So how much thrust do we loose by bending the jetstream with a droop snoot or a severe angle change with a place diverter?? A well respected engineer once gave me a lesson on this, but I seem to have forgotten some of it. I do remember that there were significant losses from bending the water, but I dont recall those numbers. At the time I was adding a large amount of down wedge behind my droop to keep the nose of the boat down and he was telling me how much thrust or velocity you loose per degree of wedge.Anyone know?
Ive been kicking around the idea of trying some different configurations to limit the amount of "bending".
Here is what I am currently running..AMT droop w/ a berk. R nozzle. Notice how the droop makes a radical turn just past the outlet of the bowl.
http://www.***boat.com/image_center/...09shop_011.jpg
This configuration below is an HTP snoot,custom aluminum spacer, wedge and place diverter.
Now with this set up below there is alot less bending, but the pump is a mile long. What I was concerned about was loosing lift due to the thrust line not being as low as it was with the set up above, but after some careful measuring, the thrust line is only 3/8" higher than it was with the set up above and there is alot less "bending".All thrust line measurements were taken with identical nozzle angles, so everything was the same.It appears there is still some bending going on due to the 4 degree wedge (which i need to get the thrust line down lower) and there is a very small amount of bending at the diverter to get my nozzle angle where I need it to be, but its minimal.
Is limiting the "bending" worth going after?
CS
http://www.***boat.com/image_center/...09shop_010.jpg
CS, can't you achive enough lift usung a Backcut shoe? Thats ultimately where your riding surface is, no? Bending the water once, and rotating the whole mass thru the bowl, and then bending it again. Is there a point, where a tunnel gets too much lift at the back? This is rocket science :rollside:
Sleek
CS, can't you achive enough lift usung a Backcut shoe? Thats ultimately where your riding surface is, no? This is rocket science :rollside:
Sleek
my personal belief is no you cant.
http://www.***boat.com/image_center/...09shop_010.jpg
Just turn that whole mess upsidedown and you'll be going down the course like a TFH. :skull: I remember that pic of MikeC in Phoenix. :rollside:
There is probably something there. But all the extra surface area might cause some extra drag too (albiet, minimal). I'd be a little more concerned about the running angle of the diverter. If angled up or down a little, it makes the passage (diameter) smaller.
The diverter is almost dead nuts straight. The wedge lands the nozzle almost at the perfect angle.A very minor movement of the diverter is needed.Less than .5 of a degree.
I do like the smoother flow, using the snoot, and wedge method, to achive your discharge height. One other questoion, is your leverage point is moving aft, as a result of a longer strait snoot, you may also derive better lift from leverage.
Sleek
I would hope the boat is fully up on the plate at speed.All the crap off the back is about 2.5 inches above the plate,but yes its definatly a concern.It might be a good trade off, a little extra drag, but more thrust?
I would say yes, that limiting the "bending" is definatly worth going after!
I really don't understand your reasoning for wanting your thrust line down so far though. I'm sure you have a reason, but it's just not apparant to me.
Possibly necessary to keep your flow through the nozzle straight with the snoot?
Ken F
I do like the smoother flow, using the snoot, and wedge method, to achive your discharge height. One other questoion, is your leverage point is moving aft, as a result of a longer strait snoot, you may also derive better lift from leverage.
Sleek
i agree.
I would say yes, that limiting the "bending" is definatly worth going after!
I really don't understand your reasoning for wanting your thrust line down so far though. I'm sure you have a reason, but it's just not apparant to me.
Possibly necessary to keep your flow through the nozzle straight with the snoot?
I'm with you on the backcut shoe too, although you definatly can achieve lift with one- just need to be really careful at the speeds you are running.
Ken F
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