Balancing a 1/8 Pro Boat Miss Bud

[Foolwitools]

Hi Guys,

I've got my 1/8 Miss Bud scattered all over my project table for improvements and maintenance.

Had some problems with balance ( I think) . At 1/3 throttle it would start to tap dance on the front sponsons and get worse if I added more power. I thought I might be able to drive through it and get it up on plane, but no. the more power you add the more violent the oscillation.

I have had the following changes suggested;

Don F. suggested moving the CG forward..... I moved the battery pack, 5 sub "C" ni-cads that wieghs almost 10 oz., to the cocpit area in the nose ( my own idea) and added 8 oz. lead stick on weights to the inside of the left sponson ( suggested by Bob Kensil). No help............

Where should the CG be??

Then I added a downforce air deflector to the front wing..........No help..............

Then I ran out of time and open water.

the two suggestions I didn't get to try are;

Shim the strut to raise the transom. and / or change the angle of the rear wing.

Questions....................

I'm using the stock Prather 270 or 275 prop( I forget which it is). Is a lifting prop cure?

If I wanna change the strut angle, can I just put a washer or two under the back screws or is this the wrong way to go at this?

If I wanna change the wing angle do I want to make it so I can adjust the angle with a turn-buckle or do I just give it a couple degrees down angle and screw it in??

I'm not looking to have a competetive boat , I just want to have it run on plane at a respectable speed and handle like it should.

Thanks in advance for any help or suggestions,

Bob the Fool :blink:

 

[Hydro Junkie]

I can see a couple of problems:

1) It's still tail heavy, so a minor wing adjustment isn't going to be of much help

2) Your stick on weights are in the wrong place. They need to be as far outboard and forward as possible, so I'd recommend putting the weight on the outside deck edge of the left sponson even with or slightly forward of the front wing. One thing you need to remember is that as long as the boat has all that weight on the prop it's not going to ride very well. You need to get as much weight forward as possible so that the boat balances in the area of the skid fin.

 

[Don Ferrette]

One thing you need to remember is that as long as the boat has all that weight on the prop it's not going to ride very well. You need to get as much weight forward as possible so that the boat balances in the area of the skid fin.

H/J summed it all up right here, it needs to balance in line with the turn fin. Unfortunately unless you can get more weight off the tail she's gonna fight you. It's not uncommon for me to add a pound or more of lead in the nose of a scale to get it to balance. Contrary to what some will lead you to believe in that lighter is always better, I'll take adding a pound or more to properly balance a scale boat over an out of balance one any day.

 

[Hydro Junkie]

I couldn't agree more, though I prefer initially setting up a boat with the weight as far forward as I can get. Lighter is normally faster, but at the same time, light and poorly balanced means lots of blow overs, broken parts and repair time.

 

[Foolwitools]

so..............

I shouldn't try to change the prop thrust angle or play with the wing.. just add weight??

where should the C.G. be? Don mentioned "in line with the turn fin".. that is the rear of the sponsons... is that where I want the C.G. to be? Do I do this with the fuel tank full or empty?

It's been suggested to weight the left sponson, Why the left? do I want to put all the weight on ( or in ) the left sponson?

 

[Don Ferrette]

where should the C.G. be? Don mentioned "in line with the turn fin".. that is the rear of the sponsons... is that where I want the C.G. to be? Do I do this with the fuel tank full or empty?

I would try to get it as close to balancing on the centerline of the turn fin as possible, empty fuel tank. I tend to try to evenly split the weight added to each sponson tip of the nose. The reason I do it this way is if the boat gets loose off the water it will tend to come down more evenly as opposed to dropping the heavier sponson side but that's just my preference. If it is not an open deck hull to where you can't get to inside sponson tips & you're not afraid to, drill a couple small holes under the front canard wing big enough to pour BB's & then resin into it filling up both sponson tips. Stack weights equally on each sponson tip until it balances then use the equivalent amount of BB's poured thru the holes (while hull is standing straight up on sponson tips), pour in enough resin to lock them in place then glass closed the holes & touch up. If it is an open deck then pour the BB's & resin into the tips from the inside. The down side to this is how much weight will it take to balance? Can the motor get moved foward??

 

[Hydro Junkie]

I normally have the left sponson a little heavier to prevent(to a point) the sponson from lifting when accelerating. The reasons I suggested putting the weight on the left sponson were:

1) It's easier to adjust one side than trying to figure out both sides

2) It would hold the sponson down while you're experimenting

3) Force of habit :lol:

 

[Foolwitools]

looks like it's gonna take 3 pounds plus to make it balance............It's a big boat, but how much is too much?

and moving the engine is possible, but it will be a major project to gain less that 1".

I don't understand how this popular production made RTR that most people have a good time with could be so far out -o- wack.

I guess I'm gonna re-assemble it and buy some stick on weigths to play with when the ice goes away.

Thanks for your help and guidance,

Bob the Fool :blink:

 

[Hydro Junkie]

Actually, it's quite simple.

Pro Boat/Horizon is playing the "WOW" factor game. By selling boats based on the full sized ones(especially the Budweiser), Pro Boat/Horizon has people buying on recognition induced impulse rather than performance. There apparently wasn't much R&D time since both the small nitro and the larger gas boats are tail heavy, showing that internal layout and balance weren't high design priorities.

Now, we have beginners trying to extract more speed out of these boats, but not understanding what is happenning as the speeds increase. As Horizon fills their bank account with cash, the beginning boater is left to figure out what's wrong with their boat. Since the stock boat drags it's tail at speed, it's fairly stable. As speeds increase, the boat's poor balance starts to come into play, with sponson walking and blow overs that gets progressively worse. What makes a bad situation worse is that the boater gets frustrated and either throws the boat on a shelf or sells it and leaves the hobby

 

[larcor69]

I have been considering one of these hull's would they be legal to run in scale with a .67 engine I realize it might be a lot of work redoing the drive train with like speedmaster stuff but thought I would ask, Thanks

 

[Don Ferrette]

I have been considering one of these hull's would they be legal to run in scale with a .67 engine I realize it might be a lot of work redoing the drive train with like speedmaster stuff but thought I would ask, Thanks

Way too much needed to make it correct, not worth the hassle. I have seen one with a .67 in it & it was a real dog. Joe Warren had a real good deal on a Phil Thomas Bud T-5 with complete graphics package, Walt Barney stainless tank & Dick Tyndall turn fin for $600, don't know if it is still for sale...

 

[Foolwitools]

A new developement,

I turned the hull up-side-down to re-install the strut............ something didn't look right.

I leveled the hull bottom, mounted the strut and inserted a 12" lenght of drill rod in the bushings.

As far as I can tell with my cave man measuring tools, the strut has about 4 degrees angle that would tend to push the bow up ( is this referred to as positive angle?). I think this is part of the problem..............In fact, I remember someone having the same problem with his boat.

I made a tapered shim so the strut will have a near neutral angle. I'm assuming this will be a good thing.

right or wrong??????

Bob the Fool :blink: