 in 3 times if I'm lucky  .  What makes the "anti-walk strut" work as an anti-walk strut?  The extra length?  Thanks

96590[/snapback]

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Good question. It might be magic since the strut isn't in the water.

My boats quit walking when I learned how to set them up correctly.

1- how come there is no off set in the front spondons??? the boats turn to the right so how come no hull off set to the right???

With proper setup there is no need. Also, the weight displacent doesn't seem to be much of an advantage at our scale speeds. Ask this, why would you at this point?
Also, when things are not staright the boat seems to be in a bind going down the straights and then it just exhibits unwanted traits.

96592[/snapback]

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