Doubts on plans

[carlosam]

I'm new here at the forum and will be someone who could give me an explanation of position of propellant as the scale?

I was reviewing the plans of hydro Ted Jones and noticed that the scales of 1/10th and 1 / 12 th the propellant is in line center while on the scale of 1/16th is shifted to the right in .375 ".

The Pay'N Pak in 1/8th scale and 1/10th are on the line center, the 1/12th is shifted .50 " to the right and 1/13th .056."

What is the reason for the shift?

[NativePaul]

A design error or a copy of a full scale design error, it should be offset on them all.

[carlosam]

Okay, I understand ... a design error or a copy of a full scale design error, it should be offset on them all, but what is right? What do I do? What design is correct? This is my question ..... all plans the propellant is displaced? If yes which the displacement?

[NativePaul]

Is the rudder on the left, right or behind the prop? I run my rudders on the right so have to offset the rudder and turn fin drag as well as the prop walk, 3mm for every 4inches of beam works well for me.

[carlosam]

I'm damned !!!!! I have no experience in making these boats, for example, I intended to mount the atlas is 1/16th and the rudder is shifted to the left 1.5" and propulsion to right .25", I can follow the plan then?

[NativePaul]

With the rudder on the left you would certainly need less prop offset to the right than I use, .25" sounds reasonable.

[Tappy]

I'm damned !!!!! I have no experience in making these boats, for example, I intended to mount the atlas is 1/16th and the rudder is shifted to the left 1.5" and propulsion to right .25", I can follow the plan then?

Yes, those dimensions seem correct for that boat. Have fun building!

[Garry Finlay]

Sorry to have missed this post by a few days. Some boats benefit from a driveline offset more than others. A short boat that uses a large propeller may produce more prop walk than a longer boat that swings a small, sharp propeller at high RPM.

Any of the boats built from these plans will track straighter with less rudder trim when a small driveline offset is used. Note, that the plans that show driveling offset assume that a propeller will be rotating counter clockwise when viewed from the rear (standard for most model boats).

You could leave the offset out of any of these and still have a nice running hull. Mostly, boats with high power-to-weight and large wheels will benefit from a bit of offset. Leave it out and all you have to do is dial in a bit of rudder trim (with a corresponding small amount of drag) to get your boat to track straight.

Garry

[Allan]

Garry is the designer and has I think run all the models that he has designed. Garry has offered a view here that he knows works but that may not be the whole story. You may wish to set your boat up differentlt and use offset weight to compensate for centripetal force in turns etc. This vcan affect the straight line run and may mean that your best run position involves more or less offset.

The rudder position changes the way the boat corners and that has an effect as well - my preference is to have the rudder as near in line with the turn fin as I can get it as I feel the boats crabs slightly in turnd when it is far away. My preference and so I build like that and make the necessary compensations. I also build to race so will offset the weight to compensate for ovals and prop lift/walk. If you build for scale look then you would not do this as the boat can look odd at stand still - and you would also have the turn fin on the other sponson and follow normal fullsize build and maybe an alternate prop that means the offsets will be the other way.

The standard builds here are for "race and sport" set ups and are great for that but it will not stop you having to fiddle with yours as no two boats are exactly the same - even if they come out of a mould.