Simons Bigger Cat.

[Simon.O.]

Hi Simon, is it a new 9xl ? have you checked it has a wee bit of endfloat?

This is one of Chinas finest red cans! much like our best Red here
The bearings feel fine and there is a very little but not worrying ammont of endfloat.

I deffo need to get a jacket on this. Even the 7XL that was producing similar watts did not get as hot as the 9XL did with coil. Yes I know that coils suck and jackets are the go.

Now that I have a reliable power system I can play with the strut again and get that nose off the water more.

At the moment it is very light on all the pads with a Grim 40mm 3-blader.
The CF40 is getting the nose up and the hull wil ride on the rears as I like my cats to do. The CF40(left) is now rooted thanks to some surface debris.
I have a 40r that I can flick on in the morning.
All props bigger are out at least until I get the jacket and strut sorted.

[Brushless55]

what prop do you like with the 9XL?
I'm not much for the know how of props and need one for my MM 9XL
thanks!

[Simon.O.]

So far the Grim 40mm 3-blader is good.
http://www.offshoreelectrics.com/pro...od=dh-aqub9720
I also ran a 40mm CF
http://www.offshoreelectrics.com/pro...od=grp-2317.40
That was fine until it hit something hard.

The next test will be a 637.

[Blueprint]

Hi Simon, we have a SAW meeting on the 17th January at Hakanoa, why don't you enter and try your boats out and meet some of the other Kiwis going for Speed. Check this website out and go to News for speedrun info http://www.speedclubnz.co.nz/

Merv

[Simon.O.]

I know it has been a while since I have been on the pond, busy here with summer jobs.
I ran this one yesterday morning on 5S via the Mystery to the 9XL
The Grim 3 blader was fine but that got lost from another hull later in the morning.
The 637 was a lot of fun.
A 640 and over was just a heat generator.

The 637 was able to spin up and the numbers suggest arround 30k at the prop.
I got it aired out, and it can air out a bit more too, and riding the tail for a honest high 40's by eye.
My Garmin is blowing bubbles so I get to eyeball for now and this hull looks fine on the water. That is all it was built for and I am happy.

I will raise the strut a bit more and see what happens.
I know my little cat gets hot but goes nuts with the strut a bit low.

If I can get it right up on the rears and the prop screaming I do not really care about an accurate speed. I want this one to look right and sound right, it does also have to go rather quick......

I may end up painting this one.

[Brushless55]

between the 40mm Grim and the 637, what prop did you like better, and why?
thanks

[Simon.O.]

The 40mm Grim 3 blader is a bit less than a 440-3 from what I have read. It bites well and spins up well. As you know I am a mad fan of rpm for speed.

The 637 was quite similar in performance. The added pitch gives it bite but the lower dia allows a good spin up. I think both are close at the end of a 100m drag run.
Different hook up characteristics and slightly different top speeds, the 637 being a bit quicker I would choose the 637 again.
This is now a bit academic as my Grimm 3 blader is holding down some silt on the bottom of the pond.

The 637 rocks for me.
There are the rigger props to try yet

[Brushless55]

right on, thank you!

[Simon.O.]

O.k we have all seen the video now and can see how it sucks onto the water.
This was deffo a bad day for me.
Earlier in the morning I had this thing on its tail well with a K42.
This cat likes a 637 a bit but really likes the 42mm dia props, just not X6 series !!

I have had the strut all over the place to find a sweet spot but have not found it yet for any period of time. The 637 is ok and the 642 has too much lift in the rear I think.
The K40 and K42 were good until they blew apart about 50m down the straight. I have now decided that a 1.4 or X4 is they way to go and have one of these on the way as I have a few bits coming from there.

http://www.astecmodels.co.uk/catalog/product_info.php?cPath=25_99&products_id=815

It is a 44mm and that can be easily set to 42 if needed.

I now need to try a few different strut heights/angles and CG settings.
My smaller cat that died was so much easier than this.

BIG Question
How anal are we about the 30% CG factor ??
I am keen to run this one with about 2deg on the strut and run the CG backwards to see what happens

[crabstick]

BIG Question
How anal are we about the 30% CG factor ??
I am keen to run this one with about 2deg on the strut and run the CG backwards to see what happens

Move the CG Back until it blows over then move it forward a notch

[Simon.O.]

I ran this cat today with a few new props, Scott(ozzie-crawl) sent me a 537/3 and a 440/3 that are properly S+B and tweaked a bit. I have a newish 442 that needs balancing.
The 537 was not for me and the 442 was a bit loud.
The 440/3 was nuts !!

After asking Matt about the thrust angle I was game to try a bit of up at the prop.
It is all measured and comes in and near 1.5deg positive.
The first few passes were fine and then it all got exciting. The pond I run in is quite narrow for one half and a wake stays for a while. I was on my way back south and into the wind when I parallel crossed a wake and this upset it all.
First blowover !!
The headwind was a contributing factor along with the very unsettling parallel wake, sheer speed was the final factor.
This now runs a lot quicker than it did in the vid I posted a while back and the components are a lot cooler too.

I managed to get this one upside down 3 times today and each time was into the wind. Out of about 10-12 passes I see that as running on the edge and will keep it that way. I may add a bit of lead up front to move the CG as everything else is already well forward.

I was so happy to see it tail ride and then blow off. It now means I have it set 99% right.

Thanks to Scott for the prop work and to Matt for the tech advice.

[crabstick]

440/3 is a fav prop of mine.. good rough water prop for my whip on the 8xl

Before the lead, try either more positive strut angle or moving cog with battery.

After that id try a small air dam inside the front of the tunnel to reduce compression

[Simon.O.]

Before the lead, try either more positive strut angle or moving cog with battery.

After that id try a small air dam inside the front of the tunnel to reduce compression

More positive strut angle?? wont this cause the bow to go higher and thus more prone to blow offs. I was always under the impression that positive angle meant prop up and therefore bow up.

The main packs are as far foward as they can go, insted of lead I can split the 5AA Rx pack down and shove it up in front of the motor.

I can play with air dams as I did a long time ago with the smaler (now dead) cat.

[crabstick]

sorry i meant negative, should have checked what i typed. Try a bit of angled balsa in a v shape near the front of the tunnel..

[Simon.O.]

sorry i meant negative, should have checked what i typed. Try a bit of angled balsa in a v shape near the front of the tunnel..

Though so on the strut angle bit.
An air dam is easy with wads of trailing edge balsa loafing about here.
If I do the tunnel entrance dam, what are your tips on that game.
Flat side forward or pointy side forward, down near where it goes flat through the tunnel or up a bit towards the bow.
If it is all a bit hit and miss then I am keen to play that game too.

I am so happy to see it go fast enough to blow over It is not as fast as the big rigger but it is quick and looks good. That was the main performance requirements for this hull.
The small cat hulls will have different requirements. TBA