mestarinico

Thanks for the information. That thing is FAST!

colosus

Wow....well done Norbert,.....very very fast...its taken you a little while but look at that hull fly man...nice..now im jealous hehe

I may have missed a page here..did you test the weight of the hull with all hardware in and also without....how much was it.. ?

Looking at that last video...your gunner need to move the batteries further forward...or add weights...also a little tip you can get airbags that come on a roll about 2-3inch long bags for postage items these are perfect to fit near the front of the hull...incase of an over turn..it should pop up the right way up..but you may know all this already..

Nice job m8
I sent you a letter to your address some months ago, but i never got that plan you said..maybe you were too busy..

norbique

Dear Mathew,
Please excuse me for my error. I totally forgot about your plans! I thought I already sent them to you. I sent the plans out to quite a number of people.... sorry.
I still have your email so I'll send the plan to you ASAP!

Norbert

ThomasSalin

Hi,
Could somebody be so kind and email me the drawing of this hull?
I can PM my emailaddress

///Thomas

ThomasSalin

Hi,
Could somebody be so kind and email me the drawing of this hull?
I can PM my emailaddress

///Thomas

colosus

Hi m8

Its Norbique who sends out the plans, you have to PM him nicely, but i think he is extremly busy cos he also forgot me for some time now...i do have the plans but he was going to add something for me in the plans and has forgotten... but anyway Norbert needs to give the ok...

ThomasSalin

ok, I wll contact him..
Thanks.

norbique

Hello everyone!

First off please sexcuse me for not reacting on your requests in time.
Those who have the plan can share the plans with others I got it for free as well. As far as I know they're not copyrighted or anything.

Colossus, which part did I tell you about that I've forgot to send you?

Since the video posted above I've adjusted the outdrives, replaced the shafts, I had too much vibration on them. The new ones are better, but since they're about 10mm shorter than the old ones were, the props are 10 closer to the transom, and this makes the boat more prone to blow-overs. I had her run several times and I can tell you she flies just beautiful!
I'm still trying to counter balance the effect but not much success so far. I tried moving the COG forward, helped a bit, but didn't solve the problem completely. I also think the RTR weight of the boat is also less than what it should be, which is 6.5kg, little light for the size of the boat.

In the meantime I began working on another boat, roughly the same size as the lithium cat, but different design. It's gonna be beautiful! But more on that later.

Tomas, I'd like to see photos/videos of your max cat.

And finally here's one of the latest videos that I uploaded:
[youtube]http://www.youtube.com/watch?v=218m-yuM4g8[/youtube]

Norbert

ThomasSalin

I received the plans,
this will be an interesting project.
Thanks!!

colosus

Wow......She runs just beautifully ..she looks almost like the Mystic C5000..

Its an amazing creation...all that time...and hard work...job well done...
When is the Fiber vision coming ...lol ??

Hi Norbert ...it was the transom that you made..which is not in the plans, you created your own transom for the rudder to make it look and handle more like the Mystic or King Of Shaves....and boy it works just great...i asked you a while back if you can make the plans to 135 and add that transom design to scale too..and you said no prob..send my home address and you'll do them.....i know your busy..so no mega rush...
Im just happy you finally got it running really well...although i think it needs a tad more weight in the nose...

Lol my time was divoted to a 3d model...but i sort of gave up..completely created by me..

norbique

Nice work colosus!

I remember now. The rudder holder is a part which I made on-the-fly while building the boat. So only photos exist. I will have to design those then scale up to the size you need.
Let me work on that and I'll get back to you.

BTW the new boat i'm building also hasn't got that part designed....

lithium cat splash
[youtube]http://www.youtube.com/watch?v=PlhRm6RqTAA[/youtube]

colosus

Hahhaha

Looks like you need to make a template....
Atleast i think its universal...you should be able to use the same template for most boats...

If you watch how you boat fly's and handles.....do you think the transom rudder holder is long enough ? just watching that last video looks to me like it needs more weight in the nose.....and maybe..just maybe that transom should be a little bit longer, i think the longer it is the more stable it is, maybe have a look and make an extension plate to make it some centimetres longer..and try it..i dont know what you did in the last video but she is faster...

can you post a pic of the back so you can see the length of the transome and rudder ?

colosus

forget that about the transome...i think its long enough...
I just checked the MHZ and HPR hulls and i think you may have it spot on..

maybe those outdrives are too short...or its the angle..

Oh i found another speed controller to check out..people in Greece have been using them with the MHZ Mystic C5000 hulls..
here's the site.. http://mgm-compro.com/index.php?tid=...-32-bit-system
Incase you havent seen em before that is..

And ofcause the all new Miss Geico.....new Fin ? http://www.youtube.com/watch?v=634gz...feature=fvwrel

colosus

Sorry for yet another post but maybe for good reason....

Here is the setup of an HPR 135 hull..

ngines: 2x Scorpion 5035/760kv MHZ
controllers: 2x Hifei Swordfish 240A HV
lipos: 2x 12S1P Turnigy Nanotech 5000 45C
props: 2x Octura X457

and the video here :

http://www.youtube.com/watch?feature...&v=Gxc75YivDF4

Watch it and listen to it... it seems to stay in the water all the time, it seems to have no bounce...where as Lithium Cat is very fast but bouncing...need to move more weight forward ...im sure..

and a little pic of the transome on HPR

norbique

Tha MGM controllers are very good stuff. Not cheap either.
My outdrives ARE too short I know. but I had shortened them to lower vibrations. The whole outdrive unit is cheapo chinese stuff, now I know intended for slightly smaller boats. but at the time of the build they seemed OK.
The new boat will not suffer from such problems. outdrives ~15mm longer than the litihum cat. larger diameter shaft and flex shaft as well.
As I wrote earlier the initial drive line was more stable becuse the props were 10mm farther back. I'm just trying to do best with what I have.

ThomasSalin

How long should the outdrives be?

///Thomas

colosus

I think they should be 150mm long....just like for a cat just over 1metre long...
The Lithium Cat is 1.1metre and if you look at MHZ Cats there 114 Mystic Cat has 150mm long drives..

http://mhzusa.com/Scale-Drive-for-My...m-m-1674-A.htm

But Norbert used cheap Japanese drives and will maybe change them some other time...

I want to make the Cat as 135 but i dont think the 150mm drives will do for me...

colosus

Guys...what should you look for when searching a motor for a powerboat... i.e Class 1 Cats or P1 Monos...

If you see a video i posted using the Scorpion 5035/760kv the boat is very fast...yet if you check other versions like Scoprion 3226/1600kv for Helicopter the Kv is higher...is that better...?? you can put a water jacket or cooling system and then its for a boat..

So are you suppose to check what Kv it has and how many Amp's it needs..the lower the Kv the better.. ?? i thought it was the higher is better...?

Like my Lehner 2250 9winds has 160amps...so it needs 160amps to power that motor..which takes 24cells or lipos.
can some give an example of cheap motors that are just as powerfull..and what you need to look for when buying a motor please..i have no concept on motors..

norbique

It's not the length of the outdrives but the distance from the transom to the prop what matters.
I read/learnt from others that this distance should ideally be between 12-15% of the length from nose to transom. But a minimum of 10%.
Unfortunately in my case the length of the hull from nose to transom is around 1000mm which means I should have about 120-150mm distance from transom to prop and I only have 95mm on the lithium cat. This is where bad blow-overs originate from.

The MHZ outrdrive is 150mm long, however the distance from transom to drive dog is only 122mm which shows the above formula is correct. About 135mm from transom to prop including the drivedog which is right in the middle of that 120-150mm given by the formula.

I'll write more on motors later, gotta go now sorry.

norbique

Colossus.

Motor KV is a value which tells you how much RPM you'll get for each Volt you power the motor with. This value is given by the motor manufacturer and although it is never an exact value (since it can fluctuate depending on load and some other factors as well) we can generally take it as something constant.

To calculate the RPM of our motor we need the folloing formula:

Motor KV * Battery Voltage = RPM

For example a 2000KV motor at 3S lipo looks like:

2000KV * 3x3.7V = 22200 RPM.

But since this is only theory. In practice voltage drop under load and friction all take off of your actual RPM on the prop.

The KV rating helps you find the right number of lipo cells to reach a desired RPM.

The higher you go with the battery voltage the lower KV rated motor you'll need to get a given target RPM and vice-versa.


Some other info: The bigger the KV rating of a motor, the less efficiency it has.

To obtain the same RPM, the 760KV scorpion motor powered boat probably uses 10 cells in series where the 1600KV motor would only need 5. Both would give you roughly the same prop RPM, but there are a number of differences between the two setups. The 10S setup uses more battery, HV ESC and is probably more expensive than the lower 5S setup with the LV ESC etc. But the 10S setup with the lower KV motor would yield better efficiency than the higher KV motor. Resulting in cooler running gear, and probably longer run times.

The number of cells you can use is determined by the ESC you use. Generally talking we can say that many LV (low voltage) ESCs have a limit of 6S batteries. Those which go over this are usually called HV (high voltage) ESC and they can support up to 10S packs or even more.

If you have a HV ESC you can go with higher voltage and a motor with lower KV rating.

In the Lithium Cat I went with the 6S setup because I use ESCs which can only take 6S pack max. they're LV ESCs so to speak. With the 6S packs I use 1400KV helicopter outrunners. This setup gives me a theoretical 1400KV * 22.2V = 31080. Actual prop RPM is below 30K RPM for sure but I don't know exactly.

I could have gone with HV ESCs and use 10S packs and lower KV motors (800-900KV) but that's a setup simply too much $$.

Hope I wasn't too complicated.

ThomasSalin

Are there any heat issues with these outrunners? as there seems to be very little cooling (no water jacket)

///Thomas

norbique

Thomas,
The outrunners are water-cooled from the front. The motor mount has water cooling and it does it's job pretty well. Plus the motor endbell has holes which act as fans sucking air through the motor at a high rate. I never had the motors heat up to 50C.

Norbert

ThomasSalin

Thats good, I might use the same motors then

///Thomas

norbique

Which motors to use depends on how many cells you will use to power them as well.
The 1400KV motors I used push the boat to around 100km/h.
In my next build I'm going to use 1760KV motors and aim for 120km/h.

ThomasSalin

I had those 1400kV in mind. 100kmh is enough for me to start with

///Thomas