Fighercat Cheetah 6s2p

[tiqueman]

Started filling. Will try and have it done for this weekends club test n tune

[sampit]

Great news, keep us updated on the results, looking forward to this one
Anyone thinking about buying a Cheetah dont be put off by any of this is its a fantastic handling hull anyway, just might get even better with a little extra work.

[srislash]

Started filling. Will try and have it done for this weekends club test n tune

[tiqueman]

Yes the cheetah is one of my favorite hulls....and I have a lot of boats. Those looking at getting one, don't hesitate

[tiqueman]

Just about done for a "quicki" Ill shoot it w/ paint today and get it in the water Sunday and report back.

[properchopper]

I know I promised to not post anymore about this stuff, but here's some interesting info on the theory of stepped hulls posted by Mr. Outcast on another forum. It is in reference to full-sized boats and as such doesn't always translate perfectly to scale stuff, but :

Stepped%2520Hulls-%2520Feb07[1].txt

For no particular reason, I'll quote the late British scientist J.B.S. Haldane's take on theory acceptance :


" Theories have FOUR stages of acceptance -

1. This is worthless nonsence

2. This is an interesting but perverse point of view

3. This is true but quite unimportant

4. I always said so

[monojeff]

To me it seams the last ride pad is stepped down because when on plane there is less area touching the water so it seams as though they wanted to keep as much of the ride pad off the water as possible to keep the least amount of drag possible.
Instead of showing the ruler flat on the step you should show it at ride attitude where the waterline would be see where that puts things.
Picture water coming over the last 2 steps you would want both to barely touch the water instead of just 1 to give it a little larger foot print is my take.
You would also not want the last step to be completely touching and dragging which is what I think would happen if it were the same plane ad the 2nd step.....

So its kinda like a recovery pad of sorts......

Then when you come off plane the boat would be on 2 steps instead of just the 1 and when not on plane the boat tilts back on the last pad to help it get on step.

When at full tilt almost nothing is touching the water just like hydros so its the times when you slow down or turn that really makes a boat look fast if it handles well during these times when running.

Then again I am still learning!!
If only we knew who designed the boat we could ask them!

[tiqueman]

At ride attitude it would be severly negative, which is what it is, which is why my boat keeps going under water at 50+ mph.. No worries. Im gunna prove my point in 48 hours. Ill bet all my boats on it. No way that the last ride surface can be that negative compared to the other two and not have a bow down effect. Its acting EXACTLY how what tony posted is explained as a trim tab, angling down. Its extremely simple physics. If it was to lessen the surface area on the last pad, they should have made the indentation of the step two inches longer and keep the ride pad "level" or at ride attitude. It doessnt matter where ride attitude is. it attitude is whatever the hull is telling it to do? If the last wetted surface is at a negative or down angle, its going to put the bow down. For ALL of you non believers, change the trim tab on a mono. Lastly when the manufacturere agrees they messed up..... nuff said So yes Jeff, we DO nkow who made it and I have discussed it with them..... 7 weeks ago.

[properchopper]

To me it seams the last ride pad is stepped down because when on plane there is less area touching the water so it seams as though they wanted to keep as much of the ride pad off the water as possible to keep the least amount of drag possible.
Instead of showing the ruler flat on the step you should show it at ride attitude where the waterline would be see where that puts things.
Picture water coming over the last 2 steps you would want both to barely touch the water instead of just 1 to give it a little larger foot print is my take.
You would also not want the last step to be completely touching and dragging which is what I think would happen if it were the same plane ad the 2nd step.....

So its kinda like a recovery pad of sorts......

Then when you come off plane the boat would be on 2 steps instead of just the 1 and when not on plane the boat tilts back on the last pad to help it get on step.

When at full tilt almost nothing is touching the water just like hydros so its the times when you slow down or turn that really makes a boat look fast if it handles well during these times when running.

Then again I am still learning!!


If only we knew who designed the boat we could ask them!

(ignore the subtitles - it's actually a sponson-designing think session)

http://www.youtube.com/watch?v=ybHujsf1GGc

[tiqueman]

To me it seams the last ride pad is stepped down because when on plane there is less area touching the water so it seams as though they wanted to keep as much of the ride pad off the water as possible to keep the least amount of drag possible.
Instead of showing the ruler flat on the step you should show it at ride attitude where the waterline would be see where that puts things.
Picture water coming over the last 2 steps you would want both to barely touch the water instead of just 1 to give it a little larger foot print is my take.
You would also not want the last step to be completely touching and dragging which is what I think would happen if it were the same plane ad the 2nd step.....

So its kinda like a recovery pad of sorts......

Then when you come off plane the boat would be on 2 steps instead of just the 1 and when not on plane the boat tilts back on the last pad to help it get on step.

When at full tilt almost nothing is touching the water just like hydros so its the times when you slow down or turn that really makes a boat look fast if it handles well during these times when running.

Then again I am still learning!!
If only we knew who designed the boat we could ask them!

And cats arent made to run like 3 point hydros. If that was the case, why are all the best running stepped cat hulls, be it some only in a straight line, Geico, HOTR, Rivercat, EKOS, HPR, Genesis etc etc.. NONE have the last step 3 degrees negative than the others. NONE

[tiqueman]

Im done watching and reading. Ill be back after I run mine and thatll be the end of it. This is a waste of time. I have things Ive got to do. I need to call seastar, teleflex etc and tell them to stop making trim tabs... negative angles dont effect bow ride.....

[monojeff]

I have hardly even looked at the bottom of the boat aside from pics on here.
To me it seams the straight edge is not touching the last step??

Just don't see how if it is lower then the other step then it would raise the bow not cause it to drop??
Maybe I am seeing it wrong.

Raise your strut bow up lower your strut bow down....?

[tiqueman]

To catch you up jeff. Im not doing it to try and make the bow ride high because i want it to float more. Im doing it because the boat plows like a tug boat. Like a .. here come the broken record, mono with the trim tabs way down. Its literally pushing the transom out of the water, which in all my years of boating, forces the bow down. Yes, there are ways around it, adjusting this and that to get around hull running issues, but you cant just raise the strut on a twin drive. at least, not easily All I did was match the ride surface of the last step to that of the one before, which matched the front sponson coming into the forward most step. im not trying to re-invent the wheel.. just fixing a flat.

the "before' pis, I had a 3' construction angle on it and it was way past the teatering edge of the bottom profile so it was leaning slightly nose heavy if you will. if I push it down it would only touch the very rear of the boat while against the sponson coming in and forward most steps.... If that makes sense.

[RCKong]

I've been following this 6s cheetah thread ( I have one) and I agree the angle on the last step is acting like a trim tab. I would imagine it creates a bit of drag too. I was amazed to see what it took to air this boat out good. In my twin I had to trim the drives three times to get it to lift the nose, twice the angle of several other boats I have, and it still rides very flat. I kinda wonder if they thought they would be getting more air under the last step...
hard to say, but IMO it pulls the nose down - common sense.

[tiqueman]

Jeff, heres a little more clarification of the, what I see, as a small issue. I just took pics of a hull I havent built yet. First pic is the forward most step surface. 2nd is the last step. In theory, no matter where water hits that last step, because of its down angle and its different more negative angle than the stp before, its going to act as a tab, because, no matter where water hits it being its the last thing water touches when leaving the ride surface of that hull, its being deflected down, which pushes the nose...........

[tiqueman]

Crap now Brian knows my secrets... LOL. See you Sunday.

[RCKong]

yep... I have a set of prop shop SS 4714/3's I might test out too this weekend.

[monojeff]

Yes I do now understand what your saying.
It is clearer now with the extra details.
I was a bit confused on things that were being described and how they related to the way the boat rides.
In a nut shell at the moment the boat basically never gets on step especially with the twin motors and lack of adjustment.

I see now in the picture the last step does have a negative angle and would cause the issues you have described.

[tiqueman]

It gets on step, its just when it tries to lift, its forced back down... so if thats what you mean by it doesnt get on it, then no? lol

I still feel it is a fantastic boat, even as is right out of the box. Super stable. And Im not trying to imply this modification HAS to be done or your boar will suck... NOT AT ALL, its just going to help tru it a bit. Its the exact same concept as i mentioned in my first comment about truing a hull, or blueprinting. As is, it has like a "step hook". And just like described as in a mono, if a mono has hook, even if the transom botom is the same level as the area of the hull before the hook, being the last part of the hull that touches the water is angled down, its going to cause the nose to dig. Same principle applies in a cat.

Batteries.... Just had to say it because its what the thread is really about. man we are off subject.

[properchopper]

Man I'm really breakin' my promise to stay back, BUT I just had a thought (happens at random intervals). Seems my customer's Cheetah and mine are both single motor boats.
Neither of us have experienced a "too wet" running attitude (so far at least). And given that one condition that contributes to running too wet, or if you will, nose down, is the effect of prop lift. When lift picks up the rear, the nose goes down, and there's the crux that might be operating in dual motor rigs. Twice the prop lift with two props. Might be worth looking into. OK, now time for a cheeseburger

[tiqueman]

A wise observation... however lol... same props work fine on all my other twins. Its the hull. I can make the worst hull run better with strut/ stinger angle. But I don't like Band-Aids. Those effects typically scrub speed and cause erratic behaviors on and off throttle. Not my cup of tea. I can't believe a truing hull argument has gone on this long. Its been proven thousands of times already.

[tiqueman]

Wait.. I wanna burger too!

[monojeff]

It's a very informative thread regardless talk about a lot of parts of setup and how they effect things.

I see it as this if the boat has built in tabs for some setups maybe that's a good thing.
Don't get me wrong making that boat capable of going faster better is good for some but not everyone will handle it so well.
It's like a wheelie bar....

[properchopper]

A wise observation... however lol... same props work fine on all my other twins. Its the hull. I can make the worst hull run better with strut/ stinger angle. But I don't like Band-Aids. Those effects typically scrub speed and cause erratic behaviors on and off throttle. Not my cup of tea. I can't believe a truing hull argument has gone on this long. Its been proven thousands of times already.

Now that you mention it, with the positive strut angle on mine I was experiencing some Oh-So charming (butt clenching) wheelies when I punched it at 1/2 to /3/4 throttle

Enjoy : http://www.youtube.com/watch?v=OJi4bln-hHQ

[tiqueman]

Awesome.

You're right on Jeff. And in glass water, its a wicked machine. In chop, not so much. Those wheelie bars effect too much when its bouncing around and your boat disappears into the abyss for 5 seconds or so... which is equally butt clenching lol.

[monojeff]

Trust me I know how that is with my scale boat I have been under equally long at times trying to run in some serious chop!
I hope you have good pics of the process you took to do the pads on this!
Also do you have a build thread going for any of them?

[tiqueman]

Unfortunately no and no. I've been doing so many builds its too time consuming to post every detail on all. My twin cheetah took 5 or 6 months because I was so involved in other things. My ride pad truing is pretty straight forward. Filler, block sand, repeat until u like it.

[tiqueman]

Well gents. the results are in. We had a test n tune day today at our club meet. I must say, one would be foolish not to correct the angled last step in this hull. No adjustments were made other than the filling and it was a totally different beast. Im going to have to level out my stingers because in chop I think its going to be running too light. We had an unusually calm day at the park today which was great because it showed how nicely the hull was actually running. I had a few electrical problems to sort in a one of the escs, but finally after half the day I was able to pull more than one lap. Video to be up as soon as our videographer from the club loads them. Ill post it here but can also be found in our "run day reports" thread in the club section under west Florida Model Boat club.

[monojeff]

Sweet! Good news!

[tiqueman]

Awesome news Jeff. I cannot tell you how pleased I was w/ the outcome. I knew from past boats Ive had to "help" it would make a difference, Im just amazed how much better it got.