Carbon Fiber Catamaran with an adjustable CG & adjustable turn fin

[Jim Allen]

Hi Mike,

Since 2013 I have used only Evinrude Johnson OMC #0582508 coils in place of the standard gray coils. Plug gaps are set at .018" to .020". These coils weigh approximately 8 ounces & require very good ground straps & plug wire connections.

Jim Allen

 

[Mike Byer]

How long has it been since we ran together? I don't remember seeing that coil. I've used several other coils, all have started and ran better than the oe.
thanks,
mb

 

[Jim Allen]

How long has it been since we ran together? I don't remember seeing that coil. I've used several other coils, all have started and ran better than the oe.
thanks,
mb

I looked in my log & it looks like 2013 was the last time we ran at the Piedmont Triad site. I tested other coils & a power spark system on my dyno. This particular coil is the only thing that would fire the custom made surface discharge type spark plugs. I also have a note where I ran a plug gap of .025" on NGK CMR7H plugs with this coil.

Jim Allen

 

[Jim Allen]

I decided to change the trim tab servos to Hitec D956WP's. They can be purchased with clockwise or counter clockwise rotation, which means the servos will be facing in the same direction. The set up plate & drill jig shown will allow the trim tabs plus their actuation rod positions to easily be located on the angled sponson rear surfaces. I also machined new throttle arms that lock positively on the .190" OD butterfly shaft.

Jim Allen

 

[Jim Allen]

I have begun to set up the tooling for the radio controlled trim tabs. My radio can be programed to have them operate automatically any time I use the rudder or they can operate independently. Either way, both tabs will go down the same amount at the same time. The black angled shims (3 deg) will set the trim tabs to the same angle as the sponson bottoms. They also set the correct depth for trim tabs from the sponson bottoms. I probably will make a new drill jig which will be clamped to the base plate as shown in the photos.

Jim Allen

 

[Jim Allen]

I finally decided on the position & method to mount the trim tab servos. The final position is setting as low as possible, 1/8" away from the bottom inside of the sponson bottoms & as close to the hulls balance point as possible. A solid type mounting system would have definitely been easier. However, the clockwise, counterclockwise rotation of the Hitec D956WP servos used allows for the easy mirror machining of right hand side & left hand side mounting systems. A total of 4 duplicate machined pieces make up each side, including the G-10 fiberglass base plates. The servos are shock mounted with the molded grommets provided. Next will come the direct linkages to the trim tabs.



Jim Allen

 

[Terry Keeley]

Sweet!

 

[Jim Allen]

The simple drill jig shown allows for the precise location of the holes in both sides of the transom. The two holes are not only precisely located but they are at the correct angles for the brass tubes which hold the rubber sealing boots that are used outside & inside of the transom wall. I use an end mill mounted in a drill chuck, turned by hand, to cut the holes through the thick carbon fiber transom. Notice how the 5/32" piano wire rod lines up perfectly on the right hand side.

The last two photos show how the drill jig is used to hold the brass rubber seal mounting tubes for glueing inside the uneven transom surfaces. They will also be glued with a doubler block on the outside.

Jim Allen

 

[Julio Almazan]

Nice job...
Very good work... really very well explained

 

[Jim Allen]

The same drill jig is used again to securely hold in place the brass rubber seal mounting tubes & the 1/8" thick carbon fiber doubler piece on the outside of the transoms. An additional brass tube with a clamp ring sets the depth of each seal mounting tube. A white machined teflon sleeve is placed inside the mounting tube along with the 5/32" rod that is connected to the servo to ensure the alignment is correct. The angled hole in the doubler piece fits tightly on the brass seal mounting tube. Clamping of all the pieces involved ensures perfect alignment until the J-B Kwik weld cures.

Jim Allen

 

[Jim Allen]

The trim tabs are now complete except for the two simple machined pieces that attach the trim tabs to their 5/32" piano wire actuation rods. The trim tabs were machined & then carefully bent to match the angle of the sponson's rear surfaces. The trim tabs are set at the correct angle & depth with the wedges shown. Mounting the trim tabs to there 3/16" thick carbon fiber bases, with the grommets & hardware to be used, & then glueing these entire assemblies, guaranteed their exact location. The same hardware mounting base plate was used again. No holes were drilled through the boats sponson's rears surfaces! Testing the movement that the grommets would allow, before mounting, showed a movement of approximately 1/4" up or down with very little force being applied. I can't wait to test the things out!

Jim Allen

 

[Jim Allen]

I will be setting up & testing a 3 mm (.1181") piano wire drive that is an exact copy of the the type used by Ed Kalfus in his record setting tether boats. He fully developed this technology in 1937 & 38 using ready available K & S piano wire which is still available in most hobby shops. The same type & size , precision ground "single split" collet assemblies, were used to effectively clamp 3 mm, 1/8", 3/16", 1/4" solid, as well as flexible 1/4" cable drives. I will be making a comparison between the 1/4" flexible cable & the 3mm piano wire drive with a set up that will be interchangeable at the lake site. The photos show how some 1/4" size hardened & ground, precision single split collets, were easily made. This type of single split collet mounted in its hardened & ground clamping body, with a 32 pitch OD thread, never wears out & it will maintain its precision forever! Notice the machined spring steel thrust washers which allow severe tightening of the 32 pitch ID clamping nut against the collet.

Jim Allen

 

[Jim Allen]

I used a slightly different method to set up the actuation rods for the trim tabs. 5/32" piano wire is still used, but the 4-40 hardened stainless steel ends are press fitted & glued with # 648 Loctite instead of being soldered. Four faceted carbide drills are used to drill a .110" diameter hole 5/8' deep in the piano wire. This is much easier to do than soldering.

Jim Allen

 

[Jim Allen]

The trim tabs with all their associated parts & linkages have finally been completed. I have not set the maximum downward movement amount as yet, however the last two photos show what could be expected. The two D956WP servos easily raise the entire rear end of the boat off the building fixture with very little effort. I used the same 5/32" OD piano wire rods with a .375" x .750" X 1.5" long aluminum interconnecting block which made any rod length adjustments a "piece of cake". The 5/32" piano wire rods have 5/16" long flats milled where the 8-32 set screws lock up.

Jim Allen

 

[Jim Allen]

I machined these two 1/8" thick carbon fiber supports to eliminate the possibility of cracking the carbon fiber deck where there are no bulkheads. The two pieces weigh a total of 1.5 ounces. They are very rigid & provide a support distance of 8" under the deck cowl 0pening.

Jim Allen

 

[Jim Allen]

Since I always use a tuned pipe pressurized fuel system, no bladder of any kind can be used. The 12 oz. main tank & the 4 oz. secondary tank both have custom removable mounts. The tuned pipe fits into the engine's header with a labyrinth type seal. There is no straight section inside the tuned pipe or the header section at this critical transition point. A teflon sleeve will be added to make this joint 100% air tight!

Jim Allen

 

[Jim Allen]

3" OD pool noodles are used for flotation after their ends were sealed with Goop. I used Nokorode Black Silver Soldering Flux & Aufhauser Silver Alloy 45 (1370* F - 1550* F) for the tuned pipe pressure fittings, any tuned pipe joints & 1/8" of the cable's end that goes into the collet. The aluminum heat sink fixture prevents any heat from traveling past its end point. Silver soldering the cables end eliminates uwinding problems. This same heat sink will be clamped approximately 1.250" from the cables end. Lucas-Milhaupt 400* F solder with Lucas-Milhaupt Tec Flux is used to make the entire 1.250" end of the cable a solid.

Jim Allen

 

[Rick Doane]

Hello Jim:

I am interested if you have been able to try your adjustable trim tabs to date? Thank you for all the great information.

Regards...........Rick

 

[Jim Allen]

Hi Rick,

The trim tabs work perfectly as described by the Australian model boaters. The horizontal movement of the right side stick, with the mixer function off, only moves the rudder to the right & left. Any downward or upward movement of this stick, with the mixer function off, activates both trim tab servos. It is also possible to program the Tx so that the trim tab servos are slaved to the rudder servo movements. I have not tested this as yet. The downward movement is presently set for a maximum movement of 5/32" & the upward movement of 3/64" using the building board to measure both sides accurately. The two adjustment blocks make it easy to set both sides to the same amount of movement.

Jim Allen

 

[Jim Allen]

Rick,

Here are some photos of typical setups used on cats & V bottom hulls. Both use one servo with linkages.

JA