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Thread: The Black Pearl P Sport Hydro 2017

  1. #211

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    Good news. The lighter V8 version is running and turning well with the 1515-1Y motor. The CG is at the front edge of the turn fin (this is key!!). It also took 6oz of weight (placed at the CG) to keep it down in race water. Speeds are 62-65mph.

    Recall that I gave up on the big motor because it was just too fast. In order to keep it down as speeds approached 70mph, it would have required much more weight at the CG. The hull was at it's speed limitations IMO. Rather than just add more weight at the CG to keep it down, I'm trying to kill some more lift to increase the speed potential. On this experimental boat, I am reducing the AOA of the kick-up at the bottom. Some previous experiments with an air dam showed the boat to be much more predictable as it gave warning prior to a blow over (floated, rather than just snapped over).
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  2. #212

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    Pete
    I got mine running at 70 with NO added weight.

    Larry
    Past NAMBA- P Mono -1 Mile Race Record holder
    Past NAMBA- P Sport -1 Mile Race Record holder
    Bump & Grind Racing Props -We Like Em Smooth & Wet

  3. #213

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    Ya know, I was having the same trouble with blow overs and after six months I found the strut had negative in it. It would cause the front to lift a little. Then the toque would pull the left a little more and over it went.
    Randy
    For ABS, Fiberglass, Carbon hulls and Stainless hardware
    BBY Racing

  4. #214

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    Quote Originally Posted by TRUCKPULL View Post
    Pete
    I got mine running at 70 with NO added weight.

    Larry
    Cool!!!! Are you coming to the MI cup? I need to see this thing! How heavy is your boat? My heavier boats were fine, but the lighter ones are requiring some added weight at the CG. I'm really starting to believe that it's better to have the weight at the CG, especially for the turns.

    Quote Originally Posted by RandyatBBY View Post
    Ya know, I was having the same trouble with blow overs and after six months I found the strut had negative in it. It would cause the front to lift a little. Then the toque would pull the left a little more and over it went.
    Oh man! That must have been a head shaker when you realized it! Definitely no negative here. My strut is dead nuts flat. Strangely enough, we did find that the rudder on the right side made it ride up the turn fin and blow off during slight left corrections. Moved it to the left side and eliminated that problem.

  5. #215

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    Quote Originally Posted by Shooter View Post
    Cool!!!! Are you coming to the MI cup? I need to see this thing! How heavy is your boat? My heavier boats were fine, but the lighter ones are requiring some added weight at the CG. I'm really starting to believe that it's better to have the weight at the CG, especially for the turns.



    Oh man! That must have been a head shaker when you realized it! Definitely no negative here. My strut is dead nuts flat. Strangely enough, we did find that the rudder on the right side made it ride up the turn fin and blow off during slight left corrections. Moved it to the left side and eliminated that problem.
    Ya it happen in a fall off the rack in the Tahoe. When I found it I thought how stupid. LOL
    Randy
    For ABS, Fiberglass, Carbon hulls and Stainless hardware
    BBY Racing

  6. #216

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    Pete

    Yes I will be at the CUP.
    My boat is one of the first one I think.
    I did build it a little heaver with all the foam in the sponsons and down the sides.
    I run 2 degrees Positive (down at the rear) for the prop that I am running.

    Do you know if anyone makes a wedge to put behind the strut mount?
    I want to cock my strut about 2 degrees to the left.
    Right now at full speed the boat wants to turn slight right.
    I have set my trim slight left to compensate, but I would like to get it fully set up with the rudder straight.

    Larry
    Past NAMBA- P Mono -1 Mile Race Record holder
    Past NAMBA- P Sport -1 Mile Race Record holder
    Bump & Grind Racing Props -We Like Em Smooth & Wet

  7. #217

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    Quote Originally Posted by Shooter View Post
    Good news. The lighter V8 version is running and turning well with the 1515-1Y motor. The CG is at the front edge of the turn fin (this is key!!). It also took 6oz of weight (placed at the CG) to keep it down in race water. Speeds are 62-65mph.

    Recall that I gave up on the big motor because it was just too fast. In order to keep it down as speeds approached 70mph, it would have required much more weight at the CG. The hull was at it's speed limitations IMO. Rather than just add more weight at the CG to keep it down, I'm trying to kill some more lift to increase the speed potential. On this experimental boat, I am reducing the AOA of the kick-up at the bottom. Some previous experiments with an air dam showed the boat to be much more predictable as it gave warning prior to a blow over (floated, rather than just snapped over).
    When I build wood hydros I now add the same weight of aluminum to the Port size as I do on the starboard side for turn fin and mount.

    I use 3/16" or 1/4" thick stock and glue it to inside bottom of sponson. The weight is well distributed and you are adding structure to the boat not just dead weight.

    >
    >

  8. #218

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    Truck pull, this is an old trick used in full sized boats for years to correct for turn fin drag and prop torque. I have seen more wedging on the rudder over the strut. I use a left side rudder to compensate prop torque and turn fin drag. It seems most modelers are seeing good results with changing the leading edge angle on the turn fin to correct steering problems. Moving the rudder under the boat can help too. Very small adjustments are advised, it's very easy to over correct. 1 degree movements should be used. Turn fin can also plant or let the right side sponson ride higher. Many options! The fun is finding out which works best on your hull and set up!

  9. #219

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    Hi everyone. I'm pretty excited about this build (Version 8.7!). I moved the motor and servo forward significantly. The more I play with these things, the more I realize that most of the weight at the CG is best, especially for turning. You don't want weight scattered all over the boat. This new design should accomplish that.

    I'm hoping to finish this to run in our September club race.

    Oh, and congrats to MI CUP champ Kenny! Black Pearl wins P-Sport 3 years in a row!!!
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  10. #220

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    Peter
    I sent you an E-Mail about COG.

    Larry
    Past NAMBA- P Mono -1 Mile Race Record holder
    Past NAMBA- P Sport -1 Mile Race Record holder
    Bump & Grind Racing Props -We Like Em Smooth & Wet

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