Got some rigger question! ON JAE and other riggers..

[misshydro]

Ok..Whats the purpouse on the hole openning on top of the cowl? for water in the cooling botton out? Two, one like the JAE rudder bracket and on some other rigger I see some use carbonfiber or 3/16 ply that glued or bolted on the tube sides.What size of ply should be used and how to attached it ,screws or epoxy and how well do they hold up? These are asked by joe. He's trying to get his rigger done..from the pics he got the scoop for fresh air and closed off the backend of the cowl to trap air in for the carb.He was thinking on getting a 90 water outlet. put a tube on it and drill a small hole on top of the cowl for the tube to go threw. Any advice would be greatfull.

 

[Blackout]

My thoughts are that your scoop will cause some drag. I don't think you need a ram air affect for 2-strokes...

 

[misshydro]

My thoughts are that your scoop will cause some drag. I don't think you need a ram air affect for 2-strokes...

The reson why joe did that so air can get in..since no hole on top.

 

[Ted buckley]

Nessa, I was looking at the pic - is it a .12 or .21 JAE? I use NO water on my .12 - period(unless it's 95 degrees). So, I don't think a water relief should be a problem. Secondly, the Ram air is for looks only, but if your going to have an opening in front, you should have some relief in back. Air will get in there regardless if you had an opening or not. Air finds a way. Protection against water in the carb is your main concern - + aerodynamics is aiding also.. My guess, is that since you have an opening on top you should have an opening on the bottom. Otherwise, it'll act like an Air Dam. Look at the cowl's on most Sport 20's like the Miss Vegas, Opening on top & Relief in back(Midway). Air flowing in - then out. Just my thought. B)

 

[Paul Traufler]

In general slow speed airflow it is best to have 2x the area for exit as you have for inlet flow. The air will get in as nature does not like a vacuum, air always wants to balance the pressure. (Yes the boat stuff is considered slow speed air flows.)

Paul

 

[gooycheese]

I was under the impression that cowls create lift. I am guessing that will really give some lift. But I will guess everything can be worked with and made to work.

 

[Tim_Duggan]

I was under the impression that cowls create lift. I am guessing that will really give some lift. But I will guess everything can be worked with and made to work.

Some can, because the accelerated air creates a low pressure zone. One rigger I had was perfectly behaved with no cowl, but if I put a particular cowl on it the front end ran very, very light. Many cowls can have the opposite effect and create downforce.

 

[misshydro]

lol @ scale cowl on that rigger

nothing wrong with that,,gives it a different look..man joe is chomping at the bit to get it done for celina race..wants to get it painting this week.

 

[Blackout]

lol @ scale cowl on that rigger

nothing wrong with that,,gives it a different look..man joe is chomping at the bit to get it done for celina race..wants to get it painting this week.

I still think it's going to cause some drag and slow you down. The cowl should be no higher than the top of the engine. Any more height and you are creating more drag... Only mentioning this becuase this is your "light" race boat, correct?