K90 KINGCRAFT in JAPAN

[Hammerhead]

Hey Dale!

You're gonna (#%$#) your pants.

I changed the bearings. Got 112 out of it. I tried to crank a

corner at full blast. Didn't flip, but after the corner, the stability

went to (&%$#). Got it back to the shore with out flipping it.

The turn fin was bent 45degrees out. That is 3mm of hard aluminum.

It experienced a lot of G force.

Yikes. Can't do that again.

 

[Twin_k90]

Hammer,

Bloody hell!!!! told you they will turn flat out !! that fin is 6061 T6 aliminium, time to throw some 3mm stainless on there, i have never bent a fin like that ever, man i cant wait to get my new one going, i have the hull, will order the hardware next week, have a motor organised just have to get the funds together, damm money, i need more!!

Are you still running the 460/3?? or are you running the 6514/3??

Dale

 

[Tony Jacuzzi]

Curious what this statement meant:

snip "I changed the bearings. Got 112 out of it. I" snip

112 what ??????

Thanks Tony J

 

[Twin_k90]

112km/h or 69.6mph, not to bad for a mono in circuit trim!!

 

[Hammerhead]

Hey Tony! K90 and I are from the world of kilometers. Our club used to have a Mph radar, but it bit the dust. The new one we got is made in Germany, so it is kilometers.

K90! I'm going to the hardware store today to pic up some stainless. I think 2.5 is the thickest sheeting I can get without special ordering.

I will give it a shot. I will try some 3mm carbon, too. It is a little flexible, but at least it will go back to the original shape. I don't think that I can get the T6 quite back to the original postition.

Hammer

 

[Twin_k90]

Hammer.,

2.5mm stainless may have the same problem, 3mm carbon should be ok, you have to bring the boat over here at chrissy time and woop everyones butt , you and Ian Inverarity will be the Kingcraft mono guys!! Dont think mine will be ready to go by then

ill talk to james this arvo and let him know about the turn fin and we will try and get something a bit stronger for the next shipment of boats.

 

[Twin_k90]

Hammer,

Hows the boat going?? have you run it again with the new turn fin on it??

Dale

 

[Hammerhead]

Haven't changed it yet. I will take a pic of it before I do change it tomorrow. That way you see how much it bent. You wont believe it.

Hammer

 

[Hammerhead]

This is the pic of the turn fin folded out. It was folded out more, but I thought if I bent it back, I could get a few more runs in that day. So, I tweeked on it a bit. Nothin' happenin! I tried to put a 3mm carbon fin on her, but it was too floppy. I went ahead and repaired the old one so I can go run it tomorrow. I will have to take it easy in the corners until I get a 3mm stainless one made. Had to special order the sheet of stainless. Nobody has it in stock unless you buy a 1X2meter sheet.

Hammer

 

[Ian Inverarity]

Hammer,

Bolt the turn fin to the inside of the bracket instead of the outside, this will make it much less likely to bend! ;D

I have just put a K-90 in my Kingcraft, but I am not going as fast as you yet! My boat is this one: http://members.optusnet.com.au/~kingcraft/.../Ian%20mono.htm

If you dont mind me asking what prop and pipe length are you using? And nitro?

Thanks!

Ian.

 

[Hammerhead]

Ian!!! ;D

Welcome aboard!

I've heard tons about ya! Looking forward to hearing your inputs.

Thanks for the suggestion. I will try to put it on the inside tomorrow.

I'm running an X460/3 I had it tweeked to 4.0 and I decreased the diameter 2mm. This is top secret information. Don't tell anyone :

I'm running a titanium pipe (KICKS @$$) at 282mm

Using an O.S. 9B carb with the idle needle set at 3 turns. It's a little richer than the original setting, and I have the high speed needle set at about 1.5 turns.

I replaced the caged bearings in the con-rod with CMBs. Work fine. I would do it right now, if you haven't already.

I sent one of those titanium pipes to Dale. Check it out when it gets there.

See ya around dude!

Hammer

 

[Hammerhead]

Oh! One more thing! I had fuel made to Dales specs.

22% Klotz, 5% castor oil, 45% nitro methane, and

28% alcohol. Dale was right! These K90s luv da oily stuff.

Hammer

 

[Hammerhead]

Hey Ian! Nothin' happenin' with the turn fins. The inner corner is rounded on the mount, so they won't seat right, if I put them on the inside. Just gonna have to take it easy in the corners until I get some stainless ones made for it.

Hammer

 

[Ian Inverarity]

Hammer,

Can you notch or cut away the mouting area of the turn fin a bit so that it can mount on the inside of the bracket? This will make it much less likely to bend and you will get less deflection when it flexes.

The speed you have is really good! I am using less nitro (25%) but I also have my own cylinder head to get the compression up for the low nitro fuel. My engine is very new and I have not had much running yet, my pipe is still around 305mm which is where I used to run it with the A100. I am still running the Bolly carbon fibre pipe that I used with the A100.

I am using the stock carb, an OS 9B needle and have replaced the caged rod bearing with CMB needles, on Dale's advice!

But my props are much larger, I was running a 6514/3 and 6516/3. Your engine must be really screaming if you are running a cut down X460/3! My A100 used to run an X470/3 or 7016/3 at around 19000rpm, but such big props are too much trouble!!

When you say pitched to 4", I presume that is a measurement over the whole blade? Using one of Dales pitch guages I measure the trailing edge pitch of an X467 at about 6.5", that is stock! So I would guess that an X460/3 has more than 4" at the trailing edge even in stock form.

By the way I have been reading this forum for quite a while and I think those carbon riggers you made are pretty neat!

Ian.

 

[Hammerhead]

I think the stock pitch on an X460/3 is about 3.16. I had it made for me, so I don't know exactly what was done to it, but If you take an X457/3 and take the pitch to 4 inches, then I believe you will get the same effect. I tried the 6514/3. It was okay, but it took forever for it to wind out.

Our course has shorter striaghts than you have down under, so I need to get the punch right out of the corners.

I'm thinking about getting an x457 pitched to 4.2" to see what happens. It might bend. Hmmm. Never know till you try, though. I've bent a lot of octuras with my hydros. They are pretty thin.

Hammer

 

[Ian Inverarity]

Hammer,

With your pipe so short I am not surprised you have difficulty running the 6514/3, mine jumps up on pipe straight away on that prop and maintains good speed thru corners. I generally set my boats up to be fast thru the corners, and my mono is the fastest thru corners that I have seen!

Unfortunately my prop shaft is 1/4", so I cant fit a X457/3 or X460/3 as these are both 3/16" props. However I am thinking of cutting my X470/3 down to about 62mm, once cut down like that it will have a lot more pitch than a X460/3 without having to add any.

I have never seen an X4 series octura prop bend on a mono so I think you will be pretty safe there!

Do you know where your CG ended up?

Ian.

 

[Hammerhead]

I have a 5mm shaft. I can put the big props on with a collar sleeve. I like this set up, because I can use any prop. With the kingcraft stock strut anyway. I wouldn't be able to do it with the Japanese stuff.

I think the reason I was dogging in the straights with the 6514/3 was because my flaps were set for the X460. The 6514/3 lifts more so, I was probable dragging the hull. The 6514/3 seemed faster in the corners, but when I straightened the boat out it would dog down. I will finish this season with the X460/3. Last race on 11/24. After that, I will have 5 months to play around with different set ups. Speed is what it has now, but in mono classes, speed isn't everything. I want to get it set up to run about 95Kph, and handle at full throttle through the whole heat. That is what I consider the perfect racer. I'm going 110+ now, but I don't think I could survive a heat at that speed.

For now, I will just have to take it easy with the throttle, and use the straights to blow by everyone. When I race hydros, I would always do my passing on the back stretch or coming around bouy No.4 Don't think I will be able to use the same technics with this boat until I get it set up better.

Looking forward to any advice you have.

Hammer

 

[Ian Inverarity]

Hammer,

The Kingcrafts are very fast in corners, you should be able to hold full throttle! For me the corners are the best place to pass as it seems everyone else I race backs off and runs wider.

95k is a good speed for heat racing, when I was running the A100 the boat was a lot more consistent running about 95k rather than about 104k.

Another prop I have seen work okay on 90 monos is an ABC S-30/4, this has a lot of pitch, 4 blades and is only about 60mm diameter.

Ian.

 

[Hammerhead]

Hey Ian!

I was able to crank through the corners at full blast until I bent my turn fin. I will have to get them set up so they don't bend before the race. I think if I change them to 3mm stainless, I won't have any problem. I have a small sheet on order. I will make them the same shape as the ones that came with the boat.

I checked the CG. It is at exactly 29cm from the transom.

This is with an empty tank.

The tank is mounted on the left side(looking at the transom) between the rail and the body. It is kinda tucked under the deck. The tank is 18oz and the center of the tank is 25cm from the transom.

Hammer

 

[Twin_k90]

Hammer and Ian,

Spoke to the hardware maker last night and we are going to use different brackets for the turn fins and use 2 bolts to hold the fin on, we think the problem is being caused by lack of surface area, hopefully this will fix the problem,

I ordered my hardware for my new boat last night, wont have it ready for nationals to