1:8 Scale MHZ Miss Bud....First one in the US...

[Turbosun]

Here is the new first 1:8 scale MHZ Bud in the USA
..Epoxy glass..red gelcoat to save paint weight. Decal set available...
2560 gram...very stiff.
Stunning....

[Steven Vaccaro]

Any way to get pictures with the wings and weight with the wings?

[Ladamercy]

Hi Turbosun,

congratulations, is it your hull? Was it a problem to get it to the U.S.?
I spoke to Ernest recently and he said that he could offer a carbonfibre version weighing 2000g including wings and cowling- for about 60,- Euros extra....

@pagemaster:
I had that hull powered with a 355 plett and 36 cells
If you want pics i can send you some.

Regards matt

[Ladamercy]

Here`s one...

[Steven Vaccaro]

Matt 4 pounds would be awesome!!!
I need one of those*!*!*!*!
What kind of speed and runtime did you get with your setup?

[Dan Chase]

Cool, I like it with the salt water scoop!

Now the race is on to see who's first to get one of these big bad boys on the water first! :D

You are going to cut out the painted windshiels and add a driver, right?!? ;)

[Andrewg]

5.5lbs it should be stiff!

[Steve Vasdekis]

I hate to be a party pooper but looking at the pictures the boat looks like it's a stand off scale model. Please correct me if I am wrong.

[Randy Naylor]

That is what 1/8 scale boats look like.

[Turbosun]

@Ladyamercy,

Ernest is here with me. He handcarried the hull.
Announcements soon.
BTW this is not my hull :-))
Sorry Dennis, could not not share.... :-))

[Jay Boyd]

Loo,you know MHZ hulls are @ the top of my list!

[Ladamercy]

Hi,

it had a BM355/45/4 Evo and 36x RC1700P&M cells onboard. The speed was 56mph and runtime never more than 3min. I used a X455 as prop.

@steve: it was more a take off than stand off model :D
http://www.rumrunnerracing.com/feforums/attachment.php?s=&postid=54113

Best regards,
matt

[Steven Vaccaro]

Matt you have my blood moving even more now!!! Great picture!
Looks like the real thing out there.

As you have most likely read in this post
http://www.rumrunnerracing.com/feforums/showthread.php?s=&threadid=9295
we would like to run a class this size in the USA.

Sorry for all the questions Matt, but are you able to attain a 50 plus mile per hour speed for 2 1/2 to 3 minutes?
I would like any opinion you have on a hull this size & power since you have already completed one.

Sorry to change the topic Turbo!

[Ladamercy]

Hi pagemaster,

of course i followed the thread and i think its a very good idea. I would love to see something like this over here.

If i had to build a new 1/8 scale hydroplane i would focus on the weight. This is by far the most crucial factor (from my experiences) for an e-powered hydroplane! Especially all the detailing is quite heavy so you`ll have to save weight on every components (batteryholder, spring steel-shaft,..)
I chose the Plett because at that time there were no reliable BL-controllers available. It was just to expensive to buy another one after each run...
A Lehner 2250/12 or /13 in combiantion with 30 or 32 cells would fit perfectly and if money doesn`t matter i would go for GP3300 cells (although they are very heavy)
The problem is that a hydroplane needs lots of power to get on plane. The large surface causes huge friction with the water and costs a lot of energy. So if you can manage to run relatively wide turns without loosing speed, highspeed can be maintained. If you loose too much speed in the turns, the pack will be empty after pulling the throttle 4 times...

I tested different props and cellcombinations but there was always one problem: when accelerating, a large prop was good to get the hull out of the water quickly. Once the hull is on plane, a small highpitch prop was better to reach highspeeds. So this is a bit paradox and it is very difficult to find a good combination.
I started with 30 cells and a X460/3. After setting the cg properly, i increased the amount of cells (36) and changed to smaller props (X455). The Plett offered around 24000rpm under load and i would consider this as minimum!
I modified the riding pads on my hull to ease acceleration (pic). This helped a lot as the original pads were to small (had 16cell inlinepack in each sponson).

Hope this helped you a bit.
Reagrds matt

[eddieh]

Danke sehr Matt!!!!
Matt thank you for the info, as one of the few who have tried this it is really valuable!!now it has me rethinking the whole shovelnose idea, as maybe with the lift created by the shovel with the larger ridepads, it might be the way to go. as for the idea with the props, hmmm, I suppose that if you had a large prop ut drilled holes in the blades which would let it slip while submerged but catch when on plane has just the opposite effect of what you want?
anyway it is going to be cool.
cheers eddie

[Ladamercy]

Hi Eddieh,

you`re welcome! I can only speak from my personal experiences but if i can help i will try it.

I wouldn`t drill holes in a prop because it will decrease its efficiency dramatically.
A better way to bring it up to rpm and hypercavitation is to aerate it. A small tube facing to the front end of the prop can solve this, the other end is just somewhere above waterline. The prop will suck the air trough the tube. This will allow to spin the prop easier and won`t have any affect as soon as the prop is only half-submerged.

Btw. i have some video footage of my miss budweiser. Just write me a PM with your email and i will send it.

Best regards,
matt

[eddieh]

Matt what a cool Idea little thought of things are so cool...!! that is an outstanding Idea!!!
my email is on my signature
ejhansen@comcast.net would love some video, again
Danke sehr !!!!!!:beer: :beer: :hail:

[Steven Vaccaro]

Matt that's the first I've heard of that. Can that be used with any surface piecing prop to help?

If you can email me the video at stevenv@gis.net that would be good. I would like to host the video so others can see also. If its ok with you?

[Ladamercy]

Hi Pagemaster,

yes it works! The idea is originally from real Class 1 cats that have split exhausts. As soon as the boat is on speed they can switch a flap to let the exhaust out of the "normal" exhaust tubes.

Lots of nitroguys use this because their engines often don`t have much torque in the low rpm range...

Clips are on their way!

Best regards,
matt

[Steven Vaccaro]

Ladamercy(Matts) videos.

First video is 2002
http://www.offshoreelectrics.com/Videos/Matts_Bud_09_2002.WMV

Second video 2003
http://www.offshoreelectrics.com/Videos/Matts_Bud_2003.WMV

[brooks93]

man thats pretty

[Dan Chase]

WOW, WOW, WOW!!! My Adrenaline is pumping now!!! :D

If that doesn't get F/E racers excited, they need to check their pulse!

Matt, thanks for sharing the video's! Steven, thanks for posting them!

:bounce: :lalala: :bounce:

[Steven Vaccaro]

New one
http://www.offshoreelectrics.com/Videos/oberto05_2003.WMV

Thanks again Matt!

[Kmot]

Originally posted by Ladamercy

I wouldn`t drill holes in a prop because it will decrease its efficiency dramatically.
A better way to bring it up to rpm and hypercavitation is to aerate it. A small tube facing to the front end of the prop can solve this, the other end is just somewhere above waterline. The prop will suck the air trough the tube. This will allow to spin the prop easier and won`t have any affect as soon as the prop is only half-submerged.



Brilliant!! :)

[Jeff Shriver]

After seeing these videos, all I can say is WOW!!!

[Otis]

Nice! I want one! :)

I think I speak for a lot of guys here when I say: You have our attention!

Any chance of some pics with the hatch off, hardware, etc?

[Ladamercy]

Hi,

here they come (please excuse for not posting them in the gallery)...

Regards matt

[Ladamercy]

next one...

[Ladamercy]

transom.
The flexshaft is a 3/16" standard
BTW: the exhaust tube is made of a pepsi can (polished and cut with scissors). Advantage: it is absolutely corrosion-free and ultralight

[Ladamercy]

front end.
I made adjustable flaps (via servo) but deactivated them later. They didn`t affect the boat`s attitude...

[Turbosun]

a Pepsi can??? You could have, at least, used a Budweiser can.....


BTW, the weight of 2650 gram could be reduced by a lighter lay up. However if you need to buy a new hull after you crash an ultra light, I think at the costs of these large expensive hull, your competitive edge may soon be overtaken by monetary constraints......

I just recieved the red wings and turbine intake/cabine cover. Will post pics soon before it needs to be shipped :=)

[Kmot]

Originally posted by Turbosun

I just recieved the red wings and turbine intake/cabine cover. Will post pics soon before it needs to be shipped :=)

Who's the lucky recipient? :D

[Kmot]

Originally posted by Turbosun
a Pepsi can??? You could have, at least, used a Budweiser can.....




ROFLMAO!! :beer: :doh: :yeah:

[Turbosun]

ahhh for the careful reader easily traced back..... :-))

[Kmot]

Dennis! ;)

[Steven Vaccaro]

BTW, the weight of 2650 gram could be reduced by a lighter lay up. However if you need to buy a new hull after you crash an ultra light, I think at the costs of these large expensive hull, your competitive edge may soon be overtaken by monetary constraints......

If someone is building a 2k rc boat and has to worry about crashing it, maybe someone building should rethink the whole idea.

[Turbosun]

well...ehhhhh......
So Steve, would you be willing to push the limit to the point of being so light that if crashed it is a loss???? There is, like any object of engineering, a balance.....

[Ladamercy]

Hi,

sorry Turbo- we don`t have budcans over here and a glassbottle just doesn`t look very good on a Hydroplane....

I would say that a fully equipped 32 cell- 1/8 scale Hydroplane should not be heavier than 6kg to get good performance and runtime.
As all the boats are supposed to be scale i would sand of the gelcoat to save weight. The hull will be painted anyway and the gelcoat adds no stability at all...

would you be willing to push the limit to the point of being so light that if crashed it is a loss????

I think despite all engineering you just can`t expect a hull to stand strenghts that it wasn`t designed for.
So you have two opportunities: make a lightweight hull with buoyancy or build something strong and participate at robot wars...

Best regards,
matt

[K.R.Joye]

Yes nice hull, wow a brushed combo that runs in the 50's! Now just imagine a hull almost 2 lbs lighter with the same fire power on 24 cells! Its coming...........:D

[eddieh]

Originally posted by K.R.Joye
Yes nice hull, wow a brushed combo that runs in the 50's! Now just imagine a hull almost 2 lbs lighter with the same fire power on 24 cells! Its coming...........:D

Oh Ken not to mention the 1.3 pounds less in Batteries.....
:D

[Ladamercy]

Ehhh,

sorry, but please stop dreamin`;)
Where shall the watts come from? You`ll have to draw 80 Amps to get the same output- forget it...

Regards matt

[Paul]

Hello Guys,


sorry, but please stop dreamin`

LOL, sorry, couldn't resist.:D

Paul.

[Twinpowered]

What type of course will you be running? If its an oval with wide turns: stop worrying too much about weight.
Weight has little impact when on plane. What IS a problem is that it will reduce acceleration, so it takes longer to get back on speed. So weight is only very important on courses with many (tight) turns, where speed is lost frequently.

About 30-36 vs. 20-24 cell setups: if you look at the numbers closely, you'll notice the power to weight ratio of a big motor is better than that of a smaller one. And that is including the weight of the cells. It would be different if you look at f.e. a light-weight hull with much less cells. That hull would need serious reinforcements, so more additional weight.

Next: if we look at the MHZ hull, the size and difference in weight will show you the carbon version has only 1 layer less (4 layers vs. 5). But given the way higher strength of carbon, the hull will be much stiffer and stronger.

So if you want fast and durable, get the carbon version, with 30-36 cells.

[eddieh]

Originally posted by Paul
Hello Guys,




LOL, sorry, couldn't resist.:D

Paul.

Paul, good natured ribbing is what I like best..........
seriously, how many watts does it take to push 3 lbs...
I may not need the watts.... and besides......

we got special KRJ 800grxl Whoopa$$ Watts.... these are much stronger then your average watt, they are sort of hmmmm Dreamy!!!!!!!!!:D

Hey Ken JUmp in here I am being surrounded!!!:p

[Ladamercy]

Hi,

whats so funny? We could go on discussing in german if you prefer :cool:



Regards matt (with basic knowledge of english)

[eddieh]

Matt, it is not anything you said or wrote, that is a "Slap" at the guys who think they can run 24 cells.... Paul is laughing at Me!!! :D
you have been very helpful... now another part of my education, isn't the fact that you have extra weight (gravity) pushing down, and the force of the prop, trying to keep it up expending a lot of energy?
The way I am looking at this and Please forgive my naivity I have absolutely no egineering or math skills, I look at the e-rcu guys an astro 25 12 cells 36" boat + 40 mph, so for an additional 10 " boat and 10-12 mph, I am going to need 20 cells and a 800-1000 more watts? the difference in weight should be 3-4 lbs the 36" hulls come in around 6 lbs......

[T.S.Davis]

Sweet!!!

That even sounds like an Unlimited.

[Ladamercy]

Hi,

ok, as i said before i can only speak about my personal experiences. It is of course possible to power a 1/8 scale with 24 Sub-Cs but the question is, how it will work?
How long is the runtime for your races? It is a simple formula: power (W)= Voltage(V) x Current(A). As a result you will have more ampdraw for the same power-output. If you compensate this with more capacity you`ll need larger (->heavier) cells.
The more amps the motor draws, the lower the cell`s voltage (consistant internal resistance) -> rpm decreases. In addition every component heats up and efiiciency is lowered....

Modern treated Sub-C cells like the Sanyo RC1700 can handle up to 60Acc discharges without longterm problems, but this is the absolute maximum.
Now with 1,1V/cell under load, do the math:
26,4Vx60A=1584W
39,6Vx60=2376W

This is what goes into the speedo. Now consider the efficiency of the speedo and the motor and you can subtract at least another 20-25%

For the weight i agree with twinpowered.
Example: when i run my drifter xl with 64 cells it is slower and runtime is shorter than with 96 cells (3rd pack parallel), even though the pack adds 1,8kg....

I really like to see the +40mph boat with 12 cells going more than 1,5 minutes

Another thing is that supercells like the new GP3300 might have lots of voltage and capacity but as everyone knows, NiMH cells need to be discharged at a certain temperature. So you`ll have to have good chargers and electricity at your pond to get the best out of your pack. These are things that have to be considered too!

Regards matt

[Twinpowered]

Eddieh,
It's all physics. If you want, I can mail you a excel sheet that approximates the amount of power needed to reach a given speed with given weight and length of the boat. You guys may not believe it, but it actually works pretty good even for scale stuff. I've derived it from a book about hull design.

I can also explain a bit about weight without getting too deep in math and physic formulas/models.
When planing, the boat is out of the water. Your running surface provides enough lift to support (almost) all the weight. Displacement is greatly reduced. Drag of the hull is reduced. So the main things that are important: how much power is needed to stay on plane? How much power is left to accelerate any further? How much drag is left by the parts of the boat that are still in the water?
As you can see, weight is not a real big problem in this state. It IS a problem for your RATE of acceleration. Mass introduces slowness: more weight means lower acceleration. As such, more time and thus power is wasted getting on plane.

[eddieh]

Matt, thanks for the input, but I think what is being missed is the RPM per volt, and the amount of torque necessary, I understand that you need to spin the 455/3 at minimum, of 24,000 rpm. for an example, ok the rpm is fairly easy, a motor with 1000 rpm per volt, , now we get into loaded, so it will need enough torque to spin at 1000 rpm per volt, this i understand is where the horsepower comes in, and from your example you are saying this is going to require 3.18 horsepower divided by the efficiency say 80% that is 2.5 this is still more then the 11 cc motors run in gas, and they are running over 60 mph so how do we figure the percentage of watts pushing the additional weight of the extra 8 cells, (because the most we can run here is 32.) to me it would make sense that if the hull is lighter and is moving across the surface with out a lot of lift from the prop keeping the tail up (less weight) the amount of power will be needed would be less , the use of a less lifting prop, will be more efficient for speed, as there is less energy expended in lift and more energy expended on drive, is my thinking flawed? I am not doubting what was said by twin and yourself, I am trying to see why my theory is wrong. I also think a lighter hull will have less friction, less friction , less energy needed.
thanx again for all the help, this is very interesting.
cheers eddie

[eddieh]

Originally posted by Twinpowered
Eddieh,
It's all physics. If you want, I can mail you a excel sheet that approximates the amount of power needed to reach a given speed with given weight and length of the boat. .

Leon that would be great, I really am trying to learn something here
can you send it to ejhansen@comcast.net.
sorry for being a bit naive.. it is fairly new to me. cheers eddie

[Ladamercy]

Hi Eddieh,

2.5 this is still more then the 11 cc motors

???- over here a good setup with 11ccm has more than 6 little horses.....
You can`t compare a nitroengine to an electric motor. If you check the Torque over rpm- charts you`ll see, that an electric motor has most of its torque when starting to spin.

You`re absolutely right with your thoughts but you have to see the whole combination: motor+ cells.
I do not say that a 24 cell setup won`t work (well i do however) but it is much more difficult than with 32 and you will put a lot of stress on your equipement. What is the advantage of a 24 cell setup when you have 1 min less runtime and fry your motor each run with same hull and celltype? The cells life is shortened and the heatshrink will say byebye right after the first float-out. It is just the combination and if you want to you can the extra watts as "security stock".
Power can also be defined as torque x angular velocity and especially on a hydroplane you need the torque to get the hull above waterline (enormous size in touch/friction with the water compared to other hulldesigns). This is when the motor draws most amps!
I have tried an Octura 1755 which has far smaller blades than the x Series but same diameter as the 455. Even at full throttle with a strong push the boat did not ride on the pads. Now imagine 24 cells and a smaller motor...

Regards matt

[Happy Amp´s Ch]

Hi Mathias,
first congrats to your super nice looking Hydro.This was the style i want to have as i introduced the 12 cell hydro class at the Nauticus in Germany.I have run a long time a Mr.Pringels MRP but with the years the outrigger took plaze.
How long do you life i Munich? Have you never heard from The little Oktoberfest held by the Mac Craw Casern every year.You can get you Bud can there next year.
Is eigentlich schade das wir uns noch nicht kennengelernt haben ,
ein paar tipps um das Teil noch leichter zum laufen zu bringen würden mir schon einfallen,na vielleicht geht mal was zusammen.
I am with you to get the highest volts as you can because the lost is r² x I, so if you want the same power with less volt you have always moor loss in the cable,esc,cells and motor.
As you know i do reseach with e powerd cars,trucks and busses at Magnetmotor Starnberg we rise the volts every year as the electronic parts allow it,becaus this reason.The best tuning is to lower the weight and a race boat has not to withstand a crash when it flip.Less weight gives faster accleration and less needed power on the straight.If you want to see 12 cell hydros going 40 mph + come to Ismanig and see the boats they run in 12 cell hydro class,they are all mesured 40 mph + running 5 minutes.Hans Lehner has a radar speed gun,with we do some mesure this year at the lake.Also with the motor i can help you to find a way to handle the higher volts and /or higher Amp´s with the moore efficent brushless motors.

[Ladamercy]

Hi Chris,

ich habe das Boot im Frühjahr verkauft (Mr. Breitenreicher ist der Glückliche)- somit bleibt es ja in München bzw. Ismaning. Bin im Moment wieder etwas weg vom Modellbootbauen, aber dieses Thema hier finde ich klasse!

Ok, there are boats that can go +40mph over 5min with 12 cells BUT they are hydros (purpose-constructions) not 1/8 Hydroplanes (that have to look scale).

Regards matt

[Twinpowered]

Eddieh,
For top speed, a lifting prop is nonsense. Any force not pointed forward will keep your prop from doing what is right: providing thrust.
Problem is: we also need acceleration. We have to drive the boat from the lakeside, so at a certain point we have to make a turn, or the boat will get out of range. Turning means slowing down, no matter how you look at it. Even with full power turns, drag of the rudder will kick in. To gain speed faster, a lifting prop is used to get some extra lift and acceleration.

IC engines have a bigger power to weight ratio. And for setting a record speed, a very tiny amount of fuel in the tank can be used. On the other hand, we could leave 80-90% of our cells behind to reduce weight. That should be more efficient than just using 24 cells instead of 36. :D

But back to reality. Your boat weighs ... pounds. This includes hull, receiver, motor, cells, ESC, the lot. Your power is ... watts. When you add more cells, your power is increased. But because hull, receiver, etc. still weigh the same, your power to weight is improved. Off course, the motor you use will get heavier if you make dramatic changes. But that heavier motor has a better efficiency. Look at the datasheets of 700 to 800 size motors: efficiency goes slightly up when size increases: from 71% to 82. All in all: bigger is better, mainly because it is more efficient. There are limits of course, but for us those are mostly $$ based.

[Happy Amp´s Ch]

Hi Matt,ist aber schade den Du bist ein First Class Builder wie ich es von den Photos her beurteile,so sauber mit den schönen Deteils bauen nicht viele.
Maybe a Depron(thin foam plate) /Carbon composite is the right stuff to build a super light hull,a friend has build a B2 Aircraft with this material with 4 m wingspan weight very less.
Does any know the plannumber of the "Smocing Joe"Camel sponser Hydro from R.Newton.

[Kmot]

This is really an awesome thread! I am learning quite a bit reading this. :)

[Kmot]

Here ya go Christian:

http://www.newtonmarine.com/158_plans.html

[Ladamercy]

Hi,

@chirs: Danke für die Blumen! Ich habe schon ein feines Projekt für die kalten Wintertage und es wird natürlich wieder superscale ;)

@twin: sorry, but a hydroplane is something completely different compared to a mono or cat. First it is a 3-point construction, which means that the only parts of the hull touching the water at speed are the back ends of the sponsons and the half submerged prop. Therefore the cg is located far to the front end (best at the lateral balance point of the skidfin) and the back of the hull has to be very lightweight. Due to the nontrips the back has to come out of the water because otherwise they will act like rails and the hull won`t turn worth a darn. To lift the hull above waterline you need to angle the strut or use a prop to create lift..once the back is above the water, you have won and the boat will fly :D

The RCU guys should have a lot of experience with those potentialities...

Regards matt

[eddieh]

Originally posted by Ladamercy


I have tried an Octura 1755 which has far smaller blades than the x Series but same diameter as the 455. Even at full throttle with a strong push the boat did not ride on the pads. Now imagine 24 cells and a smaller motor...
Matt I would think the 1755 would have more pitch then the 455 I believe the 1755 would be 1.7 x Diameter and the 455 1.4 x diameter , but I could be wrong... the 4 series is a much lower lifting prop if I am not mistaken. so the problem seems that you need more thrust and less lift, anyway this is a great discussion and I think I am learning lots.... cheers eddie

[Ladamercy]

Hi Eddieh,

sorry it is exactly the opposite. The X Series have huge lift due to their "ears"...

Regards matt

[Twinpowered]

Sorry, but I don't totally agree. Lifting prop is something to avoid. With the real deal, the speeds get high enough for the body to provide lots of lift. The centre of gravity is rougly the middle, because for a wing, that's where the lift is generated. For scale, the numbers don't add up. Other means of providing lift must be used. So a lifting prop is selected, which in turn further decreases speed.

This limited speed is also why your wings didn't work like the real hydro. If we want aerodynamics to really kick in, at least twice the current speed must be reached. As this is only hobby, we don't get to spend hunderds of thousands of dollars on a hull. So, our speed and progress is a bit slower. But look at it this way: at least your 1/8 was a heck of a lot faster and cheaper than 1/8 of a real one.

Lets all be glad not everything on this planet is scale. ;)

[eddieh]

Matt here are the numbers from the octura prop chart
prop dia pitch

1755 2.17" 3.689"
x455 2.17" 3.038"


so don't know what that is telling us but the pitch is steeper on the 17 series, meaning it would be harder to spin, requiring more power, that is why it prefers the 455 as more thrust, but from your other comments she is riding a bit wet in the back,
here is a good site for the prop charts
http://www.larrysplace.com/nitro/files/prop.html
thanx for your interest in our problems this is great!!!




:p

[Ladamercy]

Hi,

yes, as the number implies the 1755 has 1.7xdia of pitch. This is a bit more than the X4.
I don`t think that the plett wasn`t able to spin the 1755 to full rpm but it was the prop itself that made the problem. The blade surface of the 1755 is to small and deliveres not enough thrust when completely submerged (the blades are very thick compared to those of the X Series).


@twin: I´m only talking about the backend of the hull not the entire airtrap.
I would say that a liftproviding-prop is absolutely essential, especially for racing. It creates the lift much more constant and faster than an airfoil, which can be helpful in tight turns.


And aerodynamics can be an important factor even at our speeds: http://www.mattas.de/Videos/1to8blowover.mpeg


:D

Regards matt

[Kmot]

Wow! I find it amazing that the hull was nearly upside down yet came upright again before landing in the water! 8)

[Twinpowered]

Matt,
Each force has a point at which it grabs onto a body. If you change the centre of gravity to the front, more pressure will be on the sponsons and less on the back. By lightening the back, your essentially reducing weigth AND changing your centre of gravity. Both are good in this situation: less lift will be needed.

In an ideal situation, the centre of gravity, the lift of the body, and also all hydrodynamic forces will grab onto your hull on one single point. Why? If speed increases, no trim is needed. If airspeed suddenly increases (wind), you will not flip or dive. You will get airborne and loose speed, but you won't crash (well, not like this at least).

Your example shows what happens when the forces are not balanced. But it also shows us weight isn't a problem if enough airspeed is obtained: the airflow generates enough lift. So the design of the hull does exactly what it's supposed to do. Now if we only had the means to reach that speed, yet with enough weight not to get airborne...

And I think I already mentioned a lifting prop will provide lots of help in turns. With the big boats, trimming is essential to get up to speed quick enough. We could try to build something similar. A mechanism for changing the angle of the shaft on the run should be possible to build into a hull this size. That way, the amount of lift for the prop could be greatly reduced, maybe even removed when progress of technique allows.

[Andrewg]

a 1/8 isnt magic its a bigger scale hydro - the X series props are most popular in electric and nitro classes

we have a big advantage over nitro by virtue of the boat being light

in our use weight matters!

F=MA or A=F/M (corrected) ie power to weight ratio affects acceleration

when does acceleration happen? In everyturn. Using a stopwatch you will find you spend half your time on an oval course turning

So for at least 50% of your runtime you are accelerating - its called radial acceleration when you are turning.

Then there is the first 1/2 of the straight - where the acceleration is linear.

So your boat is accelerating for nearly 3/4's of the time it is on the water.

The cell with the highest energy content for the weight is the 1950AUP which weighs 38 vs 64 for 3300. Like a supercharged CP1700.

[Ladamercy]

Hi,

@twin: i really do understand your point of view. The interaction of hydrodynamics and aerodynamics makes the correct setup of a hydroplane so incredibly difficult.

The problem is that you have two different cgs on a hydroplane:
1. The static cg
2. The dynamic cg

When you have the boat on your bench it is quite easy to set the static cg. Balance it the way that only little weigth is left on the strut.
This static cg is influenced by the location of your components like motor and batteries.

The other cg can only be determined when the boat is at speed and enough airflow is created to produce ascending force. This is influenced by many factors: size of the tunnel, nontripheight, rearwing assembly, canardangle, all radii on the deck- hull transition, thickness of the airfoil,...
All the hydrodynamic factors would add to this: the size and shape of the riding pads, their angle of attack and of course the prop including its characteristics and the strutdepth + angle.

I think you will agree, that it would take huge effort to find out specifications on that. You would need a wind tunnel and very potent computers for simulations to find it out.

It is a real challange but that is what makes it so interesting!

@andrew:F=MA or A=M/F ie power to weight ratio affects acceleration

what do you mean by that? F=MA or A=M/F :confused:

Regards matt

[B.K. Foster]

A meeting of the minds of FE potential Nobel Prize winners in the field of aero/hydrodynamics... Good thread guys... Love the vids too... :D

Laters,
Bry

[Andrewg]

force = mass x aceleration (its a newtonian equation of motion)

therefore

acceleration = force/mass

ie less weight = more acceleration

[Turbosun]

ehhh Andrew, the notion that a higher-mass boat goes around a corner slower because high mass limits the "radial acceleration" given an equal propulsion force is a fundamental misconception.

Just because direction is constantly changing and a force is necessary to effect this change in direction, does mot mean that a lower-mass boat with the same propulsion system will do this faster.....In fact rounding a buoy at constant speed may result in a centripetal acceleration but angular acceleration is ZERO. Only when you want to increase speed (and hence angular acceleration), mass will be limiting....The angular equivalent for F=m*a for rotating objects: M=I*alpha, where M=moment, I is Ineertia (integral r**2dm) and alpha is angular acceleration.

It is the rudder and hull creating the force allowing the boat to turn, NOT the propulsion of the prop.....

Because the lift generated by the rudder is limited, the mass of a boat will have a major effect on the minimum allowable turning radius at any speed. Thus for equal boats with different masses, in principle, the lighter one would be able to turn tighter turns at any speed...

[K.R.Joye]

You guys keep bench racing and theorizing i'll be working on my boats! Everything will be frozen around here in a month or so. Good stuff! :p

[AndyKunz]

Originally posted by Ladamercy
@twin: i really do understand your point of view. The interaction of hydrodynamics and aerodynamics makes the correct setup of a hydroplane so incredibly difficult.

Au Contraire! It's what makes it incredibly simple. You should be dealing with the center of pressure vs CG to provide stability, exactly as is done in an aircraft.

You should pass the driveline through the CG from all axes, and if you can't, make it pass ABOVE the CG. This provides stability increase at higher speed (see Bonneville sites for more information) but increases the "weight" that the sponsons must lift. Check out design rules for ducted fan aircraft, especially electric ones, because they exhibit many of the same properties.

Basically, consider a planing hydro an aircraft and things suddenly become much easier.

Andy

[Ladamercy]

Ehhh,

and how can i find out the exact location of the center of pressure???

Regards matt

[AndyKunz]

Aircraft design software. Note that it changes position according to angle of attack (alpha), but with proper shape design (ie, rear lifting, no lifting prop needed) you can put the lift behind the CP and CG quite easily.

This is why I prefer Sport hulls over Scale. Full-size boats aren't often built by somebody with an understanding of what they're doing wrt airflow. With a Sport hull you can get around that.

Andy

[T.S.Davis]

hahaha Come on Andy. Aircraft design software? All of us FE boat hacks have aircraft design software. Because it makes setting up a hydro so easy. Incredibley simple to be exact. So we all have it. Accept me I guess. I'll just borrow Kens or something.

Challenging, even fun, but easy? Maybe for you.

[AndyKunz]

Terry,

We're talking about Big Buck Boats here. If you're going to do it right, you need the right tools. If you are happy running somebody else's design that's not a problem, either. Go with what works for you.

On the UL-1 I used tools I've been using for years on airplanes. Did we get it perfect? No, we had to add 1/8" to the bottom of the ride pads.

Do they blow off the water easily? I'll let the owners answer that.

On the Patriot hydro (essentially a scaled-up UL-1 with cleaner cowl aerodynamics) we had to change the right sponson ride pad. Runs great with that change. It doesn't blow off either - it would, though, with the earlier pad, because it was glued down too hard.

BTW, the Patriot ran as fast as a similarly-powered UL1 even though it was 30" instead of 24.5" long.

I'll post a link to some videos of it soon.

Andy

[Twinpowered]

Andy,
You're right. A hydro at full speed is much more like an airplane than like a boat. At speeds around the 70-100mph mark (varies a lot with design) 70-90% of lift for hydros or cats is generated by air.
Look closely at video's of full scale hydro's: airborne behaviour is more practice than exception. If you can turn the switch, and think of cats, hydroplanes and hydrofoils as planes, things simplify enormously. Work with wingloads, cords, wingarea, etc.

Matt,
Scale doesn't work. You simply can't scale everything up and down, and expect everything to work te same way. Why? Because the forces aren't lineair. Most of the time they are squares or something like that.

[Ladamercy]

Hi,

Scale doesn't work

i never doubted that!?

All i can say that i have built one of those 1/8 scale hydroplanes and it took me about one year from the day i got the hull until the boat was going flatout through a turn without the back end dropping and loosing speed.
I don`t have any aircraft design software but it took much much more time to trimm it correctly compared other hulldesigns (a drifter for example, where you just throw everything in and pull the trigger for 65mph).

Regards matt

[AndyKunz]

Originally posted by Twinpowered
You're right. A hydro at full speed is much more like an airplane than like a boat. At speeds around the 70-100mph mark (varies a lot with design) 70-90% of lift for hydros or cats is generated by air.

It's a lot lower than 70 MPH.

Look closely at video's of full scale hydro's: airborne behaviour is more practice than exception.

Not from what I've seen, especially in the non-Unlimited classes.

The vast majority of them pay little heed to what would make a better airplane. They go for very fast, but not good fast. Bud has done a lot in that regard for the teams, but I still think JR started down that path a long time ago. Whiner Dave has his good points too, not just in propeller implementation.

Andy

[Happy Amp´s Ch]

Hi All,
about propellers,the x4 serie props have rake so this props have less lift the 17 serie the competition serie have no rake this are high lifting props.The 17 serie prop need a cuping to make moor trust to make them a good starting prop.Also it´s a good way not to cup the prop(cuping rise the pitch),only a small grove(called Johnson 5 therm section) grind on the presure side befor the trailing edge gives good starting trust(the prop grip is harder).
The V9 serie props are high rake props with low lift and high pitch.
With higher pitch the lift rise,also deeper blade rise the lift
Note also the Unlimeted Hydros are designed with staight prop shaft that have an angel of attack no flex propshaft.I run them only with straight shaft and had no problems.
To find a good trim i lett some boats fly,i realy push them trou my garden and set the cg that the boat does a fin flight.An other way i have done when i was young was to mount some weels on the side and pull the boat with a string of a sailplane starting device over a big parking lot.With less weight the cg is the same as with full racing weight,only the speed of take of is much less and easy to find with a esc for the pullmotor.

Thank you Kmot,i will order the plan.

[Andrewg]

TURBO

I didnt say it goes around a corner slower because higher-mass "radial acceleration"

I said the boat is accelerating thru a turn - and it is - it is slowing - and the motor fights that ie the motor is loaded under acceleration/deceleration and coming out it accelerates ie its loaded and accelerating. Mass contributes to both those accelerations directly, and indirectly thru its impact on factors such as drag. (T- We have done this before help people out or bicker with me - its your call)


Matt

boats can be scaled - for 1/8 simple non froude calculations are very accurate for these boats. To save you the trouble there is a scaling table at www.fastelectrics.com

http://www.fastelectrics.com/Scalefactorssimplemk2.xls

it is fun to play with and for 1/8th the neat thing is most of the variables are familiar and about right for electric power. It also has the equations in the cells so you can see how each variable is treated

just use google to get the parameters of the boat you want to model

I have a more sophisticated version if u want it emailed

[Twinpowered]

Sorry Andy, but unlimited is all we get to see over here. And even that not too much (propably don't want to spoil us). I've only once seen non-unlimited run on TV. From what I recall they were indeed running pretty wet, if that is what you mean.
Could also be they only show the nice races over here every now and then. Or the ones with spectacular crashes. Who knows, my perception of this world could be totally wrong. ;)

About the transition zone: you're right if you mean it starts much lower. 50mph could be a start. But it varies a lot depending on design: from 50-75mph is not uncommon. The end is even wider: 70-100 (and 100+). And I'm pretty sure you can find lots of hulls that operate outside that box. The end of the zone is what I'm trying to designate as a target to reach.

Matt,
A year isn't that bad. I even consider it pretty quick, given the problems you must have had. But what you, Andy and others said about setting hulls up is more or less what you should expect:
When inexperienced, put a motor in a mono and it will more or less perform. But be prepared: it's going to be difficult to get the last drop of performance out of it.
With the same amount of (or lack of) experience, put a motor in a hydro and you're in a lot of trouble. But later on, things get a lot better a lot faster.

But what about my idea of trim? I think everyone agrees dynamic trim is needed. If not yet now, then in the future?

[AndyKunz]

Originally posted by Twinpowered
Sorry Andy, but unlimited is all we get to see over here. And even that not too much (propably don't want to spoil us).

Limited races are a lot more fun to watch, even though they are a bit slower. The Grand Prix boats (popular in Northeast US and Canada) are some of my favorites, and the Unlimited Lights. They also have quite a few more sponsors and designs, giving more variety ("flavor") to choose from.

Andy

[K.R.Joye]

ANDYs correct the limiteds are great to watch and talk about hulls tech and Aero those guys are very creative in there designs.

ANDREW G. hows your light layup coming i'm interested in what your final product weighs in at. Also are your hulls gel-coated?
I don't recall you telling us what motor & setup your using. Your thoughts on power and weight being a big factor in the turns are right on! Nice chart BTW.

Also nobodys mentioned how the lighter (24 cell)setups will have a advantage getting on plane and `staying on plane' when thorottling down in traffic and setting up for the start countdown. The heavier boats sink down real fast and may be tougher to get on plane as valuable seconds tick by in race situations.

[AndyKunz]

Originally posted by K.R.Joye
Also nobodys mentioned how the lighter (24 cell)setups will have a advantage getting on plane and `staying on plane' when thorottling down in traffic and setting up for the start countdown.

Ken, I don't think anybody in MI knows anything but "full throttle" :D

You aren't allowed to come off plane for the start - you have to stay up.

There is certainly an advantage to a lighter boat in that regard - Andrew touched on it. The question is, does a 25% increase in power for a 30 cell boat (over a 24) compensate enough for the 20% increase in powertrain weight, and the 10-15% increase in overall weight?

That should be pretty obvious.

Andy

[Paul]

Hello Guys,
The question is, does a 25% increase in power for a 30 cell boat (over a 24) compensate enough for the 20% increase in powertrain weight, and the 10-15% increase in overall weight?
Yes. There's way more to it than what's being talked about here. I plan on powering my boat in one of two ways, either 64 1950s or 32 full Cs. Either way it's more weight than 3300s and I'm not so concerned about it. With the power of a 2250 combined with a gearbox it should be easy to motivate the boat. I don't think I'll have a problem getting the boat to plane quickly, especially with the large amount of props available.

I still say paper and practice are two different things. The power and props are way out of scale so how can it be compared to the real thing? I think the video of Matt's boat should put things in perspective.

Paul.

[Steve Vasdekis]

I understand the method behind the 1950 parallel theory, but the cell can only handle 30 amps so doubled it can split 60 amps, your voltage will still be lower than just using the C cells which can handle 50 amps without losing much voltage at all. Also another thing to consider is that since you are pushing the 1950 to the limit one in 64 is bound to give.

[Ladamercy]

Hi all,

a 2250 combined with a gearbox

why are gearboxes so common on the other side of the pond?
Over here nobody uses them especially on large motors.
Isn`t this enormous waste of precious energy particularly with toothed wheels???

Regards matt

[K.R.Joye]

I have a feeling the 3000 Full c's are going to be the cell of choice with the 1/8s. I bet Mr Hill will be one of the biggest benifactors of this proposed class.LOL

Andy(quote)
Ken, I don't think anybody in MI knows anything but "full throttle"(quote)

ANDY thats how i usually end up winning races! LOL
Just have to watch i don't hit their overturned rockets as i'm finishing the race.
Ken:p

[Steven Vaccaro]

What are the thoughts about how many laps the race be? Are you guys going all out for 2 minutes or a longer slower 4 minutes?

[AndyKunz]

I'd say go for 1 mile = 6 laps on a nitro course.

Will MI Cup have a big enough pond?

Andy

[eddieh]

Originally posted by Pagemaster
What are the thoughts about how many laps the race be? Are you guys going all out for 2 minutes or a longer slower 4 minutes?

well the other guys will probably be done in 2 minutes, but with only 24 cells it is gonna take me 4.... :D

[Paul]

Hello Matt,

why are gearboxes so common on the other side of the pond?

The gearbox isn't really common over here. There are a "few" of us who really belive and understand how to use them. The losses on the gearbox are minimum compared to overall preformance gains. With the gearbox you can fine tune a setup where as you are limited to what you can do with direct drive, paticularly in regards to prop selection.

My motor selection will be the 2250 10 turn.

Paul.

[AndyKunz]

Originally posted by Ladamercy
why are gearboxes so common on the other side of the pond?
Over here nobody uses them especially on large motors.
Isn`t this enormous waste of precious energy particularly with toothed wheels???

Matt,

It's because some people believe what gear vendors tell them. Or they don't like it when facts contradict their preferences.

OTOH, Jay Turner and Pat McDonald have shown that in the 4-cell classes it's a stalemate as to which is better.

Andy

[Paul]

Hello Matt,

Isn`t this enormous waste of precious energy particularly with toothed wheels???

I have a 1/12 scale H&M Bud Viper that I run a Lehner 5000XL on 12 cells with a gearbox. The prop is a x440 3 blade, if you blow on the prop it will spin so I think it's safe to say there is no lost energy.

Paul.

[Paul]

Hey Andy,

It's because some people believe what gear vendors tell them. Or they don't like it when facts contradict their preferences.

LOL, ask DT Jr about my "preference".

Paul.

[K.R.Joye]

STEVEN
I thought 6 laps nitro or 10 laps on an FE course was the original idea. However long it takes you to get there, its up the way you setup your boat.

Hey i'm doing this for fun, just to see if its feasable. Did you order a hull yet Steven or are you still kickin tires?

[Twinpowered]

Matt,
Your right, there's always some loss in power with any gearbox. But sometimes the loss is regained: a gearbox does allow you to run a wider range of props with the same motor. For some situations, the ideal prop simply doesn't (yet) exist, so that's where gears can be used to correct the rpm/torque of the motor to the best alternative.
And you're not correct about the gears on this side of the pond. They are used for big stuff, but it ain't for motors. It's with high torque IC engines, where gears are used to raise the rpm by 1.5-2 times. If direct drive was used on those engines, the prop would have to be huge, heavy, and expensive.

[Ladamercy]

Alright,


from my knowlegde the torqueband of a modern electric motor doesn`t require any over- or underdrive. And for adjusting to different props, hmm...

Can you show me a pic of a lightweight gearbox (w cog wheels , no belt) that can handle a 2250/10s rpm and torque on 30 cells without blowing up in thousand pieces?

@twin: i think, we`re talking about electric motors only...

Regards matt

[Steven Vaccaro]

Did you order a hull yet Steven or are you still kickin tires? Yes I'm still tire kickin. Especially since it could take a year to get setup right!!! I don't jump into anything. I'm still waiting to see all the rules laid out and in to law.

[Paul]

Hello Matt,

Can you show me a pic of a gearbox (w cog wheels , no belt) that can handle a 2250/10s rpm and torque on 30 cells without blowing up in thousand pieces?

Here ya go. That's a 355/40 Plett on there.

http://www.skullcaps.com/boats/ss457.jpg
http://www.skullcaps.com/boats/ss458.jpg

http://www.finedesignrc.com/hardware/turbotrans.gif

Paul.

[Ladamercy]

Hi,

really impressive but i still don`t understand the necessity of it?

Are those wheels made of delrin? How many shaftrotations do they stand and what is the winding of that plett?

It seems to be a 1/8 hydroplane. 24 cells and overdrive on a 355/40 plett- meine Herren! :nono: :D


It looks like a 1,5 ratio- poor Motorbrushes :hammer:

Regards matt

[AndyKunz]

Matt,

I think you will find the specs for the gears on the Stock Drive Products website.

Andy

[Paul]

Hello Matt,

Are those wheels made of delrin?
Yes.
How many shaftrotations do they stand and what is the winding of that plett?
Well, I have run them on the XL5000 and 12 cells which equals 75,000 RPM at the motor geared to roughly 35,000 RPM at the prop. The Plett is a 6 turn.
It seems to be a 1/8 hydroplane.
It's a S-Sport boat, 36 inches long 19 inch beam. It's a bit smaller than a 1/8th scale.
meine Herren!
LOL.
It looks like a 1,5 ratio- poor Motorbrushes
You gotta break some to make some.:D Your right on the gear ratio, 1.5 overdriven.

Paul.

[Ladamercy]

Hi Paul,

thanks for the answer!

So if it is a 6 turn, why not save some weight and losses and put a 4 turn directdrive in?
The ampdraw when accelerating must be critical with this setup, no?
Have you ever tried a directdrive in this boat for comparison? That would be very interesting!

What about resonace and critical frequency on those gears? Is there no problem with those high rpms?

Regards matt

[eddieh]

Matt,
Paul is being Modest, this is a gorgeous boat although we consider it slightly puny in our standards, we do admire and applaud Paul for exploring the world of Micro hydros.
here is a thread to look at some more pictures and details
http://www.rumrunnerracing.com/feforums/showthread.php?s=&threadid=9172
this is roughly about the size of the boat that e-rcu run at 1/10th scale

Paul, seriously, I never get tired of looking at that beauty!!!! outstanding (but small)

:D

[Paul]

Hello Matt,
So if it is a 6 turn, why not save some weight and losses and put a 4 turn directdrive in?
I would like to try a 4 turn arm but you can't get them around here. I need to find an easy source. The weight is only a few ounces for the GB.
The ampdraw when accelerating must be critical with this setup, no?
Yep, she got pretty warm with this setup. I was running a x460 3 blade. I never tried direct with it so I can't give a comparison.
Is there no problem with those high rpms?
No gear failures to date, I lube them with a spray silicoln which seems to work very well. So far I haven't replaced any of the gears I use for wear either.

Paul.

[Happy Amp´s Ch]

Hi Matt,
i am with the US guys to use a gear,i have a 2240/10 with a 1,6 : 1 tothbelt HTD gear that can handle the power of 30/cells without any problem.Belt is 15mm wide and has a 3mm tothpitch.With this combo i do some mesurment between my outrunnermotores and the geard set up.
The reason is that if you can turn a 65 mm prop on you 1/8 Hydro and with that propsize you jump out of the water and the propefficency is also better at this size,speed and power.We talk not about SAW boats where the spezivication is much different.To get the speed of 55-60 mph it is better if you turn a bit lower but a bigger prop.Try a prop with moore pitch ration than 1,4 and take a motor with lower winds that can handle to amps better and has most a better efficency at higher amps.I had run a modified Astro 40/4 wind in my Mr Pringel 1/12 hydro turning a x445 prop.In Germany we start from stand still at the drivers plaze and i was always the first at the first turn.Best accleration was the goal to win many races.

[Twinpowered]

@twin: i think, we`re talking about electric motors only...

Oeps, wrong forum... ;)

But lets do a small recap of what I think everybody agrees upon so far:
1. Acceleration is important: need to reach topspeed as soon as possible after a turn. For acceleration low weight is a plus, and high power too. So power to weight ratio is important.
2. Lift is important: more lift after a turn will mean a dry hull and better acceleration. As lift increases with airspeed, speed and direction (wind influence) will cause constant variations, so a way to remove or compensate lift is needed, or wet running or blow over will occur.
3. Stability is important: you need to finish a race to win. So balancing the hull both for static and dynamic forces is needed. And also another form of stability is important: the hull should be strong enough to last a long time.
4. Prop choice is important: you want to remove as much lift as possible. Plus: you want good acceleration with a high topspeed. So prop choice will very a lot depending on hull, course and conditions.

Where does this all lead to:
- We need higher voltage motors. I think everybody agrees our amps are reaching its limits. So a logical way to go would be a higher voltage, as per P=V*I ampage goes down when voltage increases. And an added advantage will be the total setup will be more efficient (lower losses in wires, ESC, motor).
- We need lighter cells. Coincidently, with the lower amps, smaller cells could be used. Unfortunately, more are needed (bummer). But the lower amps should make it possible to use different cells in the future like Li-ion, Li-poly or (in the far future) fuel cells. Those cells have a higher energy density, which will lead to lower weight.
As the C rate is lowered, it could even mean we can use more or less "mainstraim" cells, which will lead to cost reductions. And those will propably be needed very much, as both motors and ESC will very likely be more expensive.

P.S. Andy, I think you did see this one coming when designing the emperor?

[Steven Vaccaro]

Anyone remember these hulls by Performance International?

http://www.offshoreelectrics.com/images/shared/BlackHwkHydro.JPG

I emailed him to see if he's still making them.

[AndyKunz]

Originally posted by Twinpowered
P.S. Andy, I think you did see this one coming when designing the emperor?

I've been considering it for a while. A year ago I told people here in phone conversatiosn that I expected the BL hype to cause a backlash to brushed motors for high cell counts. Eventually the BL will catch up, but for now the reliability of brushed motors and ESCs far outweighs the need to perform routine maintenance.

It is my estimation that you are witnessing that backlash.

In about 18 months it will be back to brushless.

This year my 10-24 cell control has BOOMED! It used to be my lowest seller (aside from the discontinued 4 cell) but this year it was right up near the top while the BEC controls (usually best seller) went to the bottom.

It's a cycle.

Andy

[Jeff Shriver]

"Anyone remember these hulls by Performance International?"

Boy that boat looks very close to a H&M Viper Turbine (#11029) that has been enlarged. Nice looking boat. How big?

[Dennis Whitt]

I just dont get that one Andy...Talk about Hype !

[Paul]

Hello Andy,

It is my estimation that you are witnessing that backlash.

What your witnessing Andy is sticker shock not reliability issues. I've pushed the smaller BL stuff to it's limits and still haven't had a failure. The bigger brushless stuff is even more forgiving. For example my S-Sport boat was giving me fits with the Plett and one of your controllers, switching to a big Aveox and a Hacker 77 fixed my problems using the same props.

I think it's great people are trying the brushed motors but for the performance I'm looking for BL gets my money. Lets face it, the proof is in the pudding, we'll all know next year.:D

Like I was told Andy, don't knock it till ya try it. I'm a beliver now.

Paul.

[AndyKunz]

Paul,

I have about 12 brushless motors and controllers.

Andy

[Paul]

Hello Andy,

I have about 12 brushless motors and controllers.

In boats?

Paul.

[Twinpowered]

Andy,
I'm quite sure in the end BL will THE motor of choice (give em some time to grow, they'll learn it).
At the moment it's not, at least not over here. I've seen some figures of BL vs. Brushed setups at this forum, but over here, those numbers don't add up. Here, BL isn't used very much, it's almost all 700 size, or a Ultra/Plett every now and then. Cost is still way to high to even consider BL. I could buy a 355/50/5, ESC and then some more for about the same money as what I would consider a "medium" BL setup (24-cell motor and ESC).

So Andy, when the time comes BL is all that is sold on the other side of the pond, this could be the country to dump your surplus items. :D

[AndyKunz]

Or it could be the place to launch a new Brushless line.

Andy

[Twinpowered]

Or it could be the place to launch a new Brushless line.
Ahh... I think I can read a new business plan: let's take over part of the BL market. No more sleep, so double in size next year. Shall we start a poll for # 1024 for next year? ;)

[eddieh]

well as an outsiders observation, I really believe the top speeds will be with brushless hands down. but I think the "fun" factor, and what Paul P says really rings true, how many guys will you get to build this thing? well at the cost of it over a 1500 not many it is true, but if you like to build, you like scale and would be as happy running say 40-45 as 50-55 for quite a bit less then I think there will be a huge explosion.... once the proof is in the pudding, and I do believe there will be room for everyone, and it could be divided up much like the current Namba hydro racers, the one thing that isn't in doubt, if your going to build something it is so much cooler to make it BIG!!!!!!

I also understand the guys who may be a bit jaded on speed and I say man go for it, you got the frog skins spend them, but I also like the idea of getting all the guys on the sidelines who believe me are gonna watch and wait until there is some data, and they are going to want to see both data sets brushed and brushless...and then they will decide which speed fits there pocketbooks and thrill needs, for me I look at e-rcu and think man these guys are having a blast, I truly respect there building skills, and as the only member (currently) of the Jersey chapter of e-rcu I am envious the races are so far to drive too. but if they were 8-12 hours away I would try to make everyone. When I look at all the great pictures that Sheltered and Jim clark put up ... it's the fun factor that makes it all worth while.... and they are using outdated equipment, running it the best it can be run... maybe it's why you see so few mig-29's running against f-15's at the reno air races? could they go faster...I suppose so, but what brings all the folks in is seeing old warbirds mixing it up... this of course is just my opinion, I am so psyched about building this project, I am sitting with a grin on my face for the last week or two,, and that is priceless to me....
cheers eddie

[AndyKunz]

Eddie,

Great comments. On a technical point, the only jets they race at Reno are L-39's. The AT-6 class is the biggest in terms of participation (cheap to operate, fun to fly, lots of airframes available). It's also right up there in terms of audience appeal. Kinda like LSH.

The Unlimited class is where the P-51's, Bearcats, and P-38's race. It is the high dollar class, and very few can afford it, but the speeds they turn brings out a lot of fans. It has no shortage of audience appeal either.

I think there's room for both kinds of performance in model boats, and there will probably be both sets of guys in another year or two. And it's good for all.

Andy

[Paul]

Hey guys,

you like scale and would be as happy running say 40-45

I'm not busting on you Eddie but what combo are you going to run to hit those speeds? As I figure it with the combo I have laid out for my boat I'll have roughly 33000rpm at the prop with big torque to boot.

All I can go by is my experiance with the S Sport hull, on 24 cells I was hitting the speeds your talking about with BL power. Granted there was allot left in it but in a bigger boat I "think" it's going to be a tough nut to crack getting those speeds out of a tool motor. A plett on the other hand.... Who knows, you may end up with a screamer that will walk all over my setup. Wait a minute, did I just say that? Naw, just kidding.:D

TTYL, Paul.

[eddieh]

paul, if everybody said yeah that'll work great the only happy people would be the hobby dealers, so if you see something stinky I would just as soon here it before I go peeling frog skins... so you don't think the big ol can a whoopa$$ can do it??? LOL, I am thinking that I have to decide how fast I want to go. 35-40 I still think the 800 grx can do it, but am waiting for some numbers from ken....

and i love the discussions I was actually listening, what I thought I would try.. was this combo
24 cells still thinking on chemestry and size I like what steve vasdekis said about them but obviously I am not an expert, 355/40/3 or 4 turn, direct drive, rc hydros penguin speed control, if not I have an astro 207 d that might be ok in the meantime, I am thinking to try a 4 blade cleaver from propshop 52mm lots of pitch if not that I saw a prop recommended in the plett site which was a carbon fiber 63mm, absolute scale rudder, made from thin aluminum sheet filled with chopped kevlar , micro balloons, and epoxy
I hear rich ballantine might be working on a killer skid fin, that has a water pickup built in... sounds pretty trick, but maybe it is only an idea... I am thinking stainless wire drive ball bearings in the business ends a scale looking adjustable strut.
I am also considering having the spoiler adjustable, inside the tunnel connected to one of andy's ride attitude controls but haven't thought about it that much yet

and if this all don't work, the allison will be so lifelike I'll just fire that bad boy up!!!:D


so that's all the cards on the table.... whatcha think...
I for one love constructive critcism..


oh by the way if anyone does know an armature rewinder I would love to have the armature of this absolutely huge mega motor I have rewound... 3 turn

[eddieh]

Paul one more thing I am going to try/test is a carbon fiber foam sandwich for structural members, I have also heard an excellent discussion regarding a honeycomb method of structure building which sounds really cool, I also seen this composite sandwhich which begins with diagonally crisscrossed carbon fibers, sourounded by foam, the laminate two very thin carbonfiber layers to the outside and then disolve the foam, there is a thin epoxy that will surronf d the fibers basically making a very ridgid and superstrong material, but of course cost considerations....

[Andrewg]

Paul and Eddie

I think Paul is correct about power tool motors

Their have been two big leaps in motor efficiency in the last 10 years Neo magnets and brushless

Neo magnets enabled the motors to remain efficient at high current levels ie they flatten the power curve between peak power and peak efficency

Brushless motors using neo magnets accentuate that effect particularly at high current at high rpm as the electro mechanical limitations of brushes at high rpm are avoided.

A major reason for brushless extending top speed over brushed designs is that they make much better power at peak efficiency which tends to be closer to peak rpm

Power tool motors arent oriented toward maximising output at maximum rpm. But rather high torque at modest current consumption. They tend to be higher resistance than most of the high performance motors being considered.

Paul

how are you calculating your prop rpm?

Ken
the light layup is on the end of the queue of glass orders, a new mold and baot (28" atlas van lines), a nitro rigger, some new molds and an industrial project. But I expect I will have it up and runnign during your winter - maybe.

There are a couple of these shovels running now in 1/8th so we know the stock weight and have an idea how much we can leave out with eash layer of laminate and things like stringers etc. It was put to me this way - "I can make it as light as you like - but much reinforcing do u want to use?" I feel that in the end it will be the ability to contain cells and motors in a boat hitting a bouy at 55mph or cartwheeling which will determine how they are built.

The motors I have are a hacker b50 Xl/gearbox and a collaborator has a big Robbe (brushed) for 36 cells. If things go well I will add an Aveox 4643/1.5 to that lot ie similar to unsensored 1817/1.5. Problem is the Aveox will be a first in that wind so there are some fees to pay for winding jigs.

[eddieh]

Well some interesting enlightenment for me. I was looking on the other forum at the Calculations post by Brooks
and it finally dawned on me what Paul was trying to say (and Andrew etc) regarding RPM , well according to the calculator I should be somewhere near my goal, my question is yes it gives me the rpm and then the prop size to use as a ballpark starting area, (very very cool by the way and simple if you think about,,,)
I know that motor x will give me 1000 rpm per volt, I know that I will be using 24 cells x 1.1 volts =26.4 so that will give me 26,400 rpm, but for argument sake lets just say 21,000 rpm, now according to the calculator if i can spin a 455 prop, at 21,000 rpm I should be up around 48 mph, but how do I fugure out how many watts are "Required" to spin that prop I mean 20,000 rpm seems to be a safe number but how do I select a motor that can turn a 455 at 20,000??? is there a variable I am missing?
thanx for the help

[AndyKunz]

Eddie,

It looks like it clicked for you.

Get The Motor Handbook by Bob Boucher from Astro Flight. Order direct from Astro. In it you can find a table showing prop size and watts required for certain RPMs. It will get you on the trail to finish your quest.

You are very close, Grasshopper.

Andy

[eddieh]

Andy, Finally ordered the book.... (just now) and i will wait with more motor questions till I have had a read, anyone feel like talking spoilers now?? LOL, I was thinking about using one of your (subtech) controllers for an adjustable spoiler in the shovels tunnel, maybe something like when I start to get too much lift the spoiler would lower a little and reduce lift... is this thing being over engineered that the returns wouldn't be worth the effort?
I was thinking it could be as simple as vanes set as at a certain angle for my "standard spoiling effect but then the angle would increase when I want to disrupt more air
for instance || is normal and /\ when I am getting too much lift
am I whacked??? (I mean more then usual):D

[AndyKunz]

We won't know until you try. The APC 4 is really tiny and can be stuck to the side of the servo it controls if you want. I would just recommend that it operate w/o servo input (I can ignore it in the software).

Andy

[Jeff Shriver]

by Ladamercy -
"I made adjustable flaps (via servo) but deactivated them later. They didn`t affect the boat`s attitude..."

I believe Matt (Ladamercy) tried a variable spoiler on his 1/8 Miss Bud but later removed that operation. You may have to investigate to see if it worth the time and effort to add them.

[AndyKunz]

That was a different type of boat. YMMV to an extreme.

I had an adjustable canard on my original Patriot hydro. It made a big difference with or without it, and the angle too - aerodynamics DOES matter at 30+ MPH.

But the pitch sensor I used didn't have the throughput needed to keep the boat level, and vibration caused a lot of excess noise causing the wing to flutter.

If I had gone with a smaller movable surface and changed other things, it would probably have been OK. I just didn't have time to experiment.

Andy

[eddieh]

jeff I was thinking that, but I am building a shovel, the "tunnel" is more defined. I am running lighter (24 vs 36 cells) also going back to the different style of boat, he was trying to get ride adjustment from the two spoilers sort of like aelirons. I am not looking to adjust the ride more like bleed off lift more of a problem with shovelnoses then modern hydros, it is just thinking out loud and i appreciate the input... and if anybody has Ideas like i said I am more then happy to listen....:)

[Kmot]

didn't have the throughput

Andy, what does the expression throughput mean in laymans terms?

[AndyKunz]

Ability to receive an input, process it, and send it back out again.

The APC-3 used an analog sensor, the APC-4 uses a digital one.

Andy

[Kmot]

Ah so, thanks! :)

[DJ Campbell]

Originally posted by Eddieh
jeff I was thinking that, but I am building a shovel, the "tunnel" is more defined. I am running lighter (24 vs 36 cells) also going back to the different style of boat, he was trying to get ride adjustment from the two spoilers sort of like aelirons. I am not looking to adjust the ride more like bleed off lift more of a problem with shovelnoses then modern hydros, it is just thinking out loud and i appreciate the input... and if anybody has Ideas like i said I am more then happy to listen....:)

Hi Eddie,

On my LSH shovel, I removed the air traps in back of the sponsons. (Pretty common on the other shovels I've seen) - this may or may not apply to 1/8, you may need the air.

Also, there are those "V" shaped spoilers under the tunnel in some shovels. I've seen them on plans and there is one on my 1/10 scale fiberglas shovel I bought from the 1/10 scale guys in Seattle. To be honest, I don't know if they help to reduce airflow or not. Maybe someone can chime in on that one.

[Paul]

Hey Eddie,

355/40/3 on 24 should work okay. Stay away from 3/4 blade props on a boat this size. Belive me you'll be happier with a 2 blade. High pitch is not a good idea on the plett, go for diamiter. I tried a V955 and it spun it but it was much slower than a x460, you need the rpm with the higher pitch. As for making the wing adjustable, on my boat I'm not going to mess with it, I plan on a netural setting. I'm not so sure with the amount of area as opposed to the weight of the boat that it will make a differance.

I just finished detailing all the wood of my Atlas, I'll post a pic of the "mess" later today but I'm pretty sure that it would fly well on 24 cells. It's much easier to grasp what's going on when everything is out in front of you. Sure is allot of wood.:D

Paul.

[eddieh]

Hey Thanx Paul... was looking for some specs on the 3 turn? hollein had it listed... but no specs , and plett don't list it... regarding the "spoiler" it is not for a "wing" it is for that bump or spoiler in the tunnel (shovelnose), that Doug was talking about,,, funny I gave away a v955 to arvad to test he didn't like it with his set up, diameter huh? ok will think about that one too... batts full c or 3300's or are you set on the 2600's or the 1950 aup's.... just want to see where everyones thinging is at, I have 24 brand new 2400's... and about 75 2000's.... but used....I am a little leary about the nimh becuse if we vent a cell and a little spark,,, well who knows....

[eddieh]

Originally posted by DJ Campbell
Hi Eddie,

Also, there are those "V" shaped spoilers under the tunnel in some shovels. I've seen them on plans and there is one on my 1/10 scale fiberglas shovel I bought from the 1/10 scale guys in Seattle. To be honest, I don't know if they help to reduce airflow or not. Maybe someone can chime in on that one.

Doug was thinking about this post too, I think Andy or one of the other flyguys should chime but I think the object of the spoiler was more to disrupt the airflow lessening lift, this is what i was thinking anyway, so that means that my diagram may be backward, we would want that spoiler to close causing maximum disruption, or open so there is little when I need the lift... man lot I have to learn in a hurry....

[Twinpowered]

"V" shaped spoilers under the tunnel in some shovels
I assume you mean out of the water? That should be for guiding air and/or increasing rigidity. A thin flat plate needs support or it will bend under pressure. Adding a profile will give it strength. A "spoiler" (pretty sure it has a different name) over the length of the tunnel will guide air, and reduce turbulance somewhat. But as such it shouldn't be needed: turbulance should be eliminated otherwise. Last time I saw huge ones it was on the wing of a plane (F-86 Sabre).

[AndyKunz]

No, Twin, it's a V that works much like an air dam on a VW GTI.

Andy

[eddieh]

"In hull form, Slo-Mo-Shun IV closely resembles the familiar three-step hydroplane. It is different, however, in one important respect-it has a small V-bottom section at the bow. At speed, a conventional three-step hydro rides on just the two side sponsons and the extreme stern. If the speed goes high enough, air flowing into the tunnel formed by the sponsons creates enough lift to make the boat become semi-airborne. This results in a dangerous loss of directional stability. To overcome this, Slo-Mo-Shun IV has the afore-mentioned V-bottom section at the bow. It's called a "spoiler" and serves to break up or "spoil" the unwanted stream of air."
here is a picture with some rough ideas...

[Twinpowered]

No, Twin, it's a V that works much like an air dam on a VW GTI.
Sorry, wrong direction of mounting from my side. Couldn't understand why he called it a spoiler. Cleared now.

[Ladamercy]

Hi,

"Flaps
by Ladamercy -
"I made adjustable flaps (via servo) but deactivated them later. They didn`t affect the boat`s attitude..."

I believe Matt (Ladamercy) tried a variable spoiler on his 1/8 Miss Bud but later removed that operation. You may have to investigate to see if it worth the time and effort to add them."

Thats right, the Bud had adjustable Flaps at the front end.
I think the size of my flaps was just too small but it would surely be different with one single canardwing like the ones on modern ULs.
The rear wing was adjustable too (Bowdenwire) and i tried different angles. It was ment to alter the lift and actually worked pretty good.

Best regards matt

[Twinpowered]

Great example Eddieh.

If I was to design a hydro I would propably design it with a smaller cord to reduce lift. That would also reduce the fronts cross section, thus lowering resistance of the air. On the other hand, it wouldn't be such a nice shovelnose.

To control lift, a construction like Matt suggest would be ideal: increase lift at low speeds, reduce it at high.

BTW very nice construction Matt.

[eddieh]

Leon, (twin) that is what I am doing I think, Andy Kunz designed a circut that keeps submarines level, it acts upon the control surfaces so the bow of the sub is neither too high or too low.. level, I was going to use this circuit to adjust the "flow" of air through the tunnel, when I need the lift it will be wide open no (spoiler) but as the nose gets higher it will begin to close the two spoilers in essence working as a throttle on the air, I will need to find the optimal postion of the spoilers first, and I will also need to see if this would be legal under "scale" rules... but it is really a cool idea, I will not manually adjust it as i believe andy says it can adjust a thousand times a second or a minute not sure... but will be able to run flat out down the straights with a little edge in the fact that the air under the hull is being regulated...so a blow over is less likely... that is what gave the Slo Mo Shun it's edge in it's day...

[DJ Campbell]

Originally posted by Eddieh
...but I think the object of the spoiler was more to disrupt the airflow lessening lift, this is what i was thinking anyway, so that means that my diagram may be backward, we would want that spoiler to close causing maximum disruption, or open so there is little when I need the lift...


A V spoiler design for a shovel may be worth some experimentation during your testing period. Who knows, on a large boat like that it may be effective. I would think that there are some nitro guys who know a thing or two also about shovel blowovers, etc. You could make different sizes out of foam or balsa and try 'em out. It's a piece that looks like it would be relatively easy to add on or remove. LOL! :D:D

[Twinpowered]

Great solution Eddieh, I was about to explain that controlling it during "flight" would make ones life pretty miserable. If you look at cockpit shoots of real ones, those guys are making constant adjustments to trim. But they are strapped down in their seat, and can use both hand and feet to control things.

I take it the gyro also has a input for speed? At lower speed the controls should travel more: the airspeed is lower, so the effect is less.

[DJ Campbell]

Originally posted by Eddieh
I will not manually adjust it as i believe andy says it can adjust a thousand times a second or a minute not sure... but will be able to run flat out down the straights with a little edge in the fact that the air under the hull is being regulated...so a blow over is less likely... that is what gave the Slo Mo Shun it's edge in it's day...

Eddie, I posted before seeing your latest post. Interesting idea! I may want to experiment with that too on a smaller hydro.

[Turbosun]

Here is a pic with the cabin on it...
The rear (separate) hatch is partially covered by the cabin/air intake hatch.

[AndyKunz]

Originally posted by DJ Campbell
Who knows, on a large boat like that it may be effective.

It's effective on O & P Sport boats. Ask Dick.

Andy

[Turbosun]

Here is on of the two wings which have a wider wing root for efficiency and easier mounting...

[Turbosun]

Note the 2 cm offset of the cabin to allow for easier counterclockwise turning...This lic is taken looking at the bottom...

[Andrewg]

Eddie

RE: I know that motor x will give me 1000 rpm per volt, I know that I will be using 24 cells x 1.1 volts =26.4

that voltage figure is relevant if you limit current draw to 30 amps. Output will be

24*1.1*30*85%=637 watts

you hsould be able to run 55 amps continous but you will be heading for .95v/cell

24*.95*55*85%=1065 watts

And by then you will be turning about 19400 rpm which equates to about 42 mph if the 455 is the prop.

Rther than how do I make the motor turn a X455, I would think more along the lines of which prop is right for the motor. If you have anything around a 450 start with that and work up - you are in greenfields so the correct prop may be a surprise.

X400, and X600 with the same pitch but smaller diameter, seem to work well on Pletts