Big Twin-Backlash

strictlybusiness1 replied the topic: Big Twin-Backlash

INGENIOUS!! Very clever & creative method of producing a custom cowling. I also like the addition of the carbon fiber to each hull compartment.

I have some questions, Johannes. Does the cowling have flotation? What weight carbon fiber cloth was used & how many layers were used to make the cowling? What weight carbon fiber cloth was used in the hull's compartments? Did you ever consider using .5 ounce carbon fiber matt in the compartments?

The carbon fiber cowls shown weigh between 3 & 5 ounces. They are both made with 4 layers of 6 ounce high strength carbon fiber cloth. Both contain flotation. I am sure the cowlings could be made lighter in weight if they were vacuum bagged.

Thanks for any information provided.

Jim Allen

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Hannibal replied the topic: Big Twin-Backlash

Actually I dont care about the weight of the cowl so much. Its a unique cowl so it should be really stable.
I'm using 180-200g/m2 of carbon and carbon/cevlar fibre and I have used about 5 layers. So its pretty stable.
The cowl does have 2 floatatios. You can see it in the first video.
For the sponsons i was using same carbon fibre, for the whole hull partly in combination with carbon/cevlar fibre.

Johannes
#24057
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strictlybusiness1 replied the topic: Big Twin-Backlash

Thanks for the answers. 180-200 g/m2 is approximately 7 ounces/ sq yard so that is the same weight I use. The Kevlar is a good idea because it will give the carbon fiber very high tear resistance.

JA
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Rysquedases replied the topic: Big Twin-Backlash

Great work taking it to the next level. I haven't lost a shaft yet be I'll give that wire behind the prop nut a shot.

Thanks for sharing, allways nice to see what comes from someone's creativity.
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strictlybusiness1 replied the topic: Big Twin-Backlash

There is another system that prevents propeller loss, no matter where the cable breaks, from the cable shaft joint up to the engine collet. The first photo shows a complete cable, propeller shaft, bushing, drive dog & lock nut. A soft soldered, in place, brass sleeve (.250" ID X .2812" OD X 1.500" long), which reinforces the flex cable propeller shaft joint CANNOT PASS THROUGH the machined bushing (.250" ID X .375" OD X 1.375" long) in the event of cable breakage occurring at any point before the brass sleeve. The brass sleeve rotates freely inside the already existing stuffing tube adding to the length of the bearing surface. The propeller shaft bushing is a slip fit into the strut & is held in place with a 3-48 screw. The bushing is precision machined from B-10 grade Bearium Bearing Bronze. It is unaffected by the propeller's radial load & the propeller shaft's RPM, therefore it lasts indefinitely.

Another part of this system, which eliminates repeated removal of the cable to facilitate lubricating the cable, is the grease fitting & Teflon sealed rubber boot at the upper end of the double walled stuffing tube. A small grease gun & Lubriplate Special Marine Grease #2 gives a very low drag lubricating system. A small amount of grease is pumped into the stuffing tube before each run, making removal of the cable un-necessary, since the grease always moves down the stuffing tube, towards the strut! Notice the water inlet on the bottom of the strut which provides water lubrication.

Jim Allen

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Hannibal replied the topic: Big Twin-Backlash

Yes your propeller shaft joint looks interesting. I'm also still looking for a durable and "easy to maintain" solution.
So far I'm doing some experiments by using prop shafts with deep drilled 0.125" holes to have an increased surface for the glue/solder (depth of the hole: 1 3/4"). So I'm not using an additional brass sleeve to connect cable and shaft. Outer diameter of my prop shaft is about 0.315". (…most of german powerboat drivers using 0.315" prop shafts, after dog drive reduced to 0.125" for the propeller, of course)

Example:


So I'm still searching for some good ideas to make sure not to loose the cable anymore. My current solution is okay but doesn't look very nice. Let's investigate a little bit to get perfect solution!
Looking forward, guys!

Greetings
Johannes
#24082

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strictlybusiness1 replied the topic: Big Twin-Backlash

Good stuff Hannibal, which is easy to do & makes the hull's mechanical parts reliable! My drive shaft is hardened & spring tempered. The area underneath the brass tube is spotted in many places to give the solder a better place to adhere to. I forgot to mention the oil hole in the side of the strut that lines up with the second hole in the bushing. I lubricate the bushing area with a high pressure oiler before each test run. I also use a cone point, internally splined set screw, with a matching cone shaped cavity in the shaft in place of the standard hex set screw. The internally splined (Bristol) type set screw can survive under severe tightening. The set screws have machined cone shaped points that sit into matching cone point cavities in their shafts. No silly type flats or double set screws are ever used. The # 271 Loctite used will require heat to remove the set screw. The set screw can be used indefinitely.

Are the three pieces before your drive dog some type of thrust bearing? Please explain further? I am presently driving the thrust up the shaft into the engines bearings. I believe this causes even greater friction & heat in the stuffing tube. However, this has no effect on the engines radial ball bearings.

Jim Allen



#24084
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Hannibal replied the topic: Big Twin-Backlash

Hello guys,

she is getting faster! :)



Greetings
Johannes
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Canadian Hot Rod RC Boats replied the topic: Big Twin-Backlash

Very nice
Randy

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#25406

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BIGJACK9170 replied the topic: Big Twin-Backlash

Rather than extremely over engineering a 1 off part lol just use a good shaft saver !
CC racing has some great bolt style savers and they work flawlessly . They have a stainless steel bolt so that's a big plus!! I've used them for 3 or 4 years now and haven't ever lost a shaft or prop . If it makes you feel better use 2 of the savers if you have room . As far as green , red, blue locktight I use red as you can remove the set screws with standard tools .
I've seen some wild engineering parts that just are totally unnecessary . The 99% guys that " RACE" all year use regular parts that have been proven to work year after year so if it's good enough for these guys it's sures hell good enough for me and the rest of the world lolo.
Good luck and your BEASTLASH is one bad a$$ ride !!

www.ccracingengines.com/index....ategory=4230731


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