JAE21, Wow!!

[Jeff Schindler]

I'm wondering about the hopper tank as I have not needed it either. Are guys using those flex tanks and the fuel pickup is getting pinched in the corner of the tank? Maybe I'm not running that fast? Maybe here on our Namba course in Edmonton and Calgary we use bigger diameter corners? We typically run 300' straightaways and 90' diameter corners. 6 laps equals a mile course. I'm also running the stock fin with the edges smoothed out more than stock. Nova 5 port and woods pipe. H7 prop backcut slightly at 3.75" cup. 2200' elevation. I can hang with Alan Yuen's blackbird and some of you saw it at Hobart. Am I that slow???? More testing next year......

thanks

Alan's 'bird is fast.  I have to have the hopper tank too.  I believe the sponsons rock back and forth causing the fuel to swirl like a whirlpool but horizontally.  Its probably dynamic, not static such as G's or speed would produce.  Maybe as you go faster the dynamics of frequency response will die off.   Look at the pictures from Hobart and you will see large splashes behind the front sponsons as they alternate contact with the water.

 

[Jim Mamaril]

Well, I didnt do so well in my first race meet with the boat, but it showed good potential. My turn fin design didnt work right, I borrowed a Mike Hughes fin from Kris Flynn (thanks Kris!! B) ) and that was better. After racing we got the boat at 75mph on a Stalker radar, I was happy with that for the first hit out. I didnt have any issues with fuel pickup without using a header, in fact I was only using about half of the 10oz of fuel in each race!

I watched the video you posted and there is only one reason why your boat did what it did........."your turnfin just ain't doin' its job"........

The best fin I have personally seen on the JAE.21G2 is from David Preusse [ [email protected] ]

The stock fin from Zippkits and the Hughes fin,sharpened properly,are a close second but the Preusse fins i witnessed at Hobart were bullet-proof.

The way David Preusse sharpens his fins is spot on to the needs of the JAE21G2 handling requirements and showed

no compromise whatsoever in speed,directional control or handling......

I say again anytime you see a JAE pole vault up in the air,like in the video,the turnfin is letting the boat slide....simple as that.....

Rod , we spoke about this some time ago and I remember you noticed in some pics of my boat running that the fin was actually acting as a hydro foil and lifting the right sponson.I was having the same pole vaulting action as well. I finally sorted that out with a fin that Mike made for me but it is slightly different than his normal ones. I also found that the depth of the fin is critical in keeping it hooked up. Here is one of the pics showing the lifting of the sponson.

 

[Ian Inverarity]

The JAE.21G2 launches so easy and rides as light on the water as a waterbug.......Owners of the JAE21 are just learning to set up for those exceptional characteristics of the JAE 21.

Now I am not saying that the set-ups to do so may well not be the best overall heat race set-ups [that remains to be seen] but I can tell you this...

all the 80+ MPH passes have been made with a full blown heat race turnfin and rudder......

You have seen proof in this statement......You have been all over the mid to hi 70s without much effort of testing......Hint......Start playing with prop diameters and shorter pipes.all the while

keeping the strut down on the ski sheeting and see what you come up with......

Rod,

The current prop is 44.6mm, are you suggesting smaller? Larger? I cant get this pipe design shorter but my other pipe design is shorter, I just have to get one.

 

[Ian Inverarity]

Thanks to Murph, pic from the weekend:

http://www.pbase.com/gtmurph/image/138595335

 

[Ian Inverarity]

Thanks to Greg Moss:



I need to drive better! :blink: Even then I equalled my best heat time for 21 hydros.

 

[Tim_Duggan]

More races will see your times drop further Ian, That was a solid run for a new boat with a handling problem.

 

[Ian Inverarity]

More races will see your times drop further Ian, That was a solid run for a new boat with a handling problem.

Tim,

The handling wasnt so bad, it was more my driving! I think I may need that header tank.

 

[mike walker]

More races will see your times drop further Ian, That was a solid run for a new boat with a handling problem.

Tim,

The handling wasnt so bad, it was more my driving! I think I may need that header tank.

The biggest problem with my boats is my driving. But I thought you were looking pretty good

 

[Ian Inverarity]

I have changed my fuel tank setup to a 6oz main and a 2oz header on its side. I couldnt fit a header tank in with an 8oz tank. So far the new setup seems to work fine, I had no issues with the engine stopping.

A picture from about a month ago:

https://www.intlwaters.com/gallery/displayimage.php?album=1132&pos=4

The wake from the left front sponson is interesting! Despite no dihedral or non-trips the wakes show some water is still pushed sideways, I guess that is inevitable.

 

[moparbarn]

The JAE.21G2 launches so easy and rides as light on the water as a waterbug.......Owners of the JAE21 are just learning to set up for those exceptional characteristics of the JAE 21.

Now I am not saying that the set-ups to do so may well not be the best overall heat race set-ups [that remains to be seen] but I can tell you this...

all the 80+ MPH passes have been made with a full blown heat race turnfin and rudder......

You have seen proof in this statement......You have been all over the mid to hi 70s without much effort of testing......Hint......Start playing with prop diameters and shorter pipes.all the while

keeping the strut down on the ski sheeting and see what you come up with......

Rod,

The current prop is 44.6mm, are you suggesting smaller? Larger? I cant get this pipe design shorter but my other pipe design is shorter, I just have to get one.

not sure what rod is getting at, ian - but the 1450 i'm running & seeing high 70's to 80 mph with is 48.5 diameter with 3.75 cup. launches as easy as a tunnel & mills VERY well. running an AB billet st pipe at just under 7 7/16" on a cmb LS evo2.

 

[Ian Inverarity]

not sure what rod is getting at, ian - but the 1450 i'm running & seeing high 70's to 80 mph with is 48.5 diameter with 3.75 cup. launches as easy as a tunnel & mills VERY well. running an AB billet st pipe at just under 7 7/16" on a cmb LS evo2.

Robin, thanks. I have ordered a 1450, will mod it up to try. B)

 

[Ian Inverarity]

Well, the new 1450 worked pretty well until I crashed! :unsure:

Before that tho, fellow AMPBC club member Michael Joseph got some interesting shots including this one which shows the water curving up into the rooster tail on the side the the prop blade strikes the water:

https://www.intlwaters.com/gallery/displayimage.php?album=1132&pos=19

 

[Slideblues]

Cool pics! Hope tha crash was not to bad,

Gene

 

[Ian Inverarity]

Gene,

Unfortunately a boat stopped on the back straight, the race director didnt see it or call it, my pit man didnt see it, and I only saw it at the last moment. Then there were two dead boats on the back straight. :unsure: Mine was worse off, but is mostly hardware damage, turn fin, booms, rudder, new prop...

 

[kesso2118]

Ian,

I love the quality of the photos and the "forensic analysis", I think you owe your photographer a beer or two

 

[Ian Inverarity]

Ian,

I love the quality of the photos and the "forensic analysis", I think you owe your photographer a beer or two

James,

They are good pics, always interesting to see what is really going on rather than what we think is going on! h34r: For example the front sponsons clearly hop and spend more time out of the water than in it, but driving the boat it doesnt seem to hop at all!

Michael has health issues that means he doesnt drink, only ginger beer!

 

[mtruex]

Ian,

I love the quality of the photos and the "forensic analysis", I think you owe your photographer a beer or two

James,

They are good pics, always interesting to see what is really going on rather than what we think is going on! h34r: For example the front sponsons clearly hop and spend more time out of the water than in it, but driving the boat it doesnt seem to hop at all!

Ian,

I would say its more of a skip than a hop ;-)

Michael has health issues that means he doesnt drink, only ginger beer!

 

[Ian Inverarity]

Martin,

I agree, the sponsons are skipping! The thing is tho when I drive it I dont notice that at all, it seems like the boat is rock steady!

 

[dwilfong]

Well, the new 1450 worked pretty well until I crashed! :unsure:

Before that tho, fellow AMPBC club member Michael Joseph got some interesting shots including this one which shows the water curving up into the rooster tail on the side the the prop blade strikes the water:

http://gallery.intlw...bum=1132&pos=17

those are some great pics. I have always gone under the assumption that the front of the blade will push water around it at full speed.

These pics clearly show this going on. the leading edge pitch is the limiting factor in a blades top speed. can't go faster than the smallest pitch or you will push water. works like a brake. I have always felt that the back side profile means just as much as the front to let the water go around the prop easer.

These picks clearly show this in action.

GREAT SHOTS!

David

 

[Ian Inverarity]

David,

I will pass along you compliments to the photographer!

I'm not sure what the particular shot I linked to shows in relation to the rooster tail. Looking at the wakes made by the left sponson the water is also curving upward, essentially a wave. Now it does seem (not confirmed) that the rear sponson stays on the water, so that the wake from the rear sponson may just be a continuous version of what is seen for the front sponson. Of course evidence of prop blade strikes in this wake can also be seen in other shots, but it seems to me that the wake seen may be the result of both the rear sponson and prop. It would be interesting to get a prop only wake, that should be possible from something like a cat running the prop as surface drive with no skeg on the strut.