Gas Lobster Boat Losing Speed In The Turns

[Wesleys Custom Graphics]

The reason I use the #8 lead shot is because it's so small and you can get it all the way up in the tips of the sponsons without any dead space. Do the best you can to get that CG closer to the vertical centerline of the turn fin.

On my way to the lead store now. We'll see what happens.

I buy my lead shot at the local gun shop, very popular size for shotgun shell loading.

Went to the gun shop and they said they dont carry lead any more. Went to the hobby shop and they said they cant get lead any more. Some kind of obama restriction on lead. What the heck?

 

[Don Ferrette]

The reason I use the #8 lead shot is because it's so small and you can get it all the way up in the tips of the sponsons without any dead space. Do the best you can to get that CG closer to the vertical centerline of the turn fin.

On my way to the lead store now. We'll see what happens.

I buy my lead shot at the local gun shop, very popular size for shotgun shell loading.

Went to the gun shop and they said they dont carry lead any more. Went to the hobby shop and they said they cant get lead any more. Some kind of obama restriction on lead. What the heck?

Really???? Well here's a place - http://www.rotometals.com/product-p/lead_shot_magnum_25.htm

 

[Tim Strange]

Yeah lead is tough to find these days...and it's pretty expensive now. The last U.S.lead smelting facility was closed last year by the EPA. Kind of hurts ammunition production.

 

[El Zorro]

You can get a jar of BB's at Walmart. I use to make up one, two and five pound weights for the big boat using BB's tied up in a 20 inch bicycle inner tubes. The lead shot is probably cheaper, though.

Dick Tyndall

 

[SayMikey]

I have a cool whip tub thats full from my karting days

 

[Tim Strange]

Just thought of this, try Wal-Mart or any fishing supply place for lead sinkers. The largest I found locally were packages of 3-5 large 2-2.5 ounce weights. Since lead is malleable, you could hammer them to a usable shape. I'm thinking flat for your situation, and you may need to bolt the pieces in...

 

[wayne middlemiss]

Same in Aussie all steel shot no lead no more unless you can get a shot maker to make your own lead shot.

 

[Wesleys Custom Graphics]

Found a couple of bags of those little led sinker weights at wally world.

 

[Don Ferrette]

The main reason I recommended the #8 lead shot is at a diameter of only .080" you maximize the amount of weight in a given area with no "dead space" between lead pieces. Those little pieces of shot will pack into every little open crevice making for very dense ballast all the way into the sponson tips. You might want to see how far you can cut those sinkers down to, the smaller the pieces the better.

 

[Wesleys Custom Graphics]

The main reason I recommended the #8 lead shot is at a diameter of only .080" you maximize the amount of weight in a given area with no "dead space" between lead pieces. Those little pieces of shot will pack into every little open crevice making for very dense ballast all the way into the sponson tips. You might want to see

how far you can cut those sinkers down to, the smaller the pieces the better.

I put about 3/4 lb of sticks on the tips and only got the cg forward maybe 3/4 of an inch. I guess I will start with that. Maybe I can adjust the canard wing a bit to compensate.

 

[Don Ferrette]

Was that 3/4 total or 3/4lb each side? Also what are the rear wings made of? The afterplane on the lobster is so flippin' long that wing weight becomes ulta critical. I have shaved over a pound of wing weight on an 1/8th scale before going from 'glass to solid balsa with a .5oz layer of 'glass cloth covering. You'd be surprised how strong that balsa becomes with that thin layer of cloth over it.

 

[jeffaustin]

I have been making rear wings out of solid balsa and epoxy after watching Greg Hahns video,they are extremely light.take your wings off and see how much your CG changes,if you want a set of wings let me know

 

[Wesleys Custom Graphics]

Was that 3/4 total or 3/4lb each side? Also what are the rear wings made of? The afterplane on the lobster is so flippin' long that wing weight becomes ulta critical. I have shaved over a pound of wing weight on an 1/8th scale before going from 'glass to solid balsa with a .5oz layer of 'glass cloth covering. You'd be surprised how strong that balsa becomes with that thin layer of cloth over it.

Actually, I am considering that. I made the wings out of 3mm extruded pvc. It is light weight, strong and it floats. I took a hard roll at evansville trying to mis a boat that fell off the pipe in front of me. The control horn broke as well as bending the brace but the wings held up. That said they are heavier than glass reinforced balsa. I guess I could make 2 or 3 sets. That was 3/4 total stick weights. I got 2 lbs of shot and that puts the cg right on the turn fin. You want to b a little behind it right?

 

[Don Ferrette]

Was that 3/4 total or 3/4lb each side? Also what are the rear wings made of? The afterplane on the lobster is so flippin' long that wing weight becomes ulta critical. I have shaved over a pound of wing weight on an 1/8th scale before going from 'glass to solid balsa with a .5oz layer of 'glass cloth covering. You'd be surprised how strong that balsa becomes with that thin layer of cloth over it.

Actually, I am considering that. I made the wings out of 3mm extruded pvc. It is light weight, strong and it floats. I took a hard roll at evansville trying to mis a boat that fell off the pipe in front of me. The control horn broke as well as bending the brace but the wings held up. That said they are heavier than glass reinforced balsa. I guess I could make 2 or 3 sets. That was 3/4 total stick weights. I got 2 lbs of shot and that puts the cg right on the turn fin. You want to b a little behind it right?

If you are using Tyndall's bracket as well as fin CG between 1.5" to 2" behind sponson transom should put it right on the vertical centerline of the fin.

 

[Wesleys Custom Graphics]

Well the lead helped but not like I thought it would. It made it more stable and that made the fin plant better thus helping. I can hear the prop air out a little in the turns now. It seems to help keep the rpms up. Overall its better but not great. I wonder if I should link the front wing to the rudder instead of the throttle. My 1/8scale is turning like a bat outa &@#$ . The wing lifts the boat when I turn right.

 

[jeffaustin]

Did you try running it without your rear wings?

 

[El Zorro]

Was that 3/4 total or 3/4lb each side? Also what are the rear wings made of? The afterplane on the lobster is so flippin' long that wing weight becomes ulta critical. I have shaved over a pound of wing weight on an 1/8th scale before going from 'glass to solid balsa with a .5oz layer of 'glass cloth covering. You'd be surprised how strong that balsa becomes with that thin layer of cloth over it.

Actually, I am considering that. I made the wings out of 3mm extruded pvc. It is light weight, strong and it floats. I took a hard roll at evansville trying to mis a boat that fell off the pipe in front of me. The control horn broke as well as bending the brace but the wings held up. That said they are heavier than glass reinforced balsa. I guess I could make 2 or 3 sets. That was 3/4 total stick weights. I got 2 lbs of shot and that puts the cg right on the turn fin. You want to b a little behind it right?

If you are using Tyndall's bracket as well as fin CG between 1.5" to 2" behind sponson transom should put it right on the vertical centerline of the fin.

Pay attention to what Don is saying in the above quote. This is where your CG needs to be! Everything you said in your last post after running the boat AFTER adding weight to the nose of the boat tells me that the boat was tail heavy and STILL is tail heavy. Don't try to compensate for an aft CG with adjustments to the boat's aerodynamics ( moving the wings or canards ). This will only cause more problems. Boats are no different than airplanes..............the Center of Gravity is very important as to how they each perform.

Dick Tyndall

 

[Patrick Mulvany]

Wes,

This is a very interesting thread since I should be getting my cowl from Phil in the mail tomorrow! YEAH!!! Paying attention to your woes and will think what is done carefully as I put it all together.. Can I ask you what engine are you running and what did you do about the Jet Exhaust Pipe??? Email me at [email protected] and let me pic your brain and compare what we have together??? I have concerns of how to fit the rear wing on??

Later!!

Pat

 

[wayne middlemiss]

I am also very interested as I am also building the lobster boat from plan in 1/6 scale but will be home for my neu 2220.

As don has said already the after plane length is an issue with the cg point .

Also from that I am building to the maximum percentage on width with more wing area to help or try to keep the boat flying in the cornering . Also the rear sponsons underneath & I have put the inner spray rails on the front for a little added extra lift up front and launching. All good knowledge thus far. Wes would like to see yours how you set it up . More pics if you will.

 

[Wesleys Custom Graphics]

Im using a rear exhaust k 30 . I have good luck with it so far. The turbin stack is 030 aluminum with brush aluminum vinyl. I got the pattern from phil thomas.

Dont get me wrong. The problems im having are minor. I can drag race with the best of em. The turns keep gettin better every time out.