eengler

Yeah, I think i'll try the lead weights.... Please give me the details paul!

Paul M

Just replied to your PM

Paul M

My advice is not secret info. Here's the PM if anyone is interested.

Take a 3 oz strip of stick-on tire weights. There will be 12 X 1/4 oz sections. I bought mine the same place I bought my last set of tires. You could also use the Great Planes lead stick on weights for airplanes. Put a strip in the tunnel (on the OUTSIDE of the hull) about 1 inch from the front. The strip will extend to within about 3/4 in of the sponson on either side. If needed you can add an additional strip 2 inches behind the first one but I would wait and see how the first one does. I only have the one on mine.

This will not only push your CG forward, it will also disrupt some of the air entering the tunnel. The guy who sells Performance Unlimited Zens has a disrupter of this type on his Falcon. He also is running in the 70's as well. There is a nice vid of his boats somewhere on RCU or Jim's Boat dock.

You basically have 2 choices. if you want to keep the boat fairly stable and run high 50's that's fine, but if you are wanting to run high 60's+ you will have to run the boat on the edge and yes there WILL be an occasional blowover. Mine will run high 60's low 70's all day long without a blowover as long as there is no wind and the water is glass. But if there is chop or breeze..... away she goes

My personal opinion is that stable boats are boring. I have no desire to go round and round at full throttle. That's why I sold my Blast Cat. I'm not a racer so I need a boat that is on the edge and requires my attention at all times.

Hope it helps

brodjack

great posting and advise paul.
Might try that trick with my falcon/Mercury cat.
Agree on the boring stable thing.All my stuff runs on the edge too and wouldnt have it any other way[8D].

Coming from flying 3D helis the drive factor has to be part of the fun..
Brod..

Paul M

Brod,

I'm surprized you fool with boats after the helis. Always used to get me watching the guys at the airplane club fly those. All that money buzzin around.... just 1 mistake from disaster. A 70 mph boat would be a little tame by comparison, I would think

Hope the tips prove to be useful

dicko

Mart there were a few cats that had these such as the Insane Gen 2 cat. The reason you don't see then anymore is that they're illegal to race. A cat is only allowed 2 contact patches & the belly pan comes into contact in the turns. so to avoid any controversy the designers/builders don't use them anymore. This is why the Gen 3 cat doesn't have one.

painman

Just finished building another mod motor and installed in falcon eariler today, hooked up to water supply and motor cranked on the first pull. Previous motor didn't have enought squish so didn't build enough power, so started over.
Added more port work along with .175" squish so after letting run just long enough to test, I shut her down, but motor sounded very strong.
Can't wait till I can get some run time on, so I can pull the trigger.
Will start running to get some break in time on motor and reseat ring.
Should be able to post some numbers by this weekend, if rain will let up; every day.

Later; Randy

martno1fan

Seems odd to me then because some of the thunderboats in the states have belly pans so id asume those are not ilegal maybe someone can clear that one up?,my understanding is its more to stop the lift created by the tunnel than to actually make contact with the water .Not saying your wrong mate .
Mart

brodjack

Any updates on the new setup randy?
We tried a home modded x467 prop last weekend,i rounded the tips and cut back the tongue,plus razor sharp.
ran extremely well,fast acceleration and good topend too.really got the revs up.
I busted it though when i tried it on my mono when i ran up a bricked bank whilst turning too fast.
I've since done the same mods to a X470 for hopefully this weekend.
I also fitted a smoother bend 105 header on the cat,hopefully might give it abit more power,worth a try maybe.
Also cut some more off the rudder,at speed these cats dont need too much rudder depth again worth a try.
Brod..

painman

Had boat out again yesterday and still running strong, and still just getting motor broke in. I will take the GPS with me this weekend and see what she has. I put the 6717/3 prop on and with the boat purring along I could pull the trigger and she would pull the nose straigth up and torque a little to one side and lay back down, so she has tons of torque and should pull the 2716 without any problems. The 2716/2 @ 15* is the fastest prop so far. I noticed that I had a head leak so had to retorque the head and I rechecked the squish and it is now at .017" even, lost a little due to the coppercoat squished out.
I will keep everyone posted as this is my first full self Mod. again thanks to Scott S.
I can also see I will have a lot of pipe tuning. Currently running a zero band pipe. I have a 2"band setting on bench but I havn't cut header yet.

Later; [sm=shades_smile.gif]
Randy

Grizzle1

In my opinion, certain things in life are impossible. The first one would be levitation without propulsion. The second would be a stock Zenoah pushing anything 60+ mph without sinking first. What is your secret? Can we get some more info on your setup? I have a full mod RCMK and I can't get over 60 with it. All done by a professional in town here.My boat is identical to yours and I'm running 6+ hp. Don't get it. Thanks for any tips you have.

Paul M

Post some pics of your set up. What pipe? What prop?

Props can be your friend or your enemy.

Ron Olson

My Feedback: (1)

Wow, did I really get behind on this thread!
Mart, belly pans got to be an interesting subject for a short time on Cat's. Insane Boats tried it with their Cat's and there was a big question about them being legal or not here in the states. If it was too low would it be considered a Tri-maran? What was funny to me is that any boat with more than one wetted surface is considered a hydroplane whether it be an OB tunnel, Cat or outrigger hydro. I think that the interpretation of the rule was that the belly pan had to be a certain height above the bottom of the sponsons. What that amount is technically, I don't know.
My Falcon now has a Scott Schneider modded RCMK in it and unless I can put a 1" header and pipe on it plus a killer prop I don't know if mine will go over 60 MPH either. It's really scootin' right now but I don't know about 60 MPH worth. 50 is no problem at all but mine has only been wet twice since the swap. The plan is to take it out again Sunday.

Body Guard

Hi Mart,
The idea of the center pod or belly pan is to lower the motor or component in the cat/tunnel hull so vertical cg can be lowered. The hull will be less likely to barrel roll in the turn if the design is good and the lowered cg will only be a help. Every little thine you put into your design should help towards a better performance. With or without the belly pan , it does not help to stop or lessen the chances of a blow over. The width of the tunnel configured to give OPTIMUM air flow for the speed you are aiming to go for, definitely play a major contributing factor. Air entrapment theory is more affected by this. Most of my tunnels, infact all of them have belly pans or center pods and if you check on the video "The Chronicle..." or on my Malaysia rc forum build thread ( http://malaysia-rc.com/index.php?topic=3515.00 ) The belly pan was not there to help take the choppy racing conditions. That handling in choppy condition is affected by the sponson design and height plus wig effect of your tunnel 'wing'.
Sincerely, hope this help to understand a little bit more about tunnel boat parts and add ons.

Rgds.

Latiff