JAPANESE HYDROS

[Chris Wood]

First off lets get this out of the way.. i am not bashing japanese style boats at all so anyone that starts on this.. please go outside and play ok. or come talk to me in iowa.. it gets old.

I have been studing video's and pictures for MONTHS.. both jae boats as well as others and spent HOURS on other websites over sea's.. and there are a couple of things that have gotten my attention and i don't know why.. or whom to contact oversea's if any at all to ask.

( again this is hydros not mono's )

1. every boat. every video every picture all the hydros run SMALL VOLUME PIPES? why is that.. look like mac's pipes or something.. not sure.. very skinny bands. LONG divergant ( not sure on the spelling ) cones.. ect.

2. they either run motor forward type boats.. or the boat is 8'long with the motor back.. i would guess the super long boats are for running in the ocean..

i can understand the motor back situation.. but with such a foot print.. and super long boat.. why motor forward?

SO, ROD, RON David.. whom ever.. your thoughts please.. i just thought this was interesting.. i am big into details.. studying things over and over and for some reason i have in the back of my head this is SUPER important and i don't know why. lol

chris

 

[Geraghty]

First off lets get this out of the way.. i am not bashing japanese style boats at all so anyone that starts on this.. please go outside and play ok. or come talk to me in iowa.. it gets old.

I have been studing video's and pictures for MONTHS.. both jae boats as well as others and spent HOURS on other websites over sea's.. and there are a couple of things that have gotten my attention and i don't know why.. or whom to contact oversea's if any at all to ask.

( again this is hydros not mono's )

1. every boat. every video every picture all the hydros run SMALL VOLUME PIPES? why is that.. look like mac's pipes or something.. not sure.. very skinny bands. LONG divergant ( not sure on the spelling ) cones.. ect.

2. they either run motor forward type boats.. or the boat is 8'long with the motor back.. i would guess the super long boats are for running in the ocean..

i can understand the motor back situation.. but with such a foot print.. and super long boat.. why motor forward?

SO, ROD, RON David.. whom ever.. your thoughts please.. i just thought this was interesting.. i am big into details.. studying things over and over and for some reason i have in the back of my head this is SUPER important and i don't know why. lol

chris

#1.They evidently have easy access to MACS pipes and they must like them because you do see a lot of MACS pipes on the Japanese boats......other than that I don't have a clue as to so many MACS pipes....

#2.I would be glad to answer what ever you want but.......I am confused as to what your question is???????.....what do you mean by a motor forward boat????

 

[Chris Wood]

rod,

i seen on the BIG boats.. i call them ocean boats.. really really really long.. the motors are way way back toward the transom.

on the smaller what i would call more normal boats the motors sit much much further forward.

my thinking is it would just the opposite since the big boats are so long.

does that make sence?

 

[JRXHydros]

http://ne-stuff.blogspot.com/2008/12/japanese-style-rc-hydro-boats.html

 

[Chris Wood]

http://ne-stuff.blogspot.com/2008/12/japanese-style-rc-hydro-boats.html

i have been there many times.. looked at the pics.. but it still don't explain much

chris

 

[Ron Zaker Jr]

http://ne-stuff.blogspot.com/2008/12/japanese-style-rc-hydro-boats.html

i have been there many times.. looked at the pics.. but it still don't explain much

chris

B Daddy,I don't understand your question on engine location.I THINK the small volume pipes can be used with the "freeness" of these type of hulls. They also run X props,figure that one out?????

 

[hydro rob]

have you seen the videos of those guys reacing in 2 foot swells hanging off the back of a bayliner running a rigger? NUTS!

 

[Jorgen Andersson]

Hello Chris

I think I understand your question.

As I understand it, they move the balance point on the boats you call "ocean boats". They are designed to run i real rough water and when they do, they are airborne lots of the running time. They are balanced to "fly" well and not dive on the nose into the next wave.

I have seen videos on this and I would say that sometimes they are in the air like 30-40% of the running time.

In these kind of races they just race in a straight line for miles, turns around and go back to starting point, best time wins.

Pipes - Earlier they did not run very much with higher nitro contents in general i Japan. This could still effect the pipe designs they prefer.

I have worked for Kyosho for many years, and during some years one of my contacts was running hydros, during thoose years he told me a lot around their racing back then.

Thanks

Jorgen

 

[Grimracer]

I would say weight to speed ratio is the reason for the CG change..

The 3 pound boats likely run (or are capable of) just MPHs under the 1 lungers..

Grim

 

[Chris Wood]

hey z.

maybe i am just explaining it wrong

lets look at the current boats of today.. my boat.. ninja's blackjack's ect.. have what most consider the motor forward approach.. meaning further forward to have weight transfer forward..

on the what i call OCEAN BOATS i see over there.. the boat is super long.. like jorgan said.. but the motor is way way far back.

on some of the more recent boats over seas ( shorter version like the jae ) the motor is much further forward.. more like the boats we typicaly run here. aka my boat, ninja's hawks jag's ect.

i guess what i didn't understand was the ocean boats.. being so long, with a super wide stance.. why have the motor so far back.. i am guess it is like jorgen said to keep it from nose diving. but the curious thing is the more typical japanese boats have the motor further forward, more like or convetional hydro's we run here.

with that being said.. my point for all of this is this.. the jae boat has a wide foot print, but narrow running surfaces.. with the motor much further back than our conventional boat.. so how do the japanese run there boats similar to the jae for length and stance, but have the motor so much further forward?

does any of this make sence or am i just typeing for nothing LOL!!

and yes the X props.. i have no idea. but i seen a video of a boat that absolutly SCREAMED. and i have no idea what prop it was.. I used a online conversion and according to a record set back in 99 it was around 130mph.. take in mind back in 99. so where are they at today?

i am sorry if i have lost everyone on this.. i probably should have just thought about this and not posted anything lol

 

[Speed Jr.]

Hey Chris, how have you been buddy? First off, what do you distance the motor from to be considered forward or back? What the JAE team has discovered/found from these Jap boats, that it has absolutely nothing to do with the trailing edges of the front sponsons. I remember building my hawks and slamming the engine as far forward as possible and finding the COG as close to the trailing edge of front sponsons as possible. The Jap boats (im not sure but is seems to me) found what the key was.....the LEVER. The Lever is the TURN FIN. The trailing edges of the sponsons meant nothing when it comes to turning and in most cases, balance. So why not push the sponson bottoms out further forward for a larger more stable stance? Thats what they got. You cant compare the engine being forward or back compared to the conventional outriggers because of this...its not apples to apples...Everything is different. I think the boom spacing throws some people off too. You may think the engine on the JAE seems more forward, but if you draw the triangle from prop to front sponson trailing edges, you will see that the motor is exactly in the middle of the triangle, where on conventional(blackbird/hawk/eagle/etc) is towards the top of the triangle. You really have to forget what you know about the conventional outrigger to understand the Japanese boats and the JAE for that matter. We here in the US dont need the super long front end since we dont race in 1 ft. chop.....although it could have come in handy last year at Naperville right Chris?

Jr.

 

[Chris Wood]

lol ya naperville would have come in handy..

my thoughts really had nothing to do with the trailing edge on the fronts.. as i realize the fronts on the japanese boats are further forward. more the location from the transom is what i am looking at.

maybe i will try to find some pictures of what i am explaining.. that might make more sence once you see what i am talking about.

as for the engine on the jae.. from everything i see it looks further back than a conventional rigger we know today.. as best i can tell anyway.

i will do some pic searching when i get a chance.

chris

 

[misshydro]

from the pics on these rigger. they looks to be back 3".. I love the pinkie one.. love to build that. .. looks to be two different rigger on the motor location. couldnt find the one that sits closer to the rear transom.

 

[Speed Jr.]

Gotcha Chris. From the Transom makes sense. I too have seen some Japanese boats that have the engines really far back. Most of these are really strait line ruff water boats. The some that are built for oval still have the engine a little further forward. What do you think about putting an engine about 6" off the transom with the Turn Fin at about 12" from the transom? You would only need about a 5 foot wide creek to run oval!

Jr.

Great Pics MissHydro!

 

[Jorgen Andersson]

Hello Chris

Ocean racing:

On the "ocean hydros" the engines sits far back as you do mention, but the distance from the transom is fairly "normal".

I think that practical reasons like flex shaft lenght, drag, lubrication and so on have been factors when they designed these types of boats.

Oval racing:

The different engine positions on JAE and Japanese hydros you talk about could have to do with how much weight on the prop the designer wants to have, in order to get the correct penetration at the rear and to eliminate hopping and unhooking problems.

Many things will of course affect this, like width/AoA of ski, height to the bottom of the boat from surface and of course prop lift.

Maybe this explains why many of the Japanese boats run with X props?

Thanks

Jorgen

 

[dwilfong]

Hello Chris

Ocean racing:

On the "ocean hydros" the engines sits far back as you do mention, but the distance from the transom is fairly "normal".

I think that practical reasons like flex shaft lenght, drag, lubrication and so on have been factors when they designed these types of boats.

Oval racing:

The different engine positions on JAE and Japanese hydros you talk about could have to do with how much weight on the prop the designer wants to have, in order to get the correct penetration at the rear and to eliminate hopping and unhooking problems.

Many things will of course affect this, like width/AoA of ski, height to the bottom of the boat from surface and of course prop lift.

Maybe this explains why many of the Japanese boats run with X props?

Thanks

Jorgen

Jorgen

That is very interesting observation on the set up . When running with a ski and the normal tail weight you do not need a high lift prop. this would unload the eng and make it possible to run a larger pitch. It would also eliminate the tail hop with the ski. Might have to rethink the prop choices on my new rigger build with the ski.

David

 

[Chris Wood]

hey jorgan

ya that makes sence.. i just wonder HOW MUCH TAIL WEIGHT IS TO MUCH? some of the boats i have seen the motors are way way back.. i would think it would drag around the whole time.. maybe not though.

larry,

lol you going to put the radio box up in the nose? i thought about that but what a mess with a fuel tanks and boom tubes lol

chris

 

[Jorgen Andersson]

Hello

I have been in contact with two boat racers in Japan the last days.

They have given me some detailed information about the Japanese racing scene.

I will put this together in a post tomorrow, some of the facts are interesting....

Thanks

Jorgen

 

[misshydro]

just remember guys the ones with the engines tords the rear are mostly used as off shore ocean racing that can handle chops... Proubley they have the engine that far back to keep them form submarining into the water when it lands from wave to wave chops,kind of counter balance. Would like to build the pink one thats sit 3" back from where our engine sits at.Wonder where I can find the plans to that at? :huh:

 

[Jorgen Andersson]

Hello

Here we have some facts around the Japanese racing and rigger design!

This post has nothing to do with their "ocean boats" mentioned here earlier.

After my post #15 in this thread I had a "feeling" that I saw two different types of Japanese "heatracing" riggers in all these pictures.

And after watching the video on the NE-Stuff link in this thread a few times, I suspected that this showed a typical Japanese time trail on a very short course. http://ne-stuff.blogspot.com/search?q=japan

Niklas has just updated his page based on this info.

I have now been in contact with two Japanese racers that run in their National series and they confirm this, and has also giving me more details around their racing.

In Japan they run like this:

#1 - Heatracing with 6 boats at the same time, on an oval very simlilar to our racing. They run 5 laps i Japan.

#2 - Time trail with one boat at the time, on a very short oval, just 100m (110 yards) per lap, running 4 laps on time. The video shows one attempt on a race. A good time is like 17sec. These boats has nothing to do with heatracing, just SOLO racing!

Please look at the pictures:

CIMG1165 - Shows a typical time trail rigger set up for 4 short laps solo racing.

 

CIMG0337 - Shows a typical Heatracing rigger set up for 5 laps racing with other boats.

This explains very much of the different designs. It will now be a lot easier to think and discuss around this.

This was an eye opener for me, and probarbly will be for few others.....*smile*

Thanks

Jorgen