MAC.84\CF Rigger

[MikeP]

Hey Mike,

When you make those sheets you need to be able to see the peelply through the bag. You can see the dry spots, I use a small 1" roller for wall paper and work from the center out as the vacume is applied and make sure all the peel ply is wet. To do that I lay cloth then peelply then mylar. No breather cloth. Those 3 layer sheets work good glued to foam. It takes about 2 weeks for the epoxy to get really get hard.

I am thinking you will need 8 layers on your hull.

Did you see the sponson blue prints that hammer posted? that is what he sent me, I used them with some adjustments to fit.

-MikeP

 

[MikeP]

Trying to wrap things up in the hull today and get started on the cowling, it's my favorite part. I finished the servo trays, finsihed the motor mount doublers so I could firmly bolt the motor in, and finally line up the bulkhead and the stuffing box tube, followed by the servo trays.

http://69.27.9.16/mikep/cf90/servotray.jpg

http://69.27.9.16/mikep/cf90/doublers.jpg

http://69.27.9.16/mikep/cf90/servotub.jpg

-MikeP

 

[MikeP]

I found a good use for all that extra plywood I have. I can also use up some of that Hobby shop epoxy I have sitting around. It works good for molds. It's good to get my hands into some wood.

http://69.27.9.16/mikep/cf90/cowl1.jpg

http://69.27.9.16/mikep/cf90/cowl2.jpg

http://69.27.9.16/mikep/cf90/cowl3.jpg

http://69.27.9.16/mikep/cf90/cowl4.jpg

http://69.27.9.16/mikep/cf90/cowl5.jpg

http://69.27.9.16/mikep/cf90/cowl6.jpg

-MikeP

 

[MikeP]

Here are some pictures finishing up the plug and finishing the mold for the cowl.

http://69.27.9.16/mikep/cf90/cowl7.jpg

http://69.27.9.16/mikep/cf90/cowl8.jpg

http://69.27.9.16/mikep/cf90/cowl9.jpg

While the cowl mold was setting up I did some work on the OS 9b carb. I wanted to smooth out the intake behind the carb so I made a little spacer the matches the carb diameter on one side and the engine diameter on the other.

http://69.27.9.16/mikep/cf90/carb1.jpg

http://69.27.9.16/mikep/cf90/carb2.jpg

http://69.27.9.16/mikep/cf90/carb3.jpg

I also like the bellmouths so I made a piece to hold the carb and pressed it into the back side to chuck it up. I made the bellmouth out of black delron and pressed it onto the intake.

http://69.27.9.16/mikep/cf90/carb4.jpg

http://69.27.9.16/mikep/cf90/carb6.jpg

http://69.27.9.16/mikep/cf90/carb7.jpg

-MikeP

 

[Twin_k90]

Mike,

Im just starting to get into the world of Vac bagging, i need to do my sponsons i have the mould etc already,

what type of bags do you use?? do you use special vag bagging bags? of just normal clear plastic??

Dale

 

[MikeP]

Dale,

I use a vacume bag made for vacume bagging. It is a tube and I can seal each end with a quick lock plastic thing. I have heard of others using what ever they can get there hands on and use sealing tape to seal the edges. You have to use the sealing tape if the project is too big for the bag. The nylon bagging material, fittings and quick lock seals are to cheap not to use them. I am still using the original bags I started with. He is a picture of one.

http://69.27.9.16/mikep/cf90/bag.jpg

-MikeP

 

[MikeP]

Ok, need some ideas here, I finished the cowl mold and made a cowl. I got it cut out around the motor and pipe. How much air flow does it need through it?

http://69.27.9.16/mikep/cf90/cowl11.jpg

http://69.27.9.16/mikep/cf90/cowl10.jpg

Thanks

-MikeP

 

[Ian Inverarity]

Mike,

The general rule of thumb on inlet and outlet areas is to make the outlet at least 1/3 larger in area than the inlet to allow for the expansion of the air due to heating.

But I didn't get that scientific when I cut the canopy for my 90 rigger. The outlet area around the pipe is probably larger than I needed, but I like to have a bit of flow around the header to preserve the silicone better.

Here is a picture of the boat, with the cowl not pushed all the way down. These cutouts seem to work okay for me.

http://members.dodo.com.au/ozzy1/images/20...icture_0100.jpg

Ian.

 

[Twin_k90]

Dale,

I use a vacume bag made for vacume bagging. It is a tube and I can seal each end with a quick lock plastic thing. I have heard of others using what ever they can get there hands on and use sealing tape to seal the edges. You have to use the sealing tape if the project is too big for the bag. The nylon bagging material, fittings and quick lock seals are to cheap not to use them. I am still using the original bags I started with. He is a picture of one.

www.ad.kengarff.com/mikep/cf90/bag.jpg

-MikeP

Thanks Mike,

where do you get all your stuff from, i went to the glass shop and spent over $350au on stuff last night!!

damm

Dale

 

[Ian Inverarity]

Dale,

Maybe try contacting these guys:

http://www.advcomposites.com.au/prod02.htm

Ian.

 

[Twin_k90]

ian,

the problem there is the price!!! clear plastic from the hardware store is about a 1000th the cost!!

Dale

 

[TimD]

Mike P,

Air flow is good - water injestion is bad! Make sure any vents you put in are behind the carb. I like the "gill" type of vents - thin diagonal vents parrallel to each other.

Also, keep in mind that the header area of the pipe is the hottest part under the cowl so allow plenty of room for air to exit.

Tim.

P.S Boat is looking very stealth like! 8)

 

[Ian Inverarity]

Tim,

It may not be clear from that picture of my boat but those inlets are actually behind the carb opening. I have not run thru a rooster tail to test it yet, and dont intend to either! ;D

Dale,

The film may need to be 'stretchy' to go into complex shapes like a cowl or sponsons. Try the hardware store film, but I think it may wrinkle a bit much!

Ian.

 

[Twin_k90]

Ian,

Taryns dad has got me some plastic, still a little streachy, the thinner the plastic the more it will wrinkle, this stuff should be good, and i can get a 100m roll of it pretty cheap.,

ill play around and see how we go!!

Dale

 

[MikeP]

I get all my vacume bagging stuff except for the CF cloth from this place. 5yards of nylon bagging film is $6.50us

If you use peelply and breather cloth wrinkles in the bag won't make a difference. I tried a thin plastic film in side the bag directly on the epoxy and it was a mess. The bag has to be able to slip and slide as it forms over the mold.

http://www.acp-composites.com/ACP-CAT.HTM

I doesn't sound like I need HUGE air intake holes, thanks for the input. I think a couple of scoops on each side will be ok, with a good opening around the pipe.

-MikeP

 

[Ian Inverarity]

Mike,

If you put scoops I think you will definately get water coming in! If you just cut slots or vents in the side, air (which is much thinner than water!) can be drawn in but water has a hard time changing direction fast enough to get into the holes cut on the side. That is how I think of it anyway....

Ian.

 

[TimD]

Mike,

These are the kind of inlets I like - Paul "ozzy" Osmonds boats have them. http://members.dodo.com.au/ozzy1/images/My...icture_0074.jpg

 

[Twin_k90]

Mike

thats for the site!

I dont use any air holes in my cowls, i havent had any not enough air problems yet,

Dale

 

[TimD]

thats because of all the oil from your exhaust throttles is keeping the motor cool HA HA HA

 

[Twin_k90]

tim,

yes the oil keeps everything well lubed!! i have to take them off and get them back to the man that made them as well!!